Integrated audio vs. sound card

[Alan Johnson]

In the never-ending quest to make things better, I'm wondering if switching from the integrated audio (soundMAX) on my motherboard to a PCI sound card would make a significant difference in my DRM reception. The integrated audio seems to work OK, but my max SNR is 20 to 21. I wonder if a separate sound card would yield higher SNR's. Has anyone made the switch?

Thanks,
Alan

[carknue]

Hi Alan,

I don't think, that you could improve your SNR with an PCI soundcard, becuase the limiting factor in your case is proberbly the Winradio G303.

In my former PCs, I always added a PCI soundcard, but that was just because the integrated gave no good sound quality output and they were quite noisy. I made the experience that if DRM worked with the internal sound chip, the SNR was not really improved by the PCI card. Mostly the RX is the limiting factor. With my AOR the SNR limit is somewhere around 35 dB and this was reached always by the internal or PCI card.

Because of fatal system crash last month, I had to buy a new PC. I used to receive DRM only with my notebook, because the Tower PC made a lot of EM noise above 13 MHz. I bought now a Dell XPS 210 to replace my Tower. I praid to god that this system would be able to receive DRM with the internal sound chip. And yes, it works very well. It has an Sigma Tel 7.1 chip, and a software that turns it into a soundblaster Audigy advanced. Important for me was, that it has an optical output to avoid ground loops when connecting to the hifi system. It works perfectly ot of the box without changing anything, as you can see in the screenshot.

The XPS 210 is very small, very powerful, not too loud. The only disadvantage for me is, that it has no serial com port, but it has one free PCI express slot, where I will add a serial port card.

[mitajohn]

Hi,

As Carsten said, the SNR figure depends on the receiver as well as on the antenna used and the interconnections with the pc (in your case the interconnections are minimal), to avoid ground loops and rf interference and of course on the man made electrical noise level around your place. I live in a noisy suburban environment and I use an on board soundmax (on an Intel MB) with DRT1 and Elektor receivers. In "lab" conditions the DRT1 results in an excellent SNR figure of 48 dB and by air of about 38 dB(my record is ~38.7 dB). The Elektor results at somewhat lower figures compared to DRT1. The soundmax works OK and my only problem with that one is that I cannot run 2 instances of Dream at the same time.

[Alan Johnson]

Thanks for the info. I'll save the money for a new computer.

Alan

[dadalbinder]

I had a lot of problems connected with Soundcards.

1. One type of problems, is to engage an Onboard-Soundcard. Regularily there is a lot of signals from the mainboard jumping into the Onboard-Card. Because of that, the SNR of decoding DRM is not so good.

2. Next Step is to use a separate Card to place into a slot. Generally there is a better isolation from alle frequencies of the mainboard coming in.

3. Next step in my case is to obtain an USB-Soundcard. I have on my system a Creative SB Live 5.1 Digital and now since short time a Creative SB Surround 5.1. USB with best results.

4. The results of decoding DRM by these two cards (both are installed in my machine) are nearly the same using a DRT1, Elektor-DRM-receiver, Adapted Lowe-HF150. There are differences of SNR between these receivers because of the different signal processing facitlity of the receiver. By far the DRT1 has the best performance, following the Elektor-DRM and Lowe with only a little difference to these but a big to the DRT1.

5. I use at the moment a receiver following the pages of www.elexs.de and www.B-Kainka.de. It works with an Cypress-oscillator tuned by serial-cable and working at the principle of I/Q demodulation. I use the version with the analog amplifier TL084. It has a performance for DRM near to the DRT1. Only a limited number of circuit elements, surprising. You find protocolls at www.drm-dx.de referring to IQ, CY27EE16. There are screens from DRMCalc on my computer too.

6. But this receiver works sufficiently only with the USB-Soundcard.

7. One has to look on the possible parameters of soundcard-working as Samplerate and a lot of others. At the sofware of www.Audiotester.de there is some shareware for a limited time for Wavegenerator, Analyzer and Oszi. In the last software there is a sub-menu: Audio-In-Paramters, where You can test the response of the soundcard to the programm and see, wich parameters the soundcard assists.

8. There is a Soundcard-Testing circuit by B. Kainka with a NE555 to be seen on the Internet-pages mentioned and where one is able to test the function of a soundcard especially stereo-ability, filtering by Anti-Aliasing-Filter. There are a lot of screens of different situations. But first: change and fix the suitable parameters for the card.

9. I had a lot of experience from people, who were trying DRM with several adaptions of receivers or spezialised receivers. There is a big scale from: Does not go to best experience. The soundcard itself has a certain position of quality for the whole system.

Test and have a look.

At last: Not every Onboard-card is a bad card.

Wolfgang Hartmann, 49N28, 11E00

[TobbeR]

Hi
I have tried several cards and most is just fine except the most expensive one
a M-Audio Delta AP192 which is totally useless as I see it. My setup is a BRD30 from German company NTi and the 192 with it's low noise worked very well for AM or SSB listening. When I tried it on DRM with Dream it lost sync every 2-4 minutes, looks like the card adjusts it's internal frequency now and then. I had a Turtle Beach Santa Cruz in the box, also very low noise and it worked very good, best SNR from Sines sofar around 35-36. The internal SoundMax card is ok but since I had the Santa Cruz I have not used it a lot. On another box with a ASUS mobo and Linux I had to use the internal REALTEK ALC650E, no complains at all.
Low noise on the soundcard looks nice but on the bands used for DRM transmissions the natural ,and man-made, noise is high anyway so maybe it's not that important.
Regards
TobbeR

[richard]

Like most people I don't think the sound card is normally the major noise source. There will probably be more noise coming from the rest of the PC and power supply, especially through the common ground.

For me a few turns of audio cable on a ferrite ring did not help reduce the interference a lot. Recently though I bought some miniature shielded audio cable, which was only 2mm in diameter. With this I was able to wind about 30 turns of it onto the ferrite ring. So far this is the best way I have found to provide isolation from the PC. Unfortunately there is always going to be some RF leakage across a single choke, especially when using a switched supply. The next improvement is probably a loop or balanced antenna system, which is another topic.

Richard