A16 (Vers 1) Cabling Enquiry

nitty gritty · Post by **nitty gritty** » Thu Oct 28, 2004 5:38 pm

How do I connect my outbaord gear e.g.
Access Virus to my A16 (vers 1). The A16 takes 1 stereo balanced/unbalanced 1/4" jack per channel as stated in the manual.

So what will my outboard gear outputs take??

Should I use unbalanced stereo 1/4" jacks in mono output channels (of my synths)??

Ive tried balanced mono jacks at both outputs and inputs(Virus output L + R to a16 input 1 + 2)but I get no sound through the adat inputs.

Any help appreciated.

Regards, Andy.

wayne · Post by **wayne** » Thu Oct 28, 2004 6:39 pm

don't push the jacks all the way in to the a16 - they should be sticking out about 7-8 mm. Only a balanced cable should go all the way in (recommended in the manual)

nprime · Post by **nprime** » Thu Oct 28, 2004 7:55 pm

Really?

I've got all my unbalanced gear hooked up with regular 1/4" cables.

Never got a manual with my A16.

R

wayne · Post by **wayne** » Thu Oct 28, 2004 8:05 pm

AFAIR it is to avoid overloading the inputs

astroman · Post by **astroman** » Thu Oct 28, 2004 8:58 pm

at the A16's input side it's not supposed to be dangerous, but the outs aren't decoupled from the circuit, so they can in fact be damaged - as has been reported here.

cheers, Tom

nitty gritty · Post by **nitty gritty** » Fri Oct 29, 2004 2:52 am

In that case should I be using stereo balanced jacks for best results - even from my synths mono outs?

wayne · Post by **wayne** » Fri Oct 29, 2004 3:30 am

thanks, Tom

astroman · Post by **astroman** » Fri Oct 29, 2004 6:25 am

in fact a balanced mono plug looks exactly like a stereo unbalanced one, but as said you can safely use a regular mono input cable.
The signal will just be lower in level, it's quality isn't affected at all.
What will be affected is the driving of the conversion stage. For obvious reasons you'll loose some signal-to-noise ratio, but ONLY the part that is directly introduced by the converter itself. Not the general SNR (!)

Since output stages of synths (and fx gear)vary a lot in analog quality, it's there where you want to put the focus.
Is that output stage as noisefree as intended on it's own - otherwise it wouldn't make sense to make the signal balanced (this will cost at least something).

But since it would be just too simple this way

, there are also expensive DI stages with sophisticated transformers that are said to HAVE an influence on the sound themselves - in other words: they alter the input signal.

It's exactly that question I'm asking myself. Will there be a true gain in quality by one of those units - or will I spoil the input signal with a cheapo one ?

On the other hand it has to be noticed that the decoupling of the input stages eliminates most of the possibilities for ground loop problems.
And under such conditions even a cheapo box can improve the sound by removing some of the omnipresent background noise.

So how would you decide then

anyone knows THE unit applicable which does this job best ?

cheers, Tom

Counterparts · Post by **Counterparts** » Fri Oct 29, 2004 6:49 am

astroman wrote:

But since it would be just too simple this way , there are also expensive DI stages with sophisticated transformers that are said to HAVE an influence on the sound themselves - in other words: they alter the input signal.

I think that impedance mis-matching does effect the sound of the signal though; a guitar needs to plug into something with quite a high impedance to match its own circuitry.

Also, the reactance part of an input's impedance does vary with frequency (so a given impedance is really only true for a particular frequency!)

Hign impedance outputs (e.g. guitar) connected to a cable effectively increase the impedance of the whole transmission line. A high impedance cable run such as this is more adversely affected by the cable's capacitance than a low-impedance cable run. The cable's capacitance and the impedances of each end all set-up a filter effect on the sound. Mis-matching the impedances changes the nature of this filter quite dramatically. A good reason to use balanced impedances and low impedances for longer cable runs!

edit:
What I've said isn't quite the whole truth, which is in order to preserve signal level and frequency response, it's important to drive equipment with a source signal that is lower in impedance than the equipment's input impedance. Otherwise both SNR and frequency response suffer.

Royston

[ This Message was edited by: Counterparts on 2004-10-29 07:53 ]

ThomasT · Post by **ThomasT** » Fri Oct 29, 2004 7:39 am

>don't push the jacks all the way in to the a16 - they should be sticking out about 7-8 mm. Only a balanced cable should go all the way in (recommended in the manual)

Does this mean they are "phase inversed" (polarity switched).

Normal balanced jack:
tip = (+) positiv signal = XLR 2
ring = (-) inverted signal = XLR 3
shaft = (GND) ground = XLR 1

Either the unbalanced signal "first click" variant or the balanced signal will be inverted!

Strange...

nitty gritty · Post by **nitty gritty** » Fri Oct 29, 2004 1:49 pm

Thanks Tom and all for your help, but I'm still unsure what to do.

I was of the opinion that a stereo plug wouldn't work in a mono output (i.e. square peg in a round hole scenario) but perhaps I should just go buy a pair of balanced stereo cables and try them out.

If that worked then buying an expensive loom/s wouldn't be such a hard decision to make.

Post by **garyb** » Fri Oct 29, 2004 2:25 pm

you need to cut the ground on the instrument end when using stereo balanced cables with an unbalanced device. the problem is not the inputs of the a16 but the outputs(according to the post above), so you only need to be concerned with signal coming FROM the a16 TO an external nonbalanced device(sampler, recorder, effect, mixer).

trouble is seen when cold and ground are connected together in a ic balanced device that is not protected against this. that shorts out the ic and then nothing works anymore. pushing the cable part way in connects only hot and cold, but it also inverts phase. using a tip/ring/sleeve balanced(stereo) cable and connector is a better idea, lifting the sleeve on the device end.

nprime · Post by **nprime** » Fri Oct 29, 2004 2:56 pm

Hmmmm...so basically it's a miracle that I haven't ruined anything!

Amazing!

Is it because I only used unbalanced cables? Everything sounds great and I have no unusual noise floor problems...wierd...what you don't know can't hurt you? That's not my normal experience.

R

[ This Message was edited by: nprime on 2004-10-29 15:56 ]

[ This Message was edited by: nprime on 2004-10-29 16:03 ]

nprime · Post by **nprime** » Fri Oct 29, 2004 3:02 pm

Just a little terminology note, re: the original post question.

The A16 accepts TRS 1/4" plugs. TRS meaning tip ring sleeve, this is for a balanced mono audio signal. It is not a stereo input, although such a cable can be used for that purpose. The A16 inputs are mono balanced, not stereo.

R

[ This Message was edited by: nprime on 2004-10-29 16:02 ]

Post by **garyb** » Fri Oct 29, 2004 3:07 pm

nprime, i believe this only applies to the original a16.

good job clearing up the terminology too...

nprime · Post by **nprime** » Fri Oct 29, 2004 3:09 pm

That's what I am using, the original A16...go figure!

R

Post by **garyb** » Fri Oct 29, 2004 3:10 pm

there you go!

nitty gritty · Post by **nitty gritty** » Fri Oct 29, 2004 4:49 pm

Nice one Gary, that makes things easier
to comprehend.

blazesboylan · Post by **blazesboylan** » Fri Oct 29, 2004 5:08 pm

Rod's comments go for the Ultra too. Including the fact that unbalanced cables work fine with it on inputs and outputs. (Though at -6db.)

Most audio gear doesn't let you short the ICs these days. It didn't even occur to me it would be a problem until deejaysly pointed it out to me a few months ago! But as long as an IC-based unit has proper balancing (either via transformer or via "electronically balanced" magic), you can't short the output balancing ICs.

Incidentally here's a great site on balancing:

Balancing info

Here's the diagram depicting a quasi-floating or "electronically balanced" output: