mono rear fill speakers?

[olds1959special]

If I sum the L/R and flip the polarity then send to the rear speakers, will I be emulating an old-school rear fill speaker?

I'm trying to emulate something along the lines of a Hafler circuit using active speakers but I can't seem to figure out an easy way to do it, so I'm looking for something else I can try.

 

[NTK]

If you want to try the Hafler circuit, use the decoding matrix in Wikipedia. You should be able to easily implement it using your miniDSP 2x4 HD.

Matrix decoder - Wikipedia

en.wikipedia.org

 

[olds1959special]

If you want to try the Hafler circuit, use the decoding matrix in Wikipedia. You should be able to easily implement it using your miniDSP 2x4 HD.

Matrix decoder - Wikipedia

en.wikipedia.org

How would I do this with the MiniDSP 2x4 HD? That is in my other system anyway. Can I do it without the MiniDSP?

 

[NTK]

How would I do this with the MiniDSP 2x4 HD? That is in my other system anyway. Can I do it without the MiniDSP?

With miniDSP, you can do it using signal routing.

Signal routing - miniDSP 2x4 HD User Manual

docs.minidsp.com

Easier with miniDSP. And the miniDSP will still be useful when you get bored of the Hafler thing.

 

[janbth]

With miniDSP, you can do it using signal routing.

Signal routing - miniDSP 2x4 HD User Manual

docs.minidsp.com

Easier with miniDSP. And the miniDSP will still be useful when you get bored of the Hafler thing.

I don’t think you can invert the signals you are mixing with the 2x4 HD. You would need a FLEX HT/HTx for that. Or am I missing something?

 

[NTK]

I don’t think you can invert the signals you are mixing with the 2x4 HD. You would need a FLEX HT/HTx for that. Or am I missing something?

Yes, however, for that miniDSP has created special plugins.

 

[olds1959special]

I was able to sum the L/R of the rear speakers by using a multi-output device and using the mono button on my Apogee Duet software.

Is it true that if the rear speakers are phase inverted and summed, this will be the same as a rear fill channel?

 

[Wayne Highwood]

Is it true that if the rear speakers are phase inverted and summed, this will be the same as a rear fill channel?

No. Well, it would be a fill channel, but it won't be a Hafler rear channel, or a Dolby pro logic style rear channel.

Why not leave the historical technocuriosities to the past, and use an AVP/AVR, or the miniDSP for this? Using active monitors limits you to doing this matrixing at line level, which means a mixer of some sort for the two channel material. Modern kit can do all this, and discreet multichannel, and brings more effective bass management, and...

 

[janbth]

Yes, however, for that miniDSP has created special plugins.
View attachment 484834

Sounds good - I didn't know such a thing existed! I can't find the download, though. Are you sure this plugin applies also to the 2x4 HD, and not just the 2x4?

 

[NTK]

Sorry. I have no idea. How difficult can it be for miniDSP to implement channels differences ( A - B = A + (-B) ) when channels summing is there?

 

[olds1959special]

No. Well, it would be a fill channel, but it won't be a Hafler rear channel, or a Dolby pro logic style rear channel.

Why not leave the historical technocuriosities to the past, and use an AVP/AVR, or the miniDSP for this? Using active monitors limits you to doing this matrixing at line level, which means a mixer of some sort for the two channel material. Modern kit can do all this, and discreet multichannel, and brings more effective bass management, and...

I am experimenting with what I have now. I think I'm getting pretty good results this way I think, but wanted to check if this sounds like an okay method:

I use a SMSL DO100 Pro DAC / Topping A70 Pro pre-amp to feed the main front speakers.

I combine this DAC with an Apogee Duet 3 DAC as a multi-output device.

I choose the SMSL DO100 Pro as the main source and select drift correction on the Apogee Duet 3.

There is a slight delay from processing but this way it ends up on the rear speakers.

I run cables with in-line phase reverse barrels going to the rear speakers.

I turn down the high trim and low trim on the rear speakers to emulate a high and low pass filter.

I sum the rear speakers to mono using the Apogee software and turn them down by 10dB relative to the mains.

 

[JustJones]

Sounds good - I didn't know such a thing existed! I can't find the download, though. Are you sure this plugin applies also to the 2x4 HD, and not just the 2x4?

Depends on how old the 2x4 HD is. If it still runs on the old plug-in model you need to migrate to device console. I'm not sure you can still get the plug-ins the datasheets are located in downloads.

The miniDSP Device Console​

The miniDSP Device Console ("DC") is the new configuration and control software for miniDSP audio processors. It replaces the earlier "plugin" control software. In contrast to the earlier software, Device Console provides:

• A single software program to control all miniDSP processors

 

[Wayne Highwood]

I am experimenting with what I have now. I think I'm getting pretty good results this way I think, but wanted to check if this sounds like an okay method:

Yeah, that will give you a summed, out of phase, -10db attenuated rear channel. Is that an ok method? That's your call. What It won't give you is rear channels derived from a difference signal (which is the secret sauce of both the Hafler and Dolby PL methods).

 

[janbth]

Depends on how old the 2x4 HD is. If it still runs on the old plug-in model you need to migrate to device console. I'm not sure you can still get the plug-ins the datasheets are located in downloads.

I have the new Device Console on my 2x4 HD, which is 2-3 years old. I have looked all over the miniDSP webpage and in my downloads page, but I can’t find any plugins. There’s unfortunately no option to invert incoming signals in the mixing matrix in the Device Console.

 

[NTK]

I think this kludge may work to implement the Hafler circuit:

• Invert polarity of one of the two input channels, for example, L.
• Use an input biquad for the polarity inversion. However, we'll need to enter the biquad coefficients manually in the advanced mode.
  See: https://www.minidsp.com/community/threads/invert-inputs-on-c-dsp.12494/
• To get the correct L channel output, we'll with need to reverse its polarity again at the L channel output
• Nothing special is needed for the R channel.
• For the L rear, we need L - R = -( -L + R ), which mean add the inverted L and the R, reverse polarity at the output.
• For the R rear, we need R - L = -L + R, which mean add the inverted L and the R and output directly

 

[JustJones]

I have the new Device Console on my 2x4 HD, which is 2-3 years old. I have looked all over the miniDSP webpage and in my downloads page, but I can’t find any plugins. There’s unfortunately no option to invert incoming signals in the mixing matrix in the Device Console.

The plugin doesn't work on the 2 x4 HD and it costs $10 if you have the older 2x4.

Rear/Center Channel

Rear/Center Channel

www.minidsp.com

 

[olds1959special]

I think this kludge may work to implement the Hafler circuit:

• Invert polarity of one of the two input channels, for example, L.
• Use an input biquad for the polarity inversion. However, we'll need to enter the biquad coefficients manually in the advanced mode.
  See: https://www.minidsp.com/community/threads/invert-inputs-on-c-dsp.12494/
• To get the correct L channel output, we'll with need to reverse its polarity again at the L channel output
• Nothing special is needed for the R channel.
• For the L rear, we need L - R = -( -L + R ), which mean add the inverted L and the R, reverse polarity at the output.
• For the R rear, we need R - L = -L + R, which mean add the inverted L and the R and output directly

does this look right?

 

[janbth]

does this look right?View attachment 484990
View attachment 484988

Output 3 and 4 should have both Input 1 and 2 selected, but everything else looks right to me.

 

[olds1959special]

Output 3 and 4 should have both Input 1 and 2 selected, but everything else looks right to me.

It sounds like it's working now. Thank you!

 

[olds1959special]

No. Well, it would be a fill channel, but it won't be a Hafler rear channel, or a Dolby pro logic style rear channel.

Why not leave the historical technocuriosities to the past, and use an AVP/AVR, or the miniDSP for this? Using active monitors limits you to doing this matrixing at line level, which means a mixer of some sort for the two channel material. Modern kit can do all this, and discreet multichannel, and brings more effective bass management, and...

It's working now with the MiniDSP, is there anything else I should know? Do I need to add a delay to the rears? As it is they are a bit further away than the front pair, so there's a natural delay. Should the rear speakers be calibrated to be lower in volume by 3-6dB?