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DAC problems


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#1 storkysr

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Posted 28 December 2011 - 03:14 PM

I bought a Toshiba 55sl417u LED backlit LCD TV which has only DIGITAL audio outputs. In order to input the audio to the RCA jacks of my Sherwood receiver I bought a small DAC. The DAC seems to have specs that are compatable (20-20KHz response, >80 db s/n, < .1% THD, PCM tosslink input, RCA outputs, etc). However, when hooked up I get only a "sputtering" noise from my stereo. I tried inputting the DAC directly from the optical-out of my cable box (toss link) with the same results. :pullhair: Is the DAC defective or am I doing something wrong? Thanks in advance.

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#2 terry1966

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Posted 28 December 2011 - 09:55 PM

i'm no expert in this area but it sounds to me like the signal from the dac to the sherwood isn't strong enough(not enough voltage) to produce sound output so i'd be thinking you need an amplifier to go between the dac and the sherwood. like i said no expert but that's my first thought. :popcorn:

#3 storkysr

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Posted 28 December 2011 - 10:19 PM

The spec for the output of the DAC is 1.7V which seems to me to be plenty to input into the preamp of the Sherwood. Unless, of course, the DAC is defective. Thanks for your thought

#4 terry1966

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Posted 28 December 2011 - 10:48 PM

do you have a link to the sherwoods model/specs? :popcorn:

Edited by terry1966, 28 December 2011 - 10:51 PM.


#5 terry1966

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Posted 28 December 2011 - 11:39 PM

i've been looking at the specs of the tv and it does seem to have a mini jack analogue sound output that might be worth trying straight to the sherwood, and see if that gives you sound. also had another thought do you have to change any audio settings on the tv before it will output sound to the dac using the digital connection before it'll work and you get sound out of the sherwood? :popcorn:

Edited by terry1966, 28 December 2011 - 11:46 PM.


#6 storkysr

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Posted 29 December 2011 - 01:01 PM

The TV does have an output labeled "fixed audio" which is analog. However I get a loud 60 Hz ground loop when I connect to the receiver with regular RCA plugs. The house wiring is old and I am using three prong adapters. I'm thinking that the fact that I get the same "sputtering" when connected by TOS LINK optical connector right from the cable box may indicate a problem with the DAC(?)

#7 storkysr

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Posted 29 December 2011 - 03:06 PM

AND: no adjustments are needed to enable the op-out from the TV. It is supposed to be always "hot" (I can see the red light come thru the cable. Thanks.

#8 terry1966

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Posted 29 December 2011 - 11:49 PM

no i wouldn't jump to the conclusion the problem is with the dac yet, so far you don't seem to have gotten any sound from the tv outputs, so maybe try a different speaker system say your pc's speakers and see if you get sound, once you know the sound is being outputted then you can look to the dac or sherwood as the problem. sorry can't be of any more help and all i can suggest is trying different combinations of source and sound output until you can narrow it down to where the problem may be. :popcorn:

#9 storkysr

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Posted 30 December 2011 - 11:17 AM

I get great sound from the Sherwood when driven by the analog outs of the cable box but get the "sputtering from the op-outs from the same box (thru the DAC to the Sherwood) and, like I said, I get good sound from the TV's "Fixed Audio" analog out direct to the Sherwood EXCEPT for the LOUD ground hum. Just had a thought - could there be an incompatability regarding Dolby encoding and the DAC? BTW-the DAC is 192khz/24 bit.

#10 terry1966

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Posted 31 December 2011 - 06:28 AM

i've no idea but wouldn't of thought so. sorry can't think of anything else to suggest except maybe visiting a dedicated a/v forum that should have experts in the setup/troubleshooting of all home theatre audio equipment and connections. do let us know if you find the problem/fix tho please because i'd be interested to know and it may help someone in the future with a similar problem. :popcorn: had a look into the dolby sound and yes it seems that may well be your problem, i'd assumed the tv/box was outputting in 2 channel stereo mode, but it seems they may be outputting in 5.1 so yes you'd need to make sure the box or tv only outputs in 2ch stereo into the dac and then it should work.

Edited by terry1966, 31 December 2011 - 07:33 AM.


#11 storkysr

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Posted 31 December 2011 - 01:06 PM

Yeah, Dolby may be the problem. Thanks for your thoughts. I'll let you know when I get to the bottom of this.

#12 bradjp92

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Posted 14 December 2012 - 12:56 AM

Any updates?




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