The SR71B, quad mono balanced . images pg 17 .Review pg 32, 34 . - Page 7

Quote:

Originally Posted by SHADYMILKMAN 

Hi Ray,

 

Is it going to be two knobs (additional size/weight) or 2 dials like whats on the shadow?

 

Thanks

It'll almost certainly be knobs, since the analog pots in question have a shaft that would be exceptionally difficult to control with a horizontal rocker like what is on the Shadow.

Quote:

Originally Posted by wolfen68 

Doesn't any digital source (such as H140 optical) also provide a signal that can be balanced?  I thought the "balanced" part was only on the analog side, after the digital signal is converted.

Quote:

Originally Posted by The Monkey 

So, with Ray's new amp, what would be the most noticeable sonic benefit using a true balanced source with balanced cans compared to a single-ended source with balanced cans?

Quote:

Originally Posted by thread 

Yep, here's the prototype AlgoRhythm from Cypher Labs as demo'd at CanJam. It is a licensed Apple device that is able to pull the digital stream from iDevices.

 

As far as I know, it outputs single ended only. No balanced output.

It seems to me that if you're getting a digital signal out of your DAP, and then converting that signal to a balanced analog signal at the DAC level, then going into a truly balanced amp like the SR71B or Protector, then out with a balanced cable configuration to a highly-resolving IEM like the JH-13, that there would be at least as much of a sonic benefit as a high-end balanced desktop rig, and that would be a worthy goal for anyone that wants to reach the pinnacle of portability.

Now I'm just speculating here, but if you could integrate a balanced type JH-3A DSP-controlled crossover amp into that system instead, you'd really have something to "write home" about! That would be the absolute pinnacle of portability, IMHO.

So what would have to improve to get to this theoretical level? The AlgoRhythm having balanced output, and the JH-3A having a balanced in/out, I suppose.

The Protector is not truly balanced at the source input. Based on Ray's post above, it sounds like the SR71b has multiple inputs - one for SE, another set for balanced. Haven't seen pics of the SR71b, so I am assuming.

Quote:

Originally Posted by jpelg 

The Protector is not truly balanced at the source input. Based on Ray's post above, it sounds like the SR71b has multiple inputs - one for SE, another set for balanced. Haven't seen pics of the SR71b, so I am assuming.

Hopefully, Ray will be good to us and brings one to display at the upcoming Charlotte, NC Can Fest...

I forgot about that limitation of the Protector and edited my post, thanks.
 

I do actually believe that balanced has just as profound (or moreso) an effect on IEMs as any lowish impedance headphone and in a portable mode it actually works quite well IMO, with great sound quality as given, but also due to CMMR the world of buzzing GSM towers and mobile phone pings ceases to be an issue. I have also tuned my home rig specifically for low gain/low noise balanced output and really do feel balanced output from dacs is the way to go, so it makes sense to continue the signal like this through the amp stage.

pretty much all modern dac chips have balanced output, most dont even have SE output anymore, so having a single ended system that maintains all the DNR of the dac output, requires another SE conversion stage and therefore more components in the signal path. on the other hand you can do balanced IV conversion and headphone amp in a single differential IV stage (with as little as 1 or 2 opamps) with only a small amount of gain, a buffer would only be needed for higher impedance cans.

now that this has balanced input it becomes more true, as the protector only floats ground and replaces with the inverse signal on the output, so isolation from/removal of the ground noise from before that is not possible.

and the tech marches onwards!! but yes, we do need more balanced portable sources......
 

Quote:

Originally Posted by grokit 

 

It seems to me that if you're getting a digital signal out of your DAP, and then converting that signal to a balanced analog signal at the DAC level, then going into a truly balanced amp like the SR71B or Protector, then out with a balanced cable configuration to a highly-resolving IEM like the JH-13, that there would be at least as much of a sonic benefit as a high-end balanced desktop rig, and that would be a worthy goal for anyone that wants to reach the pinnacle of portability.

 

Now I'm just speculating here, but if you could integrate a balanced type JH-3A DSP-controlled crossover amp into that system instead, you'd really have something to "write home" about! That would be the absolute pinnacle of portability, IMHO.

 

So what would have to improve to get to this theoretical level? The AlgoRhythm having balanced output, and the JH-3A having a balanced in/out, I suppose.

I think you are getting a bit mixed up here, the JH3A(and the JH1X IEMs) is a 6 channel DAC/DSP/amp/monitor system, if you wanted it to be balanced it would have to be a 12 channel unit and you would have to have a 12 wire cable and 12 terminal connection system, this just isnt going to happen any time soon; its possible, but very unlikely and the dac/dsp in the cyrus chip they use is not capable of multichannel differential conversion, it has balanced line out, but only in stereo. you couldnt run 2 in dual differential either. so the only way to do it would be to run 6 differential opamps with SE input/bal output like the OPA1632 or THS4150, DRV135 line driver etc, or perhaps you could use a second one and feed it an inverse phase digital signal, or invert the output of all 6 channels of the second chip........ one big mother of a battery!!! an army of IC regulators and a 12 channel pot (well really digital is the only way here IMO)

thought I would include this next bit to you in a spoiler thing, I havent used it in a post before, but thought this bit was continuing off topic too much for this thread, so this is for you specifically and isnt a spoiler typical

Well qusp as I said I was just speculating, but thank you for bringing that speculation back in line with reality!

BTW, what does the Canadian Mouse Mutant Repository have to do with this discussion ?

Sweet.  I'll finally be able to use the balanced output of my Apogee Mini-DAC.  iHP-132 -> Apogee Mini-DAC -> SR-71B -> custom molded UE-10 Pros.  That should be pretty solid.

-Jim

haha well actually its common mode noise rejection, why its not CMNR I dont know, I could be missing a word there, basically it means that any signal that is common to each +/- signal line (and in the same phase) ie interference or noise/distortion that is coupled to the signal, is added/summed together and cancelled out/removed. this is pretty much the center of why balanced audio transmission was invented; in order to allow long cable runs in studios and venues to be used without picking up a heap of interference along the way.

in our case this summing stage is either at the opamp stage, or at the headphone driver itself. having a stronger amount of swing is often a nice byproduct, but does not have to be the case.

tyhis is also why twisted pair cables are so common in audio and particularly balanced audio, with twisted pair, the interference equaly effects each phase, so the CMMR is more effective

The Protector I listened to was picking up interference.  I'm not sure if it was wifi, cell, etc., but it was that type of sound.  Of course, the Protector is not alone in this regard as I have heard interference on most, if not all, portable amps I have tried (including the Pico Amp/DAC this weekend).

yes, well the protector is vulnerable still, because it only converts to 'balanced' at the output opamp/section, so any noise that is coupled into the signal before that point will remain in the signal

So, provided that one's rig is balanced throughout, we should expect the SR71b not to suffer from such interference?  That would be nice if true.

yes, well there would still be a tiny amount remaining, but common mode noise rejection usually works in the order of -90db or so (I actually just plucked that number out of the air, but something like that and the exact amount varies with the design/chips) so a signal that is already comparatively weak like noise, reduced by that much is going to be effectively removed.

I would think that proximity of any amp to the energy field around the iPhone, particularly when the phone is communicating, could result in hearing noise interference. I would not expect even a balanced configuration to solve this problem. I'd instead suggest using a non-phone source, such as the iPod Classic or Nano, for a noise-free experience. Also keeping any cellphone some distance away (or off) during your listening session is probably a good idea. Just common sense, I'd think. *shrug*

why would phone interference not be treated as common mode noise? it would effect both phases equally and should be removed. this type of thing is exactly why balanced was invented. when out and about you cant really control what other people do with their GSM. what makes it any different to any other type of EMI/RFI interference? noise in the audio band, is noise in the audio band, the device doesnt know the difference AFAIK. CMMR will be more effective at some frequencies than others and this type of spec is usually mentioned, but the source is meaningless is it not?

I use my phone when working on totally unshielded balanced audio devices on the bench and cant say I have noticed any problem