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Old 18th January 2014, 07:02 AM   #41
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by Shinja View Post
I am planning to make 3stage cascaded twin-T notch filter...
Hi,

Have you completed the design? Will it be variable/selectable frequency?

-RM
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Old 29th January 2014, 08:07 PM   #42
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by 1audio View Post
The Benchmark would be good but its $1800 and not optimized for measurements. I will do the part swap on the Emu to see what I get. I think an analog upgrade board for the Juli may be the best option for the amateur. I will have demo boards for the ESS ADC soon. I'll see what the best option is.

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Did the ESS demo boards arrive and have you tested with them, yet?


Thx-RNMarsh
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Old 29th January 2014, 09:05 PM   #43
1audio is offline 1audio  United States
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No ESS stuff yet. (I need to check, they go my Fedex for it a week ago).

The emu 1212 is a dead end for this stuff. I going to sell my emu collection. I'm going to invest time into a new card for the ESI Juli@. That has the highest potential for good results.
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Old 1st February 2014, 02:03 PM   #44
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Someone else on another message board told me about Ross Martin:
More Ear Gear

He makes a PCM4222 ADC which would be good for measurement purposes. There's also a USB to SPDIF interface in another box. These are basically hand made items, but relatively inexpensive in my opinion for what you get. I have no relation to the business, but I am planning on getting their gear.

Just thought I'd share.
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Old 13th February 2014, 09:07 PM   #45
_Wim_ is offline _Wim_  Belgium
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Hi,

Just to inform you, you results are very comparable with mine (I also have a "higher 3rd" with the EMU1212 pcie).

As to working with the card, I agree the PatchMix Dsp takes some getting used to, but it have some usefull features. Some examples:

- you can add een fx to simulate a loudspeaker with reflections. Usefull to play around with software measurement packages with actually making noise...
- with asio you can work work completely in software loopback. Usefull to test some DSP software applications
- you have many asio channels, with allow you to "route" audio from one application to another. For example you can measure with ARTA and with the signal generated by ARTA on a seperate scope software.

Attached in the zip file are some configs (sessions) I use reguarly. You can load these directly in patchmix Dsp.
Attached Images
File Type: png distorsion asio 44.1K.png (82.2 KB, 208 views)
Attached Files
File Type: zip Emu1212m.zip (12.4 KB, 11 views)
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Old 15th February 2014, 07:10 AM   #46
_Wim_ is offline _Wim_  Belgium
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I just thought of another example that some might find useful: monitoring the distortion residuals

You can do this the following way:
  • send your test signal to the physical output (Asio 1-2) from you measurement program (for example 250 Hz and 8 Khz sine for IMD testing)
  • loop this output to the DUT, and loop the ouput from the DUT back to the physical input of the soundcard (IO Card In L/R) Normally this signal is then used to analyse in the measurement software. Instead of doing this, we first send this to another ASIO channel (ASIO 3/4 => linked to VST Host)
  • make a VST Host application(http://www.hermannseib.com/english/vsthost.htm) with the following components:
  • the convolver VST can be loaded with an impulse made in Rephase (http://sourceforge.net/projects/rephase/).With Rephase you can make a deep noth filter with linear phase (or minimum phase) on 250 Hz and 8Khz. This will filter the test signal out, and leave the residual over for monitoring)
  • The output from the VST Host application is send back to your measurement software (ASIO 1/2)
The first time you set this up, it takes some work. But VST Host can load up to 128 "performances" (setups), and for the EMU card you can load and save sessions for every test setup. So to repeat a measurement, you only need to load the correct performance in VST host, and load the correct session in you sound card...

When using an audio measurement pc like this, the possibilities are almost endless. The sound card has up to 16 ASIO channels in and out, and in VST host you can make a lot of different configs (there are many free VST plugins available on the web: scope, spectrum, filters, delays, echo...)
And while some find the distorsion “high” of a sound card like this, there are not many hardware audio analysers with specs a good of this (and none that are affordable for DIY…)
Attached Images
File Type: png IMD 250Hz 8K.png (81.6 KB, 191 views)
File Type: png VST Host settings.png (261.7 KB, 191 views)
File Type: png noth filter rephase.png (99.2 KB, 186 views)
File Type: png IMD 250Hz 8K rediduals only.png (24.4 KB, 184 views)
Attached Files
File Type: zip Rephase_notch250Hz8000Hz.zip (1.0 KB, 6 views)
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Old 16th February 2014, 06:51 AM   #47
1audio is offline 1audio  United States
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Thanks for your efforts. it got me back to playing with the card. I set up a fresh install of Win XP on an SSD and tried again. I am getting better results, not as good as the demo board but I suspect the chip is running at 24 MHz not 12 MHz.

The ADC is definitely better than the DAC. Under the right conditions with an external source I can get all the harmonics below -110 and the third is lower than the second. The high third is an artifact of the DAC.

Even with this clean install I still get an occasional lock up (machine completely stops cold, not even a blue screen). With the SSD the reboot is more like 15 seconds instead of the 2 minutes with the old install.

I'll download and try your patchmix setups. They should help me understand the system.

You are running at 44.1 and using ARTA with ASIO. I tried that at both 192 and 48 and had some problems crash with both. Also using the windows sound engine.

Which version of the driver are you using? Anything else special I can look for (indexing is already off).
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Old 16th February 2014, 12:50 PM   #48
_Wim_ is offline _Wim_  Belgium
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Hi,

I have attached the EMU driver versions I am using. The card is installed in a Dell Vostro 460 pc (I5-processor) running on Win 7 Pro 32-bit. No SSD (yet)

I specifically chosen 32-bit, because I have had bad luck with 64-bit OS in the past (mostly for industrial communication use, but maybe for audio drivers, it is also not ideal…)

As to the 44.1Khz sample rate, this was just an example. I use every possible sample rate, depending on the application and software used (see for example attached summary made with RMMA) or the result when running a 70K tone with 192kHz sampling rate in loopback (with linear averaging in ARTA)
Please note, it is not like I do not have any issues with the EMU drivers:
  • When using ASIO, I sometimes have no signal. Most of the times this is resolved by changing the sampling rate (loading different sessions in PatchMix), and switching back. I do not consider this a big issue, as it is immediately apparent
  • When using WDM, I sometimes have additional distorsion. This I find really annoying, as sometimes is it not immediately clear what is happening, and you could make a false conclusion about the DUT
  • Very occasionally ( approx. 3 times in 2 year use), I have had a BSOD. Off course, I cannot say for sure this is related to EMU, because many other software packages are running at the same time

As to understanding patchmix DSP, I is really quite simple for what is typically needed in our case (but it took me quite a while to figure it out that it was easy…). You basically only need the area in the red rectangle, all the rest we do not need for our typical purposes.

In short: in the patchmix you can add strips (in attached example I included six strips). Each strip corresponds to an INPUT of the DSP/soundcard (this can be a physical input or an ASIO input). The VERY confusing part is that EMU gives these strips the name ASIO OUT X/X, because in their thinking, it is the output from another music application like an effect processor) Once you figure out this is also an input just like IO Card in L/R, all becomes clear!

For each strip, you can add INSERTS in the zone marked by the blue rectangle. These inserts can be one of the following:
  • Peak meter (I always insert this first to see where I have a signal, and how high it is)
  • A trimpot (adjustable gain)
  • An Fx for the DSP (a filter, a special effect, a delay…)
  • A SEND where the input is send to an ouput (for example an ASIO output or a physical output)
This means a minimum configuration consists of the following (I attached this session):
  • An “ASIO OUT 1/2” strip with a SEND-insert to the physical IO Card output L+R
  • An “IO Card In L/R” strip with a SEND-insert to ASIO channels 1/2
As an "advanced" example, I attached a session were you have “virtual ASIO cables” that allow you to send audio from one application to another application.

Tips:
  • a strip can have many SEND insert, so the input from the DUT can be send to multiple analyser software’s at the same time
  • you can send to ASIO and Wave (WDM) at the same time, so this allows you to use both type of applications together
  • Combining these functionalities with software like VST Host (see previous post) and Virtual Audio Cable (or free alternatives like VB Cable) give you almost unlimited routing functionality (just like you have linked BNC cables with T-pieces from one hardware equipment to another).
All the above is the reason why I think people should consider working with a professional sound card instead of dedicated hardware. I agree it is less plug and play, but one you discover the flexibility for an audio measurement setup, there is no going back...
Attached Images
File Type: png Versions.png (370.8 KB, 78 views)
File Type: png Patchmix.png (435.7 KB, 62 views)
File Type: png Summary Sampling Rates.png (21.3 KB, 58 views)
File Type: png distorsion 192kHz with 70K sine.png (44.7 KB, 66 views)
Attached Files
File Type: zip ASIO Virutal Cable 44.1-48 kHz.zip (958 Bytes, 8 views)
File Type: zip ASIO minimum configuration 44.1kHz - 48kHz.zip (937 Bytes, 9 views)
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Old 16th February 2014, 08:46 PM   #49
1audio is offline 1audio  United States
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Thanks for the details. After some fiddling I'm getting much better results. I swapped the opamps on the board to LME49880 dual Jfet opamps and the distortion is significantly improved (-120 dB on the harmonics). But it still locks up too often to keep it in the system. I may have a bad board.

The system is really stable except when the EMU1212 is in it. If you were on this side of the pond I'd send the cards to you to try. The opamp upgrade is worth the effort if you are equipped to make it.
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Old 17th February 2014, 04:41 AM   #50
1audio is offline 1audio  United States
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Tried again from the beginning. Removed the card and driver made sure the system is stable, then reinstall from the original disk. That seemed to do the trick. The board seems stable now. Even after upgrading the driver. So install from the disk first.

Sent from my Nexus 7 using Tapatalk
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