Simple/cheap DAC?

Znyper · 10th December 2007, 09:53 PM

Hi guys,

I am looking for a simple (and hopefully cheap) solution for some experimenting on a Dreambox. For those of you who don't know; it's a digital TV reciever box.

The built-in DAC is really not that great, so I thought I'd give it a boost using an external DAC before meeting the amp.

AFAIK, the box provides an AC-3 signal using an optical S/PDIF connector. And I only need a 2-channel output. I don't mind soldering this DAC into the amp box.

Any tips on products?

dantwomey · 10th December 2007, 11:41 PM

What is your budget?

Regards,
Dan

Znyper · 11th December 2007, 08:31 AM

Quote:

Originally posted by dantwomey
What is your budget?

As small as possible. I have no clue about prices in this line of products...

dantwomey · 11th December 2007, 01:14 PM

Although I'm replacing it in the near future I love my TDA1543 NOS which cost about $350USD.

Regards,
Dan

rfbrw · 11th December 2007, 02:35 PM

AC-3 complicates matters. It would have to be decoded first.

Znyper · 11th December 2007, 06:10 PM

Quote:

Originally posted by dantwomey
Although I'm replacing it in the near future I love my TDA1543 NOS which cost about $350USD.

Thanks for the tip, but that feels like WAY over budget..

Quote:

Originally posted by rfbrw
AC-3 complicates matters. It would have to be decoded first.

And then I'd have to pay for licencing or something...

Gaah, maybe I'd just scrap this.. I'll have a peek under the hood on the DreamBox, to see if I can just enhance the current DAC.

jkeny · 13th January 2008, 01:55 AM

Hey Znyper,
Don't give up on this so quickly - I have a dreambox (500C) also & have thought along the same lines as you. Good to find somebody else here.

I started a thread about this but it took off in another direction SqueezBox substitute

Maybe we could combine our ideas & come up with something better sounding.

I opened up the box and found a PCM1725 delta-sigma DAC which can take either normal or I2S input signals & voltage outputs. It accepts sampling frequencies 16KHz to 96KHz & operates off 5V supply. http://www.google.com/url?sa=t&ct=re...7sk7bRx4_C83Kw

Perhaps inmates could suggest a substitute with better sonics or we could improve existing output circuit. I've been meaning to look at this anyway as the sound output is pretty low & I believe this could be improved. One immediate improvement would be changing the output caps the signal passes through for something better.

Let me know what you think!

jkeny · 13th January 2008, 02:30 AM

Another improvement would be to change the op-amp circuit that signal goes through - maybe a better op-amp & surrounding circuitry.

Of course we could just take the spdif out signal & feed it into an external DAC & then an amplifier!

dj_oatmeal · 15th January 2008, 02:40 AM

I don't know if it can be done but the price is right. I would look into the Playstation as Cd player thread and see if is possible to feed the DAC on the Playstation from an external device and get it to output. You can get them in the US for about $20-$30 fairly easily. This same concept may be in my future as I have an SMC SMCWAA-G on the way from ebay (it is similar to the Dreambox/Squeezbox).

jkeny · 15th January 2008, 08:52 AM

Thanks dj,
First though, I think it's possible to improve the Dreambox internals before going to an external DAC

I'm hoping znyper and/or somebody else with a dreambox can collaborate on these improvements!

10th December 2007, 09:53 PM	#1
Znyper diyAudio Member Join Date: Nov 2007	Simple/cheap DAC? Hi guys, I am looking for a simple (and hopefully cheap) solution for some experimenting on a Dreambox. For those of you who don't know; it's a digital TV reciever box. The built-in DAC is really not that great, so I thought I'd give it a boost using an external DAC before meeting the amp. AFAIK, the box provides an AC-3 signal using an optical S/PDIF connector. And I only need a 2-channel output. I don't mind soldering this DAC into the amp box. Any tips on products?

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10th December 2007, 11:41 PM	#2
dantwomey diyAudio Member Join Date: Feb 2002 Location: Canada	What is your budget? Regards, Dan

11th December 2007, 01:14 PM	#4
dantwomey diyAudio Member Join Date: Feb 2002 Location: Canada	Although I'm replacing it in the near future I love my TDA1543 NOS which cost about $350USD. Regards, Dan

11th December 2007, 02:35 PM	#5
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	AC-3 complicates matters. It would have to be decoded first.

13th January 2008, 01:55 AM	#7
jkeny Banned Join Date: Feb 2007 Location: Dublin	Hey Znyper, Don't give up on this so quickly - I have a dreambox (500C) also & have thought along the same lines as you. Good to find somebody else here. I started a thread about this but it took off in another direction SqueezBox substitute Maybe we could combine our ideas & come up with something better sounding. I opened up the box and found a PCM1725 delta-sigma DAC which can take either normal or I2S input signals & voltage outputs. It accepts sampling frequencies 16KHz to 96KHz & operates off 5V supply. http://www.google.com/url?sa=t&ct=re...7sk7bRx4_C83Kw Perhaps inmates could suggest a substitute with better sonics or we could improve existing output circuit. I've been meaning to look at this anyway as the sound output is pretty low & I believe this could be improved. One immediate improvement would be changing the output caps the signal passes through for something better. Let me know what you think!

13th January 2008, 02:30 AM	#8
jkeny Banned Join Date: Feb 2007 Location: Dublin	Another improvement would be to change the op-amp circuit that signal goes through - maybe a better op-amp & surrounding circuitry. Of course we could just take the spdif out signal & feed it into an external DAC & then an amplifier!

15th January 2008, 02:40 AM	#9
dj_oatmeal diyAudio Member Join Date: Mar 2006 Location: Columbia, South Carolina	I don't know if it can be done but the price is right. I would look into the Playstation as Cd player thread and see if is possible to feed the DAC on the Playstation from an external device and get it to output. You can get them in the US for about $20-$30 fairly easily. This same concept may be in my future as I have an SMC SMCWAA-G on the way from ebay (it is similar to the Dreambox/Squeezbox).

15th January 2008, 08:52 AM	#10
jkeny Banned Join Date: Feb 2007 Location: Dublin	Thanks dj, First though, I think it's possible to improve the Dreambox internals before going to an external DAC I'm hoping znyper and/or somebody else with a dreambox can collaborate on these improvements!