Friedman Dirty Shirley thoughts.

Marshall Amp Discussion

Moderators: pompeiisneaks, Structo, mhuss, HeeBGB

Mark
Posts: 1884
Joined: Sat Jan 15, 2005 8:10 am
Location: Sydney Australia

Re: Friedman Dirty Shirley thoughts.

Post by Mark » Thu Sep 28, 2017 11:18 pm

Did you see the TMB 18 watter built by Richie Hall?

http://www.ceriatone.com/ceriatone/wp-c ... iatone.jpg

There were a few issues with these amps, it was to do with overdriving the output stage as far as I can remember. I think this would be an issue putting the 2204 circuit onto the EL-84's, I think the issue is the 84's have more gain than 34's as well as the grid bias voltage which is around 13 volts as opposed to 30 to 40 volts in 34's. Of course I'm sure this is common knowledge and you know this.
Yours Sincerely

Mark Abbott

burger
Posts: 2
Joined: Wed Oct 18, 2017 2:06 am

Re: Friedman Dirty Shirley thoughts.

Post by burger » Wed Oct 18, 2017 2:16 am

sonicmojo wrote:
Wed Sep 27, 2017 7:35 am
I can be too curious sometimes. Here are some voltages readings from a DS Mini. Sizable PT on this.

Wall Voltage 119.1-119.6 (was creeping up during measurements)
Heaters - about 6.25 VAC
Gain switch on highest setting

V1
1 - 154.6
3 - 1.44
6 - 202.4
8 - 1.736

V2
1 - 168.1
3 - .879
6 - 274.2
7 - 168.2
8 - 169.2

V3
1 - 204.2
2 - 36.1
3 - 52.84
6 - 192.4
7 - 34.43
8 - 52.90

V4
3 - 11.39
7 - 353.1
9 - 346.9

V5
3 - 11.40
7 - 353.5
9 - 347.3
Anyone got equivalent readings for a DS 40?

Or can anyone confirm the output on the PT, is it 345V CT?

burger
Posts: 2
Joined: Wed Oct 18, 2017 2:06 am

Re: Friedman Dirty Shirley thoughts.

Post by burger » Fri Dec 22, 2017 1:20 am

Recently finished my own build of the DS40 based on the Pety the Pitbull's preamp schematic along with info gathered across the Net re the exact JTM45 power amp setup. Cracking amp, really happy with it.

User avatar
Darkbluemurder
Posts: 584
Joined: Tue Jan 03, 2006 7:28 pm

Re: Friedman Dirty Shirley thoughts.

Post by Darkbluemurder » Thu Jan 11, 2018 12:28 pm

I also have converted one of my amps to that circuit. I have 5k6 as default cathode resistor on the second stage and add another 5k6 plus a .47uf cap for a gain boost. I also upped the cathode bypass cap on the first gain stage to get fuller clean tones at low gain settings. And my mid control is a 100k audio instead of a 25k linear. Power amp is 2 cathode biased 5881s.
Great amp, does everything from cleanish to raging crunch.

Cheers Stephan

User avatar
M Fowler
Posts: 12946
Joined: Wed Jan 16, 2008 2:19 am
Location: Moorhead MN

Re: Friedman Dirty Shirley thoughts.

Post by M Fowler » Thu Jan 11, 2018 12:49 pm

Well I have built an 18w JCM800 with EL84's and the only thing I had to do was increase the voltage to get it to sound great.

I started with a Matchless Lightning home build I didn't like and converted it to JCM800 so it did have choke and tube rectifier.

I used Weber chassis with Mojotone faceplate

The tube rectifier was converted to diodes with plug in converter rather then take out the rectifier tube socket.

Mark
JCM800 18w gut 2.jpg
JCM800 18w front.jpg
You do not have the required permissions to view the files attached to this post.

Guy77
Posts: 175
Joined: Sat May 31, 2014 2:46 am
Location: Toronto, Canada

Re: Friedman Dirty Shirley thoughts.

Post by Guy77 » Thu Jan 11, 2018 2:22 pm

Looks really nice Mark! Ever since I built my rocket amp , el84s are my favourite tube! I will have to compare this JC800 preamp to the rocket preamp to see how similar they are. Sound clips if you get a chance!

Cheers

Guy

User avatar
M Fowler
Posts: 12946
Joined: Wed Jan 16, 2008 2:19 am
Location: Moorhead MN

Re: Friedman Dirty Shirley thoughts.

Post by M Fowler » Thu Jan 11, 2018 4:58 pm

Thanks,

Mounted the chassis into an 18w Marshall small box 1-12" combo cab and sold it last summer. So not available to me.

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests