Search found 892 matches

by Tonegeek
Mon Feb 08, 2021 12:41 pm
Forum: Fender Discussion
Topic: Crema Wheat Tonestack?
Replies: 2
Views: 1996

Re: Crema Wheat Tonestack?

Crema stack is slightly altered from stock 6G3
Normal channel has
10uf Cathode by pass cap || 1k5 resistor
680p treble cap
.02 bass cap

Bright channel has
25uf Cathode by pass cap || 1k5 resistor
500p treble cap
.01 bass cap

Tonally, the channel differences are subtle.
by Tonegeek
Mon Feb 08, 2021 11:30 am
Forum: Technical Discussion
Topic: Best way to do grid stopper on cathodyne
Replies: 8
Views: 771

Re: Best way to do grid stopper on cathodyne

I suppose I am over-thinking it. Thanks.
by Tonegeek
Sun Feb 07, 2021 8:01 pm
Forum: Technical Discussion
Topic: Best way to do grid stopper on cathodyne
Replies: 8
Views: 771

Re: Best way to do grid stopper on cathodyne

I am still a bit confused. I got on this issue after reading this : http://www.valvewizard.co.uk/cathodyne.html at the paragraph "Avoiding Unpleasant Overdrive". If I understand the trend of replies though, I should avoid putting the grid stopper before the grid leak. But, as df64 explains, what ai ...
by Tonegeek
Sun Feb 07, 2021 11:01 am
Forum: Technical Discussion
Topic: Best way to do grid stopper on cathodyne
Replies: 8
Views: 771

Re: Best way to do grid stopper on cathodyne

So should think of this as a voltage divider vs current divider? Merlin shows this mod as a voltage divider. Rob Robinette implements it as a current divider (grid stopper after the grid leak. I am leaning toward the current divider version, but do I need to be concerned at all about the effect eith...
by Tonegeek
Sat Feb 06, 2021 5:42 pm
Forum: Technical Discussion
Topic: Best way to do grid stopper on cathodyne
Replies: 8
Views: 771

Best way to do grid stopper on cathodyne

See attached. I have a cathodyne PI and have experimented with limiting drive by using Merlin's (Valve Wizard) idea. Should I put the grid stopper in before the grid leak, or after it. I notice Rob Robinette puts it after. I have done it both ways and it sounds the same to me, but does it affect the...
by Tonegeek
Wed Aug 14, 2019 2:31 am
Forum: Technical Discussion
Topic: Ampeg SVT issue
Replies: 3
Views: 721

Re: Ampeg SVT issue

xtian: As with any amp, I initially set the bias way cold and pay close attention as the amp warms up. The SVT pro 2 has external bias adjusters and LEDs to help you set proper bias. Long story short- I got another sextet of tubes, this time Sovteks and plugged them in. I was initially able to set a...
by Tonegeek
Sat Aug 03, 2019 1:44 pm
Forum: Technical Discussion
Topic: Ampeg SVT issue
Replies: 3
Views: 721

Ampeg SVT issue

I retubed an SVT 2 pro with Tung-Sol Reissue 6550 that was working when it came in. I also replaced the 3 tubes on the driver board. It promptly went into protection mode on power up. So, I tested all the 6550 tubes and they check out fine. Even put the old ones back in and it worked. My thinking is...
by Tonegeek
Sat Sep 26, 2015 12:50 am
Forum: Trainwreck Discussion
Topic: Trainwreck express big troubles! Red plating
Replies: 7
Views: 2620

Re: Trainwreck express big troubles! Red plating

Unplug amp and Discharge the caps!!!! If you are also having bias issues (red plating), I would remove the output tubes. Then check the cap can and make sure it is not hooked up backwards. If that checks out, unhook one end of the wire feeding the phase inverter plates and see if the 18k2 pair of re...
by Tonegeek
Wed Sep 23, 2015 2:16 pm
Forum: Trainwreck Discussion
Topic: Pre-Express build questions...
Replies: 6
Views: 2883

Re: Pre-Express build questions...

RJ, I read with great interest about the experiments you spearheaded using printed circuit boards for the Express amps. I have a similar mindset when it comes to building amps. What really gives me satisfaction is to achieve the sound of whatever amp it is that I am trying to emulate, but do it in m...
by Tonegeek
Mon Sep 21, 2015 2:45 pm
Forum: Trainwreck Discussion
Topic: Pre-Express build questions...
Replies: 6
Views: 2883

Pre-Express build questions...

After spending years in TAG's Dumble area, I am now drawn to building something similar to a TW Express. I say "similar" because I have no desire to make a physical clone. I do however want to get the amazing tone of the Express and will stick with what works in terms of small parts, layout and sche...
by Tonegeek
Tue Jun 02, 2015 1:04 pm
Forum: Dumble Discussion
Topic: Alternate parts for D-style amps?
Replies: 11
Views: 3397

Alternate parts for D-style amps?

Dale RN65 resistors seem to be getting scarcer by the minute. Has anyone tried other metal film types as an alternate to the elusive RN65? I would love to also find alternates to the PS series caps. The Vishay MPP caps seem to hold up and sound good, but I have never used them entirely in any amp, o...
by Tonegeek
Fri May 08, 2015 1:41 am
Forum: Technical Discussion
Topic: Marshall DSL 40C schematic needed
Replies: 6
Views: 2692

Re: Marshall DSL 40C schematic needed

Should be on the marshallroadhouse.com fourm NOPE, NO MORE! :evil: Now that a couple of Marshall techs regularly frequent the joint, all recent, currently available amps' schematics have been pulled! Your best bet is to become friendly at either/both the Marshall & My Les Paul forums, get enough po...
by Tonegeek
Wed May 06, 2015 5:23 pm
Forum: Technical Discussion
Topic: Marshall DSL 40C schematic needed
Replies: 6
Views: 2692

Marshall DSL 40C schematic needed

Anyone got a schematic for a Marshall DSL 40C? I have the DSL 100 schemo, but its not close enough. It mentions something about a "rats nest" right on the schematic! How appropriate!

I lose signal after V2. Tubes all good.
by Tonegeek
Tue Apr 21, 2015 5:14 pm
Forum: Technical Discussion
Topic: Help with Ampeg B15n diagnostics
Replies: 21
Views: 3075

Re: Help with Ampeg B15n diagnostics

F UPDATE: I just completed stuffing a MC Classictone bassman tranny into the original Ampeg can. There was one major issue with this process that is a show-stopper for using this tranny in the future. To make the MC fit in the can, you must remove at least one end bell and mounting brackets. When I ...
by Tonegeek
Tue Mar 31, 2015 6:59 pm
Forum: Technical Discussion
Topic: 5150 on bench
Replies: 10
Views: 2901

Re: 5150 on bench

All this time I've been doing it the hard way! Actually it does not take that long to drill them out. Hardest part is getting the old rivet past the mounting ears on the tube sockets. However, I will try this other method next time a I get a 5150 or Ultra in for repair. If you have to change the scr...