mesa boogie 20/20 schem

JC@ · 01-31-2008, 09:38 PM

I would need a schematic for this amp. It is the newer all black model, don't now if that matters.
The amp works ok I believe, but I would like to have a look at the bias circuit.

Anybody please?
Thank you

JC@ · 02-01-2008, 02:40 PM

No one please?
With so many tube brands and characteristics, pretending that just plug and play a new set of tubes will be ok doesn't work for me. Too many amps come in with 'charred' glass or sounding horrible because of the nonadjustable preset bias.
I have looked hard in the web for the 20/20 schem with no success.

Chuck H · 02-01-2008, 06:04 PM

I know you probably want it instantly...Like me. But if the amp is out of warranty Mesa Boogie may send you one. Since the amp is still in production it's a "maybe". But they are generally very helpful if you call.

Chuck

JC@ · 02-01-2008, 08:12 PM

Instantly?
The owner has a venue tomorrow and another one on Sunday!

Chuck H · 02-01-2008, 10:10 PM

Well since this is Friday you may reach someone at Mesa today. Otherwise it's your a$$.

Call and see if they can Email or fax it. At the very least they can tell you the R#s to target in the bias circuit.

Your sure to get nothing if you don't ask.

Mesa Boogie: (707) 778-6565

Chuck

Gregg · 02-01-2008, 10:35 PM

http://www.bnv-gz.de/~ooehmann/schematics/mb/20_20.zip

JC@ · 02-01-2008, 10:48 PM

got it got it got it!!!
Thank you

JC@ · 02-02-2008, 06:18 PM

Current draw of the whole circuit is so important in this amp with it's design and little transformers that I soon relized that it would be better to choose the tubes from the 50 box I just received and that was a good decision as at the first attempt I could nail 21mA per tube quite easily and mantain the HT in the plates at 293 volts.
I was lucky I must admit it.
The amp was playing clean and with great dinamics.
Gregg, thanks again, the schematic was very helpful.

vintagekiki · 02-02-2008, 11:06 PM

http://www.about-guitar-amps.com/gui...s/marshall.htm
Registracija je besplatna.
http://www.about-guitar-amps.com/gui..._BackBoard.pdf
http://www.about-guitar-amps.com/gui..._BackBoard.pdf
http://www.about-guitar-amps.com/gui..._BackBoard.pdf
http://www.about-guitar-amps.com/gui...FrontBoard.pdf
http://www.about-guitar-amps.com/gui...ValveBoard.pdf

01-31-2008, 09:38 PM	#1
JC@ Senior Member Join Date: May 2006 Posts: 359	mesa boogie 20/20 schem I would need a schematic for this amp. It is the newer all black model, don't now if that matters. The amp works ok I believe, but I would like to have a look at the bias circuit. Anybody please? Thank you

02-01-2008, 10:10 PM	#5
Chuck H Senior Member Join Date: May 2007 Location: pacific north west Posts: 1,224	Well since this is Friday you may reach someone at Mesa today. Otherwise it's your a$$. Call and see if they can Email or fax it. At the very least they can tell you the R#s to target in the bias circuit. Your sure to get nothing if you don't ask. Mesa Boogie: (707) 778-6565 Chuck Last edited by Chuck H; 02-02-2008 at 12:36 AM.

02-02-2008, 11:06 PM	#9
vintagekiki Member Join Date: Jul 2006 Posts: 65	mesa boogie 20/20 schem http://www.about-guitar-amps.com/gui...s/marshall.htm Registracija je besplatna. http://www.about-guitar-amps.com/gui..._BackBoard.pdf http://www.about-guitar-amps.com/gui..._BackBoard.pdf http://www.about-guitar-amps.com/gui..._BackBoard.pdf http://www.about-guitar-amps.com/gui...FrontBoard.pdf http://www.about-guitar-amps.com/gui...ValveBoard.pdf

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02-01-2008, 02:40 PM	#2
JC@ Senior Member Join Date: May 2006 Posts: 359	No one please? With so many tube brands and characteristics, pretending that just plug and play a new set of tubes will be ok doesn't work for me. Too many amps come in with 'charred' glass or sounding horrible because of the nonadjustable preset bias. I have looked hard in the web for the 20/20 schem with no success.

02-01-2008, 06:04 PM	#3
Chuck H Senior Member Join Date: May 2007 Location: pacific north west Posts: 1,224	I know you probably want it instantly...Like me. But if the amp is out of warranty Mesa Boogie may send you one. Since the amp is still in production it's a "maybe". But they are generally very helpful if you call. Chuck

02-01-2008, 08:12 PM	#4
JC@ Senior Member Join Date: May 2006 Posts: 359	Instantly? The owner has a venue tomorrow and another one on Sunday!

02-01-2008, 10:35 PM	#6
Gregg Senior Member Join Date: May 2006 Posts: 206	http://www.bnv-gz.de/~ooehmann/schematics/mb/20_20.zip

02-01-2008, 10:48 PM	#7
JC@ Senior Member Join Date: May 2006 Posts: 359	got it got it got it!!! Thank you

02-02-2008, 06:18 PM	#8
JC@ Senior Member Join Date: May 2006 Posts: 359	Current draw of the whole circuit is so important in this amp with it's design and little transformers that I soon relized that it would be better to choose the tubes from the 50 box I just received and that was a good decision as at the first attempt I could nail 21mA per tube quite easily and mantain the HT in the plates at 293 volts. I was lucky I must admit it. The amp was playing clean and with great dinamics. Gregg, thanks again, the schematic was very helpful.

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