Power Amp To Go With Cary SLP98P Preamp

John Atkinson’s measurements of your preamp indicate that while it has a fairly low output impedance at mid and high frequencies its output impedance rises to a very high 6800 ohms at 20 Hz. That would not be a good match for the 22K input impedance of the 200.2 ES amplifier.

And in fact it wouldn’t surprise me if the thick and sluggish sound Avanti1960 described as resulting from a pairing of the SLP-98P with a Parasound A21 (33K unbalanced input impedance) was contributed to by the interaction of those impedances, and/or by other effects on the output stage of the preamp resulting from loading it too heavily. IMO you should look for a power amp having an input impedance of no less than 47K. (Your present amp and the other Cary amp you referred to have input impedances of 100K).

Also, JA’s statement in the preamp review that the rise to 6.8K "will prematurely and audibly roll off the bass with power amplifiers having an input impedance of much less than 20k ohms" is much too lenient IMO. I say that in part because the result with load impedances that are significantly higher than 20K, as well as lower than 20K, will be undesirable phase shifts in the bass region, in addition to the small amount of frequency response rolloff he focuses on.

Good luck. Regards,
-- Al

Wow almarg! Thanks for the info. I had no idea. Heard lots of good things about this Preamp. Should I trade it in or look for a different power amp. Any suggestions?

I am surprised that the 2 power amps Cary referred to me will not work with my Preamp since they are both made by the same company and should work together. Confusing stuff. Maybe I should just get an integrated and be done with all this confusing matching.

Heard lots of good things about this Preamp. Should I trade it in or look for a different power amp. Any suggestions?

I have no experience with Cary or PrimaLuna products, but if I were to hazard a guess as to which of the two components is the weaker link **in your particular application** I would think the amp is the likeliest candidate. The reason I say that is that a number of PrimaLuna amps have unusually high output impedances, and if (as I suspect) your Dialogue Five is one of them that would make it a less than optimal match for the low (4 ohm nominal) impedance of your Ryan speakers (and perhaps for the Triangle speakers as well, although I couldn’t find much information about them).

For example, in JA’s measurements of the Dialogue Premium amplifier the following statement appears:

The output impedance varied widely, from an extraordinarily high 15 ohms with EL34s and 14 ohms with KT120s from the 16 ohm tap, both tubes in Ultralinear mode, to 2.4 ohms with EL34s and 2.15 ohms with KT120s, both tubes in Triode mode, from the 4 ohm tap. The output impedance from the 8 ohm tap was lowest with both tubes in Triode mode, at 4.6 ohms (EL34s) and 3.9 ohms (KT120s). Changing to Ultralinear mode raised these impedances to 7.9 and 7.4 ohms, respectively.

With these high output impedances, the DiaLogue Premium’s frequency response will be altered to a significant extent by the Ohm’s law interaction between these impedances and the manner in which the loudspeaker’s impedance changes with frequency. The gray trace in fig.1, for example, shows the amplifier’s response with Ultralinear KT120s driving our standard simulated loudspeaker. The variations are a very audible +4.5/–4dB. Even with the lowest output impedance, with KT120s in Triode mode driving the load from the 4 ohm tap, the variations are still ±1.2dB (fig.2), which will be audible.

Also, if you do choose to replace the amp I believe you would be very happy with the XA30.8 that was recommended by Three_Easy_Payments. I say that as a very happy owner of the somewhat less powerful and less expensive Pass XA25. Both amps, btw, are **far** more powerful than their published power ratings suggest. (Avoid the XA30.5, btw, as its input impedance is too low to be a good match for your preamp).

Good luck. Regards,
-- Al

P.S: I’ll add to what I said in my previous post that an amp having particularly high output impedance also, by definition, has a particularly low damping factor. That may also result in your amp being a less than optimal match for one or more of your speakers.

Regards,
-- Al