Quote:
Originally Posted by ojaverde
I lifted the tone stack on the normal channel of my 64 Non Reverb Deluxe. I use an A-B pedal to switch between the channels. The normal channel now is as loud on three as the trem channel on six. It's not exactly a tweed deluxe sound but it seems to have a lot more gain and is cetainly tweedier. It works as a great boost switch.
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Lifting the tonestack leaves you with one triode cascaded into another. Very raw, gainy, and in some sense I guess "tweedy."
Quote:
Originally Posted by DMace
I think it sounds better until you get the reverb channel cranked loud enough to get past the bright cap. Then, they're the same, far as I can tell.
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At that point your ears are naturally compressing the sound so your brain doesn't crack :)
The bright cap is pretty much bypassed 3/4++ up the dial, but the gain on a BF reverb channel is one triode hotter, regardless. Its got more gain, tube compression, and overdrive than a Normal channel... its going through half a preamp tube more (regardless of reverb settings). Its the nature of BF circuits. Its also the magic of the Reverb channel - not the verb, but the extra tube sauce.
Quote:
Originally Posted by 6x47
YES!
The conversion is shown on page 151 of The Tube Amp Book by Pittman. He spends about 2 1/4 pages on "Super Deluxe: Tweed-Style Preamp mod" starting with a Silverface Deluxe Normal Channel. No problem applying this mod to a blackface. It requires parts swapping, rewiring and adding a 8 or 10 uF electrolytic where the .1 cap goes on V1 on a ab763 circuit, but if you have the book it's easy.
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Gutting the plate fed tonestack and straight up cascading it will give you a very hot preamp, but there is so much more to a tweed Deluxe than a hot front end. 5E3 tweed Deluxes have a primitive phase inverter (that acts like a preamp tube in its gain, compression, and overdrive feel - compared to long tailed pair PI's), as well as a cathode power section (with plenty of sag from an innefficient power supply), and coupling caps that make it thicker than a lard milkshake... combined with NO negative feedback, a lose power section (saggy current from the 5Y3 rectifier, small filter caps, no choke, and cathode biasing on the 6V6's).
The PI and power section of the BF or SF simply do not respond dynamically in the same way a tweed Deluxe does.
A SF or BF's Normal channel is simple - input jack feeds grid, that triode's output (the grid's coresponding plate) feeds a tonestack (plate fed tonestack, instead of a the tweed Bassman or Marshall's cathode follower tonestack), which in turn feeds straight into the PI. The Reverb channel on the other hand goes grid, to plate-fed tonestack, to reverb recovery (the reverb circuit itself splits into a paralleled 12AT7 with a "mix" pot and mixing resistor to take it to the recovery circuit), to PI - which means more tube tastiness/overdrive (an extra 12AX7 triode of gain).
You can do what you like with that Normal channel's two simple triodes, but you just can't get a real authentic tweed Deluxe sound out of it - there's much more required to get that 5E3 sound.