Search found 586 matches

by Darkbluemurder
Wed Jan 31, 2018 12:38 pm
Forum: Dumble Discussion
Topic: Why not switch OD & PAB at once?
Replies: 16
Views: 1883

Re: Why not switch OD & PAB at once?

That's great to see posts summarizing Dumble amp features - for us, newcomers - as a side note 8) My question departs much from the original but my readings make me think (maybe I'm wrong) that the PAB is (somewhat) useless without the OD engaged (& vice-versa) - hence my question. If I ever build ...
by Darkbluemurder
Fri Jan 12, 2018 2:41 pm
Forum: Technical Discussion
Topic: OD tone stack alternatives?
Replies: 12
Views: 1593

Re: OD tone stack alternatives?

Just replace the 25k mid pot in the original tone stack with something larger, e.g. 100k audio. Up to about 10 o'clock similar to stock, from there on you will get a substantial midboost (really less mid cut).

Cheers Stephan
by Darkbluemurder
Thu Jan 11, 2018 12:28 pm
Forum: Marshall Discussion
Topic: Friedman Dirty Shirley thoughts.
Replies: 62
Views: 28870

Re: Friedman Dirty Shirley thoughts.

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 ...
by Darkbluemurder
Thu Jan 11, 2018 12:21 pm
Forum: Dumble Discussion
Topic: Why Dumble cleans?
Replies: 26
Views: 5125

Re: Why Dumble cleans?

I am probably in the minority but having tested a few different D-style circuits I clearly prefer AB763 circuits for clean tones.
by Darkbluemurder
Mon Dec 18, 2017 3:48 pm
Forum: Technical Discussion
Topic: Mesa Boogie Mark III - How to get more touch response?
Replies: 15
Views: 7539

Re: Mesa Boogie Mark III - How to get more touch response?

Meanwhile I cracked the Mark III open to compare to the schematic on schematicheaven. My amp is a Purple Stripe 60 Watt model with reverb but w/o the graphic EQ. There are some differences to the lead circuit: - the resistor between the lead drive pot wiper and ground is 330k, not 150k as in the sch...
by Darkbluemurder
Tue Dec 05, 2017 4:09 pm
Forum: Technical Discussion
Topic: Holland Amp
Replies: 38
Views: 5606

Re: Holland Amp

This amp looks a lot like the Holland Brentwood I once had - reverb unit into Plexi circuit. That was a nice sounding amp.
I found the sweep control rather useless and converted it to a PPIMV.

Cheers Stephan
by Darkbluemurder
Tue Dec 05, 2017 4:02 pm
Forum: Technical Discussion
Topic: Mesa Boogie Mark III - How to get more touch response?
Replies: 15
Views: 7539

Re: Mesa Boogie Mark III - How to get more touch response?

I know this is an old thread but I finally got around to progress. I did not yet attack the Mark III but I implemented the Mark lead circuit in another amp and then started to mod it until I got what I liked. What I came up with was the following seemingly minor changes to the basic circuit (BTW if ...
by Darkbluemurder
Thu Nov 06, 2014 8:58 am
Forum: Vox/Hiwatt Discussion
Topic: Vox/Matchless Cut control
Replies: 21
Views: 9692

Re: Vox/Matchless Cut control

I have had good results with either 250k or 500k audio pots.

Cheers Stephan
by Darkbluemurder
Thu Nov 06, 2014 8:56 am
Forum: Technical Discussion
Topic: Monkeymatic Penta (Matchless Clubman inspired)
Replies: 115
Views: 22746

Re: Clubman build

@SilverFox: I'm not sold on this design. My original goal was to experiment with EF86 pentode in the preamp (but not in V1) to learn what color it could give to the circuit. Instead, as I found with this amp, it does not distort at all, but pushes the PI into clipping very easily. It's a good sound...
by Darkbluemurder
Fri Oct 31, 2014 5:16 pm
Forum: Marshall Discussion
Topic: Budda SD30 to Naylor SD60 preamp?
Replies: 14
Views: 5063

Re: Budda SD30 to Naylor SD60 preamp?

The Minimalist HRM is great. I have it in my rebuilt JMP 1959 SLP. Does everything from slight crunch to high gain with a twist of the gain knob.

Cheers Stephan
by Darkbluemurder
Wed Oct 29, 2014 1:15 pm
Forum: Trainwreck Discussion
Topic: Z-Wreck compatible DIY hobby build
Replies: 13
Views: 2706

Re: Z-Wreck compatible DIY hobby build

Beautiful amp!

Cheers Stephan
by Darkbluemurder
Wed Oct 22, 2014 11:27 am
Forum: Technical Discussion
Topic: Monkeymatic Penta (Matchless Clubman inspired)
Replies: 115
Views: 22746

Re: Clubman build

But the PI values in that amp are lifted straight from a Vox AC30. to put it in relative terms, a power amp plate supply of 300V with an 8v bias voltage. That's a third (or a fourth) of what you're contending with in this output stage. Exactly. That's why I suggested to lower the PI tail resistor. ...
by Darkbluemurder
Fri Oct 17, 2014 2:56 pm
Forum: Technical Discussion
Topic: Monkeymatic Penta (Matchless Clubman inspired)
Replies: 115
Views: 22746

Re: Clubman build

All good points. Those 270R cathode resistors on the power tubes are definitely too small. I use 390R on each power tube in my Chieftain build with 410V on the plates and 27V on the cathodes. That puts them close to but under 100% plate dissipation. If you want to increase the headroom of the PI, lo...
by Darkbluemurder
Fri Jun 13, 2014 12:01 pm
Forum: Technical Discussion
Topic: Monza master volume mod
Replies: 9
Views: 1812

Re: Monza master volume mod

My favorite PPIMV is the LarMar. To me it has 3 advantages over the cross line master as used by Matchless, Bad Cat et al - it works better at lower volumes - makes the entire amp sound better - does not affect the cut control (or in the Monza the tone control which is really a cut control with a la...
by Darkbluemurder
Fri Jun 13, 2014 11:59 am
Forum: Technical Discussion
Topic: Monza master volume mod
Replies: 9
Views: 1812

Re: Monza master volume mod

ampfab wrote:do you have a schematic?
I'm not having any luck.
I don't have a schematic for that amp but there is one out for the Mazerati GT. Same amp minus 2 output tubes plus the third control (which is a variable load on the grid load resistor before the PI.

Cheers Stephan