Orange Dual Terror Hum/Buzz

ChrisNoise · Post by **ChrisNoise** » Thu Dec 08, 2011 3:08 pm

Hey,

I hope someone with better technical knowledge than mine can help me out here. I'm running my dual terror into a PPC212 close back cab @ 16 ohms and I'm experiencing a lot of hum/buzz when I'm not playing. Slightly moreso on the tiny terror channel than on the fat channel. It doesn't seem to be an issue with the guitar as I've tried a few different guitars and its still experiencing the same problem. I've had a few suggestions that it could be an earthing problem. If this is the case how easy is it to fix yourself or would people recommend taking it to someone? I'm based in Ireland so amp techs are a bit harder to come by.

Thanks,
Chris

SGJarrod · Post by **SGJarrod** » Thu Dec 08, 2011 9:11 pm

if the noise is mainly on the TT channel I would try replacing the pre-amp tube for the TT channel first...V1...use something highgrade..this is the first tube in the signal chain and if it has noise the other gain stages will just amplify the noise

V1 is closest to the input jack... so facing the front of the amp it's : V4, V3, V2, V1

V1- 1st half of tube is the 1st gain stage of both channels
2nd half of tube is the 2nd gain stage of the Tiny Terror channel

V2- Phase inverter for the Tiny Terror channel

V3- 2nd & 3rd gain stage for the Fat Channel

V4- Phase Inverter for the Fat Channel

ChrisNoise · Post by **ChrisNoise** » Fri Dec 09, 2011 11:20 am

Thank a mil for the response. Very informative. I'll have a shot at it and see what can be done.

ChrisNoise · Post by **ChrisNoise** » Fri Dec 09, 2011 12:40 pm

Just to check. In the dual terror are the tubes paired? Will I have to replace two of them in one go? If so which is paired with which? I'm relatively new to Valve amps so I just want to be sure!

Is there any pre-amp tube or are they all power tubes?

Thanks,
Chris

Pens · Post by **Pens** » Fri Dec 09, 2011 4:01 pm

Don't have one, but specs say they have 4 pre-amp tubes (lil ones) and 4 power tubes (big ones).

Big ones are paired, lil ones never are. Since he's talking about swapping the pre-tubes, you just need to get the lil ones, that aren't matched.

Valves: Preamp - 4 x ECC83; Output - 4 x EL84

SGJarrod · Post by **SGJarrod** » Fri Dec 09, 2011 4:36 pm

yarp...what PanPan said.......

the small tubes in the front are the Pre-amp tubes and are what I am referring to as V1-4... they are not matched...

The 4 big tubes in the back are the power tubes and are matched...

I would just buy a really good 12ax7 (Ecc83) to replace V1 to give a go.... as V1 is all the gain stages for the TT channel... Right now I am running all TAD tubes in mine and am very happy...although the TAD EL84's get much hotter than most EL84's

if that does not solve the issue then I would go down the Ground/ Amp Tech Route.... but in most cases its the tubes, especially if ur still running the cheap Chinese tubes that come in it

Mattsican · Post by **Mattsican** » Mon Mar 09, 2015 10:09 pm

Kinda bringing up this old topic. I ordered a ecc81 for my DT and put it in the V3 slot (from what i was reading on here) and it sounded good. I put it in V1 to see how it would sound and holy shit it sounds good. The gain knob is actually useful in stead of being an "on/off" switch. REALLY diggin it. Once question tho, i was looking at all the preamp tubes and the stock ones were JJ's. 3 said ECC83S and one just said ECC83 (the one that was in V1). whats the difference? i tried to google info but all it was was it had to do with spiral winding. why would the non-S be in the V1 slot?