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PostPosted: Tue Nov 07, 2017 9:19 pm 
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Mark II
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Inspired by the Triple Crown's "Tight" switch on their overdrive channels, and in an effort to rid myself of using a boost pedal once and for all, I've decided to take on modding my OG 3 channel Triple Recto. I've read the Pre500 tone thread, got a copy of the schematic, and have been (slowly) teaching myself the basics of tube amp circuits and electronics in general. Youtube channels such as Uncle Doug and The Guitologist have been invaluable in my quest for knowledge, as well as Warped Musician and Rob Robinette's site on tube amps. I'm still in the learning phase and probably not quite ready to crack open my amp just yet, but I wanted to run by a few ideas to you guys that have far more experience than I.

The first place I looked at was the cathode bypass capacitors, specifically V1a and V1b. I would prefer keeping CH1 stock, so would changing V1b bypass cap to say .47uf or even .22uf have a dramatic affect in the bass response for the overdrive channels? Or is it better to use successive filtering to achieve a tighter bass response; e.g., changing V1a to .47uf and V1b to .22uf for example?

Next I was looking at the treble bleed cap on the gain pots for CH2/CH3. Even without knowing the schematic or having any knowledge of electronics, it's rather noticeable the increase in bass/mud up past 1-2o'clock. Yet the percussiveness in the 10-12o'clock region is beautiful. So my thought was to half the value of the cap (from .001uf to say, 0.47nf) which would then double the corner frequency. I'm unsure how effective this would work though, since there most certainly would be a loss in gain. Thoughts? FWIW, unboosted I usually run the gain around 2:00 for the type of saturation I need, so there's still a bit of travel to make up for loss from the passive HPF.

Anyway, that's all I have for now. I'd appreciate any wisdom you guys have. Thanks for reading.

P.S. I should point out that I typically only use Modern mode for my gain channels, and even then, almost always on Orange. So another potential mod I would like to do is alter the Red channel to be identical to Orange, but that's for another thread. :-) Moreover, I ultimately want any mod to be switchable, thus I'm looking to simplicity. I love the Recto voicing, I just want to be able to tighten up that fat ass of hers!

_________________
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


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PostPosted: Wed Nov 08, 2017 5:28 am 
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Mark II

Joined: Sun Sep 30, 2012 4:40 pm
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Location: Finland
If you simply want to tighten the bottom-end, just change the first coupling cap (22nf Orange drop) to 4.7nF or even 2.2nF. That will definitely help in that respect. I don't think there's need to tinker with the cathode bypass caps or bright caps on the gain pots. I still recommend bypassing the 100ohm resistors on cathode caps as instructed in the pre-500 mod thread and see if you like it that way.

And be aware that you're dealing with high voltage electric circuit. You can zap yourself pretty badly if you're not careful.


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PostPosted: Wed Nov 08, 2017 10:52 pm 
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Mark II
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Hm, cool idea! I'm unsure of how to calculate the HPF created by V1a coupling cap and the filter network proceeding it. The 2 parallel resistors form 520K, but what about the 2M2 resistor to ground? I realize it doesn't really matter (just plug in values until it sounds good) but I'd like to have an idea of what the frequency response is/will be.

Duly noted about high voltages. :shock:

I do plan on jumping the 100 ohm bypass resistors. In theory they don't make too much difference, but we'll see; it seems everyone who removes them loves the increase in definition. I'll looking into make it switchable.

_________________
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


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PostPosted: Thu Dec 07, 2017 9:59 am 
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Mark II
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Location: West Chester, PA
To follow up, last night I had a few hours to mess around with mods. I finally grew a set of balls (i.e., felt comfortable enough to discharge the filter caps, test that the circuit has no voltage, etc...) and took a crack at tweaking my TR.

First, I swapped the clean channel's gain pot (1Meg) and Red's gain pot. Immediately noticed a shift in the gain structure. Higher strings (G,B,E) felt less choked and the response overall felt a bit more compressed and easier to play. For high gain metal, this is a great change.

The downside was the "usable" gain range, for me is about 9:00 - 11:00. Below 9, there's basically no signal. Around 9 is a nice crunch type of gain - good for hard rock I guess. Past 11, it's all out saturation - too much for tight metal rhythms. Although the window may seem small, it's not hard to find the right amount of saturation. With the normal 250K pot I actually found the sweet spot tighter, somewhere around 1:30-2:00.

Although the feel and aggression has changed for the better (to me), it did lose some of the bloated Recto voice. I understand why Mesa chose to go with a 250K pot. Stock has a much wider sweep of usable gain for a many styles.

So, now with the gain pot swapped out, the low end got a big more wooly, so I had to trim back some low end pre-saturation. So I removed the first two 100 ohm resistors on cathodes V1a and V2a. I left the third one in, figuring most of the saturation is happening before that stage.

The difference was noticable, but not nearly as dramatic as others have reported.

My next step was to trim more bass. I only have electrolytics on hand so I decided to change out cathode bypass cap on V2a for a .22uf. That REALLY helped tame the low end and low chunky palm mutes are bordering on Mark series tightness. I went with V2a instead of V1a because I didn't want to mess with the clean channel's response (unless I have to). V2a switches in a 15uf in parallel when CH1 is selected. 1uf vs .22uf in that case won't make audible difference. That said, if in the future I want to tighten up the bass response further, I'll try a .47uf at V1a.

The last mod was remove C20. That gave the top end a bit more of a "greasy" tone and brought out a little more pick attack. Small change, but recommended.

I still hear a bit of grunge in the low end, but so far I'm pretty pleased with the results. The real test will be at next rehearsal when I can really open the amp up.

Thanks for looking!

_________________
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


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PostPosted: Thu Dec 07, 2017 4:27 pm 
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Mark II

Joined: Sun Sep 30, 2012 4:40 pm
Posts: 134
Location: Finland
Good to hear you got nice results. And I agree about the gain pot. I would see Recto's gain pot as an improvement over SLO's 500k gain pot. There's much more useable range with Recto's gain pot with different tonal options.

dtrax wrote:
So, now with the gain pot swapped out, the low end got a big more wooly, so I had to trim back some low end pre-saturation. So I removed the first two 100 ohm resistors on cathodes V1a and V2a. I left the third one in, figuring most of the saturation is happening before that stage.

Actually, those two stages are that the last ones to saturate. The cathode follower at V3b is the first stage to saturate, followed almost equally fast by V3a.

I did some Waveform simulation on LTSpice to demonstrate how Recto distorts with gain set around noon (input signal: 200mV 400Hz sinewave):

https://image.ibb.co/dV4ueb/Recto_clipping.png

If you turned the gain pot down, V2a would clean up first, much later followed by V2b cold clipping stage.


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PostPosted: Fri Dec 08, 2017 12:06 am 
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Mark II
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Location: West Chester, PA
Shemham wrote:
Good to hear you got nice results. And I agree about the gain pot. I would see Recto's gain pot as an improvement over SLO's 500k gain pot. There's much more useable range with Recto's gain pot with different tonal options.

dtrax wrote:
So, now with the gain pot swapped out, the low end got a big more wooly, so I had to trim back some low end pre-saturation. So I removed the first two 100 ohm resistors on cathodes V1a and V2a. I left the third one in, figuring most of the saturation is happening before that stage.

Actually, those two stages are that the last ones to saturate. The cathode follower at V3b is the first stage to saturate, followed almost equally fast by V3a.

I did some Waveform simulation on LTSpice to demonstrate how Recto distorts with gain set around noon (input signal: 200mV 400Hz sinewave):

https://image.ibb.co/dV4ueb/Recto_clipping.png

If you turned the gain pot down, V2a would clean up first, much later followed by V2b cold clipping stage.


Wow, thank you so much for that! I see I have much to learn. 8) Those graphs really help visualizing the response of the amp.

Before I checked this thread tonight I swapped V1a bypass cap to .47uf. The low end is stop on a dime tight (EMGs help there, too) and damn close to - if not better than - the response and aggression of using a tubescreamer in front of the amp. Which ultimately was my goal: achieve the same tightness without the solid state garbage feel and tone. Really close now.

I'll turn my attention to V3a. Jumping the 100 ohm on the cathode because why not. I'm thinking .47uf as the bypass cap, but I really need to open the amp up to get a real test of the low end response. So far I've been guesstimating at conversation volume, going from memory of the low end resonance when using a boost pedal.

Back to tweaking I go! :twisted:

_________________
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


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PostPosted: Wed Dec 13, 2017 8:28 pm 
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Mark I

Joined: Sun Sep 13, 2009 10:29 pm
Posts: 39
Location: Portland ME
I would love to tighten up the amp and leave channel one alone as well. Please post up pictures and final values when you are satisfied with the amp.

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Triple Rectifier Solo, Stiletto 412

Past, Mark V, Rect-O-Verb 50 series II, Mark III


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PostPosted: Thu Dec 14, 2017 11:25 pm 
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Mark II
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Posts: 75
Location: West Chester, PA
JSutter wrote:
I would love to tighten up the amp and leave channel one alone as well. Please post up pictures and final values when you are satisfied with the amp.

Will do. I havn't messed with my amp since my last post but plan to this weekend. Thanks for your interest!

I should point out that I'm "tuning" these mods based on my gear, my playing style, and the tone I hear in my mind. That likely be quite different than you or others, but I'm more than happy to share my experiments. I just don't want to give any false hope. What works for me may sound like dogsh!t to you! :lol:

As far as gear that I'm using, it's my RG7 w/ an EMG 81-7 and an Ibby RG920 w/ a Tonezone. EMGs are rather lean in the bass, but the TZ has monster low end response. I'm trying to get it where both guitars sound tight, but I'm primarily focusing on tuning the amp with my 7.

Anyway, after living with the mods for about a week, here are my thoughts:

- reinstalled C20. It wasn't a night and day change, but the added brightness sort of killed the Recto voicing. At gig volumes it was rather harsh. I should note that I now run my amp with loop bypassed (which is noticeable beefier/darker/less fizzy than with) and it was still too bright. But try it out if you think your amp isn't bright enough.

- I'm on the fence about the 1M gain pot TBH. Sure, the tone is a bit more mid aggressive. The attack a bit more pronounced, leads feel effortless. But it loses the Recto grunt that I love. Red Modern w/ 1M gain pot is, to me, more of a high gain Lead voicing. Which, thinking about it now makes the amp more versatile (rather than 2 nearly identical overdrive channels). And since I run Orange Modern for heavy rhythms I'm not losing anything by leaving it in. That said, my mods are focused on getting Orange Modern (w/ stock gain pot) tight as possible.

- The sub lows are still present and need to be tamed a little further. Shemham recommended swapping the coupling caps initially - the only reason I haven't is because I don't have any on hand and got the itch to start tinkering lol. That said, I'll order a variety of 600V orange drops and try it out. I "think" the reason the smaller cathode bypass caps didn't reduce enough low end is because they act more like a shelving EQ than a high pass filter.

- I plan on messing with the Output and Solo circuit. Looking at the schematic, the Output pot has a bright cap and series resistor that is definitely contributing to the tone suck I hear w/ the loop engaged. Also the preceding gain stages (V4a, V4b) seem rather benign from a tone stand point, but adding 2 GS's will never be 100% transparent.

- I'm also planning on hot rodding CH1 and making it a Mark Series style crunch channel. That should be fun lol :twisted:

_________________
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


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PostPosted: Sat Dec 16, 2017 5:55 am 
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Mark II

Joined: Sun Sep 30, 2012 4:40 pm
Posts: 134
Location: Finland
dtrax wrote:
- The sub lows are still present and need to be tamed a little further. Shemham recommended swapping the coupling caps initially - the only reason I haven't is because I don't have any on hand and got the itch to start tinkering lol. That said, I'll order a variety of 600V orange drops and try it out. I "think" the reason the smaller cathode bypass caps didn't reduce enough low end is because they act more like a shelving EQ than a high pass filter.

I noticed that you don't seem to use Vintage mode at all although majority of the dominant sub lows come from lack of NFB on Modern mode. If you wanted, you could try modding Vintage mode closer to Modern mode by locating the 47k NFB resistor and swapping it with 100k or even 150k resistor.


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PostPosted: Wed Dec 20, 2017 12:59 pm 
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Mark II
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Location: West Chester, PA
Shemham wrote:
dtrax wrote:
- The sub lows are still present and need to be tamed a little further. Shemham recommended swapping the coupling caps initially - the only reason I haven't is because I don't have any on hand and got the itch to start tinkering lol. That said, I'll order a variety of 600V orange drops and try it out. I "think" the reason the smaller cathode bypass caps didn't reduce enough low end is because they act more like a shelving EQ than a high pass filter.

I noticed that you don't seem to use Vintage mode at all although majority of the dominant sub lows come from lack of NFB on Modern mode. If you wanted, you could try modding Vintage mode closer to Modern mode by locating the 47k NFB resistor and swapping it with 100k or even 150k resistor.

Funny you should mention that. I've been thinking about disconnecting the Solo circuit and installing a Resonance pot (or variable NFB) for Vintage mode. I haven't gone down that road yet because when using Orange/Modern to power my Studio Pre, the tone is tight and resonant but not as "sludgey" as the Recto preamp. That said, I've also modded my Studio Pre (close to MKIIC+ specs) to tighten up the low end.

My cap order should be here tomorrow and I'll play with coupling caps.

In the meantime did some experimenting with the FX Loop circuit. Ended up removing and jumpering the 47pf cap on the Output pot. This brought back most of the "body" that the circuit sucks out. The fizzy top end is still there however. I've since been using the FX Loop/Output again and simply adjusted the tone stack and presence to compensate for the boosted high frequencies. I've conceded that Rectos are not smooth sounding amps, and that I'll just use my Studio Pre for lead tones. 8)

I also removed the 2M2 load resistor after V1a. This didn't have a profound affect, but I kind of feel the pick attack is a little more pronounced. Tough to say, honestly. I'm leaving it out for now because I dig the tone of my amp ATM.

Also modded CH3 tone stack to the CH2 specs. Just remove the 180pf cap and jumper the 10M resistor. I would have removed the resistor, but that area of the board is TIGHT. Not worth the collateral damage.

Oh, and for the hell of it, I installed a 100K pot on CH3 gain. Interestingly, the attack is softened quite a bit but the saturation is generally about the same. Imagine a cross between Modern and Vintage. Super smooth sustain though. Not really usable (for me), just curious how it would sound. :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


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PostPosted: Sat Dec 23, 2017 11:46 pm 
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Mark II
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Location: West Chester, PA
Here we go boys. My modded TR in it's Final Form. https://soundcloud.com/user-21622482/modded-triple-recto-test-v1-redmodern

I'm not saying I'm done, but for now I think I'll give this project a rest. I learned quite a bit (which was the point, aside from having my amp sound kick ass) and I'm pretty pleased with the results. It's impossible to capture what the amp sounds like in the room, much less the feel of playing it. I'm wasn't able to 100% capture the response of using a boost pedal, but it's damn close. BUT, the best part is the FEEL is organic. Just tight as hell (for a Recto, at least). No solid state harmonic haze. Just toobs.

My soundclip is sloppy, but it doesn't matter. Hope you can hear the changes that were made. When I get some time I will take a few pictures of the PCB to help illustrate what was done. Oh, the guitar used was an RG7 with EMG 81-7. No pedals. Just guitar, cable, amp, cab, mics.

Anyway, here's the mods:

- Change V1a cathode bypass cap to .47uf
- Jumper 100 ohm series resistor on V1a cathode cap
- Change V1a coupling cap to .0022uf
- Remove V1a 2M2 load resistor
- Change Gain pot to 1M audio. I chose to change only Red Channel. The stock 250K pot sounds more like a stock Recto.
- Jumper 100 ohm series resistor on V2a cathode cap
- Change V2a coupling cap to .0022uf
- Jumper 100 ohm series resistor on V3a cathode cap
- Jumper 10M resistor in CH3 tone stack.
- Remove 180pf cap in CH3 tone stack. Note these last 2 mods are to clone Red to Orange. Simply a matter of taste. I never liked the boosted mids of Red/Modern.
- Remove 10pf cap on CH3 Master pot
- Jumper 47pf cap on Output pot

Any questions, comments, or suggestions let me know!

_________________
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


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PostPosted: Mon Dec 25, 2017 3:13 am 
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Mark IV

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How big of a change was that cap on the Output?

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PostPosted: Mon Dec 25, 2017 5:45 am 
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Mark II
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dtrax wrote:
JSutter wrote:
I plan on messing with the Output and Solo circuit. Looking at the schematic, the Output pot has a bright cap and series resistor that is definitely contributing to the tone suck I hear w/ the loop engaged. Also the preceding gain stages (V4a, V4b) seem rather benign from a tone stand point, but adding 2 GS's will never be 100% transparent.


Have you done this fx loop mod?

I don't like the sound of my Recto with loop engaged (I also did parallel to serial mod), so I'd like to modify it to make it sounds clearer.


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PostPosted: Tue Dec 26, 2017 1:38 pm 
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Mark II
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@ afu: It restored some of the body of the tone (say 100-200Hz area). I don't understand why exactly, because I figured that cap was responsible for the "fizz". I still have much to learn apparently. :cry:

@ DS-1: I have not done any FX Loop mods, other than jumpering the cap on the Output pot. I'm with you, Loop Active definitely changes the tone for the worse. That said, with Loop Active, keeping the channel master in the 10-11:00 area and rolling back the Treble/Presence gets me approximately the same tone as with Loop Bypassed. Also, I keep the FX send at noon. I've tried the "trick" where you dime to Send. It's sort of cool (compresses the mid range), but forget about using FX. It'll just clip the input to hell. Moreover, you can achieve the same thing by diming the channel master. I digress...

Happy holidays, boys and girls!

_________________
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


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PostPosted: Tue Dec 26, 2017 2:47 pm 
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Mark II
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Posts: 121
dtrax wrote:
@ afu: It restored some of the body of the tone (say 100-200Hz area). I don't understand why exactly, because I figured that cap was responsible for the "fizz". I still have much to learn apparently. :cry:

@ DS-1: I have not done any FX Loop mods, other than jumpering the cap on the Output pot. I'm with you, Loop Active definitely changes the tone for the worse. That said, with Loop Active, keeping the channel master in the 10-11:00 area and rolling back the Treble/Presence gets me approximately the same tone as with Loop Bypassed. Also, I keep the FX send at noon. I've tried the "trick" where you dime to Send. It's sort of cool (compresses the mid range), but forget about using FX. It'll just clip the input to hell. Moreover, you can achieve the same thing by diming the channel master. I digress...

Happy holidays, boys and girls!


I also tried to keep the master level as low as possible, using SEND at max and OUTPUT as needed.

I have channel 2 and 3 masters lower than 10 o clock. This because I should then put the clean master at 11-12 (and the gain clean also at 12) to match the volume and it starts to have a sort of crunchy sound.

What exactly does the cap on output?

I have a stock 3ch Triple Recto. What mod can I do to have a "2ch" similar sound?

Thanks!


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