Preamp with bass management?

[pearsall001]

And no, I'm not looking to buy a new preamp! There, that's out of the way. I'm just curious about how one would incorporate one into a system with an AVR & subs. The AVR has bass management that's used for both HT & 2 channel. The separate preamp would be used with HT bypass for movies & then the AVR would be shut off for 2 channel.

How would you get the subs bass management incorporated using the pre? I know Parasound and other companies make 2 channel pre's with built in bass management. But if the pre doesn't have the bass management...how's the hookup go?

[phipiper10]

I'm out of my league here but wouldn't you run L/R speaker wire from the same out on the pre as is used by the L/R speakers to the Sub and set the subs crossovers?

Ducking for cover now....who has the right answer?

[adam2434]

If the preamp has bass full management (sets a high pass for the speakers and low pass for the sub), perhaps you could set the L/R to "large" in the AVR, set sub to "no". This should direct the LFE channel to the L/R preouts.

Then, you would connect the AVR's L/R preouts to a standard input on the pre and calibrate levels using the specific volume level on the pre. You would have to set to this same volume level every time you use the AVR.

I don't think you'd be able to use a pre's HT Bypass because I don't think you would get the pre's bass management in this mode.

Hmmm, with a pre without bass management, I think you would want a crossover between the pre and amp to set a high pass filter for the L/R and low pass filter for the sub. Something like this: http://www.hsuresearch.com/products/high-end-crossover.html

In a non-HT situation, if the pre had 2 sets of outs, you could connect one set to your amp and one set to the sub. Then use the sub's low pass filter to blend with the main speakers. This isn't bass true management though, as the mains would not be filtered. I would not recommend this approach for HT, as your mains would get the LFE channel if you had things set up as in the first 2 paragraphs.

[Kex]

This will probably seem like a stupid question, since I'm not quite sure what you are attempting exactly, but, what are you hoping for that you would not achieve by simply using seperate memorized settings on the AVR:

- 1 setting for HT, with speaker sizes, how many speakers to use, bass settings etc.
- 1 setting for 2ch, with speaker sizes, main speakers only, bass settings etc.

Or are you hoping to be able to turn off the T765, and bypass it completely for two channel listening, using a pre and a seperate amplifier? I'm confused ...

[adam2434]

Another thought...

Some subs have line level ins and outs with a high pass filter on the outs. I had a Velo a few years back with this feature. It had a selectable 80 or 100Hz high pass filter on the outputs. This was a nice feature for integrating a sub into a 2-ch system.

In this case, you would do the same as is in the 1st 2 paragraphs above. Then, you would run interconnects from your pre to the subs inputs and run interconnects from the sub's outputs to your amp. Lastly, you would set the sub's low pass filter for optimal blend with the high pass filter applied to the L/R speakers.

[adam2434]

Yes, I believe he looking for ways to integrate a preamp for 2-ch with a sub, but also use the sub for HT with an AVR.

[adam2434]

In a quick look, your subs have the line level ins and outs with the high pass filter (80Hz) on the outs, so what I described above would work.

Kudos to Velo for keeping that feature.

[pearsall001]

Yes, I believe he looking for ways to integrate a preamp for 2-ch with a sub, but also use the sub for HT with an AVR.

That's it exactly. The pre would be in HT bypass mode for movies utilizing the AVR's bass management. For 2 channel the AVR is turned off. Now how do you get to use the same dual subs with the pre for 2 channel? The AVR is completely out of the picture at this point. This shit is confusing as hell!!! :confused:

[adam2434]

That's it exactly. The pre would be in HT bypass mode for movies utilizing the AVR's bass management. For 2 channel the AVR is turned off. Now how do you get to use the same dual subs with the pre for 2 channel? The AVR is completely out of the picture at this point. This shit is confusing as hell!!! :confused:

I've never seen a pre that has a HT bypass for L/R and sub - maybe it exists, but never seen one.

So, assuming the pre does not have a bypass for sub, you will not be able to have the sub only connected directly to the AVR and still use the sub with the pre when the AVR is off. The sub would have no way of getting a signal from the pre.

The steps I provided earlier should allow the sub(s) to work for HT and 2-ch with a pre.

I'll try to paraphrase:

1) In AVR, set L/R to "large" and "no" sub. This will provide the LFE and bass from channels set to "small" to go out the AVR's L/R preouts. I believe this should work, but you would have to verify that the LFE is being redirected properly to L/R preouts. The goal here is to get the bass into the L/R channel so that the sub won’t need to be connected to the AVR at all.

2) The AVR’s L/R preouts get connected to a standard input on the pre.

3) Since the pre’s volume control is active, you will have to calibrate the pre’s volume with the rest of the channels form the AVR. The pre’s volume would need to be set to this volume every time you use the AVR.

4) Implement bass management in the 2-ch signal with one of these 3 options
a) in the pre (if it has it)
b) or using the sub’s line level ins/outs (in your case, one sub would get the R preamp signal and the other would get the L)
c) or using an external crossover.

For b) and c), you would effectively have a filter/crossover between the preamp and amp, to provide a high pass filter for the L/R speakers and low pass filter for the sub.

5) For 2-ch with the pre, the AVR would not need to be on at all. However, you would need to have 2-ch sources connected to other inputs on the pre. You would select one of these sources and adjust the pre’s volume as normal. The sub’s volume will scale with the pre’s volume. The only thing you may need to tweak is the sub’s level a bit, as you might like to run the sub a little hotter for HT vs. 2-ch music.

This is all a bit unconventional, but I think the above could work. This approach really puts the priority on integrating the sub for 2-ch, so the compromises are more on the HT side.

[Kex]

Are you still using the AVR amplification in two channel mode? This is the part I don't understand in your scenario.

If not, I am guessing you can just use splitters on the subwoofer input to have two inputs to the same line in: one input from the AVR for HT, one input from the pre for two channel. So the AVR would be in charge of everything for HT, but could still be off when listening to two channel with the pre and an external amplifier. As stated previously, I'm just guessing ...

[Early B.]

That's it exactly. The pre would be in HT bypass mode for movies utilizing the AVR's bass management. For 2 channel the AVR is turned off. Now how do you get to use the same dual subs with the pre for 2 channel? The AVR is completely out of the picture at this point. This shit is confusing as hell!!! :confused:

Not confusing at all. At one point, I had my system set up like this using dual subs. Since the subs were hooked up to the preamp, I could use them for both systems without a problem. You'll need two pair of preouts on the preamp.

If you're still confused, PM me with your phone number and I'll explain it. It's easy to do.

[jm1]

If I recall correctly, you have a SMS-1.

The pre would go to the SMS-1 which would go to the Nikko amp. The SMS-1 would connect to both subs using only one of the subs L+R inputs.

The LFE out from the AVR would be split to go to both subs. You would use the other channel of the L+R input not used by the SMS-1. Make sure you disable the active crossover in the sub.

The L+R of the AVR would go to the pre HT bypass. The AVR L+R would be set to FULL or LARGE or what ever it is called.

You now have a hierarchy of optimizating the subs. You would need to experiment which Velo room correction should be run first or if you need both.