Green Pres crosstalking?

Howdy all,

I've built a pair of the V14 greens, and have been using them exclusively for stereo recording using the ShinyBox ribbon mics (a nice combo). Given that the same program material was always going thru both channels, I never noticed anything wrong, until...

Last night, I was using them for separate tracks for the first time: one, a bass(D.I) and the other a vocal. Both channels were going directly to my recorder, and I noticed that some of the signal from channel 1 ends up going to the output of channel 2, and vice versa. When I say "some of the signal" I mean maybe 25% of the original volume. I have trouble-shot the whole system, and narrowed it down to the pres. Any ideas?

Could it be a grounding issue? I star grounded it as per Peter C's personal instructions. I have wired the outputs to TRS, so that I could interface with both balanced or unbalanced gear. In this case, the soundcard I was going to was unbalanced, and I was using a single conductor 1/4" to RCA cable. Would this have caused this? Does the output need to see a balanced input on my recorder?

I'm stumped...noob style!


Any help would be much appreciated,

Jacob

I had the same problem when connecting greenpres to unbalanced inputs.

I solved it by trying out a couple of different wirings for my cables...im sory but i cant remember which worked.

Its the cable anyway, and not the pres!

Good luck!

/Jonas

Jacob

Try this:

Plug a mic into Ch 1 & a set of cans into Ch 2's output & see if you can hear Ch1 in the cans. Try vice versa to see if there is a problem with the other channel. The 5532 on the output will drive a set of cans.

Peter

Hi

Just a guess but I wonder if some crosstalking could occur through the 6k8 resistors of the phantom power, mainly if an unbalanced input is used...

Regards

César

Likely you shorted one output to ground when inserting a TS (mono jack) which might cause crosstalk due to the large resulting ground currents (though this crosstalk should actually sound rather distorted).

Use a TRS (stereo jack) and do not connect anything to the ring.

Samuel

[quote author="cprieb"]Just a guess but I wonder if some crosstalking could occur through the 6k8 resistors of the phantom power, mainly if an unbalanced input is used...[/quote]
Nope.

The 6k8s are commoned at a 'kill' point, and the signal is cancelled. It's also usually shunted to ground, and should be a low-impedance source point anyway, so basically it's impossible.

Keith

Thanks guys, this gives me a few things to try.

Peter: I'll try the cans idea, as I guess that's the easiest way to rule out the pre as the problem. As per your email suggestion I made up a TRS to TS cable today like this, with no luck:

TRS side.....................Connect to................TS side:
Tip.............................................................Tip
Ring...........................................................Sleeve
Sleeve(shield connected).............................(unconnected)


Samuel wrote: "Use a TRS (stereo jack) and do not connect anything to the ring." So if I have this straight, this means I make a TRS to TS cable like this?

TRS side.....................Connect to................TS side:
Tip.............................................................Tip
Ring (unconnected)......................................(unconnected)
Sleeve........................................................Sleeve

If I am using regular mic cable, which connection gets the shield?

and BTW the crossed signal is not distorted, just quieter than the proper output signal.



Jonas: In this earlier thread that was posted, you mention what worked for you.

http://www.groupdiy.com/index.php?topic=14631&highlight=green+crosstalk

You wrote :

"green pre end xlr out: pin1=shield, pin2 pin3 connected as usual.

Soundcard end TRS jack: tip=hot, sleeve= ground and neutral connected. "

Are you referring to an XLR to TRS cable?


Jacob

yup!

Xlr to TRS, but if you use TRS outputs it should still be the same.

Try it!

I had hours of hairpulling before i got it right and without the crosstalk.

good luck!
/J

I'd think one of the points being common ways to unbalance a output
signal and often that is to ground the pin 3 , neg polarity , cold signal
the other version is to , as Samual said leave it unconnected

Sometimes depending on circuit the grounding pin 3 can cause distortion
but since you don't have this , hopefully the ungrounded version will help
simply leave the pin 3 unsoldered to anything .

let us know what fixed it for you , regards Greg

So if I have this straight, this means I make a TRS to TS cable like this?

Click to expand...

Yes, looks fine.

If I am using regular mic cable, which connection gets the shield?

Click to expand...

Sleeve.

Samuel

Thanks, gentlemen. This actually gives me quite a few things to try. The bummer is that since this came to light, I actually have gotten overwhelmed with work, so I haven't even really been able to do more than to make one cable, which made no difference.

I will do some poking around on Monday and post my results.

Cheers,

Jacob

I just had a moment of paranoia that I might also have the output jacks connected wrong

Since I am using TRS output jacks instead of XLR, what is the proper hookup, just to make sure my internal connections are correct?


Pin 1 = (I think gets star grounded to the power supply along with pin 1 of the inputs, right?)That's the way Peter C instructed me to do it.
Pin 2 = Tip Ring or Sleeve?
Pin 3 = Tip Ring or Sleeve?

( I just remembered that there are only 2 solder points off the output of the card, which are pin 2 & 3, if I can recall...)

I know, I'm a total noob, but grounding has never made sense to me.

( I just remembered that there are only 2 solder points off the output of the card, which are pin 2 & 3, if I can recall...)

Click to expand...

That is correct, the ground for the output would come from wherever the audio ground is for your project (most likely to be the sam as the input ground).

Peter

So, I know this is because I am a total newbie, but I still am not sure if I have these properly connected internally (as in from the cards output to my output TRS jack).

If I am using a TRS jack instead of an XLR, which do I tie to the input ground, Tip, Ring or Sleeve? By this I mean, which one acts as pin 1? Which one gets the pin 2 (hot) connection, and the pin 3 (cold) connection off of the PCB?

If I know that it is hooked up correctly internally, then I can focus on getting the cables right. I want it hooked up for interface with balanced gear (TRS on both ends) so I can connect it to my balanced computer soundcard. But I also want to be able to find the proper cable for hookup to my hard disc recorder, which has unbalanced RCA jack inputs. I need to be able to interface with both, but I am now doubting my internal wiring.

Any ideas? What would you all do if you were using a TRS output jack instead of an XLR?

Thanks for suffering my ignorance, I am trying really hard to grip this stuff.

Cheers,

Jacob

www.rane.com/note110.html

Samuel

Okaaaay,


I think I get it. I connect the sleeve to the audio ground, same as input pin 1, output pin 2 (from PCB) goes to tip, and 3 to ring?

Is that correct?

:thumb:

Samuel

Hi Jacob,

Typically a balanced = TRS is as follows:

T (Tip) = Pin 2 (Hot)
R (Ring) = Pin 3 (Cold)
S (Sleeve) = Pin 1

If you choose to go unbalanced into your sound card it is best to keep balanced on your preamp side, as above, and just change it on your TS soundcard side, which would be TS connector wired as.

T (Tip) = Pin2
S (Sleeve) = Pin1+Pin3

I hope that helps you.

Cheers

Matt

EDIT: You seem to have beaten me to it!

Sweet, thanks for the link, Samuel!

I can see this will come in handy to somebody green like me.

J.

Thanks for the reply Matt,


I think I just remembered something. I may have neglected to ground my outputs to the same ground as the inputs

so that may have been my problem all along. I was afraid I had something wrong inside, and it seems likely that I left the outputs ungrounded. It's been a while since I strung it all up, but if memory serves...

I get some time to tinker on Wednesday, so hopefully I can get this sorted out soon. Thanks again for all your patience!

Jacob