kevmurray

I've been playing around with a few of these for a couple weeks now and wondered if anyone else is using them?

lpchouinard

no, waiting for someone to sell it for cheap to try them

AAAAAAA

iTrader: (7)

You got some cool toys there Kevin as usual.

Here is a pretty big thread on em.

MiniDSP: An excellent alternative! - DIYMA.com

They are pretty sweet.

Haunz

iTrader: (3)

Wow.. looks crazy awsome!!!

I looked around the website briefly, and it appears that some amount of work/skill is required to implement them...


Kevin, please tell me more about your experience with these units and what you had to do to get them up and running in your specific application !!!

kevmurray

lol, sorry LP I think I'm gonna keep these They're pretty cool and besides, they're cheap anyway. I bought 2 to implement a 4 way crossover with parametric EQ and time delay for $200.

kevmurray

It was actually very easy. I got the one with the unbalanced input so I could use my home stereo patch cords for interconnect (RCA type). I had it up and running in about 10 minutes including software install. The configuration is done on a PC through a USB connection to the board. Once you have it configured the way you want you can unplug the USB cable and take it wherever you want to use it. You can also tweak things on the fly with the board in-system.

I bought the 4way crossover firmware so I needed 2 boards to cover both left and right. There are digital inputs and outputs (I2S format) so if you have the ability you can bit stream the audio in to bypass the pointless A2D/DA conversions. The sound quality is plenty good as far as I'm concerned but if you wanted you could use your own DAC. It would have to be able take an I2S signal or you would need a converter (which is available from MiniDSP).

If you want to get into advanced DSP you can purchase firmware that allows you to use your own filter coefficients. I didn't need it so didn't bother but if you're interested I can point you to free software that will generate the coefficients for you. Then you simply load them onto the MiniDSP and it does the convolution.

Here are a few pics of my settings and the measured results. Note the 60 Hz bump, that is a result of how I powered it and not the fault of the MiniDSP.





Edit: One more thing I forgot to mention: Notice the output is ~9dB down from the reference (input). This is just the way it's designed. It provides headroom for the EQ sections. I will test it to see what the maximum output voltage is.

kevmurray

Here is a distortion graph from a test I did today. The upper (left channel) plot is the loopback and is the limit of my test setup. I use an Azus Zonar sound card which has a very low published SNR spec. The lower plot is the MiniDSP performance. The window to the top right gives THD respectively.

One disappointing thing about this board is the maximum output voltage is only 1 volt rms. It's really not a big issue since the gain can be raised on the amps but it's still disappointing.

lpchouinard

can't you use the amp version to use it as a line driver?

kevmurray

Here is a plot of the output noise - zero volts input.

kevmurray

Inter Modulation Distortion (IMD):