Matt Scoffields sound/tone.

[Structo]

Tom,

You can easily source .039 caps. Use that on the switch!

Fat is .01 not .05 IMO. Do you find the larger midcap tone fatter??

Hmmm, I thought it was, the switch is on the back so I usually reach around and flip it to what sounds better.
I'll have to take a look at it again and see what I have there.

Pretty sure I did use a .05 and .01

[Dr d]

Hey Tom, tried your suggestion (switchable mid cap) and it works great, thank you. 0.01 is definately the FAT mode! Considering a slope switch and also an OD entrance switch (0.05cap/10meg to ground) to see the effect on my OD. Thanks again for your suggestion. Doc.

[FUCHSAUDIO]

Matt's taken a break from D-style amps, as he "grew tired of the Robben comparisons) from his manager btw.

[Structo]

Dr. D,
I was in my amp today and Scott is right.
It is fatter when just the .01 is in circuit.
I wonder why that is?

When I simulated a larger mid cap in the Duncan Tone Stack Calculator, when I increased the mid cap value it raised the low mids higher.

I have it labeled correctly on my back panel but the amp is up against a
wall so I usually just reach behind and flip it either way and leave it on the one that sounds best to me.

I know the Dumble stack is a bit different from the Fender stack but I thought that was kind of weird.

Can anybody explain that?

The OD entrance mod is good as well. It thins the OD a bit and brings more clarity to it.

The other thing to do is change the CL2 coupler to .02uF

Then when in Overdrive the .05 and .02 are in series for a total of .014.
Seemed to help with the articulation.

So just take the .05 from the CL2 spot and use it on the OD entrance then put a .02 on CL2.

Another worthy mod Dr. D is to put a switch on the local feedback loop on V1.
I have the switch labeled Raw and Smooth.
Raw is with the loop off. (I hope I got that one right )

You can see it on my Tweaked layout.

Are you running 6L6's?

If so then if you were to do everything on the Tweaked layout I think you would like the results.

Today I changed the 180K on OD2 to a 120K and also the slope to 120K.

Over all the single best tweak you can do is get the voltages to the recommended amounts as it really does shape the tone in the right direction.
V1 190-200
V2 200-210
V3 285-290

[FUCHSAUDIO]

Another worthy mod Dr. D is to put a switch on the local feedback loop on V1.
I have the switch labeled Raw and Smooth.
Raw is with the loop off. (I hope I got that one right )

You can see it on the Tweaked layout.

I use a three position, and do 22 meg 44 meg and open circuit on a few of my own amps. It's nice to have more compression, less compression, and NO compression on the toggle.

[Dr d]

Thanks for all of the suggestions guys..... thought this thread had run its course!!!! Keep the suggestions coming. I am really struck by the versatility of this amp....such subtle changes seem to make an enormous impact on the sound. Yes Tom, i'm running a pair of old GE 6l6s on CATHODE BIAS. The biasing sounds lovely in this 50w format and drops the volume a little bit. Mr FUCHSAUDIO ( sorry, I dont know your first name!) I have done as suggested with the LNF switch in the past and liked it much.....something I think I shall revisit!!! I am collecting alot of switches!! Anyway thanks again. Cheers, Doc.

[Structo]

You're welcome Doc.

Mr. Fuchs sometimes goes by Andy.

Are you a medical doctor?

Dumble cathode biased, eh?

Not sure anybody has done that here.

I do enjoy a nice pair of 6V6 cathode biased in my latest Rocket impersonation.

[FUCHSAUDIO]

Thanks for the nod....lol.

My "practice rat" is a 20-W ODS with 2 6V6's and a Mercury output for a Blackface Deluxe. I have two magic switches: Fixed and cathode bias and triode/pentode. It's a great little screaming pig of an amp....nice for recording, rehearsals, maybe a smallish gig....worth playing with. I love lots of watts, give me 100 or 150 and i am happy, but for just greasy dirty blues and rock grind, this puppy rocks !!!

[talbany]

Thanks for all of the suggestions guys..... thought this thread had run its course!!!! Keep the suggestions coming. I am really struck by the versatility of this amp....such subtle changes seem to make an enormous impact on the sound. Yes Tom, i'm running a pair of old GE 6l6s on CATHODE BIAS. The biasing sounds lovely in this 50w format and drops the volume a little bit. Mr FUCHSAUDIO ( sorry, I dont know your first name!) I have done as suggested with the LNF switch in the past and liked it much.....something I think I shall revisit!!! I am collecting alot of switches!! Anyway thanks again. Cheers, Doc.

+1 on the cathode bias.. Cool things I notice about is
Bigger fuller more low end bloom at lower volumes..
The transition into grind is smoother
Some nice compression as you push them
Depending on how you bias them up hot you can get some nice sustain and a little more responsive all be it a bit slower reacting..
They lack in
Punch/ headroom (less efficient)
Can make the OD side a bit soft especially with the low plates

If you like the attributes and feel of the cathode biasing but want more headroom try a pair of 6550's or my fave big bottle KT-88's like the Gold Lions if you can afford them.. A pair of these is all you need to do club gigs with and still walk the clean breakup line nicely..
Mine is a high plate Non HRM with Traynor YBA1A Hammond Transformers(Monsters).. Loaded 2 JJ-KT88 w Fixed bias cathode bias switch though it pretty much stays in Cathode.. BTW 2 KT-88's 500v will give you between 60-65 watts clean OPT.. Very cool!!..Surprised nobody does the switch more..

Tony

[Dr d]

Hey Tony, great to hear from you again. I've got to admit to approaching the D-style from a 5E3 kind of angle. What has always drawn me to these (D-style)amps is the OD tone. I'm never too worried about too much clean headroom......the high plate pre-amp is more than enough for me. This is partly why I went for cathode biasing, in the hope that the output section would start to break up a little sooner..... I dont need alot of volume either!!! Finally, I hoped to be able to run some JJ6V6s in this as well. I understand JJs can take relatively high plate voltages. Is this right? My current set-up with 440v on the 6L6 plates (two valves of course!) is 220R sharing the two cathodes bypassed with a 25UF/50v cap. Would this be too much for the JJ6L6s? Cheers, Doc.

[Dr d]

Tom, thank you also for your input. Here a great tweak passed on to me by Tony. Try raising your drive pot from 100k to 250k for a much "broader"(A little more of everything I guess) sound. A real improvement. Thanks again Tony for that one.