[plakat]

XL4 is *much* more robust than those flimsy 2,5mm TRRS connectors... and there's absolutely no reason to use 2,5mm jacks in a desktop device.
 
If you intend to rewire headphones for balanced I'd suggest to standardize on XL4 termination, creating adapters for other cases (single ended, dual-XLR, maybe 2,5mm TRRS etc.). But driving a low-impedance, efficient headphone like the TH-X00 balanced won't buy you anything except some time with a soldering iron and the satisfaction of modifying them yourselves...

 

[Villy]

...driving a low-impedance, efficient headphone like the TH-X00 balanced won't buy you anything...

 
I tend to disagree. It is only my humble take on it based on my own modding experience, but at Fostex apparently they also believe there is something to be gained by going balanced considering that the A4BL was created specifically for 900 MKII.

 

[plakat]

   
I tend to disagree. It is only my humble take on it based on my own modding experience, but at Fostex apparently they also believe there is something to be gained by going balanced considering that the A4BL was created specifically for 900 MKII.

To me its in most cases an unwarranted expense (not the modification of a headphone, which can be a fun project in itself, but the additional electronics of a balanced amp). There are statements by people like someone at Benchmark (I think their technical chief architect or something like that) or Rob Watts of Chord speaking up for single-ended amp designs. I don't know how your level of knowledge on electronics design is, so I don't want to repeat potentially obvious points you already know anyway.
 
Overall I think offering balanced amps is more of giving customers what they call for (much like DSD) than offering an alternative that in most cases is better than single-ended (which balanced is not). The A4BL is still within power territory of a single-ended design, so not even the 'enormous power' argument counts in this case.
 
I don't think the A4BL was targeting the TH900mk2 but the TH610 (which will have removable cables as well). Which leads me to the conclusion that there might be something like an A8BL coming...

 

[Villy]

I don't want to engage in what Fostex meant or didn't mean by it, but they debuted 900 MKII with a optional balanced cable and A4BL together at NAMM 2016 and that to me says a lot (and not just to me really). While 610 is still just a teaser. 

 

[plakat]

I don't want to engage in what Fostex meant or didn't mean by it, but they debuted 900 MKII with a optional balanced cable and A4BL together at NAMM 2016 and that to me says a lot (and not just to me really). While 610 is still just a teaser. 

... Which was used in the background of the first photos of the A4BL.
I think they'll keep the two model setup just like with A4/TH600 and A8/TH900, would be very surprising to see the A4BL replace the A8. But never mind, they won't deny selling a A4 to pair with a TH900 of course, and I'm sure the combination will work just fine.

 

[Jethrosang]

Well, most IEMs are terminated in 2.5mm or 3.5mm balanced, so adding another output for this would be nice.
 
And I guess the thing about balanced output is down to the architect of the circuits, they might emphasise the performance of the balanced output, or just add it for the sake of having it. I think in Fostex case, even if they only have 1 dac, their amp is balanced out (I think it is true balanced, not just the matter of rewiring it). 

 

[Villy]

... Which was used in the background of the first photos of the A4BL...

 
Fostex at NAMM 2016

 

[plakat]

Fostex at NAMM 2016

And long before that:
http://www.head-fi.org/t/792916/fostex-hp-a4bl-the-a4-with-balanced-output

 

[ptolemy2k6]

How would one introduce balanced source to utilize balanced out? especially from usb out?

 

[Villy]

  How would one introduce balanced source to utilize balanced out? especially from usb out?

 
I don't quite understand the question, 'introduce balanced source' in what sense? Do you mean how will the data stream coming from the USB will find its way thru the components and end up being balanced signal into the headphones, is that it?

 

[ptolemy2k6]

   
I don't quite understand the question, 'introduce balanced source' in what sense? Do you mean how will the data stream coming from the USB will find its way thru the components and end up being balanced signal into the headphones, is that it?

hi
 
no. i meant. how would one get balanced input in order to use balanced out. i assume that if you use usb or rca or toslink in, it's not in balanced form?

 

[Villy]

OK, it seems you are looking for an overview of the process and I'll give it a try. In fact since I'm not an engineer my overview may actually come to be quite understandable 

 
 
So the data comes from the music player (computer, CD, digital media player, etc.) into the DAC as a digital stream (the computer bits you know, 1s and 0s like in 110001101). The DAC then utilizes a computing type of chip that is specifically programmed to recognize and convert the digital stream into analog audio signal. That analog signal from the converter chip then is passed to the DACs circuitry which in fully balanced DACs has physically separate paths for the RCAs and the XLRs on its way out. The signal going thru and out from the XLR side of the circuitry is different in many ways, from being fully isolated from ground interference/noise to being more twice as powerful. The amplifier on the receiving end must also have fully balanced design like the DAC to take advantage of the signal. And finally the balanced signal must be passed from the amplifier to the headphones thru a balanced output, where each channel has its own separate wires, 2 of them, one carrying '+' and carrying '-' signal, and none of the wires is shared with the other channel. In standard-ended output, the two channels have separate '+' signal coming to them and they share a common ground ('-') wire. 
 
In a single unit design such as HP-4ABL, both the DAC and Amp circuitry share the same box and signal transfer from to other happens inside. This design has the advantage of eliminating some conversion steps. On the downside, in integrated devices corners are usually cut to make the box affordable, otherwise it would be no less expensive than getting two separate units (like Oppo HA-1 and similar combo units).
 
Hope that makes any sense.

 

[ptolemy2k6]

  OK, it seems you are looking for an overview of the process and I'll give it a try. In fact since I'm not an engineer my overview may actually come to be quite understandable 

 
 
So the data comes from the music player (computer, CD, digital media player, etc.) into the DAC as a digital stream (the computer bits you know, 1s and 0s like in 110001101). The DAC then utilizes a computing type of chip that is specifically programmed to recognize and convert the digital stream into analog audio signal. That analog signal from the converter chip then is passed to the DACs circuitry which in fully balanced DACs has physically separate paths for the RCAs and the XLRs on its way out. The signal going thru and out from the XLR side of the circuitry is different in many ways, from being fully isolated from ground interference/noise to being more twice as powerful. The amplifier on the receiving end must also have fully balanced design like the DAC to take advantage of the signal. And finally the balanced signal must be passed from the amplifier to the headphones thru a balanced output, where each channel has its own separate wires, 2 of them, one carrying '+' and carrying '-' signal, and none of the wires is shared with the other channel. In standard-ended output, the two channels have separate '+' signal coming to them and they share a common ground ('-') wire. 
 
In a single unit design such as HP-4ABL, both the DAC and Amp circuitry share the same box and signal transfer from to other happens inside. This design has the advantage of eliminating some conversion steps. On the downside, in integrated devices corners are usually cut to make the box affordable, otherwise it would be no less expensive than getting two separate units (like Oppo HA-1 and similar combo units).
 
Hope that makes any sense.

hi
 
thanks for the detailed explanation but alas it's lost on me hehe. my q i think was simpler: if i connect usb out to computer and plugin into balanced port, instead of 1/4", will I get a balanced connection (lcd-3 have both balanced and 1/4" connection, that's why I am asking).
 
thank yiou

 

[Villy]

If you connect your computer, or whatever digital device that will play the music, to HP-4ABL, then you connect your headphones to the balanced headphone output, the XLR4 output, and the headphones' cable is truly balanced (that is, the cable has 4 separate wires, 2 per channel, and not a standard 3-wire cable that has been terminated with XLR), then yes your headphones will receive fully balanced signal.
 
I think we got it covered this time, right?

 

[ptolemy2k6]

you nailed it. thank you!