# MiniDSP 2x4 as 20-band (per ch.) PEQ



## StanDingwave (Feb 25, 2012)

Perhaps this is not revolutionary, but I am quite pleased with myself nonetheless :sarcastic:

Currently I am experimenting with using a MiniDSP 2x4 with "2-way-advanced" (Parametric EQ) for a combination of equalizing Bose 901 II and room correction, using REW as the source for analysis and the biquads. 

lddude: Set aside for a moment, if you can, your audiophile snootiness at my rather modest loudspeakers, as well as my daring to discuss a budget electronic gear that has electrolytic :rolleyesno: capacitors on the inputs and the outputs. Haven't these Far Easterners ever heard of Audio Note or Mundorf? 

If one goes solely by the docs, and assuming use as a two-channel EQ, the MiniDSP info would have you believe that you have 6 bands PEQ on input and 6 on each channel's output. It occured to me to try, and it seems to work, to use the up to 8 PEQs of the "crossover" section for regular peaking filters. The lazy way: you can cut and paste 6 from REW, a bit harder, you can use the supplied biquad calc of the plug-in to calculate the last 2 "extra" biquads. The high-pass is set to "bypass". Do the same for both crossovers.

Unless I am missing something, this is a sneaky way to get 18 filters per channel (if you're lazy) or 20 (with a bit mre work). :mooooh:

If anyone really cares, I could post my travails in EQ-ing the 901's.

:1eye: Our country needs more atomic power plants!


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## mppatt01 (Jan 15, 2012)

StanDingwave said:


> Perhaps this is not revolutionary, but I am quite pleased with myself nonetheless :sarcastic:
> 
> Currently I am experimenting with using a MiniDSP 2x4 with "2-way-advanced" (Parametric EQ) for a combination of equalizing Bose 901 II and room correction, using REW as the source for analysis and the biquads.
> 
> ...


I didn't realize you could get so many filters from the minisdp. I've read their site a couple of times but am still unclear on the total capabilities of it. 

Also, hello from just a bit south of you.


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## StanDingwave (Feb 25, 2012)

Yes, I thought it was neat too. I will probably suggest to MiniDSP they note this capability in their documentation.


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## SAC (Dec 3, 2009)

Except for the modal behavior, little exists in a Bose 901 environment that is minimum phase in the specular region. As the fundamental design goal was to introduce additional early arriving indirect non-minimum phase signals that superpose with the direct signal to create polar lobing and derivative comb filtering. And to that end, EQ is not a viable solution for correcting source-room interaction of non-minimum phase conditions - of which it was the goal of the Bose 901 to create in the first place.

And it seems a bit odd to try to defeat the fundamental design goal of the speaker. And if one does wish to do that, I might instead suggest using treatment that is up to the job.


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## Wayne A. Pflughaupt (Apr 13, 2006)

StanDingwave said:


> Unless I am missing something, this is a sneaky way to get 18 filters per channel (if you're lazy) or 20 (with a bit mre work). :mooooh:
> 
> If anyone really cares, I could post my travails in EQ-ing the 901's.


Nice trick if it works I guess, but anyone who needs that many filters is going overboard.

Sounds like you’re having trouble EQing these speakers, and if so SAC’s post probably adequately explains why. Aren’t the 901s the ones that came with an outboard EQ box? If so you’re probably going to have the best results with the mini DSP by just mimicking the stock EQ, which is basically a tone control affecting broad ranges of the frequency spectrum, for the upper frequencies. For the lower frequencies you might have good results using parametric equalization, but given the complex radiating properties of these speakers, that should rely on careful listening tests to make sure any EQ applied is actually delivering a sonic improvement.

Regards,
Wayne


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## SAC (Dec 3, 2009)

The outboard box for the 901's was more than an EQ, as large portions of the spectra were synthesized, as a 3 inch driver was not capable of natively producing them with sufficient gain.

What is EQ'd is the direct signal fed to each of the drivers, not the interaction of the drivers or of the room-loudspeaker.

At least they addressed ONE aspect of the speaker's design 'properly'. Now how the average user 'used' it...all bets are off...


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## StanDingwave (Feb 25, 2012)

I generally agree with Wayne: my goal is mainly to tame the peaks in the "bass" (modal? nodal?) regions and not worry about the nulls. Probably to mimic the Bose EQ would be a good idea, I could do a frequency sweep of the unit to REW. Some of SAC's comments confuse me: I thought the Bose EQ is just an EQ, albeit with very big boosts at low and high frequencies. The 3" drivers are actually 4 1/2 " if I recall. Perhaps I am using too many EQ's, but "nothing exceeds like excess!":bigsmile:


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