Tubes for a Conrad Johnson 17LS?

There's a section of FAQ (Frequently Asked Quesions) devoted to tubes over at Audio Asylum with a LOT of information about 6922s and equivalents. I just bought a quartet of Amperex 6DJ8 tubes (6922 equivalents) and they are much better than the stock Electro Harmonix 6922s that came with my used 17LS2.

You can also play with pairs of tubes, recognizing that tubes 1&2, looking at the four tubes from the front, serve the left channel and tubes 3&4 serve the right channel. I've used Siemens 7308s (another equivalent) in positions 1&3 and Mullard E88CCs (yet another) in positions 2&4 with great success. Still trying to decide whether these sound better than the Amerex 6DJ8s.

Have fun tube-rolling. There are PLENTY of options. Dave

I am using Electro Harmonix gold pin 6922's in my 16lsII and like them very much. I have used Philips, Sovtek and Teslas in the past and find myself migrating back to the EH gold pins.

Chuck

Dopogue,

Should there be any concern with mixing 7308s with E88CCs (which I believe are 6922s) because of different electrical characteristics? The fact that you're doing this without any issues would obviously seem to indicate that there isn't any problem but thought I'd ask. I had read in a few other places that it wouldn't be a good idea to mix types (6DJ8s with 6922s, 6DJ8s with 7308s or 6922s with 7308s) because they are each somewhat different. Although mixing brands (Siemens, Amperex, etc.) of the same type would be okay and could lead to synergistic results.

Thanks,
Joe

Get to know the preamp in your system with the stock tubes then venture into NOS. Can get a bit pricey, but its hard to go back to the stock Sovteks.

Amperex 6DJ8s offer a touch of the romantic, with superb mids and airy highs - these were the ones I kept coming back to in my Premier 16. 6DJ8 Telefunkens are also wonderful but getting harder to come by. 7308s are a tad more neutral, not quite as seductive, with slightly firmer bass and clear highs. I could never use more than one Siemens 7308 per channel without bordering on the strident, but 7308 Valvos (Amperex Heerlen made) work great.

And Joe's right - unwise to cross mix types (not to be putting a 6922 in the same channel as a 6DJ8 or 7308). Brand mixing is where you'll find the 'blend your own' fun. Try for '60s thru mid-70's vintage. The nice thing about the 17 is you only need 4 and can begin to experiment with just 2. Check out the 'Joe's Tube Lore' FAQ on the Asylum to get one guys opine on many varieties out there.

Regarding the use of different tube types (2 of each), you're on your own here. I was told by someone I trust and respect in this area that there is no problem in doing so, and I've tried various combinations with no ill effects. I guess I'd like to see a definition of "unwise," Jtimothya -- what is the real downside?

I agree that you should get the measure of the stock tubes first, and they're really not bad. But I don't plan to go back to them anytime soon! Dave