# miniDSP for three-way speaker



## erwinbel (Mar 23, 2010)

Hi,

I want to purchase the mini-DSP to act as a crossover for my three-way LCR build. Already have the UMIK-1.

Thus I need 9 (analogue) outputs. I'd opt for 24/96 balanced which means I need to purchase 2x the 2x8 KIT and 2x box for 2x8 KIT, correct? Here's the order sheet:

_*DIGITAL OPTION (DIGI-FP) NO THANKS
CONTROL ACCESSORIES NO THANKS
FRONT PANEL USB ADD FRONT PANEL ACCESSORY
ADD A UMIK-1 NO THANKS*_

Do I buy [1x] 10x10 plug-in (for both KIT's) or [2x] 4x10 (one for each KIT)

Anything else?
Thanks!


BTW, thinking out of the box, theoretically, would it be possible to use the free 7th and 8th output to hook up the two subs I have? Making it 4-way.


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## ajinfla (May 10, 2009)

erwinbel said:


> Thus I need 9 (analogue) outputs. I'd opt for 24/96 balanced...


Hi Erwinbel,

I'm a bit confused by the 2nd statement. You want a AES/EBU digital input for your front 3 channels?

cheers


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## erwinbel (Mar 23, 2010)

No, I do not. I will get a pre-pro with XLR outputs and connect the LCR XLR to the miniDSP. I have no idea why I would ever need the AES/EBU anyway?


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## ajinfla (May 10, 2009)

For digital transmission. That's why I was puzzled by your "*24/96* balanced" statement.
Have you considered using a single MiniDSP 2x4 (balanced) for each channel? They can be configured for mono 4 way and are only around $100-120 each.
Or better yet, since this is a HT, not stadium, using unbalanced MiniDSP 2x4 and your Emotivas unbalanced outputs? Are the amps pro, with balanced inputs?

Btw, like your OB Jamos. Have a friend here with R909s also.

cheers


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

Not sure why this is in the REW forum and not the DIY Speakers or Equalizers forum, but I’ve heard numerous reports of the unbalanced miniDSP version having low headroom capabilities and often not able to handle the main outputs of many home theater receivers.

Regards,
Wayne


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## Ted Clamstruck (Mar 26, 2014)

Wayne A. Pflughaupt said:


> Not sure why this is in the REW forum and not the DIY Speakers or Equalizers forum, but I’ve heard numerous reports of the unbalanced miniDSP version having low headroom capabilities and often not able to handle the main outputs of many home theater receivers.


The unbalanced 2x4 has a maximum output of 0.9 Volts RMS, so if you use it with an amp having an input sensitivity greater than 0.9 Volts RMS, the unbalanced miniDSP 2x4 won't be able to drive it to full power.

Although there is no universal standard for power amp gain, one spec that's often adhered to is the THX gain spec, which is 29 dB. This represents a voltage ratio of 28.18x. So an amp adhering to this gain spec, when paired with the unbalanced miniDSP could only put out a maximum RMS voltage of 0.9 * 28.18 = 25.36 Volts RMS. That's 80.4 Watts into 8 Ohms. Any amp with higher output power into 8 Ohms needs to have a gain higher than the 29 dB THX spec, or its input sensitivity will be greater than 0.9 Volts RMS.

Another point of confusion is that the unbalanced miniDSP has an input sensitivity jumper that can be used to select an input sensitivity of 0.9 Volts RMS or 2.0 Volts RMS. But the maximum output voltage is 0.9 Volts RMS regardless. With the input sensitivity jumper set to 2.0 Volts RMS, it's actually attenuating its input signal by 20 * log10(0.9 / 2.0) dB or 6.9 dB.


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## erwinbel (Mar 23, 2010)

Thanks all. I just ordered the 2x8 kit in a rackmount box with front USB and the 4x10 pug-in since that is the only way to have 24/96 since the 10x10 is only 24/48.

This way I can control the Left and Right speaker, to start.

Sorry if this was in the wrong board...


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## ajinfla (May 10, 2009)

Ah, you must be referring to the internal processing. Sorry about my confusion. Also missed this was in REW forum since I caught it in "Unanswered posts".
Erwin, keep us updated on the project, sounds interesting. I actually bought a 2x4 (unbalanced RevB) a while back to quick-prototype speakers, but have yet to use it. Guess I better get started too.

cheers


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