I really wish we could revive this thread. This is a fabulous amp project and I missed out on the first group buy for boards. If anyone ever gets around to making some more PCB's for this amp I want in.
Cheff is in a class by himself with his imagination and skill set.
Please someone step up to the plate and get this going again.
Tad
Cheff is in a class by himself with his imagination and skill set.
Please someone step up to the plate and get this going again.
Tad
Same goes for me. While on the subject, does anyone have an extra set of those UGS preamplifier PCBs ?
Hi,
I had the same problem - wanted to build an UGS Preamp when there wasn't any group-buy for the boards. Here is one solution - although not the cheapest one.
The UGS All Inklusive PreAmp and UP PCBs for our french colleagues were made by PRINTED s.r.o. in Europe.
I asked the company for a price to produce a single set of UGS boards.
They already had the mask-files, drill-files, etc......
Price was: 164€ (215 US$) plus tax and 35€ shipping.
Boards were nice quality (35um copper, galvanic gold plating, green solder masks, silkscreen printing, dividing by shearing/cutting).
It is of course not cheap to produce only 1 single set.....
But if you need only one UGS or UP PCB set and there isn't any group buy.....
UP Amp PCB
UGS Preamp PCB
Hi,
I am new to amplifier building, but here is what I found on the french forum and in Nelson's docs in respect to your questions.
Should be ok.
The output stage has some similarity with the Burning Amplifier BA-2.
I recommend you to read the BA-2 manual on Pass Diy webpage.
Nelson Pass describes there the options to have 2,3,4 or 6 output devices
and needed bias adjustements.
This gives you +/- 24 Volt DC and about 42 Volt peak between the two speaker poles.
The 30Volts for the Frontend is generated by a voltage doubler circuit on the UP boards from the 24V DC. See Power-supply schematic of UP-amp.
RFB=392K/RIN=27K/ROUT=1K -> 22.1dB
RFB=392K/RIN=27K/ROUT=10K -> 23.1dB
RFB=392K/RIN=22K/ROUT=1K -> 23.7dB
RFB=392K/RIN=22K/ROUT=10K -> 24.8dB
RFB=499K/RIN=27K/ROUT=1K -> 23.9dB
RFB=499K/RIN=27K/ROUT=10K -> 25.1dB
RFB=499K/RIN=22K/ROUT=1K -> 25.5dB
RFB=499K/RIN=22K/ROUT=10K -> 26.9dB
I am new to amplifier building, but here is what I found on the french forum and in Nelson's docs in respect to your questions.
Should be ok.
The output stage has some similarity with the Burning Amplifier BA-2.
I recommend you to read the BA-2 manual on Pass Diy webpage.
Nelson Pass describes there the options to have 2,3,4 or 6 output devices
and needed bias adjustements.
You will need only one torroid per channel: 2x 18Volt AC, 400VA.
This gives you +/- 24 Volt DC and about 42 Volt peak between the two speaker poles.
The 30Volts for the Frontend is generated by a voltage doubler circuit on the UP boards from the 24V DC. See Power-supply schematic of UP-amp.
Default setup is 23dB. You can change the gain by adjusting some resistors.
RFB=392K/RIN=27K/ROUT=1K -> 22.1dB
RFB=392K/RIN=27K/ROUT=10K -> 23.1dB
RFB=392K/RIN=22K/ROUT=1K -> 23.7dB
RFB=392K/RIN=22K/ROUT=10K -> 24.8dB
RFB=499K/RIN=27K/ROUT=1K -> 23.9dB
RFB=499K/RIN=27K/ROUT=10K -> 25.1dB
RFB=499K/RIN=22K/ROUT=1K -> 25.5dB
RFB=499K/RIN=22K/ROUT=10K -> 26.9dB
442R metalfilm 1% Resistors are available e.g. from Farnell or Digikey.
Or you you could put a 432 in series with a 10 ohm resistor.
In the end 432 and 442 is only a difference of about ~2% - not too much difference anyway, but I guess you will have higher minimum bias setting.
About the bias trim pot:
Here are constructions notes for the UP Amp.
UP Amp construction notes (french)
Unfortunately it's in french, but google translate helps - sometimes.
"Les ajustables de 100Ω sont à régler de manière à obtenir la résistance
maximale lorsqu’ils sont soudés.
Ce réglage à la résistance maximale permettra de démarrer avec le courant
de repos le plus faible possible, ça évitera sûrement de la fumée
"translates to
"The adjustable 100Ω should be paid to obtain the resistance maximum when they are welded.
This adjustment to the maximum resistance will start with the quiescent current as low as possible, it surely will avoid the smoke
"Hope it helps......I am an absolute beginner in electronics.
442R metalfilm 1% Resistors are available e.g. from Farnell or Digikey.
Or you you could put a 432 in series with a 10 ohm resistor.
In the end 432 and 442 is only a difference of about ~2% - not too much difference anyway, but I guess you will have higher minimum bias setting.
About the bias trim pot:
Here are constructions notes for the UP Amp.
UP Amp construction notes (french)
Unfortunately it's in french, but google translate helps - sometimes.
"Les ajustables de 100Ω sont à régler de manière à obtenir la résistance
maximale lorsqu’ils sont soudés.
Ce réglage à la résistance maximale permettra de démarrer avec le courant
de repos le plus faible possible, ça évitera sûrement de la fumée
translates to
"The adjustable 100Ω should be paid to obtain the resistance maximum when they are welded.
This adjustment to the maximum resistance will start with the quiescent current as low as possible, it surely will avoid the smoke
Hope it helps......I am an absolute beginner in electronics.
OK thank, I am also practically beginner