Adding a sub to a 2ch system

[Andrein]

Hi,

Trying to help my friend who despite having a good 2ch system is not happy with the bass. He would like to add a small sub (his room is quite small).

His system - PC with JRiver, some external DAC, Benchmark preamp, Benchmark amp, KEF R3. I told him this pair of Benchmark amps is overkill for what he wants, good AVR would be enough, but... Anyway, what is the best way to connect a sub? Preamp does not have preouts. Also, how to get crossovers, delays and volumes sorted?

 

[lovinthehd]

I don't see much sense in tossing Benchmark stuff for an avr, altho the avr will have bass management. That the LA4 he has? It has a mono pre-amp output for a sub, altho no indication of any bass management. You could just use the low pass filter on a sub to "blend" with the speakers.

 

[Kingnoob]

Hi,

Trying to help my friend who despite having a good 2ch system is not happy with the bass. He would like to add a small sub (his room is quite small).

His system - PC with JRiver, some external DAC, Benchmark preamp, Benchmark amp, KEF R3. I told him this pair of Benchmark amps is overkill for what he wants, good AVR would be enough, but... Anyway, what is the best way to connect a sub? Preamp does not have preouts. Also, how to get crossovers, delays and volumes sorted?

Doesn’t really matter which amp you use without a sub you’re not getting much bass out of those r3 s.
An avr would probably work better then separates, little late for that now.

 

[Andrein]

I don't see much sense in tossing Benchmark stuff for an avr, altho the avr will have bass management. That the LA4 he has? It has a mono pre-amp output for a sub, altho no indication of any bass management. You could just use the low pass filter on a sub to "blend" with the speakers.

Yes, LA4. But that low pass filter will affect only sub, right? There will be a hike around that frequency in the overal chart? My point for avr was that he would get bass management and other stuff and for his small room he does not need amplifier (which is just 100w btw, less than many avrs).

 

[lovinthehd]

Yes, LA4. But that low pass filter will affect only sub, right? There will be a hike around that frequency in the overal chart? My point for avr was that he would get bass management and other stuff and for his small room he does not need amplifier (which is just 100w btw, less than many avrs).

If the low pass filter is on the sub, yes, it would only affect the sub. I don't see an easy way to high pass the speakers in any case, altho some subs might be able to help in that regard if they have a high pass that would fit in with his gear. That is one of the best amps there is, and with these ratings, should be just fine for most speakers especially in a small room (and better than most avrs at lower impedance).

Continuous Average Output Power
< 0.0003 % THD+N at full rated power, 20 Hz to 20 kHz

• 100 Watts per channel into 8 Ohms, both channels driven
• 130 Watts per channel into 6 Ohms, both channels driven
• 190 Watts per channel into 4 Ohms, both channels driven
• 240 Watts per channel into 3 Ohms, both channels driven

 

[Sigberg Audio]

He could add something like a MiniDSP between the preamp and poweramp to get highpass capability.

 

[lovinthehd]

He could add something like a MiniDSP between the preamp and poweramp to get highpass capability.

I was thinking about that, but was thinking more on the easier side of things. There's also something like this https://www.hsuresearch.com/products/high-end-crossover.html but I believe OP is in UK.

 

[Andrein]

He could add something like a MiniDSP between the preamp and poweramp to get highpass capability.

I thought about minidsp too. They still have those analog 2x4hd units

 

[Andrein]

I was thinking about that, but was thinking more on the easier side of things. There's also something like this https://www.hsuresearch.com/products/high-end-crossover.html but I believe OP is in UK.

Yes, UK. But stuff comes here from US in just 3-4 days. I bought minidsp NanoAvr long time ago. Any software crossovers in JRiver or Foobar?

 

[lovinthehd]

I thought about minidsp too. They still have those analog 2x4hd units

2x4s aren't fully analog, they convert to digital for processing. I was just thinking might be a bit too involved in terms of setup.

 

[lovinthehd]

Yes, UK. But stuff comes here from US in just 3-4 days. I bought minidsp NanoAvr long time ago. Any software crossovers in JRiver or Foobar?

Then there's things like warranty, not sure Hsu even ships overseas particularly. How would you apply a software crossover, tho?

 

[Andrein]

Then there's things like warranty, not sure Hsu even ships overseas particularly. How would you apply a software crossover, tho?

Not sure. Never used either of these apps. Before sending digital signal to DAC? This setup is too expensive and unnecessary complicated for what it is

 

[lovinthehd]

Not sure. Never used either of these apps. Before sending digital signal to DAC? This setup is too expensive and unnecessary complicated for what it is

Best I can think of is if the computer indeed has analog outputs for left, right and sub, you still have the problem of volume control at the pre-amp, unless you want not to use the pre-amp and just computer sourced music. What sources does your friend use? Now, just as a friendly gesture, I'd gladly send him one of my avrs in exchange for the pre-amp/amp he's got....just to help out.

 

[Andrein]

Best I can think of is if the computer indeed has analog outputs for left, right and sub, you still have the problem of volume control at the pre-amp, unless you want not to use the pre-amp and just computer sourced music. What sources does your friend use? Now, just as a friendly gesture, I'd gladly send him one of my avrs in exchange for the pre-amp/amp he's got....just to help out.

Нe is using Tidal and a local collection of flac files. Don't think he would agree to part with his amp or preamp. He paid about £7000 for both Also I think he would like to keep his DAC. Crossovers should be done either using some device (like minidsp or another active crossover), or combination of subwoofer crossover and software on his pc. If Dirac processing can be on pc then I guess simple crossover can be too?

 

[lovinthehd]

Нe is using Tidal and a local collection of flac files. Don't think he would agree to part with his amp or preamp. He paid about £7000 for both Also I think he would like to keep his DAC. Crossovers should be done either using some device (like minidsp or another active crossover), or combination of subwoofer crossover and software on his pc. If Dirac processing can be on pc then I guess simple crossover can be too?

Yeah didn't think so, just thought I'd offer Minidsp would probably be the better route, altho some don't care for the additional processing.. Not sure what you have in mind with trying to effect a crossover in the computer, tho. 2ch Dirac is one thing, 2.1 another.

 

[Kingnoob]

Нe is using Tidal and a local collection of flac files. Don't think he would agree to part with his amp or preamp. He paid about £7000 for both Also I think he would like to keep his DAC. Crossovers should be done either using some device (like minidsp or another active crossover), or combination of subwoofer crossover and software on his pc. If Dirac processing can be on pc then I guess simple crossover can be too?

Separates are just too expensive , does it have a subwoofer output or do you gotta use line level speaker inputs ?? 8k+ for amp and preamp imagine the speakers that could buy .
With that budget I’d just get towers, and a high end sub.

 

[ski2xblack]

The miniDSP seems like it would not only be an expensive, complex solution, it could introduce a real bottleneck. The Benchmark amp would easily require more voltage than the miniDSP's max output were it in the low gain setting, and may not even get there with the amp set to high gain.

Just some thoughts from the peanut gallery.

 

[Kingnoob]

The miniDSP seems like it would not only be an expensive, complex solution, it could introduce a real bottleneck. The Benchmark amp would easily require more voltage than the miniDSP's max output were it in the low gain setting, and may not even get there with the amp set to high gain.

Just some thoughts from the peanut gallery.

What a clown show who pays $7k euros for an avr or pre amplifier without a sub output??
Op just use a subwoofer with speaker outputs on it.

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[ski2xblack]

Oh I long for the days of the red chicklets.

Hey @Andrein how OCD is the fellow you're advising? He's got options.

He may be happy just adding a sub (or two) and rolling them in where the KEFs roll off. Letting the KEFs run full range would have a bit more modulation distortion than a calibrated rig with proper bass management employed, but given the small room and expected modest spls, probably not a dealbreaker. He could plug ports of the KEFs (less phase shift with sealed alignment, easier sub blending). He could use some sort of hpf, from simple f-mods to an active crossover (e.g. miniDSP, Hsu, etc), as long as it won't hamstring all that Benchmark performance he's already purchased.

 

[Andrein]

Yeah didn't think so, just thought I'd offer Minidsp would probably be the better route, altho some don't care for the additional processing.. Not sure what you have in mind with trying to effect a crossover in the computer, tho. 2ch Dirac is one thing, 2.1 another.

Thought it is possible to apply crossover manipulations to the original signal before sending it to DAC assuming app on pc can do that?