Using digital preamp to tube power amp questions


A while ago I was looking into trying tube amplification in my system and received a lot of good advice here. However, at the time I was using Martin Logan electrostatics and just couldn't get comfortable with issues related mostly to the inordinately high current requirements of these speakers. Recently, though, I bought a pair of Serie Reference 3A monitors which I seriously like and decided to pursue the idea again.

The reason for this post is to seek advice regarding the use of a digital preamp (Peachtree Nova) with a tube based amplifier because of the latitude I have with its large number of digital and analog source inputs. If the benefits of using tubes come primarily from the use of the preamp, I'll not pursue this issue. However, if those of you having experience with a similar setup have had good success I'd appreciate hearing from you. My current setup is this: Shanling CD-S100 CD player - Peachtree Nova as preamp - Behringer UltraCurve DEQ 2496 equalizer- Peachtree 220 amp - Martin Logan Ethos or the Reference 3 A's, depending on which speakers I decide to keep.
128x128broadstone
Tubes can definitely help with that...

Since you are not changing the speakers, my recommendation is to stay away from SETs, since they simply don't make enough power. You will want 30-50 usable watts; in an SET that means about 150 watts total! Not going to happen (unless you are in a small room, in which case a 20 or 30-watt SET might do).

We make amps that would work with that, and there are many others out there that will do nicely too.
Mechans, the Cary amp that I want to try hasn't yet become available so I haven't had a chance to try it. The request for advice, though, wasn't meant to solicit "what if" hypotheses; I seriously wanted to know if I might expect to hear a tube influenced improvement based on introduction of only this power amp. I've had almost no experience with tube based components except for when, going back to the late 50's, monaural and tube amps were the only choice. Also, over 30 years ago I discovered electrostatic speakers and have stayed with them ever since and, based on their inordinate current demands and advice I was given, I decided it best to stay solid state.

Now that I have these really nice monitors I thought it was time to see what I may have been missing all these years. Also, with age, my hearing is changing to the extent that I'm finding more and more music passages that I used to seriously enjoy have started sounding somewhat harsh to the point of discomfort. Now I don't expect tubes to be the panacea for these listening woes but if some of the edges can be rounded a bit and if tubes can contribute to this, the improvement would be welcomed.
So did you try it? Or are you just asking hypothetical questions regarding the possibility of such a set up? I strongly recommend you try it. I think you'll be pleasantly surprised. Theoretical audio is never a great substitute for the actual audio, except to rule out dangerous set ups.
What are your current concerns?
I would not use my rarest or irreplaceable tubes. Watch for specific danger messages from the manufacturer and don't doubt their sincerity. Do not attempt while inebriated, or otherwise not in full charge of your faculties! Relax!
Al, I have a call in to Mr Goka of Divergent Technologies to get what I can from him re this subject of sensitivity as well as his recommendations for upgrades or cap replacement for these 2 decade old speakers. I'm actually afraid to mess with them too much, though, they sound so good the way they are.
BTW, most of what I listen to has a fairly limited dynamic range and I listen to symphonic music only occasionally so, hopefully, that won't be a significant issue.
Thanks for pointing out the model number; I just knew that it was 2 monoblocks sharing the same chassis and thought they were the SE, not the B's. In reading the online 300SSE manual myself the rating published there is, indeed, 20 WPC. Considering the owner's opinion re the power rating, I'm beginning to wonder what the model really is. He did say it was a custom chassis and I haven't yet seen it.
Jim (Broadstone), according to the manual the 300SE is rated at about 10 watts, which actually is a bit more than is typical of many amps which utilize a single 300B output tube per channel. Cary also produced a 300SSE stereo amp, BTW, which used two 300B's in parallel per channel, rated at 20 watts.

Also, if the sensitivity of your 3A speakers is anything like that of the currently produced Reference 3A MM De Capo BE, a note of caution: Based on these measurements the 92 db sensitivity rating of that speaker is arguably optimistic by as much as 6 db (which is a factor of 4 in power terms).

Finally, keep in mind that the most important factor affecting how much power may be required will often and perhaps usually be the dynamic range of the music that is listened to (i.e., the DIFFERENCE in volume between the loudest notes and the softest notes, with well recorded minimally compressed classical symphonic music often being the most challenging genre in that regard).

Best regards,
-- Al
Atmasphere, much of your advice given to me in the past on this subject was during a time when I was committed to my ML's but now that I have started using these Serie Reference 3A's and I'm pretty sure I'm staying with them. These have an efficiency rating of 92 or 95 depending on which article I've read and the amp in question here has a power rating of 30-40 WPC. Is that something I can live with using a SE amp?
If you want to use a Single Ended Triode amplifier, you will need a speaker with a lot more efficiency! For best results, whatever the power rating of the SET is, it should not be driven past about 20-15% of that value. For best results.
Czarivey, input sensitivity for the 300SE is 0.75V for full output. The best I can determine is that the pre out voltage of the Nova is much higher than that so it seems that it should work.
ZD, I really don't know enough to make an informed decision about PP vs SE for my purposes. It would make sense, I suppose, to choose the more powerful amp if I were to choose to continue using the Ethos' as long as the current capability was adequate. On the other hand, if my understanding of their personalities is correct, SE would likely better suit my tastes. Also, price has to be a consideration in my consideration.

It looks like I've got some more studying to do.
If you are open to getting a PP 300b amp, look at a VAC 30/30 or 70/70. They're much more powerful amps. My 30/30 had no problem driving my SL-3's
Cary 300 SE may require high input voltage. Check the specs for input sensitivity. IF that's the case, You should check the output voltage of your PeachTree preamp.
I just got some info on the amp. If my understanding is correct, it essentially consists of a single chassis housing two Cary 300 SE monoblocks. I'm not at all familiar with tube specifics nor do I know the model number of the dual mono-block unit but from the little I've been able to read, it sounds like a pretty competent amp. Id appreciate any comments.
Thanks, that's good to hear. A friend has his eye on a used Cary SET for me (don't know the model yet) that it looks like I'll be able to audition in my home. I'll post the results. Also, I've pretty much decided that I'm keeping the 3a's in my system, anyway, whichever amp I decide to go with.
If you have tube poweramp and solid state preamp you will benefit from tubes. If you have visa versa you will benefit from solid state amp.
You will be very happy I bet with the tube output power. The precision of the digital pre will work great with the ability of tube power amps to create a holographic 3D sound stage. I don't think the electrostats will be good, go with the 3As and see if it makes you happy. I think it would. The Tube power amp is what really gives a system the benefits of tubes in my view.
Let us know if you liked it? There is always a chance that the system as put together just isn't synergistic of course , but I bet it will be really special.