most of the modern high end DAC chips have 2Vrms balanced outputs (+1V -1V)
most of the nice sounding pass amps (M2 F3 F4 F6 ZV9) have unbalanced input
To connect them together I need a preamp or converter (unity gain) to go from balanced to unbalanced. I would like to avoid transformers... Any advice for a schema?
I could use only the + output of the DAC but then only 1Vrms, this is a pity
most of the nice sounding pass amps (M2 F3 F4 F6 ZV9) have unbalanced input
To connect them together I need a preamp or converter (unity gain) to go from balanced to unbalanced. I would like to avoid transformers... Any advice for a schema?
I could use only the + output of the DAC but then only 1Vrms, this is a pity
FYI - Some top DAC chips still feature current outputs, such as T.I.'s PCM179x series. These require seperate current-to-voltage conversion circuitry.
Yes, it possible to utilize only one-half of an balanced output. There likely is little sound quality sacrificed, aside from ground-loop noise rejection. Having only 1VRMS oitput level should not present any problem either, unless, maybe, you use an passive preamp. That said, the vast majority of commercial DAC boxes include single-ended RCA outputs. Even those DAC boxes with balanced outputs also typically feature a set of single-ended RCAs.
Yes, it possible to utilize only one-half of an balanced output. There likely is little sound quality sacrificed, aside from ground-loop noise rejection. Having only 1VRMS oitput level should not present any problem either, unless, maybe, you use an passive preamp. That said, the vast majority of commercial DAC boxes include single-ended RCA outputs. Even those DAC boxes with balanced outputs also typically feature a set of single-ended RCAs.
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I am speaking about DAC chips, not DAC boxes with rca and xlr output...
Yes there are top DAC chips with current output, then use 2X pass D1 or similar mosfet I/V converter and obtain the balanced + and - 2Vrms output.
To feed it to unbalanced amp I need this preamp/converter ....
No other preamp before the F3 (F4) only a passive volume Pot
Yes there are top DAC chips with current output, then use 2X pass D1 or similar mosfet I/V converter and obtain the balanced + and - 2Vrms output.
To feed it to unbalanced amp I need this preamp/converter ....
No other preamp before the F3 (F4) only a passive volume Pot
No balanced to SE converter sounds as good as using just one phase. It is perhaps a technically compromised choice, but as for the sound...imho only of course.
The balanced DAC chips are best utilised with balanced preamps and balanced poweramps.
If you do use an active preamp, or a TVC it makes sense to leave all these SE >BAL > SE conversions to the preamp, without involving extra circuitry.
Manufacturers generally handle these issues in an appalling way. Even in supposedly high end products they don't think twice about doing the BAL > SE conversion through an opamp, or adding a balanced output again with an inverting opamp.
The balanced DAC chips are best utilised with balanced preamps and balanced poweramps.
If you do use an active preamp, or a TVC it makes sense to leave all these SE >BAL > SE conversions to the preamp, without involving extra circuitry.
Manufacturers generally handle these issues in an appalling way. Even in supposedly high end products they don't think twice about doing the BAL > SE conversion through an opamp, or adding a balanced output again with an inverting opamp.
There's quite a few pertinent lateral options here...
Aleph's (balanced inputs)
Any x'd amp (the F5 - X is a beautifully documented one )
The diy opamp article at first watt could be used as a converter easily enough.
Ummmm, put a jc-2 (basically a balanced inputs ba-3 ...ish) in front of whatever pass output stage you like?
X100 or similar clone?
Ba1 front end on a output stage of your own choosing?
Balanced zv9 (the donut thread is awesome)
And finally there's a dac I/v converter article from pass also...
So, really, you're spoiled for choice!
Aleph's (balanced inputs)
Any x'd amp (the F5 - X is a beautifully documented one )
The diy opamp article at first watt could be used as a converter easily enough.
Ummmm, put a jc-2 (basically a balanced inputs ba-3 ...ish) in front of whatever pass output stage you like?
X100 or similar clone?
Ba1 front end on a output stage of your own choosing?
Balanced zv9 (the donut thread is awesome)
And finally there's a dac I/v converter article from pass also...
So, really, you're spoiled for choice!
If you are speaking only of DAC chips, I think that your nst perfoming solution ks to simply take one of the chip's differential output phases in single-ended form. With current output DACS, you can short the unused output phase to signal ground. With voltage output DACs, you leave the unused output phase open.
As for the maximum output signal, it is settable to whatever maximum voltage you need via the active I/V stage with a current DAC chip. As for voltage output DAC chips, 1VRMS maximum may still be high enough, even with a passive volume pot. This is very likely true for your particular system should you very seldom have the volume pot. rotated to maximum when fed an standard 2VRMS input level.
John Broskie makes a BAL -> Unbalanced converter, it's worth an email to see if he might have a spare PCB around to sell...
BCF PCB and Kit
BCF PCB and Kit
There are many discrete circuits that can convert balanced to unbalanced.
One of the classics is the Borbely EB602/200 and its variants.
Just use the -IN to connect to the negative phase instead of Gnd.
While discete, they are opamp like circuits (similar to the Pass discrete opamp) and hence has high NFB.
The Borbely is single ended, and is temperature stable due to its choice of components.
If you wish to go for circuits without NFB, take a look at the XCEN :
The XCEN -- Balanced to Single Ended Converter
We now have an updated version that does not have the drift.
Even a SMD version :
http://www.diyaudio.com/forums/the-...owtorch-preamplifier-ii-1963.html#post5270193
For even lower distortion, our HAGS does exceptionally well.
But it requires lots of Toshiba unobtainiums.
http://www.diyaudio.com/forums/head...ss-zgf-headphone-amplifier-4.html#post4296102
Patrick
One of the classics is the Borbely EB602/200 and its variants.
Just use the -IN to connect to the negative phase instead of Gnd.
While discete, they are opamp like circuits (similar to the Pass discrete opamp) and hence has high NFB.
The Borbely is single ended, and is temperature stable due to its choice of components.
If you wish to go for circuits without NFB, take a look at the XCEN :
The XCEN -- Balanced to Single Ended Converter
We now have an updated version that does not have the drift.
Even a SMD version :
http://www.diyaudio.com/forums/the-...owtorch-preamplifier-ii-1963.html#post5270193
For even lower distortion, our HAGS does exceptionally well.
But it requires lots of Toshiba unobtainiums.
http://www.diyaudio.com/forums/head...ss-zgf-headphone-amplifier-4.html#post4296102
Patrick
Thanks for all advices
I will have a look at all
my goal is to keep it as simple as possible.
Unfortunately 1Vrms is too low, otherwise I would use one phase of the dac
and skip all this
Another idea, would it be possible to combine 2X D1 I/V converters so that it makes the I/V converiosn and the bal => unbal ?
I will have a look at all
my goal is to keep it as simple as possible.
Unfortunately 1Vrms is too low, otherwise I would use one phase of the dac
and skip all this
Another idea, would it be possible to combine 2X D1 I/V converters so that it makes the I/V converiosn and the bal => unbal ?
Aleph P is back!! (limited time offer)
negative to ground (usually by a dip switch or on this board by a relay). mind you I never used it in this mode, only bal>bal
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