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Dynaco A25 vs A35, why the different xover point?

elitopus

elitopus

Addicted Member
I just picked up a pair of A35. They have a 8uf cap. Doing rough estimates thats around a 2.5khz xover point.

The A25 has a 5uf cap. Using the same calculations they would have around a 4khz xover point.

Both speakers use the same woofer and tweeter. The only real difference is the A35 are larger and uses a sealed cab. The A25 is smaller and an aperiodic cab

Both speakers allow the woofer to run wide open. So in theory there is more woofer/tweeter overlap in the A35. Is that why they don't sound as good?

Testing my single complete A35 (other one needs a tweet), it doesn't sound as nice as the A25's I had before. It could be because I am not doing a direct comparison. Also it could be because I am so used to horns and have not listened to a more laid back speaker in a while.

I am going to get some 8uf oil caps and see how that changes the A35. It would be interesting to put something closer to 5uf in there just for testing. They might have that A25 "magic"
 
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I believe the A35 cabinet is divided internally and has an aperiodic port between the two "halves". This A35 arrangement might either roll off the woofer top end sooner or emphasize the bottom end.

Either way, the lower crossover point might be compensating for this.
 
Yes the cabs are divided like that. I put a pic up in my other Dynaco thread. Its an interesting arrangement. And you are right, the woofer probably behaves differently because of it.

Since poly caps are so cheap, I will pick up some 5.1, 6.8, and 8.2uf caps and see what the difference in sound is.
 
FWIW, I had a pair of A35s years ago and always thought they sounded fuller and richer than the A25s, which were no slouches either. No science behind that thinking, but the difference was more than subtle to me. Kinda like the difference between KLH Sixes and Twenty Threes. Just my .02. It would be interesting to hear the difference between caps.
 
Looking closer at the original cap I'm pretty sure its an electrolytic. I'm curious how much the voicing would change by putting in a poly. IMG_8082.JPG

Maybe I'll get a few lytics with my order and compare those too.
 
alteclipsch said:
FWIW, I had a pair of A35s years ago and always thought they sounded fuller and richer than the A25s, which were no slouches either. No science behind that thinking, but the difference was more than subtle to me. Kinda like the difference between KLH Sixes and Twenty Threes. Just my .02. It would be interesting to hear the difference between caps.
Click to expand...

I wish I had the A25 and A35 at the same time so I could compare them.

Back when I had the A25 I was into the more laid back, east coast sound. I had AR4x, A25, and OLA's.
Now I am so used to the more forward sounding horns. The A35's sound kind of dull to me. It could be caps or it could be my ears are just used to Altecs.
 
jim t said:
The A25 and A25XL used different caps. maybe one of your speakers is an XL?
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Both of mine are A35. They are much larger than the A25xl and also mine are sealed box.

Also both of mine have identical 8uf caps. They were built about 6 months apart in 1974
 
A25XL uses the SEAS H086 driver, crossing with an 8mfd cap and a coil (12db per octave slope).

Wayner
 
elitopus said:
The A35's sound kind of dull to me. It could be caps or it could be my ears are just used to Altecs.
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Having Altecs makes it difficult to judge nearly anything, IMO. Vals are my go-tos, although the KLH Fives do a very nice job on the highs. I think caps in your A35s will open them up.
 
elitopus said:
I just picked up a pair of A35. They have a 8uf cap. Doing rough estimates thats around a 2.5khz xover point.

I am going to get some 8uf oil caps and see how that changes the A35. It would be interesting to put something closer to 5uf in there just for testing. They might have that A25 "magic"
Click to expand...
And no report back on the cap experimentation?!
 
VBB said:
And no report back on the cap experimentation?!
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I'd like a report, too. Although I no longer have the A35 (I foolishly gave them to a friend who let his idiot kid overpower them and froze the woofer voice coils), I remember how nice they sounded.
 
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alteclipsch said:
I'd like a report, too. Although I no longer have the A35 (I foolishly gave them to a friend who let his idiot kid overpower them and froze the woofer voice coils), I remember how nice they sounded.
Click to expand...
I just recapped mine. The old Jensen 8 uF caps had drifted to 9.3 and the speakers sounded ok...a little muddy. I threw in some new 8.2 uF Dayton film caps I had and it definitely opened them up. The separation of instruments improved, and the lows (after I got used to hearing it - brain plasticity) were definitely lower and clearer. It seemed to stretch the range. Lower, well defined bass notes and higher clear highs. But what this did was move the midrange to a different dominant note than my two pair of A25's. They still have a similar Dynaco sound, but at the same time, different. I had to turn the control knob on the back down to the lowest, or second lowest setting to attenuate the highs. Otherwise they seemed too bright. This was tested on an Onkyo Integra SS receiver, but I'm gonna also check them on my tube setup before any changes.

I'm really curious what a new 'lytic cap would do, and what a lower uF cap would do.
 
Alas, another incomplete thread on A35's...I will keep digging in this graveyard. Otherwise, I am ordering both 8uf and 5uf caps to test it myself.
 
Have been an Dynaco speakers fan for decades. Have had all 4 sizes, A-10, A-25 (2 pairs), A-35, and A-50 (sold them recently, foolishly). But never seriously compared them until my hearing suffered serious deterioration. It was then when I became curious as to how they compare. I needed a judge! My sister stepped in to help. She plays piano and is very sensitive to the quality of music, and by extension, the quality of music reproduction. She likes A-35 the best. It is the clear winner, no hesitation at all.
 
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