New miniDSP 2x8 / 4x10 card

KenTripp · « **Reply #60 on:** 21 Jul 2011, 04:15 am »

Quote from: JohnR on 30 Jun 2011, 01:48 am

I usually use the linkwitz-riley crossover, except at low frequencies where I use whatever gives the best response.

JohnR,

In your "Refining a 4-way open-baffle speaker with the miniDSP 2×4" you played around with first order filters to take advantage of their better transient response. Have you pursued this with the 2x8 board?

JohnR · « **Reply #61 on:** 23 Jul 2011, 05:00 am »

Quote from: KenTripp on 21 Jul 2011, 04:15 am

JohnR,

In your "Refining a 4-way open-baffle speaker with the miniDSP 2×4" you played around with first order filters to take advantage of their better transient response. Have you pursued this with the 2x8 board?

Hi Ken, no, I didn't copy over the settings for the first-order crossover, as overall I preferred the high order crossover, at least with my drivers and the crossover frequencies I was using.

pelliott321 · « **Reply #62 on:** 3 Aug 2011, 03:42 pm »

I got back my 2X8 from China. No word what was wrong but its is now powering up and recognized but the laptop. I have loaded the config. so now I need to set it all up and take a listen. give me through the weekend and I should have a report

JohnR · « **Reply #63 on:** 4 Aug 2011, 02:25 am »

Oh OK, cool. Stick with the beta0 plugin, I'd not use the beta1 plugin at this point.

pelliott321 · « **Reply #64 on:** 4 Aug 2011, 08:09 pm »

this my set up for Maggy IIIa's
no eq or delay yet until I listen for awhi

just left side shown

le

pelliott321 · « **Reply #65 on:** 7 Aug 2011, 02:08 pm »

Well I am up and running
here is first trueRTA pink noise plot with the config shown previously

so I have some work to do in the eqing side
but its a start
I am thinking its sounding pretty good

JohnR · « **Reply #66 on:** 7 Aug 2011, 02:10 pm »

Cool, that didn't take you long

In room response is a funny thing.

Davey · « **Reply #67 on:** 7 Aug 2011, 02:40 pm »

What is your target?

You're going to try and flatten that and remove the tilt?

Remove all the little "wiggles" in response?

Dave.

Tyson · « **Reply #68 on:** 7 Aug 2011, 06:35 pm »

Raise the entire midrange a few db, and bring up the tweeter to match. Then just a small boost at 400hz, one at 5khz, and one at 90hz and you'll have very flat in-room response! Now, whether or not flat in-room response sounds best to you is another story

Personally I listened "flat" to my speakers a long time, but in the end I preferred a "house curve" that kept the bass and mids flat, but lowered the tweeters slightly.

Of course, that's the beauty of active - you now have absolute control to tailor the sound to however YOU like it, and you can make the changes on the fly. Awesome stuff, and can be slightly addictive

pelliott321 · « **Reply #69 on:** 8 Aug 2011, 03:03 pm »

yes, tonight I will try to lower the bass a bit. With the passive xover I had real problems in the 40 to 60hz range which is now being controlled very well. Gone are the peaks and suckouts. I will lower the subs level a little. and shelve up the mids. 3db. Its just too cool to be able to try all the different possibilities and hear them in real time. I save the configs each time I make a big change and number them so I can always go back a step or too if needed.
I have shelved the highs up some, but I believe the amp I have for the ribbon just will not work. Its a tube amp and the impedance of the ribbon is just too low for it(even with a 1 ohm resistor in series).
I have another amp to try. I will keep the 60watt tube amp for the mids, It's doing just fine.
Once I get things reasonably flat I, may try to eq out some of the peaks. The suck outs are more likely to be room effects I do not think there is much one can do about that.
One interesting note, while configuring the slopes and eq I notice a funny warbling mid freq noise in the background, very low but noticeable from the listening point. It did not change with volume. After checking all connections and playing with the grounds, moving, replacing interconnects, I still could not get rid of this nose. Then I happen to notice the noise varied a little as I was moving the sliders on the eq in the software. Ah ha! I saved the present config and un-plugged the USB cable and the noise disappeared.
Now I have just a whisper of noise that can only be heard with ear right at the panel. i do not think this is anymore or less from what I had when I was in passive mode. I think the miniDSp is very quiet. It's not in a chassis yet just mounted on a board with some feet.
I am wondering what the break in period is for the audio section, and may some better coupling caps on the output but that is a ways down the line.

pelliott321 · « **Reply #70 on:** 8 Aug 2011, 10:15 pm »

a little better

remember this is pink noise generated by trueRTA so its jumping aroung alot I need do the sweep thing and average a bunch but need to learn how to do this
What is great is I can work on an eq and watch and listen what is changing. Its very obvious when listening to pink noise. just to cool

JohnR · « **Reply #71 on:** 9 Aug 2011, 12:06 pm »

I think you'll find sweep measurements to be much more manageable and useful.

pelliott321 · « **Reply #72 on:** 9 Aug 2011, 03:25 pm »

I am not hearing a vast improvement over the previous incarnation of bi-amping and passive xover..
Its sounding good. But I am wondering if I am hearing the not burned in caps on the DSP.

JohnR · « **Reply #73 on:** 9 Aug 2011, 03:30 pm »

Caps is not something I would worry too much about. Focus on getting (good) measurements on-axis and off-axis, understanding them, and implementing the DSP to suit. I would be most interested to follow your progress.

pelliott321 · « **Reply #74 on:** 11 Aug 2011, 01:05 pm »

I am beginning to understand what I am hearing. There still may be a problem with my 2X8
My sub amp has output watt meters. Two ranges. 0-10watts and 0-200watts.
With my system set up passively I use a Marchand electronic xover for the subs. With the system idling the output meter set to 0-10watt range all is quite zero watts out.
When I use the 2X8 sub channel I get a straight 6 watt unwavering signal. I cannot hear anything but its there. This made me curious. So I put the 2X8 on the bench fed it pink noise and checked each channel for out put All there.
When I connected a signal generator and checked each channel, swept the range and output was where it should be based on the xover points that was set in the software. But and this is a big but there was noise (like white noise on all channels below the audio signal. I am going to try to scope it this weekend. But the noise was quite prevalent.

Davey · « **Reply #75 on:** 12 Aug 2011, 01:55 am »

I'm not sure about the 2x8 unit, but my 2x4 unit has a noise floor below -110dbV across the full audio band. Check out the spectrum plot in this posting on the miniDSP forum:

http://www.minidsp.com/forum/9-hardware-support/1743-tapering-the-volume-control?limit=6&start=18#3193

Dave.

pelliott321 · « **Reply #76 on:** 14 Aug 2011, 01:58 pm »

Well I put my system back to biamp and passive xover amd it sounds so much better.
I must have a bad 2X8 so I requested to send it back.

JohnR · « **Reply #77 on:** 14 Aug 2011, 11:27 pm »

Oh. Too bad it didn't work out for you. I'm selling my CD player and DAC now, don't need them any more.

pelliott321 · « **Reply #78 on:** 15 Aug 2011, 06:43 pm »

they refused to take it back so in the trash it goes

jtwrace · « **Reply #79 on:** 15 Aug 2011, 06:46 pm »

Quote from: pelliott321 on 15 Aug 2011, 06:43 pm

they refused to take it back so in the trash it goes

Is it really broken? If not, I might be interested.