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Discussion Starter #1
So I’ve gotten a few ppl ask about putting a ddrc22d or ddrc24 upstream of of there dsp and what’s the difference rather than buying a 8x12DL C-DSP so here you go


Will it work ? Yes! Absolutely will in every way. However the CDSP offers it all in one with a higher voltage output and has multiple Dirac channels and has bass management and has it all in one package. So we’re not going D/A back to A/D than back to D/A . That by itself is worth considering just buying the 8x12DL.
The completion of the Dirac integration in the 8x12DL is much preferable except in one instance. And that is using a ddrc22d upstream. Than it’s the same thing. Except the ddrc22d cuts an added 6db of signal vs the ddrc24 or cdsp


Starting with the ddrc22d

It runs at 96k so there’s 3072 fir taps per channel where the 48k in the ddrc24 and cdsp get 8192 taps per channel at 48k

The ddrc22d with 3072 taps still will do a complete correction and works to my ears just as good. But there’s the numbers that I know of from looking at data sheets on both and simply dividing and multiplying the offsets by 2 (48x2,96)
As the data sheet actually doesn’t say the actual fir power so I have the reference the 2x4hd datasheet and opendrc datasheet which are respectively the same exact sharc boards.


So using a ddrc22d upstream on a digital connection into your dsp will do the Dirac calibration in every way as good as the Cdsp Dirac calibration in 2ch mode.
The ddrc22d takes 5v input and is very easily converted using a 12v to 5v converter (a usb to cigarette lighter adaptor works fine) you have to cut a usb cord and find the wires that read 5v with the correct polarity with a DMM and splice that to the power jack connector. Easy peasy 5min cheesy conversion that works great. If your a sticker about the power on the I2s being ripple free (the master clock etc etc ) use a minidc isolator on the 12v side of the conversion cable that you make. Using a minidc will not only isolate the power (no noise) it will also give you a remote turn on ability. So order a minidc when you plan on using either the ddrc22d/24 models.

If you don’t order a minidc and just power it off the usb adaptation you can use a SPDT/SPST Bosch type delay and do a remote boost to a higher power source (remote turn on to a 5A or more service as your radio remote can only output 500ma or so.

If converting the ddrc24 there is no need for a usb adaptation as the ddrc24 runs at 12v. You can put regular car power direct into it but it will have noise . So order the minidc and effectively convert it to car.

The nice thing about the minidc from minidsp it is designed to convert the ddrc24 to car audio. So it’s a perfect match. Done and done


So the ddrc22d upstream would work great with any dsp. It would tune exactly the same a 8x12DL in two channel Dirac mode so all timings and pre tune would apply the exact same.

The ddrc24 has analog output. So you’ll have 4ch output , but could only use two channels output of the ddrc24 into your dsp

Or just use the ddrc24 as your main dsp if you are running passive crossovers and or crossovers built in amps.


The end result as far as the Dirac calibration goes is the exact same as the Cdsp except in the ddrc24/ddrc22d runs the new Dirac 2.0 version.


The price of the ddrc22d is near the same as the 8x12DL so might as well but the 8x12DL and get more as it’s packed with other things besides Dirac and is a excellent dsp as well.

A ddrc24 upstream of a dsp would surly get Dirac calibration on the cheaper side but your sacrifice analog to digital conversion that isn’t preferred but works nevertheless.


In my car I use a ddrc24 on 2 pair speakers stand alone
Than .

A ddrc22d going out to two 2x4hds as fir crossovers and DAC for another two pair speakers for a total of 5 sharc boards on a 4way system. It’s extremely complicated I have to align the impulse of each channel to the longest delayed dsp and have 4 dsps to jump around when ever I make changes It’s extremely complicated but works superb. I color coded all my 4 usb cords that go to each processor and have unlimited control over everything with two separate Dirac machines for over 18,000 fir taps. This is not for the faint hearted user but definitely gets it done. When I run just the 8x12DL and nothing else it’s barely a difference. The 8x12DL is that good. If it’s within your budget that is the one to get. No doubt about it. If you just want Dirac on the cheap the ddrc24 will do the trick and get you a good sounding calibration. The ddrc22d would be better as it’s digital but requires a digital source.

Hope that answers some of the questions about using other Dirac machines in conjunction with your dsp. However you implement Dirac it will still kick the *** out of what you can do on your own.

Best of luck .
 

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Thanks Oabeieo as I’ve still been wondering what you mean by multiple Sharcs and what that gains you. I thought you were running multiple DDRC units in series, which made me wonder about DA/AD conversions. Now with 2x4HDs in there, I’m really not sure what those extra Sharch boards offer since they don’t run Dirac. I guess you’re using those for extra manual processing. It’s your thread and maybe you don’t want to go into it but I don’t really understand the benefit of the extra Sharc/2x4HDs.

But thanks for sharing the DDRC options as that could definitely be useful for some though I agree the MiniDSP 8x12DL should be better...once they implement Dirac 2.0.
 

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Discussion Starter #4
Thanks Oabeieo as I’ve still been wondering what you mean by multiple Sharcs and what that gains you. I thought you were running multiple DDRC units in series, which made me wonder about DA/AD conversions. Now with 2x4HDs in there, I’m really not sure what those extra Sharch boards offer since they don’t run Dirac. I guess you’re using those for extra manual processing. It’s your thread and maybe you don’t want to go into it but I don’t really understand the benefit of the extra Sharc/2x4HDs.

But thanks for sharing the DDRC options as that could definitely be useful for some though I agree the MiniDSP 8x12DL should be better...once they implement Dirac 2.0.
Well the 8x12DL 1st off is pretty dam good , adding 2.0 isn’t going to be a world of difference. The changes in 2.0 are barely noticeable. And I mean barely.
The 8x12DL is by far the best dsp our right now as far as why kind of sound quality the average user can attain per hour behind the screen

A sharc is a chip. It does the dsp work. Each sharc is capable of a finite amount of processing.
 

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A sharc is a chip. It does the dsp work. Each sharc is capable of a finite amount of processing.
Right, I understand that but I assumed (maybe incorrectly) that most of the processing was done by Dirac aligning the output to target curve via minimum phase. So what additional (manual?) FIR processing are you doing with the additional Sharcs? That’s where I’m a little lost on what you’re doing and the benefit.
 

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Discussion Starter #6 (Edited)
Right, I understand that but I assumed (maybe incorrectly) that most of the processing was done by Dirac aligning the output to target curve via minimum phase. So what additional (manual?) FIR processing are you doing with the additional Sharcs? That’s where I’m a little lost on what you’re doing and the benefit.

Dirac is the software the sharc is the hardware. The sharc is in almost every newer minidsp , a few other dsps use sharc as well . It was designed I believe as a graphics card chip but adopted to dsp as it’s language is compatible easily



I am using linear phase crossovers that requires fir processing on everything except my high frequency drivers , those just run through a Dirac ddrc24 that is a Dirac/dsp/DAC for high frequency

My low frequency drivers go though a ddrc22d than to 2x4hds

The ddrc is Dirac digital in and out to the HD’s for low frequency
The 2x4hds are linear phase crossovers/dsp/DAC for low frequency


2 seperate Dirac machines one for HF and one for LF


I don’t necessarily need linear phase crossovers for HF as that Dirac machine can smooth the phase twist on the sum , those speakers are mounted next to each other so the sum and Tim and acoustic center is equal so the sum of the phase is very close on the LP and HP so what Dirac does to smooth the sum is dam near linearization

The LF side just needs linearization pre Dirac to be to my liking.
There is no crossover interference. It’s literally non existent in my car.
I can shape my stage any way I want without any wierd time domain issues caused by crossovers.

Them the LF Dirac solves the room issues and does eq work very nicely .


I simply use delay to line up the LF side to the HF side.
The LF side is linear phase so not only is it a slam dunk to do it by ear but also extremely easy to line up the impulses. I’m easily within 1 sample alignment.
 

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So one could use the ddrc22 before a Helix that already has the crossovers set up and close to where it needs to be?
 

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Discussion Starter #8
So one could use the ddrc22 before a Helix that already has the crossovers set up and close to where it needs to be?

Absolutely. And it would work amazing


Simply do tape measure distance on your TA setting andplay with your left and right levels to promote a 2ch eq and you should be good to go.

I did it that way for a long time. It works great.


So for you guys that are still in the romance stage with the helix the ddrc22d would be stellar .

For the same cost could just go with the Cdsp and get it all in one package plus 7more Dirac channels of you have rears or center
 

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So one could use the ddrc22 before a Helix that already has the crossovers set up and close to where it needs to be?

Absolutely. And it would work amazing


Simply do tape measure distance on your TA setting andplay with your left and right levels to promote a 2ch eq and you should be good to go.

I did it that way for a long time. It works great.


So for you guys that are still in the romance stage with the helix the ddrc22d would be stellar .

For the same cost could just go with the Cdsp and get it all in one package plus 7more Dirac channels of you have rears or center
That's pretty cool. I'm still not ready to give up on the tune it yourself just yet. But that is a cheap way to give it a shot and I could always use that in my home system.
 

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So one could use the ddrc22 before a Helix that already has the crossovers set up and close to where it needs to be?
It works very well. Using the DDRC22D into digital coax of my DSP Pro mk2.

The DDRC 22D will perform a stereo R and L Dirac calibration on the entire matrix of the Helix DSP. So all the right divers are treated as a single loudspeaker and all the left drivers are treated as as a single loudspeaker. You can include stereo subwoofer or mono sum subwoofer. If you want to go further and have more FIR filters for possible individual driver XO or more EQ, then you can place a DDRC24 or 2x4HD unit downstream the RCA outputs of your DSP.

*This can be done in the “auto FIR” format = Dirac Live (using Dirac Live calibration tool)
*This can be done in the “manual FIR” = OpenDRC and 2x4HD units (using rePhase)

Tuning Process​

MEASURE EACH DRIVER TO ESTABLISH PROPER XO(on Helix or other DSP)

TIME ALIGN EACH DRIVER USING MEASURING TAPE(on Helix or other DSP)

*optional*USE NULLING TECHNIQUE (Drop1’s METHOD)(on Helix or Other DSP)
I recently started doing this to fine tune T/A or phase. I perform it within each like pair of drivers first, then perform it again with like pairs against other like pairs. I use the front mid-bass drivers as the anchor for the system. I inverse polarity on the midranges and alter delay (been playing around with the method by either altering T/A or altering phase) until tones are most out of phase then flip midranges polarity back to normal. Next is to proceed to do the same thing except this time with midranges anchoring against the tweeters. I invert polarity on the tweeters and alter delay until tones are most out of phase then flip tweeters polarity back to normal. Lastly perform this step again with midbass as the anchor against rear fill drivers and subwoofers.

EQ WITH DIRAC LIVE
  • Perform DIRAC LIVE Calibration or place FIR filters on any downstream unit. I personally use a DDRC24 to calibrate the REAR channels to the driver's seat. This calibrates the rear channel drivers to deliver the best stage and they can to the driver listening position. This is performed with woofers playing R and L signal (not differential L-R signal which defeated until all tuning is done).
  • Perform DIRAC LIVE Calibration or place FIR filters on any upstream unit. I personally use a DDRC22D to calibrate the car’s LEFT and RIGHT channels. This also incorporates my SUBWOOFER (mono sum) and my already DIRAC LIVE calibrated REAR channels. This is a “MASTER” EQ and will perform DIRAC Live with the entire LEFT (both FRONT, REAR,& SUB) as 1 LEFT loudspeaker while the entire RIGHT (both FRONT, REAR, & SUB) as 1 RIGHT loudspeaker.
*Been using Dirac 2.0 on both units. “Couch (focused)” and “Chair” algorithms seem to be working best so far.

DDRC24 POWER: I did not have success powering the DDRC24 with 2 different miniDSP DC isolators purchased from miniDSP. It simply did not power the unit. I use a Mean Well isolated DC/DC SD-15A-12 converter purchased from Mouser to provide noise free power to the DDRC24
 

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I'm confused on the ddrc 24. You say you can't use 2 of the 4 channels to the dsp. So it will only do front left and right. No sub.
 

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As Oabeieo previously mentioned:
A ddrc24 upstream of a dsp would surly get Dirac calibration on the cheaper side but your sacrifice analog to digital conversion that isn’t preferred but works nevertheless.
I'm confused on the ddrc 24. You say you can't use 2 of the 4 channels to the dsp. So it will only do front left and right. No sub.
When using a DDRC24 OR DDRC22D upstream of a DSP:

If you have stereo subs and enable them to play on your DSP before the Dirac Live is performed, then the left sub will be included in the L channel calibration and the right sub will be included in the right channel calibration.

If you have mono sum subwoofer and enable it to play on your DSP before the Dirac Live is performed the subwoofer will play during the L channel calibration and the subwoofer will also play during the right channel calibration.

Both methods will include the subwoofer into your House Curve that can be easily shaped with Dirac Live.
 

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I'm confused on the ddrc 24. You say you can't use 2 of the 4 channels to the dsp. So it will only do front left and right. No sub.
If you have stereo subs and enable them to be on on your DSP before the Dirac Live is performed, then the left sub will be included in the L channel calibration and the right sub will be included in the right channel calibration.

If you have mono sum subwoofer and enable it to be on on your DSP before the Dirac Live is performed the subwoofer will play during the L channel calibration and the subwoofer will also play during the right channel calibration.

Both methods will include the subwoofer into your House Curve that is shape be with Dirac Live.
Thanks for clarifying. Guess that's how I'm gonna do it. I ordered one. Impulse buy. Hopefully I can get it right. I've been having a hard time getting my sub to sound right with all music. It sounds up front with most stuff but some stuff sounds off. Which it probably is.
 

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Thanks Oabeieo, that post cleared up my confusion, you’re using the additional processing power to do linear phase crossovers and a little delay. Cool idea though as you stated, a lot more complexity. But you’ve got the equipment and obviously have the skills so why the hell not. The last few percent of audio improvement are usually quite a bit more expensive or take a lot more work. Thanks for sharing your magic. :)

EDIT - Just thinking, could you take a measurement of the same target curve using the simple setup with the 8x12DL and your complex multi-Sharc configuration? Would be interesting to see which graphs show a difference such as impulse response. Would be interesting if we could see in graphs, the smooth/sweetness you’re hearing. May not show but would be interesting to check.
 

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How long after purchasing can I download the Dirac stuff. It let me download the config tool but not the rest. I'm hoping to learn it a little before I get it.
 

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Has anybody ever heard of using 2 outputs with the same signal and reversing the polarity to double the output voltage of a dsp? Just like bridging an amp. Since 2 of the 4 outputs will be unused on the ddrc 24 I bought I was thinking I could double my voltage that way. Am I onto something or am I nuts?
 

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Has anybody ever heard of using 2 outputs with the same signal and reversing the polarity to double the output voltage of a dsp? Just like bridging an amp. Since 2 of the 4 outputs will be unused on the ddrc 24 I bought I was thinking I could double my voltage that way. Am I onto something or am I nuts?
Why would you reverse the polarity of one channel? Yes you are nuts but you arent the first to think of it

Just last week I was contemplating the same.
Since my amp takes 2 inputs to bridge (duh) I considered using 2 channels of dsp for each mid.
No doubt it would work but why? Amps have a low/high input and my helix can already put out an 8v signal.
It was neat to think about but I couldnt see any real value. The amp will only make as much power as it will make no matter how much voltage you force feed it.
 

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Right, I understand that but I assumed (maybe incorrectly) that most of the processing was done by Dirac aligning the output to target curve via minimum phase. So what additional (manual?) FIR processing are you doing with the additional Sharcs? That’s where I’m a little lost on what you’re doing and the benefit.
FYI Dirac Live uses mix-phase correction.
 
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