The wiring is the same whether to balanced or unbalanced, it's just the connectors that change.
A balanced phono stage has, all things being equal, a 3 dB higher noise floor.. for the simple reason that the input signal seen by the + and - inputs with respect to ground is only half the the full voltage, while an unbalanced input sees the full voltage. (each input has 6dB more noise (or 6dB less signal for the same gain, if you prefer), but some of that noise cancels at the output together with the common mode noise, end result +3 dB)
Where low input noise is the primary concern (and for a phono stage, it should be) unbalanced is the preferred circuit topology.
A balanced phono stage has, all things being equal, a 3 dB higher noise floor.. for the simple reason that the input signal seen by the + and - inputs with respect to ground is only half the the full voltage, while an unbalanced input sees the full voltage. (each input has 6dB more noise (or 6dB less signal for the same gain, if you prefer), but some of that noise cancels at the output together with the common mode noise, end result +3 dB)
Where low input noise is the primary concern (and for a phono stage, it should be) unbalanced is the preferred circuit topology.
Yo.
The motive is to run the whole enchilada balanced:
re-re, reamp, ower amp. Is what i do, my rime TT has re-installed balanced outputs, yet to see a 2d standard-issue model. Not unusual if one lives in the balanced zone.
It's not even important to use different connectors, the standard RCA plug & socket works just fine as long as it's not earthed anywhere - if the electronics are fully balanced.
Our fully balanced RTP3D preamp has three phono inputs:
1. balanced XLR
2. balanced REDEL/Lemo, our house preference - simply the best sounding audio connector we have found
3/ a floating RCA socket which makes a perfect interface with 99% of good MC cart RCA equipped tone arms And even if the cable is a shielded unbalanced cable, as long as it's not grounded, I've never had any hum or other problems.
Regards, Allen
Our fully balanced RTP3D preamp has three phono inputs:
1. balanced XLR
2. balanced REDEL/Lemo, our house preference - simply the best sounding audio connector we have found
3/ a floating RCA socket which makes a perfect interface with 99% of good MC cart RCA equipped tone arms And even if the cable is a shielded unbalanced cable, as long as it's not grounded, I've never had any hum or other problems.
Regards, Allen
WoW started this tread couple of weeks ago and now loads of imput.
I have been running myne balanced for a while (LAC suply and passive RIA no caps on signal pat job whit silver revired arm)
Sound beter than what I had before but is one of those multy leghed critters job
so I was asking why not a balanced Pearl (may see Papa reply).
main advantages to me no noise from the input cables and just one resistor to adjust the gain
At present I am vorking on a balanced F5 but once done I was loking for a fully balanced set up.
Joachim Gerhard I am sorry I missed the Article can you drop me a link to it please?
Al
I have been running myne balanced for a while (LAC suply and passive RIA no caps on signal pat job whit silver revired arm)
Sound beter than what I had before but is one of those multy leghed critters job
so I was asking why not a balanced Pearl (may see Papa reply).
main advantages to me no noise from the input cables and just one resistor to adjust the gain
At present I am vorking on a balanced F5 but once done I was loking for a fully balanced set up.
Joachim Gerhard I am sorry I missed the Article can you drop me a link to it please?
Al
Al,
you'll have to wait for it to go public, or order a copy.
Linear Audio | your tech audio resource
Bksabath, here is my original schematic. The version shown was for a very demanding customer so it has some very expensive parts in it.
What is not shown is the servo. For more details i sugest you do youself a favour and get you a Linear Audio Vol.0. That bookzine has a lot of other interesting articles.
The servo shown there works only when you transfer balanced into unbalanced at the output. I designed a new servo that holds the DC offset to less then 1mV, single ended and differentially and it will be published in a follow up in Vol.1 i hope.
As soon as we have stuffed the new PCBs and tested them, i will also publish the changes on my MPP thread. Jacco, thanks for the enthusiatic words. From my point of view it´s a classic.
P.S. concerning the noise, when i compare balanced to unbalanced, balanced has a 3dB noise disadvantage provided we use the same amount of input devices, BUT it is much more robust in terms of hum pickup, so in a realistic setup it may be less noisy overall.
What is not shown is the servo. For more details i sugest you do youself a favour and get you a Linear Audio Vol.0. That bookzine has a lot of other interesting articles.
The servo shown there works only when you transfer balanced into unbalanced at the output. I designed a new servo that holds the DC offset to less then 1mV, single ended and differentially and it will be published in a follow up in Vol.1 i hope.
As soon as we have stuffed the new PCBs and tested them, i will also publish the changes on my MPP thread. Jacco, thanks for the enthusiatic words. From my point of view it´s a classic.
P.S. concerning the noise, when i compare balanced to unbalanced, balanced has a 3dB noise disadvantage provided we use the same amount of input devices, BUT it is much more robust in terms of hum pickup, so in a realistic setup it may be less noisy overall.
Attachments
Joachim
Tank you for the schematics.
I regard to Linear Audio I can’t think of a better present for myself for Christmas just ordered and now I have to sit by the door.
Not that it will do any good as our Postman waits for everyone to go out before making a delivery
Tank you
I just had a quick look at the schematics have you tried THAT 1646 as balanced line driver
I will start to use them in the next couple of weeks but from specs look like the OPA1632 may be a better choice
So tanks for that pointer as well
Irakli
Tanks for the schematics
Jacco tanks for the link worked mighty well
AL
Tank you for the schematics.
I regard to Linear Audio I can’t think of a better present for myself for Christmas just ordered and now I have to sit by the door.
Not that it will do any good as our Postman waits for everyone to go out before making a delivery
Tank you
I just had a quick look at the schematics have you tried THAT 1646 as balanced line driver
I will start to use them in the next couple of weeks but from specs look like the OPA1632 may be a better choice
So tanks for that pointer as well
Irakli
Tanks for the schematics
Jacco tanks for the link worked mighty well
AL
...and remember to point out that F9 and F10 are BF246A, correct?
THAT1646 is single ended output.
I'm running "His Masters Noise" -- and it is sweet!
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