Art-Tube USB Dual Preamp Input Question

T

toneranger

New member
Hi Everyone,

Re the Art Pro-Audio "USB Dual Tube Pre" preamp: When I plug my shure 57 (micing my guitar amp) into the LEFT input of the unit I can get a decent signal from my DAW speakers. But when I plug it into the RIGHT input the signal is extremely weak, almost non detectable (the green signal light comes on when I play something however, so it seems like the signal is being picked up). Same cable is used in both input tests. I thought the SM 57 did not need phantom power, so I'm confused as to why I can't get a decent signal when I use the RIGHT input (which I'm thinking doesn't have phantom power, although I might be wrong on that, the phantom power might be for both left and right inputs, I'm not sure)

The unit's manual is here: http://artproaudio.com/downloads/owners_manuals/om_usbdualtubepre.pdf

Any ideas on what's going on? Thanks!
 
Hi there,
Welcome to HR!

The dual pre will have phantom power on both input channels but you were right; The sm57 doesn't need it and will 'ignore' it if it's turned on.

If you plug headphones directly into the Art unit and set the mix knob all the way to the left (computer) then test your mic in each channel. Can you hear it?

That takes your computer and software completely out of the loop, just to prove the hardware.

It looks like the unit has some basic compression and a 20db pad so make sure that all of the switches are set up identically for left and for right.
Try that and let us know. :)
 
Thank you Steenamaroo,

So I did what you suggested, disconnected the USB cord from my computer and the signal comes through on the headphones whether I use the left input or right input. But I have to select the 20db gain for each input when it's being tested (whether it's left or right) and crank it almost all the way up to hear the signal. Without the gain selected and cranked, can't hear much.
 
Take a look at the position of these two switches and try changing the position of each in different combinations. These could possibly do what you describe, particularly the STEREO/DUAL switch (I think). I'm guessing the STEREO/DUAL switch should be out for DUAL and the MONITOR switch set to IN for MONO for what you're trying to do.

STEREO/DUAL switch
This switch controls the preamp LEFT/RIGHT LEVEL controls. Stereo mode changes the two knobs from independent control over the two outputs to a Master volume (left knob) and Balance (right knob). This is useful when you have a stereo input signal and need to control the level of both inputs at the same time.

MONITOR switch
Depressing this switch will sum both input channels together for the Preamp source of the MIX control. This is useful when recording a single input and listening to it through both left and right headphone or Monitor outputs while listening to a stereo return from the computer (via USB). This switch does NOT affect the signal presented to the A/D converter or the INSERT jacks.
 
arcaxis said:
Take a look at the position of these two switches and try changing the position of each in different combinations. These could possibly do what you describe, particularly the STEREO/DUAL switch (I think). I'm guessing the STEREO/DUAL switch should be out for DUAL and the MONITOR switch set to IN for MONO for what you're trying to do.

STEREO/DUAL switch
This switch controls the preamp LEFT/RIGHT LEVEL controls. Stereo mode changes the two knobs from independent control over the two outputs to a Master volume (left knob) and Balance (right knob). This is useful when you have a stereo input signal and need to control the level of both inputs at the same time.

MONITOR switch
Depressing this switch will sum both input channels together for the Preamp source of the MIX control. This is useful when recording a single input and listening to it through both left and right headphone or Monitor outputs while listening to a stereo return from the computer (via USB). This switch does NOT affect the signal presented to the A/D converter or the INSERT jacks.
Click to expand...

Thanks Arcaxis,

Tried that with all the combinations of Stereo/Dual and Monitor switches engaged/disengaged: end result is the same, get a clear signal when I plug in my cable to the LEFT input and no signal at all when I plug into the RIGHT input.
 
mjbphotos said:
Are you selecting the right input (probably listed as channel 2) in your DAW?
Click to expand...

Thanks Mike for your thoughts.

I'm using Ableton Live 8. Selecting channel 1, 2, or 1/2 (under "Audio From Ext In") seemed to make no difference for the LEFT input (where I get a nice signal output) and also for the RIGHT input, where I'm not getting a signal.
 
toneranger said:
Thank you Steenamaroo,

So I did what you suggested, disconnected the USB cord from my computer and the signal comes through on the headphones whether I use the left input or right input. But I have to select the 20db gain for each input when it's being tested (whether it's left or right) and crank it almost all the way up to hear the signal. Without the gain selected and cranked, can't hear much.
Click to expand...

Ok great. That proves your headphones and physical hardware work.
You should set the monitor mix knob back to 'computer' for now.


toneranger said:
Thanks Mike for your thoughts.

I'm using Ableton Live 8. Selecting channel 1, 2, or 1/2 (under "Audio From Ext In") seemed to make no difference for the LEFT input (where I get a nice signal output) and also for the RIGHT input, where I'm not getting a signal.
Click to expand...

If you hear input from hardware input 1 whether 1 or 2 is selected in software, that suggests a routing issue within Ableton or any other software that might take control.
I don't know Ableton I'm afraid, but you're in good hands. ;)
 
Are you pretty sure each of the DAW speakers are working properly? Bad cable to a speaker or a plug that's not all the way in? Swap cables and speakers around(?)
From the block diagram for the interface the headphones and monitor outs look to be sort of the same connection-wise internally.
 
arcaxis said:
Are you pretty sure each of the DAW speakers are working properly? Bad cable to a speaker or a plug that's not all the way in? Swap cables and speakers around(?)
From the block diagram for the interface the headphones and monitor outs look to be sort of the same connection-wise internally.
Click to expand...

I'm using the same cable to test the right and left inputs on the preamp.

One thing I noticed is that when I plug the cable xlr into the left input (the one that gives me the signal), I hear a loud pop, but when I plug it into the right input I hear a very low volume pop. Does that mean anything? Could it be that the right input is just damaged?
 
Troubleshooting is about proving things in order to inform the next stage of troubleshooting.
The results of what I asked you to do prove that both physical inputs/preamps work, as you were able to hear input whether connected to preamp 1, or 2.

Arcaxis is asking about your output path.
If you have speakers then that would include those and whatever cables you have feeding them.
If you're using headphones-only then don't worry about it, as long as you can confirm that the left+right ears definitely work.

You're not using any adapters or anything that could be causing issues there?
If you play a source of commercial music, are you getting both ears OK?
 
This..
"Unlike previous versions of Windows, Windows 7 defaults to a single channel and adds too much gain to the signal coming though USB audio devices. There are some things you will want to change in "Control Panel > Sound Settings" to get Windows 7 to work with 2-channel USB audio products. a) The default setting for the input is 1-channel / 16bit/44.1K. In "Properties", change this to: 2-channel/16bit/44.1K. b) Windows sets the Mic input gain very high by default, so this needs to be reset. c) Use the "Configure" button in the Sound window to access the Speech Recognition section and select "Set up Microphone" and select "Other" under the input type. d) Run a signal into the USB device and run the Windows 7 Speech Level Program, following the prompts. After this, the gain levels will be appropriate, and both channels of the unit will be recognized."

Could be moot? From the Art ^ manual. I am very surprised to find that device is 16 bits only and is a 'Generic USB CODEC' this means it cannot used ASIO drivers and thus is prey to the untender mercies of Msoft. Yes, try Audacity since that won't handle ASIO either, it can be a bit 'counterintuitive' to get setup but there are plenty of bods here that know enough to help.

Dave.
 
I have since looked up that Art pre amp and it has been discontinued in a lot of places and discounted to under $100 in others. Makes you think they were a bit of a problem?

Dave.
 
ecc83 said:
This..
"Unlike previous versions of Windows, Windows 7 defaults to a single channel and adds too much gain to the signal coming though USB audio devices.
Click to expand...

Good lord. Next time someone has the audacity to suggest that MacOS and windows are 'the same', remind me of this. ^^
 
Steenamaroo said:
Good lord. Next time someone has the audacity to suggest that MacOS and windows are 'the same', remind me of this. ^^
Click to expand...

Well, yes but. I do know that W7 defaults to 100% for gain but I did not know of the 'single channel' mode. I have had several 'USB CODEC audio devices but never had that problem.

I have only ever SEEN a mac, never so much as touched one but they must HAVE a default audio condition?

But all this really goes to show that advice on HR should always be to shunt peeps away from the very cheapest whale ***t solutions and as bottom line go for an AI with TWO mic pres, 24 bit coding and ASIO drivers. As someone who started with PCI cards (Terratec, anyone remember them? ***t people) I would like to also add that an AI is not really worthy of the name unless it has MIDI ports. I will unbend to accept 3.5mm TRS for the really dinky stuff.

Dave.
 
ecc83 said:
Well, yes but. I do know that W7 defaults to 100% for gain but I did not know of the 'single channel' mode. I have had several 'USB CODEC audio devices but never had that problem.

I have only ever SEEN a mac, never so much as touched one but they must HAVE a default audio condition?
Click to expand...

The default condition is stay out of the way, it's got nothing to do with you. :p
Seriously though, input levels and any other controls are greyed out for any interface I've ever used, because they are, and should be, hardware controlled.
Sample rate/bitdepth/clock etc are selectable, of course.

I do have OS input control for audio from webcam/headsets, so it seems safe to assume that control comes from the manufacturer, not the OS.

Some interfaces will allow Mac OS to control the master output level - Some wont.
Again, presumably down to the manufacturers rather than the OS.

ecc83 said:
As someone who started with PCI cards (Terratec, anyone remember them? ***t people)
Click to expand...

EWS88MT, latterly the phase88? I started with one of those. :)
 
ecc83,

That was it! Thank you SO much. And thanks to the others here for their troubleshooting too.

Changed the setting to 2 channel/16 bit and now both the left and right inputs are being recognized by Ableton and I can finally get to experiment with my 2 mic setup (SM 57 and condenser mic). Just did a test and I got some decent balanced signals from both mics and the wave on the recording comes in nice and fat.

Re this: "Could be moot? From the Art ^ manual. I am very surprised to find that device is 16 bits only and is a 'Generic USB CODEC' this means it cannot used ASIO drivers and thus is prey to the untender mercies of Msoft."

What is the significance of this. What are ASIO drivers used for generally?

And what's the most affordable good/reliable dual channel mic preamp you all would recommend?
 
Great news! ECC to the rescue, again. :)

The main benefit of asio drivers is lower latency operation where a good driver from the manufacturer is not available.
Any interface from Motu, Presonus, Tascam etc is likely to have its own driver with that sort of thing in mind, and/or direct monitoring, often with built in digital effects.

Latency becomes a problem when we want to record and hear ourselves back in 'real' time and don't have these options.
You have a direct monitoring knob which means you will be able to hear yourself in REAL real time, but the audio you hear is tapped directly from the hardware and doesn't go through your daw,
which means you won't be previewing or availing of any software effects or processes. (sometimes it's nice for the singer to hear a reverb, for example).

If this stuff doesn't matter to you, then it doesn't matter. :)
 
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