HT-1 Tube Replacement

Discussion - HT-1 amplifiers
Posts: 9
Joined: Tue Jul 05, 2011 12:00 am
Location: Norway

Fri Aug 19, 2011 6:54 am

Finally got around to replace the tubes. Interesting. :)

First impressions:
Cleans are improved with more clarity and harmonics. The bass response seems more powerful. Crunch and OD does, however, seem less aggressive on the border to tame. Adding a tubescreamer helps.

I think I'll play around a bit with these tubes for a while to get used to them and find the sweet spot settings. But to me it seems like the Golden Dragon 12ax7 preamp tube is an improvement over the original Sovtek tube, while I have my doubts about the Golden Dragon 12au7 power tube. I think I'll probably switch back to the original TAD tube.

From now on I think it is wise to switch only one tube at the time. This gives more control when it comes to what tube causes what changes in sound.

This is fun!

And BTW, when the HT-1R combo back plate with the amp is out (thanx to the forum for the tip about the two screws in the handle), changing tubes is really, really easy. Just remember to unplug and cool down the amp before opening it and changing the tubes.

Posts: 9
Joined: Tue Jul 05, 2011 12:00 am
Location: Norway

Fri Aug 19, 2011 6:27 pm

Decided I didn't like the crunch on the clean channel as well as before, so I decided to swap back to the original TAD 12au7 tube.

Better: the cool aggressiveness is back, but at the cost of a little less bass power than the Golden Dragon.

I've still got the Golden Dragon 12ax7 preamp tube in it, and the clarity and rich harmonics are still there, and the harmonics stays for the OD too. I love it. It feels like the little amp has come a bit more to life.

Now the next brand up is Tung-Sol... But I am going to wait a bit before changing tubes. Want to get to know the Golden Dragon 12ax7 a bit better first.

Posts: 1
Joined: Fri Oct 07, 2011 12:00 am

Fri Oct 07, 2011 5:43 am

Hello All this is my first post on this forum.

What I am understanding is when the output tube is changed in the HT 1R no biasing is required. Is this because the output tube is in reality a preamp tube functioning as an output tube? Or is it due to the cathode bias of the amp?

Maybe a function of both but sure seems like a big selling point, among others for this amp.

Thanks in advance for any input!

Posts: 1
Joined: Fri Nov 04, 2011 1:00 am

Fri Nov 04, 2011 4:19 pm

I have the HT-1RH and I'm looking at taming the OD channel (take it from heavy metal to good ol classic rock) and maybe give the clear channel a little more clarity. I see the TheTubestore has a nice table that shows tubes gain levels . Anyone have a tube recommendations? I have replaced tubes on my Fender SuperChamp but info on the Blackstar is rather limited.


Posts: 8
Joined: Fri Dec 16, 2011 1:00 am

Fri Dec 16, 2011 9:36 pm

I have the HT-1 RH head, and am wondering that once I have the back of it off is it obvious which valve is which as I can't find a layout schematic anywhere ?

Tracer Tong
Posts: 6
Joined: Sun Nov 20, 2011 1:00 am

Tue Dec 20, 2011 9:28 pm

Hey everybody, I've been playing my HT-1R a bit more than usual lately and I find myself with a question.

There are parts in the volume and gain knobs travel that give way more change than other parts. What I mean is, you can turn up the gain for a while and get only a little difference, and then you hit a spot where all of a sudden it takes off. My questions are as follows: is this normal? If I replaced one (or both) of the tubes would the adjustment be more linear?

I ask because it seems like there would be some really nice tones right in that area where a little knob movement makes a big gain movement.

Thanks for your answers!

Posts: 8
Joined: Fri Dec 16, 2011 1:00 am

Tue Dec 20, 2011 9:45 pm

Hi - I have ony had my HT1-RH for a few days but mine does the same, especially the Gain on the clean channel - somewhere about 1 o'clock to 2 o'clock it takes off.

I haven't changed valves yet though so can't help with that bit of your question.

Posts: 1
Joined: Wed Oct 08, 2014 2:51 pm

Wed Oct 08, 2014 2:53 pm

Hey guys i have a blackstar ht1 r
but i want to know how to change the tubes
i cant get it open

Ty for help

User avatar
Posts: 100
Joined: Sun May 20, 2012 12:00 am
Location: USA

Fri Oct 10, 2014 10:22 pm

To get at the tubes in the HT1R combo I remove the screws holding the back on to the combo. Then I loosen the two rear handles screws until the chasis can be gently lifted out and rested on the back's edges. Be gentle when removing either or both of the tubes. Turn the retainer clips down and gently twist back and forth while gently lifting up on the tube to remove it. Make sure, of course, that the amp's power cord is not in the wall outlet and remove it from the the back of the amp before attempting any of the foregoing.

With respect to the gain pot. It is a 220K graphic taper which might explain the sudden jump in it's effect when rotated to about 1:00'o'clock. I researched what a graphic taper is and the description that I found chacterizes the taper as a "reverse audio taper for the first half of its rotation and normal audio taper for the remaining half". It seems to make sense although I know little about electronics or pots.

I know that the original gain pot on mine became scratchy and my tech put it a new one with the wrong taper, but the correct value and it threw more gain at the beginning of the pot's rotation, thus rendering it almost unuseable. When I found a new gain pot with the correct taper and had the tech put that in, it restored the normal taper so that once again there is a jump in it's effect at about the same place on its rotation.

The HT1 has a goodly amount of gain on tap, so before swapping tubes try lowering the gain pot to 10 or 11 o'clock and adjust the volume pot upwards and see what the result may be.....on the amp's gain channel. Once I reached an acceptable setting, I wrote it down for future reference. I did the same for the clean channel.

The clean channel sounds decent and "Bassman" like with the volume about maxed, the gain at that 1 o'clock spot and the ISF adjusted to taste. With a Les Paul you should be able get useable tones with the guitar's volumes on something far less than 10. I hope this helps a few owners of this gem of a practice amp.


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