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-   -   DIY active cable (http://www.diyaudio.com/forums/solid-state/13007-diy-active-cable.html)

Koy 27th March 2003 11:15 PM

DIY active cable
 
Doing experiments with interlink (signal) cables I noticed I was not able to find the the optimal one. Even trying more expensive one. Browsing on the net I discovered very interesting solution - an active cable, by author called AudioBuffer - http://www.pha.inecnet.cz/macura/buffer_en.html. Not expensive, simple circuit. What do you think about?

Bill Fitzpatrick 28th March 2003 01:58 AM

Link is no good.

seangoesbonk 28th March 2003 02:28 AM

Should be:
http://www.pha.inecnet.cz/macura/buffer_en.html

Cradle22 28th March 2003 08:24 AM

Hi!

Looks nice, although I I use an OPA134, I would also use it as a balanced line driver (since this is what OPA134 is for).

Of course, then you will need to use the corresponding de-balancing circuit (don't know the OPA nr right now), unless you have balanced inputs on your amplifier...

But sometimes I will check it out (I have some of those OPAs lying around...)


Bye,

Arndt

carlmart 28th March 2003 11:12 AM

Quote:

Originally posted by Cradle22

Looks nice, although I I use an OPA134, I would also use it as a balanced line driver (since this is what OPA134 is for).

Of course, then you will need to use the corresponding de-balancing circuit (don't know the OPA nr right now), unless you have balanced inputs on your amplifier...

But sometimes I will check it out (I have some of those OPAs lying around...)



I think you are mixing up the letters: the balanced driver is the DRV134. The OPA134 is a regular opamp.



Carlos

carlosfm 28th March 2003 02:42 PM

it's only a buffer...
 
Hi,
Is the op-amp really needed?:scratch:
Don't think so.
Only if you need the gain, in case of a headphone amp.
The buf634 alone has 250 ma current drive, not 200 as it says on that link.

Koy 28th March 2003 02:50 PM

Gainf of the BUF is lower than 1 ( about 0.9) i.e. you need gain stage to correct it. Unless you accept attenuation of the signal.

carlosfm 28th March 2003 04:49 PM

BUF634
 
Koy,

You have a point there.
But on the datasheet you can see:

GAIN:
RL = 1k, VO = 10V 0.95 0.99 [ [ V/V
RL = 100, VO = 10V 0.85 0.93 [ [ V/V
RL = 67, VO = 10V 0.8 0.9 [ [ V/V

I suppose that above 1kohm load it's unity gain...:scratch:

PMA 28th March 2003 05:14 PM

Carlosfm,
yes, the opamp is needed. It estimates the overall behavior of the circuit, the BUF634T is there to
1) deliver enough current to drive matched cable,
2) to eliminate capacitive load
3) to minimize thermal feedback on OA chip
It results in considerably better sound. Though it might seem not making sense, it really does. The best way is to try it.

PMA 28th March 2003 05:17 PM

Carlosfm,
there is a load of 50 Ohm + 50 Ohm, i.e. 100 Ohm. The terminating resistor of 50 Ohm is a must. Omitting it all the effect disappears.


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