subwoofer or bass unit for 80s rogers ls3/5a 15ohm

jasonsouza77

jasonsouza77

New Member
hi everyone, was thinking of adding a sub to the chain. I'm on a budget and am considering one of the polk subs. I'm using naim 140 + 72. it only has channels for one pair of speakers. I'm just curious. if I purchase a powered sub, and connect the speakers and amp to it via speaker in/out, will the ls3/5's still be powered by the naim? or is it powered by the sub? will the sub lessen the bass load from the ls3/5's? this is the sub ive been looking at :)
https://www.polkaudio.com/products/psw108
thanks so much for reading this n happy holidays to one and all :)
 
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The LS3/5s will still be powered by the Naim. Using speaker-level connections is the way to go, IMO. I can't tell for sure from the limited specs, but the Polk sub does not seem to have a high-pass filter, so the mains will still receive a full-range signal. This is not necessarily a bad thing, IMO, as it helps with blending. Try setting the low-pass filter at the Roger's -3dB down frequency for starters. You don't want the sub adding to the Roger's mid-bass bump, just filling in the lowest frequencies.

Merry Christmas and welcome to AK!

:)
 
back in the day, a bi-amp system with a LS3/5A used a cross over frequency of about 120Hz
to allow or bypass that famous mid-bass bump.

depending on the sub: 1) the LS3/5A may still get a full range signal, 2) the sub gets a full range
signal and depending on its innards may or may not suppress the upper frequencies
3) the sub may not be adjustable for crossover bass. so the combined units may have both
sets outputting bass signals and one may be louder than the other since there's no bass volume
control on the LS3/5A. also if the sub doesn't attenuate the highs then again both may compete.

all depends on that sub and its control over signals coming in and (potentially) out.

but if it all complements each other, then enjoy the music.
 
sqlsavior said:
The LS3/5s will still be powered by the Naim. Using speaker-level connections is the way to go, IMO. I can't tell for sure from the limited specs, but the Polk sub does not seem to have a high-pass filter, so the mains will still receive a full-range signal. This is not necessarily a bad thing, IMO, as it helps with blending. Try setting the low-pass filter at the Roger's -3dB down frequency for starters. You don't want the sub adding to the Roger's mid-bass bump, just filling in the lowest frequencies.

Merry Christmas and welcome to AK!

:)
Click to expand...
merry xmas to you and family sqlsavior. yes I think it only has a low pass filter. that means using speaker level in/outs, the naim still powers the ls3/5a while the sub will be self powered on its own. hmm what does the low pass filter? will it remove the bass load from the ls3/5a? thank you again for your response. truly appreciate it
 
Low-pass means low frequencies are passed (to the sub) while high frequencies are not. A high-pass filter (not included) would keep lows out of the mains; the low-pass keeps highs out of the sub.

With speaker-level inputs, a high-impedance analog circuit receives a tiny fraction of the Naim's output, and amplifies it, without the Naim or the speakers even knowing that it's there.
 
I understand what you want to do, to improve your system, and I am familiar with the Rodger's wonderful sound. The Polk you are looking at is just not very good. A top quality sub can be very expensive, but a cheap one will not fill out what you are missing from your Rodger's. The newer Polk stuff doesn't compare to the older stuff they made. If you could find a Polk PSW 404 10" you would find it to be a good match for your speakers, and it is quite small. It does have a 200 watt Bash amp in it and it weighs 45#. Pawn shops will let you take them home and return them if you don't like them, but check you local policy. I picked up my 404 for $50, and I love it.
 
Dayton Audio from Parts Express is your friend when it comes to inexpensive subs, the Dayton 1200 a 12" sub sells for around $150 now I believe, but often goes on sale for less. It's front firing which I prefer, ymmv.

I see Parts Express is currently selling factory refurbished units for $69, at that price I suggest getting two.

My mistake, it's the B101, their 10" sub that's going for $69, still a hell of a deal and the Dr says take two and call me in the morning.
 
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