Dynaco A25 Musings

I always wanted a pair of these, and Retro Stereo had a very nice pair that I talked him out of at this year's AK Fest. We played them while we were there, and my impressions were that they are a bit muddy, and what highs were present, were so narrowly focused that if you weren't sitting in exactly the right position you might as well turn the speakers to face the wall, 'cause you aren't gonna hear the upper octaves.

I brought them home, and after I got some projects out of the way so I'd have some time to really evaluate them, I hooked 'em up to the Kenwood KR-9600 for an extended listening session. Unfortunately, this session was rather short, as one tweeter wasn't working. No fooling with the tweeter level control made any difference. As I was getting up to shut the whole system down, a 'pop' came from the errant speaker, and the tweeter started working. OK...so I've got an intermittent tweeter. Not exactly a tear-jerker, since I'm pretty unimpressed with the stock Seas 87H tweeter anyway.

Apparently, the recommended replacement tweeter is the Seas 27TFFC. The horizontal dispersion plot of this tweeter just didn't impress me, so I looked at other Seas models, and decided on the 27TBFC/G, which also has a metal grill to protect the tweeter dome, simlar to the original. I also ordered a couple of Solen 5.1µf 400V film caps to replace those sad original electrolytics.

The stock 'crossover' for an A25 is nothing more than a 5µf non-polar electrolytic cap to protect the tweeter from the bass. Nothing more. This further enforces my belief that the choice of tweeter is highly subjective, since there isn't a complex network matched to the tweeters' parameters. I've also heard others talking about the stock inductor for the woofer...this A25 has none. The woofer is run wide open, and only natural rolloff is relied upon.

Did I mention getting the grills off of these sucks? :bash:

Anyway, parts came in yesterday, and I pulled these apart and replaced the crossover cap, and also replaced the wiring to the woofer (the stock wiring must be 24ga...tiny stuff). The tweeter wiring was left alone. Cleaned the tweeter level control with some ProGold, and reinstalled all the drivers, itching the whole time from the nasty ancient fiberglass insulation. Ick... The new tweeter lines up 'close enough' with the stock screw holes to get it installed, but the hole in the cab had to be enlarged in two places to make room for the new tweeters' terminals...a 5 min job with a file.

Now the speaker sounds like something worth listening to. The bass and mids were always decent, but the highs now join them. The new tweeter is a perfect match...not compared to the old tweeter, but to the old woofer and crossover. With the tweeter level control all the way up, the speaker is a little too bright. With it set to what is labeled as 'Normal', it is just about perfect.

These things aren't never gonna rock the house, but are great for a bedroom or den setup. While they do an amazing job, especially considering the tiny size of the original voice coil and magnet on the Seas woofer, they haven't come close to changing my opinion that modern speakers kick the snot out of 98% of the stuff built before 1980 But -- with these mods done they are more than listenable. Certainly I'm of the opinion that the Seas 27TBFC/G is a very good choice for replacing the original tweeters.

Cost of mods? About $80, a couple of hours, and a lot of itching.

Very interesting.
Thanks for sharing.

I have a couple pairs of A25s and A50s.
The 25s serve as garage speakers and the 50s kinda just "hang out" in my collection.

When I first tore apart a pair of 25s, my impressions were similiar to yours.
WTF...
What is this chincy crap?
Heh heh.
I mean, damn.....these things sound pretty good for what they are.
Which by all definitions, isn't too much.

So, you say this mod is working well... huh?
I might give 'er a try, myself.
Sounds worthwhile.
No pun intended.

Regards,
John

EW

Is it worth changing out crossover with original tweets?
May be another project for the funnel.

Jim

All the 'crossover' consists of is a very crappy bipolar electrolytic cap, and yes, it ought to go bye-bye. If you change the tweeter and not the cap you are wasting your time. At a minimum, change the cap. The tweeter may sound perfectly acceptable to you once that it done. I didn't have that luxury, since one tweeter was already flaky.

Damn! I thought mine sounded pretty good. Guess I`d better put them out on the curb for pick. Damn! I`m very disappointed. ****!

TankDonovan

...and I know you're kidding.

My opinion is just that. Holds no more weight than anyone else's, and certainly a lot less than your own.

But if you'd like to hear a nice improvement, dump that stock crossover cap.

I've got a three cap twist from Kegger sitting on my bench waiting to get installed into mine. Some poly props with a Dayton bypass cap so it's a nice upgrade.

FWIW, I think they sound pretty good right now, but then again, I prolly can't hear zilch above 8K. I'll mess with them this weekend and let you know what I think.

Yes...,[EchoWars]I`m kidding. I don`t know anything about replacing crossover caps. I wish I did. And I love to hear different opinions. You sound like you really know what you are talking about.

I have heard somewhere[AK?] that replacing the caps and tweeters made great improvements. I could change the tweeters but I don`t know about the caps.

TankDonovan

tankdonovan said:

I have heard somewhere[AK?] that replacing the caps and tweeters made great improvements. I could change the tweeters but I don`t know about the caps.

TankDonovan

Click to expand...

I dunno Tank, lots of them one cap crossovers are just an axial cap on the (+) line to the tweeter.
Snip it out and splice in the fresh one and you're done! :yes:

Now that everyone knows how bad these little speakers are, I suggest you send any you might have hanging around to me.

EW, I'm not saying you're wrong. I have two pair of Advents with exactly the same drivers and crossovers and they sound completely different. I don't know why there is any difference, but it's clear to anyone. So I suspect you just got a bad pair. I love my A25s. I once a/b them with my DCM Time Windows and thought they held their own against a speaker many times their size and price. My daily drivers are a pair of a/d/s L810s and while the little Dynacos can't hold up to them, they don't stack up too poorly.

In my opinion, the highs are really nice and deffinately there. They don't extend to the moon, but there is more than enough there. I find the mids to be nothing but sweet. They don't go all the way down to the basement either, but for their size, the bass is outstanding I think.

I dunno. I think I'll have to drag them to the upcoming Colorado AK get together and see what the rest of the gang thinks.

Take care,

Ed

The crossover cap may have been in worse shape than most in my pair, and since one tweeter was already bad, I had no chance to listen to it with a good cap and the old tweeters.

Still, a bipolar electrolytic cap has no place in this speaker, regardless of whether the tweeter is considered up to the task at hand or not. Even if I had been pleased with their performance before my 'mods', I'd have dumped the stock cap.

Fast_Eddie said:

Now that everyone knows how bad these little speakers are, I suggest you send any you might have hanging around to me.

EW, I'm not saying you're wrong. I have two pair of Advents with exactly the same drivers and crossovers and they sound completely different. I don't know why there is any difference, but it's clear to anyone. So I suspect you just got a bad pair. I love my A25s. I once a/b them with my DCM Time Windows and thought they held their own against a speaker many times their size and price. My daily drivers are a pair of a/d/s L810s and while the little Dynacos can't hold up to them, they don't stack up too poorly.

In my opinion, the highs are really nice and deffinately there. They don't extend to the moon, but there is more than enough there. I find the mids to be nothing but sweet. They don't go all the way down to the basement either, but for their size, the bass is outstanding I think.

I dunno. I think I'll have to drag them to the upcoming Colorado AK get together and see what the rest of the gang thinks.

Take care,

Ed

Click to expand...

Hey Ed,
I've heard a few pairs of the Dynaco A-25's and I don't think EW got a bad pair, I just think he made a good pair "better". You have to remember, EW's new favorite pair of speakers are Army's pair of Infinity RS 2.5s, and if you want to hear some multiple-driver extension, check out a pair of those sometime. Once you find the "Holy Grail" of speakers, most of the others end up being just silver cups, good and very "listenable", but not the "Prize".
Just my $.02 of course.

Glenn, I'm glad you got those speakers to where you're liking them and I'm glad I could help.


Retro

No two pairs of ears hear the same thing. Vive le difference..........

tentoze said:

No two pairs of ears hear the same thing. Vive le difference..........

Click to expand...

Yep.

I have seen some old speakers where the dome tweeter works but the output is just way low compared to what it was. I have 2 pair of A25s I got from my brother. They were both very gently used and sound wonderful with the original tweeters and crossovers. What I did find was that if you remove the friggin' metal cover ont he dome tweeter, you get rid of all kinds of nasty diffraction. Then you apply a ring of foam weather sealing tape, or thick felt, around the perimeter of the dome to further reduce diffraction. This leaves you with a better sounding speaker, with great imaging. Read about the foam trick in Audio. God, I miss that magazine...

EchoWars said:

The crossover cap may have been in worse shape than most in my pair, and since one tweeter was already bad, I had no chance to listen to it with a good cap and the old tweeters.

Still, a bipolar electrolytic cap has no place in this speaker, regardless of whether the tweeter is considered up to the task at hand or not. Even if I had been pleased with their performance before my 'mods', I'd have dumped the stock cap.

Click to expand...

I haven't yet recaped mine, but I did recently put new caps in a pair of old Altecs for a friend. Couldn't believe the difference. I'll do the A25s in short order.

Take care,

Ed

When I said chincy crap, I was being kinda sarcastic.

I guess I should have mentioned that the reason I have 2 sets of A25s and A50s in the first place is because I was impressed by the sound/build quality from the start.
Plus, i'm a Dynaco fan, anyway...so it made sense to get them.

Needless to say, after hooking them up to at least 15-20 source/integrated/pre-pro combos, I decided to tear them apart to see what these bad puppys had.
That was my first set.
The other 3 came after the fact.

I guess I was expecting more than what there was.
That's all.
Which is all good, because in my heart....i'm a Klipsch fan, and that is their forte.
Getting the most out of the least.

With the Dynacos.
You really do get the most for the least.
IMO. just some plain ole' fine engineering.


Regards,
John.

21 posts since Dec 2003. Kinda shy are we, John?

Oh, and I like my A-25s. I think I will order some new caps, though.

Once you have your's open, I'd be curious as to to the size of the cap you find. As I stated, mine had 5µf caps, and were replaced with 5.1's.