Official Blackstaramps Forum

Hi there,
I have a ht-5h that I have been using daily for the last 7 months, this morning I plugged in and the sound was gone unless I turn the amp all the way up, then I can hear it but its very distorted and quiet, this is the same for the gain channel also. If I plug headphones into the headphone jack it seems normal but I tried a old 8 ohm external cab I had laying around into the headphone jack and the sound was the same as the external cab I use normally. What could this be? Tubes need changing?

Thanks for your help this is very frustrating

James

The headphone/emulated out is taken from the preamp and the power amp isn't involved. So it sounds like it could be the power tube.

The power tube should be an Electro‑Harmonix 12BH7 (at least that's what mine has). If you put the same brand in, you shouldn't have to re-bias it...although it wouldn't hurt. The new tube should cost around $15 to $20 USD.

The headphone jack is not meant for a speaker, it should sound bad if you plug a speaker into the headphone jack. Did you try the other speaker into the amp speaker jack?

thephantum wrote: ↑

Fri Mar 07, 2014 11:02 pm

The headphone/emulated out is taken from the preamp and the power amp isn't involved. So it sounds like it could be the power tube.

The power tube should be an Electro‑Harmonix 12BH7 (at least that's what mine has). If you put the same brand in, you shouldn't have to re-bias it...although it wouldn't hurt. The new tube should cost around $15 to $20 USD.

You are right, its the power tube issue. I have purchased the power tube from ampvalves onilne store that they recommend a tube set for HT5r.
But I am curious about should I need to re-bias the amp?

If not re-biasing I placed the new tube, the problem will be fixed or same issue will remains?

Please give some advise how to re-bias the amp