Class D amp with Tube Preamp Combo?

Hi Guidocorona,

It was one of the earlier Class D amps, though I don't recall the model number. I bet it was still low on the learning curve and subsequent models have been improved.

I am hesitant to talk about "tube magic," because it means different things to different people, and because MOST tube gear I hear completely lack what I look for in tube gear (particularly, high-powered pentode amps driven by KT-88/6550s disappoint). In my setup, I did not fully get what I was looking for until I found a suitable tube linestage and a tube phonostage to match with my parallel single ended triode amp. The Levinson No. 32, which I still keep as a backup, did not quite deliver what my Emotive Audio Epifania delivers.

I am not saying that tubes are superior. In systems where more power is needed, I think that solid state is often much more desirable than high-powered tubes -- different horses for different course. I bet Class D would be the appropriate choice in some applications. The point is, one cannot make a generic choice, trial is the only reliable method. Also, I think one will usually not find success trying to compensate for strengths and weaknesses based on perceived individual qualities of particular components; the results are too haphazard for that.

There is a lot of practical sense in sticking with one brand for amplification or to go with an integrated -- usually, a good designer has worked out such compatibility issues.

Hi Larry, do you happen to remember if the JRDG device in question was a stereo or mono amp? and if mono pair. . . whaht physical size/weight?
G

Hi Guidocorona,

It was a massive, single chassis stereo amp. I think the model number was 302, but, I am not sure. The owner used it to power Kharma speakers, but sold it in favor of a Hovland amp after buying a pair of Sonus Faber Anniversarios. We got to play with it prior to it being shipped to a buyer in the far east.

Hi Larry, yes the device was very likely a 302. I have heard it a couple of times, driven by an aRC Ref 3 in both occasions. 302 was JRDG 1st gen switching amp with internal PFC. . . not bad for a first attempt, but I also observed some of the problems you found: only very moderate macro and micro dynamics, and a treble that was not too extended. These problems are solved completely by its successor--the current 312 model. Conversely, a clearly anomalous/strange sound in the treble region was probably caused by insufficient breakin or warm up. Switching amps seem to be total bears and may require well over 1000 hrs of playtime to break in. . . or at least the JRDG 312 and NuForce V9SE definitely do. The symptom seemed to me of a treble that sounds almost harmonically disjointed from the rest of the audible spectrum, and disconcertingly displeasing to boot. . . but the issue goes away completely with proper break in and warm up. . . it's just an unusual temporary artifact of these devices.

Guido and I tend to agree, but I must report that my Continuum 500 seemed fully burned-in by 200-hours. Jeff is constantly improving, so maybe his latest capacitors or something else changed the burn-in characteristic.

Others I trust report 500+ hours for 501s and 201s, so I don't think that Guido is "hearing things" that don't exist. Instead, I think that the landscape is changing very quickly and Rowland evidently hit on several ways to advance his pre and power amps very recently.

Dave