Adding a sub to a 2ch system

[Andrein]

Buy a 2.1 preamp, the Parasound Halo P6 is excellent. This permits control of a passive subwoofer amped by any notion deemed appropriate. The PC will connect to preamp via usb for Saber DAC pleasure.

It could work but think it is in a slightly different category comparing to Benchmark products. SNR and distortion are average, not much better than avr. I think my friend wanted ultra low noise and distortion solution. I know it might be inaudible but this is what he wanted

 

[TLS Guy]

It could work but think it is in a slightly different category comparing to Benchmark products. SNR and distortion are average, not much better than avr. I think my friend wanted ultra low noise and distortion solution. I know it might be inaudible but this is what he wanted

I have come to this late. Bass management is far from essential. In fact an acoustic crossover is often by far the preferred solution. I use acoustic crossovers as much as I can. Drive his speakers full range. Set the sub crossover to the F3 of the KEF speakers plus 50%. That will probably be ideal.

 

[sterling shoote]

It could work but think it is in a slightly different category comparing to Benchmark products. SNR and distortion are average, not much better than avr. I think my friend wanted ultra low noise and distortion solution. I know it might be inaudible but this is what he wanted

The Parasound is noise free. The only thing that's distorted is your perception of meaningful sound specifications. One thing for sure is what your friend sounds like, a not too smart audio enthusiast.

 

[Andrein]

The Parasound is noise free. The only thing that's distorted is your perception of meaningful sound specifications. One thing for sure is what your friend sounds like, a not too smart audio enthusiast.

Ok. Let it be..

 

[fmw]

This is why people who buy separates should ask on these forums before hand , if you want a sub don’t buy a pre amp or intigrated amp without sub outputs /inputs.
I doubt he’d lost any sound quality with an avr or avr like preamp.
Does svs and popular brands all have high level inputs ?

Not critical. Most subs have input and output connections to put a sub in the speaker's signal path. You don't get bass management like you would with an AVR but it works just fine. I have the two channel system in my exercise room set up that way. The system is based on a small integrated amp. There are often more than one way to skin a cat.

 

[JLGF1]

eg SVS $500 sub. Problem solved.

 

[lovinthehd]

eg SVS $500 sub. Problem solved.

View attachment 61500

What model is this?

 

[JLGF1]

What model is this?

SB-2000
fixed HP xover @ 80Hz

 

[TLS Guy]

SB-2000
fixed xover @ 80Hz

Yes, it does send a fixed high passed 12 db per octave signal back to the power amp.

 

[Kingnoob]

eg SVS $500 sub. Problem solved.

View attachment 61500

I didn’t see any speaker inputs , how is this going to work without a subwoofer output on the ops integrated amp?

 

[isolar8001]

I didn’t see any speaker inputs , how is this going to work without a subwoofer output on the ops integrated amp?

Works quite easily....
Preamp out to sb-2000 input.
sb-2000 output to integrated amp. electronic crossover achieved...easy peasy.
This thread could have stopped at 3 replies if the sb-2000 was suggested then.

Otherwise TLS Guys suggestion of an acoustic crossover is the best suggestion....tried and true and easy works just fine.

 

[TLS Guy]

I didn’t see any speaker inputs , how is this going to work without a subwoofer output on the ops integrated amp?

You send the pre amp outputs to the sub line inputs, and connect the sub line outs to the power amp inputs. Strangely this sub has limited bass management with an 80 Hz crossover frequency only.

The OP does not have an integrated amp, but separate pre-amp and power amp. That is the best way to do it, with voltage gain and controls separated from the power amp section.

 

[Kingnoob]

You send the pre amp outputs to the sub line inputs, and connect the sub line outs to the power amp inputs. Strangely this sub has limited bass management with an 80 Hz crossover frequency only.

The OP does not have an integrated amp, but separate pre-amp and power amp. That is the best way to do it, with voltage gain and controls separated from the power amp section.

Wow sounds confusing but glad a solution is found for the op when he returns .

Works quite easily....
Preamp out to sb-2000 input.
sb-2000 output to integrated amp. electronic crossover achieved...easy peasy.
This thread could have stopped at 3 replies if the sb-2000 was suggested then.

Otherwise TLS Guys suggestion of an acoustic crossover is the best suggestion....tried and true and easy works just fine.

ahh I see , preamps would be better to just have a sub output like an avr . I’d need a picture to understand this lol glad I don’t got any equipment like this .

 

[isolar8001]

Wow sounds confusing but glad a solution is found for the op when he returns .

ahh I see , preamps would be better to just have a sub output like an avr . I’d need a picture to understand this lol glad I don’t got any equipment like this .

All a sub output is is a mono preamp output that usually has an electronic crossover point applied. (usually adjustable)
In the case of using the Sb-2000, there is an electronic crossover built in with a high pass output...a basic non controllable one, but good enough.
So in this use case, a full range signal will be sent from his preamp and the sub will deal with the crossover points.
The sub will do 80hz and down and 80hz and up will be sent to his main amp.

 

[lovinthehd]

All a sub output is is a mono preamp output that usually has an electronic crossover point applied. (usually adjustable)
In the case of using the Sb-2000, there is an electronic crossover built in with a high pass output...a basic non controllable one, but good enough.
So in this use case, a full range signal will be sent from his preamp and the sub will deal with the crossover points.
The sub will do 80hz and down and 80hz and up will be sent to his main amp.

But keep in mind it's just a crossover of slopes, 80hz is just that place in the middle so to speak.

 

[JLGF1]

I didn’t see any speaker inputs , how is this going to work without a subwoofer output on the ops integrated amp?

Line-level, not speaker-level. Did you notice what I circled?

(a) OP doesn't have an integrated amp. He has separate pre-amp/power amp.
(b) he HAS a line-level sub out, but won't actually need it in this scenario because it has no bass management. Line-level L/R is routed to sub. Sub handles below 80Hz. Above 80Hz is sent on to the mains.(roughly, it's sloped not brick wall)

 

[TLS Guy]

But keep in mind it's just a crossover of slopes, 80hz is just that place in the middle so to speak.

The crossover slopes are not specified. The slopes of bass management in receivers and AVPs, is second order high pass (12db) per octave and fourth order low pass (24db) per octave.

This was chosen by THX at the start of HT. They actually specified that the bed speakers be sealed. They roll of second order. So this made the crossover symmetrical as you then have 24db per octave high and low slopes.

What happened in reality is that speakers are in the main ported, with a 24db per octave roll off at F3. So then you end up with sixth order high pass and forth order low pass. It gets worse then that as if you cross at 80 Hz and the mains have an f3 of say 50 Hz then you have high pass second order transitioning to sixth order at 50 Hz. So we actually have a real mess.

That is why for ported speakers, if they are capable, I strongly advise LFE + main setting the crossover a little above f3 of the mains, and certainly no higher then f3 plus 50%. Then you are likely to end up with a symmetrical fourth order crossover.

Really speakers do need to be designed as an integrated system ideally and that is the approach I take.

 

[PENG]

Keep in mind the OP said his friend wanted ultra low noise/distortions, presumably comparable to that of the AHB2. So, any SVS or similar subs with high pass speaker level or line level output kind of solutions are not likely going to be acceptable to him.

 

[PENG]

Yes, once my friend is back from holiday, we'll look at all these options. It will also depend if he can and want to replace his Benchmarks with something else, e.g. Minidsp SHD + Hypex NC502. Even if he is concerned about very low distortion this combination would work very well. And is cheaper. But that would not be all separates route. Let's see. There are not many options, but we can try at least. I think he tried to run some sub with speakers running full range and did not like results. But then I need to check how he actually connected that sub.

The minidsp SHD has high enough output for the AHB2 so he doesn't need to replace it with a Hypex amp unless he wants to.

 

[everettT]

Keep in mind the OP said his friend wanted ultra low noise/distortions, presumably comparable to that of the AHB2. So, any SVS or similar subs with high pass speaker level or line level output kind of solutions are not likely going to be acceptable to him.

Is it confirmed yet that Benchmark will be the preamp, I just couldn't go back and read after what I last remembered?

Edit: I see the MiniSHD is in the chain.