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I have an Audio Research SP-8 tube preamp that I am happy with. It has only RCA connectors. Lately I have been considering buying a more powerful power amp some of which either have only XLR inputs or, according to reviews, sound better when connected with balanced connectors.
I believe I have seen XLR-to-RCA adapters with which connections could be made to my preamp, but I am wondering:
1.) Do balanced connectors always sound better than unbalanced ones?
2.) Why is that the case?
3.) For those in my situation, would I achieve better performance by using XLR-RCAs at one end and XLRs at the other or would this not yield any improvement?
In my setup, I used pre-to-power amp interconnects of ca. 12 feet. Would switching to XLRs negatively affect such a setup?
Thanks,
George Roland
Follow Ups:
You will gain no benefit using balanced cables from your single-ended preamp to your balanced amp. If the goal is to run an amp with only balanced inputs, or one that clearly sounds better from its balanced inputs, using your single-ended preamp, then RCA/XLR adapters will probably not help either.
Try Jensen or Lundahl input transformers at the amplifier input for single-ended to balanced conversion. Lundahl makes a transformer that plugs directly into your amp's XLR input, so no extra cable is needed. One caveat, this works best when running low output impedance into high input impedance. Jensen sells Jensen and K&K a Audio sells Lundahl.
The vast majority of power amplifiers that have both single ended and balanced inputs (and there aren't that many) just convert the signal coming into the XLR jacks into single ended with a relatively inexpensive circuit, so just make sure you know the topology of the amplifier. There is no benefit in going with an external transformer in this case, I think.I see no reason to mix and match, preamp and amplifier matching is critical to good sound, and XLR/RCA signal adaptors (without transformers) are a solution looking for a problem.
As you said, the OP should stick with single ended circuitry/connectors. If he's married to the preamp and doesn't have ridiculous cable lengths.
More important is the input impedance of the power amplifier, higher is better (over say 30k). No use getting, say, a Krell or Rowland power amp which was designed to be used with a solid state balanced preamp, hooking it up to the tubed ARC and expecting outstanding sound.
Edits: 01/22/15
They just came out with a $3500 preamp - RCA only.
Yeah, lots of people in the market want unbalanced connectors but Mark says there's no difference in his experience so the new pre is RCA only.
Good for Mark.
"We are all in God's hands... and God is a malign thug."
-Mark Twain
George, If you plan to keep your preamp don't worry about balanced line connections. They will not help you. However, some amplifiers (like the latest ARC equipment) simply will not run properly with a single-ended source (our equipment does not care FWIW). So in such cases its a good idea to check with the manufacturer and make sure you don't have a compatibility problem.
OTOH, if you do decide to move to balanced operation (meaning you would change out the preamp), the use of balanced cables can have quite a lot of benefit if the preamp and amp support the balanced standard. The length of the cable does not matter; the reason for the benefit is that the balanced standard eliminates interconnect cable artifact. If you have ever heard a 1 meter RCA cable sound different from another one then you know what I am talking about. Its literally as if the cable does not exist in the system- its just pure signal, and the cost of the cable should be minimal.
While many offer both connectors, not all are optimized for balanced operation or as others have pointed out, compromise quality to accommodate them.
The SP20 I purchased in the summer is designed specifically to be run balanced (is quieter and generates lower distortion) and fortunately, the VTL power amp I've long used was too.
Other brands like Atma Sphere are likewise designed from the outset to run balanced.
We have fairly high CMRR numbers, so the gain and distortion from either the RCA or balanced input is the same.
I know you're very much an advocate of using balanced connections.
I very much appreciate your counsel on this matter about which I confess ignorance.
This has been a most helpful exchange. I have no noise or inference, at least any I can hear, with my present setup. I have used several moderately priced interconnects between my pre and power amps. A few of them sounded different but not better than my current set that are 12 foot RCAs.
George
One late comment. For 12 years I ran an RCA cable from my all-RCA pre to an RCA/XLR adapter into my Krell FPB 300cx, which accepts only XLR. I sued very high quality Cardas or BAT adapters. At one point I had an RCA/XLR Valhalla IC made. I detected no audible difference when the adapters were used, to be frank.
I now have a pre that has XLR outputs as well as RCA, and the mfr. recommends XLR, so I purchased high level XLR/XLR IC's. Again, no audible difference because of the terminations.
This was my experience, FWIW. Don't drive yourself crazy.
Neal
Not late and much appreciated. I am especially glad to hear from individuals such as yourself who provide several real-world examples from they own experience.
Thank you for writing!
George
I agree with the other postings on this (made by the time of my posting of course :-)).
I would just add that if you find yourself needing to feed RCA to XLR or vice versa due to a lack of alternatives then avoid the use of adaptors. You will better preserve your system's performance by having a custom set of RCA/XLR cables made.
> 1.) Do balanced connectors always sound better than unbalanced ones?No! Balanced components reject noise picked up by the interconnect but don't necessarily sound any better than unbalanced components. Very long connections tend to act like antennas and pick up noise. A differential balanced input sees only the audio signal and rejects any noise picked up on the interconnect. Usually, balanced interconnects provide no advantage in home stereos where the length of interconnects tend to be relatively short.
> 2.) Why is that the case?
I think some people want to believe that balanced components are better because professional components have balanced inputs and outputs. The reason, as stated above, is so that long cable runs can be used without collecting noise.
> 3.) For those in my situation, would I achieve better performance by using XLR-RCAs at one end and XLRs at the other or would this not yield any improvement?
No! If you require an XLR adapter on one end, it will make no difference in performance onto which end you install the adapter. You will save money by installing the adapter on the amplifier while using an ordinary RCA cable from preamp to amplifier. If you install the adapter on the preamp, you will then have to buy a balanced cable to go to the amplifier.
My advice would be to buy an amplifier with RCA inputs. Usually, amplifiers designed for home audio have RCA inputs even if they also have balanced inputs. It is possible that some amplifiers with balanced inputs only might be fully balanced internally and therefore suffer significantly when used with an RCA-to-XLR adapter. An amplifier of this kind would have a balanced signal at its speaker outputs and would provide only one-fourth its rated power when used with an RCA-to-XLR adapter.
Good luck,
John Elison
Edits: 01/18/15
I've played a lot with balanced and unbalanced ICs from my Oppo 105 (with tubed mods from ModWright) and have to say that balanced cables rule in this case. The balanced cables (running into balanced inputs on my Aesthetix Calypso linestage) increase the 105's output so that the volume level matches my other sources, and the connectors -- cheap Neutriks though they be -- lock into place and seem to me far more secure than even the best-sounding RCAs.Sonically, no difference that I can detect -- except, obviously, for the volume level.
BTW, I'm using only two of the three connections on the Neutriks, with nondescript wire soldered to the ground connector at one end but not connected on the other end, a trick I first read about here on AA (Jon Risch?). Needless to say, the ICs I'm using are DIY.
Edits: 01/19/15
Thanks for this - I was not previously aware that internally balanced amplifiers loose power if fed with an RCA-to-XLR adapter and I would be interested to know why this is.
I have (I think!) a fully balanced power amp (ARC VT130SE) fed by balanced XLR--> XLR inputs from a passive pre-amp. However, the CD player has only RCA outputs and these are connected to the pre-amp by a custom XLR connector on the interconnect. It sounds pretty good and powers the Martin Logan electrostatics well.
My question is: does the CD --> pre-amp RCA--> XLR connection have any adverse effect?
Many thanks,
garf
A fully balanced amplifier would be equivalent to a stereo amplifier that is bridged to mono. You connect a speaker to the two hot (red) output terminals so that each speaker wire contains an audio signal. An unbalanced amplifier has a signal on the hot (red) terminal only while the other is ground. Consequently, if you are providing a signal to only one speaker terminal of each channel on a fully balanced amplifier, the maximum power it can produce is only one-forth of its rated power.
If your ARC VT130SE is fully balanced, it will have an in-phase signal on the positive speaker terminal and a 180-degree out-of-phase signal on the negative speaker terminal. If it has only one audio signal on the positive speaker terminal with ground on the negative terminal, it is not what I consider to be fully balanced.
For example, I own a Parasound Halo A21 amplifier. It has both balanced and unbalanced inputs, but its speaker terminals have the audio signal on the positive (red) terminal only, so it's not what I consider to be fully balanced from input to output.
> My question is: does the CD --> pre-amp RCA--> XLR connection have any adverse effect?
That would depend on whether or not your preamp is fully balanced. A fully balanced preamp never combines the two signal legs of a balanced input. In other words, a fully balanced preamp has four discrete signal paths from input to output -- two for each audio channel. If your preamp is fully balanced and your amplifier is also fully balanced, then you will be able to extract only one-fourth of your amplifier's rated power when playing your CD player. If, on the other hand, your preamplifier combines its balanced input signals into a single path for each channel and then splits them into balanced signals again at its outputs, you are in good shape.
Best regards,
John Elison
Thanks John - and all the others below - for taking time to answer my questions.
garf
"I was not previously aware that internally balanced amplifiers loose power if fed with an RCA-to-XLR adapter and I would be interested to know why this is."
They don't necessarily lose power, they lose voltage gain. That's just due to seeing only half of the applied voltage. Probably the gain structure is such that that's still plenty to drive them to clipping so all you have to do to 'fix' it is to turn up the volume.
Rick
Thanks for this - I was not previously aware that internally balanced amplifiers loose power if fed with an RCA-to-XLR adapter and I would be interested to know why this is.
They don't necessarily lose power, they lose voltage gain. That's just due to seeing only half of the applied voltage.
Actually both statements are false unless the unit has poor Common Mode Rejection Ratio. If the ratio is high, the gain is the same using either input- RCA or balanced. Now if you apply half the input voltage, the amp will have 6 db less voltage output. That's not a gain issue- its simply not putting in the voltage in the first place.
My idea of a fully balanced stereo amplifier is one containing four discrete and separate amplifiers. In other words, each speaker would be powered by two separate amplifiers -- one being fed from Pin 2 of the XLR and the other from Pin 3. The output terminals to each speaker would both be hot with audio signals of opposite phase. In this configuration, if an RCA-to-XLR adapter is used, the amplifier being fed from Pin 3 will have no signal because Pin 3 is grounded in the RCA-to-XLR adapter. Consequently, each speaker can receive only one-fourth of the amplifier's rated power and voltage gain will be cut in half.
Best regards,
John Elison
Such an amplifier would have a terrible Common mode rejection ratio, which is actually pretty important if you want to run a balanced connection.
This is why transformers are often used as you can get really good CMRR numbers.
I'm not sure if I have ever seen such an amplifier or what it would be used for. I had a balanced Kepco lab amp years ago but even that employed a differential input.
But I see this idea a lot. It should be put to bed as such an amplifier is really just plain impractical.
Well, I didn't know that. I was basing this idea on several other posts I've read where people talked about a fully balanced power amplifier. So, you say it is very uncommon to have a fully balanced power amplifier? I do know that when stereo amplifiers are bridged to produce a mono amplifier of greater power, they basically operate like a fully balanced amplifier with a phase inverted signal on one speaker lead and the in-phase signal on the other. I just thought that perhaps there were fully balanced amplifiers designed that way, too.
I do know that some preamplifiers are fully balanced from input to output because I own one. My Pass Labs X1 preamp is fully balanced with four discrete signal paths from input to output -- two for each stereo channel. Most of my components are balanced but one of my two turntables uses an unbalanced phono stage, which is connected to one of my preamp's unbalanced inputs. The problem with the unbalanced inputs is that they send a signal only to Pin 2 on the output XLR. My X1 also has a balanced tape loop, which receives a signal only on Pin 2 from the unbalanced inputs. I have a TASCAM DA-3000 DSD recorder connected into the balanced tape loop and I recently discovered that when I make a recording from my unbalance phono stage, the loud passages are severely clipped yet the meters do not indicate a problem. In fact, I was unable to even get the meters to go into the red. Apparently, when I turned up the input level control on my TASCAM DA-3000, it actually clipped the input amplifier on Pin 2 because there was no signal on Pin 3 of the XLR. I now know that I can record LPs only from my other turntable with its balanced phono stage.
I suppose I could get around this problem by connecting my other phono stage directly to the TASCAM DA-3000's unbalanced inputs, but it is really not a concern since my other turntable sounds better for making recordings anyway.
Best regards,
John Elison
You may not know this but we made the first balanced line preamps offered to high end audio (1989- the MP-1; complete with balanced differential phono section). We also made some of the first balanced amps (1985).
However, they are also fully differential, which IMO is the way to do it- less parts and better performance (lower noise, less distortion). I'm not saying the balanced amps are uncommon, just that balanced amps that are also not differential (two discrete signal paths) are.
Bridged amps are an exception. I have dealt with a few of them that have a balanced input that only works if the amp is in bridged mode. Their performance is really not good!
Thanks, Ralph! I appreciate all the great information.
When you say there are plenty of fully balanced power amps, I interpret this to mean that the balanced input signal is converted to an unbalanced signal through a differential input stage before being sent to the power amplification stage. Am I correct? In other words, would you consider my Parasound Halo A21 to be a fully balanced power amplifier?
Thanks again,
John Elison
When you say there are plenty of fully balanced power amps, I interpret this to mean that the balanced input signal is converted to an unbalanced signal through a differential input stage before being sent to the power amplification stage. Am I correct? In other words, would you consider my Parasound Halo A21 to be a fully balanced power amplifier?
In our amps and preamps, the balanced signal never goes single-ended at any point in the circuit and everything is handled by differential circuits.
The Parasound I would expect has a differential input and then goes to push-pull in the driver and output section. So yes, its fully balanced even if not fully differential.
Usually a differential amplifier is used to convert from single-ended to balanced, but it can go the other way as well. In the case of the Parasound, I don't think so as it has a balanced input in which both phases are processed by the amp.
George-
if you are going to keep your ARC- stay w/ RCA.
1.) Do balanced connectors always sound better than unbalanced ones?
Absolutely not, and often enough it is the opposite.
2.) Why is that the case?
There may be extra circuitry or a transformer involved to allow for the balanced cabling interface to work properly. The unbalanced circuitry may not require any of this. (Note - this is component dependent)
3.) For those in my situation, would I achieve better performance by using XLR-RCAs at one end and XLRs at the other or would this not yield any improvement?
XLR's work well when long cable runs and noise are an issue. If you have neither, I wouldn't worry about using them. There's no specification for driving the cold leg of the XLR with signal, which is why you can get away with the adapter cable.
The idea of a 'cold leg' I have found frequently leads to confusion.
The idea with balanced line operation is to avoid putting signal current through the shield. The noise benefit is worthwhile even if the cable is only 6 inches. Length becomes irrelevant but the advantage is present in all lengths.
This is because the balanced line system is meant to get rid of interconnect cable artifacts in general. It is very effective at this if the standards are observed, which are often ignored in high end audio.
It is that latter point as to why there is still so much contention about this issue.
I think the real question you have to ask is whether these benefits are worthwhile if an input transformer is to be used to realize them.
I am actually an advocate for keeping things simple, as I suspect you are.
Where a transformer really works well is if you have a single-ended preamp, but have to run the cable a good long distance, something you can't do single-ended. Then a set of transformers at either end of the cable will be less colored than a single-ended cable of the same length with no transformers.
However, we don't use transformers in our gear and so can have a benefit even with very short runs. We've all heard differences between RCA-based cables and have often favored one over the other; often paid more for it. What if you could have the best cable made cost-no-object, but didn't have to pay the cost? That is what balanced line really offers.
DH Labs make shielded, directional, 'balanced' cables with RCA connectors, where (if I understand it right) the shielding is only attached to one end of the cable, and not the other, so that theoretically, you avoid ground loops because the shield is not in the circuit with the 'return' leg.
Is there a real benefit to this approach?
The advantage is that there is no signal current through the shield- the signal and ground get treated the same way, and the shield is merely shield.
Its not a perfect arrangement, but I would expect it to work a little better. We used to make interconnects in this manner many years ago back in the 1980s.
nt
To answer question 1) No.
With your preamp I would just forget about xlr altogether.
"We are all in God's hands... and God is a malign thug."
-Mark Twain
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