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Old 11th September 2006, 05:04 PM   #1
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Default 4654/4699 pentodes

So it looks like I can gets my hands on some 4654 and 4699 tubes - I've checked the datasheets and they're both described as "output pentode". I've never heard of them before, are there any schematics floating around where they are used?

Looks like 8-10W should be possible with a triode connected push-pull 4654 or 4699 amp. The only problem (?) is the weird socket.

Here are the datasheets:
http://www.mif.pg.gda.pl/homepages/f...046/4/4654.pdf
http://www.mif.pg.gda.pl/homepages/f...046/4/4699.pdf

Any thoughts?
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Old 11th September 2006, 06:44 PM   #2
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There were a couple of dealers in Norway that had these (Demostenes and ?). I have a few of them. Haven't used them so I'm open to ideas, or offers even. Very nice valves. I'm told the side contact bases can get stuck with the valves - hasn't happened to me but I was warned.

I have some notes off the Web:

"4654 and 4699 have a Pa= 18W (much like a 6L6), and are just TERRIFIC tubes; they were also made in Holland by Miniwatt (Mullard by the time). Appart from the anodic dissipation, they are the closest thing to the best EL34 that might have been ever made – 4689 is a highly rated 4699. The construction is superb (the anode, the rods, the metal ring...) and rugged, and looks cool too! Be careful 'cause the printing will go off easily.
I have played some with an UL single ended amp using two stages, E80CC driving. This amp sounds incredible sweet and pure, but lacks power. Clip is 3,5W, it sounds best below 1W. I have tried EL34, 807, E130L and PE1/100 (6083), but none could beat the distortion performance of 4654."

Late production cylindrical EL5/375, 4688, 4689, 4699, the standard EL60, EL61 and the few metal base Philips EL34s of early production in my collection all seem to share the same plate and basic internal construction. The screen grid in my EL61s starts to glow if operated significantlyc above 300V, and the anode shows a dark glow above about 22W - not a good idea for valve life - see my early 4688 amp (4V heater version of the 4689) - run at 25 W Qa like the EL34 in the 5/20 made them fail in a few hundred hours - with complete loss of slope and reduced vacuum. Pity, they were very nice.... The EL61s now used in the box have lasted for more than 3000 h without significant degradation in slope and emission - recently I checked them out, and found - within the accuracy of my VCM163 - no change compared to first insertion - operating point was 18W/375V/275V/48mA per valve. Therefore I recommend to be conservative on the loading of early 'cylindrical plate' EL34 versions... your mileage may vary, but given the cost of these things those days I'd be rather very cautious. The 4689 is a high reliability version of the EL5/375, an ancestor of the EL60 which in turn is the predecessor of the EL34. A datasheet for the original version can be found here: http://frank.pocnet.net/sheets/030/4/4689.pdf The K version is a late model with octal rather than outside contact plug. The 4689 was used in Cinema amps, PA systems and PTT applications. It reached the market in the ST shape around 1936, and in the shape shown around 1947. It can be used like an EL34, IF you keep Qa below 18W, Ua below 400V and Ug2 below 300V - the datasheet is a bit conservative wrt voltages - but power ratings MUST be observed... Run a 4689 at EL34 operating points and voltages, and you will loose it fairly quickly. Regards, ---mb---

I looked in my lab log about the 4654 amp (now the numbers are right!).The test was with grid leaks of 570k and 100k on the output tube. Here is the harmonic spectra:
2nd 3rd 4th 5th 6th 7th 8th
100k -58,9 -55,3 -70 - -91,5 - -94,4 [dB rel fundamental]
570k -57,8 -55 -73,8 -89 -85 -94,4 -92

With 100k grid leak, 2nd harmonic is lower, 3rd is about equeal, 4th is higher, and all the higher harmonics are lower.This test was made at 1W @ 1kHz, the amp clips at 3,5W. This was with my amp, it might be different with other tubes and configurations. If anyone wants to do a test on this, measuring or listening, it would be very interesting to hear the results. Regards, Bjørn

All the 4654 samples I have needed quite a lot of trial and error before achieving a satisfactory performance. The final recipe features fixed grid bias, triode connection, and 375V/50mA operating point. Around 12dB of negative feedback helps keeping the bass tight and controlled without noticeable effects in the higher frequencies.
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Old 11th September 2006, 09:12 PM   #3
coresta is offline coresta  France
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Hi Eusebius .
Are your Transcos sockets steatite ones ? I 'm looking for a quad of them for my 4654s !
cheers
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Old 11th September 2006, 09:39 PM   #4
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My sockets are kind of black bakelite - is that steatite? I need them for the stack of EL50s I have, I'm afraid. You should be able to get some in Holland from dealers I should think, or ebay.de Andy
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Old 11th September 2006, 09:44 PM   #5
coresta is offline coresta  France
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No Andy , steatite is white porcelain as Amphenol octals . Cheers
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Old 12th September 2006, 05:12 AM   #6
jlsem is offline jlsem  United States
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Quote:
The only problem (?) is the weird socket.



http://electron-tubes.info/eindex.htm
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Old 12th September 2006, 03:41 PM   #7
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Thanks for the info, Eusebius and jlsem!

I'll have to wait and see how many tubes I can get before I start planning an amp, but the description of them definitely looks promising. And they're a great excuse for designing an amp from scratch.
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Old 12th September 2006, 05:14 PM   #8
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Well - make me an offer for the tubes I have if you want - I may even give you a better price. I'm not using them right now. Vennelig hilsen, Andy
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