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-   -   Any measurements on the MiniDSP (https://www.diyaudio.com/forums/minidsp/175810-measurements-minidsp.html)

doug20 22nd October 2010 12:35 AM

Any measurements on the MiniDSP
 
has anyone did the measurements on the MiniDSP? Something like a simple loop back test like we do with sound cards when using measurement tools like HOLM.

I would love to see some. I curious about the MiniDSP performance overall and also what it does under 20Hz. I can use it as a SSF (Shelf filter and boost) but I need to know its measurements first.

Davey 22nd October 2010 02:23 AM

Doug,

I'm not sure what the question really is. Your question implies there is some sort of inherent frequency response limitation in the MiniDSP that would need to be understood and accounted for. It doesn't work that way.
You can assume the measured output will look exactly like the displayed curve in the MiniDSP software application.....Unless you force it into clipping with too much programmed boost or too much input voltage.

The specified 900mV output voltage limitation is accurate. I see the onset of clipping at about 905mV on my units.

The low frequency response is essentially flat to well below 20Hz. The output capacitor is a large value and should yield a near-DC turnover point with any nominal load.

Anyways, I've done quite a few measurements on mine. What do you want to see? I can program something specific if you'd like.

Cheers,

Dave.

doug20 22nd October 2010 11:37 AM

I just want to see the real response curve. All products have a inherent frequency response limitation and they all have noise floors to say the miniDSP does not work that way does not make sense since processors, Amps, DCX, Art cleanbox, SMS-1. eD EQ.2 (All products I have owned) and so on all have been measured to show the noise levels and overall response curve. Many have inherent Subsonic Filters, The Art Cleanbox rolls of serverly at 18Hz, the old version of the SMS-1 also rolled off early below 20Hz, I know of several amps and processors that have issues below 20Hz.

"well below 20Hz" is not meaningful enough when my two different sub systems (1 IB array and one multi-sealed disign) go into single digits. I want to know if the MiniDSP can be used as a manual EQ for high end sub systems that have no limits.

EDIT: I see you do comment that its near DC so that is great.

Any measurements you have done would be awesome. Im not the only one interested in seeing pretty graphs ;)

btw, your help on all this is very much appreciated!

Davey 22nd October 2010 02:52 PM

2 Attachment(s)
Doug,

Well, what I was trying to say (not very well I guess) is that you can consider the MiniDSP response flat....for all intents and purposes.

Anyways, here's a frequency response measurement on one of my MiniDSP units with no crossover/EQ/delay/etc programmed.....into a 10k ohm load.
(Mine is a Rev. B board which explains the -7.9db offset.)

Noise floor (yellow) with a few other measurements as references. Stock DCX2496 outputs (red), line outputs from EMU Tracker-Pre (violet), noise floor of my measuring system (aqua.)

Hope that helps.

Cheers,

Dave.

doug20 22nd October 2010 05:14 PM

Thank you for the measurements. Awesome comparisons.

pos 22nd October 2010 07:00 PM

I did not expect such good measurements, given that the DCX is specified for a 119dB dynamic range (analogue in and out) whereas the minidsp in only ">98dB".

That is quite impressive indeed! Is it done with analogue inputs and outputs?

Davey 22nd October 2010 08:26 PM

Well, you have to remember the DCX can spit out signal levels quite a bit higher than the MiniDSP. The majority of folks utilize the DCX2496 improperly, which is why there's such a variation of opinion on its performance. :)

Anyways, with any DSP devices of this type, gain structure has to be well understood and considered to achieve the best performance. Analog circuits don't (generally) have this limitation.

The MiniDSP has terrific test bench performance and the maximum signal levels are well considered (IMHO) to allow the units to be integrated successfully into a wide variety of systems.

Cheers,

Dave.

pos 22nd October 2010 08:48 PM

Would you have measurements at full output? Lets say using the digital input for both the DCX and the minidsp, and feeding them with a 0dB digital signal?
That is the way I use my DCX (with an SPL volume8 analog control), so that is how I would also use the minidsp (and specifically the balanced version)

Would you also happen to have distortion and maybe jitter measurements?

theresa 1st November 2010 10:39 AM

Turn down input or output?
 
Do I need to turn down the input and/or output level to avoid overloading? I'm using them with a Emotiva processor and amps. I don't want to set up for measuring it at the moment as I am just putting together a new system.

Davey 2nd November 2010 05:35 PM

Quote:

Originally Posted by theresa (https://www.diyaudio.com/forums/minidsp/175810-measurements-minidsp-post2350419.html#post2350419)
Do I need to turn down the input and/or output level to avoid overloading? I'm using them with a Emotiva processor and amps.

Probably not. The inputs/outputs of the MiniDSP modules are limited to 900mV, and that's right in the neighborhood of where most amplifiers would be delivering their rated power. So, if your MiniDSP modules are feeding the amplifiers directly I'd say your chances of clipping the MiniDSP outputs are near zero. This is what I was referring to with the "well considered maximum levels" comment. Unlike the DCX (and other commercial units) a multi-channel post-volume control is not necessary with the MiniDSP units.

The Emotiva power-amps have 32db voltage gain (which is a bit more than usual) so your MiniDSP working voltage levels would be a bit less than they would otherwise and reduce the chances of clipping even further.

Obviously, if programming large EQ boosts in the MiniDSP you might get into trouble, so you have to be aware.

Cheers,

Dave.


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