Rectoverb series II - distortion pedals sound like crap

[thehornedone]

I've had my Rectoverb for about 2 years now, and I haven't noticed this until now, after having acquired a fender blues jr. After in depth knob tweaking, I noticed that pushing distortion pedals through the clean channel of the Rectoverb is very very moody. If I get anywhere even close to or above 12:00 on the treble or the gain of channel 1 the tone turns to mush, noise, becomes garbled, etc.

Is it just my amp? Another thing I've noticed is that, compared to the fender, the volume on my distortion pedals makes little difference to the volume coming from the amp. If I set any pedal to 12:00 the bypass tone is always louder than with the pedal on. I have to turn it up to about 4:00 to get it louder than the bypassed tone. With the fender, 12:00 is naturally much louder than the bypassed tone, and 3:00 is probably 2.5 times as loud. This could have to do with the input impedence of the recto. An overdrive pedal through the recto barely changes the volume, but on my fender can probably boost the volume to 3 times as loud. The recto has a ceiling where it just starts getting more distorted but the volume doesn't change.

Can someone else with a recto series head try this out and tell me if you get the same result? Take any distortion pedal, turn the volume up to about 2:00-4:00, and the distortion to about 3:00, then put the recto's clean and gain knobs to 11:00. A looper pedal helps here, but start playing and turn the treble up on the amp slowly and hear the tone turn to crap.

By the way, I have Mesa 6l6 tubes in, but this should make no difference to the interactions of the preamp. My preamp tubes are EHX, and are pretty new.

I think I'm just going to stick with my fender for distortion pedals, it sounds stunningly better and is not moody at all. any master, gain, and eq settings retain a great tone, while changing it drastically. The Mesa's preamp knobs do almost nothing but make it sound like crap if they aren't in the exact ideal settings. The bass past 10:30 makes it sound flubby as hell (as noted in the user guide), the presence just exacerbates the touchiness of the treble knob. Why would they design the treble knob to interact so much with the gain and not the EQ of the signal? Alright, sorry, done ranting.

I used to really love my Mesa, but this fender is making me discover my multitudes of pedals like never before.

 

[mikey383]

The problem here is due to input impedance. If you have one amp that like the volume of the pedal to be at "A" to get to unity gain, and another amp that likes the pedal to be at "B" for unity gain, that's an impedance issue between the amps. Set your pedal accordingly and don't worry about where it's set at.

I'm not surprised that the Recto has a higher input impedance. It's a high gain amp, whereas a Fender is typically a low gain amp. This is one of the reasons amps like Peavey 5150s have hi-gain and low-gain inputs...they account for different pickups, which will ultimately affect the impedance.

 

[94Tremoverb]

It's not do with the input impedance - both amps have an input impedance of 1Mohm, which is "high".

It's because the Mesa has a lot more gain in the preamp, so if you have the gain as high as 11 o'clock - which is almost at the point of break-up, even with a loud guitar - driving it harder with a pedal will make it distort rather than get louder. Worse, because distorted sounds contain more energy across a wider bandwidth than clean ones, even when set to the same level the output of a distortion pedal will probably make the amp break up even sooner, especially in frequencies which don't sound good, ie extreme low and high, which will make it mushy, and harsh. This is why the amp's EQ becomes much more touchy too. *Overdrive* pedals (like the Tube Screamer) are usually deliberately designed to roll off both the top and bottom and boost the midrange, which is why they can sound quite boxy when used into a clean amp, but much better when used to push an already overdriven amp harder. (Yes, I know overdrive and distortion are essentially the same thing in theory because they are both forms of "distortion", but the way the two sounds are used in pedals is totally different.)

I get the same type of problem at those settings on my Tremoverb too. To get it to work better, use as little gain on the amp as you possibly can - turn the channel master right up, and run the volume from the gain, as if you were using a non-MV amp. If that doesn't work, you may need the first stage gain reducing on the amp - this is a simple mod that just involves bridging one resistor in the amp with another - I did it to a friend's Mesa for exactly this reason. The funny thing is that eventually he stopped using pedals into the amp anyway, because the amp's distortion channel just sounds better .

 

[thehornedone]

Thanks for a great response, very informative. The Rectoverb definitely has better distortion than any distortion pedal, but I like to use some wacky fuzz pedals and such. Now I'm considering doing this resistor mod. It probably wouldn't change the sound, right? It would just lower the first gain stage factor.

 

[94Tremoverb]

Yes, that's right. You need to reduce the value of the first gain stage plate resistor, which is 220Kohms as opposed to the 'classic' 100K used in the Fender and almost all other older amps. (Sorry, I can't remember exactly where this resistor is on the board, but it's not hard to find with a beep tester from pin 1 of V1.) If you parallel this resistor with a 180K one, the resulting value is very close to 100K. This will roughly halve the gain.

Be aware that this will reduce the gain of *both* channels, because they share V1A. But there's enough gain on the other channel that you usually don't need it maxed out anyway.

I like fuzz/distortion pedals with stupidly wide-bandwidth sounds too . (eg Frantones) I actually don't even like Tube Screamers really, although I can see they have their uses...

 

[mikey383]

The problem here is due to input impedance. If you have one amp that like the volume of the pedal to be at "A" to get to unity gain, and another amp that likes the pedal to be at "B" for unity gain, that's an impedance issue between the amps. Set your pedal accordingly and don't worry about where it's set at.

I'm not surprised that the Recto has a higher input impedance. It's a high gain amp, whereas a Fender is typically a low gain amp. This is one of the reasons amps like Peavey 5150s have hi-gain and low-gain inputs...they account for different pickups, which will ultimately affect the impedance.

It's not do with the input impedance - both amps have an input impedance of 1Mohm, which is "high".

I need to quit posting late at night after the bar closes.

 

[thehornedone]

Yes, that's right. You need to reduce the value of the first gain stage plate resistor, which is 220Kohms as opposed to the 'classic' 100K used in the Fender and almost all other older amps. (Sorry, I can't remember exactly where this resistor is on the board, but it's not hard to find with a beep tester from pin 1 of V1.) If you parallel this resistor with a 180K one, the resulting value is very close to 100K. This will roughly halve the gain.

Be aware that this will reduce the gain of *both* channels, because they share V1A. But there's enough gain on the other channel that you usually don't need it maxed out anyway.

I like fuzz/distortion pedals with stupidly wide-bandwidth sounds too . (eg Frantones) I actually don't even like Tube Screamers really, although I can see they have their uses...

Ah, yeah, that sounds easy enough. I have a multimeter so I could easily find the right resistor, and I have some 180k resistors on hand as well...but if it lowers the input gain on channel 2, I may not go for it. It would be easily reversible if I don't like it though. I was very close to selling my rectoverb to buy a Traynor YCS90, but I just went to go try one today and now I'm not so sure. It's a very versatile, great sounding amp...but ****...it's just not as beefy and ballsy as the rectoverb, and I don't just mean for high gain stuff. It just feels and sounds a little thinner and cheaper on all settings. Plus, the 90W-25W switch in the back didn't work. It would get quieter for a second than ramp back up to full volume. And I swear: at the full 90W, the traynor wasn't NEARLY as loud as the Mesa is at half main volume. And on the dirty channel the speakers would break up unfavorably at really high volumes. It has some really nice abilities, but the rectoverb is definitely in a different class.