What are these tubes

perhaps a picture of the tube could help people in assisting you.

The Tung-Sol 6SL7GT is probably just that, and, if it is still a good tube, it's probably a really nice one. The two Raytheon's are probably 6SN7 GT's since that is what the tube complement information calls for. The power tubes should be four KT 88's. If you wanted to replace these tubes, you should be looking for one 6SL7 and two 6sn7gt's. I don't know if your unit is self biasing or not. It probably isn't. If the power tubes need replacing, it should probably be done by a qualified technician. Do not remove the power tubes without noting which socket each tube should return to. The other tubes (6sl7,and 6sn7's) can be removed and replaced at will, with the 6sl7 going in the 6sl7 position and the two 6sn7's in their respective positions. Happy listening.

if you search on "6SL7GT" on Tubes Asylum you'll get a lot of info on that one.

Mcfarland, the integrated amp had 6550's in it when I bought it, but I replaced them with KT 88's last year and they're still in good shape.

The unit is not self biasing, and the manual is POOR at best. I don't know how to bias the Raytheon or the Tung-Sol tubes, and the manual doesn't have any information about them. Based on the condition of the power tubes when I got them, I wasthinking it would not be a bad idea to replace the pre-amp tubes.

I don't have any way to take pictures or post them. Sorry.

I don't really do anything on Audio Asylum - I haven't found it to be very user friendly. I'm not really very good at this computer business.

The numbers you are referring to are mfg. codes. I'm guessing but it might be factory code (230) and date codes (5-52) may mean the tube was mfg'ed either on the 5th day or in the 5th month of 1952.

The Tung Sol 6sl7 and the two Raytheon 6SN7GT's do not require biasing. Therefore, test and replace at will! I say test because the Tung Sol 6SL7 is likely a VERY nice tube indeed. A good source of 6SN7GT, can be found at Andy Bowman of Vintage Tube Services, but Russian, and Chinese varities are plentiful and not bad at all. Try the Electro Harmonix versions, cheap and servicable. Ralph Karsten at Atma-Sphere.com can hook you up with Chinese versions, if you really can't find them anywhere else on the net (Tubeworld, Tube DepotVacuum Tubes, Inc., etc., etc.,). Just Google 6sn7gt and see what comes up. I hope that you had the KT 88's biased when you put them in. If not, get thee to a qualified technician (should not be too hard to find in the Yellow Pages of your area) Electronics professors at local technical colleges may also be able to help you. If you really can't find a good pair of 6SN7gt's, I can sell you a pair or two of mine.

Viridian should I wait till they cool off first : )?

Mcfarland, are the two Raytheon tubes really 6SN7GT's? There is no paint on them at all, so I have no way of determining their lineage.

I did bias the KT 88's when I installed them. I had to since one of the 6550's was pracitically blinding me,it was running so hot.

Do the numbers I gave for the Raytheon tubes indicate their age? The bases of the Tung-Sol and the Raytheon are a dark orange color, if that means anything.

There is a guy here in town that can check the tubes. He has a repair shop that is most definately not geared toward HiFi. For that reason I would be disinclined to buy tubes from him. He is looking toward functionality rather than ultimate quality. Of course you could say that about me considering the integrated amp I am using.