Tube Preamp/ McCormack Amp impedance matching

Oops! I wasn't thinking too clearly when I wrote the last post. I assume the two subs are on separate channels, so if the two sets of preamp outputs are not separately buffered, they would see 6K in parallel with 10K, or 3.75K on each channel. Still too low for comfort.

If there are separate buffers, each channel of the pair of outputs driving the subs would see 6K, which may also be too low if the preamp output impedance rises significantly above the specified 200 ohms at low frequencies, which it probably does.

Regards,
-- Al

Subs are Earthquake Supervova Mk12IV. I'll see what I can learn on the preamp outputs.

I did some looking, but couldn't find an input impedance spec on the low level inputs of the MKIV's. I think I did see a reference to the MKV's being 6K. So all I can suggest at this point would be to contact Earthquake Sound and ask them, and also to ask VTL if they can tell you what the preamp's output impedance is at the frequency for which it is highest.

Regards,
-- Al

Al, Thanks for everything. I'm now using an ATI MM100 Match Maker between amp and preamp as a work-around of impedance issues and the added subwoofer's impedance. It sounds good so far in the signal chain but I haven't turned on the subs yet.

Emerson -- I'm not sure that is a good solution. According to the MatchMaker specs shown here, the output impedance of its unbalanced outputs is 1500 ohms!

The output impedance of its balanced outputs is very low, but it looks like the transformer it uses to generate the balanced outputs is optimized for a professional-type low impedance load ("600/150 ohms"), and it may not perform at its best if you were to run it into the DNA-500's balanced inputs, which I presume are much higher impedance.

Also, the unbalanced input impedance of the MatchMaker is 10K, no higher than (and in fact the same as) the DNA-500's!

Sorry to be the bearer of bad tidings!

Regards,
-- Al