2. amps-preamps
  3. 165566-22261

PASSIVE SUBWOOFER DRIVEN by a 2 CHANNEL PRE-AMP + MONOBLOCK ?

I’m hoping someone can advise me so a sub question
I have an 18 inch Passive subwoofer , the Wilson Benesch Torus

for some reason the engineers sell it with an external amp/crossover module . Inside is a 200 watt class Ab amp. To add insult to injury, I noted some made in China capacitors . A disgrace at this price point LOL

ive never been game to run it loud because I don’t think the amplifier has enough juice

if I experimented , say , using a stereo preamplifier and a 600 watt bryston monoblock and run my XLR cable from the subwoofer out on my home theatre processor —-> to my all analog stereo pre amplifier then only 1 channel on the preamp is being used . Of course the preamp then connect to my Bryston monoblock via an XLR plug



am I potentially doing damage to my preamp by only using one of its channels ?

200 watts seems a tall order to move an 18 inch cone at 20 hz at 80 decibels . I’ve spoken to several techs who feel most of the made in China subwoofer plate amplifiers are rubbish so I’m trying to avoid class D Chinese amps.

the Torus is a good  sub for 2 channel duties I remember reading it’s not that good for home theatre. Thank you if anyone has input.
wt4158

Showing 2 responses by auxinput

auxinput
2,920 posts
 
No, it will not hurt your preamp if you only use one channel.  However, I don't think you need to use a preamp.  The subwoofer output on your HT Processor should already volume controlled (just like all the other channels on the HT Processor output).  You can connect it directly to the Bryston amp.  Although I think there are be better amps.  The Bryston amps tend to be a bit thin sounding on the bass/midbass.

That being said, it looks like your Wilson Benesch is a sealed sub.  These tend to sound a lot cleaner.  For home theater usage, I like to have a ported/vented sub because they sound thicker and more meatier.  If you want to replace the Wilson, maybe look at a Rythmik vented subwoofer.

If you want a really nice sub amp for cheap, look for a used Emotiva XPR-1 "Gen 1" or "Gen 2" amp.  I have found that these have some of the best bass (especially when you upgrade the fuses).  A Parasound JC1 might be okay, but I don't think they are as good in the bass as the Emotiva.  Alternatively, you can look at one of the higher power Class D amps.
auxinput
2,920 posts
 
Yes, you can adjust the "trim" of the subwoofer output in the HT Processor.  I have never had any problems with some movies having bass/LFE mastered too loud, but if you wanted to put a preamp in the middle, it won't hurt anything.

Also, be aware that most those pro amps (Crown, Behringer, QSC) are fan cooled.  The fans can be relatively loud and will be annoying during movies.  Unless you are putting these amps into a closet or separate room, it may be too much fan noise for your movie experience.  I had a couple older Crown CTS amps and the fan noise got to be too much (almost like hiss coming through the speakers).  The CTS2000 I had did a good job for subwoofer, but the older Emotiva monoblocks were a stronger amp for subwoofer (it didn't matter how loud it was).

Using one channel of a stereo amp is just fine if you want to do this.  Some of these amps, such as the Crown XLS, are Class D amps. 

I would like to put forth another suggestion.  Since you are in Australia, availability of amps is going to be difficult.  I would look at the Nord Acoustics website.  They are in Europe, but ship anywhere.  Look at the "Nord One SE NC1200MB Mono Blocks Single" amp.  These output 400 watts into 8 ohms, but will do up to 1200 watts into a 2 ohm load (which is stable).  It is priced at 1,149 Euro (which is 1,780 Australian dollars).  Contact them and request that it is loaded with the previous generation 8-pin Sparkos SS3602 op amps for the input stage (instead of the SS2590 pro op amps).  These are excellent discrete opamps.  While they don't have the best resolution for high frequencies, they have some of the strongest and fullest bass that I have heard from an op amp (this is mostly due to how the slew rate is handled in the opamp).  I think this solution would be significantly better for your subwoofer than any of the pro amps.
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