Help to make a choice: BAT; VAC; E.A.R.

I'm using a PHI 110 which offers deeper better defined bass but lacks a bit of the excitement of the PA amp.

Rhljazz, I'm running the same amp. Could you elaborate upon what you mean by "lacks a bit of the excitement of the PA amp"?

How are you running the Phi 110/110: zero feedback/feedback, triode/pentode, single ended/balanced?

At this point I would characterize the PHI 110 as being a more polished sound. It is certainly more spacious sounding and has tighter bass control. The result being that it doesn't have the fat round bass and quite the treble bite that embellishs the 1960's jazz that I favor. I am using the amps single ended inputs with the feedback engaged and ultralinear operation. The N802's may be a bit too difficult to drive with the feedback disengaged. Some material sounds very good this way but sometimes certain upper mid frequencies seem to jump out or it sounds congested in the bass. The preamp is a Renaissance and I use Audio Magic Illusion interconnects and Audio Magic Excaliber speaker cables in my latest setup. As I said, this is a work in progress.
I have changed the input tubes to NOS black base Sylvania which I preferred over the chrome domes. The PHI 110 did not like my Nordost Thor power contioner so I have gone back to my old Power Wedge for now. I still need to experiment more with power cords also.

Rhljazz, thanks for your comments. I find my Phi 110/110 does not lack whatsoever in treble "bite", so I find your post interesting. Crazy how this is all so system dependent.

I used to run my amp exactly as you do. Whenever I switched to zero feedback, I experienced distortion in the upper mids and highs. Then, my APL Denon 3910 was modified with new output transformers to better match the VAC's high gain in zero feedback mode, and the modification has made an astounding impact. Now, I run the amp with zero feedback and in triode. The difference is stunning...much more expansive sound, although it doesn't have the spooky darkness of running with feedback. It sounds more live, and I suspect this would lend itself perfectly to the 60s era jazz you prefer. The highs are sweeter, and the bass control is still superb. I find I don't miss the little extra punch ultriode provides, even while listening to Metallica.

As usual, your mileage will vary. I simply share my experience because like you, I ran with feedback and in ultriode mode for over a year, and the change to zero feedback and triode was excellent.

Raquel, have you heard the VAC Phi amps (I own one). I'm curious to know if you could provide any comparison betweeen the sound of the Phi series and Renaissance 70/70?

Maril555:

It would depend upon the size of your listening room and the type of music you listen to.

The 30/30 will certainly drive the VR4, but my guess is that a 70/70 would be better on any 89 db. speaker. If immediate cost is an issue, you could buy one 30/30 now, and buy a second one later and then have them converted to 30/70 monoblocks, which would be basically the same amp as the 70/70 (the 30/70 monos may have more power supply capacitance and thus better sound, but I am not certain -- you would have to ask Kevin Hayes of VAC). VAC used to charge $500 per amp for this service. The most knowledgeable salesman at Singer in New York runs 30/70's. They are among the handful of best sounding tube amps out there.

As for the above comment about 300-B's costing a lot more than pentodes, that is true, but they also last three to four times longer. The other thing to remember is that the Renaissance 300-B amps auto-bias the output tubes, which increases tube life because the tubes never suffer the stress that can occur when they fall out of bias. I believe the PHi series amps auto-bias the KT-88's used in those amps, but a KT-88 will have nowhere near the life of a 300-B. The PA 100/100, for example, is a lot of amp for the money and sounds damn good, but you have to bias the output tubes and there is no protection circuitry on the amp. A big advantage of the Ren. amps is the auto-bias, the protection circuitry and the fact that 300-B's last so long -- there are simply no tube amp hassles and they are as trouble-free as a preamp. I don't know that I would have the patience to run a tube amp that does not have these features (most do not).

Good point about the heat -- the Renaissance amps are run in Class A and produce a goodly amount of heat. They are not outrageous like a Class A transistor amp, but my 140/140's, for example, will contribute heat to a room, no question about it. Whether this is an issue depends upon the size of the room and the ability to cool the room if there is heat build up.

As for running these amps in anything other than zero feedback mode, I would concede that it is a system-by-system thing, but the beauty of the amp and the design of the circuit is the fact that it is triode and uses no feedback -- the feedback control is a concession to marketing. If feedback is necessary, then I'd say that the amp is wrong for the speakers (on the four speakers I have run with the 140/140's, the amps of course sounded like a normal amp when any feedback was dialed in-- i.e., significantly less good -- there is a reason that high-end two-channel amp designers tend to try hard to avoid using feedback in their circuits).

One other point about the VAC Renaissance amps: for the first seven or eight years they were in production, the logo badge on the transformer housing was this huge, gaudy gold colored thing. They replaced it with a small, ovalular brass logo (... that, to my tastes, is discreet and tasteful) on later production -- they charged me $10 per amp to substitute new, small badges.