28 replies to this topic

[JKent]

Perhaps Carl is correct and the administrators should move this discussion to the alternate section where people are open to modification of existing designs. It's not my mission to offend anyone.

Like maybe the Kitchen?
Really--the rhetoric IS getting to be a bit strident.
XP: You need to realize that this forum is dedicated to classic AR speakers and many here view the 3a as the sine qua non of speakers. So when you trash it--both figuratively and, if you go ahead as planned, literally--people get excited.
If the Quad ESL is YOUR idea of the ideal speaker (a fine speaker I'm sure), then maybe the "classic New England" acoustic suspension box is not for you. You may be better off selling the 3a's "unmolested" and using the money to buy something more to your liking.
I recently had the pleasure of auditioning (briefly) the Carver Amazing speakers. Full-range ribbons with 4 big cone woofers for frequencies below (I think) 100 Hz. There are lots of planar and electrostatic speakers that are highly regarded, and they are all quite different from "boxes" like those discussed in these pages.
If you DO like some things about the ARs but not the tweeters, mids, or the "frames" that cause diffraction problems, review michiganpat's very sensible recommendations in post #5. I can tell you I just completed an AR91 restoration and they are fine speakers indeed. And they correct the things you dislike. However, I really like the 3a so maybe my opinion is too slanted. Gene also made a very sensible recommendation: The 3a is designed so you can power just the woofer. Remove the jumper then add a pair of mini monitors that you like.
And you're right: No one has addressed your initial question: How do Carl's speakers sound? We're still waiting for answers to that.
But remember your audience here. Let's put it this way: If I were in a position to collect cars, I'd love to have a '58 Corvette. Now you could argue that it could be "improved" by dropping in a new engine, 6-speed trans, ABS disc brakes, and so on. But it would no longer be a classic car.

Kent

[michiganpat]

Let's talk about the subject at hand; how Carl's mod actually performs/sounds. All else is off-topic, though I also welcome discussion of alternatives to Carl's mod. The goal is to have the ultimate 3-way, sealed box system with a 12" woofer. It really doesn't matter to me how I get there. I'm not the least bit interested in keeping my AR-3a's original for collectible value.

if you're looking for that elusive "imaging", at the very least, you'll need to more or less mirror image the mids/tweets. that why I'd suggest maybe new cabs, because it's going to be a lot of pain to re-do the baffles....other than that, without ever hearing them, I'd guess you're going to have a hard time improving on Carl's supermod without a lot of time, measuring equipment, and knowledge of crossover design and simulation software (PCD)...

Carl, have you ever measured the in-box Q of the 3/3a? would it benefit from a slightly larger cabinet? just curious

with the crazy-stupid prices 3's/3a's go for on fleabay, you might be money ahead selling your "originals" (especially if you have the original tweets to go with them), and pick up a pair of AR 12" woofers and build new cabs, or some AR 1's that the altec driver has been removed from, or some 1W's (woofer only, the rest of the baffle is free to cut as you like)

[Carlspeak]

if you're looking for that elusive "imaging", at the very least, you'll need to more or less mirror image the mids/tweets. that why I'd suggest maybe new cabs, because it's going to be a lot of pain to re-do the baffles....other than that, without ever hearing them, I'd guess you're going to have a hard time improving on Carl's supermod without a lot of time, measuring equipment, and knowledge of crossover design and simulation software (PCD)...

Carl, have you ever measured the in-box Q of the 3/3a? would it benefit from a slightly larger cabinet? just curious

with the crazy-stupid prices 3's/3a's go for on fleabay, you might be money ahead selling your "originals" (especially if you have the original tweets to go with them), and pick up a pair of AR 12" woofers and build new cabs, or some AR 1's that the altec driver has been removed from, or some 1W's (woofer only, the rest of the baffle is free to cut as you like)

Mirror imaging won't help acoustic imaging. Been there, done that with a pair of AR-1W's.

In-box Q will vary with stuffing type and amount. Typically, I get in the range of 0.6 to 0.9 when I measure it. Don't know if a larger box will help. OTOH, IIRC, the whole objective of AS design was smaller boxes. That's what brought E.V. fame and fortune.

I've just finished a new personal 2-way vented mini-monitor project involving some high end drivers in 1/2 cu. ft. box that image great and would look great sitting atop a pair of handsomely refinished 3a cabs with woofers. As they stand now, the 2-ways get down well below 100 hz. and might be too much bass when coupled with the 3a woofers without some minor crossover changes to raise F3 on the MM's. It's doable, but not without some tweaking. In fact, I might try them out with the 3a's I have. I'll just turn off the tweets and mids and see and listen to what happens. Right now, they're sitting atop some KLH-5's awaiting restoration.

[michiganpat]

Mirror imaging won't help acoustic imaging. Been there, done that with a pair of AR-1W's.

In-box Q will vary with stuffing type and amount. Typically, I get in the range of 0.6 to 0.9 when I measure it. Don't know if a larger box will help. OTOH, IIRC, the whole objective of AS design was smaller boxes. That's what brought E.V. fame and fortune.

interesting....I always assumed having vertically aligned and mirrored drivers (or at the very least, mirror imaged drivers) for the midrange on up was necessary to get any sort of "imaging", especially nearfield. do they image better if placed on their side, so the mid & tweet are more closely aligned vertically? again, just curious....

just wondering about the Q, as I've heard people who've measured Large Advents even after heavily stuffed only getting them down to ~.8 Q, and complain about the 1.5 decibel bass hump in them....my thinking with the bigger box was also to give more height to allow for the mid/tweet to be aligned on the same vertical axis, to improve imaging, ala the 303/303a....

[Carlspeak]

interesting....I always assumed having vertically aligned and mirrored drivers (or at the very least, mirror imaged drivers) for the midrange on up was necessary to get any sort of "imaging", especially nearfield. do they image better if placed on their side, so the mid & tweet are more closely aligned vertically? again, just curious....

just wondering about the Q, as I've heard people who've measured Large Advents even after heavily stuffed only getting them down to ~.8 Q, and complain about the 1.5 decibel bass hump in them....my thinking with the bigger box was also to give more height to allow for the mid/tweet to be aligned on the same vertical axis, to improve imaging, ala the 303/303a....

Over 80 posts at this thread on imaging http://www.diyaudio....od-imaging.html and no mention made of driver placement on the BB as being a key contributor. Some heavy hitters posted here (much more so than I, for sure). Geddes, Olson, Bateman, etc...

BTW, thanks Gene for moving the thread.

[Carlspeak]

I'm glad you at least plan to move it. I'm also hoping some Super-Mod owners spot this thread and contribute their un-solicited (at least from me) comments on the sound. I wasn't planning to add mine personally; simply because they would obviously be viewed as biased. All I'll say is the intent of the SM development was to preserve the original laid back sound of the 3a's but improve on the overall clarity and imaging thru the use of high quality, modern mids and tweeters.
You alude to a mod of the SM to "bring it's tonal balance in line with that of the original". IMHO, I'm not sure that's necessary since I've heard no feedback that the 'tonal balance' was changed with the SM. Let's not speculate on what may or may not have changed. Let the owners of the SM make that call.

I took it upon myself to ask my last SM customer what he thought of the sound now and as compared to his memory of the original 3a sound. Here was his response FWIW:

"Hi Carl,

One might say the sound is more forward, but it is not bright. It is good tone with a clear, well resolved modern sound. I should think with separate adjustments of the mid and tweeter one could achieve a good approximation of the originals. Particularly since the AR-3 sound was defined by the acoustic suspension woofer, and that is still present. I thoroughly enjoy them modded, yet they will be forever AR.

Regards,

Joel"

[bitbandit]

Someone suggested that a later model of speaker from the AR58 era might help.

I have 2ax, 3a, 3a improved, 58LS and 98LS. I prefer the sound of the 2ax/3a midrange, the 58LS and 98LS are a good deal brighter and more modern sounding but to my ears a little harsher, even with the crossover mods to tone things down a bit. They are all great speakers, all sound slightly different and in the end it comes down to what you prefer as an individual.

My take is that the deepest gut shaking bass comes from the 3a improved, but the most accurate bass comes from the 98LS (which is a 4 way and uses an 8" lower mid, so not a fair comparison really). Most accurate mid range is in the 2ax, and the clearest tweeter is in the 58LS/98LS.

Of course some of the drivers are the same across models, the crossovers make a big difference and even within models variance with crossover parts used occurs. In my experience, the room, furnishings or location within the room can sometimes make a bigger difference than switching models.

I could try and make a new hybrid of all the best bits, but I love the sound of each pair as they are, and I would not want to lose any one of them in the hope of making something that may sound better.

Just my humble opinion.

[dynaco_dan]

Someone suggested that a later model of speaker from the AR58 era might help.



I prefer the sound of the 2ax/3a midrange,



the 58LS and 98LS are a good deal brighter and more modern sounding but to my ears a little harsher, even with the crossover mods to tone things down a bit. They are all great speakers, all sound slightly different and in the end it comes down to what you prefer as an individual.

Hi there

A very interesting comment and comparison of the midrange drivers sound.

The 3A of course uses a different 1 1/2 dome driver.

The AR-2AX's used the cone tweeter with the fiberglass and mesh cover, at least during later production.

I have seen on a few occassions where there was no fiberglass under the screen, very likely early production.

Actually the same driver was used for the AR-4, early AR-1X, and early AR-2X's mid/tweeter driver.

Obviously AR researched their modifications to the OEM driver and what a success it became.

[Gerry S]

I've owned AR3a's, Allison One, AR10Pi and many others. ALL have their "pro's" and "con's" depending on what one is looking to achieve. In other words, no one speaker can be all things to all people. As others have said, room properties, speaker placement and source material can make any speaker brand/ model sound "better" than another just by manipulating those three variables. But "better" compaired to what? And how would you quantify this ?

I feel that making ANY changes that deviate from the designers's "original intent" in a significant way is NOT a "restoration" but a "re-design". In the real world, there are these things called "manufacturing tolerances". There are also "iterations" and "revisions" in the manufacturing process that attempt to keep each product rolling off the assembly line as "identical" as that "magic reference". As a former designer that began my career in the late 80's , it was tough to that then ! I can only imagine how difficult it was to do this when the "classics" were being developed and manufactured in the 60's.

So, whenever you make a "mod" (like substituting a "better" driver or "better" cap), what you're REALLY doing is changing how the driver "interacts" with the crossover, which determines the overall radiation pattern (directivity) and "frequency response" of the "first arrival" sound. It will also affect the impedance of the system, which may or may not change the way it "couples" to the amplifier used. The AR3a is notorious for it's very low and reactive impedance ; only the "better" amplifiers (those with a hefty power supply) of that era could do it justice.

As to "imaging" (a quality I personally desire), "mirror imaging" by itself won't get the job done unless tolerances are held "tight" AND the inheritant design is CAPABABLE of "imaging". I believe there is a necessary "trade-off" between a "tight focus" and "spaciousness". You can have a Bose 901 (which is inherently "mirror imaged") and manufactured to the tightest tolerances possible, and it STILL won't "focus" like a speaker designed with "tight imaging" as it's primary design objective.

Gerry S