JJ Valves?

robgilmo

Firstly, do different brands sound different? What is the general craic with JJ valves? Also I have heard mention of NOS? Are they new old stock? What would you suggest as a replacement to get as close to original in a Peavey Deuce?

ICBM

Yes, different brands sound different - some more than others.

JJ valves are reliable, robust modern valves. They tend to have a darker, more midrangy tone that some people like and some people don't. (One of the more distinctive, hence divisive.) More noticeable in preamp valves than power valves.

NOS means New Old Stock, yes. It *should* mean strictly that - unused (apart from testing) old-production valves from the original top-quality Western manufacturers. Unfortunately some people use it to mean any old (used) old-production valve, and some use it to mean unused *modern* valves from the first generation of Chinese and Eastern-European production, just because some of those are now more than 20 years old... it's a bit like 'vintage' guitars .

Getting close to original in a Peavey Deuce is going to be difficult, and expensive. The original Peavey 'Super 6' valves were made by Philips/Sylvania in the US, which are widely regarded as some of the best 6L6s ever made. They (all Sylvania 6L6s) are now in very short supply if you can find them at all - almost extinct as NOS - and will cost you a small fortune.

From a sound point of view the closest modern valves are probably the TAD 'RCA/GE' (the other two big US manufacturers) 6L6GCs.

http://www.tubeampdoctor.com/en/shop_TAD_Premium_Tubes_TAD_Power_Tubes_SELECTED/6L6GC_STR_RCA_Style_black_plate_TAD_PREMIUM_Selected_2824

Does that help?

robgilmo

It does, thankyou,  I shall keep my eyes peeled for some Sylvanias , those TAD valves dont seem too expensive for what they are , is the difference in valves subtle or night and day? I have two new JJ's and two old Sovtek valves in there at the moment, the Sovteks have 02 04 written on them, is that a manufacture date?

DJH83004

I genuinely don't think the choice of output valves will make a massive difference to the Deuce, I know IC is a Peavey man so take his advice on board, but unless you could get hold of a set of vintage RCA's (which do last forever!) I personally think JJs  or TADs are a good modern choice.      

jpfamps

I was going to try some of the TAD 6L6-STRs as an alternative to the JJ 6L6 (which is what we generally use).

Anyone have any views on these?

timmysoft

I’ve found all TADs to be really tough, I’ve not used the 6L6 but they have to be better than the JJ ones! 

jpfamps

timmysoft said:

I’ve found all TADs to be really tough, I’ve not used the 6L6 but they have to be better than the JJ ones! 

We've had good results with the JJ 6L6s; we installed over 100 into amps last year with no failures.

We now use the TAD EL34s which seem very robust.

We've seen several failed TAD 6V6s in amps that have come into the workshop, so these don't seem that robust given that we rarely seen 6V6 failures in other brands.

Chester

+ 1 in support of TAD's. Got 6L6's in my Carol Anns and an ElectraDyne at the moment, with excellent results. Also bombproof

Dominic

Okay.....VALVES ???
I understand that different circuits use different valves and that they have different bias, output and characteristics
I understand that they are handmade, quite fragile and that a small percentage are duff from the start
I understand that they can be tested and matched to pairs /quads etc
I am completely lost on the audible / User side of things
When it is said that a certain valve is better than another brand equivalent are we talking reliability, build quality or a truly discernible audio /guitar sound difference ?
Apparently there are only 3 companies left in the world that make them but brand them according to the company they supply
- is this true ?
What physical/audio difference makes some NOS any better?.......is it just Vintage Bullshit?
Is the Cryogenic treatment offered by Watford Valves simply Snake Oil or is there a logical basis for this extreme ?
What exactly makes an old Mullard more desirable in your Marshall than it's new equivalent.......could the player that swaps some over really hear a difference ?
I assume that there is some law of diminishing return and huge price differences
......Answers from the Tech Savvy/ Ampbuilders and Repairers or audiophiles please

Funkfingers

The old English-made Mullard valves were what would have been in the old Marshall amplifiers back in the day. Some people, desperate to EXACTLY recreate the sounds of yesteryear, feel it necessary to use EXACTLY the same valves as yesteryear. Followers of this belief system make zero allowance for the fact that the "as they would have been" valves will be run in aged, worn, drifting off-spec circuits. 

As Aspen Pitman of Groove Tubes says, the only real test is to plug in and play through them. If you don't like what you hear, change it. If you do like it, keep it.

Some of the claims made for Cryo treatment and other post-production processes is probably of far more relevance to hi-fi enthusiasts than Rock musicians. 

ICBM

Dominic said:

When it is said that a certain valve is better than another brand equivalent are we talking reliability, build quality or a truly discernible audio /guitar sound difference ?

Both.

Dominic said:

Apparently there are only 3 companies left in the world that make them but brand them according to the company they supply
- is this true ?

Yes - I think it's just three. New Sensor (Russia), JJ (Slovakia) and Shuguang (China).

Dominic said:

What physical/audio difference makes some NOS any better?.......is it just Vintage Bullshit?

No, not just bullshit - they really do sound different, most people think better. They were made to a higher quality standard than modern valves, because there were applications (military, avionics, scientific, medical equipment etc) which demanded it.

Dominic said:

Is the Cryogenic treatment offered by Watford Valves simply Snake Oil or is there a logical basis for this extreme ?

Snake oil, in my opinion.

Dominic said:

What exactly makes an old Mullard more desirable in your Marshall than it's new equivalent.......could the player that swaps some over really hear a difference ?

Yes.

Dominic said:

I assume that there is some law of diminishing return and huge price differences

Very much so - some brands, including Mullard and Telefunken, are very much more valuable than other NOS types, for very little justifiable reason in terms of quality. Telefunkens don't even sound that good in guitar amps really - they're valuable more because of the hi-fi market.

fandango

Dominic said:

Okay.....VALVES ???
I understand that different circuits use different valves and that they have different bias, output and characteristics
I understand that they are handmade, quite fragile and that a small percentage are duff from the start
I understand that they can be tested and matched to pairs /quads etc
I am completely lost on the audible / User side of things
When it is said that a certain valve is better than another brand equivalent are we talking reliability, build quality or a truly discernible audio /guitar sound difference ?
Apparently there are only 3 companies left in the world that make them but brand them according to the company they supply
- is this true ?
What physical/audio difference makes some NOS any better?.......is it just Vintage Bullshit?
Is the Cryogenic treatment offered by Watford Valves simply Snake Oil or is there a logical basis for this extreme ?
What exactly makes an old Mullard more desirable in your Marshall than it's new equivalent.......could the player that swaps some over really hear a difference ?
I assume that there is some law of diminishing return and huge price differences
......Answers from the Tech Savvy/ Ampbuilders and Repairers or audiophiles please

I second the questions. Brilliant post that encapsulates some of the thoughts that bounce around in my own mind.

jpfamps

As someone running a repair workshop, No 1 priority is reliability.

It really wouldn't do my business a lot of good to fit unreliable valves into amps.

Also we need to buy in reasonable bulk, maybe 20-50 pieces at a time so don't want to lumbered with a load of duff valves.

Re the JJ 6L6s, I've had pretty good results with these, but we are always looking into alternatives.

crunchman

On the cryo treatment, it's possible there is something to it.  For the record, my degree was in metallurgy/materials.  When this was discussed before, I googled and found some academic papers that showed that it did make changes to the microstructure of steel (or steels with enough carbon content to form Martensite anyway).  These changes can definitely affect the mechanical properties.  The changes will be permanent if the steel isn't reheated above 727C (austenite transformation temperature).  That would be glowing a nice red, so in a correctly biased amp a valve shouldn't reach those temperatures.

The papers didn't talk about any effect on electrical properties, although in a combo, with all the vibration, mechanical properties may have an effect.

I also don't know what material the internals of valves are made from, so this may or may not be relevant.  I couldn't find anything on metals/alloys other than steel.  If it happens in steel it could happen in other metals/alloys.  I just googled and there are martensite type of phases in some non-ferrous alloys so it's feasible that it could have a similar effect.

I'm not saying that there is an effect, but I wouldn't be confident to say that there is definitely no effect.

I bought a cryo valve once to try, but didn't like it in the amp I tried it in.  I didn't have another of the same valve non-cryo treated though, so it may have been that particular valve rather than the cryo treatment.

They only way to check for sure would be to get a decent sample size of the same type of valve cryo treated and non-cryo treated.  The cost of getting a decent sample, when I use my Kemper most of the time these days, means that it's not an experiment I'm going to perform.  At my current usage, I've probably got enough spare valves to last me a very long time.

jpfamps

crunchman said:

On the cryo treatment, it's possible there is something to it.  For the record, my degree was in metallurgy/materials.  When this was discussed before, I googled and found some academic papers that showed that it did make changes to the microstructure of steel (or steels with enough carbon content to form Martensite anyway).  These changes can definitely affect the mechanical properties.  The changes will be permanent if the steel isn't reheated above 727C (austenite transformation temperature).  That would be glowing a nice red, so in a correctly biased amp a valve shouldn't reach those temperatures.

The papers didn't talk about any effect on electrical properties, although in a combo, with all the vibration, mechanical properties may have an effect.

I also don't know what material the internals of valves are made from, so this may or may not be relevant.  I couldn't find anything on metals/alloys other than steel.  If it happens in steel it could happen in other metals/alloys.  I just googled and there are martensite type of phases in some non-ferrous alloys so it's feasible that it could have a similar effect.

I'm not saying that there is an effect, but I wouldn't be confident to say that there is definitely no effect.

I bought a cryo valve once to try, but didn't like it in the amp I tried it in.  I didn't have another of the same valve non-cryo treated though, so it may have been that particular valve rather than the cryo treatment.

They only way to check for sure would be to get a decent sample size of the same type of valve cryo treated and non-cryo treated.  The cost of getting a decent sample, when I use my Kemper most of the time these days, means that it's not an experiment I'm going to perform.  At my current usage, I've probably got enough spare valves to last me a very long time.

There is no question that cryo treatment can change the properties of materials.

There are a variety of materials used in valves,.

One consideration is the seal between the pins and the glass. 

The pins are made of an alloy Kovar that has identical thermal expansion properties to the glass envelope; this is to avoid problems with gas leaking into the enevelope due to differences in expansion and contraction due to heating / cooling in normal operation. Whether the relationship is maintained down to liquid nitrogen temperature is, as far as I am aware unknown.

As the valve contains a vacuum, the internal structures will have to cool largely due to conduction of heat through the pins (I expect there may be a smaller loss through radiation).

Regardless, there is of course no guarentee that any changes to the materials in the valve structure will be beneficial for "tone", and the cynical view would be that "hi-fi logic" is being applied, ie the more expensive and inconvenient solution must be the better one.

robgilmo

So , if heat doesnt travel through a vacuum, why does the glass get hot?

ICBM

robgilmo said:

So , if heat doesnt travel through a vacuum, why does the glass get hot?

Radiation.

thermionic

And conduction, but not through the vacuum of course.