PREAMP technology shift? - Class A/ balanced/ dual-mono/ zero feedback vs. op-amp preamps

Hi @paulburnett, several years ago, I had the original Rowland Capri in my system for about 15 months -- a truly excellent preamplifier, which was a significant upgrade from the ARC Ref3 that I used before. The original capri was audibly superior to Ref3 on most all parameters: staging and imaging, authority and macro/micro dynamics, resolution and extension, harmonic complexity, as well as sweetness and control of treble intermodulation. The only marginal flaw I could detect is a certain shyness of fundamental frequencies in the deep bass... Although Capri had tremendous authority, deep bass notes were a little shy of fundamental harmonics. But at less than 1/3 the list price of Ref3, I could not complain... By contrast, Ref3 bass sounded somewhat muddled.

The original Capri was indeed based on the OPA1632, and like all Rowland preamplifiers, runs balanced in class A, with transformer coupled inputs and outputs implemented with Lundahl transformers. I call Capri a preamplifier in stead of a pure linestage, because you can add to it a phono card.... and in more recent times a DAC card instead of the phono.

The newer Capri S2 is outwardly almost identical, except for a new display and remote control... However, the circuit has been redesigned, and the OPA1632 has been replaced. I have heard Capri S2 at length at RMAF, and it is sonically significantly enhanced over the original.... The first thing I noticed is that the deep bass shortcoming is totally gone.... Deep bass is, well... Deep, without ever becoming bloated.... And overall Capri S2 is even more musical than the original.

You will find more information on Capri S2 at:

http://jeffrowlandgroup.com/kb/categories.php?categoryid=210

You can download the manual from my Dropbox at:

https://www.dropbox.com/s/89p3g48zgh6cava/JRDG%20CAPRI%20S2%20MANUAL%20REVA1.3.pdf?dl=0

Feel free to drop me a PM if you like any other info on Capri S2.

Regards, Guido

Woops, you are right Johnny, I should have given the context of my repeated comparisons.

I had both Rowland Capri and Ref 3 in my system using the following amplifiers:

Rowland M312: 40K Ohms inpput impedance.

Rowland M625: 10K Ohms

Rowland M725: 40K Ohms

Rowland M925: 40K Ohms.

I have never used Ref3 on lower impedance amps.

The source was the Esoteric X-01 Limited CD/SACD player in all cases.

My results were consistent for all linestage / amp combinations. I much prefered the original Rowland Capri over Ref3 in all cases.

Saluti, Guido

One more clarification.... Both Ref 3 and Capri were fully broken in.... REF 3 had a few thousand hours on it, and had fresh but broken in tubes for the SET Winged 6550 in the power supply and the 6H30s... Particularly important in the 6550... It takes this tube about 500 hours to reach full performance, and by 1000 total hours, it starts to sag.

Capri takes about 800 hours to reach maturity... Fresh out of the box, Capri is somewhat flat and blanched, and is easily outperformed by a well broken in Ref3.

After a quick initial comparison with Capri fresh out of the box, in which Ref3 was clearly superior, I did not apply Ref 3 again until completion of Capri break-in, so not to wear tubes down.

G.

My apologies Johnny, your automotive metaphores are quite impenetrable.

Per the following page:

http://www.aragonav.com/8008-bb-mondial

The Aragon 8008BB has a balanced input impedance of 44KOhms, which is commensurate with the 40KOhms of three of my amps. It does not appear to have the 100KOhms input impedance that you asserted.

Interestingly, the input/output impedance ratio of my 40KOhms amps vs Ref 3 -- as well as versus ARC LS28 -- is

40,000Ohms / 600Ohms = 66.66 (periodic),

which exceeds the minimum safe threshold of 20 by a factor greater than 3. This strongly suggests that my Rowland amps are comfortably compatible with REF3. Similarly, the corresponding ratio on the Aragon 8008BB is

44,000Ohms / 600Ohms = 73.33 (periodic),

which is not staggeringly different.

The hybrid ARC LS28 is doubtless a lovely linestage. I have heard it at RMAF, and liked it. From my admittedly non-tuboholic point of view, with its SS power supply, it has the advantage over the REF series of limiting retubing to every couple of thousand hours or more for the 6H30s, as there is no fast-burner 6550 in the power supply which in old REF3 required a replacement every 1K hours or so.

It is worth pointing out that at $7500 new, LS28 is almost twice as expensive as the Rowland Capri S2 at $3995. From sheer memory, and not having heard the two linestages in the same system, it was not apparent to me if LS28 yielded any audible advantage over Capri S2. On the other hand, a side by side comparison of a well broken in pair in the same system might shed some light about any relative audible advantages of one over the other. However, preferability is hardly an absolute: personal musical taste and sonic priorities of the end user play a major role in every evaluation.

Saluti, G.