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PostPosted: Mon Apr 18, 2022 11:02 am 

Joined: Wed Mar 30, 2022 5:29 am
Posts: 50
Hi all,

I'm in the market for a new USB/External sound card for our Dell Optiplex 9020 USFF PC. We use this as our feed to our TX.

We currently receive signal over our LAN from our Broadcast PC to our TX PC. ST 9.90 is installed on this PC. (https://www.nzpcclearance.co.nz/product ... sff-pc-i5/)

The sound quality is pretty good considering it's feeding the TX using the onboard Realtek sound card. However, I'm wondering if significant gains in terms of clarity and a more "full" sound can be had with a new sound card?

I've tried pretty much all the presets available in ST, and pretty much all of them don't seem to produce the crispness and fullness found on other local stations, so I suspect it's probably the onboard sound card.

We're only using a 1W TX, so it makes no sense to go high-end, I was thinking somewhere around US$250 (which equates to a whopping NZ$500!). Though less would be much better. I guess the spec would be 192k, ASIO ready, and it must be an external drive.

Any advice would be greatly appreciated!

Baldrick


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PostPosted: Thu Apr 21, 2022 2:08 pm 

Joined: Tue Feb 09, 2021 1:06 pm
Posts: 4
Location: Nottingham
Hi

If you can manage to find one I strongly recommend the Douk Audio PCM5012 USB XMOS DAC (https://doukaudio.com/products/douk-aud ... card-p0052)

Do not be put off by the low price or the fact it has a headphone output, this is an excellent product and works exceptionally well with ST.

If you are interested, the data sheet for the chip is here: https://www.ti.com/product/PCM5102A
On this product, the phono outputs are driven directly from the DC coupled outputs of the chip i.e. there are no DC blocking capacitors in the signal path.
At 192k the DAC response is flat within 0.05dB from DC to 85kHz which is more than adequate to faithfully carry the MPX including RDS.
I am using an AAREFF 1W exciter which I have modified to have a modulation response down to 2Hz rather than 30Hz out of the box so I have no requirement to use the tilt/RC compensation in ST.
Using a Pira P275FM FM analyser I can see that the peak modulation control is excellent and the RDS phase is bang on which is probably due to the fact that there is no post filter after the DAC in the box.
I cannot fault the sound quality too, it stands up to anything on the dial (assuming you have the right preset in ST of course!).


Hope this is helps.

Regards,

James.


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PostPosted: Sun Aug 13, 2023 9:47 am 
User avatar

Joined: Wed Sep 01, 2021 8:20 pm
Posts: 21
Location: Los Angeles, CA, USA
Quote:
Hi

If you can manage to find one I strongly recommend the Douk Audio PCM5012 USB XMOS DAC (https://doukaudio.com/products/douk-aud ... card-p0052)

Do not be put off by the low price or the fact it has a headphone output, this is an excellent product and works exceptionally well with ST.

If you are interested, the data sheet for the chip is here: https://www.ti.com/product/PCM5102A
On this product, the phono outputs are driven directly from the DC coupled outputs of the chip i.e. there are no DC blocking capacitors in the signal path.
At 192k the DAC response is flat within 0.05dB from DC to 85kHz which is more than adequate to faithfully carry the MPX including RDS.
I am using an AAREFF 1W exciter which I have modified to have a modulation response down to 2Hz rather than 30Hz out of the box so I have no requirement to use the tilt/RC compensation in ST.
Using a Pira P275FM FM analyser I can see that the peak modulation control is excellent and the RDS phase is bang on which is probably due to the fact that there is no post filter after the DAC in the box.
I cannot fault the sound quality too, it stands up to anything on the dial (assuming you have the right preset in ST of course!).


Hope this is helps.

Regards,

James.
What modifications did you do on your exciter?

_________________
NKUB-FM 100.7 The Cube
We're the station for LA's cubers!


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PostPosted: Wed Aug 23, 2023 1:34 am 

Joined: Fri Jan 21, 2022 9:51 pm
Posts: 12
Refer to my recommendation in this post:
viewtopic.php?f=5&t=12695

The ALC4042 is a capless design too, like the Douk as recommended by James. It is even way cheaper though, but the same outstanding quality for MPX!


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PostPosted: Tue Nov 21, 2023 4:31 pm 

Joined: Tue Nov 21, 2023 4:08 pm
Posts: 2
Native Instruments Audio 1
Then Use a premade RCA to BNC cable for perfect FM fed to the transmitter's COMP input.

Works beautifully for our 100KW FM, loudest and cleanest audio within 100 miles of any music genre.


Good luck


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