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Tubes on top and Class D on the bottom

I am curious about an experiment involving tubes for the tweeter midrange and Class D Bel Canto M300s) on the woofers of my Von Schweikert VR-4JRs. After reading about the little Miniwatt N3, which is an integrated amp, can I use it for level matching? I would be feeding a signal from a Modwright SWL 9.0 tubes pre-amp to both amps. Or, would I blow everything up in the process, like Mister Wizard?
tgrisham
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almarg
9,670 posts
 
Not a good idea.

First, you won't be able to match the gains with the volume control on the N3 because, I'm pretty certain, the gain of the M300 is greater than the gain of the N3 when the N3's volume control is set at max.

Second and more importantly, if you could match the gains, keep in mind that that would mean that when a given voltage level is fed into the amps, it would produce a voltage at the output of each amp that is the same as the voltage at the output of the other amp. Therefore, if you attempted to utilize any significant fraction of the M300's power capability, you would undoubtedly drive the output of the N3 way beyond its clipping point.

In other words, in a passively bi-amp'd arrangement that uses different model amps for the bottom and for the top, the voltage swing capability of the lower powered amp will typically limit how of the higher powered amp's capability can be utilized. If you go beyond that point, the mid/hi drivers of the speaker will receive a severely distorted signal.

Best regards,
-- Al
mfsoa
76 posts
 
I say go for it! I did the same w/ my VR4-JRs, using a VAC tube amp on top and a Digital Amplifier Co. Cherry amp for the bass. If the gains are close enough, it works great. Tried a monster Carver SS amp on the bass but it was dramatically outperformed by the Cherry. (Tip - it can help to evaluate each amp, either the bass amp or the M/T amp, by disconnecting the other amp - for example listening to only the bass cabinets w/ no M/T is very revealing!)

Turns out the Cherry sounded so good full-range (along w/ heat/ tube life considerations) I sold the VAC and now run a Cherry JR full range.
tgrisham OP
1,291 posts
 
Al-thanks for the info. It seems the only safe way is to buy a separate tube power amp for the top and use a PVC on one or the other to level match. Correct?

Mfsoa, I have heard that tubes on top and SS on the bottom is a good match. I want to take full advantage of the bass which will go down to 20 Hz in my room and SS can do that.

Its not that I am unhappy with the BC amps, just interested in experimenting for fun. Thanks to both of you.
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