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Thx, Nathan! I'm confused about #1. . . I was thinking that with B where it is currently shown it would function as you indicate, but ONLY when the Boost circuit is activated. Otherwise the signal would completely bypass the Boost stage (including the A1M pot) and enter the V1.B grid directly...

After wrestling with this and reviewing a number of schematics this is what I came up with this as a starting point. It's basically a Space Heater stuck on to the front end of a classic 5F6A schematic. I've decided to defer any issues regarding modifying the tone stack, etc. for now. My...

Just comparing tone stacks with the Duncan Tone Stack Calculator. . . '59 Bassman vs JTM45 vs Blackface AB763. I'm curious why the variance btw '59 & JTM45 as they have identical tone stack components. The '59 was "programmed" on the Fender tab and the JTM45 on the Marshall tab. Maybe there...

Question on 12AX7's. They're said to have a gain factor of 100. Is that "per side" or total of the output of both sides?

Hmmm? . . . that's a booster isn't it? A tube preamp is putting out 20+ volts isn't it? Don't you need to reduce the output of the preamp? That can be done with the Master Volume. But to broaden the useable sweep of the MV I was wondering about adding a resistor or voltage divider network in...

Nothing's popped up lately with respect to these boards. I've recently completed a couple of Sushibox builds (tube driven preamps) and am curious about the relationship btw the output of the tube preamp and the input requirements of a typical Class D amp or PA mixer. I understand both want to...

I'm running strictly as a preamp into a Class D power amp so no "over the top" behavior.

@MichaelW - You're right. Fender blackface preamps are classics. The big MID cap doesn't change that. Just gives you more MID range, but the standard Fender value is still in there. The PA isn't as aggressive as the blackface Reverb models because it lacks the extra umph the add'l preamp...

Well. . . good news and bad news. Bad news is my foot switchable RAW has been voted down :cry:. The pro player I have testing the PA is also testing the preamp I made which has the foot switched RAW. He thinks it doesn't function well as a "dual channel thing". RAW's great for making the...

A bit confused. Under standard wiring doesn't the signal comes in on P2 and out P3 to GRD, a 10K variable resistor??? My Deluxe clone is wired that way, but then P3 goes in series to a second 250K variable resistor (RAW pot) which is ADDITIVE to the Mid. The foot switch just takes the signal...

I'm implementing a foot switchable RAW feature into my second build. To clarify, I assume the pins on the PCB Mid socket correspond to the pins on the schematic to the right of the attachment. In both cases we're looking at the "underside" of the pot. Pls verify.

Oh, I can measure it. I'm just lazy and was hoping a mfg had posted a dwg just like Hammond does.

Hammond has great DWG files for their enclosures, but my Google search didn't find anything for a 125B. Anybody know a source? I could even probably do a take off from a 3D file.

Yeah, my wife wishes I had a decent tone stack (I guess you could take that a couple of ways)!?!? She accuses me of not being the brightest bulb in the box. Anyway, my next quandry. . . . I don't have any sense of how hot the signal is coming off of the tone stack in the 5F6A. The Particle...

Now comes the Bright Switch conversation. . . do we really need one? There isn't one in the London Underground or Particle Accelerator. When the Volume knob is at 10 the bright cap has no effect. It's only when you turn down the volume the high end starts to go away. Since we're dealing with...

From the discussion on cathode followers in the Particle Accelerator thread you indicated that the voltage coming out of the cathode follower is much lower than that coming off of the plate. If so what voltage cap would work in the tone stack. . . 25-50V as with "normal" cathode ground bypass...

I note that cathode follower questions really fall under discussions about the 5F6-A/JTM45. I have a follow up on tone stack caps voltages which I will bring up there. Sorry for the crossover.

What's your take on the addition of the cathode follower to the 5F6A/JTM45 circuit. Why'd they put that in?? I understand it lowers impedance (from 38K to ?), but how does that help and what other "benefits" does a CF ostensibly provide? UPDATE: Never underestimate the power of Google. My...

What would I do with a 50M pot? If its as rare (i.e. non existent) as you say and I can find one I'll sell it at Southeby's for big $!! Seriously, if you'll look at the Robinette excerpt below you'll find he's spec'ing a resistor in the range of 22M-44M to go in series with a .047u cap...

Re 1: How does the parallel wiring differ from "normal" in tone terms? Re 3: Do I also want the .022u coupling cap upstream of the 220K? Re: stouter resistor, I would want it to mirror the output characteristics of the Particle Accelerator. Does the cathode follower add any voltage that...