Autoranger for soundcards

[HpW]

Hi HpW, Please do.
-Chris

Thread about DIY talk's on RME ADI-2 Pro

There we go http://www.diyaudio.com/forums/equipment-tools/301013-diy-talks-rme-adi-2-pro.html#post4923610

Hp

 

[jan.didden]

A pair ready for shipment to the beta testers. I actually made my self-imposed deadline 'end of 2016'

Jan

 

[ergo]

Very nice!
I'll be one waiting for opportunity to order one

 

[Bob Cordell]

A pair ready for shipment to the beta testers. I actually made my self-imposed deadline 'end of 2016'

Jan

Congratulations, Jan.

I wish I could always make my self-imposed deadlines .

Cheers,
Bob

 

[anatech]

Hi Jan,
That is looking good.

-Chris

 

[jan.didden]

Status update: two complete units send out for beta-testing.
In the mean time, you can download the preliminary User Guide here to get a feel for the operation of the unit.

Comments invited!

Jan

 

[vacuphile]

It's a beauty, nice colors and cool stencil lettering!

 

[Carl_Huff]

Very nice Jan! Congrats on driving this project to completion

 

[anatech]

Hi Jan,
That is an excellent looking unit. Do you have basic specs for it yet? Stuff like maximum frequency -3 dB point, maximum input level? Stuff like that. I guess we might need the lowest frequency too.

-Chris

 

[jan.didden]

I still have to put a spec sheet together, but so far I have:

- a few Hz to 100kHz within +/-0.1dB;
- THD around -118dB (best I could measure with a Sys2722 so could be less);
- Vin max 100VRMS, gain range -40dB to +16dB in 4dB steps at also 0.1dB accuracy.
- The level display is accurate (after calibration) to better than 1%.

There's no minimum level but at +16dB for 1V out the input level is around 160mV IIRC.

Jan

 

[anatech]

Hi Jan,
Excellent specs. The sound card would be the limiting factor most likely.

-Chris

 

[jan.didden]

Yes that is the idea!

Jan

 

[DualTriode]

KickStarter Date?

Estimated KickStarter Date?

 

[BlacK_Chicken]

Any news here?

 

[jan.didden]

Two units are in beta test with a few people. I am getting some feedback with recommended changes, in particular on the data displayed.
There may also be a review in an audio journal.
I expect to start the Kickstarter start of the summer.

It has taken a bit longer than I expected but functionally it is done and works as expected.

Jan

 

[blmn]

Hi, Jan!

Very well done! Congrats!

When it will available for sale, if you were planning to sell that?

Regards,

 

[1audio]

RE output levels. There are several considerations/aspect to this. First the level to get 0dBFS is not consistent between cards. The pro cards tend to use -10 or +4. Consumer card anywhere from .5v or less (mike in) to 2V +.

The other issue is that the ADC's best performance is not at max in. Typically its -10 to -20 dBFS. I find that this is not a major limitation with the better sound cards. I use a higher resolution FFT which looks deeper into the noise. It will also permit testing with higher crest factor waveforms like IM testing. Essentially this is around 250 mV. on a 2V 0dBFS card. The same is also true of the DAC source usually.

Use the balanced to balanced-differential connection to get the best isolation from noise sources.

 

[jan.didden]

RE output levels. There are several considerations/aspect to this. First the level to get 0dBFS is not consistent between cards. The pro cards tend to use -10 or +4. Consumer card anywhere from .5v or less (mike in) to 2V +.

The other issue is that the ADC's best performance is not at max in. Typically its -10 to -20 dBFS. I find that this is not a major limitation with the better sound cards. I use a higher resolution FFT which looks deeper into the noise. It will also permit testing with higher crest factor waveforms like IM testing. Essentially this is around 250 mV. on a 2V 0dBFS card. The same is also true of the DAC source usually.

Use the balanced to balanced-differential connection to get the best isolation from noise sources.

Demian, that is good info, for some reason I have been working with 1V as sound card sweet spot. BTW you could verify your sample by inserting 1V so it ranges to 0dB, then pressing Hold so it won't switch and then check with .5 or .25V.

I will look into setting the sweet spot much lower but it might need a hardware mod. If 0.25 is the sweet spot, the range of -40dB to +16dB should probably be shifted downwards.

Another question is what such a low sweet spot would mean for the SNR.

Jan

 

[skidave]

I find the EMU-0204 sweet spot is .5V or less (input). Best SNR in this range. I have three steps to my passive divider that keeps the level between .3 and .5V. This allows testing of high power (200-400Watts) amplifiers without any issues.

Also supporting what Demian said about the output of the sound cards.

 

[davada]

Demian, that is good info, for some reason I have been working with 1V as sound card sweet spot. BTW you could verify your sample by inserting 1V so it ranges to 0dB, then pressing Hold so it won't switch and then check with .5 or .25V.

I will look into setting the sweet spot much lower but it might need a hardware mod. If 0.25 is the sweet spot, the range of -40dB to +16dB should probably be shifted downwards.

Another question is what such a low sweet spot would mean for the SNR.

Jan

Jan have you considered small plug in board. I made a filter board years ago where the tuning resistors plugged into an IC socket. You could do something similar for scaling.

Of course this won't help if you already have boards made up.