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 Post subject: Dynaco mono-block amps/trash or treasure? please help!
PostPosted: Oct Mon 09, 2006 12:29 am 
Hi folks,My father brought me home a pair of what I believe to be Dynaco power amps from the local land fill.They appear to be in very nice shape and are complete.However,I'll be damned if I can figure out what model they are.I can't find any writing on the chassis and none of the pictures I found match.
Each amp has a Dynaco A-420 audio output transformer and a Stancor PC8422 power transformer.There are two 6cz5 power tubes and one 6an8a preamp tube per block.I assume the rectifers are solid state for there seems to be no tube for that purpose.The 6an8a tubes reside on a small circuit board inside of a liitle cage drilled with holes.
Unlike the othe Dynaco amps I have seen ,these do not have a cage over the entire top.Instead they have a flat square metal panel screwed to one side.This does not look like a homemade addition.Maybe these slid into a cabinet?The rear aprons look like the othe Dynacos with the octal socket,speaker coonector screws and so on.
With two 6cz5's in push pull I would think maybe about 20 watts out per amp?I could take a few digital pics if any body cares.Any thoghts would be greatly appreciated.Thanx much. :D


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 Post subject:
PostPosted: Oct Mon 09, 2006 12:34 am 
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Hi. I'd be interested in seeing pictures of top, front, back, and bottom the the amps. Dynaco made some good quality stuff, but, I'm not saying that's what these are. Right now, I don't know. Thanks. Bill Cahill

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PostPosted: Oct Mon 09, 2006 12:41 am 
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Two things come to mind.

First, Do Not get rid of these amplifiers!!

Second, we will do research and let you know what they are.

And even though I only mentioned two things, the third thing is: One of us would probably want to take them off of your hands if you are inclined to not want them!!!!!!!

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 Post subject:
PostPosted: Oct Mon 09, 2006 2:31 am 
Don,if you would like to see some pics of these amps,e-mail me at:contactmpc@msn.com.I took some a few minutes ago and sent them to Don.Thanks for your interest.Mike :D


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 Post subject:
PostPosted: Oct Mon 09, 2006 2:34 am 
Wow,I need to go to bed.I meant I sent them to Bill.I'm sure you'll forgive me.Thanx.


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 Post subject:
PostPosted: Oct Mon 09, 2006 3:01 am 
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Post the pictures here so everybody can see them.

Dave


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 Post subject:
PostPosted: Oct Mon 09, 2006 3:18 am 
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Are you in the Philadelphia area? These could have been made from leftover Dynaco parts when the company changed hands. I don't think that a stock Dynaco would have used a Stancor transformer.

Any date codes on the parts and tubes?

Since "factory-wired" Dynacos were farmed out to moonlighting Drexel students (as I recall the story), who knows what might have been created by someone with access to certain Dynaco parts.


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 Post subject:
PostPosted: Oct Mon 09, 2006 1:32 pm 
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Location: Wisconsin
I've done a little cursory web-searches that imply a few things:

1. Dynaco A420 output transformers are good for around 60W and they have a primary impedance of 6600 ohms.

2. Some companies bought Dynaco transformers for use in their own amps.

So, you might have a Dynaco amp, you might not. I lean towards not, because I've seen most of them, and what you have is totally unfamiliar to me. I bet you could built a nice amp if you didn't want to rebuild what you have.

Tom


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 Post subject:
PostPosted: Oct Tue 10, 2006 3:52 am 
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My 1963 Allied Radio catalog lists a series of Dynaco "super fidelity" output transformers, ranging from the A-410 (8000 ohms) to the A-450 (2200 ohms), including the A-420 (6600 ohms). Unlike the A-470 used in the Dynaco Stereo 70 (also listed in the catalog, along with a smorgasbord of tube audio and other such vintage goodies), these transformers are potted. Also, most of them are more expensive than the other brands of output transformers listed in the catalog (Stancor, Triad, etc.).
-Adam

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PostPosted: Oct Wed 11, 2006 7:21 pm 
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If you decide to get rid of the amps I'll take them :mrgreen:


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 Post subject:
PostPosted: Oct Wed 11, 2006 9:19 pm 
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Those are nice transformers, capable of 60 watts. I would modify those amps to use a better tube such as 6L6GC or EL-34. A nice find :)


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