Possibly buying a Blackstar HT5 Head, issues/advice needed..

ICBM

ecc83 said:

The 12BH7s seemed to live long as well  but naturally get a much harder life. The fact that the circuit has been 'hacked' by at least 2 others means the 12BH7 could get short supply, bound to get expensive! Might be an idea to get one in now!

To be honest this is something that would concern me a bit in the long term - if the 12BH7 goes back out of production it may be difficult to get in the future. I've never been keen on designing for uncommon valve types, having used original Fender Super Champs which take a 6C10 preamp valve...

I have wondered if it would be possible to replace it with a pair of ECC82s on a daughter board - a very common valve - as a possible long-term solution if the BH ever becomes unavailable.

bloodandtears

@ecc83 ;  I want use a midi switcher with this.. can you tell me if the footswitch is momentary or latching?? some of the options (NUX) are troublesome with momentary it seems which would force me down the Voodoo Labs route I believe..

kennedydream1980

The mk1 model has less headroom on the clean channel and less gain on the overdrive.

The Mk2 version obviously has reverb, has a ton more headroom on the clean channel, and has a tone control exclusively for the clean channel, leaving the 3 band EQ and ISF control exclusively for the overdrive channel. The OD channel has ridiculous amounts of gain available if you want it.

Both versions can be very loud wound up through an efficient speaker cab (I gig with mine regularly) 

But they also sound great at bedroom volumes.

ecc83

B&T .The FX loop debacle was only on a few VERY early MK ones. There was a fair number of mods for that TBH but then it was a pretty radical amplifier at the time (been ripped now of course!) Should you get hold of such an old model I really cannot say what Blackstar would tell you but I like to think they would be sympathetic.

The switch is latching. I discovered that this is contrary to most other FS logic and actually did some 'back of envelope' drawings to make a momentary pulse into a hard switch. Easy 'on'.. Off again not so easy. Our man Sporky might have some ideas?

Dave.

Danny1969

Dave, it's not latching on either on mine, momentary push to make switches channels 

DJH83004

Wasn't aware of any talk about the 12BH7 going out of production, I know EH are still manufacturing and so are TAD in China, agree the production must be in very low volumes. The last one I changed (outside of a HT5) was a DSL 5, not sure where else they crop up ( can't see there being much demand for TV frame oscillators these days !)

bloodandtears

Momentary or latching?? Which is it? Or does it differ between MK1 and MK2?

ecc83

bloodandtears said:

Momentary or latching?? Which is it? Or does it differ between MK1 and MK2?

Sorry, as I said, been out of the biz for a while now (and had health issues) I would put money on the Mk1 being latching because the next amps were the S1s and they weren't! I don't have a Five here, have a 20 and I am sure that is latching but will check tomm'

Now, the HT pedals FELT like they latched but didn't and were 2 pole C/Over!

Dave.

ecc83

DJH83004 said:

Wasn't aware of any talk about the 12BH7 going out of production, I know EH are still manufacturing and so are TAD in China, agree the production must be in very low volumes. The last one I changed (outside of a HT5) was a DSL 5, not sure where else they crop up ( can't see there being much demand for TV frame oscillators these days !)

Doesn't the Ampeg SVT use a 12BH7?

Dave.

ecc83

ICBM. Re a pair of ECC82 as a replacement? Certainly could handle the power but Va is specced as 300V max, but then when did guitar amp designers care greatly about paper specs?!

More of an issue (and I have not looked at the curves) is whether a pair of 82s will bias correctly with the available bias voltage, remember, two valve in parallel give twice the gm.  I doubt the OPT will be the right ratio and that could change the sound of the amp drastically. Never know IC you might like that!

Of course the very BEST solution would be for the major USERS of valves around the world to get together and agree to fund the permanent production of decent quality products. For the gitamp industry that would only be about 10 types tops?  (I read somewhere that the HI-FI industry buys many more valves than guitar amp makers?)

Dave.

ICBM

DJH83004 said:

Wasn't aware of any talk about the 12BH7 going out of production, I know EH are still manufacturing and so are TAD in China, agree the production must be in very low volumes. The last one I changed (outside of a HT5) was a DSL 5, not sure where else they crop up ( can't see there being much demand for TV frame oscillators these days !)

Probably not imminently, but if there's going to be a reduction in valve manufacturing at any point in the future, the small-numbers types will be the first to go - so in my opinion it's unwise to design a new amp around them when there are other options.

ecc83 said:

Doesn't the Ampeg SVT use a 12BH7?

Not any more - 12AU7s in all the new ones. Of course there are still quite a lot of old ones around.

ecc83 said:

Of course the very BEST solution would be for the major USERS of valves around the world to get together and agree to fund the permanent production of decent quality products. For the gitamp industry that would only be about 10 types tops?

There was a time in the early 90s when it looked like it would only be three types - 12AX7, EL84 and 6L6/5881. Even Marshall changed to using 5881s for a couple of years because a reliable supply of decent EL34s wasn't available.

So if the types are 12AX7, 12AT7 (by far the two most common preamp valves), 12AU7 (probably, although still not used much now), EL84, 6L6, EL34, 6V6, 6550, KT88 (the most common power valve types in probable descending order)… that would leave the 12BH7 as no. 10 at best - even if you ignore rectifiers, which I know you would like to but are definitely used in much higher numbers.

So any reduction in demand would be likely to see it go first I would think.

ecc83 said:

(I read somewhere that the HI-FI industry buys many more valves than guitar amp makers?)

I read that somewhere too, but I find it very hard to believe. The volumes of guitar amps being made which still use valves have to be far higher than the tiny market for valve hi-fi, and as we know guitar amps usually thrash the valves so they only last a short time.

Danny1969

bloodandtears said:

Momentary or latching?? Which is it? Or does it differ between MK1 and MK2?

MK1 is non latching push to make to switch channels 

ecc83

Maybe the hi fi boys BUY a lot but because they are mostly ***t they only use 5% of them? Then sell the remainder to us!

I found only 10% of a batch of 50 ECC83s were good enough for the A30 front end but then I am a fussy, 'hi fi' bastd!

10% of the rest were hummy as **** as a PI which is one reason why subsequent designs all had DC heated pre amp valves. I have no hard evidence but it seemed to me that a regulated, DC heater supply made the triodes last practically forever?

Dave.

ICBM

ecc83 said:

Maybe the hi fi boys BUY a lot but because they are mostly ***t they only use 5% of them? Then sell the remainder to us!

That did occur to me as well .

ennspek

Arktik83 said:

It's well documented that HT5's aren't actually 5 watts more like 8 - 10 watts I heard?  They are, in my experience, Loud.  Even when on 1.  Not massively ear splitting volumes but maybe a little too loud for a small flat.

With that said the only known fault I had with one was the foot-switch sometimes wouldn't activate the overdrive channel but I'm sure this was just a loose connection somewhere rather than an actual factory flaw.

Actually now that you mention it I have an HT5r combo and the footswitch can be a wee bit temperamental.

ecc83

ennspek said:

Arktik83 said:

It's well documented that HT5's aren't actually 5 watts more like 8 - 10 watts I heard?  They are, in my experience, Loud.  Even when on 1.  Not massively ear splitting volumes but maybe a little too loud for a small flat.

With that said the only known fault I had with one was the foot-switch sometimes wouldn't activate the overdrive channel but I'm sure this was just a loose connection somewhere rather than an actual factory flaw.

Actually now that you mention it I have an HT5r combo and the footswitch can be a wee bit temperamental.

They actually start to clip at a shade under 5W but such a scope test is never that accurate and is a mk1

 eyeball call*.

If you continue to press them they really start to square off at around 10W . These tests were all done at a measured 230V in. Most of us get 240ish most of the time so you would get a little bit more than the bench figures.

I well recall that one of the criticisms (amongst a LOT of love!) of the HT-5 was 'lack of clean power' Could these people not read?

*Only true way to test amp Pout IMHO is 'X watts into R load for Y distortion' A figure of 10% THD would seem right for guitar amplifiers?

Dave.