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AR 3a use with new AV receiver


Jackeroo

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I'm reworking my audio and just discovered that I've been running my AR 3a's with a Yamaha AV Receiver (RX-V1600) and just found the notation at the speaker connections for 6 Ohm to 8 Ohm min. I know WAY too little to know the consequences of continued use (receiver failure? speaker failure?). Can the speakers run in series and will that "cure" any problems? Reciever rated for 120 W RMS @ 8 Ohms, but there is also a listing for "Dynamic Power (IHF)" with the following notation: 8/6/4/2 Ohms...........155/195/250/330 W. I'll also be doing some work to repair the potentiometers so stand by. Thanks for ANY help.

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The receiver will have circuit protection that cuts in when an unsuitable load is used. Some receivers will allow operation with loads outside the specified ranges and just cut out when it becomes dangerous, but others will cut out the moment they detect that the load is outside the range.

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Frankly I wouldn't risk it. AR3a is nominally 4 ohms but at some frequencies goes even lower. A/V receiver amplifiers generally in my experience also don't have the power bandwidth to drive speakers at the lowest audible octave, a capability that is one of AR3a's remarkable strengths. Often they cut off at 50 hz although the LFE output to an outboard subwoofer amplifier probably goes to 20 hz or lower. (check the specifications for your receiver's frequency response and power bandwith to find out.) The best advice is to choose an amplifier more suitable for this difficult to drive electrical load. The sound quality makes it worthwhile. One suggestion many have found satisfactory is Adcom GFA 555. There are many others.

Gene pointed out that modern A/V amplifiers have protective circuits to prevent damage when subjected to conditions they were not designed for. Still it's not a good idea to test it to see if it works.

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Soundminded--the Yammy is a sophisticated surround-sound receiver, so the old Adcom stereo won't cut it. If Jackeroo is willing to pony up for a new surround sound receiver, I recommend Onkyo. My TX-NR1008 is definitely rated for 4 ohm loads and I'm sure other Onkyos are as well.

Jackeroo--I've seen stuff on the 'net like this http://www.yamaha.co...EV_RX-V2400.pdf that says you can use 4 ohm speakers with your Yammy, but what does he know? Have you tried contacting Yamaha tech support?

Kent

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There probably is a good middle ground. If this is a higher-end Yamaha, then it will likely have pre-outs for the LCR and SR channels. That means that you could use the LR pre-out jumpers to bypass the Yamaha's internal LR amp section and feed its LR pre-amp signal to an external power amplifier of better quality--like the Adcom or another good amp of your choosing.

I'd agree that Onkyo equipment tends to be better with low-impedance loads than most AV receivers, but I had a very good Onkyo av receiver about 2 years ago (forgot the model number, but it listed for $1200 and was rated at 135 x 7, RMS), and it didn't do justice to my AR-9's. And that was when the Onkyo was set to the 2-channel mode, so there were no other demands on its power, nothing to degrade its "attention" to the 9's.

So, I sold it and reverted to a 2-channel system, with a 400 WPC RMS Parasound power amp and pre-amp. No comparison.

I think if you utilize the Yamaha's pre-out function to upgrade your front-channel LR amp with an external amp of good quality, you'll do everything you want: do justice to your very low-impedance 3a's, not endanger your Yamaha, and preserve your surround sound capability.

Steve F.

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Good point Steve. Although I use the Onkyo for home theater, that set-up does not include the AR3a's. Those are driven in stereo by a MAC4100. Using the pre-out for just the front L & R sounds like a perfect solution. Maybe use one of those new Crown amps that have been praised in these pages. Lots of bang for the buck.

Kent

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It's pretty rare to find HT receivers that will handle speakers with impedances under 6 ohms. A few years back when I was shopping mine, the only ones I could find that officially supported them were the two or three top models from NAD and Onkyo. Harman Kardon's servce dept gave me the numbers of some of their HT receivers that were not officially rated for 4 ohm or lower speakers but would work with them if they had VERY good ventilation to avoid heat that would trigger their protection circuits. HT pre-pwr sets or receivers with pre-outs feeding separate power units definitely opens up your options a lot.

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See page 32 of the Yamaha RX-V1600 Owner's Manual, available here: http://usa.yamaha.co...__u/?mode=model (under "support" tab) for instructions on connecting an external amp.

Tom Tyson recommends the Crown XLS-1000 as a bargain, delivering 350 watts/channel into 4 ohms. See post #68 here:

http://www.classicsp...h=1

Kent

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This may sound like heresy to AR3a "purist" but would you consider adding a subwoofer ? The 3A's does go low but is no match for a dedicated powered sub. You can take the signal from the reciever's pre-out and "high pass" the signal using an electronic crossover, then feed this signal back into the reciever. The reciever would then be "coasting along" since it doesn't have to "see" the 2-3 ohm impedance the 3a's present at very low frequencies.

Using this approach retains the 3'a's original tonal balance from the mid -bass on up, while the powered sub can deliver the deep bass at levels probably louder, cleaner, and possibly even "lower" than any "stand-alone" AR 3a /amplifier combo).

I used to own 3a's and the amplifier I used was a Dunlap-Clark 1000. It was capable of 800 watts/channel into 2 ohms. But it weighed 70 pounds !

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Gerry, guess I'm a heretic.

In the mid '80s I bought a VMPS original sub in kit form. It has a 12" woofer and 15" passive radiator. Back then I used it with Allison: Fours in my 1st surround sound system (had Minimus 7s in the back). It gathered dust for awhile in the 90s, then I replaced both the woofer and the PR with original replacements from VMPS (did not know about refoaming at the time). In the '00s I added a plate amp from Apex Jr and used it with AR2ax's. When I got the AR3a's I again retired the sub, but later thought "why not?" So now it's back in the vintage stereo (no surround) system, crossed over at 60 Hz to augment the AR3a's. Nice.

Kent

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A few questions:

Was the VMPS sub non-powered in its original form? You remarked that you "added a plate amp from Apex Jr." What power? Did the plate amp have any LF EQ built into it or was that customized by you? What (if any) LF EQ did you use with your VMPS sub and how did you determine the amount/shape of the EQ curve?

Is the sub running in conjunction with the 3a's below 60 Hz or are the 3a's high-passed at 60 Hz and the VMPS is running alone below 60 Hz?

There are pluses and minuses to doing it both ways. If you listen to a lot of material at high levels with substantial content below 35-40 Hz, that could strain the 3a's, as they are not designed to deliver 21Hz exploding death star sound effects at 105dB theater-like levels. Assuming the VMPS can handle those duties, you'd be better off with that doing LFE duty alone.

However, the other side of the coin is this: If you don't listen at extremely high SPLs (and therefore your listening habits don't endanger your valuable 3a's), you will get a much smoother in-room deep bass response by having three deep bass sources (both 3a's and the sub), each one with a different dimensional relationship to the various reinforcing room boundaries. The left 3a has its dimensional relationship to its nearby walls and floor, the right 3a has its, and the VMPS sub has its own set. That will stagger the positional effects of the bass, greatly reducing the liklihood of destructive bass resonance modes occuring in your listening room.

Curious as to how you use the equipment and what your set-up is/how it was determined.

Steve F.

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Steve,

Apparently all VMPS subs are passive. There is a rationale on their website: http://vmpsaudio.com/loudspeakers/subwoofers/

Years ago I used a very fancy setup, with a Richter Scale active crossover and a bridged Hafler 220 to drive the sub. Then I went through a period of downsizing, got rid of all the separates and bought a receiver. That's when the VMPS was just collecting dust. Then several years ago I bought this plate amp: http://www.apexjr.com/Apexsenior.htm I liked the remote control function.The low pass filter is built in and is adjustable, so whatever cut-off I use, the main speakers (in this case 3a) do not go down below that point. The VMPS is virtually flat down to 20 Hz IIRC.

Kent

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check out the receivers specs. If the wattage is rated at 40 to 15,000 hz you will not fill out the bottom end of the 3as bass, but if the specs are like my power amp 150 watts per channel at 8 ohms 5 to 25K you will have full power at low frequencies. most modern receivers are speced at 40 hz as the bottom end and that will not do justice to ar 3a,s 9s and 90s.

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A few questions:

Was the VMPS sub non-powered in its original form? You remarked that you "added a plate amp from Apex Jr." What power? Did the plate amp have any LF EQ built into it or was that customized by you? What (if any) LF EQ did you use with your VMPS sub and how did you determine the amount/shape of the EQ curve?

Is the sub running in conjunction with the 3a's below 60 Hz or are the 3a's high-passed at 60 Hz and the VMPS is running alone below 60 Hz?

There are pluses and minuses to doing it both ways. If you listen to a lot of material at high levels with substantial content below 35-40 Hz, that could strain the 3a's, as they are not designed to deliver 21Hz exploding death star sound effects at 105dB theater-like levels. Assuming the VMPS can handle those duties, you'd be better off with that doing LFE duty alone.

However, the other side of the coin is this: If you don't listen at extremely high SPLs (and therefore your listening habits don't endanger your valuable 3a's), you will get a much smoother in-room deep bass response by having three deep bass sources (both 3a's and the sub), each one with a different dimensional relationship to the various reinforcing room boundaries. The left 3a has its dimensional relationship to its nearby walls and floor, the right 3a has its, and the VMPS sub has its own set. That will stagger the positional effects of the bass, greatly reducing the liklihood of destructive bass resonance modes occuring in your listening room.

Curious as to how you use the equipment and what your set-up is/how it was determined.

Steve F.

Of all the "research" Floyd Toole did, the only contribution he made as far as I can tell to the technology of audio as opposed to the technology of market research was finding that the most uniform bass response in a small room requires four subwoofers located in the corners of the room or on the midwalls of the room. Experience with AR9 and other very low frequency reproducers convinces me that with only two very low frequency sources the bass level can vary condiderably from one point in a room to another even only a foot or a few inches away. Generally the closer to the intersections of the walls/floor you get, the louder the deep bass becomes, just as for speaker placement. The research findings are explained on Harman's web site.

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I can vouch for Steve F's comments about bass response and woofer/ listening placement. EXTREMELY challenging to get "smooth" bass response for any given set-up. There are at least SIX "inter-dependant" variables determining bass uniformity, extension and loudness. In no particular order of "importance": Room Dimensions, Room Construction, Speaker Placement, Speaker Characteristics, Listener Seating Positioning , Electronics’ Capabilities/Settings and Source Material.

Kind of an acoustical analogy to getting Rubik’s Cube solved perfectly and easily. Changing just ONE of the above variables PROFONDLY affects what the listener experiences in its totality. Complicating things more: changes/differences in low frequency characteristics affects how we perceive midrange/treble "accuracy". And this is BEFORE we tackle the subject of "room treatment" and the aesthetics of it all (most of us "listen" with our EYES too, whether we know it or not) !

Dozens of distinguished audio professionals over several decades have written about this. An equal amount of "solutions" have also been developed. But I've yet to find a universal, easy, quick-fix, cost -effective, user friendly, aesthetically pleasing, space saving "plug and play" device that can do this. Which makes being an "audiophile" simultaneously rewarding, challenging and frustrating...like being married (or single)...LOL.

BTW... I've tried two pairs of AR 3a's wired in series and found it VERY unsatisfying. What I remember: a drop in perceived overall loudness coupled with LESS bass, not to mention comb - filtering in the mid to high frequencies caused by different arrival times from multiple midrange /tweeter locations .

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Wish "spell check" could be incorporated into this format/response... can't type or write to save my life !

You can install spell-check browser plug-ins that will work in forum posts.

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You can install spell-check browser plug-ins that will work in forum posts.

Or use Firefox. Nice browser and has spell-check

Kent

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Well, I did my own spell-check using Word and "copy & pasted " it above. But the reason I'm posting again is the subject of wiring 2 pair of AR3a's in series to mitigate low impedance problems in the bass fequencies when used with "mid-level" electronics.

I stated that I found this method unsatisfying from a performance standpoint: Reduced SPL, less bass, and weird overall frequency response. But why? Intuitively, you'd think this would work. Here's my theory why it didn't (as least for me).

The low frequency impedance of a SINGLE AR3a can go as low as 1.3-1.5 ohms, depending on unit to unit manufacturing tolerances. It's also a REACTIVE load; not a simple "resistor". With capacitive and inductive elements, impedance at low frequencies isn’t anything like a simple "resistor" that most amps are rated at. So, mid-level amps usually go into "protection mode" and/or sound "wimpy" when a single 3a is played "loudly".

Impedance at frequencies ABOVE "the bass problem area" of TWO AR3a's wired in series goes as high a 20-30 ohms (I'm approximating here), which is like an "open circuit " to the amplifier. I believe that explains the drop in level.

Simplistically put: If a single light bulb consumes "X" watts to produce "x" lumens for any given room, then increasing(doubling)the size of the room must DECREASE the amount of lumens that same lightbulb can illuminate(loudness).

Most amps deliver there maximum voltage into 8 ohms BUT maximum current into 4 ohms (I'm talking resistive ohms). The majority of loudspeakers have impedance characteristics that match well with entry to mid-level amps. The AR3a impedance is such that only VERY rugged amps that can deliver both high voltage and high current SIMULTANEOUSLY can do the AR3a "justice" when played "hard".

There ARE speakers other than the AR3a that can also play "low" and "loud". But,they MUST be much bigger and /or complicated to do so. No free lunch in the area of box size vs. sensitivity vs. bass extension.

Lastly, from an aural perspective, to double PERCIEVED "loudness" requires a SIX to TEN time increase in available "watts" the amp must deliver. To play a single pair of AR3a's "to the max" requires beefy (heavy and costly) amps. No way around it!

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Well, I did my own spell-check using Word and "copy & pasted " it above. But the reason I'm posting again is the subject of wiring 2 pair of AR3a's in series to mitigate low impedance problems in the bass fequencies when used with "mid-level" electronics.

I stated that I found this method unsatisfying from a performance standpoint: Reduced SPL, less bass, and weird overall frequency response. But why? Intuitively, you'd think this would work. Here's my theory why it didn't (as least for me).

The low frequency impedance of a SINGLE AR3a can go as low as 1.3-1.5 ohms, depending on unit to unit manufacturing tolerances. It's also a REACTIVE load; not a simple "resistor". With capacitive and inductive elements, impedance at low frequencies isn’t anything like a simple "resistor" that most amps are rated at. So, mid-level amps usually go into "protection mode" and/or sound "wimpy" when a single 3a is played "loudly".

Impedance at frequencies ABOVE "the bass problem area" of TWO AR3a's wired in series goes as high a 20-30 ohms (I'm approximating here), which is like an "open circuit " to the amplifier. I believe that explains the drop in level.

Simplistically put: If a single light bulb consumes "X" watts to produce "x" lumens for any given room, then increasing(doubling)the size of the room must DECREASE the amount of lumens that same lightbulb can illuminate(loudness).

Most amps deliver there maximum voltage into 8 ohms BUT maximum current into 4 ohms (I'm talking resistive ohms). The majority of loudspeakers have impedance characteristics that match well with entry to mid-level amps. The AR3a impedance is such that only VERY rugged amps that can deliver both high voltage and high current SIMULTANEOUSLY can do the AR3a "justice" when played "hard".

There ARE speakers other than the AR3a that can also play "low" and "loud". But,they MUST be much bigger and /or complicated to do so. No free lunch in the area of box size vs. sensitivity vs. bass extension.

Lastly, from an aural perspective, to double PERCIEVED "loudness" requires a SIX to TEN time increase in available "watts" the amp must deliver. To play a single pair of AR3a's "to the max" requires beefy (heavy and costly) amps. No way around it!

Setting aside for a moment that the amplifier's effective electrical damping factor will be below 1 the problem stems from the fact that the electrical impedance of the two speakers is not the same at all frequencies. Therefore the FR of one speaker will be different from the other. If the two were perfectly matched at all frequencies there should be no difference in the sound. The closest practical approach to this problem is to set both tweeter and midrange controls on both speakers to maximum and use a graphic equalizer to adjust the spectral balance.

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I used to own 3a's and the amplifier I used was a Dunlap-Clark 1000. It was capable of 800 watts/channel into 2 ohms. But it weighed 70 pounds ! . . .

Lastly, from an aural perspective, to double PERCIEVED "loudness" requires a SIX to TEN time increase in available "watts" the amp must deliver. To play a single pair of AR3a's "to the max" requires beefy (heavy and costly) amps. No way around it!

Gerry,

A couple of thoughts: The AR amp was designed to power AR speakers, including their flagship 3a. That amp put out 60wpc into 4 ohms. I agree that more power is better but you may not need the behemoth you described. Tom Tyson has written about the Crown XLS line and while I have not tried them I would respect Tom's judgment. The XLS1000 is rated 350wpc into 4 ohms, weighs less than 9 pounds and costs about $300.

At the upper end of the range, the XLS 2500 delivers 775wpc into 4 ohms, weighs just a tad under 11 pounds and can be found for under $500.

So maybe there IS a way around it. As I said, I don't own a Crown and have not heard it, but from what Tom says this is a great solution for our power-hungry speakers.

I've been using a MAC4100 which is rated 100wpc into 4 ohms, and it's certainly no slouch. But I'm intrigued by the idea of using, say, my recapped Advent 300 as a preamp/tuner with a Crown for power. Or maybe my minimalist DB systems preamp with a Crown.

So many tempting choices! :D

Kent

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The AR amp was very conservatively rated, and there are several accounts of units going through the old McIntosh amplifier clinics and coming out with test results in the 70-80 wpc range.

I'm feeding my 3a/2ax/1ms HT setup with an older Sherwood 5-channel pre/power pair that is FTC rated at 170 wpc, and haven't really felt the need for any more power. Maybe if I ever get a pair of 9s...

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When I first got into "hi-fi" in my teens, the mags that I read was Stereo Review, High Fidelity, and Audio Magazine. What I noticed was all three magazines stated at one time or another in some article or another that the "average room size" was 2000 to 2500 cubic feet (L X H X W). Having lived in Boston most of life while pursuing my hi-fi passion , I rarely listened in rooms that large. Even the "well-heeled hobbyist" I've encountered over the years llistened in rooms considerably smaller than that "average". I think most audio enthusiast also live in rooms smaller than 2500 cubic feet. That said, one doesn't really NEED lots of power to deliver "loud" playback levels. But "loud" compaired to what ?

What I often heard to be the "standard" for "realistic" playback levels was the following: playing well recorded symphonic recordings with high dynamic range should yeild between 100 to 105 PEAK SPL. The "average" SPL is much lower (around 75 db), which is why the AR amp (I owned one as well) could do well with 3a's IF the room wasn't very large, the bass extremely deep and/or sustained, and the "peaks" not very frequent. When "audiophile recordings" and CD's became the norm, THAT'S when the typical AR3a / reciever gets over-loaded. Reproduceing "peaks" from 100 db to 106 db represents a four-fold increase in "watts" derlivered.

So, depending on the source material and the other variables mentioned above, "adequate power" can range from 20-50 watts / channel to about 500 watts or more / channel. I've never owned the modern high-powered, "light-weight" amps of today. But I'm curious as to how they would SOUND if one was to instantainiously switch from one amp to another playing back "demanding" materia (especially in the deep bass) !

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I've never owned the modern high-powered, "light-weight" amps of today. But I'm curious as to how they would SOUND if one was to instantainiously switch from one amp to another playing back "demanding" materia (especially in the deep bass) !

The FTC power rating introduced in the 1970's was watered down a bit by the elimination of the max power warm-up requirement. It also only applies to stereo amps, though most reputable HT manufacturers will provide FTC ratings in stereo mode along with their all channels ratings. If an amp or receiver doesn't come with an FTC rating in stereo mode, a good rule of thumb is to take its all channels RMS rating and divide by 2, and if it only comes with "peak" ratings, divide by 4. AND some disreputable manufacturers will claim total watts rather than wpc. So a low end 7.1 receiver could claim it has a "640 Watt amplifier," which works out to about 20 vintage FTC wpc. It would probably go into instant clipping at "demanding" levels and toast vintage AR dome tweeters within a few minutes.

I just did a rough calc of my living room, and it works out to about 7900 cu ft. Don't even ask what our AC bill is like during the peak summer months in San Diego County, CA.

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