HT-1 Tube Replacement

Discussion - HT-1 amplifiers
sizzlingbadger
Posts: 100
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Location: New Zealand

Tue Jul 05, 2011 9:18 pm

As far as I can tell the Mullard is the exact same tube as the Sovtek LPS, just has a different label. The long plates in these tubes can make them microphonic in combo's but I doubt thats an issue in small amp like this.

mordacain
Posts: 17
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Location: SC's dirty armpit

Tue Jul 05, 2011 9:27 pm

sizzlingbadger wrote:As far as I can tell the Mullard is the exact same tube as the Sovtek LPS, just has a different label. The long plates in these tubes can make them microphonic in combo's.
Incorrect. The Mullard reissues I've purchased recently are all short plate models. Sovtek manufactures multiple varieties of both long plat and short plate AX7s. the ones that come stock in the Blackstar products are all short plate. They are never micro-phonic unless bad, they just have a very grainy gain structure (that some people like). Personally I like the clearer gain of the mullard. The Tung-Sols introduce higher overall gain and are good for aggressive, yet tight hi-gain applications. I've not tried a higain spec'd JJ ECC83 gold in this amp but I imagine it would be a very nice middle ground between the Sovtek's graininess and the Mullard's smoothness. In my experience, JJ's overall tend to be very smooth.

sizzlingbadger
Posts: 100
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Location: New Zealand

Tue Jul 05, 2011 9:41 pm

Well I guess the Mullard re-issues are just using whatever is available and re-labeling them. This happens a lot these days. I have a Mullard and LPS and they are exactly the same in every way.

mordacain
Posts: 17
Joined: Tue Mar 22, 2011 1:00 am
Location: SC's dirty armpit

Tue Jul 05, 2011 9:51 pm

sizzlingbadger wrote:Well I guess the Mullard re-issues are just using whatever is available and re-labeling them. This happens a lot these days. I have a Mullard and LPS and they are exactly the same in every way.
I don't see how you can tell they are the same without disassembling them and testing the composition of the materials...

The New Sensor company makes Sovtek, Tung Sol (reissue), Mullard Reissue, Gold Lion, Electro Harmonix. They're all made at the same factory. The exterior designs are all relatively similar, the interior structure are what are different, and only loosely different at that. The only difference between the Sovtek and Mullard shortplates is the plate construction; just looking at the tubes and thinking they are similar won't tell you anything about the tube's structure itself.

What is important is the tonal difference. I've got roughly 25 different preamps tubes of varying makes. Some are NOS some are just plain old and others are completely new construction. They all have subtle differences, even the the 4 Sovtek's I have (WLXT+ if I recall properly off the top of my head) sound different tube to tube.

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

Tue Jul 05, 2011 10:14 pm

mordacain wrote: 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.
So I'll have to expect to change power tubes often?

I think I'll take it to the dealer this time, and if it actually turns out to be a power tube failure, I guess I should buy some extras and learn how to change them myself. Changing and trying out different tubes is some of the fun with a tube amp too... :)

mordacain
Posts: 17
Joined: Tue Mar 22, 2011 1:00 am
Location: SC's dirty armpit

Tue Jul 05, 2011 10:48 pm

sarge wrote:
mordacain wrote: 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.
So I'll have to expect to change power tubes often?

I think I'll take it to the dealer this time, and if it actually turns out to be a power tube failure, I guess I should buy some extras and learn how to change them myself. Changing and trying out different tubes is some of the fun with a tube amp too... :)
Yea, as far as I know, biasing will not be needed for the HT1 based on the tube type, so that simplifies things quite a bit.

sarge
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Location: Norway

Tue Jul 05, 2011 11:35 pm

OK. Thanks again! :)

sizzlingbadger
Posts: 100
Joined: Wed Oct 13, 2010 12:00 am
Location: New Zealand

Wed Jul 06, 2011 10:49 pm

mordacain wrote:
sizzlingbadger wrote:Well I guess the Mullard re-issues are just using whatever is available and re-labeling them. This happens a lot these days. I have a Mullard and LPS and they are exactly the same in every way.
I don't see how you can tell they are the same without disassembling them and testing the composition of the materials...

The New Sensor company makes Sovtek, Tung Sol (reissue), Mullard Reissue, Gold Lion, Electro Harmonix. They're all made at the same factory. The exterior designs are all relatively similar, the interior structure are what are different, and only loosely different at that. The only difference between the Sovtek and Mullard shortplates is the plate construction; just looking at the tubes and thinking they are similar won't tell you anything about the tube's structure itself.

What is important is the tonal difference. I've got roughly 25 different preamps tubes of varying makes. Some are NOS some are just plain old and others are completely new construction. They all have subtle differences, even the the 4 Sovtek's I have (WLXT+ if I recall properly off the top of my head) sound different tube to tube.
My 25+ years of electronic design experience, my ears, my eyes and my Mark IV Avo valve tester tell me other wise ....

All long plate tubes are prone to microphonics in a combo amp, this is common knowledge. This is why Blackstar choose short plate Sovteks, they don't sound great but they are very robust and very cheap.

However... its good to know that my Mullard re-issue is probably just a re-label though as I can try and get a proper short plate one to try out. The re-issues are not the same as the original tubes, they are produced in a way to try and get some of the characteristics of the original designs but due to the restrictions on the chemicals these days they can't make them the same. A lot of tubes get re-labeled when supplies are short this has been the case for many years and is nothing new.

The New Sensor Co. don't make tubes, they are a marketing company. A good list of manufacturers can be found here http://www.vacuumtube.com/mfg.htm

I should have been more careful in my original post and stated the Mullard tube I have is the same as the LPS but not all Mullard tubes are - apologies for any confusion.

trewblue
Posts: 3
Joined: Sun Aug 07, 2011 12:00 am
Location: just about a moonlight mile on down the road

Tue Aug 09, 2011 2:35 am

Just won a HT-1 at a local music store. I changed out the preamp tube and put in a Mullard. Very happy with the results!! I'm running it into a 1X12 custom cab with a Altec-Lansing speaker in it. I also have a Tung-Sol and will give that one a try in a couple of weeks. I also have a Vox AC4 and the HT-1 is a real nice addition.

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

Tue Aug 09, 2011 9:14 pm

Got hold of a couple of Golden Dragons. These are tubes modelled after Mullard NOS tubes. But at a cheaper price.

I know these tubes are not necessarily the best for guitar amps, but then neither should the Mullards be, and a lot of people seem satisfied with them.

What I want is to improve the clean sound, if possible. We'll see... ;)

Wish me luck. It will be my first tube replacement on a Blackstar. ;)

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