Can I use a TV converter box as a DAC

srinath · 13th May 2010, 04:29 PM

OK here is another DAC question and bound to be really stupid.

I see a lot of digital to analog converter boxes for TV @ flea/GW/trash dumps.

They take audio and video inputs and convert it all to analog.
Can I use one of those as an external DAC ?
Is it a question of quality (or lack there of).

Now what DAC chips are in them ?

Thanks in advance.
Cool.
Srinath.

benb · 13th May 2010, 05:46 PM

The short answer: Maybe, but you wouldn't want to.

For one, it's a question of bandwidth and resolution. The video signal bandwidth is a couple of MHz wide (overkill for audio, but that doesn't actually disqualify it for audio), and perhaps 8 bits resolution (for video brightness and/or color), definitely not enough for Good Audio.

There's also (I'm just presuming what I think SHOULD be in there) a DAC for the audio signal that gets sent to the TV as FM, but that's at best the same as the sound chip on a computer motherboard.

I haven't opened up one of these, but I'd suspect the "converter" is one or a very few chips with lots of pins and that do lots of internal processing, and it may be impossible to even access something to use as an audio ADC separately from the rest of the circuitry. It may be fun to take apart, but I wouldn't expect much of value other than plugging into an old analog TV.

leadbelly · 13th May 2010, 06:00 PM

I suspect the poster is actually asking if he can take the TV box as a whole, unmodified, hook a CD transport to the input, and get analog audio output. The answer is no.

Also, I suspect that you are actually talking about analog cable boxes that aren't digital whatsoever, since around here digital boxes for cable and satellite are new enough that people usually resell them and don't just throw them out.

srinath · 13th May 2010, 06:05 PM

I sorta want to use the digital to analog box with minimal mods if it will work.
I see lots of the new style cable boxes starting @ 5 bucks around here at all GW/thrift/fleas. Forget the old type analog boxes. Digital to analog is common enough and cheap anough. I mean new they got for under 30 bucks like this one -
MAGNAVOX TB110MW9 DTV Digital to Analog Converter Box - eBay (item 330409867857 end time May-30-10 12:55:26 PDT)
Cool.
Srinath.

infinia · 06:16 PM

set top box STB
FYI It's probably buried in a highly packed function LSI device either on the uPcontroller side or last conversion/demodulator.
BTW as a minimum you probably need to build a I2C controller to talk to it.

What I do is open it up & get the device # and obtain the data sheet from the OEM. If the parts data is confidential. Contact a rep and tell them it's a potentially new application for India but its secret. LOL

srinath · 13th May 2010, 06:54 PM

The fetishator is easy enough, I'll just gut my kenny and try it and if it works, I'd gut the other kenny and do the tubes lampizator, I think this is just more work than needed.

Cool.
Srinath.

infinia · 13th May 2010, 06:57 PM

they killed kenny!!

srinath · 13th May 2010, 08:33 PM

Quote:

Originally Posted by infinia

they killed kenny!!

Not on my watch.
I got 2 that are well very much functioning and sound OK and I have remotes for. The carousel style I got free in doa condition and got working ... so yea a dead kenny can come back to life ... anyway, that carousel type I'd first do the fet mod. If it works, I'd swap that with the cartridge type and use it while I mod the cartridge with tube. I like the cartridge one a bit more already ... I think it sounds better and is probably a shade older though both are atleast 15 years old. That cartridge stype the DP-M5550 was my main CD since new in 1994. Its als old as my marriage and works just as well and no you may not know where the cd goes in my marriage.
The DP-r4550 I got free a month ago from a friend, I fixed 2 days ago and may need some cleaning etc, but it sounds a wee bit lifeless at this point.
The carousel IMHO is less versatile than the cartridge as well as needing extra room in front.
I'd open it and try the fet mod first I thnk.
Cool.
Srinath.

srinath · 14th May 2010, 12:18 AM

OK I got a toshiba TC9237BN in that kenny with carousel.
And I found a datasheet for it - http://jp.ic-on-line.cn/IOL/datashee...7bf_118895.pdf

Sadly I am not smart enough to be able to tell where the output comes out of that.
My guess is 5 or 6 for right and 9 or 10 for left. That correct ? no ? can someone point it out.

Also the carousel is a lot bigger than I thought, but can squeeze in on the side of it ... especially the FET type ones.
Thanks.
Srinath.

13th May 2010, 04:29 PM	#1
srinath diyAudio Member Join Date: Feb 2010	Can I use a TV converter box as a DAC OK here is another DAC question and bound to be really stupid. I see a lot of digital to analog converter boxes for TV @ flea/GW/trash dumps. They take audio and video inputs and convert it all to analog. Can I use one of those as an external DAC ? Is it a question of quality (or lack there of). Now what DAC chips are in them ? Thanks in advance. Cool. Srinath.

13th May 2010, 06:00 PM	#3
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	I suspect the poster is actually asking if he can take the TV box as a whole, unmodified, hook a CD transport to the input, and get analog audio output. The answer is no. Also, I suspect that you are actually talking about analog cable boxes that aren't digital whatsoever, since around here digital boxes for cable and satellite are new enough that people usually resell them and don't just throw them out. __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

13th May 2010, 06:10 PM	#5
infinia diyAudio Member Join Date: May 2005 Location: Californication	set top box STB FYI It's probably buried in a highly packed function LSI device either on the uPcontroller side or last conversion/demodulator. BTW as a minimum you probably need to build a I2C controller to talk to it. What I do is open it up & get the device # and obtain the data sheet from the OEM. If the parts data is confidential. Contact a rep and tell them it's a potentially new application for India but its secret. LOL __________________ like four million tons of hydrogen exploding on the sun like the whisper of the termites building castles in the dust Last edited by infinia; 13th May 2010 at 06:16 PM.

13th May 2010, 06:57 PM	#7
infinia diyAudio Member Join Date: May 2005 Location: Californication	they killed kenny!! __________________ like four million tons of hydrogen exploding on the sun like the whisper of the termites building castles in the dust

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13th May 2010, 05:46 PM	#2
benb diyAudio Member Join Date: Apr 2010	The short answer: Maybe, but you wouldn't want to. For one, it's a question of bandwidth and resolution. The video signal bandwidth is a couple of MHz wide (overkill for audio, but that doesn't actually disqualify it for audio), and perhaps 8 bits resolution (for video brightness and/or color), definitely not enough for Good Audio. There's also (I'm just presuming what I think SHOULD be in there) a DAC for the audio signal that gets sent to the TV as FM, but that's at best the same as the sound chip on a computer motherboard. I haven't opened up one of these, but I'd suspect the "converter" is one or a very few chips with lots of pins and that do lots of internal processing, and it may be impossible to even access something to use as an audio ADC separately from the rest of the circuitry. It may be fun to take apart, but I wouldn't expect much of value other than plugging into an old analog TV.

13th May 2010, 06:05 PM	#4
srinath diyAudio Member Join Date: Feb 2010	I sorta want to use the digital to analog box with minimal mods if it will work. I see lots of the new style cable boxes starting @ 5 bucks around here at all GW/thrift/fleas. Forget the old type analog boxes. Digital to analog is common enough and cheap anough. I mean new they got for under 30 bucks like this one - MAGNAVOX TB110MW9 DTV Digital to Analog Converter Box - eBay (item 330409867857 end time May-30-10 12:55:26 PDT) Cool. Srinath.

13th May 2010, 06:54 PM	#6
srinath diyAudio Member Join Date: Feb 2010	The fetishator is easy enough, I'll just gut my kenny and try it and if it works, I'd gut the other kenny and do the tubes lampizator, I think this is just more work than needed. Cool. Srinath.

14th May 2010, 12:18 AM	#9
srinath diyAudio Member Join Date: Feb 2010	OK I got a toshiba TC9237BN in that kenny with carousel. And I found a datasheet for it - http://jp.ic-on-line.cn/IOL/datashee...7bf_118895.pdf Sadly I am not smart enough to be able to tell where the output comes out of that. My guess is 5 or 6 for right and 9 or 10 for left. That correct ? no ? can someone point it out. Also the carousel is a lot bigger than I thought, but can squeeze in on the side of it ... especially the FET type ones. Thanks. Srinath.

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