Friedman Dirty Shirley thoughts.

Marshall Amp Discussion

Moderators: pompeiisneaks, Colossal

frankdrebin
Posts: 131
Joined: Wed May 14, 2014 11:40 am

Re: Friedman Dirty Shirley thoughts.

Post by frankdrebin »

10k in 2nd stage,with the switch you parallel a 4,7k or 3,3k and .68uF

Inviato dal mio Redmi 4X utilizzando Tapatalk

User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Re: Friedman Dirty Shirley thoughts.

Post by sonicmojo »

Thanks! I was just playing around with a DS mini at a shop today. The 10K alone must be the middle position then, lowest overall gain structure but cold clipping.
---------
Bryan
mojotom
Posts: 237
Joined: Wed Feb 01, 2006 12:47 am

Re: Friedman Dirty Shirley thoughts.

Post by mojotom »

sonicmojo wrote: Thu Sep 21, 2017 10:31 pm Does anyone know how the three-way gain switch is implemented? I'm assuming it is probably just ground resistors to the gain pot but it's not reflected in that schematic so maybe it is just on newer versions of the amp.
From memory second tube stage cathode : 10k for clean mode, 3k3 // for the first gain mode then add a 470n for the 2nd gain mode (similar to non switch mode).
I remember aiming for 2k7 for mine to mimic the original Shirley mode.

But on the mini Shirley info I got (not sure of its accuracy) still 10k fixed but either 47k or 2k7/680n (470n cathode caps for the Shirley, 680n for the mini)
Last edited by mojotom on Sat Sep 23, 2017 12:39 am, edited 1 time in total.
Mark
Posts: 2957
Joined: Sat Jan 15, 2005 8:10 am
Location: Sydney Australia

Re: Friedman Dirty Shirley thoughts.

Post by Mark »

That's it. The switch is quite noisy as there is a significant change in DC voltage.
Yours Sincerely

Mark Abbott
User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Re: Friedman Dirty Shirley thoughts.

Post by sonicmojo »

The implementation of the voltage divider at the master volume is interesting. I think it is different values for mini versus regular but probably the same idea......probably part of the reason the first PI resistor is dropped to 470K. Trying to wrap my head around the science of what is happening there if anyone already knows. It seems to help keep the overall gain/tone steady as the volume is increased or decreased (at least on a mini).
---------
Bryan
User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Re: Friedman Dirty Shirley thoughts.

Post by sonicmojo »

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
You do not have the required permissions to view the files attached to this post.
---------
Bryan
Mark
Posts: 2957
Joined: Sat Jan 15, 2005 8:10 am
Location: Sydney Australia

Re: Friedman Dirty Shirley thoughts.

Post by Mark »

Looks good. Who's effects loop is it?
Yours Sincerely

Mark Abbott
User avatar
mhartman
Posts: 611
Joined: Sun Jun 15, 2008 5:43 pm

Re: Friedman Dirty Shirley thoughts.

Post by mhartman »

Dave makes his own loop these days.

Mark wrote: Wed Sep 27, 2017 11:40 am Looks good. Who's effects loop is it?
User avatar
xtian
Posts: 6990
Joined: Mon Apr 19, 2010 8:15 pm
Location: NorCal
Contact:

Re: Friedman Dirty Shirley thoughts.

Post by xtian »

That's very nice looking. You can easily remove and replace all the components from the top of the PCB...except the radial caps...
I build and repair tube amps. http://amps.monkeymatic.com
User avatar
alkuz1961
Posts: 179
Joined: Sat Mar 03, 2012 3:32 am
Contact:

Re: Friedman Dirty Shirley thoughts.

Post by alkuz1961 »

early version of the Dirty Shirley Mini
You do not have the required permissions to view the files attached to this post.
mojotom
Posts: 237
Joined: Wed Feb 01, 2006 12:47 am

Re: Friedman Dirty Shirley thoughts.

Post by mojotom »

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

The mini is a bit different, 680n cathode caps and a "balanced" PI (not 470k/1M).

Could you confirm if you still got the amp the value of the master pot sonicmojo ?
Should be A100k
Mark
Posts: 2957
Joined: Sat Jan 15, 2005 8:10 am
Location: Sydney Australia

Re: Friedman Dirty Shirley thoughts.

Post by Mark »

Will there be any clips forthcoming from these builds? :wink:
Yours Sincerely

Mark Abbott
User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Re: Friedman Dirty Shirley thoughts.

Post by sonicmojo »

mojotom wrote: Wed Sep 27, 2017 10:25 pm
The mini is a bit different, 680n cathode caps and a "balanced" PI (not 470k/1M).

Could you confirm if you still got the amp the value of the master pot sonicmojo ?
Should be A100k
I couldn't see the values on the alpha pots and the amp is returned. Sorry.

I was curious about how these sound and feel as I'm still experimenting with and comparing my recent 18 watt high gain Marshall style build to other amps. For what it is, the DS Mini is a well thought out and decent sounding amp. I think some values of pots, voltage dividers, etc were chosen to user proof it a bit.
---------
Bryan
Mark
Posts: 2957
Joined: Sat Jan 15, 2005 8:10 am
Location: Sydney Australia

Re: Friedman Dirty Shirley thoughts.

Post by Mark »

recent 18 watt high gain Marshall style build
What is the circuit for the high gain Marshall style amp?
Yours Sincerely

Mark Abbott
User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Re: Friedman Dirty Shirley thoughts.

Post by sonicmojo »

Mark wrote: Thu Sep 28, 2017 1:20 pm
recent 18 watt high gain Marshall style build
What is the circuit for the high gain Marshall style amp?
In the 18W amp that I recently transformed from another circuit, I started pretty close to the standard Marshall master volume scheme like this from Rob Robinette but I used a .001 first stage coupling cap so my amp is fairly bright, even without any bright cap on the first volume. In my case I had an extra triode so I paralleled the last stage before the cathode follower with a shared 50K plate resistor and two separate 1.6K/25uf cathodes. Been tweaking values and voltages a bit since but really kind of close the the traditional chain, as is the DS (for the most part). As I've been adding some of the extra voltage dividers around the volume pots, like the DS, the range of possible gain tightened up a whole lot.
You do not have the required permissions to view the files attached to this post.
---------
Bryan
Post Reply