Main analog audio output to an amp

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Main analog audio output to an amp

Postby corvax » 13:12, 15 May 2017

Hi everyone.
When I just bought my FA I have used a cheap audio cable to connect it to my mixer. I had some hum from the speakers and was sure that this is due to the cable. Then I bough a pair of good (short - 1m) mono jack cables for each channel separately. but the hum didn't go.
When I put the master volume knob in the FA on more than half way up, the hum gets pretty noticeable from the monitors. There seems to be nothing wrong with the mixer and downstream as I have other sources connected to it no problem even with cheaper cables.

Did somebody have a similar problem?
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Re: Main analog audio output to an amp

Postby Skijumptoes » 13:25, 15 May 2017

There should be no more noticeable hum when you turn the volume up on the FA itself, that would suggest that you may have a mic or external input going in to your FA that is creating the noise?
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Re: Main analog audio output to an amp

Postby corvax » 15:06, 15 May 2017

Skijumptoes wrote:There should be no more noticeable hum when you turn the volume up on the FA itself, that would suggest that you may have a mic or external input going in to your FA that is creating the noise?


No, there is nothing plugged into the FA
corvax
 
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Re: Main analog audio output to an amp

Postby PugFace » 12:49, 16 May 2017

you must use balanced TRS cables as the FA requires this. I use van damme cables as they are great quality and the heads are not too heavy to put pressure on the output connects of the FA.

sounds like you have a ground loop within your mixer. Which you need a ground lifter. I use the behringer one. Also if you have the USB connected you definitely need a ground lifter.

https://www.amazon.co.uk/d/pud/Designac ... +van+damme

https://www.amazon.co.uk/Behringer-MICR ... +destroyer
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Re: Main analog audio output to an amp

Postby Skijumptoes » 13:16, 16 May 2017

Interesting, i didn't even know they were balanced TRS outputs, i'm so used to having xlr's on other equipment. I may have to try a pair on mine as i do sometimes get the odd interference if my mixer/monitors are set high.

However, just thinking in the OP's case, if there was cable interference, surely that wouldn't worsen with the volume knob on the FA being increased, would it? If the unwanted noise is before the volume pot then it would be going out on both Tip and Ring (Via TRS) and therefore wouldn't/couldn't be removed via inverting phase which is what a balanced connection does.

Corvax - you need to perform a true test of whether the noise worsens when moving the FA's volume knob, if it doesn't then 2x TRS/Balanced cables to your mixer (If it supports balanced inputs) would definitely be a great move.
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Re: Main analog audio output to an amp

Postby corvax » 14:09, 16 May 2017

PugFace wrote:you must use balanced TRS cables as the FA requires this. I use van damme cables as they are great quality and the heads are not too heavy to put pressure on the output connects of the FA.

sounds like you have a ground loop within your mixer. Which you need a ground lifter. I use the behringer one. Also if you have the USB connected you definitely need a ground lifter.

https://www.amazon.co.uk/d/pud/Designac ... +van+damme

https://www.amazon.co.uk/Behringer-MICR ... +destroyer


PugFace
Thanks a lot. I thought that I was using the incorrect cables but wasn't sure that these do affect the sound so much. I have just ordered a pair of TRS ones. Will try this first and then if this didn't help will try the ground lifter.
corvax
 
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Re: Main analog audio output to an amp

Postby corvax » 14:13, 16 May 2017

Skijumptoes wrote:... if there was cable interference, surely that wouldn't worsen with the volume knob on the FA being increased, would it?

You are right. I tested this again carefully and found that the FA's volume knob has no effect the hum at all. The hum increases when I increase the monitors volume. So this must be the cables issue definitely (or the ground loop as PugFace has suggested. Have just ordered a pair of TRS will see how they behave.
corvax
 
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Re: Main analog audio output to an amp

Postby Skijumptoes » 14:18, 16 May 2017

Yeah hope it fixes it for you, great shout by PugFace, as i wasn't even aware that the FA had balanced outputs so i'll be getting myself some of them too, i used balanced where possible, and it can make a massive difference.

Ground loops tend to have a bit of a static tuneful/whistle hum to them, whereas the type of interference that a balanced cable would remove has more motion to it. Both are a pain in the ass, and depending on how you're gear is connected you can experience both quite easily! :-)

If the hum doesn't go, also try and ensure that all your audio equipment is on the same mains extension/splitter cable, as this helps reduce ground loops. It's when a second ground exists (i.e. using multiple mains power sockets) that loops become a problem.
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Re: Main analog audio output to an amp

Postby PugFace » 12:34, 18 May 2017

Its easily un-noticed as most synths are TS. My virus TI has TRS which alerted me to this new trend as i checked out the manual before i bought my FA. I think most of the poly-synths nowadays being released are TRS. ie. I think the Deepmind12 is TRS. not sure. Its better in any case as on stage as it saves using a DI box. I feel it also allows the output to breath better in the cable but thats just my gut feeling.

In my time the number of hums i have had in my set up have driven me to dispair. It seems if i add another synth i get a hum from somewhere.

If you ever want a very compressed loud, full of detail, sound out of the Fa invoke the limiter effect and play around with the EQ settings in a studio set to get best out of the bass end if you need it. The Fa, particularly with the Synth sounds, can roar like a Moog. Its sound engine is far more in your face than a Virus which now sounds polite. The virus does not have a limiter unfortunately. But be careful the Fa is a speaker wrecker.
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Re: Main analog audio output to an amp

Postby corvax » 19:53, 26 May 2017

Now using the TRS cables, clear sound, noise's gone! Great! Thanks guys!!
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Re: Main analog audio output to an amp

Postby PugFace » 21:25, 29 May 2017

That's great. I have found this forum very useful myself. The fa still surprises me with its sound. I keep going through the presets and many are a bit boring but then one will stand out. I always wanted a d50 years ago but could not afford it so I bought the d20. Now I have d50 aplenty and more in the fa. I Av managed to get a great thunderous moog Taurus pedal programmed and its the one sound that everybody thinks is impressive. Very Rush sounding. My virus ti can't do it but the fa can. If you want moog sounding progs you have to go away from the standard waves and move to the pcm waves in an sns. There's some fat pcms that are very analog.
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