This current combination is sounding pretty darn sweet in my setup at the moment. Current favourite! Holland (pope) 6SN7GT, Holland D getter EL84 and USAF 596

http://i128.photobucket.com/albums/p...psidkc5sos.jpg
http://i128.photobucket.com/albums/p...psekpjaijo.jpg
http://i128.photobucket.com/albums/p...psjc0fvivt.jpg
http://i128.photobucket.com/albums/p...psbgtplq1m.jpg

I'm going to look into this one. 48 steps and the resistor can be changed to suit your 'taste'.

Khozmo Stereo Shunt Stepped Attenuator, 48 step MKII

Whaddya know! I gave the EL84 with converters a shot and I am, mmm, converted! I'll stray back to my previous favorites: EL34 Xf2 with fat bottle GZ37 and see, but did once and came back to the EL84's.

I tried a few EL84 variants with the Holland (Amperex) D-getter also my favorite so far. I did get a pair of Amperex orange globe halo getter, but haven't listened to them yet. The D-getters seem to better vintage Telefunken and Mullard and new production Tung-Sol, I'm using vintage RCA 5U4G rectifier. I have a 596 and will have to give it a try with these.

The converters are YellowJackets. I consulted with the original designer (never could get a reply from the new owners) and was told the YJUni Pentode version was the most appropriate for the Inspire KT-150 design (yellowjacketstc.com/yellow_jacket/yjuni).

So, do you guys attribute the better sound to the EL84 tube by itself or to the special 6SN7 you're using? Also, is this small output tube able to provide enough juice to the system? Thanks for your appreciations.

For me, I think the difference is the EL84. I didn't change driver (I have the 6922 type drivers - using a 6N23P). I did change rectifier as the GZ37 may have run them too hot.

They power the system fine. I don't know the specs to know what output wattage I'm now getting, but I'm not noticing a difference in gain or difficulty at higher volumes compared to other tubes.

I second the use of a 5u4 type tube as the others just didn't sound smooth, mostly the top end sounded harsh. I have found the Holland made 6SN7GT to be the best all around driver tube no matter the power tubes. I have also found and surprisingly so that the output level with the EL84's is equal that of the KT88's and thats through 86db/watt Kef LS50s!

The EL84 is capable of 15-20 wattsi n push pull and 5 or so watts run single ended. I have a bunch of them, all 50's and 60's Aperex, etc. and will get adapters eventually.

Yellow Jackets? Where did you source them? There are different versions too.

From the web:

Yellow Jackets® converters are a type of specialized adapter which permit the use of EL84/6BQ5 power tubes in place of 6V6, 6L6, EL34, and 7591 type vacuum tubes.

Yellow Jackets® converters allow you to harness the musicality of EL84 vacuum tubes in amps that don't use them already - it's like getting a whole new amplifier! In place of a 6V6 a Yellow Jackets® converter will even out the tone and make it sound stronger. In larger amps that use two 6L6, 6550, 7027 or EL34 power tubes the Yellow Jackets® converter will drop the output power to about 15 to 20 watts, giving it more of a vintage VOX AC30 sound. In amps that take four power tubes the Yellow Jackets® converter will sweeten the tone and make it more dynamic. There is no rebiasing involved, which makes modifying your amp's tone very easy.

Yellow Jackets® converters give you simple Class-A operation from any amp. They not only rearrange the pin locations of the tubes, but also provide the necessary plate voltage drop and current limiting on the screens as well as blocking the amplifier's grid bias voltage while configuring the EL84 in a Class-A, self-adjusting cathode-bias circuit. In other words, there are no adjustments to make and no modifications necessary, you simply plug the Yellow Jackets® into the amp's output tube sockets, (in cathode-bias amplifiers) screw the ground wires under one of the output tube socket mounting screws, plug the provided EL84s into the Yellow Jackets® converters, turn on the amp and play.

All Yellow Jackets® have a two year warranty against manufactured defects.

Would these adapters preserve the Triode-strapped configuration in my Inspire KT-88 amp running EL84?

Looks like you found their site. I talked to the original designer who had since sold the line to a company in Canada. He took the info I gave him about the Inspire SEP amp and said that the YJUni Pentode version was the one to get.

5 watts makes sense. Lower end of the range for these amps. Seems to be plenty though.

I'm not sure of the terminology. Is the KT-88 design similar to the KT-150 design? Auto bias seemed to be one the biggest determining factors and I think all of Dennis' amps have been auto bias.