I did a search and couldn't find a thread that identified which FW amps and which pre-amps can be built balanced, so I thought I'd start a thread and ask the question. I've inferred from some previous discussions that some FW amps can't be converted to balanced monoblocks.
Off the top of my head, I know the F4, BA-3, F5 can be built balanced.
Can the WHAMMY and Wayne's 2018 pre be balanced?
I've also seen references to "differential" or "fully differential" and I don't know what those are, so if those are further degrees of balanced operation it might be nice to identify which balanced designs allow for that kind or style of balanced operation.
Edits:
Adding Aleph J to the list of can-be.
Off the top of my head, I know the F4, BA-3, F5 can be built balanced.
Can the WHAMMY and Wayne's 2018 pre be balanced?
I've also seen references to "differential" or "fully differential" and I don't know what those are, so if those are further degrees of balanced operation it might be nice to identify which balanced designs allow for that kind or style of balanced operation.
Edits:
Adding Aleph J to the list of can-be.
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If you look in the Wayne’s pre thread or the comments in the diy store I am pretty sure someone has already built a balanced preamp using 2 boards.
Aleph J are balanced , Sony Vfet CSX is balanced if you do use low impedance source ( no need jfets buffer )
With the wide availability of low noise/high bandwidth DAC's, leveraging balanced interconnects is almost mandatory to get the full benefit of the DAC.
I'll likely never again use a single-ended Amp. You can hear the difference, even using my OPPO Sonica DAC directly XLR connected to an Aleph30.
I'll likely never again use a single-ended Amp. You can hear the difference, even using my OPPO Sonica DAC directly XLR connected to an Aleph30.
You can make a balanced amp out of any pair of channels that have
single ended inputs and outputs and a common ground - just drive them
with a balanced source. Works like glue...
Even with the J2 which is balanced input and single-ended output, just
ground the - inputs (pins 3) and drive the two + inputs (RCA or pins 2).
single ended inputs and outputs and a common ground - just drive them
with a balanced source. Works like glue...
Even with the J2 which is balanced input and single-ended output, just
ground the - inputs (pins 3) and drive the two + inputs (RCA or pins 2).
Same here....all this building never ends.....which is good! I think before I commit all my Semisouths I will wait for "official" release when there is plenty of info. For now I have a few schematics, 2 different sets of PCB so I will build one of those.
Russellc
You can make a balanced amp out of any pair of channels that have
single ended inputs and outputs and a common ground - just drive them
with a balanced source. Works like glue...
Even with the J2 which is balanced input and single-ended output, just
ground the - inputs (pins 3) and drive the two + inputs (RCA or pins 2).
Thanks for chiming in. I always love your comments because they usually have a lot to unpack and I always learn something.
I'm going to list off a couple conclusions I've tentatively reached and hope people will let me know if any of them are wrong.
- The list of FW amps that can be built balanced are those that are stereo with SE output and common ground. This does not rule out those listed on the FW products page as having P or PP output, as there exist balanced variants of the F4, F5, and F6. SE/P/PP may not be referring to the kind of single-ended output referred to here, then. I'm going to guess that all FW amps are the kind of single-ended output you're referring to here, which is in contrast to differential output like you might get with some headphone amps.
- The BBA-3 did not need to have the source input resistors combined to convert it to balanced operation, this was some kind of optimization.
- EUVL's F5X stuff wasn't necessary - the F5 could have been done up as a balanced amp as-is.
- The primary source of complexity in the balanced-or-not discussion comes from people wanting to be able to use both SE and balanced inputs on the same amp.
- Some resistors may need to be more tightly matched to get the + and - outputs on balanced monoblocks to match up, as in Aleph J illustrated build guide
- The WHAMMY is balanced as-is. I only mention this because this is my next build and I've just gone over the schematic to confirm that the out ground is shared, and I saw that someone else has already done this deep in the build thread.
- Google has informed me that I've used the term balanced in place of the more correct term of differential, and this is a common mixup. Practically, fully differential just means XLR from DAC to Pre to Amp with no summers and splitters in between that secretly convert the signal to single-ended and then back to differential, including the DAC's gain stage, though the DAC may use a splitter to generate differential output. Differential implies balanced. Balanced does not imply differential.
Do any of the FW amps satisfy the definition of non-differential balanced inputs with matching impedance on signal input and signal input ground?
Is impedance matching on signal input ground necessary or recommended when building a differential amp? I'm guessing no, based on what you've said.
I know zilch about this stuff so thanks for helping me wrap my head around it.