Hi there,

First off....let me say your results will not only depend on your personal "taste" in music...and on your system...but also on the output tube your using. The best way to find out is to try...try...try. Lucky the 6sl7s are a bit cheaper than the 300B tubes or we'd all be broke.

My first 6sl7 swapping was with the WE300B tube. Some of the tubes I've tried...this is what I found(remember...your mileage most likely WILL vary based on system differences and personal taste)

Philips Jan 6sl7WGT - Here's a tube that's not often sought after. It has a nice laid back presentation to it. Seems to be clear and detailed with a decent soundstage. This tube seemed to just let the 300B tube be heard.

Nationa Union 6sl7 vt-229 - Alot of presence here. It seems to add more to the top end and just a bit to the upper bottom also. It has a bit more forward presentation with the WE300B. More dynamics and a wider soundstage. It did seem to "muddy" up the details a bit. All in all...after living with the tube for a while it was just to forward for me.

Sylvania 6sl7 vt-229 - Very similar to the NU tube. Added top...punchier bottom...wider...wider soundstage. But not as forward as the NU...still a bit forward...but just not as much. The Sylvania also seemed to "muddy" up the details a bit. All in all...not my tube of choice for now. Did I mention it has a very wide dynamic presntation though

RCA 5691(red base) - This tube...the first time I tried it was after the NU tube. It's definitly a different sound...much more laid back. A bit rolled off in the treble(compared) nice presentation but it just seemed to be not all that detailed and clear...just a bit. This is now compared to the Philips WGT.

Sylvania 6sl7GT(don't remember the year) (chrome domes) - I got rid of these I now wish I hadn't. they seemed to have nice detail...very clean. A laid back (easy) presentation. But they lacked a bit of dynamics and didn't have that huge soundstage. I'll try to get another pair.

These were all with the WE300B tube. I think that is important factor...change the output tube...try all the 6sl7s again. After all the tubes tried...I kept the Philips WGTs in. They seemed to have a presentation that I liked with nice detail...seemed to more so let the WE talk for the amp than the others.

TJ300B mesh (perf plates) - don't get me wrong...the WE are nice. I love the easy presentaion they have. But, the TJs seem to have a more extended top end. Notice I didn't say added top end(as before with the 6sl7s) more extended bottom end. More dynamic...cleaner, more detail. Still very musical. Nice tube! The soundstage is not as wide or deep as the WE tube. Also, the TJ is a bit more forward in it's presentation...not much...but a bit more.

Philips WGT - again...nice. Seems to let the TJ thru. Clean detailed...this is what I have in now.

NU vt-229 - again....dynamic...added top wide soundstage...very forward now...and a bit muddied.

Sylvania vt-229 - Dynamic, added top and bottom...wide...wide soundstage. bit muddied compared to the Philips WGT but not to bad. Again...presentaion is to forward.

Sylvania chrome domes - Now...I wish I had them back...I think this may be a good match. <

RCA(reds) - not to bad...nice presentaion...just a bit muddied on the details.

I really have to get me a pair of the old Sylvanias again! They were a bit light with the WE tube...but were very clean and detailed with a laid back presentation. Live and learn...still don't know why I got rid of them!


Once again...you mileage will vary...you have to find what suits you...and your system. When trying them...swap them back and forth if you want....then leave the tube in there for a week or two...to live with it for a while...


anyone have any other thoughts or experiences with various 6sl7 types? Love to hear'em!

Interesting - I'm going to have to try a few other 6SL7's after reading this. I use the JAN Phillips 6SL7WGT and WE300B tubes as well and pretty much heard what you did after replacing the Sovtek drivers - a little more detail, maybe a little deeper soundstage and most importantly for me - a smooth sound without sharp edges. This seems to be a nice combination with the sometimes forward nature of my Altecs and takes a bit of the bite out of the shiny silver beer coasters without giving up anything when listening to real music on vinyl.

Billf

I have a SRPP 6SL7 300B and I tried 2 types of RCAs that the main difference was in bottle height as far as looks go. The taller seemed to have more gain and extra hours did not tame its very forward mid and bright top. The short bottles were very much the same but the bright top settled down after around 15 hours. If I get ambitious I pop these in for movies as they are better at getting a bit more gain and forward mids are fine for movies.
Sylvania short bottle, brown base. Very nice all the way through a bit lower gain but quieter background making for better soundstage and lower noise floor than the RCAs. Very good and I recommend them, I have 2 pair.
RCA VT-229, enter the king. Everything opened up. Very low noise floor, better soundstaging especially in depth of as things feel more 3D. No weak points anywhere on the scale and were the very best thing I have heard so far. If you can get some of these do so.
300Bs= TJ Mesh

I do not have experience with the 6sl7 tube and limited experience with the 300b. So I'll limit my comments to the broader applications of the points made. My first explosure to valve amplification was with a Dynaco st-70 using EL34's. This changed how I related to musical replay and even music itself. Till that point, I preferred live music, and now there are times when I'm happier listening via playback. Least IMS.

As I became more experienced with various tube equipment and individual vacuum tube devices (especially vintage stock) I realized what effect tubes could have on the particular components and systems they were used. I also learned that, as in many aspects of audio, individuals often had differing opinons on any one valve or tube component. Agreeing on a favorite tube was like picking a favorite color.

Since aquiring my first SET amp in February I've used it in a variety of systems and find myself often reaccessing which tubes I actually like best. Change one thing and the previous "best" is no longer the best for that application. That's why it's a good idea to have a good selection of tubes on hand. Just recently, I've taken to changing tubes IMS based on the source material. I did this to see to what degree one tube could embellish a particular music type, as I have no desire to continously play "musical chairs" with my valves. I'd rather find one tube that benefits a broad selection of music. Though I do catch myself, now and then, changing tubes for the same reason people drive different cars - because I can. It's fun sometimes to swap tubes, as tube collecting is a hobby in itself but I don't want to become more focused on the devices than the music that lead us on this journey.

MikE

Found this great article on rolling 6SL7s by gonefishin in the archives. Worth reading again for anybody rolling 6SL7s