Anyone tried solid state valves yet?

martinw

jaygtr said:

Slightly off topic, but do valves deteriorate over time if left unused in a box in good conditions , or will 50 year old unused valves be as good now as back then?

Good point. The key issue is vacuum, or leakage, but also there might be some decomposition of materials within the envelope. No vacuum is perfect, and nothing is 100% leak tight, so it might be that the normal deterioration of materials is slowed down, but not halted.

I've got 50 year old valves that still work fine, but I don't know how they compare to how they were new. There's no way to measure how much vacuum they've lost, so the rate is unknown.

They might last another 50 years, who knows? Maybe the rate of deterioration is so slow, they'll last for several hundred years? Vacuum is an amazing thing when it comes to preservation. (That's backwards, I know!)

Wouldn't it be funny if valves turn out to outlast semiconductor devices?

Phil_aka_Pip

They would in case of a nuclear war

jaygtr

So is now the time to start storing some valves for future use perhaps, before they become stupidly expensive ?

ThePrettyDamned

jaygtr;12754" said:

So is now the time to start storing some valves for future use perhaps, before they become stupidly expensive ?

Nah, that was the early 90s when people were genuinely convinced they were on their way out. Probably happened in the 80s too, but that's before my time sadly! My dad saw music shops throwing valves in skips, though.

ddlooping

Another interesting Retro Channel product, a power amp...

ICBM

martinw said:

Good point. The key issue is vacuum, or leakage, but also there might be some decomposition of materials within the envelope. No vacuum is perfect, and nothing is 100% leak tight, so it might be that the normal deterioration of materials is slowed down, but not halted.

I've got 50 year old valves that still work fine, but I don't know how they compare to how they were new. There's no way to measure how much vacuum they've lost, so the rate is unknown.

They might last another 50 years, who knows? Maybe the rate of deterioration is so slow, they'll last for several hundred years? Vacuum is an amazing thing when it comes to preservation. (That's backwards, I know!)

Wouldn't it be funny if valves turn out to outlast semiconductor devices?

The vacuum should remain as good as new for as long as there's any getter metal left, surely?

So the life expectancy in storage is really the length of time it takes for the getter to be completely used up, or the percentage of it left relative to new, depending on how you look at it.

Have you come across old MOSFETs just failing for no apparent reason? - not shorted, just don't conduct any more. I seem to have, although I can't say how they might have been abused.

Grumpyrocker

That sounds really good - or perhaps I hope it does without all that reverb and delay.

Van_Hayden

Kind of can't help but think if there's a couple of toroidal transformers in there it'll be so heavy I might as well carry a valve amp. Nice idea, need to try one though....

digitalscream

Van_Hayden said:

Kind of can't help but think if there's a couple of toroidal transformers in there it'll be so heavy I might as well carry a valve amp. Nice idea, need to try one though....

Not at all - toroidal transformers are usually lighter than the big hulking bits of metal you get in most valve amps. I had an R&R SOLO amp (basically a two-channel 50W SLO-alike in a 1U chassis) and it weighed a whole 4kg. Sounded ace, too...part of me wishes I hadn't sold it, actually....

ddlooping

Van_Hayden said:

Kind of can't help but think if there's a couple of toroidal transformers in there it'll be so heavy I might as well carry a valve amp. Nice idea, need to try one though....

22 pounds (~10Kg)
http://www.retro-channel.com/ProductDetails.asp?ProductCode=PA1

Van_Hayden

Granted if its only developing 50w - I've carried too many big PA amps....

Toroidal transformers aren't that much lighter than decent EI trannys with M-6 lams when you factor in how many solid state watts you need to compete with the perceived power of 100w of valve power into a 16ohm cab.

digitalscream

Van_Hayden said:

Granted if its only developing 50w - I've carried too many big PA amps....

Toroidal transformers aren't that much lighter than decent EI trannys with M-6 lams when you factor in how many solid state watts you need to compete with the perceived power of 100w of valve power into a 16ohm cab.

I'm pretty sure that the whole "solid state amps need more power to generate the same volume as a valve amp" thing is largely to do with the fact that generally solid state amps are built to a cost and are therefore direct-coupled. A well-designed solid state amp using output transformers would likely generate as much volume as a valve amp.

At least, that's what I've read...

ICBM

digitalscream said:

I'm pretty sure that the whole "solid state amps need more power to generate the same volume as a valve amp" thing is largely to do with the fact that generally solid state amps are built to a cost and are therefore direct-coupled. A well-designed solid state amp using output transformers would likely generate as much volume as a valve amp.

At least, that's what I've read...

No, there's quite a lot more to it than that. The transformer is a factor in the sound and possibly a little in the perceived volume, but you can't make a solid-state amp as loud as a valve one just by using an output transformer.

There are a lot of different factors involved, and some are very hard to duplicate with solid-state.

In fact, it will be interesting to see whether a valve amp with solid-state plug-ins is as loud as the same amp with real valves.

martinw

ICBM said:

The vacuum should remain as good as new for as long as there's any getter metal left, surely?

So the life expectancy in storage is really the length of time it takes for the getter to be completely used up, or the percentage of it left relative to new, depending on how you look at it.

 

Yes, seems fair. The getter material is only designed to mop up reactive gases that desorb from the envelope walls after the valve is sealed. My feeling, having worked with getter pumps, is that a small mount of flashed getter won't cope with much leakage of air in that way. Most valves would seem to have excellent vacuum...I think any with much in the way of a leak would soon saturate the getter.

ICBM said:

Have you come across old MOSFETs just failing for no apparent reason? - not shorted, just don't conduct any more. I seem to have, although I can't say how they might have been abused.

I can't say I have, although I read an article years ago about decomposition of SS devices at the junctions, so it's possible there might be a lifespan on these things.

digitalscream

ICBM said:

No, there's quite a lot more to it than that. The transformer is a factor in the sound and possibly a little in the perceived volume, but you can't make a solid-state amp as loud as a valve one just by using an output transformer.

There are a lot of different factors involved, and some are very hard to duplicate with solid-state.

In fact, it will be interesting to see whether a valve amp with solid-state plug-ins is as loud as the same amp with real valves.

Well, I presumed it wouldn't be quite that simple Hence the "well-designed" bit...however, what I've read does seem to indicate that transformer-based coupling is more efficient than direct-coupling when used with a reactive load like a normal speaker. Does that seem accurate to you?

ICBM

It's not more efficient, no - in fact it's less efficient since there are losses through the transformer. But it does change the damping factor, which is one of the components in perceived volume vs actual measured power output.

Still, fitting a solid-state amp with an OT - there are a few - doesn't do as much as you might think. It is part of the answer, but not the majority of it.

Van_Hayden

ddlooping;12860" said:

Van_Hayden said:

22 pounds (~10Kg)

http://www.retro-channel.com/ProductDetails.asp?ProductCode=PA1

Well @digitalscream I may well stand corrected. I'd like to try one against the Matrix I've got in the AxeFX rig. The main thing I like about the Matrix is size and weight, tone wise I'm not quite sure yet

ragingben

AMT valves available now - 12ax7's for $40 USD each, in quantities of 4.

http://eshop.amtelectronics.com/accessories/12ax7ws-warmstone-12ax7-tubes-solid-state-equivalents.html

Thomann have them too

http://www.thomann.de/gb/amt_warm_stone_12ax7_ws.htm

ICBM

ragingben said:

AMT valves available now - 12ax7's for $40 USD each, in quantities of 4.

http://eshop.amtelectronics.com/accessories/12ax7ws-warmstone-12ax7-tubes-solid-state-equivalents.html

Good to see the specs - that ratings are actually about 50% higher than those of a real 12AX7. Particularly good to see they've thought about the critical one in some amps - the cathode-to-heater voltage rating, which is 250V for a 12AX7, but some (particularly Russian) valves fail to meet it properly which can cause trouble.

ragingben said:

Thomann have them too 

http://www.thomann.de/gb/amt_warm_stone_12ax7_ws.htm

30th of September before they're available through Thomann by the look of it.

Cirrus

They look cool.