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Side note. I've had good success with not being in the car for the first center measurement. Seems to give me a better center. Just taped my mic to the headrest.



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I need to sum all 8 of my factory high-level inputs to get a full signal for teh 8x12DL. Any ideas how I can make that happen? I'm really interested in picking one of these up to play with, currently using the Helix Pro MK2.
 

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Use your Helix to sum the hi level then output the summed signal to channel AB as full range which then goes to the Minidsp.

But really what car do you have that requires 8 channel of summing? You really only need the front speakers and the sub signal.


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Jaguar XF with the Meridian system. The factory system has x-overs applied to the tweeters, midrange, midbass, and sub.

I had thought about just using the Helix as you suggested, but man that makes it one expensive line out converter. I was hoping that selling it could defray some of the 8x12 cost.
 

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Jaguar XF with the Meridian system. The factory system has x-overs applied to the tweeters, midrange, midbass, and sub.



I had thought about just using the Helix as you suggested, but man that makes it one expensive line out converter. I was hoping that selling it could defray some of the 8x12 cost.

Isn't that system 5.1/7.1? Unless you have the option to play standard stereo, it's not gonna work so well with the CDSP. You might want to create a new thread asking.

My opinion about summing is that it's crap. You're losing out so much because that signal is so colored by mediocre processing that by the time the CDSP gets its hands on it, it's turd.

A clean source and hi-res content is top of the priority list in my system.


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Isn't that system 5.1/7.1? Unless you have the option to play standard stereo, it's not gonna work so well with the CDSP. You might want to create a new thread asking.

My opinion about summing is that it's crap. You're losing out so much because that signal is so colored by mediocre processing that by the time the CDSP gets its hands on it, it's turd.

A clean source and hi-res content is top of the priority list in my system.


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I have the "base" Meridian. The step up is the one with the center channel. Yeah, I didn't like how the factory amp in my old car summed and ended up just using a HEC card in the Helix and bypassing everything. Might have to go that route again if I want to use this.
 

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Discussion Starter #887
I did two jl slash series 800/8s going post amp into the amps
With focal flax replacements and it was so nice sounding

No dsp , just channel for channel hi level in to 13channels


Needless to say, the factory dsp work was pretty good
And hi level out of factory amp wasn’t that horrible.

Pretty nice system definitely.
 

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Found a glitch tonight. Idk if its REW or the minidsp plug in but if you pick the minidsp 2x4hd to export to in Rew. It will halve all frequencies when importing to the plug in..which is obviously bad.

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Found a glitch tonight. Idk if its REW or the minidsp plug in but if you pick the minidsp 2x4hd to export to in Rew. It will halve all frequencies when importing to the plug in..which is obviously bad.

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It's probably REW, use the generic eq target and specify the correct sample rate, that's probably where the error is. You using the Beta version?
 

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The minidsp 96k only had 6 outs tho. So that kinda ruins the point of it..

Its fine. i can just input them manually into the Plugin. Its not That big of a deal.

I do find the there is some discrepancies between what Rew shows and what Dirac shows. I believe you said something about it ignoring Modes? Though im seeing differences in the higher frequencies as well. I have a feeling it has to do with levels being different than they are in Rew. Even when im leaving them alone. I have it set as a 2+sub. So the levels between drivers may be a little different. Doesn't exactly matter as the Dirac EQ takes care of it anyway.

I went back to the way i used to set T/a with using nulls. It helps that my Horns and Midbass are like right the fuck on top of eachother so T/a can be off and still within margin of error.

Im finding that i Really like the wisdom curve that comes inside the Dirac files, as well as putting a high shelf filter on 1k with a gentle slope.

I have this Helix dsp.2 just sitting on my desk now. What a paperweight next to this Dirac :p

All sounds perrrrrrrrtyyyy damnnnnn gooooood.

I guess i won't be mad at Oab for getting my hyped up when i had cash burning a hole in my pocket....
 

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The minidsp 96k only had 6 outs tho. So that kinda ruins the point of it..



Its fine. i can just input them manually into the Plugin. Its not That big of a deal.



I do find the there is some discrepancies between what Rew shows and what Dirac shows. I believe you said something about it ignoring Modes? Though im seeing differences in the higher frequencies as well. I have a feeling it has to do with levels being different than they are in Rew. Even when im leaving them alone. I have it set as a 2+sub. So the levels between drivers may be a little different. Doesn't exactly matter as the Dirac EQ takes care of it anyway.



I went back to the way i used to set T/a with using nulls. It helps that my Horns and Midbass are like right the fuck on top of eachother so T/a can be off and still within margin of error.



Im finding that i Really like the wisdom curve that comes inside the Dirac files, as well as putting a high shelf filter on 1k with a gentle slope.



I have this Helix dsp.2 just sitting on my desk now. What a paperweight next to this Dirac



All sounds perrrrrrrrtyyyy damnnnnn gooooood.



I guess i won't be mad at Oab for getting my hyped up when i had cash burning a hole in my pocket....
Use the generic eq setting then specify the correct sample rate when exporting, you'll have to uncheck 10 of the eq bands before optimization.
 

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MiniDSP has a firmware upgrade for the C-DSP 8x12 DL which is supposed to be handling sub volume control issues.
 
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MiniDSP has a firmware upgrade for the C-DSP 8x12 DL which is supposed to be handling sub volume control issues.
I loaded the firmware update & new revision plug-in 2 days ago. All is working well so far... but never really had the subwoofer volume control issues as I don't have the subchannel assigned in the plugin for it. I do appreciate that the "IP address" thingy scrolls with the rest of the screen now.
 
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So I want to use a Z-400.2LX as a sub amp but it doesn't have a remote bass knob option. I like having a bass knob... How functional is the minidsp 8x12 bass knob? It spins endlessly, so I assume to reset it back to zero you just tap out of mode 1 into mode 2, then back to mode 1 again to reset the sub gain to baseline... Anyone using this feature and do they miss a dedicated bass knob? I also have a Z3KD with an actual bass knob, which I may go with depending on user feedback on the minidsp bass knob workaround.
 

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[email protected]&$ your right

Forgot about that, maybe a feature request for future
Updates .


Okay than,

In that instance you could add a 20hz HPF in biquad to all other speakers under advanced in one of the peq banks , you would have to use the minidsp biquad spreadsheet or online calc to make it and just cut and past the coefficients into a peq slot s for all output channels


The only reason he wants to do that in the input is so all speakers exhibit the same phase shift so it becomes inaudible

So yeah that would work , you would loose a peq slot but with Dirac it’s nil anyways for the most part.

So if my sub amp applies a non-defeatable 24db/oct SSF at 10hz, to minimize the phase shift I should apply a similar biquad to all outputs except the sub in the CDSP?
 

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A question on Bass Management and the high pass filter setting....


Before I ask the question, I need to review a scenario in car audio subwoofer setup for some background info.

Generally, a good way to setup a subwoofer is to tune the main speakers first and get them all dialed and running well as a group, and then define the subwoofer and the main speaker group as a 2-way system and tune the sub to match the mains. This method would mean that we have optimized our midbass to midrange crossover region well and have a good blend that maintains good phase alignment through the crossover point.

Now, we combine the subwoofer with our midbass and set the sub crossover point so that it blends well with our midbass. Good phase alignment through the crossover point, etc...

At this point, some of us might be finished. But some people might have reason to want to add a subsonic filter to their subwoofer for protection. Maybe they have a ported sub, or maybe they are IB and have a sub with a strong motor that can easily reach XMax if not careful. Whatever the reason for wanting a subsonic filter, there is always a problem presented by adding a high pass filter to just the subwoofer channel.

That problem is that when we put a high pass filter on a channel, there is a phase effect. For example, a Linkwitz 24 dB high pass filter at 20 Hz will cause a forward rotation of phase of 180 degrees at 20 hz. That forward rotation of phase at 20Hz will affect frquencies both above and below 20Hz, and it can even affect the phase response in the crossover point with the midbass. (60 Hz, for example, like many of us use)


What is the solution to this problem?

The solution is actually very simple in theory, but not simple because most car audio DSPs do not give us the tools we need to fix it.

The solution is that we need crossover filters on the inputs of the DSP, not just on the outputs. If we add a 20 Hz high pass filter to the input of the DSP, that means the forward rotation of phase caused by the high pass would get applied to all of the speakers in the system equally. If all speakers get phase shifted by the same amount, then the net effect is that there would be no phase offset created between different drivers. We could have our subsonic filter "cake" and eat it, too.



Now..... back to Bass Management.


It looks to me like the Bass Management is designed to work as an input highpass and lowpass. So, could we set the high pass to 20Hz as a subsonic filter that gets applied to all speakers in the car? A system-wide high pass, in other words.

Subterfuse you've made several excellent contributions to this thread and I really appreciate your detailed and thoughtful posts. I'm still in the process of installing my amps and speakers but the CDSP-8x12 DL is already in. Your posts in this thread will be extremely helpful as a reference while I'm setting up and tuning with the CDSP.

I'm wanting to install a Zapco Z3KD for the sub but the amp has a built-in, non defeatable 24db/oct SSF that can be adjusted all the way down to 10hz. I hadn't considered it before, but now I'm having concerns about the phase rotation you mentioned in the above post.

I can think of a few workarounds to potentially minimize or mitigate this complication:

(1) My head unit has an adjustable HPF that can be applied to the SPDIF out as low as 20hz. If I apply the HPF from the HU at 20hz, so the DSP sees only a 20hz-20khz signal at the inputs, will the additional SSF at 10hz on the subwoofer (which is below the previously applied 20hz HPF) still potentially alter the phase at 60hz? Or will the forward rotation of phase be mostly cancelled out by the HPF at 20hz earlier in the chain?

(2) Another option would be to simply use another sub amp that doesn't have the non-defeatable SSF.

(3) Then there's the biquad approach or the workaround Oabeieo suggested.

(4) Alternatively, did you ever pursue finding a workaround using just the CDSP 8x12DL with it's bass management applying a SSF to all inputs? Ideally I would find a way to apply a 10hz SSF to all inputs EXCEPT the subwoofer, and use the 10hz SSF on the amp to bring the subwoofer channel in line.

My guess is that unless I can find a simple solution to this issue, I will likely install both amps in a temporary fashion, set up with the Z3KD on the sub and get it to sound the best I can. Save a preset. Then set up with the Z-400.2 LX on the sub and get it to sound the best I can. Save a preset, compare the two and go from there.
 
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