Problem with Electra Dyne squealing when higher gain

Guerreirox · Jun 10, 2017

Hello all, I recently purchased a 2012 Electra Dyne head in mint condition and am loving it but the amp squeals/feeds back when moderate to high gain is applied. If I turn the volume and master volume past noon on the blue and red channel, it starts feeding back. On the clean channel, I can get distortion using pedals but only at moderate gain levels. As soon as I increase the gain, the amp starts feeding back - even when hand muting the strings.
I thought it was microphonics from a preamp tube but I have replaced all 7 preamp tubes and all 4 6L6s and the feedback still occurs. I put Sovtek tubes all around except Mesa Boogie SPAX7s in V1, V6, and V7 in hopes that it would solve the feedback but still getting same feedback problem. It sounds great otherwise. At this point, I don't know what else to try other than taking it to have it serviced.

Any insight in this matter is greatly appreciated, thanks!

screamingdaisy · Jun 11, 2017

Have you tried switching guitars? Master past 12:00 is pretty loud and might be stimulating microphonic pickups.

Guerreirox · Jun 11, 2017

Thank you for replying, Screamingdaisy. I did try several guitars - both single cool and humbuckers.
Made no difference. I did plug in directly to the amp and the squeal went away on all channels. So, only happens when I have pedals in the chain. I started out by just putting the polutune and the wah - still squeal on blue and red channels. Worse one is the blue Channel. I run both my Mesa amps in stereo through an Empress buffer+ stereo and it helps a bit since it has a noise filter for each amp but still happening. I'll try placing SPAX7 preamp tubes in the remaining positions to see if it helps. BTW, my settings are; Master=12noon, Presence=12noon, Bass=1:00, Mid=1:00, Treble=1:00, Volume=11:00.
Gain pedals work but can't crank up gain knobs. When using pedals, I run both amps clean.

Thanks again for your help.

Eevil · Jun 12, 2017

How are your pedals powered? Could you test with just batteries? I had some strange problems when using same power source for pedals in fx-loop and before amp.

How about cables? I had one cable made from quality mic cable wired "correctly" yet it still made hiss and squeal when used between guitar and amp in higain modes. The cable worked properly in line level use (fx-loop). Wah (at least Crybaby) is notoriously picky with power quality and pedals before it. Does polytune have buffer?

screamingdaisy · Jun 13, 2017

Guerreirox said:
I did plug in directly to the amp and the squeal went away on all channels. So, only happens when I have pedals in the chain.

Knowing that, I don't think your problem is tubes and I'd start going through each pedal and cable 1 by 1 until I found the issue.

Are you running all your pedals out front? Or are some of them in the effects loop?

If you have effects in the loop, are you using an isolated power supply (Pedal Power 2, Iso-Brick, etc)? Or are you using a standard power supply (MXR Brick, Godlyke Powerall, 1 Spot, etc).

Guerreirox · Jun 13, 2017

Yeah, I think it might be the power sources. All pedals going into the Electra Dyne are up front and powered by 2 power bricks. One is a MOSKY Power Station and the other a JOYO Power Supply2. Both cheap and not isolated. Cables between pedals are all either Lava or Evidence solderless and the board is very quiet.
I will definitely try each pedal at a time. I tried both the Polytune2 by itself and the Morley Bad Horsey 2 wah by itself and both had a squeal on the blue channel - especially the wah but only when engaged. So, it has to be the power supplies, right?

I'll have to save and get the Voodoo MONDO isolated power brick.
I have 13 pedals on my board of which only the chorus, delay and reverb are going into the effects loop of the Lonestar Special.

Thank you both for the great ideas, cheers!

Guerreirox · Jun 13, 2017

I found the root of the problem. The metal ends of two cables going into the Empress stereo buffer+ were touching. These were the cable end going into out1 and out2. Glad I won't have to buy the expensive ISO power brick.