OPPO 105 > XSP-1 gen 2 > UPA-1 = differential system?

[hcsunshine90]

I'm going to have my XSP-1 gen 2 in a few days here to go with my UPA-1's. was wondering if I ever add an OPPO 105 as a source, and used balanced connections throughout, would this be a fully differential system? when Lonnie talks in the video on the XSP-1 gen 2 page, and gets to the part where he says, "...the inverted channel gets turned back around so it's in phase again, and the two are added together. any noise that is picked up is now out of phase. and when you take something that's out of phase and add it to something that's in phase, the two cancel out to zero." I was wondering, if I used the configuration that I just listed, would I get the benefits of noise being removed from my system like Lonnie is talking about? the amp they have in the video is the XPA-1 gen 2 which is dual differential. I notice my UPA-1's are dual differential too, if that helps. thanks, john.

[Dark Ranger]

The descriptors can be a bit confusing. The XPA-1 Gen 2 actually uses a quad differential topology rather than dual-differential. In Emotiva's nomenclature, quad-differential is the indicator for "fully balanced."

Here is the current lineup of fully balanced (quad differential) amplifiers from Emotiva:

XPR-1
XPA-1 Gen 1/Gen 2
XPA-1L

So while the UPA-1 is not a "fully balanced" amplifier, it can certainly benefit from the noise reduction inherent with a balanced signal path and XLR cables. IMO, it's certainly something I'd try in your situation.

I used a XPA-200 amplifier paired with a XDA-2 in my main system for 13 months. The XPA-200 has a dual differential topology (not fully balanced) whereas the XDA-2 is fully balanced (e.g. Differential Reference). The two components were connected via XLR cables. The combination worked beautifully. I had zero noise issues to speak of (and I know for a fact there are noise issues in my room because I can pick up noise on some RCA/unbalanced cables).

You may not have any noise issues, so using either balanced or unbalanced connections may yield an inaudible difference.

[hcsunshine90]

so, if I can benefit from running balanced cables from the XSP-1 gen 2 to the UPA-1's, but not as much benefit as if the UPA-1's were quad differential amps, what do I get? some of the noise blocked out instead of all of the noise blocked out? or something like that...?

[garbulky]

Jun 7, 2014 21:43:35 GMT -5 hcsunshine90 said:

so, if I can benefit from running balanced cables from the XSP-1 gen 2 to the UPA-1's, but not as much benefit as if the UPA-1's were quad differential amps, what do I get? some of the noise blocked out instead of all of the noise blocked out? or something like that...?

I may be wrong. But..
I believe you get a 3db boost in SNR ratings even without it being fully balanced.
Also of interest, some DAC's XLR outputs simply sound better/different. Not because of it being balanced. But because it just does due to the design.
I believe some RCA outputs are conversions of the XLR output so there's that additional step. Not sure if it makes any difference or not but there it is.

I hooked up my HD600's direct to my XDA-1's XLR outputs and also compared it to the RCA outputs. The two sounded different and I felt the XLR may have sounded better. But since the XDA-1 was acting as a headphone amp on a demanding impedance that may simply be the power on tap for these two connections rather than actual sound quality difference.

But more importantly. XLR cables are actually quite cheap. They ARE the technically superior method to hook things up. If you can afford it there's no reason not to imo.
For instance these are 5 bucks. (I have them). They feel pretty solid. They are thick. A bit tight. And have no inherent noise to them.
www.monoprice.com/Product?c_id=115&cp_id=11509&cs_id=1150902&p_id=4750&seq=1&format=2

[hcsunshine90]

good to know about the 3db boost in SNR, thanks for that. just wondering now about the noise cancelling aspect or however you say w/ the XSP-1 gen 2 going to the UPA-1's. will noise be kept away using balanced cables? or maybe not because the UPA-1 is not quad differential. just trying to figure this out. thanks (and what  do i get with a quad differential amp that i don't get with a dual differential amp ?)

[creimes]

Jun 8, 2014 9:55:40 GMT -5 hcsunshine90 said:

good to know about the 3db boost in SNR, thanks for that. just wondering now about the noise cancelling aspect or however you say w/ the XSP-1 gen 2 going to the UPA-1's. will noise be kept away using balanced cables? or maybe not because the UPA-1 is not quad differential. just trying to figure this out. thanks (and what  do i get with a quad differential amp that i don't get with a dual differential amp ?)

Balanced cables are best for rejecting noise if there is any, that's why they use XLR cables in the recording industry and at concerts for long runs and such,the longer the run the more chance of picking up noise. If you have the equipment with balanced connections then I say use it and you don't need to spend a fortune on cables, Monoprice or Emotiva cables are great and even your local guitar/music shop sell XLR cables in many different lengths and that's where I have purchased mine, my philosophy is if they are good enough to use for recording the audio they are good enough to play it back as well

I have owned UPA-1's and XPA-1L's and hopefully soon will be adding three XPA-1L's again to my system and as far as fully balanced differential equipment maybe some can tell a difference but I could not so I wouldn't stress about it all that much. The UPA-1's are ones of the best value's in audio amplification IMO.

Oh and the Fully balanced from input to output differential circuitry of the XSP-1, XPR-1, XPA-1, DC-1 etc etc is for lower distortion and such if I remember correctly and IMO all the Emotiva gear I have owned sounds great

Chad

[Dark Ranger]

Jun 7, 2014 21:43:35 GMT -5 hcsunshine90 said:

so, if I can benefit from running balanced cables from the XSP-1 gen 2 to the UPA-1's, but not as much benefit as if the UPA-1's were quad differential amps, what do I get? some of the noise blocked out instead of all of the noise blocked out? or something like that...?

Jun 8, 2014 9:55:40 GMT -5 hcsunshine90 said:

good to know about the 3db boost in SNR, thanks for that. just wondering now about the noise cancelling aspect or however you say w/ the XSP-1 gen 2 going to the UPA-1's. will noise be kept away using balanced cables? or maybe not because the UPA-1 is not quad differential. just trying to figure this out. thanks (and what  do i get with a quad differential amp that i don't get with a dual differential amp ?)

To be honest with you, I'm not entirely sure on the technical benefits from Emotiva's Differential Reference design, aka quad differential. I seem to recall something about lower distortion figures, but don't quote me on that just yet. I could have sworn there was an explanation from Lonnie around here somewhere. Alas, my forum searching has proved unfruitful so far. Hmm... I need to call and talk to Lonnie about it, maybe this week or next.

Even without a fully balanced system, you can still benefit from common-mode noise rejection by using balanced cables (XLR). Back when I worked in the live audio environment (concerts, etc.), we used XLR cables 98% of the time. Used 'em for microphones, direct boxes, patch cables, the lot. Many of our cable runs ranged between 15 and 75 feet in length. Even though most of that equipment wasn't "fully balanced," the noise rejection was excellent. I hated using the occasional single-ended RCA or mono 1/4" connections around some equipment because they picked up a lot of the EMI running around on stage. Luckily, the vast majority of home systems have nowhere near that level of interference and noise.

My point is that, in your system, you don't need fully balanced amplifiers to benefit from simple noise reduction. You can run an easy test by powering up your system, but don't play any music. Put your ear up to the speakers and listen for noise (usually shows up as buzzing, ringing, or humming). Don't worry about hiss, that's normal. If you have noise, try the balanced cables instead (remember to power off your equipment first before changing cables). Power up and listen again. If it went away, then the noise rejection properties of balanced connections are working for you. If you still hear buzzing, humming, etc., then the issue is something else not directly fixable with balanced connections. We're talking stuff like ground loops or DC in the line, both of which require further troubleshooting.

Honestly, I wouldn't worry too much about using balanced versus unbalanced in a home environment.

[KeithL]

All else being equal... blah... blah... blah... 

* A balanced connection can be quieter - because any noise picked up equally in both wires cancels out.

* A differential circuit design can have lower distortion - because any distortion produced equally by both (identical) modules or channels cancels out.
(Beyond that, since this cancellation usually favors certain harmonics, the overall proportion of the various harmonics will be different as well.)

However, "all else" is never "exactly equal" anyway - if the device is balanced, you'll need an extra stage to convert unbalanced inputs to balanced; if it's unbalanced, then you'll need an extra stage to convert in that direction - and you'll never know if the difference you're hearing is simply that extra stage. For example, if you connect an unbalanced input to a fully differential amplifier, you might end up with lower distortion (because the amp itself is differential), or you might end up with higher distortion (because the unbalanced-to-balanced converter section adds a tiny bit of distortion itself). This is why it's not uncommon for the balanced and unbalanced inputs on a given device to sound slightly different (and either could be the better one).

I recall a "funny" review about an amplifier modification (on a Dynaco St400 - if anyone remembers those). The modification added a switch that could be used to bypass one of the gain stages - based on the premise that every gain stage makes distortion so, if you didn't need the gain, bypassing that stage would lower your distortion. To make a long story short, it turned out that the contact resistance on the switch itself introduced MORE distortion than the stage it bypassed... so the distortion was actually lower when the signal went through the transistor instead of the switch...

The more accurate way of saying things is that a differential design offers certain engineering advantages which, if properly taken advantage of, can allow you to design an amplifier with lower distortion (which might be audible as better sound). All the stuff about "dual differential" and "quad differential" is circuit details about how exactly everything is connected together... and our quad-differential circuitry offers a few more benefits than doing it some other ways. However, in the end, you should always judge an amplifier on the results rather than the means (using a quad differential circuit is no guarantee of low distortion or good sound - it just helps make it easier to get there).

And a balanced connection is only SPECIFICALLY going to sound better if you are having trouble with noise being picked up on the connection - in which case that noise should be reduced quite a bit. Otherwise, which will sound better will depend on the actual circuitry that was used on the equipment at either end of the connection. (In most cases you won't necessarily hear a difference at all.)

Incidentally, the "3 dB benefit of balanced connections" - above and beyond cancellation of noise picked up in the cable - is theoretical. (ASSUMING that the dominant noise was from the output stage of the source device and the input stage of the destination device, and ASSUMING that the balanced circuitry didn't add any noise of its own, the signal would be doubled - because you're adding two equal and out-of-phase signals - while the noise, being random, would average instead - so the ratio between them would improve a tiny bit. However, those assumptions aren't always true.) With most amplifiers, the overall S/N depends on all sorts of things, and they may or may not be a few dB quieter when you use one input or the other... Considering how quiet most amplifiers are these days, and the fact that 3 dB is barely audible, I wouldn't worry too much about it.

Jun 9, 2014 0:37:47 GMT -5 Dark Ranger said:

Jun 7, 2014 21:43:35 GMT -5 hcsunshine90 said:

so, if I can benefit from running balanced cables from the XSP-1 gen 2 to the UPA-1's, but not as much benefit as if the UPA-1's were quad differential amps, what do I get? some of the noise blocked out instead of all of the noise blocked out? or something like that...?

Jun 8, 2014 9:55:40 GMT -5 hcsunshine90 said:

good to know about the 3db boost in SNR, thanks for that. just wondering now about the noise cancelling aspect or however you say w/ the XSP-1 gen 2 going to the UPA-1's. will noise be kept away using balanced cables? or maybe not because the UPA-1 is not quad differential. just trying to figure this out. thanks (and what  do i get with a quad differential amp that i don't get with a dual differential amp ?)

To be honest with you, I'm not entirely sure on the technical benefits from Emotiva's Differential Reference design, aka quad differential. I seem to recall something about lower distortion figures, but don't quote me on that just yet. I could have sworn there was an explanation from Lonnie around here somewhere. Alas, my forum searching has proved unfruitful so far. Hmm... I need to call and talk to Lonnie about it, maybe this week or next.

Even without a fully balanced system, you can still benefit from common-mode noise rejection by using balanced cables (XLR). Back when I worked in the live audio environment (concerts, etc.), we used XLR cables 98% of the time. Used 'em for microphones, direct boxes, patch cables, the lot. Many of our cable runs ranged between 15 and 75 feet in length. Even though most of that equipment wasn't "fully balanced," the noise rejection was excellent. I hated using the occasional single-ended RCA or mono 1/4" connections around some equipment because they picked up a lot of the EMI running around on stage. Luckily, the vast majority of home systems have nowhere near that level of interference and noise.

My point is that, in your system, you don't need fully balanced amplifiers to benefit from simple noise reduction. You can run an easy test by powering up your system, but don't play any music. Put your ear up to the speakers and listen for noise (usually shows up as buzzing, ringing, or humming). Don't worry about hiss, that's normal. If you have noise, try the balanced cables instead (remember to power off your equipment first before changing cables). Power up and listen again. If it went away, then the noise rejection properties of balanced connections are working for you. If you still hear buzzing, humming, etc., then the issue is something else not directly fixable with balanced connections. We're talking stuff like ground loops or DC in the line, both of which require further troubleshooting.

Honestly, I wouldn't worry too much about using balanced versus unbalanced in a home environment.