WTF is going on (cannot diagnose amp)

[VauxhallandNick]

Hey everyone, thanks so much ahead of time for the help. Every time I have a problem people respond and do their best to help me out and I truly appreciate the love.

Anyway here's the deal.

I have a yamaha G100 solid state 2x12 amp and also a 1970s twin reverb.

They're both having the same problem, at times they will work perfect, but randomly will cut out, lose volume, then get completely distorted and have almost no volume even turned up to 10.

I took the twin in to my tech today (Who is a brilliant dude, worked for fender in the 60's and 70's and knows a ton about gear and fender amps) he checked all the pre amp tubes/power tubes, filter caps, and voltage tested basically everything and then told me it looks perfect and is healthy. I told him about the problem of it cutting out and he said he thinks it may be the current in my household power outlets, however this problem also happened at the rehearsal studio recently. I've tried different cables/guitars/plugging and unplugging the amp etc nothing helps once it goes into the quiet fuzzy state, except maybe after I don't play it for a day and then it will be fine sometimes for days on end.

Anyway on the way back from the shop it dawned on me the both amps were doing the same thing, losing almost all volume and sounding way distorted.

This got me to thinking, could it be an issue that my pedals are overpowering my amp and causing it to burn something or over current it?

I run like 10-12 pedals, all off of a one spot power supply with two daisy chains, one connecting to the one spot and another connecting to the last spot on the first daisy chain, is this a bad idea to do?

Anyway this is the issue that I just can't figure out.

Any help is appreciated, thanks so much.

-Nick

[sonidero]

Make sure you're not over working the One Spot... Check the milliamps cause this is from the website...

"Handles from one to over twenty guitar pedals (1700mA max!)"

You might be close to or over the mA rating...

[Zounds Perspex]

yeah, first see if this happens plugged straight into your amps. 1-Spot seems a likely culprit, though.

[VauxhallandNick]

Will def try going direct in, do you guys know if it's bad to run two daisy chains off of one, one spot?

[Zounds Perspex]

It all just depends on the draw of your pedals.
also, some pedals really don't like being daisy-chained.

[osbornkt]

If you find the same problem occurs after running your guitar direct, have your tech check the main transformer/first few caps in the amps. I've had the same problem with some old amps I've bought, and it usually ends up that the caps right after the power transformer had been overworked in the past or the transformer itself had some sort of damage.
This is super unlikely that the same thing is happening to both amps, however, it does sound like that problem I've where had that was the culprit, so it may be worth a check...

[VauxhallandNick]

Awesome thanks so much. Are filter caps and caps the same thing. He tested the filter caps last time and said they were all great and that both the output and power transformers seemed to be in great shape. He said as far as he could tell the amp was super healthy.

[smallsnd/bigsnd]

definitely test with no pedals.

[whiskey_face]

anytime more then one amp has an issue I start looking elsewhere for the issue

[VauxhallandNick]

SOLVED the issue.

Two of the pre amp tubes had a grounding issue.

Weird the first tech didn't pick that up. Either way it rules now.

thanks so much for the help guys.

[Jero]

...but that doesn't explain why multiple amps had the same issue ???

[excane]

...but that doesn't explain why multiple amps had the same issue ???

This.

I'm very curious as well.

[VauxhallandNick]

I'm still unsure on what's going on with the Yamaha. It's worked fine for the past month or so. However, I was just playing the twin and I got a volume cut a couple times when I would strum a chord rather hard.

Annoying, it's def not a cable or guitar I've tried on multiple guitars and multiple cables and plugged directly in.

[snipelfritz]

Will def try going direct in, do you guys know if it's bad to run two daisy chains off of one, one spot?

I do it Most of my pedals are relatively low mA draw however.

I can't say I've had problems with that.

[Noise...]

Play direct in. I guarantee you won't have the issue on either amp.

I've occasionally seen this in some pedals - especially ones with 3PDT switches. If the switch ends up with an issue, it'll occasionally cut out or cause volume loss as part of it is grounding.

Alternatively, something could have come loose in a pedal and is occasionally grounding out or bridging two points in it.

Once you confirm that the issue is in your pedalboard, add pedals back one at a time until you find the culprit.