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balanced cables, inconsistencies w/ different speakers

post #1 of 11
Thread Starter 

Hello all

 

I am very sorry for this obviously beginner query, but there is one thing about the cables I am using that is puzzling me a little (ok, a quite a lot).

 

I am using two pairs of powered studio monitors; klein&hummels (neumann), and adam. I am feeding the K&H's with a pair of old XLR -> TS cable (I suppose it must be TS as I am only seeing one ring on the 'jack' end of it). This is working fine.

 

I then have a set of XLR -> TRS cables (I suppose that's what they are as they have two rings on the 'jack' ends) to feed the Adams.

 

Now however, when I tried to plug the XLR -> TRS cable into the K&H's, all I heard was HF, as if it was only the tweeter playing (or indeed, as if some signal was getting (phase?-)cancelled. I don't understand why this would be the case, and why would a technically 'better' cable (the TRS) perform incorrectly, while the TS cable is working fine.

 

BTW the Adams work fine with either set of cables.

 

Could anyone help me out as to what may be happening, and what I am doing wrong?

 

Thank you very much.

post #2 of 11

A good balanced output circuit with a 3 pin XLR connector has:

pin 1} Shield or chassis (this pin is not part of the audio circuit.

pin 2 } Signal [+]

pin 3 } Signal [-]

 

The 'TS' connector is expecting an audio signal between  one of the XLR signal pins (2 or 3) and the shield. Often balanced outputs have no signal output voltage between on of the signal pins and the shield.  When you hear only HF signal in this type of output it's due to leakage or high frequency in-balance.

 

****************************************************************

 

In this Doug Self paper, read the sections about "Impedance balanced output."

Balanced Line Technology.

http://douglas-self.com/ampins/balanced/balanced.htm

 

Note that this paper, pre-dates the emphases on separating the pin1 shield from the circuit ground.


Edited by Speedskater - 1/20/14 at 2:00pm
post #3 of 11
Thread Starter 

Thank you.

 

Would this explanation qualify given the fact that same cable only plays hi freq. content when plugged into one manufacturer's speaker, but plays fine when used with another speaker?

post #4 of 11

I don't know the powered speakers that you have. Please check your user manual and see if they are single ended input. My guess is both of them might support single ended only. The input jack is not universal. A single ended input is not compatible with differential input. The construction of the jack could explain the difference. The jack of the K&H might short the input of the cable and create a high impedance path that somehow interact with the input and form a HPF. This would be a guess since I have no knowledge of the K&H and I have trouble downloading a datasheet. Please check your user manual to confirm if the monitor takes differential signal. BTW, the single ended input and differential input are not interchangable unless they have some clever way to do auto switch.

post #5 of 11

Yes. That is a bit of a puzzle.

 

I'm afraid you will need to provide more information before anyone can do more than hazard a wild guess as to what is going on.

 

Such as. What are you using as the source? I'm assuming here that you are plugging the XLR ends of your cables into the speakers and the jack ends into an interface of some description? What is that interface and what is it being fed from? Which model ADAMs do you have? Are you using the same device and set of terminals to feed both speakers? What is the setting of the ground lift switch on the K&H?

 

Guessing is a good game so I'm going to have a go anyway while we wait for your reply.

 

The K&H are serious studio monitors. According to the block diagram they only accept input via balanced XLR. The ADAMs are more a hybrid monitor/listening speaker. They are designed to accept either balanced or unbalanced inputs (the RCA only stereolink feature is very handy and can save you a lot of money on a monitor controller).

 

So I suspect (remember I'm only guessing so don't get the hump if I'm wrong) the source you are using to feed the speakers is not a true balanced source. The ADAMs don't mind but the K&H do. It's still a bit odd though. So I await your reply with interest.

 

p.s. have you read page 11 of the 120 operating manual? Did that info help?


Edited by RonaldDumsfeld - 1/21/14 at 5:52am
post #6 of 11
Thread Starter 

Thank you all for the willingness to help.

 

Here's more info.

 

The signal is being fed (digitally) from a RME audio interface into a LAVRY DA10, which in turn feeds an input a passive monitor / volume controller NOS McONE (http://new-old-sound.com/products/20-mcone).

 

From this monitor/volume controller, I am running a par of XLR->TS cables to feed the K&H o300 with no obvious issues (K&H manual [please note it's not the D (igital) version, but the one w/ analog inputs : http://www.neumann-kh-line.com/klein-hummel/globals.nsf/resources/o300_o300d_manuel_e_520542_v02_20090529_1.pdf/$File/o300_o300d_manuel_e_520542_v02_20090529_1.pdf ).

 

Then another pair of outputs from the NOS McONE feeds the Adam S2X. I am using a pair of XLR -> TRS cables for that connection. Sounding fine.

 

Now if i were to use the XLR -> TRS cable (that currently feeds the S2X), and plug it into the K&H, all I hear is the tweeter playing very low.

 

If i feed the S2X with the XLR -> TS cables (that the K&H seem to be working with), the Adams play fine as well.

 

I can provide pictures if more clarification is needed.

 

Thank you.

post #7 of 11
Thread Starter 

Thank you all. I have since replied, but since my reply includes URLs to other sites, the post is pending moderator approval. Hopefully it appears here shortly.

post #8 of 11

Wow. That's close to $15k worth of gear just there. Nice work if you can get it.

 

Anyway given that info you posted above I'm totally stumped.  Hopefully someone else might chime in at this point.

 

You could try : -

 

Do all the McOne output pairs exhibit the same behavior? If so

 

Find an XLR > XLR cable you know works (or test it with the ADAMs first). Connect the K&H directly to the Lavry balanced out.

 

If the K&H work fine now then there's someone wrong with the monitor controller. If it still sounds **** it's the speakers.

 

Get in touch with either products tech support and tell them exactly what you told us.

 

Keep in touch. I'm intrigued and would like to know the answer.

post #9 of 11
Thread Starter 

Thank you. I am not at the studio right now, but I just got an idea that I feel silly hasn't occured before. I can use the audio interface's balanced TRS outs to try and use the cables [the ones that do not work correctly with the K&H via the monitor controller], and connect them directly from the RME to the K&H's, bypassing the monitor controller. Then buy another XLR-TRS cable and attempt the same. I am starting to have a feeling the store may have, after all, given me cables that aren't wired as expected-- do you reckon this could be a possibility? (Then again, why the heck would they work correctly with the Adams?)


Edited by aleksb - 1/21/14 at 8:44am
post #10 of 11

Yeah. That's a possibility. Most studios have a pair of balanced leads with the ground lifted at one end hanging around somewhere for when they get a ground loop. Maybe you picked them up without knowing.

 

It's all a process of elimination. Once you eliminate the impossible whatever remains must be true however improbable.

 

I reckon you are on the right track. Try another set of regular balanced  TRS > XLR and see if you get the same result.

 

http://www.rane.com/note110.html

 

Might prove too be useful info.


Edited by RonaldDumsfeld - 1/21/14 at 9:35am
post #11 of 11

The Mike Rivers paper on balanced to unbalanced interconnects.

 

"The Ins and Outs of Gozintas and Gozoutas"

– Mic, Line, XLR, TRS, levels, impedance, balanced, unbalanced – all about the inputs and outputs of audio equipment

 

http://mikeriversaudio.files.wordpress.com/2010/10/the_ins_and_outs_of_gozintas_and_gozoutas_revised.pdf

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