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Dynaco A35 Xover and Caps


Guest kevemaher

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Guest kevemaher

I just received a pair of Dynaco A35s that I bought on eBay (actually the seller advertised them as A25s, but I'm not complaining). I just hooked them up and they sound great. All drivers work. These were made in Denmark. They have a 5 position tweeter level control.

My questions are:

1. Where can I find a crossover schematic?

2. Should I replace caps (and resistors)? Suggested types and brands? How hard is it to remove the woofer?

Thanks,

Kevin

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>I just received a pair of Dynaco A35s that I bought on eBay

>(actually the seller advertised them as A25s, but I'm not

>complaining). I just hooked them up and they sound great. All

>drivers work. These were made in Denmark. They have a 5

>position tweeter level control.

>

>My questions are:

>

>1. Where can I find a crossover schematic?

>2. Should I replace caps (and resistors)? Suggested types and

>brands? How hard is it to remove the woofer?

>

>Thanks,

>

>Kevin

Hi Kevin;

Here is a front and rear photo of a pair of Scan Dynaco A-25 crossovers.

This is from a Scan speaker pair, rather than from a more common Seas, note the factory printed, "Made in Denmark", rather than the later rubber stamped version.

No serial number may mean that they were on separate cabinet mounted labels rather than stuck on the terminal strip just below the terminal connectors.

A-25 and A-35 are the same crossovers and used the exact same drivers.

The A-10 used the same tweeter and a smaller woofer, a more elaborate crossover, but no switch, the A-50 used a slightly more elaborate crossover, same tweeter and 15 ohm woofers.

The 10" woofers were made with a quality cast aluminum frame only, with and without perimeter horns at the screw hole locations.

The main differences are, the A-35 is slightly larger cabinet, is internaly vented, rather than using an external port, and supposedly, judged by the golden ears, a slightly smoother midrange, than the A-25.

I wouldn't stay up all night wondering which is the better speaker, yours are just fine.

Note the yellow block cap is a replacement, possibly, as in, not the usual Jensen NP tubular cap used during production of the classic Dynaco speakers.

The next two photos are from ebay and are of A-25 Seas crossovers.

Note the serial number sticker on the paper label and hand stamped, "Made in Denmark".

The last one is a A-25 schematic from our very good member, Pete.

My advice is, if they sound good, do not even attempt to remove the grille cloths.

If you have a sonic problem, we can help you down the road.

A very good speaker as is, enjoy, Kevin.

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Guest kevemaher

Vern,

Thanks for all the great info, pics, and schematic! I've read somewhere that the A35 used an 8uf cap, instead if the 5uf cap in the A25.

I removed the grills (easy with velcro) because I'm pretty curious. I had researched Dynaco speakers prior to getting this pair on eBay and wanted to see the physical condition of the drivers. This is how I found out they were A35s (S/N 27-451897 and 27A451323). All 4 drivers are in great shape.

I have recently repaired 2 sets of AR-2ax speakers. I replaced the caps and pots, re-did the surround on the foamed pair and replaced a blown tweeter and mid-range. Both sets sounded a lot better afterward. So I'm comfortable with working inside speaker enclosures.

I've listened to these A35s for a few days now and they do sound great. Not as boomy as the AR-2ax. I'm wondering if they would sound even better if I replace the old caps since I know that caps deteriorate with time (sigh, just like us all). One cap on my 19 year old Bryston 3B just died (but will be replaced under warranty!).

Best,

Kevin

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  • 1 year later...
Guest The Groke

Hello, If possible, I would love some info on how to best remove the grill cloth and on how to best get to the crossover components in the Dynaco A-25s. I can see from the pictures that it is nailed into the case from the inside. I just can't figure out how to get the grill off without destroying them.

Thank you in advance..

DT

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  • 1 year later...

Thanks a lot for the schematics, I've got a pair of xtra-nice A-25 except one loose binding post and Bob Latino suggest replacing the 5uf caps with good ie: AuriCaps 4.7uf and .22uf in parallel (for 4.92uf) haven't done it because they sound very good as they are.

I did remove the grills without much problem try to twist off the logo carefully (it was factory glued to the screw) remove the screw that's exposed then using plastic and tongue depressor (wood) "pry bars". I used a different color to match the room for the CEO. but the fabric from the local yardage store was very close to the same. And frankly scarlet I don't give a ... dang.

I used Amazing Goop glue to attach the fabric, it works like a super thick contact cement. I put the screw back into the face so I wouldn't loose it and just glued the Dynaco Logo directly onto the cloth so I can take off the grill easily. My fabric was the perfect thickness so the grills are a perfect press fit and the glue still on the cabinet isn't very sticky anymore (it's amazing it's sticky at all after 40 years!)

FYI: these speakers were designed to be on the floor and against the wall for best base response.

David

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  • 3 weeks later...

I have 2 pair of A25's that I thought sounded great. Both improved with recapping. Another thing to look for is degraded MDF on front baffle where woofer screws attach. Bot my pair were spinning freely though the goop they used in factory kept them firm in place.

I ended up glueing pieces of plywood behind the MDF to give the screws someting to bite into - idea care of Zilch. I recapped second pair using Daytons + Russian Military bypass 0.047's. Also updaed those tiny binding posts. That's my best sounding pair. I think the binding posts made the difference.

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