New miniDSP 2x8 / 4x10 card

JohnR · « **Reply #80 on:** 16 Aug 2011, 01:29 am »

pelliot... maybe you are giving up too easy? Why not work with a bit to see what you can get out of it? You don't get instant results with DSP. Use a sweep program to get more accurate measurements.

Davey · « **Reply #81 on:** 17 Aug 2011, 02:51 am »

Send it to me and I'll test it for you.

Dave.

pelliott321 · « **Reply #82 on:** 17 Aug 2011, 12:38 pm »

yes really broken here are some scope shots
1st is output of mid channel with no input. scope is at .5v/div so this is almost .5 volts of noise

next is 800hz pure sine wave from signal generator

next is output from mid channel with 800hz pure sine wave at input

I think this shows whats going on there is definitely a lot of noise from somewhere
when listening its not that obvious at first but the sound is just not clean, not very involving at all

JohnR · « **Reply #83 on:** 17 Aug 2011, 03:21 pm »

Hm

It would be interesting to see what the spectrum looks like... perhaps take Davey up on his offer?

Davey · « **Reply #84 on:** 18 Aug 2011, 12:05 am »

I certainly wouldn't throw it in the trash. Even if you can't come to an agreement regarding replacement/refund I would still send it back to them.
I'm not sure what the voltage gain of your power amp is, or the efficiency of your speakers, but that amount of noise should be much more than "not that obvious at first." It should be completely un-listenable....not just "not very involving at all."

If you're interested in a second pair of eyes and test equipment, I'd be glad to take a look at it.

Cheers,

Dave.

pelliott321 · « **Reply #85 on:** 18 Aug 2011, 07:26 pm »

Thanks for the offer Davey.
I finally got a response and an apology from miniDSP. Seems they have multiple people answering e-mails and they do not talk to each other. I suggest they come up with a case number approach.
Anyway I put the whole story out there again, and requested that they take a look at it. If it tests out then fine I will try to sell it and recoup some of my costs. If the board turns out to be defective then we will go from there
again I really appreciate your offer.

pelliott321 · « **Reply #86 on:** 21 Aug 2011, 01:20 pm »

well here we go again
I requested to send unit back on the 17th and I have yet to hear from miniDSP

JDUBS · « **Reply #87 on:** 22 Aug 2011, 04:23 am »

JohnR, do you know if the 5 bands of PEQ are available on each input channel or each output channel? If output channel, that seems like enough...but not sure if its for the input channel.

I like the idea of running i2s from source all the way through amplification (miniAMP).

Have you tried the REW integration yet? This is a big part of what has me interested.

Thanks,
Jim

JohnR · « **Reply #88 on:** 22 Aug 2011, 05:04 am »

Hi Jim, the 2x8 board has 5 on each input channel, and 5 on each output channel. The newer 8x8 board has 6 on each I believe although I've not used it myself.

The miniAMP is not plug and play with the 2x8 board, it's really designed to work with the small boards. On the 2x8 board only one (stereo) channel is brought out on the piggy back plugs, which is intended for the miniDIGI digital out. I don't know what would be involved in connecting a miniAMP to it. If you wanted more channels you'd have to wire directly into the board I believe. I do have a miniAMP with the small board here but haven't spent much time with it other than to confirm that it works.

I don't use the REW integration myself as I prefer to do it manually.

Hope that helps

JDUBS · « **Reply #89 on:** 22 Aug 2011, 08:13 pm »

Quote from: JohnR on 22 Aug 2011, 05:04 am

Hi Jim, the 2x8 board has 5 on each input channel, and 5 on each output channel. The newer 8x8 board has 6 on each I believe although I've not used it myself.

The miniAMP is not plug and play with the 2x8 board, it's really designed to work with the small boards. On the 2x8 board only one (stereo) channel is brought out on the piggy back plugs, which is intended for the miniDIGI digital out. I don't know what would be involved in connecting a miniAMP to it. If you wanted more channels you'd have to wire directly into the board I believe. I do have a miniAMP with the small board here but haven't spent much time with it other than to confirm that it works.

I don't use the REW integration myself as I prefer to do it manually.

Hope that helps

Thank you, John, very helpful. I'd love to run the miniAMP off of the miniDSP 2x8 or 8x8 for 4 channels in my active 3-way system - I'll post on miniDSP's forum to see if this is possible.

Thanks for the clarification on the bands. To verify further (for my specific 3-way active system), I believe this means that assuming 2 channels (left and right) for the bass amps / speakers, there are 5 bands for that frequency range (~20hz to 300hz) for each of those two channels? And then, for the mid-range, 2 more channels of output (left and right) with an additional 5 bands of PEQ for each channel? Same for the final two channels for the tweeters?

Also, the 5 PEQ bands on the input channels...are these over PEQ adjustments that can be made across the frequency spectrum, in addition to the PEQs done on the individual output channels?

Thanks again, John.

-Jim

JohnR · « **Reply #90 on:** 23 Aug 2011, 02:55 am »

The miniAMP question is answered here: http://www.minidsp.com/forum/10-minidsp-for-newbies/2305-re-is-2x8-compatable-with-miniamp?limit=6&start=48#2481

Yes to your questions, if I understand what you are asking - for more info perhaps the article will help: http://www.hifizine.com/2011/06/tour-of-the-minidsp-2x8/.

Also, you may want to just buy the plugin and try it out to be sure it will do what you want, it's only $10: http://minidsp.com/onlinestore/detail/13-audio-plug-ins/flypage/77-4x10-plug-in?sef=hcfp.

JDUBS · « **Reply #91 on:** 23 Aug 2011, 03:23 am »

Quote from: JohnR on 23 Aug 2011, 02:55 am

The miniAMP question is answered here: http://www.minidsp.com/forum/10-minidsp-for-newbies/2305-re-is-2x8-compatable-with-miniamp?limit=6&start=48#2481

Yes to your questions, if I understand what you are asking - for more info perhaps the article will help: http://www.hifizine.com/2011/06/tour-of-the-minidsp-2x8/.

Also, you may want to just buy the plugin and try it out to be sure it will do what you want, it's only $10 - http://minidsp.com/onlinestore/detail/13-audio-plug-ins/flypage/77-4x10-plug-in?sef=hcfp

Thanks on all fronts, John. Very interesting indeed. It seems that you can only pull two channels of amp output when the miniAMP is stacked on either the 2x8 or the 8x8. Having 4 channels available would have been cool....saved another component in my rack, but its not a big deal.

Good idea on dl'ing the plugin. I think I may do that.

How cool would it be to put a 2x8 + miniDIGI + miniAMP + a Linux (Voyage) based ALIX mb in a single (not that huge) box? You would have 24/96-capable streaming, DSP / elecontric crossovers, and 2 channels of amplification all together? Pretty awesome! Plus, not that expensive, although it would take some DIY'ing...

-Jim

JohnR · « **Reply #92 on:** 23 Aug 2011, 04:07 am »

What's a "Linux (Voyage) based ALIX mb"?

JDUBS · « **Reply #93 on:** 23 Aug 2011, 11:39 am »

Quote from: JohnR on 23 Aug 2011, 04:07 am

What's a "Linux (Voyage) based ALIX mb"?

One of these:

http://www.audiocircle.com/index.php?topic=62364.0

-Jim

JohnR · « **Reply #94 on:** 23 Aug 2011, 11:55 am »

Ah. Sorry

I just run the optical out from a mac mini to the miniDigi on the 2x8. I wouldn't mind a case for the 2x8/digi though.

JDUBS · « **Reply #95 on:** 24 Aug 2011, 09:47 pm »

JohnR, thanks for all the info and advice...I downloaded a plug-in and love the interface. I've decided to try out an 8x8 with miniStreamer, miniDigi, and miniAMP.

Looking forward to trying it out!

-Jim

pelliott321 · « **Reply #96 on:** 6 Sep 2011, 01:40 pm »

I heard back from DSP and that they tested my card and found it within specs.
They stated that the noise that I showed on my scope was out of the audio band and would not effect the sound.
and they are sending the unit back. I doubt that I will use it. I can not believe that the .5 volts of noise I measured does not effect the sound. What I was hearing was that the sound was very fatiguing, just not very pleasant. I doubt that I will use this as an active xover in my system.

jtwrace · « **Reply #97 on:** 6 Sep 2011, 01:42 pm »

Quote from: pelliott321 on 6 Sep 2011, 01:40 pm

I heard back from DSP and that they tested my card and found it within specs.
They stated that the noise that I showed on my scope was out of the audio band and would not effect the sound.
and they are sending the unit back. I doubt that I will use it. I can not believe that the .5 volts of noise I measured does not effect the sound. What I was hearing was that the sound was very fatiguing, just not very pleasant. I doubt that I will use this as an active xover in my system.

The good news is that A.C. has a classified section.

JohnR · « **Reply #98 on:** 6 Sep 2011, 02:06 pm »

Sounds like it can't be that hard to filter out. Maybe Davey's offer is still open.

pelliott321 · « **Reply #99 on:** 7 Sep 2011, 03:14 pm »

To me the important thing is that DSP did admit that the noise was there and it is within spec, which means all the DSP 2X8 units have this "out of audio band noise" (see I am not crazy after all)
Now the question is where is the noise high or low and how to filter it.
when I get the unit back I will do some more work on the scope. I do not have a very high freq scope. but I will see what I can do