HT-1 Tube Replacement

[Relay]

Found a website that gives a couple of alternatives to the stock HT-1 tubes.

http://thetubestore.com/blackstar-ht-1.html

It claims that the HT-1 has cathode bias which means that the amp wont require re-biasing when changing tubes, which is good I guess

Might end up doing a pull-apart guide for the combo eventually when I get round to swapping mine.

[Superchampable]

Ya show us some gut shots too. I know blackstars have a ton of internals but I wonder if the ht-1 is more mod friendly.
I think id be hesitant to change tubes with out blackstars approval. Wonder why they dont mention its cathode biased?
Theyd sell more amps if it is.

[KKND]

I think the reason Blackstar doesn't want to c=share the internal schematics/specs/info is the secret of the trade!!! good catch btw, awesome site !

[Christopher]

Did you guys figure this one out? I bought new tubes, but trying to remove back cover of amp proved very difficult. I really want to change them, as my HT-1 has a somewhat too-loud-for-recording buzz going on, that I believe comes from the tubes. Do you guys experience a loud hiss?

Thanks,

Christopher

[mosesve]

I can confirm a little bit of hiss at the recording output and I´m also trying to figure out where it comes from.
But I´m also into changing tubes of my two ht-1r, cause they sound really different...
Perhaps a matched set of 5751's for the preamp and a matched set of power amp tubes will decrease the gain a little bit and give them more similarity.
The first one I bought is just about half as loud as the second one, so it is not so easy to match them both for a nice stereo-setup.

Greetz,

- mo -

[mordacain]

Hey guys, I'm new here but I believe I can address some of these questions.

I currently have a Mullard reissue in my little HT1 Combo.

To access the tubes you need to remove all of the screws on the back panel and the two rear-most handle screws. The handle screws are actually what support the weight of the amp PCB and tubes.

My experience with the TAD tubes caused me to leave the stock TAD power tube (I quite like them) but I tried various NOS long plate and JJ, Tung-Sol and a Mullard Reissue short plate in the 12AX7 pre slot. The Mullard was the clear winner and the Tung-Sol runnerup. I like heavy a good balance of clean, low noise with clarity in higain applications.

[Relay]

Finally did it.

Went with the Tung-sol in the preamp and a JJ. The clarity is amazing, distortion that doesn't just blob along. More 'headroom' on the clean channel, and the ISF knob goes to at least 12 now in either direction, seems to be more volume too.

Although i have noticed that there is more noise when not playing than I remember (played the amp about a week ago, guitar was in getting service). Will try putting the TAD back in later on to see if that changes it, but at the moment i can live with it.

Thanks mordacain for the tip about the screws in the handle, was super easy to open up. Might give the mullard a try too later on.

[mordacain]

Finally did it.

Went with the Tung-sol in the preamp and a JJ. The clarity is amazing, distortion that doesn't just blob along. More 'headroom' on the clean channel, and the ISF knob goes to at least 12 now in either direction, seems to be more volume too.

Although i have noticed that there is more noise when not playing than I remember (played the amp about a week ago, guitar was in getting service). Will try putting the TAD back in later on to see if that changes it, but at the moment i can live with it.

Thanks mordacain for the tip about the screws in the handle, was super easy to open up. Might give the mullard a try too later on.

Yea, the Mullard is super-nice in every amp I've thrown in it. I was all about Tung=Sol (have 4 of them currently) before giving the Mullard a go. They're very similar, but the Mullard is a touch clear, a bit more articulate which makes the full gain range very usable.

[sarge]

Great info. I've had my HT-1R combo for about 5 months, and recently the sound lost its full tone, has less dynamic punch (even within the constraints of a 1 watt amp) and on OD it seems more harshly distorted and less overdriven.

Is this a typical tube problem, you think? Is it even possible that it can be the speaker element?
If it is the tube, what can be done to verify if its the preamp tube or the power tube?

I have cranked the volume and/or played it with a tubescreamer clone pedal about an hour each day. Would the tube be worn out after only 5 months with that kind of use?

I guess opening the amp myself to change to another tube will be a violation of warranty terms?

[mordacain]

Great info. I've had my HT-1R combo for about 5 months, and recently the sound lost its full tone, has less dynamic punch (even within the constraints of a 1 watt amp) and on OD it seems more harshly distorted and less overdriven.

Is this a typical tube problem, you think? Is it even possible that it can be the speaker element?
If it is the tube, what can be done to verify if its the preamp tube or the power tube?

I have cranked the volume and/or played it with a tubescreamer clone pedal about an hour each day. Would the tube be worn out after only 5 months with that kind of use?

I guess opening the amp myself to change to another tube will be a violation of warranty terms?

This sounds like an output tube to be honest. Preamp tubes typically last for a long time. Since Blackstar is using one as an output tube, I would expect its life span to drop pretty significantly. Personally I would get in communication with Blackstar first, but I don't think tube replacement voids the warranty if it is done by a qualified tech.