Dynaco Mark III / #124 inspired preamp layout

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BobW
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Dynaco Mark III / #124 inspired preamp layout

Post by BobW »

I recently bought a Dynaco Mark III for next to nothing. After repairing the amp, I created a preamp layout loosely based on the #124 ODS. The tone stack is actually closer to an Allen than a Dumble, and derives it's B+ and heater voltages from the power amp. However the preamp heaters will be dc voltage. The preamp build is only about 20% complete so there may be a bit of adjusting, but so far has been a fun project. the end result may not sound like a Dumble at all but time will tell.
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BobW
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by BobW »

Parts arrived last night, and will report back the build results
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Structo
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by Structo »

Cool!
I'd love to find one of those old amps or a pair would be even better.
Tom

Don't let that smoke out!
BobW
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by BobW »

Yeah finding a pair would make me reconsider them as a stereo amp not a guitar amp.
tictac
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by tictac »

Sorry but I have to tell you this story...

I few years back I was at a garage sale and I bought this huge wacky 2 piece 60's console stereo because it had some cool Jensen speakers and a built in reel 2 reel and a turn table I figured I could sell on Ebay. (paid 125.00 for this hernia builder)

When I went to load this monster in my truck I noticed there were wires connected to the console going into the wall through a hole poked through the sheet rock. I asked the lady if I could see what was on the other side of the wall connected to the wires. She opens a closet door and lo & behold there was a pair of Dynaco MK3's with the original KT88 power tubes.

I sheepeshly ask her, how much do you want for those? When she said, "Oh you can just have those for free" I realy pooped myself but needless to say I removed them quickly from the premises before she changed her mind...

They were great sounding amps; nice Iron...

TT
BobW
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by BobW »

tictac wrote:Sorry but I have to tell you this story...

I few years back I was at a garage sale and I bought this huge wacky 2 piece 60's console stereo because it had some cool Jensen speakers and a built in reel 2 reel and a turn table I figured I could sell on Ebay. (paid 125.00 for this hernia builder)

When I went to load this monster in my truck I noticed there were wires connected to the console going into the wall through a hole poked through the sheet rock. I asked the lady if I could see what was on the other side of the wall connected to the wires. She opens a closet door and lo & behold there was a pair of Dynaco MK3's with the original KT88 power tubes.

I sheepeshly ask her, how much do you want for those? When she said, "Oh you can just have those for free" I realy pooped myself but needless to say I removed them quickly from the premises before she changed her mind...

They were great sounding amps; nice Iron...

TT
What a great story and find. Thanks!
Drumslinger
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by Drumslinger »

+1 on that BobW. I've been pondering the idea on building a nice tube stereo amp.

You so lucked out on that tictac!! :D
tictac
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by tictac »

Sorry again but I can't resist telling the contunuing saga...

I wanted to fund a rebuild of the MK3's for HiFi use so I sold the quad of Genelex KT88's on Ebay.

I still can't believe I got 750.00 for 4 used tubes... :o
BobW
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by BobW »

V1 is a 12AT7, and V2 is a 12AU7 and am almost finished tweaking this thing. It is a clean machine w/ overdrive starting at about 12 o clock (chicken head knob reference). Still bringing in the midrange sweep on the pot (not much at all). The Treble and Bass sweep is good.
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jon
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by jon »

IF you were to change the PI to a Poseidon cascading LTP and add a Sunn 200s preamp you would have a baby WInterland.
BobW
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by BobW »

I know about the 200s, what is a Poseidon cascading LTP?
talbany
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by talbany »

BobW wrote:I know about the 200s, what is a Poseidon cascading LTP?
It's a long tail cascading differential amp just turned upside down.. :lol:

Sorry couldn't resist..Looks Cool Bob congrats..8)

Tony
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Structo
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by Structo »

Hey Bob, did you know that Dave West basically used the Dynaco MK III for the basis of his guitar amps?

Mark Farner and Grand Funk Railroad used West amps.
Tom

Don't let that smoke out!
talbany
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by talbany »

Mark Farner and Grand Funk Railroad used West amps.
And recently a VVT.. :D

Tony
BobW
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Re: Dynaco Mark III / #124 inspired preamp layout

Post by BobW »

Tom, I didn't know that (David?) West built them based on the Mk III. I thought his Fillmore Amps were similar to a Marshall. I almost bought a West amp back in the early 70s, but still have a Messenger guitar. Here's a few pics from another site, but mine is the same colr but a stereo model (w/o the built in fuzz).

LOL, thanks Tony. 8)
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