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All things being equal and assuming no difference in length, is there a sonic benefit from using the XLR connections (say on the front three channels) verus the RCA? I always thought not, but then I can't reconcile the fact that I read that Balanced XLRs have lower noise than the RCA because balanced lines cancel noise picked up in the cables, and 6dB more volume.
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Adz -
Can anyone help me out here?
Thanks in advanceAdz -
99% of the time I'd say save your money or at the least put it elsewhere. You're likely to get better performance out of more expensive RCA's then same priced XLR's IMO.
Studies have been done that show little to no improvement using XLR. Most equipment allowing XLR connections aren't "true" balanced designs anyways which nulls any of XLR's bennefits.
So, if you have true balanced design equipement, you may have some bennefit from using XLR on already noisy runs. IMO your better off finding out where that noise is coming from and fixing that problem.JasonComment
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The way I've had it explained to me is a 500 dollar pair of rca's is comprable to a 150 dollar XLR. Not sure the truth on this.. like I said this is what I've been told by a nearby dealer. please correct me if I'm wrongComment
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I've tried XLR vs. RCA on some short runs and I could not perceive any difference in sound quality from one to the other. This was using a Denon DCD-1560 CD player, Anthem AVM 20, Levinson No. 23, and Ellis Audio 1801b speakers. The interconnect cables I used are "better" than those provided with most equipment if in no other measures than build quality, but certainly far, far from high-end cables. The speaker cables were just plain old 12 ga copper wire.There are some things which are impossible to know, but it is impossible to know which things these are. :scratchhead:
----JAFFE'S PRECEPTComment
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Balanced have the potential for lower noise, the benefit obviously depends on how much 'noise' there is in the environment. For HT there's usually not much noise
If the claim is that using balanced IC's will +6dB of additional sound pressure level that's just silly.
Read this link for more info about decibels
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-BressonComment
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Thanks guys! I take all your points - its what I thought for the most part.
Jason- I have a Bryston pre/pro and processor - both are fully differential balanced designs.
Thomas - to clarify the +6dBs is in the balanced output in the processor versus the unbalanced.AdzComment
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Originally posted by Adz
Yup Bryston's one of the ones that is :drool:JasonComment
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Adz,Originally posted by Adz
If memory serves, Bryston's preamplifiers such as BP-20 or 25 are not fully differential designs. This however does not make them bad. Although I never looked inside the processor, but I do not think it is fully differential either.
Bryston's pre-amplifier, such as BP-25 has a differential amp in the front that converts the signal to a single-ended type with balance/volume control followed which is referenced to ground. Then the signal gets to a single-ended to differential converter and the output is available in either a single-ended or balanced type.
It is a classic no-frills design.
Regards
VictorComment
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Victor,
That may be so with respect to the 1.7 (which is basically comprised of a BP25) but what about their SST amps? I'll ask Bryston directly to reply to your comment.
Thanks,AdzComment
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All I can say is that there was a very large difference :E with my set up when I switched to balanced connections. Other people noticed the difference as well. I have a krell showcase and bryston 4b-st and 5b-st. Going from rca to XLR was big in my setup. Just MY experince
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Comment
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Adz,Originally posted by Adz
Any power amplifier can be used in a differential mode, - all you need to do is to bridge 2 amps and you are done. This way ground is no longer in the picture. By definition, the differential mode of operation is such when the signal is referenced to its out-of-phase image. The bridging option does that.
However, one can also argue that a truly differential design is the one where the signal is kept in the differential mode by the virtue of the circuit topology. Bryston amps definitely do not qualify as per the latter definition with a possible exception of the 7B or 14B when operated in the parallel mode. Anyway, examples here might be the X-Amp design from Nelson Pass and Ampzilla by James Bongiorno. There are others, but they are rather rare.
The SST amplifier from Bryston is an extension of a successful older NRB line. It is not a major departure from the NRB but rather a modification. Bryston amplifier topology is fairly common classic complimentary design with an exception of the output stage. The output stage is very clever as it uses its own negative feedback and has a bit of voltage gain. It kind of goes against the textbook, but Bryston managed to get it to work, resulting in a stellar THD numbers.
Normally most of the distortion comes from the output transistors being driven close to its non-linear region by the power demands. However, in the case of all Bryston amplifiers the local feedback attempts to maintain linearity to a point even at high power demand. This approach certainly differentiates Bryston designs from anything else on the market place.
So, the SST design brings better power supply, more modern output transistors and most likely better wiring while maintaining the overall gain structure of the ST design and overall circuit topology concept of the NRB design. All in all it is a good amplifier.
Regards,
VictorComment
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Hi Victor --
Thanks for the feedback. All I can say is check out these links!!
AdzComment
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Adz,Originally posted by AdzHi Victor --
Thanks for the feedback. All I can say is check out these links!!
http://www.bryston.ca/newsletters/31_files/vol3is1.html
Yes, I am well aware of the articles in the links you provided. I personally do not advocate a fully balanced approach to audio. I hope you noticed that in my previous post I simply alluded to this fully differential approach as an alternative only and not a preferred method. The articles in your links are full of both useful technical data and shameless audiophile-type techno-bubble nonsense. Well, it is advertising after all.
A fully differential circuit achieves its noise reduction at the output across the load. It works well in theory if both halves are identical, which is impossible to achieve with discrete components, although you can come very close. Such circuit is only useful if the source is also fully differential to begin with, such as now nearly defunct phono-stylus or a microphone. Bryston articles do not tell you that little detail, although they do say that the Bryston mike pre-amp uses a fully differential topology. Naturally with a fully differential source there is no reason to worry about common mode signals.
Bryston, in its literature, chooses to emphasize the benefits of its approach while downplaying the choices taken by others. You can’t really fault them for that, - they want to sell you their equipment and so they want to praise the engineering choice they made.
I have no problem with Bryston’s approach to handling differential signals. I do however draw the line in calling Bryston’s topology a fully differential circuit, - it is not. Both approaches have their respected places under the sun.
... regardsComment
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Thanks Victor. It's a lot to absorb!
A person knowing that much about a Company's product, either has worked (or should be working) for that company. My guess is the former. I'll switch from RCA to XLR and back and forth and judge for myself.AdzComment
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ADZ says,
Well, you don't really need to ask them, since they provide their schematics for download, you can easily see that Victor is quite correct. With respect to their amplifiers, the schematic clearly shows Bryston uses a standard differential amplifier in the front end and simply switches between single ended and balanced using the same differential amp.That may be so with respect to the 1.7 (which is basically comprised of a BP25) but what about their SST amps? I'll ask Bryston directly to reply to your comment.
I'm going to give my vote to using balanced connections if they're provided. It just seems to be the most reasonable method of transmitting a signal on a high impedance interface.
For anyone who needs a refresher, very basically, balanced outputs use three wires instead of the two used in unbalanced connections (or single ended as it's known). Generally they use an XLR connector.
One of the three wires is signal ground, the same as you're use to in RCA single ended cables.
The other two wires carry the audio signal, each being 180 degrees out of phase from each other, like a mirror image. These two signals usually come from matched op amps or a differential amplifier, one amp which is inverting and one which is a non-inverting amp. You can call these two signals plus and minus.
When the plus and minus signals arrive at the receiving end they travel into a difference amplifier which obviously only allows signals that are "different" to pass.
The 'audio signal' is completely different because it's out of phase and therefore passes easily. Now here's the beauty of this arrangement. If there is noise picked up on this balanced XLR cable in its travel from pre-amp output to amplifier input, then that noise is picked up equally on both the 'plus' and 'minus' wires. Because these two signals are the 'same' they are rejected by the difference amp. This is known as common-mode rejection, so, any noise is cancelled and any audio signal is freely passed.
In a single ended arrangement, noise is picked up on the single audio wire with reference to ground and is then amplified. Yuk.
Generally, balanced connections are a must in a recording studio where there are miles of cables criss-crossing each other. It would be a disaster to use single ended in these applications. In any case, balanced connections are a recipe to have a quieter system.
Balanced connections certainly provide superior isolation against external interference and reject any noise that may want to jump a ride on the cable from any number of sources. Radio Frequency (RF), noise from dimmers or fluorescent lighting, AM/FM radio transmissions, mutual inductance from proximity cabling can easily cause interference with your signal. A wire connected to a high impedance input is simply a great antenna......
Obviously this sort of arrangement has to be well done with matching input impedances and high quality differential amplifiers and precision resistors for matching the two channels because there is a lot of chance for distortion from a difference amp. If one channel handles the signal differently than the other, distortion will be introduced into the resultant output signal. But, this is a fairly well understood method of transmission. Today, usually single chip differential transmitter/receivers take care of all this rather nicely. There's little need to add extra circuitry in excess of the single ended method. The positive channel of the difference amp is simply used for the single ended driver/receiver, as you can see if you downloaded the schematic I referenced.
I just feel the advantages of balanced connections beat single ended, hands down.
- The connector is clearly superior. You can doll up an RCA connector with spinning barrels and split pins, but it's still a crappy connector.
- The ability to affect independence of the chassis ground from the signal ground.
- Balanced connections run higher levels over the line.
- You don't complete your circuit over a shield.
- You have the ability to run long lengths to your power amplifiers allowing them to be placed close to your speakers to accommodate short speaker wires.
The key phrase here is 'no difference in length'........ For short runs, it will likely matter not. For longer runs, there will usually be a difference because of noise floor..All things being equal and assuming no difference in length, is there a sonic benefit from using the XLR connections
Anyway, my vote goes to balanced. I have a Bryston processor and three Bryston amplifers and I certainly take advantage of the fact that they have provided balanced connections...... :W
brucekComment
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Thanks Bruce. I'll be sure to study that schematic! 8O 8O 8O
Great to hear from you !! Been wondering where you have been. Check out my recent thread on a problem with one of my dedicated outlets.
I ordered Balanced connections and I'll swap back and forth to see if I hear a difference. Tanner thinks it will be noticably different. Love my Bryston equipment.AdzComment
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Great to hear from you bruce! Hope all is well and thanks for the input!jpiscitello@ameritech.netComment
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Adz,Originally posted by Adz
I know that it is often the case where one wants to hear discernable differences only because the option to try different things is available. After all the Parkinson’s Law says that if you give organization resources it will find the way to use them.
Anyway, in this case since both balanced and unbalanced connectors are available, one would like to think that the balanced connector, which is clear superior, will yield a discernibly better sound. I hate to disappoint you but this will never happen in reality.
I know that Mr. Tanner of Bryston would like you to think otherwise but unless you live in a very electromagnetically active environment or use at least 100 meters or more of low grade gauge 30 wire you will never be able to hear any differences between balanced and unbalanced connections. People that claim to hear those differences normally set-up the test erroneously.
Generally humans hear differences in sound as a result of changes in frequency response or volume level. In fact a 0.1 dB change in level will be noticeable and may account for a preference to a particular sound. Well, interconnects should not introduce any frequency response or level variations unless you are using a wire from Transparent Cable company, etc. with their infamous “networks”. If you use Belden wire then you are in good shape.
If you hear noise coming from your hi-fi rig in a common house environment then something is definitely wrong and use of balanced interconnects may band-aid the problem but it is hardly a good solution. Personally I would also give my vote for the balanced connectors, not because I can hear a better sound as a result, but because it is a better engineering solution and that makes me feel all warm and fuzzy inside.
By the way the balanced connector itself is only a part of the picture. The differential amplifier that follows is the important thing. Look at Bryston’s implementation of the diff-amp. It is a text-book solution. The question is, - is this a good solution? Bryston circuit topology is published.
The op-amp used is a classic discrete fully complementary circuit. It is a bare-bones circuit also, as it has absolutely nothing to minimize any adverse effects inherent in amplifier design. None-the-less it works very well in most applications such as filtering application or as a gain block.
Is it a good candidate for a differential amplifier? My take on it that it is not. That is to say I would not use it in this application. Bryston would naturally disagree and they have all the right to do so. What I am saying is not a criticism but rather an observation. The circuit after all works well enough judging from the THD numbers that Bryston publishes.
The reason I would not use it as a differential amplifier, because the circuit is bound to have high input bias currents and its topology is not conducive to a high common mode rejection. Bryston naturally matches the resistors used in the differential amplifier set-up, but in doing so they neglect the fact the impedances into positive and negative op-amp inputs are not the same. So, even if the input resistors are matched to 0.1% still I would be very surprised if the common mode rejection ratio would ever rich even 40 dB at low frequencies, let along at 20 kHz. I am not sure how much noise does this amplifier actually reject.
In any event there are better solutions available and they are not expensive.
…regardsComment
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Thanks Victor.Anyway, in this case since both balanced and unbalanced connectors are available, one would like to think that the balanced connector, which is clear superior, will yield a discernibly better sound. I hate to disappoint you but this will never happen in reality.
I know that Mr. Tanner of Bryston would like you to think otherwise but unless you live in a very electromagnetically active environment or use at least 100 meters or more of low grade gauge 30 wire you will never be able to hear any differences between balanced and unbalanced connections. People that claim to hear those differences normally set-up the test erroneously.
I'm not sure why Bryston would care what IC I choose to use, but you'll certainly be the first I report back to which will be based on my perception, not necessarily science.AdzComment
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brucek, that was simply the best explanation of what "balanced" topology is all about that I have ever read. Now, my questions are as follows:
1) Would it make sense to have both balanced and unbalanced channels in a multi-channel home theater set-up that is also used for stereo music listening? In other words, use front left and right balanced channels for critical listening (i.e., stereo music) but then use these balanced front L and R channels along with single-ended mode center and surrounds for home theater. It is my understanding that very few of the multi-channel home theater processors and amps available today offer balanced modes on all channels, so aside from potentially saving money on interconnects this might be my only practical option.
2) What other multi-channel pre-amps/processors and amplifiers offer balanced technology? I believe some McIntosh amplifiers have this capability, but I think it is only their stereo models. I don't believe that Anthem's D-1 processor or their line of Signature amps offer balanced modes of operation, whether in stereo or multi-channel use, correct?
Thanks again for making a complicated subject easier to understand!Comment
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Originally posted by RU Geekman
B&K, and Some Adcom at least they use toComment
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RU Geekman,Would it make sense to have both balanced and unbalanced channels in a multi-channel home theater set-up that is also used for stereo music listening?
Well, as I was saying in my last post (and also in Victors post) you're not likely to hear any sonic differences between the single ended and balanced connections unless you're running long lengths or you live in a noisy environment. There is also a good chance of distortion if the balanced differential circuitry isn't executed well. It's only an advantage if it's done well.
In an inexpensive processor you may find even though they provide some or all balanced connections, that it may be more for bragging rights and sales than trying to providing sonic quality.
If you're looking to save money, don't look for balanced connections....
brucekComment
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I know that Anthem AVM20/30 have XLR jacks and so do several models of their amps. I do not know if they are actually balanced circuit topology.There are some things which are impossible to know, but it is impossible to know which things these are. :scratchhead:
----JAFFE'S PRECEPTComment
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Okay, my balanced ICs arrived and I switched back and forth between balanced and unbalanced across the front three (Bryston 1.7 out to a Bryston 6B SST). I went back and forth on a couple of my favorite CDs and DVDs, and I'll say that for the most part the highs and mids sounded indistinguishable, but it was in the bass that my wife (yes my wife as my witness since the cables were demos) and I both agreed was very noticeably punchier /tighter. Not sure if that's the theoretically correct answer, but that was our observation and she thinks I'm basically a nutjob with all this.AdzComment
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Uh huh. I think MOST of our significant others would agree with her. :yesnod:Originally posted by Adz.
David - Trigger-happy HTGuide AdminComment
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Victor,
Thanks for your insightfull comments. I always learn something when you contribute to a discussion. Can you point me to examples of equipment with balanced circuitry that uses what you called, "better solutions available and they are not expensive."
Is there a way to identify these "better solutions" without a schematic? Something I could recognize/identify by looking at the PCB/wired connections?
Again, thanks for yours and brucek's contributionsBruceComment
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Bruce,Originally posted by Bruce
I do not normally use commercially built power amplifiers or pre-amplifiers, - so I am not a right person to recommend a commercially available design that uses a more advanced topology then Bryston in a given application. I built my own gear and, therefore, I have a freedom to choose circuits that are better suited to an application at hand.
With this in mind, when I said that better and less expensive solutions are available, I was actually thinking about the DIY approach. For a differential amplifier I would not consider a discrete circuit, - I would use an available monolithic op-amp like AD797 in a more advanced 2-op-amp differential circuit topology. I may also use a more specialized part like AD813 or even a special purpose differential driver of an AMP or SSM series of products from Analog Devices.
In any event Bryston’s approach to a differential amplifier is certainly inferior in terms of noise reduction to any of those products.
I am afraid you cannot determine which is a better differential driver just by looking at the circuit board. However, a presents of a low-noise op-amp is a good indication of a superior performance, - it will also be a less expensive implementation.
..regards
VictorComment
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Does anyone know if the Classe SSP-600 and CA-5200 are true balanced designs?Comment
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