Univox amp

[Mats]

Hi
I talked to a friend the other day, he wants some input to start build one small amp with tremolo.
At first we talked about SE amps but then we got into PP amps and looked at one Univox U-45B (four tube amp) on the Youtube.
It was then that I looked at some information about another Univox amp, the U-75.
Looks like its a five tube amp (12AX7, 12AX7, 6AQ5, 6AQ5 and 6X4)
I cant find any more info or schematic of this amp. Some direct to U-155R, but its not the same preamp tubes.
Does anyone have a schematic of U-75 ?
/Mats

[uki]

Here is a small amp with tremolo with good information about it!

http://sluckeyamps.com/RCA/Ampeg_J12B.pdf
http://sluckeyamps.com/RCA/RCA.htm
https://www.youtube.com/watch?v=Kfqidpvr2hI

[Mats]

Hi
Thank you for your answer and information about the Ampeg Jet.


I will try to search for more info. about the U-75.
Perhaps the U-75, is like the U-45B  and that they changed 6BM8 tubes for 6AQ5, 6AQ5 and one 12AX7
/Mats

[silverfox]

One research hit indicates it's the same as this amp without the Reverb.

http://el34world.com/charts/Schematics/files/univox/Univox_U-155R_GUITAR_AMP.pdf

silverfox.

[kagliostro]

But in the 155 there is a 6AU6 as V1 .....


Franco

[silverfox]

An EF86 or 5751 may work in that position as a substitute. Matchless DC30 channel 2 input example.

silverfox.

[Ritchie200]

The U75 is certainly a mystery as it appears nobody has any schematics or has bothered to share their drawings.  Here is a gut shot with some components in view.  Might get you started...


https://reverb.com/item/2324654-univox-u-75-2x10-tube-combo-1966-black-blue-jensen-c10-s


Jim

[kagliostro]

Here is the photo of the board (is not possible to save imeges from the link)



and here of the faceplate



Seems that someone swapped some nice Paper Oil capacitors for polietilene .....



Franco

[jjasilli]

Here's a U45 I did a trem repair on, with schematic.

[2deaf]

With the tube lineup, it might be more similar to the U-255R without the reverb.  I rebuilt one that was very similar to a U-255R and Fenderized it as long as I was at it.  The only ID on the whole amp was "MUSCAL (sic) AMPLIFIER MODEL G" on the printed circuit board.  The lack of model ID's on Univox's makes me wonder how people know what model they have.

[Mats]

Hi
Thanks for your effort, in finding some information about the U-75.
/Mats

[jjasilli]

Here's the Prowess sight with more schematics.  I could not find it yesterday  (thought it was "Powers"; it's "Prowess"):  http://www.prowessamplifiers.com/schematics/univox/

[JRobin68]

Hi
I talked to a friend the other day, he wants some input to start build one small amp with tremolo.
At first we talked about SE amps but then we got into PP amps and looked at one Univox U-45B (four tube amp) on the Youtube.
It was then that I looked at some information about another Univox amp, the U-75.
Looks like its a five tube amp (12AX7, 12AX7, 6AQ5, 6AQ5 and 6X4)
I cant find any more info or schematic of this amp. Some direct to U-155R, but its not the same preamp tubes.
Does anyone have a schematic of U-75 ?
/Mats

[JRobin68]

This is the U75 schematic

[kagliostro]

Really nothing in good shape but very easily readable

Have you a way to post that schematic positioned in plan (flat) ?

THANKS

Franco

[PRR]

Have you a way to post that schematic positioned in plan (flat) ?

I think he copied it off an auction site, does not have the actual paper?

It is ugly but readable.

I did some editing but it really needs the old brown image to check small details.

[JRobin68]

It's all I have, took forever to even find that one.

[sluckey]

It's already in Hoffman's schematic library.

     https://el34world.com/charts/Schematics/files/Univox/Univox_U75.pdf

[JRobin68]

Nothing like getting a 6yr. Old thread started again, lol.

[kagliostro]

Thanks to all


Franco