Allison IC-20'S (in original boxes for 20 years!)

[newandold]

Hi All,

Just wanted to get started here at The Classic Speaker Pages.

My story is almost 3 yrs old now and has posted on another forum, but I believe this is a better place to continue and enhance the discussion of Allison Speakers in general, so anyway here I am.

During the coming weeks I would like to revisit that story (from my topic thread) here and just generally, continue the discussion of "anything Allison" here in a more secure web space, along with these other fine classics!

Regards,

Bill Mina

[tysontom]

Bill, I'm with you on this site. It is stable, reliable and organized. Hope others from Yahoo join in as well.

BTW, your Allison IC20s look beautiful and "like-new." It's good to see a pristine pair that is completely original. Could you post some other pictures of the speakers?

—Tom Tyson

[newandold]

Hi Tom,

Here's a few.

The picture with the "saran wrap" around the speakers was taken in Mass. before I showed up to retrieve them. Amazing, they were packed that way for the last storage, which was 17 years.

Before that, they were in use for about 5 years all together. First used around 2 years, then repacked in the original cartons for 3 years, and again, brought out for another 3 and finally packed away in 1995.

As can be seen from the back photo, they are as pristine there, as in the front.

The first shot is, as they now sit, with the image control modules powered and running.

Bill

[JKent]

Hi Bill

Welcome to CSP!

Roy Allison made some great speakers. My first speaker upgrade was from AR-4x's (still have them) to Allison: Fours. I loved the Fours but eventually sold them because we moved to a house with a vaulted ceiling and their upward-firing woofers were not ideal for that setting but I have good memories of them.

Of course the Fours were pretty entry-level compared to the megabuck IC20s but all Allisons were nice. I now have some other "Roy Allison" speakers--AR-3a's.

Wonder how the IC20 compares to the AR-9.......

-Kent

[tysontom]

Hi Tom,

Here's a few.

The picture with the "saran wrap" around the speakers was taken in Mass. before I showed up to retrieve them. Amazing, they were packed that way for the last storage, which was 17 years.

Before that, they were in use for about 5 years all together. First used around 2 years, then repacked in the original cartons for 3 years, and again, brought out for another 3 and finally packed away in 1995.

As can be seen from the back photo, they are as pristine there, as in the front.

The first shot is, as they now sit, with the image control modules powered and running.

Bill

Bill,

Those are truly pristine, easily the best-looking pair of IC20s I've seen. Howard's IC20s are also nice and in mint condition, but he's heavily modified his pair with crossover changes, removal of the push-pull woofer configuration and removal of the remote-control setup, including the indicator lights. Somehow, they are not IC20s any longer.

—Tom

[newandold]

Hi Bill

Welcome to CSP!

Roy Allison made some great speakers. My first speaker upgrade was from AR-4x's (still have them) to Allison: Fours. I loved the Fours but eventually sold them because we moved to a house with a vaulted ceiling and their upward-firing woofers were not ideal for that setting but I have good memories of them.

Of course the Fours were pretty entry-level compared to the megabuck IC20s but all Allisons were nice. I now have some other "Roy Allison" speakers--AR-3a's.

Wonder how the IC20 compares to the AR-9.......

-Kent

Hi J,

Thanks for the welcome!

Yes, I can understand doing away with the fours with a vaulted ceiling.

For around 5 years, I owned a pair of AR 2ax driven by the AR amplifier. Nice clean sounding combination. Completing that system was an XA turntable using a Stanton 681EEE with that rather rare shibata stylus.

I would have loved a pair of 3a's but at that time were decidedly out of my reach.

That's an interesting thought, comparing the AR-9 to the IC20.

I would think the similarity would end with the dual woofer setup.

The IC's use the push pull configuration of the woofers to reduce even order distortion.

The approach with the 9 was to control the low frequency response of those dual 12" bass drivers with a rather sophisticated electronic crossover network. The forward firing upper array delivers a more pin point imaging over the IC.

That of course, is where personal preference comes in.

Both systems, ironically, are rated for a max. amplifier power of 400 wpc.

Bill

[newandold]

Bill,

Those are truly pristine, easily the best-looking pair of IC20s I've seen. Howard's IC20s are also nice and in mint condition, but he's heavily modified his pair with crossover changes, removal of the push-pull woofer configuration and removal of the remote-control setup, including the indicator lights. Somehow, they are not IC20s any longer.

—Tom

Yes, Howard has been on quite the journey with that pair of his.

I do take my hat off to him for his amazing woodworking ability and his rather interesting approach to the image control problem.

He has also changed with his listening taste in recent years, now being a fan of mainly the "focus mode" inner panels mainly. Although with his latest incarnation, the inner panels run full tilt with nothing at all going to the outer panels.

In "stock" form, there is always some output to the opposing panels, though greatly reduced. Always, the output of the system (stock) is the same though shifted.

For myself, the whole thing is moot, because I never cared about the image control aspect of the loudspeaker. Only that they would play in "Omni" mode.

With the power to the modules switched off, the speakers always remain rock solid with full continuity to all drivers.

Bill

[StereoDude]

Bill,

Those are truly pristine, easily the best-looking pair of IC20s I've seen. Howard's IC20s are also nice and in mint condition, but he's heavily modified his pair with crossover changes, removal of the push-pull woofer configuration and removal of the remote-control setup, including the indicator lights. Somehow, they are not IC20s any longer.

Tom

Tom,

Are you trying to rattle Howard's chain again?

Yeah, they are modified, but "heavily"? That, to me, seems to say they sound like a different speaker. I don't think the change from push pull makes a noticeable difference. He's got a upper end frequency rolloff which is the same that many would do with an EQ or with the slope switch in a different Allison model.?The biggest change seems to be the change in focus mode. It seems like he's going for more of the A3 sound without the corner placement. I'm sure they still sound like Allisons, and I bet they still sound essentially like IC-20s.

-Phil

[tysontom]

Tom,

Are you trying to rattle Howard's chain again?

Yeah, they are modified, but "heavily"? That, to me, seems to say they sound like a different speaker. I don't think the change from push pull makes a noticeable difference. He's got a upper end frequency rolloff which is the same that many would do with an EQ or with the slope switch in a different Allison model.?The biggest change seems to be the change in focus mode. It seems like he's going for more of the A3 sound without the corner placement. I'm sure they still sound like Allisons, and I bet they still sound essentially like IC-20s.

-Phil

Yes, Howard has been on quite the journey with that pair of his.

I do take my hat off to him for his amazing woodworking ability and his rather interesting approach to the image control problem.

He has also changed with his listening taste in recent years, now being a fan of mainly the "focus mode" inner panels mainly. Although with his latest incarnation, the inner panels run full tilt with nothing at all going to the outer panels.

In "stock" form, there is always some output to the opposing panels, though greatly reduced. Always, the output of the system (stock) is the same though shifted.

For myself, the whole thing is moot, because I never cared about the image control aspect of the loudspeaker. Only that they would play in "Omni" mode.

With the power to the modules switched off, the speakers always remain rock solid with full continuity to all drivers.

Bill

Bill and Phil,

Well, I do tend to tweak on Howard; I've known him for many years, and he knows that I kid around with him quite a bit.

As for his IC20s, they are certainly in mint condition with nary a scratch or mark of any kind on their cabinets. In Howard's case, they are an integral part of a surround system, and he is constantly experimenting with the spectral balance, and I think he has moved to more of that "focused" mode to give him less of a diffuse image, I suppose. If he were using them only for 2-channel stereo reproduction, then I doubt he would have tampered with them so much, but now he's completely into the modifications to suit his surroundings. He doesn't rely on the excellent woofers for bass reproduction (he uses two big subwoofers), and now he doesn't like the very wide dispersion of the panel arrangement, I suppose.

When I listened to the IC20s for the first time at the Chicago CES in 1987, I heard them operated in their different operating modes just briefly, but the Omni mode was clearly the best for me.

—Tom

[Carlspeak]

Howard F. used to post here regularly some time ago but left after a row with a now deceased troll. Perhaps someone who knows him well could coax him back?

He has a wealth of knowledge about Allison for sure.

[newandold]

Howard F. used to post here regularly some time ago but left after a row with a now deceased troll. Perhaps someone who knows him well could coax him back?

He has a wealth of knowledge about Allison for sure.

Hi Carl,

It's nice to be on board here, thank you!

Howard is aware that I have suggested getting all the Allison discussion back here where It works best, I believe.

He's a little worried, with all the classics here for discussion that he may no longer get any sleep!

That being said, I don't think he will pass on it, especially when it starts (and it will) to heat up a bit.

If I got the story right, the "troll" was talked about quite a bit last week on the "other" forum.

Interesting, the upgrade to this website, pretty much coincided with the move of the Allison Forum from Topica.com over to Allison Loudspeakers on Yahoo groups (2006/07).

Too bad everything didn't come here right there and then.

Best Regards,

Bill Mina

[newandold]

Bill and Phil,

Well, I do tend to tweak on Howard; I've known him for many years, and he knows that I kid around with him quite a bit.

As for his IC20s, they are certainly in mint condition with nary a scratch or mark of any kind on their cabinets. In Howard's case, they are an integral part of a surround system, and he is constantly experimenting with the spectral balance, and I think he has moved to more of that "focused" mode to give him less of a diffuse image, I suppose. If he were using them only for 2-channel stereo reproduction, then I doubt he would have tampered with them so much, but now he's completely into the modifications to suit his surroundings. He doesn't rely on the excellent woofers for bass reproduction (he uses two big subwoofers), and now he doesn't like the very wide dispersion of the panel arrangement, I suppose.

When I listened to the IC20s for the first time at the Chicago CES in 1987, I heard them operated in their different operating modes just briefly, but the Omni mode was clearly the best for me.

—Tom

Hey Tom,

I want to take a step back with regards to Howard's IC's and point out what got him started (at least my understanding) doing any modifications to his speakers at all.

Who knows how many years ago, the image control modules on his units began to act up and shift all over the map from one mode to the other.

With no "fix" coming from Allison Acoustics on this, Howard pulled all that from the system and just hard wired the things into Omni, wanting to get everything out of all drivers, all the time. Quite a contrast to where his head is now, but back then, quite different.

I would bet the farm if the IC modules proved to perform flawlessly as advertised, he would never have done anything to those systems, except to maintain and enjoy.

Bill

[tysontom]

Hey Tom,

I want to take a step back with regards to Howard's IC's and point out what got him started (at least my understanding) doing any modifications to his speakers at all.

Who knows how many years ago, the image control modules on his units began to act up and shift all over the map from one mode to the other.

With no "fix" coming from Allison Acoustics on this, Howard pulled all that from the system and just hard wired the things into Omni, wanting to get everything out of all drivers, all the time. Quite a contrast to where his head is now, but back then, quite different.

I would bet the farm if the IC modules proved to perform flawlessly as advertised, he would never have done anything to those systems, except to maintain and enjoy.

Bill

Bill, I think you are quite right about Howard's system. The electronics went south, and he couldn't get a reliable fix. BTW, how do your electronics work at this point? Have you had to intervene, or have they "stayed the course" and given you reliable service?

Once he had changed his system, he went on to other things, such as changing the woofer configuration from push-pull to conventional, and then he did other things. Overall, his 20s still look like 20s, except for the lights on the front, but changes lurk underneath. I actually think he has toyed with the idea of changing the drivers to some degree, mainly because of his fear that the Ferrofluid has dried, causing attenuation in output in the treble. He did go in and change the crossover somewhat to compensate for the lost output.

—Tom

[newandold]

"BTW, how do your electronics work at this point? Have you had to intervene, or have they "stayed the course" and given you reliable service?"

" I actually think he has toyed with the idea of changing the drivers to some degree, mainly because of his fear that the Ferrofluid has dried, causing attenuation in output in the treble. He did go in and change the crossover somewhat to compensate for the lost output."

—Tom

Hi Tom,

About 2 years ago, I figured out, quite by accident that there was no problem after all with the "electronics", referring of course to the image control modules contained within the IC-20.

The problem is with the transformer that is supplied with the IC-20, and/or a combination of the electrical value of that transformer, plus the fact that it is an ungrounded (no 3 prong).

Some combination of those factors CAN lead to some "interesting" behavior of the panels switching unexpectedly.

The discovery came about when I happened to be sitting there with the power to the modules switched on (I have the transformer plugged into an outlet switch so I can keep it off except for listening sessions when I choose to alter the imaging.)

I turned the lights on in the room and noticed that one of the speakers switched to the outside panel with the action of the wall switch!

After noticing that, I played around for a while with the remote control AND the wall switch. I could consistently switch the panels from one mode to the other while keeping the button of the remote depressed, while turning the lights on and off in the room, (even doing it by turning the lamp on and off from the switch on the lamp itself.)

So, what does it all mean??

Nothin' to me, actually.

That of course is because my preferred mode is always "Omni" and the instability is a non issue when the power to the modules is switched off.

The system is designed to default with no relay power to the Omni position.

Referring to the other comment about "age related" attenuation, In my view that is absolutely incorrect.

This whole issue of condition of the fluids and being able to measure the impact with any consistency just isn't possible.

There is no ferrofluid in the IC tweeters for starters, they are cooled with silicone grease, and HF himself once said the grease doesn't dry out but the ferrofluid is more likely to do so........what?

Your tweeters in the second generation A1 have the same grease.

Do you suspect there is a measurable drop off in your tweeters and would this apply to every greased tweeter?

Also, what about the "mileage" playing into it? not just the age?

I have an NOS A1 tweeter in stock from 1988 with zero hours on it. It would be interesting to measure that tweeter against one that has been up and running for decades and compare notes.....indeed.

Bill Mina

[tysontom]

Hi Tom,

About 2 years ago, I figured out, quite by accident that there was no problem after all with the "electronics", referring of course to the image control modules contained within the IC-20.

The problem is with the transformer that is supplied with the IC-20, and/or a combination of the electrical value of that transformer, plus the fact that it is an ungrounded (no 3 prong).

Some combination of those factors CAN lead to some "interesting" behavior of the panels switching unexpectedly.

The discovery came about when I happened to be sitting there with the power to the modules switched on (I have the transformer plugged into an outlet switch so I can keep it off except for listening sessions when I choose to alter the imaging.)

I turned the lights on in the room and noticed that one of the speakers switched to the outside panel with the action of the wall switch!

After noticing that, I played around for a while with the remote control AND the wall switch. I could consistently switch the panels from one mode to the other while keeping the button of the remote depressed, while turning the lights on and off in the room, (even doing it by turning the lamp on and off from the switch on the lamp itself.)

So, what does it all mean??

Nothin' to me, actually.

That of course is because my preferred mode is always "Omni" and the instability is a non issue when the power to the modules is switched off.

The system is designed to default with no relay power to the Omni position.

Referring to the other comment about "age related" attenuation, In my view that is absolutely incorrect.

This whole issue of condition of the fluids and being able to measure the impact with any consistency just isn't possible.

There is no ferrofluid in the IC tweeters for starters, they are cooled with silicone grease, and HF himself once said the grease doesn't dry out but the ferrofluid is more likely to do so........what?

Your tweeters in the second generation A1 have the same grease.

Do you suspect there is a measurable drop off in your tweeters and would this apply to every greased tweeter?

Also, what about the "mileage" playing into it? not just the age?

I have an NOS A1 tweeter in stock from 1988 with zero hours on it. It would be interesting to measure that tweeter against one that has been up and running for decades and compare notes.....indeed.

Bill Mina

Bill, you figured out what you needed to do to maintain the "Omni" settings without having to go in and try to rebuild the entire circuitry, and that makes sense. Just set it to the Omni position and unplug the power module; problem solved.

I had forgotten that the IC20 did not use Ferrofluid in the tweeters, but rather used silicon grease. Roy Allison used this with the AR-6 tweeter as well some other AR versions, but the examples I have here show no sign of deterioration of the grease. Roy did tell me that excessive power could easily "boil" the grease, allowing it to work its way out of the gap or worse, harden, but I think this would be quite uncommon. The grease probably does change slightly in viscosity over time, however, and this might cause output problems with the tweeters at high frequencies.

I would love to see a comparison of the tweeter output with your NOS 1988 tweeter and one that has been in use for many years. The big question might be if there is any truly significant change in output over time. Maybe you could get DRM or someone to compare that tweeter (if you wanted to chance such a test, which always makes me nervous) with an existing one that he might have. I've got a LinearX LX500 system on order—it's only been on order for the last 4 years—and if it ever gets here I'll let you use it to compare the two with some definitive measurements.

—Tom

[newandold]

Bill, you figured out what you needed to do to maintain the "Omni" settings without having to go in and try to rebuild the entire circuitry, and that makes sense. Just set it to the Omni position and unplug the power module; problem solved.

I had forgotten that the IC20 did not use Ferrofluid in the tweeters, but rather used silicon grease. Roy Allison used this with the AR-6 tweeter as well some other AR versions, but the examples I have here show no sign of deterioration of the grease. Roy did tell me that excessive power could easily "boil" the grease, allowing it to work its way out of the gap or worse, harden, but I think this would be quite uncommon. The grease probably does change slightly in viscosity over time, however, and this might cause output problems with the tweeters at high frequencies.

I would love to see a comparison of the tweeter output with your NOS 1988 tweeter and one that has been in use for many years. The big question might be if there is any truly significant change in output over time. Maybe you could get DRM or someone to compare that tweeter (if you wanted to chance such a test, which always makes me nervous) with an existing one that he might have. I've got a LinearX LX500 system on order—it's only been on order for the last 4 years—and if it ever gets here I'll let you use it to compare the two with some definitive measurements.

—Tom

"Bill, you figured out what you needed to do to maintain the "Omni" settings without having to go in and try to rebuild the entire circuitry, and that makes sense. Just set it to the Omni position and unplug the power module; problem solved."

Yes Tom, when there is no power there cannot be any shifting, which of course as an "Omni" fan, well, that's perfect.

As you well know, I am a HUGE fan of maintaining this particular pair of IC's as close to the factory as possible.To that end, perhaps when I retire, I may act on my own plan to address the weakness of the modules so that they can be used dependably without altering the speaker in any real invasive way.

The first two places to start will be trying a higher quality, grounded power supply of the same electrical value as that Chinese transformer that was shipped with the loudspeakers.

The other is to add a dedicated circuit to the listening room (isolated ground and home run neutral to the panel).

The latter is what I believe is the REAL answer. These things are overly sensitive to interference from other electrical load that share the same neutral.

So anyway, no rush and I may never even bother, since I prefer image control via center channel.

"I would love to see a comparison of the tweeter output with your NOS 1988 tweeter and one that has been in use for many years. The big question might be if there is any truly significant change in output over time. Maybe you could get DRM or someone to compare that tweeter (if you wanted to chance such a test, which always makes me nervous) with an existing one that he might have. I've got a LinearX LX500 system on order—it's only been on order for the last 4 years—and if it ever gets here I'll let you use it to compare the two with some definitive measurements."

It could be interesting, but that tweet is one of my prize puppies, and NOBODY (in reality) is getting it!

I'm going to get into parametric eq. in a later post, that in my opinion, is the practical solution for addressing changes to these loudspeakers, no matter what they are (unless blown).

Altering crossovers can be done as some have, but is not a solution for most.

I have not even used this feature yet, but it's on board my new Emotiva XMC-1 processor. With it, I can do full graphic equalization of up to 7 channels independently, and store those results in one of 3 speaker presets. Additionally, I could save as many combinations as I want onto the flash drive.

Bill

[Howard Ferstler]

Hey, I am back.

Here is some poop on those IC-20s of mine. The IC circuit switching acted up almost from the beginning and I finally decided to hard-wire the things into the omni mode and leave it at that. I gutted the IC network, and removed the sensors and lights on the front, covering the holes with a small brass plaque that says "Allison." This was my first mod and I could pull it off, because I had the crossover and IC schematics, courtesy of Roy.

The second mod, done some years later, was a complete rebuild of the crossover network, following the factory specs. This involved replacing the old, back-located crossover mount with standard 5-way binding posts and rebuilding the network (new caps, new resistors, same chokes) on a triangular-shaped board that was screwed to the interior bottom of the cabinet. While the original cap arrangement had some poly jobs for the mid and tweeter sections and one standard non-polarized job for the woofers, the replacement caps I used were all poly types, including a physically huge one for the woofers. Because the new network used up some space at the cabinet bottom, the original reversed woofer tube would no longer fit, and so I re-configured the woofers both facing forward, just like with the Model One. Because I use outboard subwoofers for the frequencies below 80 Hz the modest increase in even-order distortion caused by this change would be meaningless. More on the subwoofers, below.

However, now I have even more substantially modified my IC-20s, basically installing TWO crossover networks into each. The original network had to kind of split the difference in terms of choke and capacitor values, because it had to sometimes handle both four tweeters and four mids (omni mode) and at other times handle just two of each, with only a modest amount of feedback from the greatly attenuated other-panel drivers (focus mode). This works OK, because of the wide coverage capable from the mid and tweeter drivers, but it actually was not as perfected an arrangement as Roy got with either the Model One and Model Two units, or the Model 9 and CD-9. Those have the crossover chokes and caps precisely aligned with the fixed driver loads.

Yep, two separate networks in each system.

The one for the inner panels is similar to the version in the Model One: two tweeters, two mids, two woofers; and with some subtle changes (slightly different series choke and capacitor values) to compensate for driver aging with the midranges, plus going to second-order filtering for the tweeters to protect them better than what was possible with the first-order filtering of the Model One. (Note that the factory IC-20 also used second-order filtering for its four tweeters, as do all of the CD and AL series systems.)

The outer panels each have their own crossovers (mounted on still another board and screwed to the interior rear of the cabinet, just above the binding posts), with the parameters similar to the mid/tweeter sections of the inner panels. The mid-tweeter panel networks are wired in parallel (each is nominally 8 ohms, like a Model One, with parallel wiring delivering nominally 4 ohms), and the outer panels can be turned off with 20-amp-rated switches. No changes were made to the networks for the woofers, which run together full time.

Both panels have their driver complements fully protected by a total of FIVE polyfuses, each sized for the loads involved. The original IC-20 had three.

Further mods involved some additional switch work. The inner panels have permanent resistors installed in their networks and those resistors partially mimic the "concert-hall slope" Roy made possible with the Model One's own switching option. The slope chosen for the inner panels was somewhat between Roy's full slope and the less aggressive middle slope. The outer panels use slightly larger contouring resistors, given them the full-slope contour. This means that the outer panels play one or two dB less loud than the inner panels when they are turned on.

An additional switch for each outer-panel section allows the option to drop the output of the turned-on outer panels about 6 dB lower than the inner panels, kind of splitting the difference between the focus and omni modes. Finally, two additional switches allow the user to decrease the output of any of the panels in operation several dB in two stages. Because of impedance differences seen by those switches when either the inner or outer panels are in operation they offer up different attenuation amounts. With just the inner panels working each switch uniformly drops the mid/tweeter output by roughly 2 dB. With both panels in operation each switch uniformly drops the id/tweeter output by roughly 4 dB. These attenuations do not change the slopes of the contouring; they just change the mid/tweeter section outputs in relation to the woofer outputs below 350 Hz. The switches used for this additional contouring and shaping are also 20-amp rated jobs, and I do not expect them to develop oxidation problems.

Most members of the Allison group I belong to know that I also employ flanking "ambiance" speakers, with a pair of side-wall mounted Model Fours each 30 inches away from the front wall and sitting on 5-foot high bookcases (these Fours are also modified to pretty much mimic what Roy did with the Model Four he designed for the Kentucky people) and a pair of Model Eights (modified to mimic the network behavior of the later CD-8) at the same height and on identical bookcases flanking the listening couch further back into the room. The output levels of these four surround speakers are MUCH lower in level than what we get with the standard Dolby set-up parameters, because it is their job to add a comfortable amount of simulated hall ambiance to the classical and baroque music I listen to the most. In my case they were initially set and then modified by the program in my mid-grade Pioneer receiver. I use the Dolby "height" mode to deal with those more forward surround speakers. I can leave the receiver settings fixed, because this installation is used for music listening only.

This package also has a single, floor-standing center speaker (38 inches tall, with an angled-back slightly front panel) that uses Allison mids and tweeters in an MTTM vertical array, with a single Model Four woofer. The crossover network for the mids and tweeters is identical to that for the inner-angled panels of the IC-20s, with the woofer network mimicking what we have with the CD-9. I built the cabinet myself out of thick, solid cedar and MDF. The grill is a cut-down IC-20 grill. It has no level controls, and it is set to operate about 2 dB below the standard Dolby set-up level.

The installation also has two subwoofers: cylinder types, 68 inches tall, 14 inches in diameter, with Dayton Reference drivers, and with power coming from a Crown XLS1000, 350 wpc power amp. An ART equalizer contours the sub outputs below 80 Hz.

This arrangement with the IC-20s allows me to both shape the radiation pattern of each system from wide (but favoring the inner angles) to the usual, dual-panel super-wide pattern, and to adjust brightness levels when faced with recordings that are a bit too brittle sounding for my taste. Most of the time I run just the inner panels, plus the center and surrounds, with the slope adjustments turned off.

This is a lengthy description of what I have done, following parameters set up by Roy long ago and not wildly experimental, but with some changes that are related to driver aging.

If anyone is interested I can post some photos, at least once I figure out how to do it.

Howard Ferstler

[tysontom]

"Bill, you figured out what you needed to do to maintain the "Omni" settings without having to go in and try to rebuild the entire circuitry, and that makes sense. Just set it to the Omni position and unplug the power module; problem solved."

Yes Tom, when there is no power there cannot be any shifting, which of course as an "Omni" fan, well, that's perfect.

As you well know, I am a HUGE fan of maintaining this particular pair of IC's as close to the factory as possible.To that end, perhaps when I retire, I may act on my own plan to address the weakness of the modules so that they can be used dependably without altering the speaker in any real invasive way.

The first two places to start will be trying a higher quality, grounded power supply of the same electrical value as that Chinese transformer that was shipped with the loudspeakers.

The other is to add a dedicated circuit to the listening room (isolated ground and home run neutral to the panel).

The latter is what I believe is the REAL answer. These things are overly sensitive to interference from other electrical load that share the same neutral.

So anyway, no rush and I may never even bother, since I prefer image control via center channel.

"I would love to see a comparison of the tweeter output with your NOS 1988 tweeter and one that has been in use for many years. The big question might be if there is any truly significant change in output over time. Maybe you could get DRM or someone to compare that tweeter (if you wanted to chance such a test, which always makes me nervous) with an existing one that he might have. I've got a LinearX LX500 system on order—it's only been on order for the last 4 years—and if it ever gets here I'll let you use it to compare the two with some definitive measurements."

It could be interesting, but that tweet is one of my prize puppies, and NOBODY (in reality) is getting it!

I'm going to get into parametric eq. in a later post, that in my opinion, is the practical solution for addressing changes to these loudspeakers, no matter what they are (unless blown).

Altering crossovers can be done as some have, but is not a solution for most.

I have not even used this feature yet, but it's on board my new Emotiva XMC-1 processor. With it, I can do full graphic equalization of up to 7 channels independently, and store those results in one of 3 speaker presets. Additionally, I could save as many combinations as I want onto the flash drive.

Bill

Bill,

I would blame you one iota for not wanting to part with that tweeter even for a test. For one thing, sine-wave testing, or white-noise testing for that matter, is stressful on any driver -- even with short-term tone-bursts -- and like you, I wouldn't want to do anything like that. Your remedy to use equalization to bring up the treble is probably -- by far -- the best way to handle any attenuation in the treble, even if that is necessary. Save that tweeter.

Another thing: the treble dispersion on the IC20 is so outstanding that the integrated acoustic-power output is better than almost any other speaker, and therefore the high-frequency output into the reverberant field would more than offset the slight attenuation that might be occurring at the frequency extremes! Yeah, perhaps that last half-octave in the 15-20 kHz region is down a bit on axis, but the power response is probably ruler-flat out to at least 15 kHz, so what's not to like about that! There are any number of exotic speakers with great "imaging" and ruler-flat on-axis frequency response in the direct field that would fall flat (no pun intended) trying to put energy into the reverberant field. Poor off-axis performance assures that a directional speaker that sounds "spacious" and "3-dimensional" in the direct field, toed-in pointing to the listener a few feet away, will almost always sound dull and lifeless once that listener moves back into the room's reverberant field. It is amazing how much poor dispersion affects the overall performance of a speaker! Some speaker companies think that they can use a directional (read: "large-diameter") midrange driver and a small-diameter dome tweeter and solve the dispersion problem, but this isn't true. Much of the power response energy is in the midrange and lower treble.

I would love to learn the story on your IC20 acquisition. Where did you find them and so forth....

--Tom

[Howard Ferstler]

Yes, Howard has been on quite the journey with that pair of his.

I do take my hat off to him for his amazing woodworking ability and his rather interesting approach to the image control problem.

He has also changed with his listening taste in recent years, now being a fan of mainly the "focus mode" inner panels mainly. Although with his latest incarnation, the inner panels run full tilt with nothing at all going to the outer panels.

In "stock" form, there is always some output to the opposing panels, though greatly reduced. Always, the output of the system (stock) is the same though shifted.

For myself, the whole thing is moot, because I never cared about the image control aspect of the loudspeaker. Only that they would play in "Omni" mode.

With the power to the modules switched off, the speakers always remain rock solid with full continuity to all drivers.

Bill

Yes, in the focus mode the attenuated panels are playing so low in level that it is impossible to accurately measure their contributions. The wrap-around sound from the louder panels, cabinet shading notwithstanding, simply overwhelms them. Their output is basically inconsequential as best I can tell. With my new, dual-crossover arrangement the outer panels can be (1) turned completely off, (2) attenuated by one to two dB, or (3) attenuated by perhaps 6 dB. The second assumption is based upon what Roy got with his Model One attenuations. The third is basically a guestimate on my part, since, as I noted, it is impossible to accurately measure the level of the attenuated panel without the output of the louder panel skewing the results. Up close you can definitely tell the differences in the panel outputs, but things get dicey as you move out further and get to the prime listening locations.

I have listened to the speakers in the "stereo" mode of my system (surrounds and center turned off) and the difference between the now pseudo-omni mode (outer panels down 1 or 2 dB) and either of the other modes (completely off or down about 6 dB, as per my estimate with the latter) is surprisingly slight. You get a tad better detail and focus with the focus mode (needless to say, and this will depend upon room size/shape and sidewall materials), but somewhat, although not overwhelmingly so, better spaciousness with the outer panels running nearly full tilt (with room size/shape and sidewall materials again having an impact). The 6-dB down setting splits the subtle differences.

However, once the surround and center channels are engaged all bets about stereo performance, soundstaging and imaging and clarity are off. the differences, especially involving spaciousness, become slight, indeed, and even the detail and focus differences become less apparent, due to the impact of the MTTM vertical array on the center speaker.

The more speakers you have in a system the more things tend to blend together into a systematic whole. I rather like it that way.

Howard

Howard

[newandold]

Bill,

"Another thing: the treble dispersion on the IC20 is so outstanding that the integrated acoustic-power output is better than almost any other speaker, and therefore the high-frequency output into the reverberant field would more than offset the slight attenuation that might be occurring at the frequency extremes! Yeah, perhaps that last half-octave in the 15-20 kHz region is down a bit on axis, but the power response is probably ruler-flat out to at least 15 kHz, so what's not to like about that! There are any number of exotic speakers with great "imaging" and ruler-flat on-axis frequency response in the direct field that would fall flat (no pun intended) trying to put energy into the reverberant field. Poor off-axis performance assures that a directional speaker that sounds "spacious" and "3-dimensional" in the direct field, toed-in pointing to the listener a few feet away, will almost always sound dull and lifeless once that listener moves back into the room's reverberant field. It is amazing how much poor dispersion affects the overall performance of a speaker! Some speaker companies think that they can use a directional (read: "large-diameter") midrange driver and a small-diameter dome tweeter and solve the dispersion problem, but this isn't true. Much of the power response energy is in the midrange and lower treble."

Beautifully stated, Tom, and covers most of why I've been a fan of the A1, which shares most of this in addition to the IC.

"I would love to learn the story on your IC20 acquisition. Where did you find them and so forth...."

--Tom

Oh yeah, I will tell it again here (added to my original post)

From my first introduction to the IC from RA himself in 87 or 88?

To my rental truck in 2012!

In a few days.....

Bill

[Howard Ferstler]

Hey Tom,

I want to take a step back with regards to Howard's IC's and point out what got him started (at least my understanding) doing any modifications to his speakers at all.

Who knows how many years ago, the image control modules on his units began to act up and shift all over the map from one mode to the other.

With no "fix" coming from Allison Acoustics on this, Howard pulled all that from the system and just hard wired the things into Omni, wanting to get everything out of all drivers, all the time. Quite a contrast to where his head is now, but back then, quite different.

I would bet the farm if the IC modules proved to perform flawlessly as advertised, he would never have done anything to those systems, except to maintain and enjoy.

Bill

The IC feature malfunctioned right out of the box. One or the other speaker would suddenly switch a panel on or off, and nothing I did (or what Roy suggested I do) fixed things. I even taped over the sensors on the fronts of the cabinets. I checked the schematic and there was one 1500 pfd capacitor in there that had me suspicious. (Its sole function, being hooked between the two G terminals in the IC-switching network, was to keep the 12-volt feed to that network from negatively interacting with, I believe, the tweeters.) If one looks at the schematic it can be seen that its insertion was an afterthought that resulted in some post-production problems. Whether or not it was the problem (probably not, since each system had one and the chances of both being defective were slim), there was a problem and after a while, since the omni mode was my prime listening requirement at that time, I figured that I could just hard wire things and stop worrying about sudden imaging shifts in the middle of a listening session.

Prior to opting for my latest dual-network solution I spent some time with the systems hard wired to the focus mode, and it did not take long for me to realize that I wanted the switching functions back. Hence, those much more extensive mods done recently.

Incidentally, Bill, I still have one of the IC network wall-wart power connectors for the systems, and it is possible that somewhere in my collection of old audio gear I have the remote switching hand-set too. If you hunger for either, let me know. I can at least surely supply the wall wart. All bets are off with that controller, however.

Howard

[Howard Ferstler]

Hey, I am back.

Here is some poop on those IC-20s of mine. The IC circuit switching acted up almost from the beginning and I finally decided to hard-wire the things into the omni mode and leave it at that. I gutted the IC network, and removed the sensors and lights on the front, covering the holes with a small brass plaque that says "Allison." This was my first mod and I could pull it off, because I had the crossover and IC schematics, courtesy of Roy.

The second mod, done some years later, was a complete rebuild of the crossover network, following the factory specs. This involved replacing the old, back-located crossover mount with standard 5-way binding posts and rebuilding the network (new caps, new resistors, same chokes) on a triangular-shaped board that was screwed to the interior bottom of the cabinet. While the original cap arrangement had some poly jobs for the mid and tweeter sections and one standard non-polarized job for the woofers, the replacement caps I used were all poly types, including a physically huge one for the woofers. Because the new network used up some space at the cabinet bottom, the original reversed woofer tube would no longer fit, and so I re-configured the woofers both facing forward, just like with the Model One. Because I use outboard subwoofers for the frequencies below 80 Hz the modest increase in even-order distortion caused by this change would be meaningless. More on the subwoofers, below.

However, now I have even more substantially modified my IC-20s, basically installing TWO crossover networks into each. The original network had to kind of split the difference in terms of choke and capacitor values, because it had to sometimes handle both four tweeters and four mids (omni mode) and at other times handle just two of each, with only a modest amount of feedback from the greatly attenuated other-panel drivers (focus mode). This works OK, because of the wide coverage capable from the mid and tweeter drivers, but it actually was not as perfected an arrangement as Roy got with either the Model One and Model Two units, or the Model 9 and CD-9. Those have the crossover chokes and caps precisely aligned with the fixed driver loads.

Yep, two separate networks in each system.

The one for the inner panels is similar to the version in the Model One: two tweeters, two mids, two woofers; and with some subtle changes (slightly different series choke and capacitor values) to compensate for driver aging with the midranges, plus going to second-order filtering for the tweeters to protect them better than what was possible with the first-order filtering of the Model One. (Note that the factory IC-20 also used second-order filtering for its four tweeters, as do all of the CD and AL series systems.)

The outer panels each have their own crossovers (mounted on still another board and screwed to the interior rear of the cabinet, just above the binding posts), with the parameters similar to the mid/tweeter sections of the inner panels. The mid-tweeter panel networks are wired in parallel (each is nominally 8 ohms, like a Model One, with parallel wiring delivering nominally 4 ohms), and the outer panels can be turned off with 20-amp-rated switches. No changes were made to the networks for the woofers, which run together full time.

Both panels have their driver complements fully protected by a total of FIVE polyfuses, each sized for the loads involved. The original IC-20 had three.

Further mods involved some additional switch work. The inner panels have permanent resistors installed in their networks and those resistors partially mimic the "concert-hall slope" Roy made possible with the Model One's own switching option. The slope chosen for the inner panels was somewhat between Roy's full slope and the less aggressive middle slope. The outer panels use slightly larger contouring resistors, given them the full-slope contour. This means that the outer panels play one or two dB less loud than the inner panels when they are turned on.

An additional switch for each outer-panel section allows the option to drop the output of the turned-on outer panels about 6 dB lower than the inner panels, kind of splitting the difference between the focus and omni modes. Finally, two additional switches allow the user to decrease the output of any of the panels in operation several dB in two stages. Because of impedance differences seen by those switches when either the inner or outer panels are in operation they offer up different attenuation amounts. With just the inner panels working each switch uniformly drops the mid/tweeter output by roughly 2 dB. With both panels in operation each switch uniformly drops the id/tweeter output by roughly 4 dB. These attenuations do not change the slopes of the contouring; they just change the mid/tweeter section outputs in relation to the woofer outputs below 350 Hz. The switches used for this additional contouring and shaping are also 20-amp rated jobs, and I do not expect them to develop oxidation problems.

Most members of the Allison group I belong to know that I also employ flanking "ambiance" speakers, with a pair of side-wall mounted Model Fours each 30 inches away from the front wall and sitting on 5-foot high bookcases (these Fours are also modified to pretty much mimic what Roy did with the Model Four he designed for the Kentucky people) and a pair of Model Eights (modified to mimic the network behavior of the later CD-8) at the same height and on identical bookcases flanking the listening couch further back into the room. The output levels of these four surround speakers are MUCH lower in level than what we get with the standard Dolby set-up parameters, because it is their job to add a comfortable amount of simulated hall ambiance to the classical and baroque music I listen to the most. In my case they were initially set and then modified by the program in my mid-grade Pioneer receiver. I use the Dolby "height" mode to deal with those more forward surround speakers. I can leave the receiver settings fixed, because this installation is used for music listening only.

This package also has a single, floor-standing center speaker (38 inches tall, with an angled-back slightly front panel) that uses Allison mids and tweeters in an MTTM vertical array, with a single Model Four woofer. The crossover network for the mids and tweeters is identical to that for the inner-angled panels of the IC-20s, with the woofer network mimicking what we have with the CD-9. I built the cabinet myself out of thick, solid cedar and MDF. The grill is a cut-down IC-20 grill. It has no level controls, and it is set to operate about 2 dB below the standard Dolby set-up level.

The installation also has two subwoofers: cylinder types, 68 inches tall, 14 inches in diameter, with Dayton Reference drivers, and with power coming from a Crown XLS1000, 350 wpc power amp. An ART equalizer contours the sub outputs below 80 Hz.

This arrangement with the IC-20s allows me to both shape the radiation pattern of each system from wide (but favoring the inner angles) to the usual, dual-panel super-wide pattern, and to adjust brightness levels when faced with recordings that are a bit too brittle sounding for my taste. Most of the time I run just the inner panels, plus the center and surrounds, with the slope adjustments turned off.

This is a lengthy description of what I have done, following parameters set up by Roy long ago and not wildly experimental, but with some changes that are related to driver aging.

If anyone is interested I can post some photos, at least once I figure out how to do it.

Howard Ferstler

I need to footnote my own commentary.

One other mod I did recently was to insert an 8.2 mdf capacitor in parallel with each of the tweeter ballast resistors in all four networks (4 ohms in the inner panels and 6 ohm in the outer panels), as well as tweeter 4-ohm ballast resistor in the network within the center system I built. Thpse ballast resistors basically pad down the output of the tweeters (similarly to what we get with the tweeters in the Model One), but if one inserts a proper capacitor in parallel with that tweeter, as the frequency climbs the resistor begins to become bypassed and so the current flowing to the tweeter increases. This ramps up its output as its native output tends to roll off. My mod increased the output gradually above 8 kHz, reaching a maximum of +2 dB at 10 kHz and +4 dB at 12.5 kHz.

Now, this may sound like a crank move on my part, but Roy actually did something like that with the resurrected Model Four he re-designed for the Kentucky outfit. He inserted a 12 mfd capacitor in parallel with that tweeter network's 2-ohm ballast resistor in order to get those tweeters to be a bit more impressive in the top octave. I used the 8.2 ohm cap because the tweeters seemed to be rolling off above 8 kHz more than they did when they were newer.

I frankly think that both his and my "updates" would have zero impact for old guys like me, but it would certainly impress product reviewers who measured those systems and marveled at how they were potently flat right out to hypersonic frequencies.

I did it on a lark, and would do it again.

Howard

[newandold]

The IC feature malfunctioned right out of the box. One or the other speaker would suddenly switch a panel on or off, and nothing I did (or what Roy suggested I do) fixed things. I even taped over the sensors on the fronts of the cabinets. I checked the schematic and there was one 1500 pfd capacitor in there that had me suspicious. (Its sole function, being hooked between the two G terminals in the IC-switching network, was to keep the 12-volt feed to that network from negatively interacting with, I believe, the tweeters.) If one looks at the schematic it can be seen that its insertion was an afterthought that resulted in some post-production problems. Whether or not it was the problem (probably not, since each system had one and the chances of both being defective were slim), there was a problem and after a while, since the omni mode was my prime listening requirement at that time, I figured that I could just hard wire things and stop worrying about sudden imaging shifts in the middle of a listening session.

Prior to opting for my latest dual-network solution I spent some time with the systems hard wired to the focus mode, and it did not take long for me to realize that I wanted the switching functions back. Hence, those much more extensive mods done recently.

Incidentally, Bill, I still have one of the IC network wall-wart power connectors for the systems, and it is possible that somewhere in my collection of old audio gear I have the remote switching hand-set too. If you hunger for either, let me know. I can at least surely supply the wall wart. All bets are off with that controller, however.

Howard

Hi Howard,

I remember your story quite well as we have talked about it.

Before I get started, I would like to thank you for that very gracious offer (the "wart").

So far, the one I use (to run both) is working just fine.

If I get into trouble, I will let you know.

I guess I got lucky, and my image control system stays put MORE than well enough to enjoy a listening session in any mode.

Overall, I just find the experience to be rather unremarkable, compared to "steering" as you like to put it, with the center channel.

Therefore, the wall toggle that I have that wart plugged into, stays off, except for "demo" purposes. It's always fun, when I have the right captive audience, to explain the history of things, and then just shut it off.

You know, I never asked you before, but you never did have trouble when you were de-powered to the default Omni, did you??

Now all that being said, one of these days I will get the dedicated line with its own neutral and isolated ground installed and try a grounded wart 3 prong of the same electrical value, just to see if that combination solves that problem. (I still maintain it is an "external" rather than invasive problem.)

If not, I have that additional circuit in the room that I want added in there anyway.

Bill

[newandold]

Hi All,

Just wanted to get started here at The Classic Speaker Pages.

My story is almost 3 yrs old now and has posted on another forum, but I believe this is a better place to continue and enhance the discussion of Allison Speakers in general, so anyway here I am.

During the coming weeks I would like to revisit that story (from my topic thread) here and just generally, continue the discussion of "anything Allison" here in a more secure web space, along with these other fine classics!

Regards,

Bill Mina

25 YEARS LATER

ACQUIRING THE ALLISON ACOUSTICS IC-20 LOUDSPEAKER SYSTEM

………It was around 1987 when I learned of the IC 20, quite unexpectedly.

10 years prior, I had bought the Allison:One, after a demo that I don’t think lasted 3 minutes, in a place that no longer exists (Harvey Sound). The demo room was too small, and I heard the speakers from off to the side, way out of the “sweet spot”. Regardless of where I stood, that sound! Where do I sign, are they in stock and how the hell am I going to fit them in the car.

Back to 1987, I needed a midrange driver for the A1’s and called into Allison, in Natick Mass. I had the pleasure of speaking to RA himself on the phone.

Cheerfully, I admit having a propensity for playing my stuff a bit on the loud side and that subject came up in my conversation with Roy, while ordering the midrange.

During that call, Roy said to me:

Well, you might want to consider the New IC-20 loudspeaker we’ve introduced (his words, more or less). And with that, he sent me a brochure, along with my replacement driver.

First impressions……. when I opened that product brochure:

The beautiful finished wood behind the grilles, the cool led lights, screen protected drivers and the absence of the brass pins that I was no fan of. I could not process that “backwards” woofer yet, but it would become clear soon enough.

It looked like just what it was.....a highly developed and refined larger version of the A1.

I paid 750 for my ones years ago and I am now married with a 5 year old. 5000 bucks…..? I could barely afford to pay for that midrange in those days as a self-employed businessman, Let alone go for an upgrade like that. I was happy enough with The A1’s and just let the whole thing, go (but never forgot).

Fast forward now, 13 years later and I am busy integrating my now 24 year old A1’s into a home theater layout (my business was good). By then, Allison was gone and David Faulkner was in the middle of his ill fated venture. He was quite helpful to me and I bought the 2way Allison speakers, that remain part of my system from his inventory. Poor David, he is a very nice guy, but was gone in almost no time.

Now I’m committed to a home theater system, with loudspeakers that have gone out of production twice. That means EBAY for spare drivers to keep the fleet running. I’ve kept a worldwide search going for anything Allison Acoustics, ever since.

That led to 3 or 4 pair of IC 20’s come up for sale between around 2001 and 2012. My thoughts have come back to buying a pair, IF they are the right ones.

For anyone who doesn’t know, here is some more information (not a direct quote) directly from Roy Allison himself from a communication I once had with him, regarding how rare these things are:

…….100 IC-20 cabinets were ordered from the cabinet manufacturer for the first units to be produced. Several of those had defects leaving them unsuitable for production……

That was it. Whatever IC’s exist are from that first (and last) cabinet order.

Let me go right to the auction. Below is a copy of the Description that Valerie C. (wonderful seller), posted:

“Finally, I have had help in moving my largest pair of speakers out into a space where I could photograph and list them - at 100lbs each without the boxes these are some serious loudspeakers. First I have to apologize that although I took a lot of photos of the actual speakers I forgot to download them so I will be adding these in the next day. The photos shown at present are of the brochure that will accompany the speakers.

These are truly amazing and anyone who knows of Allison speakers will appreciate just how good these are. Mine are in their original boxes and actually are the first pair handmade before they went into actual production. The cabinets are slightly darker than shown in the picture with the grilles removed, they are actually oiled walnut. I used to have these in my living room about 17 years ago and they are great! For the past 17 years they have been stored in a dry basement in their original boxes and with the original packing materials. There is no sign of physical wear on either unit.

The specs are as shown in one of the photos. Each speaker contains 2 x 10" woofers, 4 x 3.5" mid range units and 4 x 1" tweeters. As you can appreciate because of the size and weight, I am not shipping these. They can be collected personally or by the buyers own arrangements and I will do my best to assist with this.

Any questions? Please feel free to contact me. I will be posting other consumer electronics in the coming days. I am having a very hard time adding new photographs to this listing. If you are willing to give me your email address contact me via the 'Contact Seller' tab and I will happily send you these photos.”

So here I am, 25 YEARS after talking to Roy about the “new” IC20, having a chance at buying and owning the very first pair that had been built.

This was the pair I would get provided there wasn’t another bidder out there with a bigger screw loose than mine was.

I won the auction and have been sitting “pretty” since 2012.

The serial numbers are 001A and 000B……so it goes!

Bill Mina

[newandold]

"I would love to learn the story on your IC20 acquisition. Where did you find them and so forth...."

--Tom

Hi Tom,

I posted my "acquisition" story

I did forget to include the location, which was in Mass. about 32 miles or so away from the Plant in Natick, ironically.

A full day round trip with the rental truck!

Bill