Valve substitution question can an EF86 replace an EF804?

[john116]

Somewhere I read on a forum (maybe this one) where it was stated that an EF86 valve can replace an EF804. Is that correct? What I can find via google re valve specifications would seem to tell me this is incorrect?

[Nuvistor]

EF804 specification
https://frank.pocnet.net/sheets/128/e/EF804.pdf

Ef86 specification
http://www.r-type.org/pdfs/ef86.pdf

[Cobaltblue]

Originally Posted by john116

Somewhere I read on a forum (maybe this one) where it was stated that an EF86 valve can replace an EF804. Is that correct? What I can find via google re valve specifications would seem to tell me this is incorrect?

Maybe this thread?

https://www.vintage-radio.net/forum/...d.php?t=123169

Cheers

Mike T

[paulsherwin]

I think the pinouts are different so it's certainly not a plugin substitute. We don't see many EF804s in the UK - it seems to have been a Telefunken valve. I'm not sure Mullard/Philips ever made it.

[snowman_al]

The pin outs are different, so you cannot plug an EF86 into an EF804 position and vice versa.

There is a lot on the web about the pluses and minuses of the EF804 vs the EF86, so maybe people assume they are directly interchangeable, which they are not...

[john116]

Thanks all. I'll go shopping for a few EF804s in that case!

[Leon Crampin]

The EF804, EF86 and 6BR7 all have very similar characteristics, and would be electrically interchangeable in most applications.

However, they ALL have differing pinouts, and are therefore not equivalents.

The 6BR7 has a very similar pinout to the EF804 with only 3 fairly adjacent connections differing, so rewiring and using this type as a substitute should be straightforward.

On a practical note, I have found the 6BR7 to be superior to the EF86 in terms of noise, longer lasting and cheaper to buy. The EF804 and EF86 appear to have reached lunatic cult status in the market place and the 6BR7 has largely escaped this.

Leon.

[joebog1]

As I have mentioned before, Leon is absolutely correct with regards to noise, price and availability.
Do not forget the CV4006. Same pinout as 6BR7 but once again much lower noise.

Joe

[joebog1]

By lower noise I meant that the CV4006 is lower noise than 6BR7, or any of the aforementioned actually.

j.b.

[Richardgr]

Originally Posted by joebog1

By lower noise I meant that the CV4006 is lower noise than 6BR7, or any of the aforementioned actually..

Just quoting this small post, but I note that there are plenty of excellent NOS options for highly prized (and priced) tubes. The downside being that they may not be pin compatible or might have to be optimised to provide an equivalent service as an alternative.

I believe the problem is that people are put off these alternative tubes because they think supply could ultimately cause a headache.

My view is that there are far more stocks of these tubes than we realise, because there are so many held in small quantities in private collections. Also, it is only necessary to have a couple of spares, and a piece of tube equipment is future proof.

I have this idea that there should be a site where we could register our collections, creating a virtual warehouse, so that designs using more esoteric tubes could be built and promoted.

Other examples are 7C5, ECC40, EF40, 5B/254M and so on. Would be great to low the dust of these excellent audio performers.

[eddie_ce]

I have this idea that there should be a site where we could register our collections, creating a virtual warehouse, so that designs using more esoteric tubes could be built and promoted.

I have been thinking exactly the same thing. I have quite a selection of NOS valves, most of which I will never use. It would help us all immensely, to be able to exchange valves, however human nature being what it is, I fear there would be some potential for misuse of the service and unwanted "profiteering".

Mods. - Perhaps, if enough interest, this should be a separate thread?

[Radio Wrangler]

Do we want to encourage more construction of valve equipment? Such construction seems to be very strongly dominated by audio equipment, and that would run down stocks leaving radio and TV equipment without spares. We've seen the audio demand vacuum-up all the power triodes and many NOS power valves and rectifiers.

This is a principally restoration forum, so the repair of existing period equipment ought to take priority over building new equipment.

Where supplies have been exhausted, then a repairer of period equipment will need to investigate substitutes, but I'm uncomfortable about steering the new-build audio demand onto valves they've missed.

I'm reminded about folk medicine and the poaching of tigers and rhinos.

David

[Rileyman]

Excellently put , David .

Laurie .

[GrimJosef]

EF86s are, of course, in current production.

While it might be true that there are 'plenty' of old-stock valves out there, actually finding some when you want them can still be difficult. That said, Langrex are showing 585 6BR7s in stock.

Cheers,

GJ

[Radio Wrangler]

585, but that number will only move downwards, and 585 is all we've got to cover us for eternity. EF86 on the other hand are being made and remain with unlimited availability.

It seems to be only audio valves which are still in production. Everything else was just frozen some time ago. It seems senseless to use up a limited resource as an alternative to something fully available.

We have a number of 'consumables' to contend with. Radio, TV and professional Valves, some transistors, cartridges, styli, tape heads. They set the limit on how long we can keep period equipment in action.

3D printing will really have arrived when it can make any of those items!

[Richardgr]

The recent shock to the supply of valves from Russia highlights that the predominant use is of a very small number of different types: EL84, EL34, KT88, 12*u7, GZ34, and a few others; driven by the guitar brigade.

We've seen the audio demand vacuum-up all the power triodes and many NOS power valves and rectifiers.

I suppose you are referring to tubes like GZ37 and PX4. I confess I bought an old radio for the RCA Arcturus 2A3, but it tests 1% and the radio would be worth less than a replacement, even if there were any radio stations left to listen to.

I understand your point, but I think there is middle ground.

I have somehow accumulated 5000 tubes, and have around 2000 different types. Anyone care for a PL5727? I have cornered the world market for ECH81 ... This time next year Rodders!

The tubes will not last forever. Eventualy they will all succumb to gas and be useless.

I'd love to see more PCB type circuits where the PCB has a hole for the socket so different pin configurations can be used for tubes in the same role, encouraging fans of NOS tubes to try alternatives.

It is not just so I can make millions from my ECH81 hoard, but so I can do as much as possible to ensure the tubes I have are used or find good homes, and not dumped when they are useless or just consuming too much storage.

[Richardgr]

585, but that number will only move downwards, and 585 is all we've got to cover us for eternity.

I have 11 [of 6BR7], and I am sure that many thousands of collectors like myself have similar amounts.

I bought 300 CV4024 as part of my pension plan, and it turned out to be an OK investment on paper. But try to shift more than 2 CV4024 a month! It is not easy. The market really is very small for anything that is not currently being used commercially, and even CV4024's only appeal to tube rollers.

[joebog1]

As I have proven in the past, I have a large stock of NOS valves, I generally give them away, especially to the folk here. There are the snakes of course, that get them off me, then they appear on those auction sites with astronomical amounts on them. So I have been on this forum long enough to know the regulars and the genuine requests for something that cant be obtained at "home ".
Its just a suggestion, but maybe we should all part with some of our "junk ", and help those needing a hand. The amount of "junk " I have is much too large to fit in the box with me
so I donate it.

Joe

[Richardgr]

Exactly Joe! Plus there is that horrible feeling that with an untimely demise the treasures could be indistinguishable from 'junk' in the eyes of a non-enthusiast, resulting in multiple untimely demises!

[Valvepower]

Hi,

Just my two penn'orth and I’m defiantly not wanting to upset anyone as it's just my opinion

Thinking, this also stands for standard ‘domestic’ audio amplifiers as well.

I’m not happy with discouraging the [young] guitar amp builder, which there are quite a few, from using original valves in ‘say’ that ‘special’ Fender or Marshall clone and discouraging them from using original old 6V6, 6L6, KT66 and EL34’s etc., …if they have deep enough pockets to buy them

I know some amp builders use EF91’s and EF184’s – so the more advanced will try substitutes, however if you hanker after a classic tone and your ‘tweaking’ expertise is lacking then you’ll head down the traditional valve route.

I’m thinking there is young ‘thermionic’ blood in the guitar amplifier builders, and we should welcome them in and encourage them, and not hinder them as they will keep the thermionic technology alive (valves permitting) when we have all gone.

They appreciate old valves as much as we do, and because of the ‘sound’ of these original valves, they want to use the original valves where possible as the type of output valve is important to the sound they want, especially if they want to sound like their hero’s like Eric Clapton, Eddie Van Halen, Mark Knopfler, Jeff Beck, Robin Trower, Hendrix and Brian May and many, many more.

One of the lasting images of the Jubilee was Brian May using a wall of AC30’s which have 4x EL84’s

Quite a few of these guys are also restoring classic gear for gigging use, and will use new production valves here, but for that ‘special’ build they want the real deal ‘old’ valves.

I'm currently working through my stuff slowly building [clone] amplifiers so some of the parts sitting in the workshop will survive into the future and get used in an amplifier, which is more likely to be used than just sitting on a shelf awaiting the indignity of the indistinguishable 'junk' demise.

Sorry if I’ve upset anyone and I apologize again If I have.

Terry.