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Question about external crossover with tube preamp

I'm setting up a new 2-channel system, and in my setup, I'm looking to use a tube preamp. I also want to use an external crossover of some kind, so that the sub handles the low frequencies, with the mains handling the higher frequencies. I'll probably cross at around 80 Hz.

My question is this: I know that when matching a tube preamp with a SS power amp (or a SS subwoofer amp), it's important to check that the Zout on the preamp is sufficiently low compared to the Zin on the amp. Im thinking it should be better to connect the preamp directly to the power amp, rather than connecting it to both a power amp and one (or two) sub amps, particularly since the Zin on sub amps can be rather low.

However, it seems like most people are crossing using an active crossover, which goes between the amp and preamp. This requires that the preamp signal go to both the power amp and the sub amp, which I'm trying to avoid for the reason above.

Is it generally a bad idea to use an active crossover with a tube preamp, or is it "okay" for some reason, given the impedance characteristics of typical equipment?
rrolack
Post removed 
martykl
3,578 posts
 
Rrolack,

FWIW,

I use exactly the type of set-up you're describing. A tubed ARC preamp (LS 25) feeds an NHT X-2 active x-over. The NHT high pass out (signals over 75hz) feeds an ARC VT 130SE. The main speakers are usually Ohms, but I also ocassionally rotate in Maggie or Verity speakers.

The low pass out of the X-2 feeds a Velodyne SMS-1 subcontroller which allows for digital room correction and fine tuning of the high cut filter characteristics for the sub's top end roll-off. This signal, in turn, feeds 2 Rythmik 12" subwoofers.

The results have been enormously satisfying in a very tough room and the NHT X-2 has little to no (to my ear, anyway) impact on the main signal path.

As always, YMMV.

Good Luck

Mary
martykl
3,578 posts
 
That sign-off should read:

Good Luck

Marty

(Last I checked, anyway)
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