One Dynaco A-35 recapped - sounds the same to me

I started recapping some recently acquired A-35s yesterday. Ordered the new caps without opening them up and assumed all I needed was a 5 uF cap in each. Was wrong, they each take an 8 uF cap.

So, was able to scrounge thru my parts box and find 3 caps that summed to 8.1 uF. Installed the trio and then A/Bed the recapped speaker with the all original one. Honestly, I can't hear much, if any, of a difference between the two. This was also the case with the pair of A-25s recapped last year. Wonder why this is? :scratch2:

I've refurbed KLH 17s/6s/OLAs, etc., that the recapping made a huge difference in the highs. If fact, some of them sounded like the tweeters were not even working before the recap.

Another observation on Dynaco speakers........the baffles in them are made from some crappy chip board (same is the case with some KLHs). Had to install longer screws to get the woofer to snug up tight against the new foam gasket.

The woofers in Dynaco speakers are featherweights too. How do they make as much bass as they do??!!

All in all, I think Dynaco speakers sound pretty good for what folks typically pay for them. Above are just some observations from my dealings with them.

If you're over 45, your hearing likely drops off somewhere in the middle of that tweeters range... Unless the old cap is entirely shot, replacing it makes only a subtle difference that is possibly lost on you.

Find someone with young ears and let them have a listen...

Also, old speakers likely don't perform to orig spec anyway.

BmWr75 said:

How do they make as much bass as they do?

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"The patented aperiodic (essentially non-resonant) woofer design utilizes a highly damped vent (not a reflex port) whose acoustic resistance is very carefully controlled. Its high friction venting action lowers the "Q" of the system and reduces the impedance variation near resonance in Dynaco speakers to 2:1, contrasted with 400% or greater variations in most systems. The advantages are smoother response with better bass definition and reduced Doppler distortion, plus more efficient amplifier power transfer (Dynaco speakers can sound louder than others of the same efficiency from a given amplifier), since the amplifier works into a more nearly resistive load."

Recently acquired a pair of A-25. Have not ventured inside yet, but the project is looming. Recapping was going to be my primary objective. I find your observations interesting.

jn229 said:

Recently acquired a pair of A-25. Have not ventured inside yet, but the project is looming. Recapping was going to be my primary objective. I find your observations interesting.

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A-25s take a 5 uF capacitor.

Well, at least it's not a huge investment. I could hear a difference in my A25's and most all the other speakers I've done, too.

The speakers are "featherweights" because they use Alnico magnets, instead of the heavier ceramic magnets.
In 2x12 a guitar cabinet, a pair of 11 oz. alnico magnet speakers are FAR lighter, than a pair of 40 oz. ceramic magnet speakers.

Steve

A 25 XL's take an 8uf cap.

BmWr75 said:

A/Bed the recapped speaker with the all original one. Honestly, I can't hear much, if any, of a difference between the two. This was also the case with the pair of A-25s recapped last year. Wonder why this is? :scratch2:.

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You know the drill, MEASURE.

A-25s before and after recapping are shown here, #1 vs. #6. You may have to Photoshop or print on velum to see the difference, if any. That wasn't what we were looking at, but the data is there:

http://www.audiokarma.org/forums/showthread.php?t=162000

Two reasons why it might not make a difference:

1) The original caps were still fine. I usually measure them after removal to check.

2) The caps are merely performing a minor response "shaping" function in the circuit, with driver rolloff in primary control. Again, measure to know....

Measure the old 8 uF cap to currently be at 12.0 uF just a few minutes ago.

Checked my meter with a new 5.1 uF cap, the meter is dead on.

Frequency response measurements forthcoming, probably tomorrow, from my far from anechoic mancave.

BmWr75 said:

Honestly, I can't hear much, if any, of a difference between the two. This was also the case with the pair of A-25s recapped last year. Wonder why this is? :scratch2:

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It's possible that the old caps were functioning just fine.

Cut-Throat said:

It's possible that the old caps were functioning just fine.

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Maybe.........but the one I measured was +50% out of specification.

Measurements

Here's the frequency response measurement comparison - A-35 that still has the old 8 uF capacitor in it and its sister with a new 8.1 uF capacitor installed.

Green trace = new capacitor
Blue trace = old capacitor

Measurements taken at 3' on-axis with tweeter using Behringer ECM-8000 mic, TASCAM US-144 USB preamp, and REQW software. This is a new equipment set up for me and I finally got the Audigy 5 soundcard in my PC calibrated using the loop back method. I still think these measurements are suspect though.....it's hard for me to believe the nearly 35 db spread in these measurements.

Input on what I might be doing wrong from anyone using this equipment set up is welcome. Paratima??

OK, here's the same two Dynaco A-35s measured the old fashioned way....using individual test tones and plotting the data in Excel. This for sure confirms to me REQW is not working right, probably some error on my part in setting up the software or performing the calibrations.

To me, the graph confirms recapping this speaker did little to changes its sound, even though the cap that was removed as 50% out of specification (8 uF nominal, measured 12 uF actual). Of course, I've not actually measured the old cap in the speaker that has not been recapped, so I don't acutally know for sure it is 50% our of spec. too.

I'd still change the caps in the other speaker and then forget about it if your ears can't tell a difference. Changing the caps isn't a sure way to better the sound on every speaker as Zilch said. Since speakers are the primary variable in your sound it's still a good idea but taking a look at the caps in a given component can tell you the shape they are in, dried or swollen. If they look fine and everything is working well I don't mess with them in a receiver, amp, etc. It might be a good idea to prevent future issues but I'll cross that bridge when I come to it. Replacing all the caps in a receiver for refurbishing purposes when it is working fine is a bit of overkill to me, though some may not think so. Anyway I know I got off track so I'll stop.

I replaced the caps in my A-25s with Solens and found there to be no difference. When I replaced them with Jantzen Superiors I heard a noticable improvement.

Some crossovers just don't improve no matter what brand of cap is installed. Maybe those are the well designed ones.

hoaryhag said:

I'd still change the caps in the other speaker and then forget about it if your ears can't tell a difference.

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I'll recap the other speaker just for good measure. Just wanted to share my experience with recapping the simplistic crossovers in Dynacos.

Urizen said:

"The patented aperiodic (essentially non-resonant) woofer design utilizes a highly damped vent (not a reflex port) whose acoustic resistance is very carefully controlled. Its high friction venting action lowers the "Q" of the system and reduces the impedance variation near resonance in Dynaco speakers to 2:1, contrasted with 400% or greater variations in most systems. The advantages are smoother response with better bass definition and reduced Doppler distortion, plus more efficient amplifier power transfer (Dynaco speakers can sound louder than others of the same efficiency from a given amplifier), since the amplifier works into a more nearly resistive load."

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Interesting, I'll have to take a deeper look into this. Thanks for the info.


So you are saying you got a better sound out of your Dynaco's with a different brand cap Jallenbass?

hoaryhag said:

Interesting, I'll have to take a deeper look into this. Thanks for the info.


So you are saying you got a better sound out of your Dynaco's with a different brand cap Jallenbass?

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That's correct. Also, while the Jantzen Superiors work great on my Dynacos and BA A100s they don't work so well on my BA A70s, Baby Advents or DCM Timeframe TF-250s. That for me is the fun part. Trying different things to see what works best.