# miniDSP 2x4 balanced vs. HD?



## Arv

First post here, excuse me if I missed something obvious.

I’ve been doing some research lately and there’s lots of outdated and conflicting material out there which makes it confusing for DSP newbies like me, I just want to get the purchase over with today! ?So i can concentrate on the model that I get.


I have a Denon X4300H with Audyssey Sub EQ HT with 2 sub outs.
Ported 12" sub tuned to 18 Hz. (plan to run at 18hz - 50hz) front right corner 16.7 ft from MLP per Audyssey
2 x15" ported MBMs (50Hz-150Hz) up front center, not yet in place, recently acquired CV speakers.
12" ported MBM behind MLP near field 3.5ft per Audyssey (50-100/150hz??? Any suggestions?)
L/R towers with dual 8” - crossed at 40Hz. per Audyssey but/or 50hz better to match sub/MBM cross?
Aura bass shakers that I might no longer use.
Sub amps: Dayton HPSA100R bridged, Audiosource Amp3 bridged, AMC2100 bridged - all non-pro for now.


I really want to get the balanced version but the 7.5 ms delay is an issue due to the 13.2 ft. net distance between main sub in front and NF sub. I can scoot up my MLP but I don’t think a foot or two would still be enough even if I add another low pass above the crossover point to introduce another delay. I really do not want to use the loopback method because I might need all 4 outputs. Would setting the AVR sub out 1 that goes into input 1 with a distance of 0 for the front sub, and sub out 2 that goes into input 2 with a distance of 13.2ft. to feed the MLP sub work? Of course this needs to be tweaked WRT to the other speakers. I’m also really confused whether to run Audyssey auto correction first or tweak in miniDSP for my case :-(



I rather not spend the extra money on the HD but I’m also concerned about the 96k sampling rate, is this really a big issue for subs? If not I’m just going to buy the HD unless I can get the balanced to work for my application.
I know the HD has a lot more bells and whistles but I have not learned what these things can do, are they worth the extra money?



Any pros/cons I could have missed (aside from the published specs like max. voltages, # of PEQs, etc...)?



Thanks in advance for the helping a miniDSP newbie out!


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## Arv

Anyone?
thanks!


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## Wayne A. Pflughaupt

Are you saying that your receiver can’t deal with 7.5 ms + 13.5 ms delay?

I’ve never heard that the 96 kHz sampling rate is a problem. I don’t see a reason to get the HD unless you need the added features.

Regards,
Wayne


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## Arv

Wayne A. Pflughaupt said:


> Are you saying that your receiver can’t deal with 7.5 ms + 13.5 ms delay?
> 
> I’ve never heard that the 96 kHz sampling rate is a problem. I don’t see a reason to get the HD unless you need the added features.
> 
> Regards,
> Wayne


Hi Wayne,
So one thing I'm confused about (might be because of the conflicting info out there) is whether I should run Audy then work on miniDSP or the other way around. IF I should run Audy auto correction first then the distance/delay problem is solved since Audy will set the delays. 

I can live without the other features that HD offers over balanced but I want it done correctly with the least cost with this miniDSP implementation. If I have to spend a bit more for the HD then so be it.

Thanks!


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## Arv

Oh apparently, the 48 sampling rate that the balanced does is more accurate down in the low frequencies which I will be dealing with.


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## Arv

Bump, anymore comments, want to purchase something today so I can have it in time for the weekend.


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## AustinJerry

If I understand correctly, you have a total of four subs, and you want to use a MiniDSP device to consolidate the subs for use with your AVR and Audyssey. My approach would be:

1. Time-align the four subs. Using the delay settings on each of the four channels of a 2x4, you can time-align the four subs. The 13.2 net distance will require an 11.7ms delay setting, which means the 2x4HD will be required. Use REW's Impulse Response measurement to check and fine-tune the alignment.

2. Once you have the subs time-aligned, measure the combined sub signal using REW. Use the combined measurement as input to REW's EQ tool and generate PEQ filters to get the response as flat as possible. The PEQ filters can be exported and loaded directly into the 2x4HD.

3. Once you have applied the PEQ, re-measure using REW to make sure the PEQ is achieving the desired response.

4. The combined sub signal is now ready for Audyssey room calibration. Configure the AVR for ONE sub, and route the Sub1 output to the 2x4HD. Audyssey will measure, time-align, and apply correction to the combined sub signal.

5. Once Audyssey has completed, re-measure with REW to see what improvement Audyssey has achieved.

I don't think 48KHz vs. 96KHz makes any difference on the sub channel.


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## darrellh44

AustinJerry said:


> If I understand correctly, you have a total of four subs, and you want to use a MiniDSP device to consolidate the subs for use with your AVR and Audyssey. My approach would be:
> 
> 1. Time-align the four subs. Using the delay settings on each of the four channels of a 2x4, you can time-align the four subs. The 13.2 net distance will require an 11.7ms delay setting, which means the 2x4HD will be required. Use REW's Impulse Response measurement to check and fine-tune the alignment.
> 
> 2. Once you have the subs time-aligned, measure the combined sub signal using REW. Use the combined measurement as input to REW's EQ tool and generate PEQ filters to get the response as flat as possible. The PEQ filters can be exported and loaded directly into the 2x4HD.
> 
> 3. Once you have applied the PEQ, re-measure using REW to make sure the PEQ is achieving the desired response.
> 
> 4. The combined sub signal is now ready for Audyssey room calibration. Configure the AVR for ONE sub, and route the Sub1 output to the 2x4HD. Audyssey will measure, time-align, and apply correction to the combined sub signal.
> 
> 5. Once Audyssey has completed, re-measure with REW to see what improvement Audyssey has achieved.
> 
> I don't think 48KHz vs. 96KHz makes any difference on the sub channel.


Hi Jerry,

I was wondering if you have an opinion on using MSO in place of the time-alignment steps you describe above. I only have two subs in my room (front-centered and rear-centered), so having a program that results in more even room SPL certainly has its merits. However, I'm more interested in getting tighter bass with more TR at the MLP than getting decent bass at all listening positions. Can I get you to comment on the two approaches?

Thanks,
Darrell


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## AustinJerry

MSO is designed specifically to provide more uniform bass response across multiple listening positions. I experimented with MSO, but i found that I was always sacrificing the MLP response in favor or the more even response. I discussed my results with AndyC (the author of MSO), and he agreed that MSO may not always provide the best response for a single listening spot.

So, if you have the time, I encourage you to try MSO, but be ready to spend some time on what is a rather time-consuming process. If you only care about the MLP, the approach I described in a previous post my be your best answer.


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## darrellh44

AustinJerry said:


> MSO is designed specifically to provide more uniform bass response across multiple listening positions. I experimented with MSO, but i found that I was always sacrificing the MLP response in favor or the more even response. I discussed my results with AndyC (the author of MSO), and he agreed that MSO may not always provide the best response for a single listening spot.
> 
> So, if you have the time, I encourage you to try MSO, but be ready to spend some time on what is a rather time-consuming process. If you only care about the MLP, the approach I described in a previous post my be your best answer.
> 
> Thanks,
> Darrell


Great, thanks for the info.


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## lombarmj

AustinJerry , first thank you for the awesome REW and MiniDSP tutorials and your ongoing guidance!

Wondering about your thoughts on using PEQ in MiniDSP in addition to room correction (in my case DiracLive). My gut says to just let Dirac do the EQ on the premise that Dirac's mixed-phase filters would be more sophisticated than REW's filter settings and MiniDSP implementation.

I've tried doing PEQ on each sub individually; PEQ on overall response with both subs playing; and combination of both ... and each of these scenarios followed by Dirac. I feel like I get better response with just Dirac. But wondering if there is a technical premise for using PEQ also.

Thanks!


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## AustinJerry

Like you, I think Dirac probably does a better job than PEQ from REW. However, in some cases, applying PEW prior to running the Dirac Live calibration may produce even better results. My recommendations:

- Measure the combined sub response and use the combined measurement to create the REW PEQ filters.
- Apply the PEQ filters to the combined sub signal. Note I don’t recommend individual PEQ—this does not necessarily provide the best improvement.
- Run the Dirac Live calibration.
- Measure the results and compare with a Dirac calibration without PEQ.
- Go with the best result.


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## lombarmj

Thanks Jerry! I have done more experiments, and found that indeed in my scenario doing some overall PEQ in MiniDSP prior to Dirac does work best. 

I should mention my setup is somewhat unusual in that I'm using the LFE from the preamp into MiniDSP to drive two Outlaw subs (front and rear of the room) and a Magnepan DWM. I cross the subs to operate below 50Hz LR24db/Octave. The DWM operates above 40Hz LR 48db/Octave, and below 300Hz LR24db/Octave. Crossovers were determined by experiment and measurement for smoothest response. I did some time delay adjustment and had to fix polarity. In the end I had to do considerable experimentation with positioning the DWM to get phase at the crossover points to align. Note the steep roll off of the DWM is to prevent sub-30Hz LFE from rattling the diaphragm against the magnets!

Since the subs are more efficient than the DWM, I gain matched best I could and then did just enough PEQ to get the peaks of the subs down to similar amplitude as the DWM. This allowed Dirac to do a better job, especially with the upper range of the DWM near 200Hz where it rolls off.

DWM covers my CC5 center below 200Hz and MC1 surrounds below 80Hz. It also helps smooth the transition where the 3.7 mains cross to the subs at 40Hz.

Thanks again! 

p.s. Hoping for Dirac Bass Management to be available when Dirac 2.0 comes to the Emotiva XMC-2.


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## AustinJerry

Looks like you have followed what I always recommend—careful experimentation with all the options available to you. This approach will usually produce good results. And yes, all Dirac Live users are anticipating the Dirac bass management solution. I am a MiniDSP 88A user, and am still waiting for a Dirac 2.0 support announcement. In the meantime, I am pretty happy with what I have.


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## lombarmj

Some pictures. Frequency/Amplitude response of all speakers with DiracLive room correction. LFE represents MiniDSP output of two subs plus DWM crossed over as shown and PEQ on combined.


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