Hum when using DAT-OUT connection

Archived from groups: rec.audio.tech (More info?)

On 28 Feb 2005 17:24:48 -0800, John_Pankowicz@hotmail.com wrote:

>I have a Sony Mini HiFi with the following connections: AUX-IN, DAT-IN
>and DAT-OUT. I want to connect it to my PC. I have an external
>SoundBlaster.
>
>When I connect the SoundBlaster line-out to either the AUX-IN or DAT-IN
>of the HiFi, everything works fine. I can play PC files over the HiFi.
>But when I connect the DAT-OUT to the SoundBlaster line-in, not only do
>I get nothing in the PC when trying to capture a wav file, but I get a
>very loud hum in the HiFi whenever I switch to DAT.
>
>Is there some kind of mis-match between connections?
>
>Thanks for any advise.
>
>John

hi john
the problem is caused by a ground loop, the cure is to wire isolating
transformers (one for each channel) in line.
these things are called 600 ohm - 600 ohm line isolating transformers.
and can be quite expensive.

a good (cheap) solution to this is availible for audio systems in car
systems, these have two transformers in one box and conveniently come
pre wired with phono plugs and sockets here is an example from uk
supplier, and can be used both ways , ie record or playback. the down
side is they are not the hi est of fi but good enough for computer use
and worth a try at the price
http://www.maplin.co.uk/Module.aspx?ModuleNo=33172&TabI...
hope this helps
regards
bob

Archived from groups: rec.audio.tech (More info?)

Thanks Bob,

I went down to the local Radio Shack and bought their version of an
"Audio System Ground Loop Isolator" (Cat. # 270-054, $17 US) This
solved my problem with capturing the HiFi output on my PC. I was able
to capture a wave file on the PC. Now I can transfer some of my
cassette tapes to the PC. Thanks again.

Hwwever, I still have a problem. If I have both line-in and line-out
connected at the same time, I still get a loud hum. I bought two ground
loop isolators and have one on line-in and one on line-out from the
SoundBlaster. If I run line-out to DAT-IN on the HiFi, I get a bassy
sounding hum whenever I switch the HiFi to DAT. If I run line-out to
AUX-IN on the HiFi, I get a higher pitched sounding hum whenever I
switch the HiFi to AUX.

John


burbeck wrote:
> On 28 Feb 2005 17:24:48 -0800, John_Pankowicz@hotmail.com wrote:
>
> >I have a Sony Mini HiFi with the following connections: AUX-IN,
DAT-IN
> >and DAT-OUT. I want to connect it to my PC. I have an external
> >SoundBlaster.
> >
> >When I connect the SoundBlaster line-out to either the AUX-IN or
DAT-IN
> >of the HiFi, everything works fine. I can play PC files over the
HiFi.
> >But when I connect the DAT-OUT to the SoundBlaster line-in, not only
do
> >I get nothing in the PC when trying to capture a wav file, but I get
a
> >very loud hum in the HiFi whenever I switch to DAT.
> >
> >Is there some kind of mis-match between connections?
> >
> >Thanks for any advise.
> >
> >John
>
> hi john
> the problem is caused by a ground loop, the cure is to wire isolating
> transformers (one for each channel) in line.
> these things are called 600 ohm - 600 ohm line isolating
transformers.
> and can be quite expensive.
>
> a good (cheap) solution to this is availible for audio systems in car
> systems, these have two transformers in one box and conveniently come
> pre wired with phono plugs and sockets here is an example from uk
> supplier, and can be used both ways , ie record or playback. the down
> side is they are not the hi est of fi but good enough for computer
use
> and worth a try at the price
>
http://www.maplin.co.uk/Module.aspx?ModuleNo=33172&TabI...
> hope this helps
> regards
> bob

Archived from groups: rec.audio.tech (More info?)

hi john,
the best way to think of this set up is to connect the computer as you
would a tape machine, ie :-
line out to dat play (dat in)
line in to dat record (dat out)
along with the isolating transformers this should work fine
to play from the computer select dat on hi fi,
to record select the source on hi fi , set levels on soundblaster
recorder, every thing should be fine
regards
bob

On 2 Mar 2005 13:54:50 -0800, John_Pankowicz@hotmail.com wrote:

>Thanks Bob,
>
>I went down to the local Radio Shack and bought their version of an
>"Audio System Ground Loop Isolator" (Cat. # 270-054, $17 US) This
>solved my problem with capturing the HiFi output on my PC. I was able
>to capture a wave file on the PC. Now I can transfer some of my
>cassette tapes to the PC. Thanks again.
>
>Hwwever, I still have a problem. If I have both line-in and line-out
>connected at the same time, I still get a loud hum. I bought two ground
>loop isolators and have one on line-in and one on line-out from the
>SoundBlaster. If I run line-out to DAT-IN on the HiFi, I get a bassy
>sounding hum whenever I switch the HiFi to DAT. If I run line-out to
>AUX-IN on the HiFi, I get a higher pitched sounding hum whenever I
>switch the HiFi to AUX.
>
>John
>
>

Archived from groups: rec.audio.tech (More info?)

Bob,

I have them connected as you suggest, with isolating transformers on
each pair of lines. Line-out to dat-in works. Line-in to dat-out works.
But I can't leave them both connected at the same time, or I get hum
when I switch to DAT on the HiFi.

I guess I can live with just switching the connections when I need to.

John


burbeck wrote:
> hi john,
> the best way to think of this set up is to connect the computer as
you
> would a tape machine, ie :-
> line out to dat play (dat in)
> line in to dat record (dat out)
> along with the isolating transformers this should work fine
> to play from the computer select dat on hi fi,
> to record select the source on hi fi , set levels on soundblaster
> recorder, every thing should be fine
> regards
> bob
>
> On 2 Mar 2005 13:54:50 -0800, John_Pankowicz@hotmail.com wrote:
>
> >Thanks Bob,
> >
> >I went down to the local Radio Shack and bought their version of an
> >"Audio System Ground Loop Isolator" (Cat. # 270-054, $17 US) This
> >solved my problem with capturing the HiFi output on my PC. I was
able
> >to capture a wave file on the PC. Now I can transfer some of my
> >cassette tapes to the PC. Thanks again.
> >
> >Hwwever, I still have a problem. If I have both line-in and line-out
> >connected at the same time, I still get a loud hum. I bought two
ground
> >loop isolators and have one on line-in and one on line-out from the
> >SoundBlaster. If I run line-out to DAT-IN on the HiFi, I get a bassy
> >sounding hum whenever I switch the HiFi to DAT. If I run line-out to
> >AUX-IN on the HiFi, I get a higher pitched sounding hum whenever I
> >switch the HiFi to AUX.
> >
> >John
> >
> >

Archived from groups: rec.audio.tech (More info?)

On 5 Mar 2005 07:12:22 -0800, John_Pankowicz@hotmail.com wrote:

>Bob,
>
>I have them connected as you suggest, with isolating transformers on
>each pair of lines. Line-out to dat-in works. Line-in to dat-out works.
> But I can't leave them both connected at the same time, or I get hum
>when I switch to DAT on the HiFi.
>

the only thing i can think of is that you have dat in and dat out
mixed up, try swapping them

failing thar turn the record volume right down on the soundblaster
when listening,
bob