Sub connection to CARY SLP-05 preamp

I don't know how the DD-12 works, but I presume it has a separe line level input and speaker level input and the EQ and Xover can only be applied to the line level input - I could be completely wrong on this. If this is the case you cannot use the speaker level input, because your subs would run on a full range signal, which would be a complete mess with your mains.

I also would personally never run my mains with a high pass signal out of a relatively low grade Xover build into the sub. (not to mention long runs of cabling from preamp to cabling back into your main power amp.

So to me the only option would be to split the line level signal from the preamp and run parallel into mains and sub, applying EQ in the sub and using the sub xover for low pass filtering. If there are no impedance issues with this approach this would be preferable IMO. Of course, you run your mains at full range in this setup. In my (limited) experience this is not an issue, as long as you use a low crossover point for your subs.

I could be wrong here but I believe the Xover works on the line level input. This would make this a complete non-starter, since you need to apply a low pass filter.

I would feel pretty certain that the sub low pass filters its speaker-level inputs no differently than it does with its line-level inputs, aside from providing different gains for the two paths.

Regards,
-- Al

Could very well be. Lack of EQ would still be an issue, but may be even EQ works on speaker level inputs as well.

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.

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.