3ch Dual Recto, ch2 modern faulty

[Pete05]

Hi, I noticed a serious issue with my 3ch Dual Rectifiers channel 2 when using the modern mode.
When turning the Presence all the way up (It starts already at 12:00) it kills all the high frequencies from the signal and makes the amp sound
like playing under water. Clearly a fault, no amp should sound like that with any settings. :evil:
This happens only when the loop is active (Eventhough it is set to other than channel 2) and in channel 2 in 'modern' mode. Not in channel 3 eventhough those are identical except the presence pot value.
With loop system deactivated, vintage mode... No problem. :roll:

When compared with an another similar in the store (Amp is less than 1 year old) the problem was identical!! :shock:
So, it was not just my amp that had useless channel 2 in modern mode.

Is anyone else having these issues, or are those just small number of Rectos having some faulty components? :?:

Another interesting phenomena is that when all the volumes are turned down the distortion channels leak to the
output, except when turning the channel 2 presence all the way up. Don't remember if there was any difference between channels 2&3
Sounds like a grounding issue or something in the design itself.

 

[daveyboy]

This is at a way low volume I'm guessing correct? I've noticed that phenomena as well. I may have even made a post if memory serves. If you turn the overall output up a little bit the issue goes away and the presence pot will work correctly, left-dark, right-bright.

 

[daveyboy]

Here is my post from a bit back.

Apparently everyone thought I was nutz teehee.

http://forum.grailtone.com/viewtopic.php?f=24&t=32441

 

[Pete05]

This is at a way low volume I'm guessing correct? I've noticed that phenomena as well. I may have even made a post if memory serves. If you turn the overall output up a little bit the issue goes away and the presence pot will work correctly, left-dark, right-bright.

Yes, I noticed this first time when I brought the amp home and played with lower volume level. However, before that I used the ch2 always in vintage mode and never tested the ch2 modern with higher volume. In the local Mesa store where we tested the amps, the volume level was already higher that I would use in home. I was just surprised that the issue never occurred in ch3.

It must be related to the master volume in parallel with the ch2 presence control as bypassing the loop bypasses also the output volume control and the amp works fine.

As it looks like that is typical for Rectos I will need a Hotplate when playing with that amp at home...Or use only ch3.

Thank You for clarifying this issue.