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Old 12th February 2010, 04:41 AM   #31
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Interesting product.

Why don't you support 44.1? It is the most obvious SR which IMO should be supported to stay away from SRC.

Is it possible to run the board without PC , once it is configured? Does it keep the configuration also after power-down/up?

When do you plan to come up with 48db slopes?

Any specs SNR/Jitter?

How about Linux support? Would at least the standard USB driver work for playback? (configuration could be done under Windows - in the beginning as a workaround)

How about power consumption?


THX a lot.

Last edited by soundcheck; 12th February 2010 at 04:55 AM.
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Old 12th February 2010, 07:03 AM   #32
minidsp is offline minidsp  Hong Kong
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Hello Soundcheck,

Let me try to answer your questions, some which could be answered by having a look at our FAQ's.

Quote:
Why don't you support 44.1? It is the most obvious SR which IMO should be supported to stay away from SRC.
Sampling rate of 44.1 is indeed typical for digital CD audio sources, but not so typical when it comes to DSP units. (48/96/192 being more typical). We do plan to release plug-ins allowing each of these sampling rate (inc 44.1khz), but just haven't had the time to get to it yet. Right now focus for the past few months has been building a hardware and plug-in portfolio. Adding different SR versions can be done from there.

Quote:
Is it possible to run the board without PC , once it is configured? Does it keep the configuration also after power-down/up?
Yes to both answers, please have a look at our FAQ's for more info.

Quote:
When do you plan to come up with 48db slopes?
No date as we don't want to make anybody feel we ought to release a plug-in even if it hasn't been tested to our expectations. It will come out but requires quite some redesign from the current firmware. We're so far busy with new hardware cards and other features our miniDSP community members asked for, so this feature may have to wait for maybe few weeks.

Quote:
Any specs SNR/Jitter?
Our tests show >98/99dB for SNR. We say > because we always de-rate our measurements.

Quote:
How about Linux support? Would at least the standard USB driver work for playback? (configuration could be done under Windows - in the beginning as a workaround)
Errh, wasn't the exact same question just asked right below??? Do i need to say it again? :-) Also bear in mind that the USB is for control only. miniDSP kits are not a USB audio streaming device, so playback isn't going to happen.


Quote:
How about power consumption?
Boards run about 250mA @5V so well within the specs of USB self powered. Please check spec sheet and our website for more information.

Hope this information helps,
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Old 12th February 2010, 08:35 AM   #33
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THX for the feedback.

Sorry - I missed your FAQ.


I think 44.1khz and 48db slopes are pretty basic features for a DSP crossover.
I'll for sure wait until these are supported.

No idea if that has been asked before:

What's the maximum delay I can apply per channel?
What's the overall latency? How big is the input buffer?

So - now I'll read your FAQ.

Cheers
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Old 12th February 2010, 11:06 AM   #34
brubeck is offline brubeck  Netherlands
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I support Soundcheck with the 44.1 khz question. I would like to use the minidsp device between the SB and DAC (with I2S in/out) @ plain 44.1khz

Is it possible to control L/R balance with software or hardware? If no can a plugin be made for that?

thx

Last edited by brubeck; 12th February 2010 at 11:12 AM.
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Old 12th February 2010, 12:05 PM   #35
domtw is offline domtw  France
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I also think 44.1KHz is quite needed to be compatible with most format's sample rate...
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Old 16th February 2010, 04:10 AM   #36
minidsp is offline minidsp  Hong Kong
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Let me try to clarify a couple of things about Sampling Rate.

Quote:
I think 44.1khz and 48db slopes are pretty basic features for a DSP crossover.
What would be the case where you would need 44.1kHz input?
- If you decide to input I2S to the miniDSP kit as a Master. So the question is: Which device would you use to input I2S @ 44.1kHz? Most likely, you'll get 44.1kHz if you use a digital source like an SPDIF source from a cd player. If that's the case, then use our SPDIF I/O card with Sample Rate Converter embedded to get the I2S to 48khz. As for putting the miniDSP in between 2 digital devices (I2S in&out), ask yourself which one will be the master/slave first.

This being said, we'll one day release the 44.1kHz, but I just wanted to clarify what sounded like a mis-understanding about SR and that the fact that it doesn't support it currently may be a non issue depending on how you're using the board.

Quote:
What's the maximum delay I can apply per channel?
Please have a look at our plug-in spec sheets since it depends on each DSP configuration. Most of them support 7.5ms/ch.

Quote:
What's the overall latency?
We did some measurements for each plug-in but don't have them in front of me as our engineering staff is on Chinese New Year Break. I remember being in the order of 1.5ms or so, but can't be definitive. will look into it and get back to u.
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Old 16th February 2010, 08:13 AM   #37
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Quote:
Originally Posted by minidsp View Post
What would be the case where you would need 44.1kHz input?
98% of music data is 44.1.

Upsampling of 44.1 to x*48 should be avoided in any case. Your sound quality will drop.
Not only that the filtering done by your DSP will deteriorate the sound ( which might be an acceptable compromise in comparison to a HW crossover), you'll also face losses
due to resampling. That's IMO too much.

Serious audio equipment should support native sample rates.

I do understand that going the x*48khz route is the more easy way for you guys at the current stage. I am just saying that many people - including me - won't buy the board exactly due to that reason.

And again 48db slopes are also a must. Even a Behringer DCX2496 at 200$ can do that and a lot more. The Behringer I'd consider a kind of Benchmark for you guys.

Please consider this as constructive feedback. There are not very many use cases for your board. Using a PC as DSP (at 64bit!) would be by far more efficient in most cases. With a PC you can even run a convolution engine beside the crossover.
Your DSP comes in if you want to go active with a Squeezebox or a CDP, where just one I2S channel is available.

If you can hook up your board against a master clock, you might be able to use it also as reclocker of the I2S stream. In this case the Jitter performance of your device becomes
pretty relevant. The least one would expect is that your device runs at x*MCLK to avoid interferences with the signal.

Cheers

Last edited by soundcheck; 16th February 2010 at 08:16 AM.
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Old 16th February 2010, 08:35 AM   #38
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Quote:
Originally Posted by soundcheck View Post
And again 48db slopes are also a must. Even a Behringer DCX2496 at 200$ can do that and a lot more. The Behringer I'd consider a kind of Benchmark for you guys.
In terms of functionality yes... it leaves a lot to be desired in sound quality -- at least the one i tried.

BTW, price is closer to $300.

dave
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Old 16th February 2010, 08:43 AM   #39
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Quote:
Originally Posted by soundcheck View Post

Upsampling of 44.1 to x*48 should be avoided in any case. Your sound quality will drop.
Agreed...
To add to what you said, from this post in another thread.

Quote:
I am familiar with the arguments. I have been listening again and again to upsampling. I have helped design commercial CD-Players that include (selectable) upsampling. I find that ususally the sound is better without.

Here is why:

1) Basic Information Theory - there is no way to add real information, only distortion. ANY ASRC must add "misinformation". So why would I want to reduce and distort the actual information from my CD/DVD etc?

2) Filter Quality - as a rule, the digital filter in the ASRC becomes dominant in the system in which it works. This means even if the DAC's have more advanced digital filters that provide better sound quality their internal filters will be downgraded to what is in the ASRC.

For example, if you tested all different DAC"s with the ASRC in place I would expect many of the really significant sonic differences to be ereased.

3) Jitter - ASRC's cannot remove jitter, they can only translate it from one domain into another. How this effects audibility is debatable, but given that it is relatively easy to solve the issue of jitter, why use ASRC's?
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Old 16th February 2010, 09:02 AM   #40
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Quote:
Originally Posted by planet10 View Post
In terms of functionality yes... it leaves a lot to be desired in sound quality -- at least the one i tried.
dave
I guess you are aware of the DCX tweaking threads over here at DIY-A. With some easy and low budget mods it'll play in a different league.

Quote:
Originally Posted by planet10 View Post
BTW, price is closer to $300.

dave
Agreed. Price is 200€ over here ( I got mine at 100€ on Ebay.)
Anyhow - we shouldn't forget that DACs, PS is all included. I still consider the DCX as
benchmark (price-features-performance) for the miniDSP for now.
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