Monkeymatic Black Butte (univalve build)

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xtian
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Monkeymatic Black Butte (univalve build)

Post by xtian »

Building a SE amp based on THD's Univalve (schem attached). First draft layout attached.


Screen Shot 2017-11-28 at 8.53.23 PM.png
THD_UniValve_1_41_062104.pdf
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Last edited by xtian on Tue Jan 23, 2018 1:24 am, edited 1 time in total.
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galtjunk
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Re: Monkeymatic univalve build

Post by galtjunk »

Nice work.

I considered building one of these but I found I could buy one for around $400 so I bought one.
It is a great amp.

Goold luck.
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xtian
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Re: Monkeymatic univalve build

Post by xtian »

galtjunk wrote: Wed Nov 29, 2017 10:07 amI considered building one of these but I found I could buy one for around $400 so I bought one.
In know, right? I was tempted to just buy a THD. But I already have the iron and all the small parts except the large filter caps, which I ordered as radials from mouser. And I have a bunch of single, octal power tubes.

I’m building this as a “desktop” model. That is, it’s just a simple square of aluminum with a hardwood frame, like a hi-fi amp.
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M Fowler
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Re: Monkeymatic univalve build

Post by M Fowler »

I'm not familiar with this amp at all. From online sources one can use about any common power tube which is always fun.
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xtian
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Re: Monkeymatic univalve build

Post by xtian »

M Fowler wrote: Wed Nov 29, 2017 4:46 pm I'm not familiar with this amp at all. From online sources one can use about any common power tube which is always fun.
That's what THD says. But there's no provision for changing the bias. I guess they just set it conservatively and let the chips fall.

The OT I'm using is Hammond 125SE, which has a flexible set of secondaries, so that will be helpful to match the power tube to the load.
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sluckey
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Re: Monkeymatic univalve build

Post by sluckey »

Take a look at that schematic. The filament winding CT and the bridge rectifier DB2 negative terminal are both connected to ground. That will not work.
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xtian
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Re: Monkeymatic univalve build

Post by xtian »

Thank you, Steve. I think I can fix that as shown:
Untitled-1.jpg

Right?
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Re: Monkeymatic univalve build

Post by sluckey »

That'll do it. Seems like that very same issue came up about a month ago? It was either here or over at Hoffman's. Can't remember which. I usually see that a few times a year, especially when someone wants to power a relay from an existing filament circuit.
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xtian
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Re: Monkeymatic univalve build

Post by xtian »

Yes, that was me asking about it, related to my addition of digital reverb into an existing amp.
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telentubes
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Re: Monkeymatic univalve build

Post by telentubes »

The Univalve is a cool little amp. I got to spend a bunch of time with one a few years back and really liked it.
I know of one for sale if you are interested (they are not hard to find), but building is way more fun, isn't it?
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Re: Monkeymatic univalve build

Post by xtian »

Got the cabinet and top and bottom aluminum plates cut and glued, ready for gun stock oil. The side walls are 2.5", which appears to be the lower limit of usefulness for the bisquit joiner--you can see the bisquit peeking up. I just chiseled the ends down.

IMG_8790.jpg
IMG_8791.jpg
IMG_8793.jpg
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pompeiisneaks
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Re: Monkeymatic univalve build

Post by pompeiisneaks »

Very cool, are those #0 biscuits?

I just got a joiner (makita) after the peeps here have spoken so highly of them.

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xtian
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Re: Monkeymatic univalve build

Post by xtian »

pompeiisneaks wrote: Fri Dec 01, 2017 11:05 pmVery cool, are those #0 biscuits?
Ha! I don't know! I'm a bisquit n00b. Just using the bisquits that came with the unit.
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pompeiisneaks
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Re: Monkeymatic univalve build

Post by pompeiisneaks »

Oh then you may be able to get smaller ones and fit them there, there are three normal sizes, 0, 10 and 20, Yours may be 10 or 20. Your joiner 'should' allow you to adjust to the right size. You generally want to use the largest possible, as I understand it, but I just bought mine and this is from youtube vids :)

I may be out in left field :D

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Re: Monkeymatic univalve build

Post by telentubes »

Handsome little cab you whipped up there. Should be nice with the gun stock oil. I've grown to like that stuff.
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