TOPIC:

Hello,

I´m thinking of buying a DDRC-88A as a complement to my Sherbourn PT-7030 which do not have any built-in room correction system. I have a 5.4 system. I´m not sure how to best solve the timing issues between the four subs. On 3 of the subs I can adjust delays since they have their own DSP.

Could I connect only the four subs to the DDRC-88A and check the delay Dirac suggests and put them into the subs DSP and run again to check that they are aligned?

Then I connect L,C,R,SR,SL and then I have to run 3 subwoofer channels. Meaning that two subs are on 1 channel. Could this work?

Is there a better way to solve this?

Best regards
Jonas Claesson

Hi Jonas, you may find this app note helpful: minidsp.com/applications/home-theater-tu...on-with-the-ddrc-88a

I´ve read that already. But it doesn´t mention how the get the timing between the subs correct

In method A, no delay is applied to the subs. In method B, it says: "(*) The "parameters" that can be changed depend on the functionality of your subs, but the main one is the gain. You can also adjust the phase control of the sub, or the delay if you have the subs connected via an external DSP unit like the (Balanced) miniDSP 2x4."

Since they only use 1 channel for the 4 subs. delay need to be adjusted individually on the 4 subs?

Otherwise we´ll phase problem?

delay / phase control is the same thing, and it´s vital that these are correct. What I want to know if the miniDSP can tell me what delays I should put in my DSP.

If I run a calibration with 4 subs. Can I in DLCT se the result in distance or ms between the channels/subs?

@ Jontre,

If you have multiple sub, you will need to perform the tweaking/combining outside of Dirac. That's not the job of Dirac Live (single channel speaker). There is a VERY good tutorial here from AustinJerry from AVSForum (dl.dropboxusercontent.com/u/9653266/Imag...e%20March%202015.pdf)

Worth reading!

DevTeam

Here is an updated link to a revised version of the 2x4 Guide: dl.dropboxusercontent.com/u/78476446/Min...uide%20Rev%201.4.pdf

AustinJerry wrote:

Here is an updated link to a revised version of the 2x4 Guide: dl.dropboxusercontent.com/u/78476446/Min...uide%20Rev%201.4.pdf

I actually don´t need to the miniDSP 2x4 since I´ve integrated DSP on my subwoofer amp. But I´ve done the time-aligning just as you described by calculating sounds speed in air and then adjusting the delay individually on each sub.

I´ve downloaded the Dirac Live Calibration Tool and the Dirac Audio Processor Trial versions to my HTPC just to try it out before buying and DDRC-88A. But the Dirac Live Calibration Tool sets a delay of 56ms on the sub which is very wrong. Guess that's because the subs not are correctly time aligned?

BR

JONTRE

JONTRE wrote:

AustinJerry wrote:

Here is an updated link to a revised version of the 2x4 Guide: dl.dropboxusercontent.com/u/78476446/Min...uide%20Rev%201.4.pdf

I actually don´t need to the miniDSP 2x4 since I´ve integrated DSP on my subwoofer amp. But I´ve done the time-aligning just as you described by calculating sounds speed in air and then adjusting the delay individually on each sub.

I´ve downloaded the Dirac Live Calibration Tool and the Dirac Audio Processor Trial versions to my HTPC just to try it out before buying and DDRC-88A. But the Dirac Live Calibration Tool sets a delay of 56ms on the sub which is very wrong. Guess that's because the subs not are correctly time aligned?

BR

JONTRE

On what do you base your assessment that it is "very wrong"? If you are comparing the delay to the physically-measured distance, then that is not a good approach. Subs typically have an internal electronic delay that results in the Dirac-calculated delay to be different than the physical distance. I see no reason not to trust that Dirac has calculated the delay correctly.

Of more concern is whether the subs and the mains have the proper phase relationship, which can only be determined by taking measurements of the subs+mains with a tool like REW, and observing the smoothness of the splice in the crossover region. Have you done this? I can provide a link to a document that describes the process if you have not done it before.

AustinJerry wrote:

On what do you base your assessment that it is "very wrong"? If you are comparing the delay to the physically-measured distance, then that is not a good approach. Subs typically have an internal electronic delay that results in the Dirac-calculated delay to be different than the physical distance. I see no reason not to trust that Dirac has calculated the delay correctly.

The internal delay in the sub amps would in that case would only delay the subs signal. If that was the case then Dirac would have to add delay to the other speakars to align these with the sub. What Dirac does is adding more delay. It suggests a 56ms when all subs are playing. When I turn of one the subs it suggest a 10ms delay. So I suppose there is something wrong my timealign on subs?

Of more concern is whether the subs and the mains have the proper phase relationship, which can only be determined by taking measurements of the subs+mains with a tool like REW, and observing the smoothness of the splice in the crossover region. Have you done this? I can provide a link to a document that describes the process if you have not done it before.

Would love a link to that document

JONTRE wrote:

AustinJerry wrote:

On what do you base your assessment that it is "very wrong"? If you are comparing the delay to the physically-measured distance, then that is not a good approach. Subs typically have an internal electronic delay that results in the Dirac-calculated delay to be different than the physical distance. I see no reason not to trust that Dirac has calculated the delay correctly.

The internal delay in the sub amps would in that case would only delay the subs signal. If that was the case then Dirac would have to add delay to the other speakars to align these with the sub. What Dirac does is adding more delay. It suggests a 56ms when all subs are playing. When I turn of one the subs it suggest a 10ms delay. So I suppose there is something wrong my timealign on subs?

Of more concern is whether the subs and the mains have the proper phase relationship, which can only be determined by taking measurements of the subs+mains with a tool like REW, and observing the smoothness of the splice in the crossover region. Have you done this? I can provide a link to a document that describes the process if you have not done it before.

Would love a link to that document

dl.dropboxusercontent.com/u/9653266/Imag...e%20March%202015.pdf

Thank you AustinJerry.

I have actually bought a DDRC-88A now Still waiting for material to make the XLR cables though. I have an other question regarding installation of the DDRC-88A. I have an A/V-rack from Installers Choice which unfortunately is getting pretty full. I´m wondering if the DDRC-88A can be installed without having ventilation space under or above the unit?

I´m looking forward to test the unit =) Hope I won´t run in to problems with my laptop and the license since I´ve run the TRIAL of Dirac Live on it?

BR
Jontre

JONTRE wrote:

Thank you AustinJerry.

I have actually bought a DDRC-88A now Still waiting for material to make the XLR cables though. I have an other question regarding installation of the DDRC-88A. I have an A/V-rack from Installers Choice which unfortunately is getting pretty full. I´m wondering if the DDRC-88A can be installed without having ventilation space under or above the unit?

I´m looking forward to test the unit =) Hope I won´t run in to problems with my laptop and the license since I´ve run the TRIAL of Dirac Live on it?

BR
Jontre

There are no ventilation slots on the 88A case, top, bottom or sides. So I see no reason to restrict where it is placed in your equipment rack. And as long as you follow the instructions for software license registration, I don't see any reason why it shouldn't proceed successfully.

I choose to take out the HTPC from rack. That bastard was taking 4RU so now there is room for ventilation

Something I did not expect was the short USB cables, so I´ve ordered new longer cables today. I will probably get together everything except the USB cables for the calibration. I wondered briefly if I could run the filter that I did with Dirac Live Trial on my HTPC? Anyone know if this is possible?

BR //