Recent Posts

21

Tube Amp Building - Tweaks - Repairs / Layout once-over?

« Last post by johnnyreece on April 22, 2026, 02:16:51 pm »

I'm thinking of diving in to high gain territory, but I don't have much experience in that are.  Logic says to take a proven design and work straight from that.  Unfortunately, the parts I have say that's a big fat no.  I'm wanting to do a lower-power SLO with russian tubes (62NP and 6P1P).  I'm also using a chassis that's got much less room than a traditional SLO would have.  I've tried trimming what I can, and I *think* I have a reasonable start to a layout.  I've included a copy of what I have so far, as well as the schematic I cobbled together to work from (and I've highlighted what I've got on the layout).  One example of a concern are the vactrols; I've never used them before!  Stuff like that is what I'd like to sort out before I get much further on the layout.  I do plan on using shielded wire at least early on in the preamp.  Also taking any general recommendations from the high-gain folks.  I really appreciate anyone taking the time to take a look!

22

Other Topics / Re: Meme of the day

« Last post by EL34 on April 22, 2026, 02:00:29 pm »

The manslater

23

Tube Amp Building - Tweaks - Repairs / Re: A Question about system design

« Last post by pbman1953 on April 22, 2026, 10:36:22 am »

What would be the benefit of having this tone stack?

24

Other Topics / Re: Meme of the day

« Last post by shooter on April 22, 2026, 09:31:29 am »

...

25

Other Topics / Re: Dave Mason has past.

« Last post by Willabe on April 22, 2026, 08:17:43 am »

From the Traffic live album "Welcome to the Canteen."

i=DDnLPoX-3Yag2TvA

26

Other Topics / Re: Dave Mason has past.

« Last post by Willabe on April 22, 2026, 08:09:49 am »

I always liked this Traffic song.

i=jHDuB0txjXQIUxTA
And of course this;

i=_P9UEtdudkubjtMy

27

Other Topics / Dave Mason has passed.

« Last post by Willabe on April 22, 2026, 08:03:54 am »

At 79, in his home.

i=E--aa9CVQtJ47kvr

He was almost in Clapton's Derek and the Domino's band. They were playing together, there's conflicting stories about why he didn't stay. Bobby Whitlock said he thought that the 3 part harmony blend Mason, Clapton and Whitlock got was beautiful! 

Mason was hanging around and playing with Delaney & Bonnie. At that time Delaney & Bonnie had some of the best musicians playing with them. Any given night you could see on stage with them, Mason, Clapton, and George Harrison. Along with bass Carl Radle, drummers Jim Gorden & Jim Keltner, keyboards Bobbie Whitlock, sax Bobbie Keys, and trumpet Jim Price.   

Here's Delaney & Bonnie live acoustic, with Mason on a National resonator, Clapton and Whitlock.

i=5fb8uNS1WO4KLbHm

28

Tube Amp Building - Tweaks - Repairs / Re: Princeton Reverb circuit refinements

« Last post by tristanc on April 22, 2026, 06:49:30 am »

It's coming together nicely. Populated the PCB in a little over an hour. Next will be doing the flying leads from PCB -> off board components. I've mostly tightened up the chassis parts. This will likely be a "once it's in, it's in" build...

29

Tube Amp Building - Tweaks - Repairs / Re: Zener Bias "Trick" for Cathode Biased Amps

« Last post by pdf64 on April 22, 2026, 05:04:54 am »

Is that where the math for using a composite curve of 1/4 the primary and 1/2 the primary is derived from in calculating a push-pull loadline?  i.e. maps to the 1/4 Za-a until the bias point for class B, and then continues on through the 1/2 Za-a loadline for class A?  I just took it for granted that it was written and it must be so - I didn't think about the trafo turns ratio being what was dictating why we use 1/4 and 1/2 specifically.

https://www.valvewizard.co.uk/pp.html

Yes, you've got it, that's it 

30

Tube Amp Building - Tweaks - Repairs / Re: A Question about system design

« Last post by AlNewman on April 21, 2026, 07:23:12 pm »

I think it's because both the bass and mid controls are wired as variable resistors.
You could wire it like a Marshall tone stack with the wipers making voltage dividers, and it would react like a Marshall tone stack.

The cool thing about that amp is the active eq.