[dallaire1]

Okay, got a moment to test for clipping on the M33 at the "pre-outs" full tilt main volume at 40Hz and NO clipping at pre amp outputs.

[dallaire1]

The voltage is lower than expected on the scope coming out of the pre amp out's ? Subwoofer outs, put out 1V but pre amp outs should be 3.9V. Input to the pre amp inputs on M33 says-( LINE IN, Input Sensitivity 280mV(ref 500mVout, Volume maximum))  (Maximum input level 2Vrms/8Vrms (low sensitivity mode)).

my computer soundcard clips right after the level shown on my DDM.

[dallaire1]

Those that can't see the reading, it's 15.3mV on the SC right before clipping it's output. perhaps I need to dig out an old interface that's capable of delivering more input voltage to the pre amp inputs.

[EdwardT]

3.9V is almost three times normal +4dbu line level out in the analog world. 0 dbu is 0.77volts, which is where the meter reads before going into the red. Seems pretty hot, but I’ve been wrong before. All the same that’s like a +14 dbu output which is massive distortion in the analog world. FWIW my Vidar is rated to achieve full output with a tad over 1.2v input, a point I’ve never reached but I expect would have the two monoblocks driving our XLS-S towers puking speaker parts across the room.

[77SunsetStrip]

Did you look at the subwoofer out waveform?  Isn't that what should be sent to the subwoofer amps?

[Tyson]

Don't use the subwoofer out.  Use RCA Y-splitters on your main 2 channel RCA outputs. 

[dallaire1]

That was the pre amp outputs, not the sub pre out's. I've already tested the output at clipping on the sub amp leads at 40Hz. Sub amp clipped at 18 volts, using my pre amp outputs.

[dallaire1]

I'm running splitters on the sub amps.

[dallaire1]

This voltage reading is without splitter adapter.

[EdwardT]

I don’t understand where the “preamp should be 3.9v” comes from. 3.9v will drive 4 ohm speakers close to three watts, that’s a speaker level output.
https://www.prosoundtraining.com/2018/08/09/audio-power-amplifier-maximum-input-voltage/

[dallaire1]

That's simply what NAD says is the voltage output rms at the pre amp outputs.

[EdwardT]

Ok then, it’s from the maker. All the same it’s enough to drive your main speakers to 90dB or so. The 1 volt from the sub out is a proper level to drive the plate amp to full output; there’s just not enough documentation from Rythmik so the only thing I can do is guess and I don’t know enough about their “servo” system to move forward. I'd guess everything about the rear firing speaker would be out of phase, certainly the speaker leads but likely the servo leads, too, since they’re reading the magnetic field at the voice coil. Or it could just be bad amps. An independent music source might rule that out, even a dusty iPod jacked right into the sub, but that’s your call.
I did go to the NAD site, read the specs and look at the amp. Those double speaker outputs look perfect for driving a plate amp thru the high level in.

[dallaire1]

I didn't have any luck with the plate amp passing the high level signal to the main speakers at all.

[morganc]

Don't use the subwoofer out.  Use RCA Y-splitters on your main 2 channel RCA outputs.

This is how I have mine set up as well. Split RCA from main line out into the RCA in on the plate amp.  If you’re not doing that, why not give it a try? 

[EdwardT]

I didn't have any luck with the plate amp passing the high level signal to the main speakers at all.

I meant to duplicate the main output, those spade connectors to the Ms and a banana plug from the same post to the plate amp high level in. After I thought about it the amp might not like driving no speaker load from the B main outputs; I don’t know the amp so it’s a WAG. My guess is that the maker's intention is to jump off the speaker posts of the main speaker but tube connectors don’t offer that option so it would need to come from the amp posts.

[OrangeAgent]

I didn't have any luck with the plate amp passing the high level signal to the main speakers at all.

Looking at the way you had it wired, you had the mains coming off the right channel line in, and with NAD feeding the left channel line in. It isnt a pass through, you are supposed to run another wire to the plate so its in parallel. It also looks like the crossover dip switch is in the middle, which is the AVR/LFE setting for an external crossover. If you were using the line outs, and havent changed that setting since you were using the sub outs, then you are sending a hot full range signal unfiltered to the plate which I would imagine it would not like.

[dallaire1]

Thanks for pointing that out. I have never used the speaker level inputs before and no info on Brian's quick guide for this specifically. It's all now reconfigured with treatment in a different room now.

[Tyson]

Did you get the amp back from Danny already?  What did he say?

[dallaire1]

Funny you brought that up. I was just going to check my tracking number. Danny should have gotten the delivery on 11/23 tentatively?

[dallaire1]

UPS tracking says delivered on 11/21, got there earlier than expected.