86ing it: Ef'ing up my amp

[Reeltarded]

I am making a parts list to rebuild a JTM 45 Tremolo into a straight JMP 50 with a switchable Ef86 stage in the middle of V2 at the entry of the CF.

The Ef gets it's own drive control, and something of a tone shaper, like the 6-pos control in the brown note layout of the foxy 18. On paper, it seems simple enough to get it as a para/ser on a switch so I can

1. Bypass
2. Cascade
3. Direct to the Ef on it's own input.

My question is about the part when I get it all wired up, and find the gain staging totally underthought, underplanned, and completely misengineered. Is ramming 3 12ax7 triodes down this things throat total overkill? Maybe it should come before V2a, and the switching should include a cold bias for V2a when the 86 is inserted in cascade?

Ideas? Thoughts? I've drawn it out 100 times. Time to make it hurt if I drop it on my toe. Ouch!

[chief mushroom cloud]

look at a Selmer Zodiac schematic.......12ax driving a EF86

[rsalinger]

I am making a parts list to rebuild a JTM 45 Tremolo into a straight JMP 50 with a switchable Ef86 stage in the middle of V2 at the entry of the CF.

The Ef gets it's own drive control, and something of a tone shaper, like the 6-pos control in the brown note layout of the foxy 18. On paper, it seems simple enough to get it as a para/ser on a switch so I can

1. Bypass
2. Cascade
3. Direct to the Ef on it's own input.

My question is about the part when I get it all wired up, and find the gain staging totally underthought, underplanned, and completely misengineered. Is ramming 3 12ax7 triodes down this things throat total overkill? Maybe it should come before V2a, and the switching should include a cold bias for V2a when the 86 is inserted in cascade?

Ideas? Thoughts? I've drawn it out 100 times. Time to make it hurt if I drop it on my toe. Ouch!

I think that Dr. Z got the tone control "right" on the Stangray... Instead of the standard-issue 6-position rotary knob, he went the route of a Baxendall-type eq.

[Darkbluemurder]

I am making a parts list to rebuild a JTM 45 Tremolo into a straight JMP 50 with a switchable Ef86 stage in the middle of V2 at the entry of the CF.

The Ef gets it's own drive control, and something of a tone shaper, like the 6-pos control in the brown note layout of the foxy 18. On paper, it seems simple enough to get it as a para/ser on a switch so I can

1. Bypass
2. Cascade
3. Direct to the Ef on it's own input.

My question is about the part when I get it all wired up, and find the gain staging totally underthought, underplanned, and completely misengineered. Is ramming 3 12ax7 triodes down this things throat total overkill? Maybe it should come before V2a, and the switching should include a cold bias for V2a when the 86 is inserted in cascade?

Ideas? Thoughts? I've drawn it out 100 times. Time to make it hurt if I drop it on my toe. Ouch!

I think that Dr. Z got the tone control "right" on the Stangray... Instead of the standard-issue 6-position rotary knob, he went the route of a Baxendall-type eq.

The Baxandall type tone controls are used on the Route 66, KT-45 and Delta 88. The Stangray has only one tone control which is similar to that of the Ghia.

[10thTx]

Ideas? Thoughts?

I have used this type of 5879 OD with success. Maybe you can find some ideas to consider with this schematic? The left over triode could be used to have a paralleled V1 ........... OR add a 12A_7 triode as a cathode follower to the 5879.

The quasi-sorta 5E3 tone stack works after the 5879.

You might find some other ideas to consider here:
http://www.el34world.com/Forum/index.ph ... 6.msg99077

With respect, 10thtx

[surfsup]

Is that lead between the 56k/220k on the 5879 plate supposed to be there?

[Reeltarded]

I don't want a full TS for it, but something on a single control. I think I just found a use for a second presonance type control that is scaled a bit differently.

This is going to be a headache. I'm gonna need that pesky math, darn. More discovery. Wooooo!

[10thTx]

Is that lead between the 56k/220k on the 5879 plate supposed to be there?

corrected! thanks, 10thtx

[tubeswell]

I've used a Big Muff style TS after EF86 and it smokes. Use 1M resistors and pots to keep the output-input impedance bridging optimised.

[ChopSauce]

I've used a Big Muff style TS after EF86 and it smokes. Use 1M resistors and pots to keep the output-input impedance bridging optimised.

(Not so) sorry for hijacking(*) this pretty old thread, but:

- could you explain me what you mean exactly by "optimised", please?

I could read that your variation of the Big Muff tone stack was scaled for a tube amp but the (1:1) ratio between the pot and the resistor values does not match that (3:1) of the Big Muff pedal...

Thousand thanks for the suggestion, by the way...
___

(*) I'm not sure what that means but I've read that several times before ...