NAD352/ Wharfedale SW150 wiring advice

[benr]

Hi all

I'm sure you get loads of newbies asking the same questions over and over - I've had a look through this forum and didn't see anything that helped, but apologies if I'm covering well-trod ground, and for my basic knowledge.

I have a mid-budget setup and am looking to add a subwoofer. I had some connection questions, hope somebody could take a minute to help.

My setup is a NAD352 amp and B&W 602 S3 speakers. It sounds great as the speakers have impressive low frequency response, but I'd like to add a bit more oomph and crispness to the lower frequencies, hence the sub.

The amp has no sub out, but it does have two pre-outs (I can't post an image of it as I don't have enough posts to my name).

The sub I have selected is the Wharfedale Sw150, which seems to be a really good budget option (~$200 here in London) and I like the way it sounds. The setup is in a small room so I don't need anything more powerful - just something to round out the bass more than anything. The sub has two speaker level inputs, two line level inputs and two line level outputs.

My question is how best to connect the sub. I've read around a fair bit and have a pretty good general idea, just wondering what you guys think the best approach would be.

My two options are:

1) Split the Pre-out2/Main-in connection on the amp, and connect amp Pre-out to sub Line-in, sub Line-out to amp Main-in for both channels. As I understand it, this will let me control the frequencies that the front speakers will handle using the crossover on the sub (is that correct?)

2) Use Pre-out1 on the amp, connected directly to line-in on the sub. This should allow the front speakers to accept the full frequency range, and I can adjust the sub crossover until it sounds good.

Questions:

- Does setup 1 cut the lower frequencies from the feed to the front speakers? Is this generally a good thing?

- In 2, the Pre-out1 on the NAD352 is stereo so I can only achieve this using a stereo connection - or can I use a mono sub lead from only one of the pre-outs to one of the line-ins? Threads elsewhere on this forum advise against Y-splitting.

- Do both 1 and 2 allow the sub volume and tone to be controlled directly from the amp?

- Would a standard stereo auxiliary cable be suitable (it's going to need to be long - 15ft or so)? Because I can't find a stereo sub cable and I don't especially want to spend double if I don't have to.

Many thanks,
Ben

 

[ski2xblack]

Hola benr-

I've got that amp in a 2.1 setup. I've tried it each and every way, including w/ active crossovers. Currently it is driving some small sealed monitors directly, relying on the speakers inherent roll-off, with the second set of pre-outs feeding subs a line level signal. I'll try to answer your questions...

Hi all...

Questions:

- Does setup 1 cut the lower frequencies from the feed to the front speakers? Is this generally a good thing?

The line outs on that sub are most likely unfiltered, usually intended to feed more subs. I don't know for sure regarding that Wharfedale, but chances are it has no high-pass filtering capability.

It is generally a good thing to high-pass your mains, but without an active crossover you won't have that option. Is it necessary? Not really, but there are gains to be had by doing so (better allocation of amp power, better dynamics, reduced risk to speakers...). Since those B&W's are ported, I thought I should mention that I've had better luck blending sealed mains with my sub. If it doesn't cause them to roll off objectionably high, you may try plugging the ports (thus losing 1/2 octave or so of extension in exchange for a little wider safety margin). I would consider 80hz to be highest acceptable minimum; if you need to cross your sub higher than that you could be able to localize it.

- In 2, the Pre-out1 on the NAD352 is stereo so I can only achieve this using a stereo connection - or can I use a mono sub lead from only one of the pre-outs to one of the line-ins? Threads elsewhere on this forum advise against Y-splitting.

The pre-outs are stereo, so connect both to your solo sub. Just use whatever interconnect is handy, no need for a y-splitter. It's ok to use y-splitters to divvy up an output to several amps, for example, but you're talking about blending L and R into one here; let your sub do that. You'll have the chance to run stereo subs down the line if you want, in which case each one would only be fed it's corresponding channel.

Twin subs rule, by the way.

- Do both 1 and 2 allow the sub volume and tone to be controlled directly from the amp?

Both sets of pre-outs are controlled by the volume control. Only pre-out 2 on the NAD is independantly variable, and you have to manually change output level on the back of the unit. I use the variable outs to feed my sub as it gives a much better way to calibrate sub level than the gain on the sub itself, which is way too easy to over-do. Set the gain on your sub slightly hot relative to the main speakers, and use the variable out trim it down in fine increments.

You will have to adjust the sub's low pass filter separately, on the sub itself.

- Would a standard stereo auxiliary cable be suitable (it's going to need to be long - 15ft or so)? Because I can't find a stereo sub cable and I don't especially want to spend double if I don't have to.

Many thanks,
Ben

Yes...while you probably want a shielded interconnect for such a long run, don't waste money on boutique cables. Try Blue Jeans or Monoprice online, or your local electronics repair/wholesaler/hardware store. The NAD's pre section can push enough juice that such a run is absolutely no problem.

 

[benr]

Hi ski2x

Thanks so much for the detailed response. I've just spent an hour on google trying to understand it , but it's very useful indeed.

The line outs on that sub are most likely unfiltered, usually intended to feed more subs. I don't know for sure regarding that Wharfedale, but chances are it has no high-pass filtering capability.

It is generally a good thing to high-pass your mains, but without an active crossover you won't have that option.

In that case, there's no advantage to running Pre-out -> Sub -> Main in over just Pre-out -> Sub, is there? If the feed coming out of the sub is unfiltered (I think you're right on that one), then all I'd be doing would be exposing the preamp feed to an extra 30ft of cabling. So my scenario 2) would be better than 1), in this case, right?

If it doesn't cause them to roll off objectionably high, you may try plugging the ports (thus losing 1/2 octave or so of extension in exchange for a little wider safety margin).

Very interesting idea - I will try this if the blending is proving tricky.

Twin subs rule, by the way.

Hehe, you're getting me tempted, and I'll have some serious explaining to do to the wife if I come home with two of the damn things!

Both sets of pre-outs are controlled by the volume control. Only pre-out 2 on the NAD is independantly variable, and you have to manually change output level on the back of the unit. I use the variable outs to feed my sub as it gives a much better way to calibrate sub level than the gain on the sub itself, which is way too easy to over-do.

While I agree this is a good approach, I don't see any Pre-out2 output level adjuster on the back of my amp. Perhaps I'm being dense. I still can't post links, but if you google for "site:superfi.co.uk c352" the first link contains a high-res image of the back of the 352, which is the same as mine. Could you please give me a little more info on how I would go about manually adjusting the Pre-out2 level?

Thanks again for the response.

 

[ski2xblack]

Hi ski2x

Thanks so much for the detailed response. I've just spent an hour on google trying to understand it , but it's very useful indeed.



In that case, there's no advantage to running Pre-out -> Sub -> Main in over just Pre-out -> Sub, is there? If the feed coming out of the sub is unfiltered (I think you're right on that one), then all I'd be doing would be exposing the preamp feed to an extra 30ft of cabling. So my scenario 2) would be better than 1), in this case, right?

Yes, scenario 2 would be better for exactly the reason you state.

Very interesting idea - I will try this if the blending is proving tricky.

Don't be afraid to experiment a little. I have some ported Missions that just never blended well until I did this. I suspect it was due to the gentler roll-off of a sealed enclosure, and no ports/drivers working against themselves below their rated flat response (where the cones and air in the port move excessively but don't contribute to sound pressure levels because they are out of phase-no sense having that noise compete with your sub). If you really crank it, an active crossover would be advisable to prevent your mains from seeing high power bass signals; if you are more modest in your spl's, you probably don't need one.

Hehe, you're getting me tempted, and I'll have some serious explaining to do to the wife if I come home with two of the damn things!

Well, this is an addiction rather than a hobby. Hopefully your old lady will understand.

While I agree this is a good approach, I don't see any Pre-out2 output level adjuster on the back of my amp. Perhaps I'm being dense. I still can't post links, but if you google for "site:superfi.co.uk c352" the first link contains a high-res image of the back of the 352, which is the same as mine. Could you please give me a little more info on how I would go about manually adjusting the Pre-out2 level?

Thanks again for the response.

You're correct...my bad, I have the 372, which does have this feature. You are limited to the gain on your sub. Hopefully the gain control on your Wharfedale is more precise than that on my sub, but even if it's not, you should still have no trouble calibrating levels.