Wanted 5687 valve

I have a mad assortment of 5687 in a box, many are RCA but I have quite a few other types.

Watford Valve had a few interesting NOS types last year at not crazy prices I seem to recall

Thanks Simon,
I will have a look.

http://www.aca.gr/index/hiend/hiendArticles?row=2609

Thanks Dave,
Interesting article.
funnily enough I have just orderd a 5687WB-SIEMENS which is a Tung Sol long black plate, looks like the ones in the article.
Got it from Watford valves thanks to the rec from Simon. Will be interesting to compare it to the Raytheon that Chris is kindly lending me.
I wish Watford valves would quote prices inc VAT. i know they donā€™t but it is still a nasty surprise at checkout

I have some of those Siemens and rather like them

It would appear I have:

4 x Siemens WB
1 x GE wa
5 x Raytheon WA
6 x Jan Philips WB
7 x Sylvania WA
11 x RCA
2 x National
6 x assorted without brands printed on them

Btw if you really want a change in presentation, try GE 7044 or Mullard E182CC
Both plug in alternatives which will change presentation far more than just switching between 5687. Be warned though they may remove some of that lovely 5687 fruity flavour

I recently loaned an E182CC out to a customer to try in a line pre and he said it was ā€˜unusably microphonicā€™. Of course this was just one example and could have been a bad 'un I suppose. But the long version of its datasheet does say

ā€¦ for use in computer circuits ā€¦

and

ā€¦ it is not intended to be used in circuits critical as to hum, microphony or noise ā€¦

VB

VB
Agreed, the datasheet does say that, but I know it has been used in audio for over 20 years, Border Patrol in particular used it as the driver in his 300B SE power amp for a long time, and I have come across it in line stage preamps and DACs, but you are correct it was not originally intended for this, and there is a risk of microphonics, but this is often the case with 5687 as well, and particularly with DHTs like 26, 801A etc but it doesnā€™t seem to stop people using them.

Possibly also user/system acceptance of microphony is likely to vary quite substantially :grinning:

I gave @PapaLazarou some E182CC a couple of years back, donā€™t think he uses them, though, I believe he preferred the standard 5687 types.

I only have boring GE ones. :frowning:

Yup. Microphony is a signal-to-noise problem of course. With perhaps 30-40V RMS signal driving a 300B no-oneā€™s going to notice 10mV of microphonic noise. But with a 300-400mV signal in a line-level pre they certainly will. My customerā€™s pre has a 5687 in as stock and it is true that thereā€™s some microphony in that. I think if it were mine I might have fitted a vibration-isolated socket to it.

VB

Isnā€™t the forward current sufficiently different in those two that it may affect performance in-circuit? Fairly sure Graeme or Guy put me right on that recentlyā€¦ If only I had braneā€¦ :brain::brain::brain::brain:

5 star?

Great band.:smile:

Whatever was in the phono!

Not any more. :heart_eyes:

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E182CC has a mu of 24 and a gm of 15mA/V.

5687 has a mu of 17 or so and a gm of 8.5mA/V (although that depends quite a lot on the operating point).

So they arenā€™t the same valve. But for tube-rollers the choice is extremely limited given these valvesā€™ uncommon pin-out.

VB

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Canā€™t help wondering if thereā€™s a Russian near/equivalent out there? The usual sources donā€™t list one, but since they made versions of most things, youā€™d think there would beā€¦

Then again slavic pragmatism means if they did, it would have a common pin-out with all similar tubesā€¦

I think the question about a Russian 5687 replacement has been asked several times and the answer always comes back that there really isnā€™t one. They do make a very nice high-perveance (what a nice word) double triode in the 6H30Pi of course (mu of 15, gm of 18mA/V). But it has the very much more common a-g-k-h-h-aā€™-gā€™-kā€™-s pin-out.

VB

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Word Of The Day!

6H6n has a mu of 20 and transconductance of 11mA/V but again pin out is as per 6H30 so not much help unless a bit of pin re-configuring is done.