Tapedeck unbalanced output to that 1246

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duende

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Hi,
I have a tapedeck that  i want to use to transfer. My analog to digital converter manual ( crookwood ) don't recommend to connect unbalanced gear due to specific electronic balanced in/out...

I can connect output deck to a diy baxendall eq with that 1246 input and 1646 ouput to banlance the signal before the AD, but i don't know if That 1246 accept unbalanced input ? The tapedeck output impedance is 2Kohm.

Other solution, i have some pcb with 1246/1646 that i can configure with flexibility, a buffer + 1646 could work ? What's the best way to adapt and fix input buffer impedance ?
 

abbey road d enfer

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duende said:
I have a tapedeck that  i want to use to transfer. My analog to digital converter manual ( crookwood ) don't recommend to connect unbalanced gear due to specific electronic balanced in/out...
I doubt the converter have issues when connecting its input to unbalanced sources. I can see why it does not like its outputs being connected to unbalanced, though. I'm 99% certain it's the old "Tascam problem".

i don't know if That 1246 accept unbalanced input ?
Indeed it does. I recommend using balanced wiring, i.e. using 2cond+shield, joining cold and shield at the unbalanced connction, for eliminating ground loop noise.

The tapedeck output impedance is 2Kohm.
The input impedance of the 1246 is 24k, so loading is less than 1dB.

Other solution, i have some pcb with 1246/1646 that i can configure with flexibility, a buffer + 1646 could work ?
This question confuses me. You want both ways, correct? U to B from tape to converter, and B to U from converter to tape, right?
So I would say you need a 1246 between tape output and converter and 1646 between  converter and tape input.
If you already have them, 1246+1646 would be usable for all connections, since the 1246 can receive  both balanced and unbalanced sources and 1646 can drive both balanced and unbalanced inputs.

This last question confuses me. What's the best way to adapt and fix input buffer impedance ?
Don't fret about impedances. THAT circuits are designed for bridging connections, not matching. Bridging assumes a source impedance that's much lower (< 1/10th) than the receiver impedance.
Impedance matching (meaning source Z is equal to load Z) is a thing of the past, AFA audio is concerned.
 

mjrippe

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Also, your DIY EQ will work fine.  If it has a true bypass, even better. 

There are also many -10dBV to +4dBu converter boxes if your tape deck is a consumer unit.  This will bring the level up AND balance the signal.  Henry Matchbox and Aphex 124 are two popular ones.  The also do +4 bal to -10 unbal  :)
 

duende

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Thanks,

Yes i don't see the problem for unbalanced connexion but the manual put me in doubt, so i ask for that 1246 1646 also...

Crookwood installation guide :

The system will interface perfectly to any balanced gear.  However there may be some issues with
unbalanced gear and some issues with hum loops.
Unbalanced gear
You can connect the unbalanced output of any piece of external gear to the console without
problem.  You cannot connect the console to an unbalanced input without issues.  If you need to
do this, you will have to use an external unbalancing box, or speak to us and we will provide an
unbalancing card inside the racks for you to wire to.
Why is this?  Our consoles are completely symmetrical. There is equal circuitry on the hot phase
and the cold phase.  This is very unusual, but gives the consoles their superior sound. Most
manufacturers provide semi floating outputs that change from balanced to unbalanced if you
short the cold phase to ground.  However these circuits are imperfect.  By design they can actually
never be perfect, and the designer has to make them purposely imperfect in order fro them to
work. We just don’t use them.
Unbalanced gear is really problematical in a professional studio.  The designer usually either
makes it unbalanced because it’s designed for a home recording market, or because they believe
that the addition of a balanced input and output will corrupt the design. I agree about the floating
output stages, but every input has 2 phases: hot and cold, or hot and ground.  It makes huge sense
to provide a balanced input that can subtract and isolate you from any ground errors appearing in
the input signal, and it doesn’t even need any extra active stages if you are clever.
The real problem with unbalanced gear is that the safety ground is the same as the signal ground.
If any safety earth current flows down the signal ground wire, you’ll get hum. If you lift the safety
ground from the power supply, and a fault occurs, the chassis can become live. Ouch! Use an
unbalancer when you have to, and avoid all these issues.


But i can run the tape out to my eq, i can bypass the eq section and the signal goes through only 1246, an opamp for gain and 1646. For the next transfer project i will work like this but for the future i want build a balancer box for tapedeck, cause i have 5m cable between tapedeck and converters box.

I have pcb that i can configure like this :

1246 ------1646

or

unbalanced input ---- buffer ------1646


Is there a solution better than the other ?

I have also a wayene Kirkwood flat preamp , but designed for vinyl deck, maybe it works for tapedeck ?

https://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=7&t=753

Sorry for my bad english...

 

abbey road d enfer

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duende said:
Most manufacturers provide semi floating outputs that change from balanced to unbalanced if you
short the cold phase to ground.  However these circuits are imperfect.  By design they can actually
never be perfect, and the designer has to make them purposely imperfect in order fro them to
work. We just don’t use them.
That's what they say when they don't master the technology of Cross-Coupled Output Stages.

Unbalanced gear is really problematical in a professional studio.  The designer usually either
makes it unbalanced because it’s designed for a home recording market, or because they believe
that the addition of a balanced input and output will corrupt the design. I agree about the floating
output stages, but every input has 2 phases: hot and cold, or hot and ground.  It makes huge sense
to provide a balanced input that can subtract and isolate you from any ground errors appearing in
the input signal, and it doesn’t even need any extra active stages if you are clever.
The real problem with unbalanced gear is that the safety ground is the same as the signal ground.
If any safety earth current flows down the signal ground wire, you’ll get hum. If you lift the safety
ground from the power supply, and a fault occurs, the chassis can become live. Ouch! Use an
unbalancer when you have to, and avoid all these issues.[/i]

I have pcb that i can configure like this :

1246 ------1646

or

unbalanced input ---- buffer ------1646


Is there a solution better than the other ?
They're both good. The first possibility would offer a little more flexibility, if you wire the input as a balanced connection, using 2 cond +shied cable and joining cold and shield at the unbalanced side. Would completey eliminate ground loops.
 
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