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Discussion Starter #21

Quote:
Originally Posted by Martycool007  /t/1501830/equalizer-for-the-ulf#post_24002859


I tried reading that thread that you linked on the MiniDsp forum, but for some reason my phone cut the screen in half and I could only read parts of it. What exactly is the issue with the MiniDsp boosting the below 20hz content? Can this be worked around in the software? I really hate to hear this as I ordered a MiniDsp 2 by 4 balanced with the HD plug in for possibly providing boost for some sealed subs that I am building. Any info on this matter would be great!

The filter behaviour under 20 Hz is unstable. According to this post the reason is the high sample rate in combination with a fixed point DSP. There is a 48 kHz version of the SubEQ plugin, but I don't know how stable it is.


And let's face it: we are freaks. The 99% don't care about
 

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Quote:
Originally Posted by FoLLgoTT  /t/1501830/equalizer-for-the-ulf#post_24004247


The filter behaviour under 20 Hz is unstable. According to this post the reason is the high sample rate in combination with a fixed point DSP. There is a 48 kHz version of the SubEQ plugin, but I don't know how stable it is.


And let's face it: we are freaks. The 99% don't care about
that's only for the 96kHz units. the 8 channel output ones, not the 4 channel which are 24kHz. those units may have voltage limitations though for some setups
 

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Quote:
Originally Posted by notnyt  /t/1501830/equalizer-for-the-ulf#post_24004698



that's only for the 96kHz units. the 8 channel output ones, not the 4 channel which are 24kHz. those units may have voltage limitations though for some setups

So can you, or anyone else, confirm that it is possible to boost the sub-20hz content in a MiniDsp 2 by 4 balanced with HD plug-in, at say 16hz and up?


I was planning to build some sealed subs with my existing Dayton HO18's, and was planning to use this MiniDsp 2 by 4 balanced with advanced plug-in to boost the sub-20hz levels, but now I am not sure if that is a good way to do it?!
 

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Quote:
Originally Posted by bossobass  /t/1501830/equalizer-for-the-ulf#post_23999545


Yes, analog beats digital for ULF. The signal arrives in analog. Converting to to digital and then back to analog is very dependent on the ADC/DAC quality, not the bits used for processing. Units like the DCX can work, but they roll off sooner and do not retain the signal integrity in my experiences, which span a decade.


Desertdome is a top notch guy when it comes to HTPC systems and the JRiver stuff. I haven't tried it, so I would definitely defer to him on that and I would implicitly trust what he has to say about it.



In any case, I have a couple mono Bassis units from Marchand and I can custom build an SEQSS if you can provide the right data. The Marchand is measured flat to 2 Hz (+0/-3dB) and the SEQSS has virtually no roll off.


Ping me if interested.

Marchand or SEQSS accept balanced inputs?


JSS
 

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Quote:
Originally Posted by maxmercy  /t/1501830/equalizer-for-the-ulf#post_24006870


Marchand or SEQSS accept balanced inputs?


JSS

The Marchand can be purchased I believe with balanced or a RCA unit can be converter to balanced (I had to do this to mine).
 

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Quote:
Originally Posted by maxmercy  /t/1501830/equalizer-for-the-ulf#post_24006870


Marchand or SEQSS accept balanced inputs?


JSS

Phil Marchand will build anything you ask him (and are willing to pay him) to build.



I chose RCA input for the SEQSS because going with XLR in excludes 90% of the market for the hardware. I chose balanced out simply because the amplifiers used are assumed to be balanced in.


Balanced through is useful in eliminating noise. This requires properly internally grounded hardware on both ends of the cable, which, over 45 years as a live and recording musician, I have had many first hand experiences demonstrating that that is not the case.


With RCA in, if the result is that there is unacceptable noise, an RCA transformer adapter for RCA jack-equipped preamps or an XLR>RCA transforming adapter for balanced out jack-equipped preamps is the correct option.


Technically, this is the 2nd best way to achieve noise-free operation, but in the app we're involved with, there is typically no problem with noise and thus no advantage either way.


The nonsense floating around that XLR somehow magically audibly enhances the actual signal is just that.
 

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Quote:
Originally Posted by bossobass  /t/1501830/equalizer-for-the-ulf#post_24007812


Phil Marchand will build anything you ask him (and are willing to pay him) to build.

Lol, really? Does this still apply today?


I know my emails from a year or two ago have gone unanswered. At least, all the ones after the first email where I was detailing what I wanted and was going to buy.
 

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Discussion Starter #30
Here are the measurements of the Klein + Hummel Pro C28. Its input can be switched between electrical and transformer. It is pretty flat down to 2 Hz. I never saw a digital device that got this low. The IIR shelving filter at 10 Hz looks pretty good, too. I have to measure my new subwoofers and check if this controller fits my requirement.

 

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Quote:
Originally Posted by FoLLgoTT  /t/1501830/equalizer-for-the-ulf/0_100#post_24020430


I asked miniDSP team about the precision issue with the 2x8 board and they answered that it is already fixed. Maybe someone can post measurements with a PEQ under 20 Hz?

I'll measure mine when I redo my system, might be a few weeks though. Hopefully someone else can do it before then. I'm just not sure I have my current filters saved anywhere.


What they considered fixed, I still considered ****. Though I'll try the 48khz plugin instead of the 96 and see. Them even admitting there was an issue took lots of fighting.


If anyone has one, run it through a loopback with various filters around 10hz and see if they're still wacky.
 

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Discussion Starter #33
I'm a lucky bastard! I don't need any equalizing under 20 Hz!



Today I did a test measurement with 6 drivers in 1/4 and 3/4 placement of wall width. There was no absorber on the back wall and the microphone was standing in the middle of the room (no first order length mode). The measurement was SPL calibrated and corecction files for sound card and microphone were applied.




I knew that my room gain is pretty high. All boundaries are very solid. Without equalizer I reach 3,4 Hz. Amplifier was a Sanway FP14000. My copy is flat to under 3 Hz.

 

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Quote:
Originally Posted by FoLLgoTT  /t/1501830/equalizer-for-the-ulf#post_24007645


My Behringer Ultracurve DEQ2496 looks pretty good at the low end. But the controls can only be set to 20 Hz. This is the lowest shelve I can configure.

Quote:
Originally Posted by bossobass  /t/1501830/equalizer-for-the-ulf#post_24002877


Ah, I hadn't thought of the loss in precision with high sampling rates. It's true, to get full BW you have to have 40k sampling which, after spreading out across DC-20k Hz leaves very low precision in the SW BW. Add that to the obviously low cost ADC/DAC and the power supply solutions offered and it isn't a good prospect on paper.


Here's various analog and digital solutions I've measured after dialing in the proper curves for my current system and 10 dB boost:




When you add the AVR and the amplifier roll off, this completely explains why most people do not have strong
 

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Quote:
Originally Posted by Scott Simonian  /t/1501830/equalizer-for-the-ulf/0_100#post_24246140


Heh. Welcome back.
Look forward to what you find.

Thanks. I already flashed the new firmware, I just need to find a few minutes to test. My subs are currently not EQ'd at all. Not going to bother until I finish the rest. The 96khz was pretty brutal screwing up the curves under 20hz. Lets hope this isn't as bad.
 

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Quote:
Originally Posted by FoLLgoTT  /t/1501830/equalizer-for-the-ulf/0_100#post_23997132


My subwoofer wall will be built next weekend and I'm still looking for a suitable equalizer for the

- Marchand WM8 -> rather expensive

- MiniDSP -> reported to not work well in the ULF and may have clipping problems

- self-made circuit board with Linkwitz transform -> only one fixed preset

- Bossobass' SEQSS -> availability?


Are there any other linkwitz transforming equalizers? Or any digital equalizers which can be configured for under 20 Hz?
The FBQ2496 has filters wide enough [5 octaves] to effect an LT type curve. It can be simulated to a degree in WinISD Pro. MiniDSP and Winisd Pro work pretty well together, at least for me. Boosting 20Hz at Q=.182 will lift from 3 - 113 Hz. Then a filter higher up at about 130Hz set for the same width will attenuate down to 23Hz. So as you can see, the cut-correction would not effect what you have boosted below 20Hz. Of course you can experiment with the top center and cut level, but a 8 - 10 dB boost @ 20Hz would be corrected with 8 - 10 dB of attenuation at the 130Hz center...or thereabouts, depending on FR sweeps.


I would not go through the trouble of building circuits. Not worth it really. The aforementioned technique has been used by me, and the difference between an actual Linkwitz solution with MiniDSP and the 1124DSP was not that different, just more extension on the bottom because the 1124 only has 2 octave filter widths, making the above strategy impossible. If you want razor thin accuracy then I suppose you could subject yourself to the potential rigours and consternation omnipresent when building a circuit board but I personally would not bother.


As for the ULF, the MiniDSP comes in two options: .9 and 2Vrms input. Maybe the clipping has to do with the wrong version being used?
 
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