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ART Voice channel - gain control
Old 3 weeks ago
  #1
Here for the gear
 

ART Voice channel - gain control

Dear friends,

I have recently bought ART voice channel.

The manual clearly states that the GAIN knob should control both MIC and INST inputs.

Unfortunately, on my unit the GAIN knob controls only the MIC inputs (XLR) and rear LINE(balanced TRS jack), but not the front panel INST input (TS JACK).

Am I missing something here or my unit is defective?

Any help will be appreciated.

Best regards.
Old 3 weeks ago
  #2
Lives for gear
The manual text and the manual illustrations are unclear, but they dont seem to say what you think they say.
The manual states that the 1/4” front input is NOT part of the microphone preamp, and the pad has no effect on the instrument in. That would make you think that the preamp gain control has no effect on the front inst. input. That would seem to be describing what you have experienced.
BUT...the illustration has dashed lines from both the 1/4” and XLR inputs to the gain control, which would seem to indicate that the gain control is active on the 1/4” input as well.
Old 3 weeks ago
  #3
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MarkF48's Avatar
You are correct, the manual does state the GAIN control should affect the INST input. I tried to find a service manual or schematic and no luck.

- Are you using a 1/4" cable with TS plugs on the ends and not a TRS plug? The combo jack is supposed to 'automatically' switch from mic preamp to instrument when a 1/4" plug is inserted. The jack may rely on a TS plug to make a connection through the plugs sleeve ground to enable the switch (guessing on this).
- Is the INST input passing signal through the ART, even if you have no control?
- What is the instrument?
Old 3 weeks ago
  #4
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Quote:
Originally Posted by MarkF48 View Post
You are correct, the manual does state the GAIN control should affect the INST input. I tried to find a service manual or schematic and no luck.

- Are you using a 1/4" cable with TS plugs on the ends and not a TRS plug? The combo jack is supposed to 'automatically' switch from mic preamp to instrument when a 1/4" plug is inserted. The jack may rely on a TS plug to make a connection through the plugs sleeve ground to enable the switch (guessing on this).
- Is the INST input passing signal through the ART, even if you have no control?
- What is the instrument?
I tried using both bass and electric guitar.

Yes, I am using instrument cable with TS plugs.

The INST input is working, it has signal but it's fairly low level and I have to turn the OUTPUT LEVEL all the way up to reach about -3dB.

The unit is correctly switching the inputs. When I connect into the front INST input, it overrides the rear input - both XLR and JACK.

The REAR JACK is stated to be LINE level and part of the mic preamp. It is affected by the GAIN knob, but the manual states that it is balanced line level input, not intended for high impedance instruments.
Old 3 weeks ago
  #5
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MarkF48's Avatar
You've tried all the options to troubleshoot and it does sound like it has a problem. Not sure if it could be the problem with your Voice Channel, but I have a Pro MPA II that has had a problem with ribbon connectors not connecting well occasionally and losing signal. From an image of the Voice Channel I found there is a ribbon cable and connector going to a circuit board behind the gain control. You could try removing the the top cover and with the unit powered and an instrument plugged in with only one hand very carefully (do not touch anything else) jiggle that cable and see if anything changes with the gain. There is high voltage in that unit, so if you feel the least bit uncomfortable trying this I would recommend returning it to the seller.
Attached Thumbnails
ART Voice channel - gain control-art-voice-channel-1.jpg  
Old 3 weeks ago
  #6
Lives for gear
I disagree that you should think you and your individual unit have a problem. It is more likely that the manual is correct in parts but contradictory in others. Your explanation of your problem is in line with the parts of the manual indicating the front DI 1/4” input is NOT part of the mic preamp gain structure.
You should attempt to contact ART for an explanation or a more complete circuit diagram.
In saying that, I am aware from my own experiences that it is difficult to contact an actual human at ART for an answer to a technical question. But as of a few years ago it was possible, with persistence and patience.
Old 3 weeks ago
  #7
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Quote:
Originally Posted by MarkF48 View Post
the manual does state the GAIN control should affect the INST input.
To be precise, the manual does not STATE that, although one of the diagrams SUGGESTS that.
If I have missed something, please quote the text of the manual saying something like “the gain control should affect the INST input “.
Old 3 weeks ago
  #8
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MarkF48's Avatar
Quote:
Originally Posted by Bushman View Post
I disagree that you should think you and your individual unit have a problem. It is more likely that the manual is correct in parts but contradictory in others. Your explanation of your problem is in line with the parts of the manual indicating the front DI 1/4” input is NOT part of the mic preamp gain structure.
You should attempt to contact ART for an explanation or a more complete circuit diagram.
In saying that, I am aware from my own experiences that it is difficult to contact an actual human at ART for an answer to a technical question. But as of a few years ago it was possible, with persistence and patience.
Agree the manual and block diagram is a bit vague. what I get from the block diagram is there are two distinctly separate preamps, one for the mic and one for the instrument input. From the image I posted and it's not really clear unless one looks close, the gain pot is two ganged sections which I would surmise that one section is for the mic preamp and the second one for the instrument preamp. The dashed/dotted lines infer the linkage from the gain pot to the gain element. The instrument gain is variable +3dB to +40dB gain which the knob is not seeming to do. My guess is the ribbon cable interconnecting from the board the gain pots are located on back to the main board have lost connection and not able to vary the gain in circuit for the instrument preamp.

Finding and messaging a user of the Voice Channel on this board to have them try the instrument input gain control may be quicker than emailing ART
Old 3 weeks ago
  #9
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MarkF48's Avatar
Quote:
Originally Posted by Bushman View Post
To be precise, the manual does not STATE that, although one of the diagrams SUGGESTS that.
If I have missed something, please quote the text of the manual saying something like “the gain control should affect the INST input “.
You may have missed it ....
Attached Thumbnails
ART Voice channel - gain control-img_5111.jpg  
Old 3 weeks ago
  #10
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Quote:
Originally Posted by MarkF48 View Post
You may have missed it ....
Obviously I did. Thanks.
Old 3 weeks ago
  #11
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I already contacted ART, but not a word back from them.

I don't feel like buzzing people with personal messages about that.

I will be grateful if someone who owns an ART voice channel give his 2 cents on the topic.

I will check that ribbon cable, maybe it is an easy fix.
I just hope that there are no warranty stickers, because I don't want to mess up my warranty.

p.s. I don't mind getting electrocuted.. happens occasionally.
Old 3 weeks ago
  #12
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Quote:
Originally Posted by Poki View Post
I don't mind getting electrocuted.. happens occasionally.
It happens ONCE.
“Electrocuted” means dead by electric shock.
I suppose you wouldn’t care because you’d be dead.
I’m certain you wouldn’t be writing about it.
Old 3 weeks ago
  #13
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MarkF48's Avatar
Quote:
Originally Posted by Poki View Post
I already contacted ART, but not a word back from them.

I don't feel like buzzing people with personal messages about that.

I will be grateful if someone who owns an ART voice channel give his 2 cents on the topic.

I will check that ribbon cable, maybe it is an easy fix.
I just hope that there are no warranty stickers, because I don't want to mess up my warranty.

p.s. I don't mind getting electrocuted.. happens occasionally.
If this is a brand new piece of gear I would suggest exchanging it rather than opening it up. You shouldn't have to be fixing something brand new.
Old 5 days ago
  #14
Here for the gear
 

Just a little update.

I carefully checked the ribbon cable - it looked fine.
I tested the potentiometer with a multimeter and it seemed that the problem was not there.

Anyway I returned the unit and the replacement I got is working properly.

Best regards.
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