Transitioning from SS to tube amplification

Hi Jim (Broadstone),

I think I may have mentioned in one of your past threads that if the sensitivity of your Reference 3A speakers is comparable to that of the Reference 3A MM de Capo BE, per the measurements for that speaker shown here the 91 dB figure may be optimistic by around 5 dB or so.

Nevertheless, for solo guitar recordings, and for a considerable majority of recordings in most genres, I would certainly be surprised if the 35 watt capability of your amp proved to be insufficient.

A point to keep in mind is that what is usually the most significant factor in determining how much power is required is not volume or perceived loudness per se, but the dynamic range of the music that is being listened to. Meaning the DIFFERENCE in volume between the loudest notes and the softest notes, with well recorded minimally compressed classical symphonic music generally being one of the most demanding genres in that respect.

Many and probably most "pop" recordings, for example, are compressed to dynamic ranges of less than 10 db, which means that less than 10 times as much power will be required to reproduce the loudest notes as will be required to reproduce the softest notes. While many classical symphonic recordings will have dynamic ranges in the vicinity of 30 db (requiring 1,000 times as much power to reproduce the loudest notes compared to the softest notes), or in a few cases even more than 50 db (requiring 100,000 times as much power to reproduce the loudest notes compared to the softest notes; and no, that is not a typo).

For example, I have more than a few well engineered classical symphonic recordings in my collection which when played at modest average volumes of 75 db or so at my listening position, with the softest notes being in the 50 to 60 db area, will reach brief dynamic peaks of 100 to 105 db at the listening position. So most of the time the amplifier is putting out tiny fractions of a watt when playing those recordings, but brief dynamic peaks will require a great many watts.

From a subjective standpoint, though, loudness tends to be perceived based on the average volume of the music, not on the basis of brief dynamic peaks that may last for only a fraction of a second. Bear that in mind when considering Grinnell's comments.

Finally, with respect the 10 o'clock and 9 o'clock level settings you mentioned, keep in mind that those settings don't necessarily imply very much with respect to power. The relation between volume control settings and volume levels relates more to the gains and sensitivities of the equipment than to the maximum power and maximum volume capabilities of the equipment.

Best regards,
-- Al

Jim (Broadstone), having no experience with PrimaLuna, Rogue, or Cary products, I can't add too much at this point. What I can say, though, is that among medium powered tube amplifiers I and a goodly number of other audiophiles do have a particular affinity for EL34-based designs (that being the output tube supplied with the PrimaLuna Prologue One, of course, although it can accept other types as well). And keep in mind, also, that an increase from the 35W capability of that amp to the 100W capability of the Cronus Magnum is an increase of just 4.6 db. Certainly a substantial difference, but by no means one that I would characterize as huge.

Best regards,
-- Al

Jim (Broadstone), 'twas I who referred earlier in this and other threads to these measurements of the currently produced Reference 3A MM de Capo BE, optimistically spec'd at 92 db and 8 ohms, and speculated that the sensitivity of your earlier Reference 3A model MIGHT be similar. That speculation seemingly having been confirmed by the dealer you spoke with.

The 86.7 db/2.83V/1m sensitivity for the MM de Capo BE that is reported in those measurements, btw, equates on a per watt basis to about 85.4 db/1W/1m in the mid-bass region (where lots of energy is typically required), given the speaker's impedance of about 6 ohms in that region.

That said, as you may have seen a few months ago in the long thread entitled "Building the Audio Note Kit 1 SET amp," member Rebbi achieved remarkably good results using that speaker with an 8 watt SET, albeit listening at modest volumes to mostly non-classical music. Eventually, though, he moved on to more efficient speakers. At least one other member whose inputs I consider to be especially credible, Brownsfan, also reported using those speakers with surprisingly good results using an 8 watt SET (the $6K Coincident Frankensteins), in his case mostly with classical music.

But personally I would not suggest going any lower than the 35W capability of the PL1, or perhaps the 30W capability of the Atmasphere S-30 (although I suspect that the M-60 would be a better match, in terms of impedance as well as in terms of power capability). Among the reasons I say that are the comments above by Tubegroover, Ralph/Atmasphere, and others, the somewhat large size of your room coupled with a greater than average listening distance, and my own philosophy that configuring a system in a manner that is marginal with respect to power should be avoided if at all possible.

Finally, one thing that might make the Atmasphere amps particularly worth considering, when and if your circumstances permit, is that based on all I have read about them I would expect they would provide extended and "fast" response in the treble region, with high frequency transients being reproduced in a "clean" and accurate manner, but without the overly bright sonic character that other wide bandwidth designs often seem have. All of which might result in their sonic character being a particularly suitable match for the hearing sensitivities you have described having.

Good luck. Best regards,
-- Al