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Mini Rec - harmonic/octave distortion on LOW E string
http://forum.grailtone.com/viewtopic.php?f=24&t=73327
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Author:  mikeller [ Mon Apr 03, 2017 8:58 am ]
Post subject:  Mini Rec - harmonic/octave distortion on LOW E string

I rarely play my mini rec - I usually carry at as a backup to my main rig in case something would go down at a show. That said periodically I will fire it up and make sure all is in good order.

Yesterday was that day. The low string E string, and in particularly the lower pitch notes on that string were making a very audible overtone - I noticed it on the Clean channel. I didn't think to try it on the second voice of that channel, and I didn't notice it on the vintage gain channel, although the gain could have been covering it.

What I heard was a harmonic overtone, almost like a fifth down.

Does that sound like a power tube, or preamp tube? Any suggestions would be very helpful!!!

Thanks in advance

Author:  afu [ Mon Apr 03, 2017 7:55 pm ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

It could be. Check the manual for the tubes used by the clean channel. You might also check if your pickup is too close to the strings. That can also affect the harmonics and cause strings to sound out of tune.

Author:  Nick79 [ Tue Apr 04, 2017 6:54 am ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

I had a similar thing with my F50, changing the pre amp tubes sorted it out.

Author:  mikeller [ Tue Apr 04, 2017 6:25 pm ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

Thanks - will try the pre-amp tube(s) first.

BTW - ruled out guitar because I tested that with my Electra-Dyne head.

Author:  mikeller [ Sat Apr 08, 2017 11:37 am ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

Well, it must be something other than tubes - I swapped in a new pre-amp tube, one by one, no change. Then a new set of EL84's - no change. Different speaker cabinet, no change and different guitar, no change....

Trip to the tech is in order now!

Author:  mikeller [ Wed Apr 26, 2017 10:47 am ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

Back at this trouble shooting with an important discovery: it is fine when I switch the effect loop off. I have replaced V5 with several brand new tubes, no difference. Any ideas what would cause that?

https://soundcloud.com/mikekeller-2/mini-rec

Author:  mikeller [ Wed Apr 26, 2017 2:15 pm ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

Time to eat crow....

Thanks to some assistance from Mesa - the amp is perfectly fine. I had the clean channel gain turned up pretty high (in an effort to get a small amount of grit) with the bass up to far. Backing them off and amp is behaving as it should.

Thank you

Author:  KH Guitar Freak [ Thu Apr 27, 2017 5:20 am ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

mikeller wrote:
Time to eat crow....

Thanks to some assistance from Mesa - the amp is perfectly fine. I had the clean channel gain turned up pretty high (in an effort to get a small amount of grit) with the bass up to far. Backing them off and amp is behaving as it should.

Thank you


That can definitely happen on any Mesas as far as I know

Author:  tbonesullivan [ Thu Apr 27, 2017 9:26 am ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

Not just on mesa amps. Turning up the bass all the way on any amp with gain up high can cause strange things to happen. Sounds like it was being overdriven a bit by the bass, so extra harmonics were generated.

Author:  Given To Fly [ Sat Apr 29, 2017 11:05 pm ]
Post subject:  Re: Mini Rec - harmonic/octave distortion on LOW E string

:shock: That is really weird, yet fascinating! It makes me realize how little I actually know about amplifiers and what they are capable of doing, for better or worse. :lol:

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