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Old 18th March 2013, 07:47 PM   #671
paalj is offline paalj  Norway
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Quote:
Originally Posted by paalj View Post
Guess I have to wait for "Decimation" or similar

best,
Paal
Hi Nick,
Just found that Acourate does the decimation. up to 15x...

best,
Paal
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Old 18th March 2013, 08:01 PM   #672
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Originally Posted by rubofdagreen View Post
I have been staring at switches for a long time at Digikey, and it is only slightly less grueling then reading this thread from start to finish. I would have swore this was several hundred pages long. Paid for my board today and was hoping for some input on parts. Switches, unlit or lighted? Power supply, case, etc. Any help would be appreciated.
I just some really cheap ones, but now I know this setup is a keeper, I'll be looking for a nicer action keypad, perhaps a bigger display too.

I like the way there are no LED's on when playing analogue too
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Old 18th March 2013, 08:34 PM   #673
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Hi,

a free software to generate any kind of FIR filter,EQ.
rePhase | Free Audio & Video software downloads at SourceForge.net

you can have a look to the stop band ripple,according to Fs and taps number

Click the image to open in full size.

Last edited by thierry38efd; 18th March 2013 at 08:43 PM.
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Old 19th March 2013, 05:40 AM   #674
Shaun is offline Shaun  South Africa
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Originally Posted by Speedysteve7 View Post
I like the way there are no LED's on when playing analogue too
There is actually a quite useful LED, I found last night: AD CLIP. Correct that it should not light up during normal play.
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Old 19th March 2013, 06:29 AM   #675
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Originally Posted by Shaun View Post
There is actually a quite useful LED, I found last night: AD CLIP. Correct that it should not light up during normal play.
Yes I found that One too.
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Old 19th March 2013, 10:35 AM   #676
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After PM with chaparK here is a relevant question that we thought merits further discussion in the thread:

Can the analog output gain be set per channel?

The answer is currently No.

To see why this might be of use consider a 3-way loudspeaker with different element sensitivities. From a digital standpoint it's desirable to have filters of roughly unity gain but this would be impossible if there is say 10dB difference in sensitivity between elements.

Another case could be that we wish to use an existing power amplifier that has a different voltage gain for one channel.

In my specific case the problem is made worse by the combination of these two factors.
  • My bass amplifier is Class-D with voltage gain 26dB. The other channels are voltage gain 31dB.
  • The crossovers need to be roughly 10dB hotter for the bass channel.

So it seems I would need to increase the analog bass output from the board roughly 15dB to get unity gain digital filters.

Comments?

/K
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Old 19th March 2013, 10:44 AM   #677
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by Speedysteve7 View Post
What sort of core load is normal. I am at 44 and 38% on 96KHz and doing 8 channels.
Regarding DSP load, any is good as long as it's below 100%.
You must make sure you don't go above 100% on any core. It's a drama otherwise.

Indeed, if you go above 100% on any core, the DSP will drop one sample and this will translate into halving the sampling frequency.

Now, what happens is that all the DSP parameters have been computed for that sampling frequency that you have selected when you created the Setup file. So if the effective sampling frequency is halved due to DSP overload, all these parameters will be wrong and the output will not be what you would expect.

There's one unused hardware led. I was thinking of using it to signal when the load goes beyond 100% on any core. How about that?

On the other hand, don't think that the DSP is happier when you lower the load. So as long as you are under 100%, any load is fine.

Quote:
I've ordered a IR sensor, and have an All-In-One remote that should do JVC and NEC codes.
Cool! Let me know how it goes. I've a tested dozen of remote controllers, collecting some here and there - but more test is always better

Quote:
Originally Posted by rubofdagreen View Post
...was hoping for some input on parts. Switches, unlit or lighted? Power supply, case, etc. Any help would be appreciated.
For switches I'd recommend unlit ones, of tactile type.

Quote:
Originally Posted by paalj View Post
Hi Nick,
Just found that Acourate does the decimation. up to 15x...
I'm actually looking at how we could add decimation. I think we'll make it.

Quote:
Originally Posted by Shaun View Post
There is actually a quite useful LED, I found last night: AD CLIP. Correct that it should not light up during normal play.
So the AD Clip led is a status reported by the ADC itself. If the input level is too high, this is detected by the ADC and communicated to the micro and the control app. The only thing you can do to cure it is to lower the level of your analogue input.

All the other Clip leds are statuses reported by the DSPs. If there's too much gain in one part of the processing, the DSP will truncate the data word and set a flag. The cure here is to check your gain structure.

There are 3 processing clipping leds:
- Bass/Treble led: add headroom in the Bass/Treble dialogue
- Input processing led: Check your gain structure on the Input Processing tab.
- Output processing clip: Check your gain structure on the Channel processing tab.

(Note: the hardware leds will not tell you which channel or input precisely is clipping. But the control application will. On the monitor tab, each input has a dedicated software clip led, and each channel has the top segment in the VU-meter which acts as a clipping status).
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Old 19th March 2013, 10:49 AM   #678
hajj is offline hajj  Lebanon
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In most cases, the lower sensitivity drivers are the ones in charge of the lower octaves, at these frequencies the human ear is much less sensitive to distortion (within limits of course).
In this case, a simple and straightforward line level voltage preamp (like Elliot sound's) can easily be used to amplify the relatively low output signal.
I think that ultimately, there are always compromises to be made, and this one is an easy one to make.
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Old 19th March 2013, 10:56 AM   #679
JLOP is offline JLOP  France
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Quote:
Originally Posted by kazam View Post
After PM with chaparK here is a relevant question that we thought merits further discussion in the thread:

Can the analog output gain be set per channel?

The answer is currently No.

...
Comments?

/K

For the very good reasons you have detailed, I think it is definetely a must. Otherwise, one may need to add (expensive) pots/Lpads just before the loudspeakers, while we are trying to go digital as much as possible.
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Old 19th March 2013, 10:56 AM   #680
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by thierry38efd View Post
a free software to generate any kind of FIR filter,EQ.
rePhase | Free Audio & Video software downloads at SourceForge.net
Thanks Thierry I'll check this app soon.

Quote:
Originally Posted by kazam View Post
After PM with chaparK here is a relevant question that we thought merits further discussion in the thread:

Can the analog output gain be set per channel?

The answer is currently No.

To see why this might be of use consider a 3-way loudspeaker with different element sensitivities. From a digital standpoint it's desirable to have filters of roughly unity gain but this would be impossible if there is say 10dB difference in sensitivity between elements.

Another case could be that we wish to use an existing power amplifier that has a different voltage gain for one channel.

In my specific case the problem is made worse by the combination of these two factors.
  • My bass amplifier is Class-D with voltage gain 26dB. The other channels are voltage gain 31dB.
  • The crossovers need to be roughly 10dB hotter for the bass channel.

So it seems I would need to increase the analog bass output from the board roughly 15dB to get unity gain digital filters.

Comments?

/K
Indeed we had a brief chat with Kazam and I thought we could discuss this topic here as this would be a great feature.

Not just specifically for Kazam's application, but also to provide more flexibility in the gain structure.

Currently, all the gains that you set in the processing tabs are DSP gains. I said to Kazam that it would be easy to add independent analogue gain everywhere in the system - except on the GUI (i.e. the pc app interface). So it's a bit tricky in the GUI because I must also support boards without analogue volume...

Right now, you can adjust globally the output level in the Board Configuration dialogue.
Would it be alright to replace this global adjustment with individual controls for each channel? Any thoughts?
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