Wanted to bring this topic up again as this unit has been in circulation over a year now. Anyone out there tried other than the stock tubes and found improvement?
I rolled a couple of NOS t7s, and liked the Telefunken ECC801S best. The other t7 were 6201 RCA blackplates, which were nice but not as detailed or extended as the Teles. I also tried a pair of u7s, RCA cleartops w/gray plates, and they were airy and sweet but didn't have the soundstage or presence of the more powerful t7s. The volume control with u7s was much more controllable though. The stock tubes that came with the 150 had no lables, but Paul tells me that they're "a Chinese Mullard double mylar knock-off T7's." I think we can all agree that the stock tubes are nice, but quality NOS tubes really take it up a few notches. The change is very noticeable, and my cds/mp3s have new life. In fact, I've stopped my hunt for a tube cdplayer - for now. Btw, my amp is Paul's TAD-60. I also rolled the pre tubes there and the difference is just as great as rolling the powertubes. I settled on a x7 Mullard short plate, but want to try a long plate and Bugleboy next. Also, I responded last night, but for some reason it didn't post, so my apologies if posts twice.
I rolled the stock tubes out of the 150 with a set of Tele 12ax7s and as one might expect they were a huge improvement over the stock at7s. The at7s seemed to put all the instruments in the middle. It was all depth with very little width. The Tele ax7s widened the sound stage considerably while keeping a nice center image. Right now I have a pair of Sylvania 5751s in there and they are excellent too (the teles went back in my Fisher 400). Sound stage is wide, excellent center image and wonderful detail. These also give you slightly more play with the volume knob. 11 o'clock is very loud though.
I also have the TAD-60 amp and have changed out the Sovtek 12ax7 to a NOS Mullard and the 12au7s to a pair of GE. A nice improvement again over the stock tubes. I run a quad of Valve Art KT88 and I like them much better than the stock EL34's. The bottom end is now to die for.
I've tried the following tubes;
Stock chinese 12AT7-dry and quite harsh
Brimar 13D5-not much better than stock
RCA 12AU7 cleartop- nice tube, good bass extension and great highs.
RCA 12AU7A- same as the cleartop.
Tunsgram ECC81-much more interesting. similar sound as RCA cleartops with more gain
Sylvania 12AT7WA green label-now were talking great tube.good bass extension,lush mids and crystal clear highs.
Sylvania JHS 12AT7WA-even better than the above tube. It was described to me as the Bing Crosby sound. It is that.
Last I tried a pair of GT12AX7M that I had originally had in my TAD-1000 amps. This was quite a shock as it was very near to the Sylvania JHS tubes, readily available, cheap, and more gain.
Yes I've been very busy this past year
Ecruz: The 5751s are much better than the stock tubes in every way. Comparing the 5751s to the Tele AX7s I would say that the bass is tighter and more defined with the 5751s. They both put out sweet mids and highs. I'd probably give the edge to the Teles in these departments though. Both tubes are excellent.
Onotu2: I used smooth plate Teles. I like the Teles better in my Fisher 400 than the 5751s. So I made the switch back. I am very satisfied with the 5751s in the TAD-150 though. You really never know how a tube will perform in a circuit until you try it.
Getting to the tubes in the TAD-150 is a bit of a chore...you need to unscrew the top screws as well as the four upper screws on either side of the unit. After you remove the cover, you need to unscrew the two screws that secure the reflective chrome "box" that sits behind the tubes, then slowly (and carefully) slide out the box.
Re. tubes, I had very good luck with a matched pair of cryo-treated Ei ECC83 (12AX7), which were also quite reasonably priced. I am currently using a pair of matched NOS Telefunken 12AT7 from Andy at Vintage Tube Services. The sound is amazing but they weren't cheap.
Interestingly, I tried one of the Groove Tube "Mullard reissue" 12AX7s in the 12AX7 slot of the TAD-60 and found it produced a bit of hum in my speakers that I don't get when with other tubes...maybe I got a lousy tube, people seem to like it.
Well, on Mike's review, I picked up 3 of the Groove Tube remakes. Put two in the TAD-150 and one in the TAD-60. Hard to compare as it is like watching a movie for the second time and seeing the parts that you missed the first time but, it appears that I am hearing more meat and bite on the same tracks as I listened to before the change. Sounbdstage remains huge maybe a bit larger but, hard to tell exactly. ext up will be to replace the two AU7s on the TAD-60...
I have two shoe boxes full of input tubes I have rolled into the 150. I got plum obsessed with it for a while. I have now had Telefunken 12au7s in there for over a year. To my ears I have found nothing that sounds better. I have tried Bugle Boys, Mullards, various RCA and sylvania x7s and u7s as well as the Groove Tubes x7 (the only non NOS I tried). I never understood Paul's defense of the stock tubes which I found very lackluster. I know you had a 60 amp. Strangely enough I did not like the Telefunkens in the amp as I had two pairs, one for the pre and one in the amp. I ended up with some RCA 12au7 long black plates there which to my ears sound better. But in the 150 nothing came close. Many tubes were rich but none rich and detailed like the Telefunkens. It was exactly the detail I was looking for without going all the way to brittle. How are you enjoying the Hibachi amps (no grill jokes from me)? How do they compare with your 60?
I really liked the GTs. But they were a little more "in your face" than the Telefunkens. But, the differences are not stark, just noticeable. IMHO the GTs have been a little better suited to rock but I listen to mostly Jazz and vocals. The Telefunkens to me sound clearer, crisper and more detailed focused. The Telefunkens seemed to refocus the sound stage. I could have lived with the GTs or the RCA 5751 black plates easily though, they would have been my second and third picks if I were forced to rank them. GT has a new tube (can't remember was it a 12au7 or 5751) but I thought it might be interesting to try (would a little less gain in the GT make a difference?).
Siemans, No. Sylvanias, yes (may have been double micas though). I would have to dig to make sure. The Sylvanias I thought were very good. Nice detail but a little less body than the Telefunkens to my ears. But, I could have lived with them. I guess the reason I liked the Telefunkens was becasue they seemed to strike a balance between detail and body. I have not tried Valvos either and would have been interested in them as well as the Siemens. Bugle Boys seemed pleasant, but ultimately too bright after extended listening. Gosh, I just finally had to stop somewhere with the rolling-my wife threatened the UPS guy as well as me! she became much to aware of a potential box that may have a pair of tubes...