TH30 problem?

[davieo45]

Hi all,

Im new to this forum so im sorry if this has been asked before. I couldn't really find anything that could help me figure out if I have a problem so sorry in advance. Im new to Orange valve amps and decided on the TH30c. It definitely hasn't disappointed me yet but when I have the amp on full power regardless of either having it on 2 or 4 valves selected, im getting a loud feedback sounding hum from both channels. It doesn't happen on half power so i don't think it is interference. Would it be a valve issue? Its probably due for a valve swap anyway because i bought it used. Any ideas?

[Randy Bass]

I don't know enough about how the pentode / triode switching function works in the amp, but it does sound possible that one of the power valves is microphonic. It's worth having a spare quad of EL84s anyways for the amp, so you might as well order some and plunk them in the amp to see if it fixes the problem. Good luck and let us know how it goes.

[davieo45]

Hey thanks for the suggestion. I will probably order some just to be safe. I let the amp sit on standby for a little while longer maybe another 5-10 minutes and it didn't do it anymore. It is pretty strange. Ive read a bit about the problems people have with this amp so I hope its just a valve issue.

[Jondog]

Did you just buy the amp new? Tubes could be under warranty if so. I think for 3 months.

[davieo45]

No I bought it used. I contacted orange and they recommended changing the power and preamp tubes. Im gonna give it a shot since i dont know how old the amp is.

[davieo45]

Sorry for another question here guys but I was wondering about the different brands of valves they have. From what ive read, the TH30 is a self biasing amp. Is this only with Orange brand valves or with any old valve brand? Thanks in advance.

[a.hun]

Sorry for another question here guys but I was wondering about the different brands of valves they have. From what ive read, the TH30 is a self biasing amp. Is this only with Orange brand valves or with any old valve brand? Thanks in advance.

It is (like many 4xEL84 30 watters) a cathode biased amp meaning that there is a bit of 'self adjust' range for running power valves with different current draw levels. (Different from fully 'self biasing' which doesn't really exist.)

This means that any fairly average range EL84 valves (and not just Orange) should run fine with the amp. What I tend to advise is buying performance matched replacement sets from a good specialist valve supplier and telling them which amp they are for. They should then be able to supply suitable ones.

Only two checks then needed are that they sound good and aren't RED PLATING.


Andy.

[davieo45]

Ok, thank you for your insight. It helps to know that I shouldn't need to bias the amp. After reading some reviews, I decided to order a matched quad of JJ's. Once they get here ill plop them in and see what I got. I appreciate all the help fellas especially since im not very electronically inclined

[GMan]

Does the TH30C come brand new with any JJ's in it, the reason I ask is because I bought mine used and it had JJ's for all four of the power tubes and one in V2, the other four were china.
Has anyone else found JJ's in there's when purchased new? Thanks.

[davieo45]

After taking the old ones out, I noticed that mine had JJ's in the output section as well. I didn't take a look at the preamps though. And I don't know if they come new, but mine is used so idk if that's why.

[cobrain]

Hey!
Did you swap the tubes? Have you noticed some improvements?
However my TH30 (that I bought used) has JJ's tubes (pre and power) but since I bought it used I don't know if the former owner has made a tube swap.