AR-2ax Modifications

[Guest kevemaher]

010708_AR_2ax_Woofer_Measurements.doc

Hi,

A few months ago, I posted some woofer measurements. Pete B. was kind enough to point out some problems with these measurements. After a few months of major changes, I am reporting more measurements. I have a pair of the "new" AR-2ax speakers with badges that read "AR-2xa". I decided that I would replace the mid and tweeter with some modern drivers and tri-amp the system. I settled on a 4.5" dia. SEAS mid and a SEAS tweeter. The new mid fits exactly into the tweeter hole. The new tweeter does not fit the mid hole, so I bonded and sealed the tweeter in place with silicone adhesive. This is flexible, airtight, and is easy to remove if needed. There's a photo attached.

The new mid required its own air chamber, so I cut a piece of 4" PVC pipe to the length of the inside of the cabinet (about 9"). This is almost exactly the volume recommended by SEAS (0.065 cu. ft.) and does not appreciably change the internal volume (from 1.4 to 1.33 cu. ft.). This was carefully positioned below the mid and sealed with caulk on bottom and top and stuffed tightly with Fiberglas. I added an impedance flattening (Zobel) circuit to the mid and a DC protection capacitor to both drivers. The entire AR electronics board was removed and replaced with 3 binding post pairs (holes appropriately sealed). I added a Zobel to the woofer, new sealant to the rim and stuffed the box with 2.5 lbs of Acoustastuff.

I use an active crossover and 3 power amplifiers. The crossover allows for user-selectable crossover frequencies and level adjustment for all drivers. I settled on 250 Hz and 2KHz as the crossover frequencies and a slight bass boost.

Measurements... The attached word file has three graphs.

The first graph shows the woofer impedance vs. frequency for the bare woofer and then for both woofers sealed in the cabinets. The Fs and Fc values are very close to those reported by Pete B. This indicates that the Acoustastuff is an effective replacement for the scrarchy Fiberglas. The Fc and Zc values provide a Qtc = 0.79 for "C" and 0.89 for "D", indicating a reasonably smooth low frequency roll-off. The Zobel is very effective in flattening the high frequency impedance rise from the woofer self-inductance. Values are R = 8 ohms and C = 24 microfarads. This may not really be necessary with the 4th order LR crossover, but may be effective with the stock crossover. I checked the predicted low frequency roll-off using box software available on the ESP website (Elliott Sound Products). It doesn't match the measured performance at all.

The second graph shows SPL as a function of frequency. This measurement was done with a calibrated SPL meter. Fixed frequency Sine Wave test tones and Pink Noise were generated with software and saved to a CD. These were then played back through the system. "C" weighting was used, so the measurements are accurate from 30 Hz to 16 KHz. I am troubled by the sharp dip at 70 Hz and the broad deep trough between 200 and 400 Hz. I tried many different speaker placements in the room and even outside away from obstructions, but these features remained. Previously, I had carefully re-foamed both woofers with surrounds available from a reputable AR parts supplier on eBay. Could these dips be from the surrounds? I am not pleased with this performance and am currently looking for woofer replacements. Does anyone have a suggestion for a reasonable replacement?

The third graph is a Frequency Response graph. I used LabView software to capture wave files generated using an omnidirectional microphone and an external soundcard and then performed an FFT. This is a digital analog to a Spectrum Analyzer. I am limited by computer memory to a record length of about a minute. Pink noise was fed into all drivers. The dip in the woofer output was corrected somewhat by lowering the woofer/mid crossover frequency. I am encouraged that I can obtain a reasonably flat FR curve with a better performing woofer.

Overall, this system sounds excellent despite its flaws. I heartily recommend tri-amping as it provides enormous control and flexibility. However, the speakers have become far different from the original AR design, especially if I replace the woofers. Nonetheless, this has been an enormous learning experience.

Comment, criticism, and encouragement are always welcome.

Kevin

[Carlspeak]

Nice effort Kevin.

Have you looked at playing with the mid's polarity?

The upper end of your SPL curve is quite low. Another polarity issue perhaps?

Hope the restorers who visit here aren't offended by your efforts.

It took me 3 months to get my 3a Super-Mod SPL response reasonably flat.

[Guest kevemaher]

Carlspeak,

Thanks for the kind words. What you've done for the AR-3a encouraged me to see what I could do for the AR-2ax.

I settled on the active xover after costing out the components for a passive xover. Active really is not much more expensive, especially if you want to vary the xover frequencies. It also provides driver to driver output balancing at the turn of a knob.

The 4th order LR active xover does not call for polarity reversal. I added some bass boost because I like the sound that way.

I am perplexed by the roughness of the woofer's FR and hole at 200-400 Hz and wondering if I can do better. Suggestions anyone?

I also have and regularly listen to and enjoy my stock Dynaco A35, Large Advent, and "Old" version AR-2ax speakers. This effort is purely a learning experience for me. Perhaps I should have posted in the Mods Forum.

By the way, I am using an Apt preamp and power amps (ca. 1980).

Kevin

[Carlspeak]

Carlspeak,

Thanks for the kind words. What you've done for the AR-3a encouraged me to see what I could do for the AR-2ax.

I settled on the active xover after costing out the components for a passive xover. Active really is not much more expensive, especially if you want to vary the xover frequencies. It also provides driver to driver output balancing at the turn of a knob.

The 4th order LR active xover does not call for polarity reversal. I added some bass boost because I like the sound that way.

I am perplexed by the roughness of the woofer's FR and hole at 200-400 Hz and wondering if I can do better. Suggestions anyone?

I also have and regularly listen to and enjoy my stock Dynaco A35, Large Advent, and "Old" version AR-2ax speakers. This effort is purely a learning experience for me. Perhaps I should have posted in the Mods Forum.

By the way, I am using an Apt preamp and power amps (ca. 1980).

Kevin

Thanks Kevin.

Your approach using active xovers was certainly a novel one. Did you look at the polarity issue?

Your comment regarding the location of your original post is spot on. Suggest future posts on your project (if any) be done in the mods and tweaks area as you mentioned. Restorers tend to want only restoration & vintage related posts to reside in the speaker named discussion areas.

[Pete B]

010708_AR_2ax_Woofer_Measurements.doc

Hi,

snip ...

Measurements... The attached word file has three graphs.

The second graph shows SPL as a function of frequency. This measurement was done with a calibrated SPL meter. Fixed frequency Sine Wave test tones and Pink Noise were generated with software and saved to a CD. These were then played back through the system. "C" weighting was used, so the measurements are accurate from 30 Hz to 16 KHz. I am troubled by the sharp dip at 70 Hz and the broad deep trough between 200 and 400 Hz. I tried many different speaker placements in the room and even outside away from obstructions, but these features remained. Previously, I had carefully re-foamed both woofers with surrounds available from a reputable AR parts supplier on eBay. Could these dips be from the surrounds? I am not pleased with this performance and am currently looking for woofer replacements. Does anyone have a suggestion for a reasonable replacement?

The third graph is a Frequency Response graph. I used LabView software to capture wave files generated using an omnidirectional microphone and an external soundcard and then performed an FFT. This is a digital analog to a Spectrum Analyzer. I am limited by computer memory to a record length of about a minute. Pink noise was fed into all drivers. The dip in the woofer output was corrected somewhat by lowering the woofer/mid crossover frequency. I am encouraged that I can obtain a reasonably flat FR curve with a better performing woofer.

Overall, this system sounds excellent despite its flaws. I heartily recommend tri-amping as it provides enormous control and flexibility. However, the speakers have become far different from the original AR design, especially if I replace the woofers. Nonetheless, this has been an enormous learning experience.

Comment, criticism, and encouragement are always welcome.

Kevin

Hi Kevin,

I'd say that you are seeing room effects to answer your woofer's response issues, or

some artifact in your measurement method. A room is a cavity resonator with many

modes depending on the dimensions of the room, it is very complex. It is impossible

to do bass measurements in room, other than near field, which are only good up to

about 200 to 300 Hz for a 10" woofer.

http://www.linkwitzlab.com/rooms.htm

Did you do a ground plane measurement outdoors? Or just face the system pointing

upward? The path delay from the baffle to the ground will cause response errors,

you have to bury it in the ground to eliminate these effects.

You might want to look for a copy of Joe D'Appolito's book "Testing Loudspeakers"

[Pete B]

010708_AR_2ax_Woofer_Measurements.doc

Hi,

A few months ago, I posted some woofer measurements. Pete B. was kind enough to point out some problems with these measurements. After a few months of major changes, I am reporting more measurements. I have a pair of the "new" AR-2ax speakers with badges that read "AR-2xa". I decided that I would replace the mid and tweeter with some modern drivers and tri-amp the system. I settled on a 4.5" dia. SEAS mid and a SEAS tweeter. The new mid fits exactly into the tweeter hole. The new tweeter does not fit the mid hole, so I bonded and sealed the tweeter in place with silicone adhesive. This is flexible, airtight, and is easy to remove if needed. There's a photo attached.

The new mid required its own air chamber, so I cut a piece of 4" PVC pipe to the length of the inside of the cabinet (about 9"). This is almost exactly the volume recommended by SEAS (0.065 cu. ft.) and does not appreciably change the internal volume (from 1.4 to 1.33 cu. ft.). This was carefully positioned below the mid and sealed with caulk on bottom and top and stuffed tightly with Fiberglas. I added an impedance flattening (Zobel) circuit to the mid and a DC protection capacitor to both drivers. The entire AR electronics board was removed and replaced with 3 binding post pairs (holes appropriately sealed). I added a Zobel to the woofer, new sealant to the rim and stuffed the box with 2.5 lbs of Acoustastuff.

I use an active crossover and 3 power amplifiers. The crossover allows for user-selectable crossover frequencies and level adjustment for all drivers. I settled on 250 Hz and 2KHz as the crossover frequencies and a slight bass boost.

Measurements... The attached word file has three graphs.

The first graph shows the woofer impedance vs. frequency for the bare woofer and then for both woofers sealed in the cabinets. The Fs and Fc values are very close to those reported by Pete B. This indicates that the Acoustastuff is an effective replacement for the scrarchy Fiberglas. The Fc and Zc values provide a Qtc = 0.79 for "C" and 0.89 for "D", indicating a reasonably smooth low frequency roll-off. The Zobel is very effective in flattening the high frequency impedance rise from the woofer self-inductance. Values are R = 8 ohms and C = 24 microfarads. This may not really be necessary with the 4th order LR crossover, but may be effective with the stock crossover. I checked the predicted low frequency roll-off using box software available on the ESP website (Elliott Sound Products). It doesn't match the measured performance at all.

The second graph shows SPL as a function of frequency. This measurement was done with a calibrated SPL meter. Fixed frequency Sine Wave test tones and Pink Noise were generated with software and saved to a CD. These were then played back through the system. "C" weighting was used, so the measurements are accurate from 30 Hz to 16 KHz. I am troubled by the sharp dip at 70 Hz and the broad deep trough between 200 and 400 Hz. I tried many different speaker placements in the room and even outside away from obstructions, but these features remained. Previously, I had carefully re-foamed both woofers with surrounds available from a reputable AR parts supplier on eBay. Could these dips be from the surrounds? I am not pleased with this performance and am currently looking for woofer replacements. Does anyone have a suggestion for a reasonable replacement?

The third graph is a Frequency Response graph. I used LabView software to capture wave files generated using an omnidirectional microphone and an external soundcard and then performed an FFT. This is a digital analog to a Spectrum Analyzer. I am limited by computer memory to a record length of about a minute. Pink noise was fed into all drivers. The dip in the woofer output was corrected somewhat by lowering the woofer/mid crossover frequency. I am encouraged that I can obtain a reasonably flat FR curve with a better performing woofer.

Overall, this system sounds excellent despite its flaws. I heartily recommend tri-amping as it provides enormous control and flexibility. However, the speakers have become far different from the original AR design, especially if I replace the woofers. Nonetheless, this has been an enormous learning experience.

Comment, criticism, and encouragement are always welcome.

Kevin

I'm not sure exactly which SEAS mid you are using but if it is a true short throw midrange

then a 250 Hz crossover point is a bit low, probably workable but 350 to 500 might be

better.

I seem to recall that you were using a LR4 active crossover but keep in mind that you

have to account for the acoustical responses of the drivers. A LR4 is actually the cascade

of two B2 (second order Butterworth) sections, and it is best to use the 2nd order rolloff

of the mid and tweeter low end as one of these sections. They are usually not at the

correct frequency and a Linkwitz Transform can be used to "re-align" them, doing so

can provide a near perfect LR4 cascaded response: http://www.linkwitzlab.com/filters.htm#9

also: http://www.linkwitzlab.com/x-sb80-3wy.htm

One way to check if you are even close to the correct transfer functions is to reverse the

polarity of the midrange. Since the LR4 is an inphase design, it should now be exactly out

of phase and you should see deep response nulls at the crossover points.

Rather complex for a small speaker with serious diffraction issues, but I understand that

you are just experimenting and learning which is fine. Enjoy!

[Guest kevemaher]

Pete,

Thanks for your thoughtful responses. I also believe that the variation below 100Hz is probably room effects. I have measured outside before and gotten similar results, but I should re-measure once again when it stops raining. I am more concerned with the big dip in the 200-400 Hz region. i moved the active LR4 xover F down to help flatten the FR. I have measured the mid separately w/o the xover and you are right, 250 Hz is a little low. I installed a different 10" woofer in the same cabinet and although the very low F FR bumps are still there the big -10dB hole 200-400 Hz is gone and is now very flat, so I can move the xover F up some.

On another point, it seems that the new driver has a lower Qs then stated in the literature. I have measured Fs and Fc an they are exactly as predicted from the driver literature and the Vas and Vb, but the Qc is lower than I'd like (0.5). Can I get it up to about 0.6 by adding more stuffing? Or less stuffing? Or by making the woofer volume smaller?

I agree that all this efort seems ridiculous in a 40 year old box. I'm not good at woodworking and don't want to spend a lot of $$. Are there places where I can get a box better suited for what I'm doing?

Kevin

[Pete B]

Pete,

Thanks for your thoughtful responses. I also believe that the variation below 100Hz is probably room effects. I have measured outside before and gotten similar results, but I should re-measure once again when it stops raining. I am more concerned with the big dip in the 200-400 Hz region. i moved the active LR4 xover F down to help flatten the FR. I have measured the mid separately w/o the xover and you are right, 250 Hz is a little low. I installed a different 10" woofer in the same cabinet and although the very low F FR bumps are still there the big -10dB hole 200-400 Hz is gone and is now very flat, so I can move the xover F up some.

On another point, it seems that the new driver has a lower Qs then stated in the literature. I have measured Fs and Fc an they are exactly as predicted from the driver literature and the Vas and Vb, but the Qc is lower than I'd like (0.5). Can I get it up to about 0.6 by adding more stuffing? Or less stuffing? Or by making the woofer volume smaller?

I agree that all this efort seems ridiculous in a 40 year old box. I'm not good at woodworking and don't want to spend a lot of $$. Are there places where I can get a box better suited for what I'm doing?

Kevin

Hi Kevin,

I wouldn't expect foam replacement to cause a problem in the 200 to 400 Hz range, the edge can provide a termination for standing waves in the cone and thus impact the breakup modes, however I would not expect it in that range. It is the frequency where boundary reflections are likely to cause cancellation.

Do you want to tell us what driver you substituted?

You would raise Qtc by pushing the damping material away from the back of the driver, by removing some, or by adding some series resistance.

No problem with the old box, it was just a comment. PE and Madisound both have prefab boxes, but not very large, you'd probably have to put the mid and tweeter box on top of the AR box.

[Guest kevemaher]

Pete,

Thanks for your response. Hmmmm...I'm not sure what's going on with the AR 10" woofer.

The replacement drivers I've picked are : SEAS 27TFFC tweeter, Seas H1152 Mid, and Dayton RSS265HF-4 woofer.

I made some careful TS parameter measurements of the Dayton woofer this weekend and was very disappointed. The Qts was much lower than their spec sheet (0.32 meas. vs 0.4 spec). In the cabinet, the Qtc was 0.5 vs the calculated value of 0.62). The -3dB was at 50Hz not the calculated 40Hz. So I'm shipping it back to PE.

The new replacement is the one that I wanted in the first place but was scared away by the price; ScanSpeak 25W/8565-00. This has a very high Qts and will probably have a bump before LF roll-off, but should get me down to 40Hz -3dB in the AR-2ax box. I will probably need to brace the box between the mid and woofer as the baffle board vibrates strongly at low freq and high levels and causes the mid cone to move with no drive applied. I've re-caulked around the mid enclosure, but it still vibrates. I'll add some 3/4" MDF braces inside.

Thanks for the tip on the stuffing. The Madisound folks also think that I may have overstuffed.

I've also thought about buying a box just for the woofer. I can then stand the AR-2ax box sideways on top and a little forward to achieve both vertical and time alignment. But this may be getting a little too wierd. I just may get up the courage to build my own box(es).

Kevin

PS: Pete, maybe we should continue this discussion on the Tweaks and Mods Forum. What we're discussing now is very valuable to me, but is far, far away from a classic restoration.

KM

[Pete B]

Pete,

Thanks for your response. Hmmmm...I'm not sure what's going on with the AR 10" woofer.

The replacement drivers I've picked are : SEAS 27TFFC tweeter, Seas H1152 Mid, and Dayton RSS265HF-4 woofer.

I made some careful TS parameter measurements of the Dayton woofer this weekend and was very disappointed. The Qts was much lower than their spec sheet (0.32 meas. vs 0.4 spec). In the cabinet, the Qtc was 0.5 vs the calculated value of 0.62). The -3dB was at 50Hz not the calculated 40Hz. So I'm shipping it back to PE.

The new replacement is the one that I wanted in the first place but was scared away by the price; ScanSpeak 25W/8565-00. This has a very high Qts and will probably have a bump before LF roll-off, but should get me down to 40Hz -3dB in the AR-2ax box. I will probably need to brace the box between the mid and woofer as the baffle board vibrates strongly at low freq and high levels and causes the mid cone to move with no drive applied. I've re-caulked around the mid enclosure, but it still vibrates. I'll add some 3/4" MDF braces inside.

Thanks for the tip on the stuffing. The Madisound folks also think that I may have overstuffed.

I've also thought about buying a box just for the woofer. I can then stand the AR-2ax box sideways on top and a little forward to achieve both vertical and time alignment. But this may be getting a little too wierd. I just may get up the courage to build my own box(es).

Kevin

PS: Pete, maybe we should continue this discussion on the Tweaks and Mods Forum. What we're discussing now is very valuable to me, but is far, far away from a classic restoration.

KM

Did that woofer bolt right in?

How did you measure the parameters?

What did you measure as the inbox Fc?

Reducing the box volume will raise Fc and Qtc.

I'd reduce the volume until you get an Fc of 40 to 45 Hz,

put most of the stuffing at the mid/tweeter end.

Leave about 4 to 6" clear behind the woofer, you

could line the back wall behind the woofer.

As far as boxes go, you want a low diffraction box for the

mid and tweeter, the LF is not critical so you could use

the 2ax. The old egg used in the Waveform:

http://ldsg.snippets.org/graphics/mach_17.jpg

We can move but I'd rather not fragment the discussion, can they move

the whole thing?

[Guest kevemaher]

Pete,

I'm fine with staying right here. I was just thinking that this discussion might be offending some people.

I had to slightly enlarge the cutout with a razor blade and then drill new mounting holes for the 6 each 8-32 bolts and t-nuts to get the Dayton woofer in. The ScanSpeak woofer will also fit in with yet another bolt circle. I re-use the AR putty (That stuff is truly amazing! Just pick the wood chips out, knead it all back together, and then roll out new putty lines.).

I measured the Fc, Qts, and Zc using a technique described in the ESP (Elliott Sound Products) website. Link is: http://sound.westhost.com/tsp.htm. I used the same method both outside and inside the box.

He has a spreadsheet you can download that does all the calcs for you. I generate fixed frequency sinewave audio .wav files and save them to a CD. I then play the sine waves back through the system just like tracks on a CD (but only to the woofer under test). I make my measurements at each frequency with two DVMs and record directly into my own prepared spreadsheet.

So I could buy a small box from PE or Madisound and jigsaw holes out for the mid and tw. I'd still need an inner chamber for the mid. To get the tweeter at near ear level, I'd probably have to rotate the AR box 90 deg. Or I could hacksaw it in half and re-seal. Box volume might be too small for the ScanSpeak.

Kevin

[Guest kevemaher]

Pete,

In-box Fc is 37.5 Hz for the Dayton woofer. Published Fs is 22.7 Hz.

Kevin

[Pete B]

Pete,

I'm fine with staying right here. I was just thinking that this discussion might be offending some people.

I had to slightly enlarge the cutout with a razor blade and then drill new mounting holes for the 6 each 8-32 bolts and t-nuts to get the Dayton woofer in. The ScanSpeak woofer will also fit in with yet another bolt circle. I re-use the AR putty (That stuff is truly amazing! Just pick the wood chips out, knead it all back together, and then roll out new putty lines.).

I measured the Fc, Qts, and Zc using a technique described in the ESP (Elliott Sound Products) website. Link is: http://sound.westhost.com/tsp.htm. I used the same method both outside and inside the box.

He has a spreadsheet you can download that does all the calcs for you. I generate fixed frequency sinewave audio .wav files and save them to a CD. I then play the sine waves back through the system just like tracks on a CD (but only to the woofer under test). I make my measurements at each frequency with two DVMs and record directly into my own prepared spreadsheet.

So I could buy a small box from PE or Madisound and jigsaw holes out for the mid and tw. I'd still need an inner chamber for the mid. To get the tweeter at near ear level, I'd probably have to rotate the AR box 90 deg. Or I could hacksaw it in half and re-seal. Box volume might be too small for the ScanSpeak.

Kevin

I've always felt that it is best to learn about driver measurements by doing it manually,

there is also Speaker Workshop which is free, but there is a learning curve and it is best

to use the suggested jig. I use PC based LAUD which works well.

There are software based function generators for the PC on the web for free, Marchand

has fg_lite.exe here, bottom of the page:

http://www.marchandelec.com/fg.html

I'd just turn the 2-ax box upside down and put another on top. I've not looked at that

Scan in some time, but I believe that you're right about the volume. Here is a picture

of the Aerial 10T: http://ldsg.snippets.org/graphics/b10trose.jpg

For that price, I'd use the Aura 10", have to check some simulations and mounting first.

OK nevermind, just looked closer, the cone mass is too high, and efficiency too low, the

12" version is a much better driver:

http://www.madisound.com/catalog/product_i...b09e5fc06fbcafb

Might want to take a look at this or the DVC version if you want 4 ohm, don't know if

it will mount easily:

http://www.partsexpress.com/pe/showdetl.cf...tnumber=296-430

I'd reduce the volume of your enclosure (put blocks of wood or styrofoam inside) as a

last resort for the Dayton woofer that you currently have, until

you get Fc up around 40 or 45 Hz, the Q will go up and the response should be better.

That is an impressive woofer, however it probably has too much magnet (100 oz) for

this application. You could add 1 ohm in series to throw away a bit of the motor strength

which will also raise the Q.

You've chosen some excellent drivers - Enjoy your project!

[RoyC]

Lets see, we've replaced the AR-2ax tweeter, the mid, the woofer, the crossover....probably the cabinet. I believe there MAY still be AR-2ax badges in the mix. I doubt this project even qualifies as a "mod or a tweak" !

Roy

[Pete B]

Lets see, we've replaced the AR-2ax tweeter, the mid, the woofer, the crossover....probably the cabinet. I believe there MAY still be AR-2ax badges in the mix. I doubt this project even qualifies as a "mod or a tweak" !

Roy

He said he didn't want to do woodworking so yes it is a new speaker. I personally

have more interest in new designs than some of the lesser classics. I could say more

but I'll refrain given the forum. Let me just say that I've not bothered to restore my

AR-2ax's and I too will probably replace the drivers some day since I don't like any of

them and mine are not in good shape as far as the finish goes.

[RoyC]

He said he didn't want to do woodworking so yes it is a new speaker. I personally

have more interest in new designs than some of the lesser classics. I could say more

but I'll refrain given the forum. Let me just say that I've not bothered to restore my

AR-2ax's and I too will probably replace the drivers some day since I don't like any of

them and mine are not in good shape as far as the finish goes.

It was meant to be a general light-hearted comment, Pete. It wasn't directed at your last post.

I'm not a big 2ax fan either, nor am I anyone to talk, as I destroyed a pair of 2ax's in a MUCH less sophisticated manner 25 years ago, when all they needed was some pot cleaning (yeah, those things were trouble even way back when)! Hey, I could have used your advice, but you never returned my phone calls . I agree, this isn't the place to discuss it. I would be too embarrassed.

Roy

[Guest kevemaher]

Hi Pete B and RoyC,

I've thoroughly enjoyed this discussion.

I started out this summer buying a bunch of the old classics on eBay as something to do as I recovered from surgery. I have pairs of the Dynaco A35, Large Advent, and both the "Old" and "New" AR-2ax. As you know, these can be had for a song. The shipping to out here in the hinterlands is more expensive than the speakers are. I prefer the Dynaco A35s and have them set up now in the "Audio" room, while I build my masterpiece. GF not allowed in.

I started out with the usual AR restoration things... pots, caps, new finish, new grill covers, re-surround the woofers. At each stage, I was encouraged by those on this forum and by the results. I became more emboldened. I learned more about drivers and integration, got some test equipment, and finally started replacing drivers in the "New" AR-2ax box for fun.

I'm fully recovered and now have less time for this hobby. But yesterday I bought some 3/4" MDF. I'm thinking about ripping out the baffle board and putting the drivers where I want them in a new baffle board. Maybe, I'll just learn how to build myself a box, drop the drivers in, and paint it black. It may look ugly, but it will probably sound great. I will find a place somewhere on the boxes for the AR badges.

I have strayed so far from the intent of this forum, in fact so far from the intent of this entire web page that this discussion needs to be ended or moved elsewhere. I'd be glad to continue correspondence via email.

I heartily thank all of you who have helped me along each step in this journey. I have great respect for all of you. This website is a wonderful place for learning and sharing.

Kevin

[genek]

Your comment regarding the location of your original post is spot on. Suggest future posts on your project (if any) be done in the mods and tweaks area as you mentioned. Restorers tend to want only restoration & vintage related posts to reside in the speaker named discussion areas.

Speaking as someone who has bullheadedly preserved an original pair of AR-2ax's for 28 years and counting, I think it's worth keeping in mind that (1) AR sold a huge quantity of these over the years, so a few mod-and-tweakers are hardly likely to hasten the extinction of them as a vintage type, and (2) original drivers are fast becoming unobtainable (if they haven't already), and sooner or later all of us who own these speakers will find ourselves forced to choose between selecting different components for them or scrapping them. I for one am very interested to hear what contemporary components people are having success installing in the old boxes, particularly those of you who are taking the time to take measurements and do listening comparisons against the original configuration.

Maybe someday someone will take on a project that ends up duplicating the sound of the original speaker with modern components; will we call that "mod" or a "restoration?"

[Pete B]

It was meant to be a general light-hearted comment, Pete. It wasn't directed at your last post.

I'm not a big 2ax fan either, nor am I anyone to talk, as I destroyed a pair of 2ax's in a MUCH less sophisticated manner 25 years ago, when all they needed was some pot cleaning (yeah, those things were trouble even way back when)! Hey, I could have used your advice, but you never returned my phone calls . I agree, this isn't the place to discuss it. I would be too embarrassed.

Roy

I saw your smile emoticon but with the general attitude here it's hard to tell ...

I do remember you mentioning those 2ax's some time ago.

[Pete B]

Speaking as someone who has bullheadedly preserved an original pair of AR-2ax's for 28 years and counting, I think it's worth keeping in mind that (1) AR sold a huge quantity of these over the years, so a few mod-and-tweakers are hardly likely to hasten the extinction of them as a vintage type, and (2) original drivers are fast becoming unobtainable (if they haven't already), and sooner or later all of us who own these speakers will find ourselves forced to choose between selecting different components for them or scrapping them. I for one am very interested to hear what contemporary components people are having success installing in the old boxes, particularly those of you who are taking the time to take measurements and do listening comparisons against the original configuration.

Maybe someday someone will take on a project that ends up duplicating the sound of the original speaker with modern components; will we call that "mod" or a "restoration?"

You make a lot of sense here, there is no reason to stop this thread. The mods can move it if need be.

[Pete B]

Hi Pete B and RoyC,

I've thoroughly enjoyed this discussion.

I started out this summer buying a bunch of the old classics on eBay as something to do as I recovered from surgery. I have pairs of the Dynaco A35, Large Advent, and both the "Old" and "New" AR-2ax. As you know, these can be had for a song. The shipping to out here in the hinterlands is more expensive than the speakers are. I prefer the Dynaco A35s and have them set up now in the "Audio" room, while I build my masterpiece. GF not allowed in.

I started out with the usual AR restoration things... pots, caps, new finish, new grill covers, re-surround the woofers. At each stage, I was encouraged by those on this forum and by the results. I became more emboldened. I learned more about drivers and integration, got some test equipment, and finally started replacing drivers in the "New" AR-2ax box for fun.

I'm fully recovered and now have less time for this hobby. But yesterday I bought some 3/4" MDF. I'm thinking about ripping out the baffle board and putting the drivers where I want them in a new baffle board. Maybe, I'll just learn how to build myself a box, drop the drivers in, and paint it black. It may look ugly, but it will probably sound great. I will find a place somewhere on the boxes for the AR badges.

I have strayed so far from the intent of this forum, in fact so far from the intent of this entire web page that this discussion needs to be ended or moved elsewhere. I'd be glad to continue correspondence via email.

I heartily thank all of you who have helped me along each step in this journey. I have great respect for all of you. This website is a wonderful place for learning and sharing.

Kevin

Hope your surgery was nothing too serious.

Have you seen these small boxes, I'm thinking for the Mid/Tweeter section only:

http://www.partsexpress.com/webpage.cfm?we...ectGroup_ID=603

[Guest kevemaher]

Hi Pete,

Yes, I've seen these boxes. I'll still need to reduce the volume with blocks of MDF, but it is a good starting place. I could also buy one of their woofer boxes.

I've cut some MDF braces and baffle boards. Confidence in box building is increasing.

I will get my Scanspeak woofers next week and characterize them in the AR-2ax box. Then go from there.

Thanks again for all your encouragement.

Kevin