Tight High Gain Recto Mods
- Thread starter dtrax
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Not on an actual Rectifier, but I've compared between 10uF, 20uF and 30uF caps on my SLO/Recto-clone I've built. In my experience, the higher you go, the more punchy, bigger and less compressed the amplifier feels. It feels as if the amp slightly cleans up. The lower value caps provide slightly less bottom-end and make the feel more compressed.DS-1 said:
IMO, the 100ohm resistors on cathodes have somewhat unique effect. They slightly reduce the gain boost that the cathode caps provide and flatten the frequency response. This seems to result in a slightly more pronounced lowend with less upper mids and treble. This in turn increases the hair and grind when e.g. playing power chords which is one part of the Rectifier trademark tone. The price is paid in somewhat dampened attack. If the 100ohm resistors are jumped, there is slight gain increase in the mids and treble.
dtrax
Well-known member
It's been a while since I've been around here. Had some real life stuff going that pulled me away from fun stuff, like modding amps. 8) . Anyway, I figured I should report back having put my amp through it's paces with my band.
Welp, I have to be honest. I've reversed a few of my mods. Fact is, Mesa pretty much "got it right" (no surprise TBH). I did keep some, which I'll go over shortly, but suffice to say that often times the "easiest" answer is many times the "best" answer. And the easiest solution is to just use a **** OD pedal in front of the amp lol.
So what did I reverse? The coupling caps were restored back to .02uf. Yes, using .0022's cleaned up the low end substantially, but at gig volumes the low end was just "off". It didn't "thump" in the right way. Instead it was just sort of boxy and odd. I also changed V1a bypass cap back to 1uf and reconnected the 2M2 load resistor. I kept all the other mods.
So, next up I'm going to mess with CH1 and see where it can go. I want to get more brightness out of it; something more Blackface. Going over the schematic there are plenty of areas to increase the top end. Should be interesting...
TL;DR: Just use a tubescreamer if you play metal with a recto. :twisted:
Welp, I have to be honest. I've reversed a few of my mods. Fact is, Mesa pretty much "got it right" (no surprise TBH). I did keep some, which I'll go over shortly, but suffice to say that often times the "easiest" answer is many times the "best" answer. And the easiest solution is to just use a **** OD pedal in front of the amp lol.
So what did I reverse? The coupling caps were restored back to .02uf. Yes, using .0022's cleaned up the low end substantially, but at gig volumes the low end was just "off". It didn't "thump" in the right way. Instead it was just sort of boxy and odd. I also changed V1a bypass cap back to 1uf and reconnected the 2M2 load resistor. I kept all the other mods.
So, next up I'm going to mess with CH1 and see where it can go. I want to get more brightness out of it; something more Blackface. Going over the schematic there are plenty of areas to increase the top end. Should be interesting...
TL;DR: Just use a tubescreamer if you play metal with a recto. :twisted:
afu
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DS-1
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I have a 2005 3ch Triple Rectifier and I'm doing some tone tests.
I need to use the FX loop on (I've modded it to have a serial loop, I have a lot of modulation pedals and I really like the SOLO function), and I'm experimenting what's the best tone according to my ears.
First, I used a very low master channel for 2 and 3 ch (master is at 11 for channel 2 set to VINTAGE and 8-9 for channel set to MODERN), with cranked SEND pot (very near to MAX level). In this way I can have a very clean channel. I like the sound of the clean channel, but channel 2 and 3 are too scooped. It seems like the mids don't come out due to the low master channel.
If I use different master channel volumes, the situation is a bit different: SEND know at 12, channel 2 at 1 o clock with VINTAGE setting and channel 3 at 10-11 o clock with MODERN setting. These channels now are really crunchy. I lowered the gain a bit, the tone is full of mids. But I can't have a real clean channel, because I need to push it hard to level the volumes with the other two channels (master at 3 o clock, gain around the same setting), but obviously it is WAY TOO cruncky to be a clean channel.
The question is: there no mod for the clean to at least match the volume level of the other two channels? Obviously I have this issue only when I use FX loop on and crank the master volume of the channel 2 and 3.
I need to use the FX loop on (I've modded it to have a serial loop, I have a lot of modulation pedals and I really like the SOLO function), and I'm experimenting what's the best tone according to my ears.
First, I used a very low master channel for 2 and 3 ch (master is at 11 for channel 2 set to VINTAGE and 8-9 for channel set to MODERN), with cranked SEND pot (very near to MAX level). In this way I can have a very clean channel. I like the sound of the clean channel, but channel 2 and 3 are too scooped. It seems like the mids don't come out due to the low master channel.
If I use different master channel volumes, the situation is a bit different: SEND know at 12, channel 2 at 1 o clock with VINTAGE setting and channel 3 at 10-11 o clock with MODERN setting. These channels now are really crunchy. I lowered the gain a bit, the tone is full of mids. But I can't have a real clean channel, because I need to push it hard to level the volumes with the other two channels (master at 3 o clock, gain around the same setting), but obviously it is WAY TOO cruncky to be a clean channel.
The question is: there no mod for the clean to at least match the volume level of the other two channels? Obviously I have this issue only when I use FX loop on and crank the master volume of the channel 2 and 3.
afu
Well-known member
Snow006 said:
I've been using a Boss GE-7 EQ pedal in front of mine. Running it 12V with a crooked frown (max 0dB; min -10db) and the gain up to ~12dB. I now have a Switch DR pedal looper/midi controller to use it only when I need to.
I want a TC Electronic Spark Booster (4 knob) and/or a used Nova Drive for more options and flexibility.
dtrax
Well-known member
DS-1 said:
The reason you're getting more mids and crunch when pushing the channel Outputs (or cranking the FX Send level) is because the tubes down stream of the tone stacks are beginning to distort. I'm not talking about power tube distortion; you're literally overdriving the FX send/return and/or the phase splitter (V4 and V5). There isn't anything wrong with that, but there's no way to get a clean tone when you're slamming those stages.
The volume discrepancy is the lack of negative feedback in the power section when in Modern mode. As you've noticed, if you want to have a truely "clean" channel 1, CH2/3 Modern output needs to be set around 9-10:00 at most.
The best way to get more mids out of CH2/3 Modern is to roll back the Bass. But to get that crunchy tone (from clipping V4/V5) you will have to sacrifice your clean tone.
Thinking about it, you *could* disconnect the NFB relay for CH1 (assuming it's even that easy) - that would give the clean channel a huge boost in volume. Would probably be much louder than Modern mode in fact. But unless you know what you're doing, I wouldn't go messing around as you'll more than likely screw things up.
dtrax
Well-known member
afu said:
Thanks for sharing. Your site is one of the inspirations for me learning about tube amps. :mrgreen:
Oh, and speaking of boosting rectifiers and whatnot... I've started gather parts for a DIY amp build. The power amp is loosely based on a Fender DR (6V6 in p-p). For the preamp however, I'm flirting with the idea of building a SLO/Recto overdrive circuit with an additional gain stage and simplified tone stack tacked on the front end. Basically a Recto/Mark love child. The inspiration comes from the fact that so many Recto users resort to EQs, ODs, etc up front to filter out the lows, why not just build it into the amp itself?! I'll be building each section on separate turret boards so swapping out preamp "cards" should be relatively simple. I'll start a new thread once I get the ball rolling. :twisted:
afu
Well-known member
dtrax said:
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.
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.
The parallel resistor fixes the cutoff frequency of the capacitor into one place. Mesa has it set somewhere around 10 kHz (I'm spit balling). Those are not only helping those higher frequencies through; It's capping them so the power amp doesn't oscillate. Removing both won't cause that issue until the control is at 2:00 or more and the MVs are also cranked. Since that sounds like ****, I don't think it's going to be a problem.
With the bleed removed, the Output should react more like the MV does when the loop is off. As far as I can reason, the difference is that there're now two volume controls, so it should be setup with a low-ish positioning of the Output in mind. I'd first try to set the Output where I want it and increase the MV of my dirt channel until it's loud enough for performance.
This mod is on my to-do list. It's the only thing that I'm going to change, since I've already done the series loop mod.
(edit)
I forgot to mention that the Road King does not have the treble bleed in it. That's my inspiration for removing it.
dtrax
Well-known member
afu said:
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:
afu
Well-known member
dtrax said:
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.
