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Audio baluns for sound card input?

J

Joerg

Jan 1, 1970
0
Hello Michael,
... I still have one I made 20 years ago
with a R.L. Drake tuning knob on the box. ...

Ah, Drake. Was it the style of knobs found on the Drake 2B? That was one
of the most beautiful designs I have ever seen. Both from an aesthetics
point of view and with respect to the circuitry.

Regards, Joerg
 
J

Joerg

Jan 1, 1970
0
Hello Graham,
Transformers with *respectable audio performance* are neither especially
cheap nor common. Not much demand for them these days either.

True but you can buy them. The Muxlab versions are pretty good but AFAIR
they were about $40 a pop.

Regards, Joerg
 
J

Joerg

Jan 1, 1970
0
Hello Graham,
Funny you should mention that John. Back in 1989/90 I designed a simple
differential video buffer for EMI studios to solve just such a problem.
They used bucketloads of them. I'm not aware if there was an equivalent
'off the shelf' product ( certainly at a sensible price ) that could do the
job.

With the good old uA733 in the first stage? I designed a lot of stuff
with these because they were an absolute bargain.

Regards, Joerg
 
J

Joerg

Jan 1, 1970
0
Hello John,
AFAIK, they are only called baluns by **RF** people, not audio people.

I grew up in RF but was surprised when I heard audio folks asking where
the box with baluns was. The people that rig up the gear for rock bands.
Maybe they aren't the typical audio expert. But they usually did have a
lot of tatoos.

Regards, Joerg
 
M

Michael A. Terrell

Jan 1, 1970
0
Joerg said:
Hello Michael,


Ah, Drake. Was it the style of knobs found on the Drake 2B? That was one
of the most beautiful designs I have ever seen. Both from an aesthetics
point of view and with respect to the circuitry.

Regards, Joerg

I believe that it was the 4C series. It has the finger hole for
quick tuning, but someone tried to be helpful and laid a hot soldering
iron on it during an emergency repair at a Cable TV Headend.

I have a friend who worked QC at Drake in Miamisburg and it was
rejected for a minor scratch on the inlay. I also got a handful of
scrap UV3 frequency display boards that were run through their wave
solder machine before it was at the proper temperature. They were just
starting up the production line and didn't have the profile set up
right. One had over a pound of excess solder on it. Some IC's were
completely covered with solder. That board was a real challenge to
repair with nothing but the IC data sheets and the pinouts for the
board. I got most of them working but I don't remember what I did with
them.
 
P

Pooh Bear

Jan 1, 1970
0
Joerg said:
Hello Fred,


That's a good idea to test a ground loop w/o the power supply. I suspect
it'll be clean though because we also use other gear there, such as a
cassette deck for recording. Those are grounded and work fine.

The laptop is said to work ok with its power supply and a mike, just not
when connected to the other (grounded) equipment.

That figures.

What does the interference sound like when it's connected to grounded
equipment ?

Graham
 
P

Pooh Bear

Jan 1, 1970
0
Joerg said:
Hello Graham,


Thanks. That is not very expensive at all. We'll see what the RS
transformer does. It should at least improve things noticably but if it
leaves noise then, yes, it will be time for a DI box. But maybe a
passive one because the Ultra-DI needs phantom power (which we have but
it increases the number of cables) or a 9V battery.

I have to admit I prefer 'passive' DIs myself. I'm surprised Behringer don't do
one.

Good luck anyway.


Graham
 
P

Pooh Bear

Jan 1, 1970
0
Joerg said:
Hello Graham,


True but you can buy them. The Muxlab versions are pretty good but AFAIR
they were about $40 a pop.

Over here, one of the better small commonly available 'line level
transformers' you can get is made by OEP.

http://www.oep.co.uk/

RS components stock some of them. I don't know if you meant Radio Shack or RS
components when you said you were getting a transformer form RS.

Graham
 
J

Joerg

Jan 1, 1970
0
Hello Graham,
Over here, one of the better small commonly available 'line level
transformers' you can get is made by OEP.

http://www.oep.co.uk/

Nice. I think it is great that some smaller companies still make good
audio iso transformers. It is no problem to produce RF versions but
audio with hundreds of turns is a pain and I'd rather buy them.
RS components stock some of them. I don't know if you meant Radio Shack or RS
components when you said you were getting a transformer form RS.

Sorry, I meant Radio Shack. Should have known since I have lived in
Europe and have dealt with RS.

Regards, Joerg
 
J

Joerg

Jan 1, 1970
0
Hello Graham,
What does the interference sound like when it's connected to grounded
equipment ?

I haven't heard it much but the person who did the recording said it is
hash (not just 60Hz plus harmonics).

Regards, Joerg
 
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