Horrible hum in Dark Terror

[GreatCthulhu]

Hello friends,

Annoying issue with my recently-acquired Dark Terror (an "upgrade" from a Tiny).

Specifically, my cab (Orange 1x12) emits a LOUD 60hz hum whenever the amp is plugged in and powered on in both 7watt and 15watt modes. Interestingly enough there is no real difference in volume between the two modes.
This hum is present even before a cable/guitar is plugged in (I'm familiar with instsrument noise, being a metalhead, and can work around that with gates etc).

I've had the tubes and electrics checked out -- no problems. I've tried plugging the amp into every outlet and power strip in the house: it doesn't go away. I've tried cheater plugs, power strips, everything my dim mind can manage, and still the same HUM (did I mention it's LOUD?) I never had this problem with the Tiny T, or my other heads (Vox night train, H&K Tubemeister 18)

So I can only assume one of two things: 1. some problem with the cab that makes it overreact to the DT's preamp; 2. shitty wiring throughout my place, which is not out of the question (I live in NYC and am unfortunately familiar with poorly-wired buildings and just a general shoddy standard of workmanship.)

I'd deeply appreciate any suggestions or guidance that anyone could provide. I totally love the DT's tone, it's perfect for what I do and means I can take various stompboxes (eg Big Muff) out of the signal path. I could go to the guitar store but they'd probably just try to sell me a few hundred worth of Monster cables.

Thanks in advance friends!

[Geosh]

Check the tube for the effects loop. I had a similar issue with my Jim Root terror recently and it was all due to that tube. Swapped it and now the amp is dead quiet.

[Jondog]

Theres been some reports of possesed amps from Orange. Serious. https://m.facebook.com/home.php?__user= ... =589020523

[onetracker]

Check the tube for the effects loop. I had a similar issue with my Jim Root terror recently and it was all due to that tube. Swapped it and now the amp is dead quiet.

thank you so freekin much for this post!

I have been chasing this hum in my th30 for a while. I would have sworn it was the outlet cuz the hum got worse after I moved stuff around. I went back and forth with cables, etc and was pretty frustrated.

after reading your post I came home today and swapped out that at7 in the effects loop and when I turned the amp on I thought I left it standby it was so quiet!!! the tube I had in there was a 'vintage' rca....probably from an old TV but tested 'good'

thanks a million!

OT

[Geosh]

Check the tube for the effects loop. I had a similar issue with my Jim Root terror recently and it was all due to that tube. Swapped it and now the amp is dead quiet.

thank you so freekin much for this post!

I have been chasing this hum in my th30 for a while. I would have sworn it was the outlet cuz the hum got worse after I moved stuff around. I went back and forth with cables, etc and was pretty frustrated.

after reading your post I came home today and swapped out that at7 in the effects loop and when I turned the amp on I thought I left it standby it was so quiet!!! the tube I had in there was a 'vintage' rca....probably from an old TV but tested 'good'

thanks a million!

OT

Glad it helped! I had switched out phase inverters, and V1 & V2 in my amp twice trying to fix it. I didn't think that the effects loop tube could be the issue as I thought it was only in the circuit when the loop was used... then I saw the schematic.

[Bato001]

Same problem with a brand new OR15. Humming like crazy out of the box. I tried switching out V1 and V2 as well as the PI with no resolution. Switched out the FX loop tube and the hum magically disappeared.

[Steve Naples]

What tube is everyone using to get rid of the hum?

[davebolden44]

like what brand?

[Steve Naples]

Yes, what brand of 12AT7 is working for you?

[davebolden44]

just get some jj's or electro harmonix. they are all made in the same places so any new tube should function better

[Steve Naples]

Ok, I do have a nice NOS 12AD7, which might work well for the effects loop. I'm not using it for anything else.

[a.hun]

Ok, I do have a nice NOS 12AD7, which might work well for the effects loop. I'm not using it for anything else.

Andy.

[Steve Naples]

I was thinking that a 12AD7 was a good substitute for a 12AT7, but it looks like it is more of a sub for 12AX7, same gain factor. So probably not a good choice for effects loop.

[Randy Bass]

I was thinking that a 12AD7 was a good substitute for a 12AT7, but it looks like it is more of a sub for 12AX7, same gain factor. So probably not a good choice for effects loop.

It would actually be a very good choice for loop, reverb, or phase inverter since it is a low-noise variant of the 12AX7 as long as the extra gain isn't a problem. It would probably depend on the particular amp more than anything.

[Steve Naples]

The only problem that I see, is that the heaters draw a good bit more current on them than a 12AX7, I think 12AX7s draw 100mA and these draw 225mA.
Might be a bit too much for the PT.