Is 260 ohms the pre-amp output impedance and 20K OHMS the minimum recommended amp input impedance maybe? Yes. |
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11-06-09: Newbee
In fact I'd take bets that it would be unlikely that he would hear any meaningful difference if the amp's input impedence was as low as 10K. If you heard the SP16 with two amps, one with a 10k ohm input impedance and the other with a 20k ohm impedance, I'd wager you'd hear a difference in the bass extension and clarity. If you didn't, then I'd be very surprised. |
Newbee, I stand by my statement that I'd wager you'd hear a difference in bass performance between a SP16/10k ohm amp combo and a SP16/20k Ohm amp combo.
Beyond that, no it'd be impossible to compare identical amps except for differing input impedances, as no such device exists to my knowledge.
No, I have not heard an SP16 connected to a 10k Ohm amp and a 20K ohm amp...or any amp for that matter. However, I would take your bet that I could hear a difference in bass response. |
Newbee, your viewpoint on the impedance matching issue that you illustrate in this thread is just flat out wrong.
The possibility that you may not be able to connect what you hear to an impedance matching issue does not mean the issue does not exist, or that is of little importance.
The difference between an amplifier's input impedance of 10k Ohms and an amplifier's input impedance of 20k Ohms is not small. It's significant, and it'll be magnified by a preamp that has high output impedance somewhere along the frequency spectrum (which is typical of many tube preamps).
Spend just an hour reading John Atkinson's comments in his test measurements of a few tube preamps and a couple amps and you will discover the significance of the preamp/amp impedance matching issue. |
Mapman, what's your budget (stretched...) and what's your power requirement? |
Without commenting on sound, which is a subjective thing, I'd say the amps that best fit your criteria, but would have to be purchased used, would be Bel Canto Ref1000 MK I monoblocks, Belles 350A Reference stereo, or Belles 150A Reference monoblocks. You should know that the Belles amps perform best running balanced, IMO, but the 350A can be run single ended. The 150A Reference monos must be run balanced.
All these amps will drive your speakers extremely well, and they have input impedances of 50k Ohms (Belles 350A Reference) or higher, so they will work well will tube preamps.
The Belles amps run only slightly warm to the touch. The Bel Canto are stone cold.
I'd also recommend used Pass Labs X-250 or Plinius SA-250, but these run warm and are monster amps, so they don't really fit your requirements.
As far as new amps in your price range, I can't think of any at this time. |
Newbee, the sonic differences between a 10k Ohm and a 20k Ohm amp when used with most tube preamps would be applicable to a real live person in a real room provided the person was an audiophile with an audiophile quality system. No question about it. Not just theory. Read Atkinson. He lays it out in plain English. No technical knowledge required.
Although you just tossed out the 10k Ohm impedance spec, it is not an unrealistic number for solid state amps. McCormack amps have an input impedance of 10k Ohms, and in my experience using them (DNA-2, DNA-500), they don't work well with most tube preamps due to the input impedance issue. |
Glad you found that, Almarg. I spent a bit of time Googling it myself without success.
Atkinson states the SP16 should not be used with amplifiers having input impedance "much below 10k Ohm".
So, yes the SP16 appears to work well with most SS amps.
If that's the case, Mapman, you might consider one of the McCormack amps...like a DNA-2 Deluxe or a DNA-500. Check with Foster_9 about his experience using a DNA-500 with his Ohm loudspeakers. I believe he's using one with a VTL linestage. |
Looks like a good call on the A308CR, Mapman. |
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11-07-09: Bob_reynolds
...there are numerous examples in the Stereophile archives where the output impedance of a tubed preamp gets very high in the bass region. Without JA's measurements the consumer is truly in the dark about which amps will mate well with such preamps. Amen to that, Bob. It's a point I've attempted to drill home to whoever will take the suggestion. As much as we sweat the details of cables and electrical outlets, to not consider proper impedance matching between components just doesn't seem rational to me. I'm glad to see that Mapman is attempting to get a good fit.
Bob_reynolds (Threads | Answers) Can I get another Amen! |
...of course, many audiophiles will continue to blame their interconnects and keep spending when their problem is simply a matter of a poor impedance match and choice of components
Shadorne (System | Reviews | Threads | Answers) Tell it! Tell it! Hallelujah! |
