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Post subject: Unknown tubes
Posted: Mon Dec 26, 2011 3:46 pm
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Hi, can someone help me identify these tubes. I think they are 5881's but I'm not sure. I am building a 5E3 type amp with a solid state rectifier, fixed bias, and Blackface Deluxe transformers. I don't want to use 6V6's as the plate voltages would be too high with the SS rectifier.

Here is a link to Photobucket with some pics: http://s169.photobucket.com/albums/u217 ... n%20tubes/

Thanks for the help.

Bigampdaddy


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Post subject: Re: Unknown tubes
Posted: Mon Dec 26, 2011 9:27 pm
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These are NOT 5881 (6L6WGB), like the mil spec TungSol of the 1950's. Most ppl I know set them up based on old 6L6GB standards (see link). Plate voltage is very criticial. Don't go too much over 325-350 volts. And 17-19 watts of dissipation per tube, max.


http://www.mif.pg.gda.pl/homepages/fran ... /6L6GB.pdf


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Post subject: Re: Unknown tubes
Posted: Mon Dec 26, 2011 11:23 pm
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bigampdaddy wrote:
Hi, can someone help me identify these tubes. I think they are 5881's but I'm not sure. I am building a 5E3 type amp with a solid state rectifier, fixed bias, and Blackface Deluxe transformers. I don't want to use 6V6's as the plate voltages would be too high with the SS rectifier.

Here is a link to Photobucket with some pics: http://s169.photobucket.com/albums/u217 ... n%20tubes/

Thanks for the help.

Bigampdaddy


Use JJ 6V6S tubes. They are rated for 450 VDC plate voltage.

http://www.jj-electronic.com/pdf/6V6.pdf

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Post subject: Re: Unknown tubes
Posted: Tue Dec 27, 2011 2:03 am
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If outright righteous tone is what you are after. And your amp runs 325-350 VDC on the plates (like some old Gibsons, Riks, and woodie Fenders)...

These are the tubes you want. I bought a bunch for like $5 each in the 1990's, when everyone was after RCA 6L6GC and Svetlana SV-6L6GC's. The 6L6G, GA, and GA-Y (I kid you not... GA-Y) are to die for. Very close in tone and OD to the 1940's VT 107A and B's (mil spec 6V6G/GT) and 1950's 6V6GTY's.

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Sexier tone than.... almost

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Post subject: Re: Unknown tubes
Posted: Tue Dec 27, 2011 6:50 am
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I like those tubes! they look full and robust!


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Post subject: Re: Unknown tubes
Posted: Tue Dec 27, 2011 7:46 am
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Nice er, uh, tubes. :lol:

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Post subject: Re: Unknown tubes
Posted: Tue Dec 27, 2011 7:51 am
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I believe that the 6N3C in the OP's link (although it isn't actually an "N") is made in the Russian Reflektor factory and is basically a 6L6GT, similar to a 5881. So the 6N3C can be used in just about any spot that a 5881 or 6L6 are used, even though the 6N3C is a lower rated tube (18 watts, 350 Plate volts?). This tube is known to be very rugged and is hard to kill even when rated Plate voltage and wattage are greatly exceeded.

The JJ6V6, and GT 6V6 S are rated 500 Plate volts, 14 Plate watts.

The 5881, 6L6GB, 6L6WGB are rated 400 Plate volts, 23 Plate watts.

The EH 6V6 is rated at 450 Plate volts, 14 Plate watts, but only 350 volts on the screen.

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Post subject: Re: Unknown tubes
Posted: Tue Dec 27, 2011 9:03 am
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Shimmy, from the experience I've had with hi-fi amps and this Reflektor tube... first the tone isn't so good. You know it's a 6N3C, due to the regular big base. The better 6N3C-E has a coin type base with the OTK mil spec stamping.

Second... you cannot run the plates over 375 VDC. These tubes are noted for shorting out. They are based on the older RCA 6L6GB data. Follow those parameters & you'll be ok. Except for the tone. NOS 5881's can take 450-500 VDC on the plates regardless of what TS data sheets say. TungSol and Raytheon ALWAYS under-rated their tubes (maybe as a military secret?? ) :lol:

And as for tone... I really don't think either ever made a bad tube.


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Post subject: Re: Unknown tubes
Posted: Tue Dec 27, 2011 10:51 am
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BMW2002Ti wrote:
..under-rated their tubes (maybe as a military secret?? )..


Yep, and the same applies to the 6N3C, they are a mil-spec tube, and these tubes are routinely used with 500 Plate volts and more, no problem. They are used a lot in Russian amps, and the feedback that I've seen is very positive, very few problems when extremely overloaded. The Russian tubes are well known as some of the most rugged on the planet, and can routinely handle abuse better than most any other tube. The same "rumor" if you will, for the 6N3C is that they are very under rated due to some secrecy. I am sure that many, many tubes are under rated for one reason or another. I believe that the first 6N3C tubes were made on equipment provided to Russia from RCA, and were likely a very close copy of an RCA 6L6 xx. :idea:

Yes, I bet that a hi-fi wouldn't be nearly as good an application, for the reproduction of tone, very unlike a guitar amp which actually produces its own tone.

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Post subject: Re: Unknown tubes
Posted: Sun Jan 01, 2012 10:33 pm
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Wow!!! :D Thank you for all the great replies. I do so love a big pair of vacuum tit.....uh, I mean tubes. :lol: I just noticed that the email address in my profile was an old one that I hardly ever use. I have updated that so I will get your replies. I think I will wait and get a pair of the JJ 6V6's. Here is the link to the amp I was going to use them in. http://s169.photobucket.com/albums/u217 ... /My%205E3/ It started a your basic 5E3 circuit.

I made just a "few" modifications. I used Classic Tone Blackface Deluxe transformers, a fixed bias circuit also from the BF Deluxe, artificial CT on the filaments, elevated the filaments, solid state rectifier using 1200V/11A FRED's, raised the filtering to 30/30/16uf's, switchable bypass caps-.68 or 22 uf's-on the 2nd gain stage, and a nice mod to seperate the volumes which I got from Bob at Modern Valve Amps who in turn got it from Mission Amps, split cathode with .68 and 22 uf caps, and finally I used shielded wire for the input grid resistors and volume pots. I figured I should stop there. :D If anyone wants the directions for the volume pot mod just pm me.

Thanks again for all the posts.

Ivabiggun


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