What a Balance Preamplifier Should Be Like?

[Fosi Audio]

This is another thread to make Fosi Audio closer to users. We always look forward to co-creating amazing audio gear with audiophiles. We have received a lot of advice that we should incorporate balance input/output to an amp or preamp. Our team is now developing a balance preamp and here is a concept design of it. We hope to receive some valuable advice and feedback from you again. Thanks in advance!

 

[SSS]

Question is whether the balanced type of amplifier is from input to output? Or is it just only balanced input converted to non-balanced amplifier and then the single ended output is converted to a balanced output. If the second is thought then the concept is worthless to me.

 

[Talisman]

This is another thread to make Fosi Audio closer to users. We always look forward to co-creating amazing audio gear with audiophiles. We have received a lot of advice that we should incorporate balance input/output to an amp or preamp. Our team is now developing a balance preamp and here is a concept design of it. We hope to receive some valuable advice and feedback from you again. Thanks in advance!

View attachment 308302

Serve what everyone is looking for and nobody wants to dare. Sub output with high pass filter for the speaker outputs, possibly with adjustable frequency. we all want to manage the subwoofer by splitting the frequencies, but nobody seems to care

 

[MCH]

I don't think the output selector is necessary, but a bigger volume knob, YES!

 

[JayGilb]

I don't think the output selector is necessary, but a bigger volume knob, YES!

Yes, add additional circuitry to make it capable of driving both sets of outputs simultaneously.

 

[restorer-john]

I like the concept. But you have a DAC in here clearly. As long as it is reasonably SOTA, you have a winner in my opinion. I agree with @MCH scrap the output selector unless you want to deliberately send signals to output A or B.

 

[Fosi Audio]

Question is whether the balanced type of amplifier is from input to output? Or is it just only balanced input converted to non-balanced amplifier and then the single ended output is converted to a balanced output. If the second is thought then the concept is worthless to me.

It should be balanced input to balanced output

 

[TonyJZX]

I don't think the output selector is necessary, but a bigger volume knob, YES!

yeah just have both outputs active all the time

i have to ask... why IEC? since we are talking low voltage why not a simple ext. psu?

also at this point everything gets harder...

we would like a basic remote... ie. vol. mute and input switch

while i would love it if it has an analog cutoff for sub out and mains, this is going to be hard

also maybe BT? I dont care for it but it sells units... and yes for me I dont want DACs but the market is the market

ALSO why do these units dont seem to have much in the way of a "company design language"? i think SMSL sort of has a design language

we know icons like McIntosh does. Why does this look so different to every other Fosi design?

 

[Sokel]

It should be balanced input to balanced output

Best would be balanced to everything and unbalanced to everything with decent noise and distortion.
This way we will have another one to suggest to people who search how to mix and match such I/O,every week there's another thread about it.

 

[Gorgonzola]

I've had a couple of preamps that provided balanced output but only if the input was balanced. I've had at least one the converted single-end input immediately to balanced & differential and processed the signal in fully differential mode thru to output -- this is very preferable IMO.

My current preamp, 25+ year old, tube preamp, processes balanced signals fully differentially but doesn't do the SE-to-differential conversion unfortunately. I'm OK in that I get a balanced signal from my DAC.

 

[Zek]

It looks like the pre-amp contains a DAC, so why doesn't it have a USB input?

 

[Speedskater]

Question is whether the balanced type of amplifier is from input to output? Or is it just only balanced input converted to non-balanced amplifier and then the single ended output is converted to a balanced output. If the second is thought then the concept is worthless to me.

Balanced interconnect systems are great. All balance internal circuits are an expensive engineering challenge.

 

[RosalieTheDog]

Serve what everyone is looking for and nobody wants to dare. Sub output with high pass filter for the speaker outputs, possibly with adjustable frequency. we all want to manage the subwoofer by splitting the frequencies, but nobody seems to care

This would be a unique and very useful device.

As for the main question: XLR / RCA active at the same time; remote.

 

[Joe Smith]

Are you also planning a non-balanced preamp (with a remote) that's in the design language/look of the V3?

For me, personally, a "pure" preamp without BT or an internal DAC (something competitive with the Schiit Saga preamp) is of more interest.

For the balanced users, wouldn't you want a balanced pre to be both balanced in - balanced out?

 

[JustJones]

Something like the Benchmark LA4 but more affordable. The 12v trigger is nice about time more started adding these.

 

[Jimbob54]

If you're having a dac in there, not having usb input is a mistake in my opinion.

 

[Norcal]

Serve what everyone is looking for and nobody wants to dare. Sub output with high pass filter for the speaker outputs, possibly with adjustable frequency. we all want to manage the subwoofer by splitting the frequencies, but nobody seems to care

yes, this is key...

 

[Hugo9000]

@Fosi Audio Thanks for seeking feedback on your products, and for sending gear to @amirm to test, it's much appreciated!

I have one request: could you please use green LEDs instead of the blue for power and the light around the volume control knob? I hate blue LEDs with a passion hahaha! If not green, then white or orange or practically any color except blue! Thanks!

I don't know why so many companies keep pushing hideous blue LEDs on us.

 

[SteveC]

Personally I like having a balance control (or dual volume controls). I seem to be pretty sensitive to that, though, and most folks don't seem to care much if it's off, so it might not be worth it to add that to the design.

 

[TonyJZX]

i see what's going on here

soon they will release a set of XLR monoblocks... seems about right?