Amplifier impedance issues?

[ropeboy88]

Good Morning,
I am currently thinking of buying a new pre amp to go with my ATCSCM50a active speakers. From what I've read the Eastern Electric Minimax sounds like it might be a good match sonically but I am concerned over impedance problems. The output impedance of the pre is 1.5 Kohms and the input impedance of my actives is <10 kohms. I would also like to run long (say 8m) interconnect cables between the pre and the speakers. Does anybody have any comments on these issues. As an aside I have also been thinking about an EAR 802, anyone that can shed some light on its sonic character as I have struggled to find much on the internet?
Many thanks.

[John Caswell]

Hi Ropeboy,
The impedances given will be fine. The technique is always to drive from a low impedance to a high one so 1K5 > 10K is fine. Generally the lower the drive source impedance the better. For instance the PreIII has an output impedance of 10R and the capability of balanced outputs so will drive very long interconnects comfortably and I would giver this pre amp a good look if I were you.
I am not familiar with the ATC SMC50s, do they have a balanced input? If so I would definitely use that option, especially as you are looking at long interconnects, and look for a preamp with balanced outputs and use good quality twin screened interconnect cable of the type supplied by World Design.

John - Dr John

[Richard]

Imho, I wouldn't buy either and sense you have your doubts too. 1.5k into less than 10k using 8m interconnects is not good and may well result in audible losses. The usual pre for those speakers will be high quality ss with low output impedance. A ratio of x10 is generally held as minimum using short interconnects and x20 a better bet.

Two things (amongst others) are important in separating so-so gear and stuff that rises above the median. Feedback and impedance matching. Solid state will often be low impedance but valves may struggle to give that. Valves use cathode follower output, resulting in 1-2k, or go to op TXs giving just a few ohms but at far greater cost. One can swap boxes around (especially if valves are mixed with ss) for a long time looking to chance upon a happy combination if this is not understood.

The Eastern will be cathode follower with that output impedance and the 802 may be similar. I've used cathode follower preamps inc Ear 834L and they work but sound lifeless. Keep interconnects very short and low capacitance and forget about them driving long cables. I think the more expensive Ear 864 uses output transformers (not heard it), or go to WD Pre3 for a fraction of the price (if you can't build it get the ready built version for a little more).

Rich