AudioBox USB, AudioBox Stereo and AudioBox Studio
Music Creation Suite (PS-49 Keyboard, Studio One, Notion, Nimbit, XLR cable, M7 Mic, Headphones and USB 2.0 Hub)
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I'm using a new Audiobox USB 96 and I'm working to get the cabling just right. I'd like to drive the Audiobox instrument inputs from my mixer line out jacks but the line levels cause distortion. I want to try to use some home-built attenuating cables, which very easy and inexpensive to build. The problem is I don't know the maximum instrument input signal (probably some dBu figure). When I know the max input level, I can formulate my attenuator resistor values.

Does anybody know the maximum instrument input level? It's not published in the product specs but, oddly enough, that figure is published for the mic input.

Has anybody successfully built and/or used attenuation cables with good results? If so, please tell us about them.

Thanks - John Speth
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by darrenporter1 on Sat Feb 15, 2020 10:45 am
What you need is a DI box. Line out to Inst-in/Mic-in is not just about level... it's also about impedance matching. I won't go into all the gory details, but you can look up why you need a DI box in this case and not just a fancy cable.

Radial is the brand of my choice.

Since it seems you have soldering skills you could consider one of these excellent DIY DI boxes too.... https://www.diyrecordingequipment.com/c ... ferrite-di


Studio One Professional 5.whatever, Harrison MixBus 32c v.6
i5-8400, 16GB RAM, 512 GB SSD, 2TB HD, Win10 Pro
UA Apollo QUAD, QUAD Satellite, PCIe DUO
FaderPort 8, Softube Console 1, JBL 306P Mk.II Monitors
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by darrenporter1 on Sat Feb 15, 2020 10:47 am
darrenporter1 wroteWhat you need is a DI box. Line out to Inst-in/Mic-in is not just about level... it's also about impedance matching. I won't go into all the gory details, but you can look up why you need a DI box in this case and not just a fancy cable.

Radial is the brand of my choice.

Since it seems you have soldering skills you could consider one of these excellent DIY DI boxes too.... https://www.diyrecordingequipment.com/c ... ferrite-di


Third option (and most expensive) is that maybe it's time to upgrade your interface to something better that has line-level inputs if this is something you will be doing regularly, but DI boxes are something you should always have around anyways.


Studio One Professional 5.whatever, Harrison MixBus 32c v.6
i5-8400, 16GB RAM, 512 GB SSD, 2TB HD, Win10 Pro
UA Apollo QUAD, QUAD Satellite, PCIe DUO
FaderPort 8, Softube Console 1, JBL 306P Mk.II Monitors
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by johnspeth on Sat Feb 15, 2020 12:46 pm
Thanks for the good responses. I've been warned by others that a simple resistive cable might not work. But I wonder: Shouldn't a non-inductive output (like a mixer) coupled to the instrument input by a simple resistive attenuator "just work", assuming the Audiobox USB 96 instrument input has no internal transformer (an inductive element)? Does anybody know if my assumption is correct?
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by SwitchBack on Sat Feb 15, 2020 1:47 pm
The goal is to get enough power from output to input with as little noise as possible. With ‘output-matching inputs’ these conditions are usually met because levels are correct, impedances are correct, and cables are used correctly. A (professional) line output expects a balanced cable to a balanced input with an input impedance of about 10 kOhms. Instrument inputs are not balanced and have an input impedance of about 1 MOhms. You may be able to reduce the line level to a level suitable for the instrument input and you may even be able to get the impedances right but it will never be a balanced connection. A long cable or noisy (EMI) conditions will cause problems.
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by darrenporter1 on Sat Feb 15, 2020 3:15 pm
Will it get signal into your Audiobox? Yes. But will it do it well?

johnspeth wrote I've been warned by others that a simple resistive cable might not work.


That should be the answer to your question right there.

IMO, the omission of line-level inputs on the Audiobox is the sole reason to not have one in the first place. It's such a basic feature that its omission is mind-boggling.


Studio One Professional 5.whatever, Harrison MixBus 32c v.6
i5-8400, 16GB RAM, 512 GB SSD, 2TB HD, Win10 Pro
UA Apollo QUAD, QUAD Satellite, PCIe DUO
FaderPort 8, Softube Console 1, JBL 306P Mk.II Monitors
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by johnspeth on Sat Feb 15, 2020 3:45 pm
darrenporter1 wroteWill it get signal into your Audiobox? Yes. But will it do it well?

I'm gonna try before spending another $100 for DI box and mic cables.

darrenporter1 wroteIMO, the omission of line-level inputs on the Audiobox is the sole reason to not have one in the first place. It's such a basic feature that its omission is mind-boggling.


That's my opinion too. Just about all interfaces in that price range have line level inputs.
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by johnspeth on Sat Feb 15, 2020 4:06 pm
I declare victory using my home-built attenuation cable. It's not an all purpose cable. It works for my setup (my -10 dBV unbalanced mixer output to a resistive divider built into a cable to the Audiobox USB 96 unbalanced instrument input).

The divider is a 15K series followed by a 1K shunt. There is a slight bit of noise at 20 dB gain and higher (digital bleed-through garbage and some barely identifiable AM radio). Recording levels are good at 0 dB gain. I'll see if I can live with it long term. I'll get the DI box if I can't.

Thanks everyone for the expert advice.
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by SwitchBack on Sat Feb 15, 2020 4:20 pm
Well done :)
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by johnspeth on Thu Feb 20, 2020 11:49 am
Well folks, I hereby withdraw my declaration of victory. I have found that digital noise from my PC is at an annoying but low level. I can't live with it. There is no hum, just digital noise. I can hear slight variations in the noise as my display changes so the noise source is unmistakable. My custom 23 dB attenuating cables do the attenuating correctly but won't slay the noise.

It's time to look at a DI box. Would this one solve my noise problem (ART DualZDirect passive DI box)?

The ART box has two channels with balanced outputs, a switchable 0/20/40 dB attenuator on the inputs, a 30 kHz filter on the outputs and a ground lift for full isolation.

Thanks - John Speth
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by darrenporter1 on Thu Feb 20, 2020 12:26 pm
Yeah, but honestly, as I said before, you are much better off getting an interface that has legit line inputs. You can still get the older "silverface" version of the Presonus 2|6 brand-new-in-box for only $118 at a couple Amazon retailers. The only difference between that and the 2|6c model is the USB-C connector. They both still use USB-2 and are identical except for the cable used to connect them and the color of the case, so there is some really outstanding value to be had there.

Something to consider, but yeah, that ART is a decent budget-level DI box.


Studio One Professional 5.whatever, Harrison MixBus 32c v.6
i5-8400, 16GB RAM, 512 GB SSD, 2TB HD, Win10 Pro
UA Apollo QUAD, QUAD Satellite, PCIe DUO
FaderPort 8, Softube Console 1, JBL 306P Mk.II Monitors
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by johnspeth on Thu Feb 20, 2020 1:32 pm
Thanks very much, Darren. Your advice has been very helpful. - JJS
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by colingaunt on Thu Jul 15, 2021 7:43 am
I read that you don't need to get the signal up to line level. That Audiobox does it onboard.

"The AudioBox USB and AudioBox 22VSL devices are designed to preamplify these weak signals"

https://support.presonus.com/hc/en-us/a ... -or-22VSL-

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