2ax tweeter swap

[Guest grassulo]

has anyone ever swapped the tweeters from the new style (black dome) ones to the ones that had the fried egg lookin ones? I have 2 pairs of 2ax's one older and one newer, they both have the older style flat dustcap woofers, I was an idiot and restuffed the cabinets of the newer style ones with polyester, their hopelessly boomy, and I also sealed the woofers in with silicone, so I'm not too hot on the idea of having to rip them out again and clean off all that nasty silicone junk. Can these tweeters be swapped to the older style speakers without changing the crossovers and still sound decent? I Havent finished refoaming the second pair of woofers yet, so I have yet to hear what the older tweeters sound like combined with the other drivers. I was told by a friend that since I listen to a lot of rock & techno, which usually has a lot of highs, that I'd be happier with the older style ones, and that the new style tweeters can be like fingernails on a chalkboard with certain songs, which I have noticed. So should I swap the tweeters or leave them as is? And has anyone ever used rubber gasket material to seal their woofers, so they'd be easy to remove to make adjustments to stuffing content? I was thinking of doing this to the newer pair, possibly trying stuffing them with pink panther fiberglass to try to recover the orignal sound, I threw the old stuff away like an idiot, since it was my first restoration, and some stuff you learn the hard way, you know?

-Garret

[Drewb]

Your boominess may not come from the Polyester. I stuffed my with loose (not packed) polyester and have no boominess. I assume you have the cloth surround woofers. Take them out and if you can see sunlight through the surround you have found your problem. The butyl rubber has dusted off and is not sealing the box properly. This can be rejuvinated.

Don't use Silicone, use "ductseal". You can get it at home depot in the electrical dept. This is the same stuff that AR used.

I had the same situation as you do with the tweeters. I was able to solve it by rebuilding the crossovers and using some Panasonic ribbon tweeters I had leftover from another project. Not authentic but great sounding.

I did find the coil value on the crossovers was different. This does not affect the tweeter. It moves the woofer/mid crossover point. What it means is that they will always sound slightly different. The old capacitor brick had increased in value and was leaky. Replacing it with new poly film caps has restored the sound to new.

I assume you have the new tweeters? Matching them will help since they are very different in sound. The newer fried egg has more output and may be why your friend considers it harsher. With a rebuilt crossover (and working pots) it would still be the tweeter of choice.

[tysontom]

>I was an idiot

>and restuffed the cabinets of the newer style ones with

>polyester, their hopelessly boomy, and I also sealed the

>woofers in with silicone, so I'm not too hot on the idea of

>having to rip them out again and clean off all that nasty

>silicone junk.swap the tweeters or leave them as is?

>And has anyone ever

>used rubber gasket material to seal their woofers, so they'd

>be easy to remove to make adjustments to stuffing content? I

>was thinking of doing this to the newer pair, possibly trying

>stuffing them with pink panther fiberglass to try to recover

>the orignal sound, I threw the old stuff away like an idiot,

>since it was my first restoration, and some stuff you learn

>the hard way, you know?

>

Garret,

Your message could not be more timely or important, because it points to the issue of going inside an acoustic-suspension enclosure and modifying or making changes, updates, etc. When you removed the fiberglass damping material in the enclosure, and changed it with something else, you changed the damping or "Q" of the speaker. You actually put too little material in the box, because you mentioned that it became "hopelessly boomy." The "Q" went up, and the damping went down, and a peak occurred in the response of the woofer, especially around the 52 Hz resonance frequency, thus the boomy sound.

There is a fairly critical amount of fiberglass damping material in each of the AR acoustic-suspension speakers, including the AR-2-series. This fiberglass, around 1.3 - 1.5 lbs. in the AR-2, damps out standing waves inside the cabinet and reduces the "Q" so that the rise at resonance is broadened. You could go down to your local Home Depot or Lowes and get some garden-variety fiberglass insulation material, and then tear it into relatively small pieces and put it in a plastic bag and weigh it until you get to about 1.3 lb to 1.5 lb. Take it out of the plastic bag, of course, and pack the fiberglass into the enclsure, take small pieces and stuff them between the wires in the crossover to keep everything from vibrating or rubbing together. Put the remainder of the fiberglass, evenly packed, in the enclosure all around, with some KemPac (similar to crepe paper) just under the woofer (unless your woofer has a plastic screen to keep out fiberglass). While you are at the hardware store you can get some Mortite -- a window putty that is in rope form -- and use that to seal the woofer. The woofer doesn't have to be hermetically sealed, but only acoustically sealed. Fix any *obvious* air leaks if possible. AR used to connect a sine-wave generator and amp to each speaker, apply 20 Hz and listen with a stethoscope around all the gaskets and such for air leaks. In the absence of this, if you gently push in the woofer from the center and quickly release, the cone should return fairly slowly. If it immediately pops back out, you have an air leak which also can affect damping. So long as the air leaks are minimal, the effect on performance is not great. Good luck!

--Tom Tyson

[Guest grassulo]

I just got one of the older (big brown tweeter) speakers back together and working, and noticed somthing VERY strange, the older larger brown tweeter seems to have more output than the newer little black one, from what I've read, this shouldn't be the case I'd imagine, perhaps one has an ailing crossover, wont matter to me much though, because the newer pair are going to be used for movies, hooked to my DVD player with a dynaco SCA-80 integrated amp driving them, I like the sound of the older ones for music better, so those are going to be the ones I have hooked up here, actually they'll be my computer's speakers, since my computer is hooked right into that nikko amp. Refoaming these 4 woofers has been fun, and I may end up with a pair of large advent's from my shop teacher, my dad will kill me, but oh well, he about had a heart attack when I brought FOUR 2ax's home!

-Garret

[Guest Pointwhere]

Did you ever get the boominess issue resolved? I have a smilar situation with a 303 speaker, I took out the stuffing, put it back in, and now the thing sounds like hell. Any guidance would be greatly appreciated, I hope whatever solved your problem may help me with mine.

[tysontom]

>Did you ever get the boominess issue resolved? I have a

>smilar situation with a 303 speaker, I took out the stuffing,

>put it back in, and now the thing sounds like hell....

Describe your situation in more detail. It's sort of like saying, "...my car has a strange vibration; it's a 2004 Chevrolet, can you help me?"

For example:

1. Describe what you consider to be "boominess."

2. What changes were made, if anything to the AR-303?

3. Do you know the amount of stuffing to be the same as original?

4. Has the crossover been modified or rewired in any way?

5. Have you determined (stethoscope) that there are air leaks?

6. Has the woofer been modified or changed in any way?

7. What amplifier is being used? Cables and length of cables.

8. When do you notice the "boominess," on music or test tones?

9. Are you able to measure this boominess you describe?

Any other information would be helpful.

--Tom Tyson

[Guest Pointwhere]

Point taken, I'll try to be more specific.

1) By "boomy," i mean that there are certain frequencies that play much lounder than others, even in an outdoor environment which should be free from room effects. Also, other frequencies seem to play softer. In addition, as the frequency aproaches one of the loud notes, the pitch becomes distorted because I can hear both the intended note and the resonant, loud note. Essentially, it sounds like a crappy bass-reflex speaker.

2) I bought these used, and the crossover had been replaced with a 303a crossover. SInce the drivers and cabinet are the same, I have been told that this should not make a difference, provided it was done correctly. This is the only change from the original design I am aware of.

3) Yes, I believe the stuffing is all there. I asked the original owner, and he claims he pulled it out to install the crossover and then put it all back in. I did the same just to see if it helped... The speaker is packed fairly tightly with some sort of poly type material. I can weigh it I suppose, if anyone knows the correct amount...

4) The crossover was modified as noted above by original owner.

5) I have not used a stethoscope to check for leaks, how does one do this? How large does a leak have to be to affect performance? Where do leaks generally occur, and what is the best way to repair them?

6) The woofer, to my knowledge, is original and has not been messed with. It has the number 2-11-001-1 printed on the back of it.

7) I have tried driving the speakers with 2 different receivers, a Marantz 6400 and a Sony thing from Circuit City. Using monster cable <6ft long, same result with both amps.

8) I originally noticed the boominess when listening to music, so I downloaded a test tone generator to find out more. There are *LARGE* response peaks in the vicinity of 150 and 50 Hz, although I cannot tell exact values from this software.

9) I have not been able to measure this effect except with my ears, what sort of equipment is appropriate?

Thanks for the help, and I really hope people find this subtopic to be related and useful, as opposed to pirating a thread, which was not my intent.

[Guest dogmeninreno]

Point taken, I'll try to be more specific.

1) By "boomy," i mean that there are certain frequencies that play much lounder than others, even in an outdoor environment which should be free from room effects. Also, other frequencies seem to play softer. In addition, as the frequency aproaches one of the loud notes, the pitch becomes distorted because I can hear both the intended note and the resonant, loud note. Essentially, it sounds like a crappy bass-reflex speaker.

I'd head for the xover. Do you have an audio generator or a function generator? Have you verified that ALL the drivers are the correct impedence? If air leaks are not a problem, This is the direction I would go. Check your xover points and maybe the problem will be found? Recommend to do this slowly and take notes!! One at a time! Dale

[Guest Pointwhere]

I don't think it's the crossovers, I should have specified... All the frequencies I was testing are in the 200-30 HZ range. All bass stuff, never heard any of it coming from the other drivers.

[tysontom]

>1) By "boomy," i mean that there are certain frequencies that

>play much lounder than others... Essentially, it sounds like a crappy bass-reflex speaker.

>

That last sentence makes it seem like bass distortion. The sounds you hear may be the fundamental frequency and overtones, and if this so it would appear to be a good case of harmonic distortion, but this is unlikely unless the woofers are defective or the amplifier is grevously underpowered. It could be the amp overdriving, but you used two different ones, and this seems questionable. What were the power ratings of those receivers? The loudness control and tone controls could certainly introduce boominess, although you did not mention those settings. It simply takes a *lot* of power to cause the AR-303 to distort unless there is a problem somewhere. The woofer(s) could also be defective, having been seriously overdriven by the previous owner. *Question: do you hear this "boominess" under relatively quiet or soft conditions, or only under high-power conditions, or under all conditions no matter the output level?

>2) I bought these used, and the crossover had been replaced

>with a 303a crossover. SInce the drivers and cabinet are the

>same, I have been told that this should not make a difference,

>provided it was done correctly. This is the only change from

>the original design I am aware of.

>

Are you absolutely certain these speakers have the AR-303a crossover and not one for the AR-302a? I don't know if the latter even fits, but I suspect that the woofer choke is different. This is obviously a wild guess.

>3) Yes, I believe the stuffing is all there. I asked the

>original owner, and he claims he pulled it out to install the

>crossover and then put it all back in. I did the same just to

>see if it helped... The speaker is packed fairly tightly with

>some sort of poly type material. I can weigh it I suppose, if

>anyone knows the correct amount...

>

I don't think I can find the weight of the synthetic stuffing used in the AR-303, but I will look through my files to see if I can find that information. Ken might remember, but it's an obscure detail.

>4) The crossover was modified as noted above by original

>owner.

>

>5) I have not used a stethoscope to check for leaks, how does

>one do this? How large does a leak have to be to affect

>performance? Where do leaks generally occur, and what is the

>best way to repair them?

The best way to test for air leaks in an acoustic-suspension speaker is to use a sine-wave generator (HP 200CD is a great one even as old as it is) set for 20 Hz., and drive the speaker with relatively low-wattage input (perhaps 5 watts rms, which is loud) and listen with a stethoscope all around the speaker rims for what used to be termed a "twittering" sound, whatever that is. Ironically, the effect of a poor seal is minor; if the leak is bad enough it would introduce enough of a resistive element to actually *increase* the damping and reduce the low-bass response a little. But you do not want excessive air leaks in any event, nor do you want the cabinet to be hermitically sealed.

>

>6) The woofer, to my knowledge, is original and has not been

>messed with. It has the number 2-11-001-1 printed on the back

>of it.

>

>7) I have tried driving the speakers with 2 different

>receivers, a Marantz 6400 and a Sony thing from Circuit City.

>Using monster cable <6ft long, same result with both amps.

>

>8) I originally noticed the boominess when listening to

>music, so I downloaded a test tone generator to find out more.

> There are *LARGE* response peaks in the vicinity of 150 and

>50 Hz, although I cannot tell exact values from this

>software.

>

>9) I have not been able to measure this effect except with my

>ears, what sort of equipment is appropriate?

>

If this effect is as clearly audible as you describe it, measuring would be helpful to compare to known curves of the speaker. There simply should not be large peaks at 50 and 150 Hz. According to the curves I have on the 303, there is a small, gradual rise in output of maybe 2.5 dB in the area of 50 Hz, but the effect is mainly a strong low-bass output, not boominess. The overall response from 500 Hz down to about 30 Hz is quite uniform, and would never suggest boominess. Somewhere in this thread are images done by someone on the bass output and impedance of the 303a. While these curves are perhaps not completely representative of the AR-303a, they nevertheless are close and give a good example of the output and impedance of the 303. The close-miked woofer response curve gives a clue to the smoothness, and one can see that the woofer has no abrupt output anomolies anywhere in the spectrum. The scaling or calibration did not seem exactly right on those curves, but they were fairly close to the curves I have.

We are no closer to identifying the problem than when you first mentioned it. Can you find someone else with a pair of AR-303s and compare the two sets?

--Tom Tyson

[johnieo]

>I don't think it's the crossovers, I should have specified...

> All the frequencies I was testing are in the 200-30 HZ range.

> All bass stuff, never heard any of it coming from the other

>drivers.

Is that a valid assumption? If there is one thing I learned in 45+ years of lab work was that assumpions caused me grief! We also learned that problems, which surfaced immediately after maintenance were usually be solved by asking: What was done during maintenance? In your case someone replaced the crossovers and in doing so removed/reinstalled stuffing, woofer seals, and crossover seals.

1. Are you *sure* the crossovers are correct? Tom Tyson mentioned that a similar but incorrect crossover could have been inadvertently installed. Have you compared the components/circuit in your crossover with the crossover circuit diagram posted on the Arsenal.net website? Are you sure the crossover does not have a broken solder joint, a cold solder joint, or an un-insulated wire touching something it shouldn't?

2. Did the last person--or perhaps the person before that--replace all the fiberfill? I believe it should weight about 2.2 pounds, but don't assume that! When you stated that you took half the filling from one speaker and stuffed it in the other, it raised an eyebrow or two, as they should be quite tighly packed--not easy to add half more.

3. Do the woofer and crossover seals leak? As Tom suggested try depressing and releasing the cone or the sine wave test.

If those are all OK, one other difference might be your amplifers. Sometimes this can be frustrating.

cheers

[Guest Pointwhere]

In answer to the question above, I hear the boominess/distortion regardless of volume level, but it becomes more pronounced as volume is turned up. As far as receiver wattages, the Marantz is 100wpc with separate amps for each channel. I don't know any specs about the sony, I'm guessing 50-60wpc.

Is there any chance that the problem could be standing waves produced inside the cabinet and forcing some unnatural movement in the woofer cone? Just an idea. Thanks everyone for your continuing support as I go nuts!