Tight High Gain Recto Mods

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dtrax
Mark II
Posts: 79
Joined: Tue Feb 26, 2008 2:23 am
Location: West Chester, PA

Re: Tight High Gain Recto Mods

Post by dtrax » Sat Oct 20, 2018 3:52 pm

afu wrote:
dtrax wrote:
afu wrote:I updated the page regarding the voicing circuit, gain, and load resistor.
Thanks for sharing. Your site is one of the inspirations for me learning about tube amps. :mrgreen:
Thanks, I appreciate that.

FYI, I found that I made a couple of mistakes with the math for the "Design Concepts' articles. There were a couple of really misguided articles I deleted. I hadn't thought everything through as well as I could have, but I've fixed most of it. I'm just really ill all of the time, so my blog has not even taken a backseat, because it's in the trunk.
Jumpering the cap on the Output pot, in practice, restores some of the low end lost when using Loop Active. IOW, it sounds a bit fuller (e.g., less tone suck). In theory I'm unsure why this is TBH. That pot has a 330K resistor in parallel tying the input to the wiper, with said cap in series. In my limited knowledge, I assumed this was a bright cap, but the opposite effect occurred when I jumpered it. It wasn't a night and day difference, but as with most things, small increments here and there contribute to the bigger picture. The brightness/fizziness is still present, but that can be dialed back with the treble/presence pots to some degree. For example, I keep the Treble at 2:00 with Loop Bypassed, but dial it back to 1:00 with Loop Active.
It's a treble bleed. I've done a similar thing on the pot to one of my guitars. You don't have to jumper it. Having both components removed is the best thing for a mod. A jumper will allow a bypass path for a signal.
You're right. And I misspoke (typed?) about jumpering it - I did simply lift it off the pcb.

It's worth the effort for lower volume playing (a bit fuller). For gig volumes I didn't notice much difference. I've always kept the channel master for modern mode somewhere in the 10-11 oclock area. Seems to sound the best and balance well enough with CH1 to get a reasonably clean tone if needed.

One mod I'd like to do is disable NFB for CH1. That would eliminate all volume balancing issues. Plus I vastly prefer no NFB as a whole, for dirty and clean sounds. But I'm not savvy enough to be messing with relays and such. One day... :mrgreen:
Guitars:
Ibanez '98 RG7620 (EMG 81-7H, 60-7H)
Amps:
Triple Recto 3CH (modded), Studio Preamp (MK2C+ mods), 2x12 Recto Vertical cab
Past:
Mark V head, Rectoverb series 2 combo, F-30 combo, V-Twin rack pre

afu
Mark IV
Posts: 662
Joined: Thu Aug 15, 2013 12:20 am
Location: Tucson, AZ
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Re: Tight High Gain Recto Mods

Post by afu » Thu Dec 20, 2018 1:43 am

dtrax wrote: One mod I'd like to do is disable NFB for CH1. That would eliminate all volume balancing issues. Plus I vastly prefer no NFB as a whole, for dirty and clean sounds. But I'm not savvy enough to be messing with relays and such. One day... :mrgreen:
I'm pretty certain that Channel 1 has no NFB. That's why the manual says to use Vintage when slaving an amp into the fx loop; it provides a presence control. I'm not looking at the schematic, but I'm really, really sure.
2007 3 Channel Dual Recto w/loop mod

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