High Current SS amps with input impedance = 200K


I'm looking to identify amps like this that would match optimally to an Audio Research sp16 tube pre-amp with output impedance of ~ 20K?
128x128mapman

Showing 7 responses by newbee

FWIW I find it hard to believe that an ARC pre amp has an output impedence of 20K. 260 perhaps, with a recommendation from ARC that the amp have an input impedence of 20K.

Just a WAG - I didn't bother to research it, I'll leave that up to you. :-)
Mapman, Bob may be 'right' as Tvad sez, but the ratio is way beyond any nominal ratio you see bantered around like 10 to 1 for example. In this case it would be very close to 80 to 1.

Personally I'd tend to trust ARC when it sez a 20K imput impedence would be adequate (I actually did that without regret) and not get my panties in a knot over what the difference would be between say 20K and 47K or even 100K. I'd even take bets that in this instance even Bob couldn't tell the difference if he was listening with a stethoscope. 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.

Personally I'd believe ARC. I'd even go so far as to think that their recommendation would be conservative and act accordingly, spending the copious amount of time necessary to solve these issues to insuring that the amps output impedence was a good match for the speakers to be used, to finding the right tubes to flesh out the pre-amp's tonal issues when matching it with any particular amp, or just sitting back and listening to some good music.

But hey, thats just me. I'm not very anal about all of these techie issues. :-)
Tvad, Note I said no difference at 20K or above, but I did add the words 'unlikely' and 'meaningful' to the reference to 10K. To me at least it probably wouldn't be 'meaningful'. I draw this assumption from my personal experience using ARC stuff and assorted SS and tubed amps with input impedances between 10K and 100K. I get far more wound up working out amp output and speaker impedence matching issues (as I know you do as well).

BTW, Tvad, have you actually heard the SP16 connected with a 10K amp AND an identical amp differing only in that the impedence value was increased to 20K. Im unaware of any such amps though. I think if we could find a techie who could set up such a demo by altering the output impedence of some amp in some way without otherewise changing the signal, we might then, and I think only then, know if there was a difference, meaningful or not.

But its fun thinking about all of the issues anyway. :-)
Tvad, I'm sure I could hear the difference. That part would be a walk in the park. But I'm not so sure that I could connect the difference to the difference in impedence values as opposed to the amps design or how it interfaces with the speakers.

For Mapman, whose post follows. FWIW IMHO, the differences which may occur between the small differences, or deviation from optimum values, between amp and pre-amp that we are talking about (I'm NOT talking about gross mismatches, or even medium mis-matches) are absolutely dwarfed by the output capabilities as well as the tonal signature of the amp and the impedence curve of the speakers. But you have probably already figured out that that is my opinion. :-)

BTW, if you are looking for high power, high quality power ss amps, I'd recommend that you look at some vintage stuff, especially stuff made by Nelson Pass when he ran Threshold, especially the SA or S series stuff. Even if you had to have some recapped because of age they would still be a hell of a deal. If I ever went back to SS that is the first place I would go.
Mapman, Note that I deleted the post you are responding to. Sorry about that. I was really responding to Tvads observations and was not at all pleased about what I was saying especially as it applied to you. I had already communicated all I could really offer to you in previous posts. And I saw no reason to continue the correspondence with Tvad although he is so serious I must admit that I do, sometimes, enjoy rocking his boat. He is a good guy and means well.

But, FWIW, if you can accept the accuracy of ARC's recomendations about amp matching with that pre amp, restricting your search for an amp based upon a desire for higher input impedence will not add to the performance of the amp/pre-amp combo. If the car takes regular gas and the tank is full, that is as good as it gets.

Hope you find the right amp for your Ohms.
Almarg sez "Amen from me too, of course"

To the profusion of Amens I would add that Almarg should get a few hozzanah's and more than one Amen for fleshing out the actual detail and providing a concise answer to the OP's concerns regarding the use of the SP16 with SS amps and not joining the crowd wandering thru the desert firing at phantom snakes from the hip.

Almarg, you are a model for folks who want to help others asking questions here. You have intelligence, knowledge, and a generous interest in helping others that makes you stand out high above the crowd. The folks here are in good hands when you have the opportunity to join in threads.

You are an AGon treasure. !!!!!!
Hi Bob, Please consider my posts in this context - I was not trying to do anything more than provide a 'simple' answer to the OP's question without getting technical nor doing his research for him. That is a methodology I have used professionally as well as in these forums. In retrospect I probably didn't do it well here. It didn't work out well did it! :-)

As Al pointed out Stereophile had reviews which specifically addressed this particular unit, information that was available to all who cared to read it. I knew about them as well and had read them when they were published. In the future I will try to emulate Al more and simply refer folks to the source and avoid adding an interpertation and describe how it would actually effect his situation (unless he were to ask of course). That will be more helpful to the poster's understanding, perhaps stimulate his curiosity and encourge further research into the issue, but as importantly, avoid potential unpleasantry between the responding posters.

Hope you guys all have a nice day...............