[michaelv]

Hi,
  I have cdp which has true balance out XLR. However, my amp does not have it. So i was wondering if there is any real advantage of using XLR interconnect over RCA in short lenght, about 3 to 6 feet?  I don't have way to test it so I am asking your expertise for this.

thanks very much

[PaulHilgeman]

With that cable length it will probably not matter.

There are other factors at play though.  First, the DAC in your CD player is either natively balanced or single ended.  I would find out.  With my CD player, the balanced output is almost directly coupled to the DAC, the unbalanced output goes through another buffering stage.  This can make an audible difference.

The other thing is that balanced IC's can sound different than SE IC's to some extent, but the far greater difference will be how the equipment sounds out of either one of it's outputs or inputs (if your amplifier has both).  With amplifiers the grounding scheme and input stage of amps can chage pretty drasticaly depending on what type of input the amp uses, and similar things apply to the output of a source.

Maybe this helps, maybe not, but find out what DAC your CD player uses and report back, or just listen, thats the true test.

-Paul

[srlaudio]

Balanced connections ALWAYS are a better solution that unbalanced.  The common mode rejection is superior.  In your situation, however, there is not much to gain.  To truly gain all the benefits, the preamp should be designed as a balanced FROM INPUT TO OUTPUT.  Most equipment has a balanced input and output stage, but is unbalanced internally.  Transformers are always the best choice, only the highest quality should be used, and the electronics should be current type designs (discrete class A transistor or class A tube) .  Throwing a transformer on the output of an IC output stage is only good for ground isolation.  A true line driver would make the biggest difference.  The IC output sees a very high impedance input that doesn't load it in any way, then the aforementioned elecronics DESIGNED to drive a transformer complete the picture.  This scenario would improve any sound reinforcement system, but in your case I would just use High quality unbalanced RCA cords and leave the balanced bag of tricks for a whole system redesign.

[NewBuyer]

I recommend keeping the advantages of balanced connections in your situation, and using a Jensen PC-2XR to interface your CDP and amp.

[eico1]

... To truly gain all the benefits, the preamp should be designed as a balanced FROM INPUT TO OUTPUT....

What is the reason for that? The common mode rejection is attained at the point balanced is converted to single ended. The sooner the better I'd think. I agree about the ground isolation, that is probably the main reason one might perceive a difference between single ended and balanced.

steve

[Bob Reynolds]

To truly gain all the benefits, the preamp should be designed as a balanced FROM INPUT TO OUTPUT. 

I'm pretty sure that is not true. The common mode noise rejection occurs at the differential input. It is the difference "computation" that cancels the noise common to both the (+) signal and the (-) signal. In fact if the design stayed balanced from input to output there would never be any common mode noise rejection.

Transformers are always the best choice, only the highest quality should be used, and the electronics should be current type designs (discrete class A transistor or class A tube) .  Throwing a transformer on the output of an IC output stage is only good for ground isolation.

While I'm a big fan of transformers (Jensen in particular), I can't believe that they are always the best choice. Bill Whitlock has a patent on an IC balanced line driver that is supposed to be as good as a transformer. Also, many designers take advantage of the gain of an electronic differential input.

I don't see how the electronics has any bearing on the use of a transformer at all.

[Bob Reynolds]

Hi,
  I have cdp which has true balance out XLR. However, my amp does not have it. So i was wondering if there is any real advantage of using XLR interconnect over RCA in short lenght, about 3 to 6 feet?  I don't have way to test it so I am asking your expertise for this.

thanks very much

The advantage of balanced lines is their ability to cancel common mode noise at a differential input. Since your preamp does not have a differential input, you could use a transformer (the Jensen model already cited) at the preamp. If your ICs are well shielded, it's unlikely that any common mode noise would be picked up over the short distance you are talking about. Unless you know you have a common mode noise problem, I'd stick with the unbalanced ICs until you get a preamp with a differential input.

[Steve Eddy]

I recommend keeping the advantages of balanced connections in your situation, and using a Jensen PC-2XR to interface your CDP and amp.

I wouldn't recommend the PC-2XR. That uses their JT-10KB-DPC transformer which is a 4:1 stepdown transformer intended to convert pro audio reference levels to consumer audio reference levels which really doesn't have any relevance for most home audio situations. The PC-2XR will attenuate the signal by nearly 14dB.

I'm not sure if they make a CI-2 in an XR version, but even if they didn't, the cool thing about transformers is that they'll give you exceptional common mode rejection even when they're being fed from a wholly unbalanced source.

The CI-2RR gives 95dB of common mode rejection at 60Hz when driven from an unbalanced source.

se

[Steve Eddy]

While I'm a big fan of transformers (Jensen in particular), I can't believe that they are always the best choice. Bill Whitlock has a patent on an IC balanced line driver that is supposed to be as good as a transformer.

It's actually a line receiver, not a line driver. But as far as being as good as a transformer, ask Bill how much ground isolation it provides.

More info on it here: THAT 1200 Series - InGenius Balanced Line Receiver ICs

And as much as I like Jensen's products, I'd also like to make mention of another California-based company called CineMag. I've found their transformers to be every bit as good quality-wise as Jensen's, but at a price of about 20% less.

Also, many designers take advantage of the gain of an electronic differential input.

What, they've never heard of a step-up transformer? 

se

[warnerwh]

For anything under 6' I'd not worry about it one bit. If both pieces are truly balanced then I'd use the balanced connections because I have spare XLR cables laying around.

As far as sound quality goes it's not usually audible and if it is it's barely.  That's why alot of high end companies don't bother with XLR connections. I really see no need for them unless you have long interconnect runs. That's what they were designed for in the first place, runs of 100' are common in the pro audio world.

One place that using XLR's did help me was with a ground loop I had. The XLR connections eliminated it. If you have no problems though I'd not give it a second thought and just enjoy the system. Spend some money on room treatments or a Behringer DEQ 2496 and really make an improvement  in the sound quality.

[Bob Reynolds]

Steve Eddy, thanks for correcting my mistakes. I think Bill was saying that the IC balanced line receiver is comparable to a transformer at common noise rejection at a lower cost and would be superior to a conventional electronic balanced input.

Thanks for the link to CineMag.

You are right about the Jensen PC-2XR. Would the PI-2XR be the right choice?

Good point about a step up transformer.

+++++++

warnerwh, I agree with you 100% about the room and PEQ. I hope try a TacT in my system soon.

-- Bob

[Steve Eddy]

Steve Eddy, thanks for correcting my mistakes. I think Bill was saying that the IC balanced line receiver is comparable to a transformer at common noise rejection at a lower cost and would be superior to a conventional electronic balanced input.

Oh no, I know what the IC's about. Just couldn't resist a smartass comment.

Thanks for the link to CineMag.

Sure. They're good people. They don't mind working with DIYers and they're not terribly averse to doing custom jobs. With Jensen, if it's not something they already have in stock, they're not interested unless you'd be ordering 100 pieces.

You are right about the Jensen PC-2XR. Would the PI-2XR be the right choice?

Yes, that would be it. Thanks! I looked at the part numbering system and the CI units don't allow for any thing other than RR (i.e. RCA in and RCA out). I was thinking earlier that the PI-2 used an output transformer which I wouldn't have recommended in this case. But it does use the same input transformer as the CI-2RR.

Good point about a step up transformer.

Well that was partially a smartass comment too, but in all seriousness, I think a good step up transformer coupled to a good follower makes a very nice gain block.

se

[NewBuyer]

I recommend keeping the advantages of balanced connections in your situation, and using a Jensen PC-2XR to interface your CDP and amp.

I wouldn't recommend the PC-2XR. That uses their JT-10KB-DPC transformer which is a 4:1 stepdown transformer intended to convert pro audio reference levels to consumer audio reference levels which really doesn't have any relevance for most home audio situations. The PC-2XR will attenuate the signal by nearly 14dB.

I'm not sure if they make a CI-2 in an XR version, but even if they didn't, the cool thing about transformers is that they'll give you exceptional common mode rejection even when they're being fed from a wholly unbalanced source.

The CI-2RR gives 95dB of common mode rejection at 60Hz when driven from an unbalanced source.

se

Steve Eddy is more knowledgeable than I about these things - but that wonderful Ayre player michaelv owns is very well known for the quality of its balanced outputs, it would seem a shame not to use them! It will also produce full-output 4.5V on its balanced output, and his Plinius integrated amp shows an input overload spec of 5V rms. So if interfacing the Ayre's balanced outputs to the unbalanced inputs of the Plinius, wouldn't a 4:1 stepdown transformer be at least as appropriate for this application as a 1:1 transformer, while also providing better bandwidth and noise rejection specs? Perhaps the level drop is not necessarily a problem either, in fact companies like Rothwell make fixed in-line attenuators specifically to achieve a 10db level drop, for purposes of reaching a higher (and presumably better sounding) volume dial position.

Anyway, as I said above, I must defer to Steve on these things, he seems very knowledgeable (right Steve )and posts quite a bit around here, and helps lots of people in the process (me included).

[Steve Eddy]

Steve Eddy is more knowledgeable than I about these things - but that wonderful Ayre player michaelv owns is very well known for the quality of its balanced outputs, it would seem a shame not to use them!

Well, I wasn't suggesting that he not use them. Just that when I wasn't sure if the CI-2 was available with a balanced input, I thought I'd take the opportunity to point out a rather nice feature of input transformers.

That's all moot now that Bob finally made me realize that the PI-2 is essentially the CI-2 with options for RCAs or XLRs on both inputs and outputs.

It will also produce full-output 4.5V on its balanced output, and his Plinius integrated amp shows an input overload spec of 5V rms. So if interfacing the Ayre's balanced outputs to the unbalanced inputs of the Plinius, wouldn't a 4:1 stepdown transformer be at least as appropriate for this application as a 1:1 transformer, while also providing better bandwidth and noise rejection specs?

Certainly feeding it from a balanced source will give better noise rejection. But I've just got a "thing" about attenuating a signal only to amplify it once again. But that's just me and shouldn't be taken too seriously. 

Perhaps the level drop is not necessarily a problem either, in fact companies like Rothwell make fixed in-line attenuators specifically to achieve a 10db level drop, for purposes of reaching a higher (and presumably better sounding) volume dial position.

I dunno, things like that just seem like band-aids to me. It's basically saying that your system has a lot of excess gain. I just think the better way to deal with excess gain isn't to attenuate the signal, but to reduce the gain. Attenuating the signal doesn't do anything to improve signal to noise ratio or anything like that. Of course it's not often practical to reduce the gain so...

Anyway, as I said above, I must defer to Steve on these things, he seems very knowledgeable (right Steve )

Ohohohoho no no no no!

se

[twitch54]

For anything under 6' I'd not worry about it one bit. If both pieces are truly balanced then I'd use the balanced connections because I have spare XLR cables laying around.

As far as sound quality goes it's not usually audible and if it is it's barely.  That's why alot of high end companies don't bother with XLR connections. I really see no need for them unless you have long interconnect runs. That's what they were designed for in the first place, runs of 100' are common in the pro audio world.

One place that using XLR's did help me was with a ground loop I had. The XLR connections eliminated it. If you have no problems though I'd not give it a second thought and just enjoy the system. Spend some money on room treatments or a Behringer DEQ 2496 and really make an improvement  in the sound quality.

Excellent reply !! with all do respect to the more technical answers yours hits the mark, especially when mentioning "room treatments", arguably the least favorite yet most imortant "tweak money" to be spent !!

[michaelv]

Thanks.

I guess i would stick with rca ic right now. The reason i was asking because i have true balanced connection in my cdp, but my integrated amp does not. I just want to take advantage of XLR.

again,many thanks to all of you. Great info.

[rabpaul]

The manual on the Ayre C7e clearly states that a balanced connection will give you better sound quality than an unbalanced one.

The thing is XLR is not just about common mode noise rejection. In some CDPs e.g Classe the circuitry for balanced is not the same as for SE.

Can I suggest you at least try (even though your Plinus does not have true balanced) to see if you can hear a difference.