Need help from the gurus for hooking up a modern sub with LFE input with an old school integrated NAD amp

[The Chukker]

Ok guys, I'm trying to upgrade my garage gear.
For amplification I'm running an old school NAD 302 in 4 ohm mode.
Panasonic DMP BD-30 as a source using only the analog outs (again, not sure if I should run only the left and right analog outputs or use the analog subwoofer out as well).
Mains are Dayton MK442 (mounted vertically)
And here's the kicker: I want to add a BIC F12 Sub.
The NAD 302 doesn't come with a dedicated Sub out.
It has Pre-outs with jumpers to the Main In as shown:

A quick search of the NAD website is somewhat confusing for me:

And here's another shot of the rear of the amp:

This is for two channel music in the garage, no 'home theater' use -- although I see occasional use of the .1 on a music dvd.
I was planning on using a male sub y-splitter that would sum the left and right pre-out with the other end being female. And then running a standard sub cable from the splitter to the sub.
But that doesn't seem to be exactly what the NAD instructions are (which again, confuse me a bit).
Some super specific pointers would be nice here.
Thanks in advance!!

 

[lovinthehd]

The splitter won't properly sum the l/r to mono. I see this sub doesn't have both the L/R rca inputs, tho so the alternative would be to use the high level inputs on the sub (assume the sub can still sum to mono that way).

 

[The Chukker]

The splitter won't properly sum the l/r to mono. I see this sub doesn't have both the L/R rca inputs, tho so the alternative would be to use the high level inputs on the sub (assume the sub can still sum to mono that way).

I haven't purchased the sub yet for the garage, so will one with both a dedicated left and right analog input sum the signal to mono properly?
Also, I'm having a hard time visualizing what is needed as per NAD's instructions.
Can you make sense of it?

 

[The Chukker]

The splitter won't properly sum the l/r to mono. I see this sub doesn't have both the L/R rca inputs, tho so the alternative would be to use the high level inputs on the sub (assume the sub can still sum to mono that way).

Also, I have an extra Definitive Technology ProSub 80 laying around which DOES and dedicated left and right line level inputs. Does that solve my issue?
Just connect each pre-out on the NAD to the respective input on the sub and the sub will sum the signal to mono properly?
On that note, does each need to be a dedicated subwoofer cable or will a standard RCA cable work in this scenario?

 

[lovinthehd]

I haven't purchased the sub yet for the garage, so will one with both a dedicated left and right analog input sum the signal to mono properly?
Also, I'm having a hard time visualizing what is needed as per NAD's instructions.
Can you make sense of it?

When I first saw your post that's what I was going to suggest (i.e. what Nad mentions) thinking the F12 had the usual L/R rca inputs (and ability to sum to mono). Just split the signal on the pre-out, one of each going to main, one of each to the sub. Subwoofer cable is more an application than a specific type of coax cable, altho better shielding for a long run isn't a bad way to go. You could still use the F12 with high level (speaker wire) inputs, too, or pick another sub.

 

[lovinthehd]

I haven't purchased the sub yet for the garage, so will one with both a dedicated left and right analog input sum the signal to mono properly?
Also, I'm having a hard time visualizing what is needed as per NAD's instructions.
Can you make sense of it?

Generally that's what a sub will do with both L/R inputs. It's pretty easy to visualize with a pair of y-splitters and two long rca cables....

 

[Steve81]

Also, I'm having a hard time visualizing what is needed as per NAD's instructions.
Can you make sense of it?

You need two splitters, one from the left preout to the left main in + left subwoofer input, and another for the right preout to the right main in + right subwoofer input.

 

[The Chukker]

Generally that's what a sub will do with both L/R inputs. It's pretty easy to visualize with a pair of y-splitters and two long rca cables....

So two of these bad mamajamas here one coming out of pre out L and one coming out of pre out R:

^with an rca cable back into the respective Main In on the NAD amp and the other out to the respective input on the sub.
Is that correct?

 

[Steve81]

Is that correct?

Yup. One other alternative (besides using high level inputs on the sub as lovin mentioned) is to get a sub with filtered line level outputs like this:

Then you'd just run the preouts to the line level inputs on the sub, and the line outputs in the sub to the main inputs on the NAD. That way you'd get some semblance of bass management to protect the Daytons from low frequency content.

 

[The Chukker]

Yup. One other alternative (besides using high level inputs on the sub as lovin mentioned) is to get a sub with filtered line level outputs like this:
View attachment 28959
Then you'd just run the preouts to the line level inputs on the sub, and the line outputs in the sub to the main inputs on the NAD. That way you'd get some semblance of bass management to protect the Daytons from low frequency content.

The MK442's reach down below their advertised 60hz, and the NAD runs in 4 ohm mode so they'll at least have enough headroom to boogie.
With the ceilings in the garage being so high the HSU VTF-2 is looking quite good right now.

 

[lovinthehd]

The MK442's reach down below their advertised 60hz, and the NAD runs in 4 ohm mode so they'll at least have enough headroom to boogie.
With the ceilings in the garage being so high the HSU VTF-2 is looking quite good right now.

What do you mean your Nad runs in 4 ohm mode? This might be interesting to you https://www.audioholics.com/audio-amplifier/impedance-selector-switch-1

 

[The Chukker]

What do you mean your Nad runs in 4 ohm mode? This might be interesting to you https://www.audioholics.com/audio-amplifier/impedance-selector-switch-1

yessir

 

[The Chukker]

What do you mean your Nad runs in 4 ohm mode? This might be interesting to you https://www.audioholics.com/audio-amplifier/impedance-selector-switch-1

I learn something new every day. Now, where's my damn screwdriver?

 

[The Chukker]

Yup. One other alternative (besides using high level inputs on the sub as lovin mentioned) is to get a sub with filtered line level outputs like this:
View attachment 28959
Then you'd just run the preouts to the line level inputs on the sub, and the line outputs in the sub to the main inputs on the NAD. That way you'd get some semblance of bass management to protect the Daytons from low frequency content.

I've decided to go with the RSL Speedwoofer 10S. It ships for $399 all in and should sound amazing with music.
It has all the features you noted above, including low level stereo in, and low level stereo out -- and I can use the internal crossover as you alluded to above giving me that peace of mind with the MK442's
Should sound nice and tight and pretty darn amazing in the garage when I'm working on the cars.
PLUS it saves me hassle of buying splitters et al.
Thanks for your help Steve O

https://rslspeakers.com/speedwoofer10s/

 

[Steve81]

I've decided to go with the RSL Speedwoofer 10S. It ships for $399 all in and should sound amazing with music.
It has all the features you noted above, including low level stereo in, and low level stereo out -- and I can use the internal crossover as you alluded to above giving me that peace of mind with the MK442's

High Chuck,

Perusing the manual for the Speedwoofer, it doesn't look like the line level outputs are filtered. Instead, they recommend an in line crossover like this to connect at the main-ins on the amp:
https://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-70-hz-high-pass-rca--266-272

 

[The Chukker]

High Chuck,

Perusing the manual for the Speedwoofer, it doesn't look like the line level outputs are filtered. Instead, they recommend an in line crossover like this to connect at the main-ins on the amp:
https://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-70-hz-high-pass-rca--266-272

So it is a 12db slope (roll off) below 70hz rather than eliminating low frequency information altogether?

 

[The Chukker]

The reviews by users on PE are not too promising, some saying the crossover was driven much higher as evidenced by calibration software (110Hz and 140Hz) respectively.
I would almost rather not run them at all and adjust the bass/treble on the front of the NAD.
I guess the switch on the sub for external crossover/internal crossover is only for the high level connects eh?

 

[The Chukker]

High Chuck,

Perusing the manual for the Speedwoofer, it doesn't look like the line level outputs are filtered.

Am I missing something here?

 

[Steve81]

I guess the switch on the sub for external crossover/internal crossover is only for the high level connects eh?

Seems to just control the low pass filter on the subwoofer itself.

Am I missing something here?

It's on the next page:

Caution: Protect Your Speakers
In a normal home theater system, the A/V receiver or processor protects the other speakers in
the system by filtering off the bass when you set the crossover frequencies. This is especially
important when your other speakers are smaller and not designed to handle low bass frequencies.
In the above 3 methods of connecting your subwoofer in a stereo system, your amplifier
will deliver all of the bass to your other speakers. If the speakers are small, damage could result
if played at a very loud volume. However, you can protect your smaller speakers by using
external inline filters to reduce the bass frequencies going to your speakers. These filters plug
inline with your RCA cables. If you would like to get a set of these filters, please contact us.

 

[The Chukker]

Odd, the 50Hz units are much higher reviewed, and since the MK442's do dip down into the upper 40's this may be the solution I need.
https://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-50-hz-high-pass-rca--266-270