Mid-Boost Tone Stack

Started by Heady Jam Fan, December 13, 2012, 02:28:18 PM

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Heady Jam Fan

I just bought a Silverface Deluxe Reverb and I am trying to figure out how to achieve a mid-boost, a la Trey's DR.

I found this online: http://amps.zugster.net/articles/tone-stacks
I might try to implement the Baxandall tone stack in the amp when I get it.

Here are the details on the specific amp:
Quote1976 Fender Deluxe Reverb. Completely BLACKFACED. New Mercury Magnetics power transformer. New (matching) plate resistors and cathode resistors. New Sprague Atom filter caps. All components out of specs have been replaced with premium replacement parts. New Ruby 6V6 power tubes with fresh bias adjustment. Newer Mesa preamp tubes. Original speaker. Okay cosmetic condition with some scratches on faceplate. Back panels are mojotone replacements. Includes reproduction footswitch.

Amp has mid control mod and tremolo disconnect mod (SRV). Both mods are completely reversible if you want, but really add a lot to this amp. No additional holes were drilled into chassis.

It does have a mid-control, as you can see from the above description, but I am assuming it is a Fender-style midrange control that acts more like a volume control (I emailed the seller to find out, haven't heard back yet).

I was just wondering if anyone had any experience with this? Also, I have to decide if I would want to do something like this on both channels or just the lead channel.
Headless Hollowbody > Mesa Boogie MK III > TRM Trucker 212 w/ V30's
Whammy 5 > Mini Wah > 74 Script Phase 90 > CP9Pro+ > 82 TS9 > 83 TS9 > Ross Compressor > Turbo-Tuner > 83 AD9

Heady Jam Fan

#1
I was talking to a local guy who does amp tech work on his free time and he suggested some changes to the James Tone Stack (I guess the James is similar to the Baxandall). I think the changes he suggested were from Merlin's amp book.

The changes still have the same shape frequency plot as the James, but peak at -9db rather than -16db - much less volume loss:

https://docs.google.com/open?id=1bur5pN5LCogL06lCoSZBDq9TPtlpzwG4woyORFUTsH13zF3hMU7q0wEKYqkT

I have to decide if I want to work with the local fella who suggested this and do the mod on my amp, or if I will just use an EQ pedal. Pro's of an EQ pedal are that I don't have to do further mods on the amp even though it will only cost a few bucks in parts - this also means I can leave out the V1 or V2 preamp tube, making the opposing channel stronger sounding (and I save money on tubes over the long haul). On the other hand, that means I would need to power another pedal rather than using a passive a/b box. With the modified James circuit, my amps EQ would be flat with the treble and bass knobs at 12 o'clock, so even if I do the mod, I can go from mid-hump to flat to scooped. It would be cool to see if this mod gets close to what the Red guy's amp sounds like, but could also be farther off than the frequency plot suggests and might take quite a bit of tweaking if I really want to hit the nail on the head.

Anyway, not sure what I will do, but wanted to share the knowledge in case someone else decides to consider the same thing.

PSA - there is an SFDR on ebay that is going to end really cheap I think, $600 right now, no bids so far. Even with thorough tech-work and a few grill cloth, the price is pretty good IMO.
http://www.ebay.com/itm/281036685739?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Headless Hollowbody > Mesa Boogie MK III > TRM Trucker 212 w/ V30's
Whammy 5 > Mini Wah > 74 Script Phase 90 > CP9Pro+ > 82 TS9 > 83 TS9 > Ross Compressor > Turbo-Tuner > 83 AD9