A friend recently replaced his 17LS stock tubes with Philips Miniwatt 6922 SQ and he's quite pleased with the added extension they provide.
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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
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.
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
Hi Dave - The different types have different electrical characteristics - which is why they are different types. (For example a 6922 draws less heater voltage than a 6DJ8.) The circuit design of the 17LS creates a single 'composite' triode from the combination of the four triode sections in each channel. My suspicion is that the preamp performs better when that composite is created from tubes with similar versus different electrical properties. Other types of preamps may act differently - so the context here is the Premier 17/16/ART lineup which share a common topology. (The ACT2 is in the same family but its tube rolling opportunities are much more limited.) I do know that CJ told me they do not recommend mixing types in the same channel for those preamps.
If you've had no ill effects using different types in the same channel then that's great as you've got a broader range of combinations open to you! (Imo thats where the fun is.) Is your experience with the 17LS?
I got a 17LS recently too. One important thing is that the stock Sovtek 6922 sucks big time. I borrowed my friend's 17LS2 stock tubes (Electro-Harmonix 6922) and they sounded so much better. Sovtek sounds too bright, harsh, and lifeless...
I eventually settled down with a quad of Amperex 6922 (White letter, USA) and I'm very pleased with them. Bass and treble performance are excellent and image is better than the EH.
My other components:
CDP: ARC CD1
Speakers: VA Beethoven + Sequerra T1 Tweeters
I would definetly recommend switching the stock tubes.
As Tvad posted earlier he let me borrow a set of Philips
miniwats and the difference they made was amazing.
The Philips were much quieter and had better bass
extension. The midrange was more defined and detailed.
The original Sovtek tubes sounded muddy and congested by
comparison. I would never go back to the stock tubes
on my 17LS.
I really liked the Mullard CV2493 in my 17LS. But, I am only comparing it to the stock Sovtek 6922. In my area, availability of NOS tubes is somewhat limited. I found that the Mullard threw a much larger sound stage, particularly from front to back. I did not notice any difference side to side, but that may be room limitations. Also, compared to the Sovteks, the Mullard are a good bit airier.
Someone suggested this first - get really used to the sound of the Sovteks, to give yourself a reference point. Then, when you try different tubes, you can compare to the stock tubes.
I own a 17LS.
I need to replace the tubes. I don't have a lot of funds now for NOS tubes.
EH 6922 seems like a good choice for a stock tube with the CJ preamps.
I also have easy access to a local cryo-facility so may eventually try cryoing the EH 6922 to see what improvement is possible.
Question: There seem to be two types of EH 6922. Those with gold pins (a bit more expensive) and those with non-gold plated pins (not sure if these are steel or nickel-plated).
Are the gold-plated EH 6922 much better? If yes, what are recommended sources to get the gold-plated EH? I can get the regular EH 6922 locally (in Canada) from PartsConnexion or TheTubeStore.
Also for this application is it important to get matched/balanced tubes. Some vendors seem to offer this as a service, typically $5 upcharge. I called CJ and they sell matched/balanced EH 6922 tubes as well, $115 for a set of 4. Does anyone know if the CJ replacement tubes are gold-plated?
Thanks for your input.
I use the gold pined EH6922's in my premier 16 and I am very satisfied with them. I can not comment as to their sonic superiority over the non gold pined. You can buy the gold pined ($15.99) and non gold pined ($8.99) 6922's by a venfor on this site. His user name is 4380134d on audiogon; he currently has an active ad running. I have bought from him in the past and can recommend him.
I do not believe cj sells the gold pin version; you would have to ask them. I would not concern myself with matched pairs for signal tubes, such as the 6922's. Only power tubes and then only if you have limited ability to bias the power tubes.