Sub connection to CARY SLP-05 preamp

Marty, I use the NHT X2 as well, but strictly as a low pass filter for my 2 JL113s. The low pass also runs through a SVS sub EQ unit before reaching the subs. My mains run at full range as I am a firm believer of keeping any circuitry (in this case an active high pass filter) out of the mains signal path if you can help it.

If I were to try a high pass filter for mains I would get a Marchand instead of using the NHT x2 (which has very limited slope and cross over frequency options), but I confess that part of that decision would be an irrational suspicion of a $400 device in my mains signal path doing high pass filtering (i.e. the NHT x2).

What we seem to agree on not to use the high pass filter of the sub's Xover for your mains.

Marty, take a look at the manual for the Velodyne DD subs. Its descriptions of the RTA/EQ processes are similar to what you have described, but I see absolutely nothing in the manual to suggest that those processes would not occur in exactly the same manner if the sub's inputs are at speaker level, driven from the outputs of the main power amp, compared to the configuration in which the sub's line-level inputs are driven from the outputs of the preamplifier.

For the design to be otherwise would make no sense, IMO. At a conceptual level I envision the design as simply dividing down the speaker-level input signals to line-level amplitudes, and then putting them through exactly the same circuitry that is used to process the line-level inputs.

The only difference between the two configurations, I believe, is that if the speaker-level inputs are used, driven by the main power amp, obviously the sub's high pass outputs cannot be connected into the main power amp's inputs. But we are all agreed that using the sub's high pass outputs is undesirable in most cases anyway.

Best regards,
-- Al

If the DD works like my SMS-1 (and I'm told that it's functionally the same), there's a very versatile (fine control of slope, phase, frequency, output level) line level high cut filter to the sub. There's also a crappy, fixed 80hz, 6db/octave low cut to the mains.

The low passed line level signal undergoes ADC, and is reflected on a video screen by the RTA as a sweep tone is generated. The user then applies up to 8 bands of parametric EQ to flatten response and level match the low pass to the main signal (response is displayed up to 200hz). I can assure you guys that this is a very effective way to ensure seamless "hand-off" from main to sub.

OTOH, if you pass at high level, I assume that you keep the crappy 80hz, 6db low cut to the mains, but...

You lose all of that good high cut control for the sub. Basically, you keep the bad and lose the good - I think.

Marty

More good news: The highcut to the mains ain't great sounding either. I use a separate active NHT X2 x-over unit for rolling off the bass to the mains and take the low pass out of the X2 into the SMS for high cutting the sub. The SMS is out of the main path entirely - a good thing IMHO.

Don't know why my post turned up twice. Strange.

You may well be right Al, I was just guessing. The speaker level may go thru the same processing, but intutively, I reached the opposite conclusion....I thought it unlikely that the speaker level signal would see anything but the high pass.

Maybe someone should put the question to Velodyne.

Marty

Edorr,

I tried a Marchand (used) from a local dealer, but the example I got was too noisy to keep. While looking around for a replacement, I tried the NHT on a money back trial basis and ended up keeping it.

Marty