Question about Audio Interface Instrument Inputs and Active Pickups

[SgtHulka]

I am planning to purchase a PreSonus AudioBox 96 if this checks out. AudioBox USB 96 | PreSonus

I have seen several reviews for interfaces in general that you can damage the inputs by using active basses. One guy says, "Power User Tip: Active instruments are those that have an internal preamp or a line-level output. Active instruments should be plugged into a D.I. box, which should then be connected to the mic input rather than directly to an instrument input. Plugging a line-level source into the instrument inputs on the front of the AudioBox USB96 not only risks damage to these inputs but can also result in a very loud and often distorted audio signal."

What is his point? Is an active bass a "line level source"? Aren't line levels way above Low-Z or High-Z? Is the instrument input on this box capable of handling both active and passive basses?

The tech specs list the instrument impedance as "0.5 MΩ" which I understand as 500K Ohms. I know Ohms represent resistance, but not sure about how it is affected in this way. Although it doesn't say Hi-Z specifically, is 500Kohm considered Hi-Z? If what the guy is saying is right, is it because you essentially have your active bass onboard preamp, then going into another preamp the input is providing?

The main point is that I do not want to be forced to bring along a DI and connect to that first before going into the interface. I want to be able to take the interface mobile and be able to play through that alone to record without a DI, and without damaging anything.

 

[Tosh]

I have 3 basses with active systems. None of them are anywhere near a line level output. The oldest, a "passive/active" Peavey DynaBass, is actually a low-level HiZ output (somewhere around 1Mohm) and needs the most gain applied at the input (mine is a Focusrite Saffire Pro 40). My newest bass (Godin A4 Ultra SA) has a passive magnetic pickup (handy if your battery dies) and a set of active piezo saddle pickups, also HiZ, and needs less gain on the input, but still requires a HiZ (inst) setting.

If the bass output is HiZ ut on the hot side, then just turn down the gain, or engage a pad.

If the bass output is TRULY line-level, then it should connect to a line-in jack. I don't know of any guitars that are really line-level output.

Line level - Wikipedia

 

[SgtHulka]

I have 3 basses with active systems. None of them are anywhere near a line level output. The oldest, a "passive/active" Peavey DynaBass, is actually a low-level HiZ output (somewhere around 1Mohm) and needs the most gain applied at the input (mine is a Focusrite Saffire Pro 40). My newest bass (Godin A4 Ultra SA) has a passive magnetic pickup (handy if your battery dies) and a set of active piezo saddle pickups, also HiZ, and needs less gain on the input, but still requires a HiZ (inst) setting.

If the bass output is HiZ ut on the hot side, then just turn down the gain, or engage a pad.

If the bass output is TRULY line-level, then it should connect to a line-in jack. I don't know of any guitars that are really line-level output.

Line level - Wikipedia

Thanks for your reply. I have a feeling it's going to work, but I keep reading conflicting things about what a high z input really is.

Bottom line, will I have any problems at all plugging an active bass into an instrument input rated at 500 thousand ohms?

Any possible damage to the input?

Will the sound be weird in any way?

Sorry, I'm a recording noob.

 

[seamonkey]

Just watch the red light
It can flicker, that’s fine. It shouldn’t stay on.

 

[MonetBass]

I have an older model Presonus Audiobox USB interface and have recorded two different active basses (both 9 volt) without any issues.

 

[Wasnex]

"Power User Tip: Active instruments are those that have an internal preamp or a line-level output. Active instruments should be plugged into a D.I. box, which should then be connected to the mic input rather than directly to an instrument input. Plugging a line-level source into the instrument inputs on the front of the AudioBox USB96 not only risks damage to these inputs but can also result in a very loud and often distorted audio signal."

What is his point? Is an active bass a "line level source"? Aren't line levels way above Low-Z or High-Z? Is the instrument input on this box capable of handling both active and passive basses?

is 500Kohm considered Hi-Z?

That quote is actually directly from the user manual. IMHO it does not apply to basses in general, but it may apply to some keyboards. FYI, The signal of many keyboards actually does get up into the range that should be considered line level.

If you can plug your bass into the Instrument Input and set gain so that you can pluck hard without causing distortion you should be fine.

Many manufacturers would post a "Max Input Level" in their specs...can't find that info for the Instrument Input anywhere in the owner's manual. Perhaps you could ask Presonus?

Max Input for the Mic Input is listed as -3dBu. That's actually a pretty hot signal (>0.5V RMS). This is interesting because Mic Level is even lower than Instrument Level. It would be odd if the Instrument Input clips with a lower level signal than the Mic Input.

Here's an article you might find interesting: Line level, instrument level, mic level explained The article says instrument level is typically in the range of -20dBu, which is about 0.08V RMS. Mic level is down at -30dBu.

I would consider 500K Hi-Z, but of course it's not the highest. Modern instrument amps tend to use 1Meg. I have seen some with 10Meg, and 5Meg. Some older amps have 220K. All are High-Z

 

[SgtHulka]

Thanks guys.

 

[DirkP]

"The LA-610’s Hi-Z input is intended for electric guitar, electric bass, or any instrument with a magnetic or acoustic transducer pickup, and can be set to either 47K ohms or 2.2M (million) ohms. The 47K ohms setting is best suited for the -10 dBv level signals typically provided by active basses and guitars, while the 2.2M ohms setting is more suitable for instruments with passive pickup systems. Since a particular instrument’s output impedance may actually be somewhere between the active and passive levels, feel free to experiment to achieve the best sound at the desired level. Again, changing the input impedance will not harm your instrument or the LA-610."

The above is a quote from my LA 610 manual.
My Neve active DI has the same input impedance as my 610 for passive instruments: 2.2M.

500K on the Presonus seems to be inbetween or am I reading the numbers wrong?

 

[byacey]

500K is a reasonably high input impedance for passive pickups. Personally, I would rather see 1 to 10 meg ohm to reduce pickup loading, but 500K will work fine too.

 

[byacey]

Thanks for your reply. I have a feeling it's going to work, but I keep reading conflicting things about what a high z input really is.

Bottom line, will I have any problems at all plugging an active bass into an instrument input rated at 500 thousand ohms?

Any possible damage to the input?

Will the sound be weird in any way?

Sorry, I'm a recording noob.

High impedance is a relative term, but for line level sources, anything higher than 10K would be considered high impedance. For musical instrument sources with a high impedance source like piezo, magnetic guitar pickups, etc, I would consider anything over 250K high impedance.

Most active output circuits will drive anywhere from 600 ohm to infinity, but would be considered a relatively low impedance device with respect to instrument level.

 

[SgtHulka]

Another question...could I use the rear 1/4 TRS outs as additional headphone jacks instead of using them for mains? If so they would just be controlled with the master right?

 

[Wasnex]

Another question...could I use the rear 1/4 TRS outs as additional headphone jacks instead of using them for mains? If so they would just be controlled with the master right?

View attachment 4060815

Those outputs send Left on one jack and Right on the other jack. Each output sends a balanced line level signal that is not suitable for driving headphones (10dBu max). You could use them to drive a headphone distribution amp.

 

[SgtHulka]

Those output sends Left on one plug and Right on the other plug. Each output sends a balanced line level signal that is not suitable for driving headphones (10dBu max). You could use them to drive a headphone distribution amp.

Why is it then labeled 1/L and 2/R? I presume the 1 and 2 represent the 2 front inputs. What if I only use one input? It would output to the corresponding back input as a mono signal, yes?

It's also advertised as 2 in and 2 out...what is the 2 out part then?

Thx again dude.

 

[Wasnex]

Why is it then labeled 1/L and 2/R? I presume the 1 and 2 represent the 2 front inputs. What if I only use one input? It would output to the corresponding back input as a mono signal, yes?

It's also advertised as 2 in and 2 out...what is the 2 out part then?

Thx again dude.

Take a look at the manual, and see section 4.3.1 [Configuring Your I/O]. You can assign the inputs as mono or stereo. If you assign them as mono, I believe both Inputs will come out both Outputs. If you assign them as stereo you probably get 1L, 2R.

I could be wrong...the manual is not very clear or thorough .

To clarify, the image in your post was for the Studio 24C and that is the manual I used.

I have not looked at the manual for the USB96

 

[byacey]

Why is it then labeled 1/L and 2/R? I presume the 1 and 2 represent the 2 front inputs. What if I only use one input? It would output to the corresponding back input as a mono signal, yes?

It's also advertised as 2 in and 2 out...what is the 2 out part then?

Thx again dude.

Those outputs are meant to drive a 600 ohm load (if you're lucky) and higher. Dynamic headphones can be anywhere from 8 ohms to 300 ohms, which would overload a 600 ohm output. This is why Wasnex mentioned using them to drive the input of a headphone distribution amplifier.

 

[SgtHulka]

Take a look at the manual, and see section 4.3.1 [Configuring Your I/O]. You can assign the inputs as mono or stereo. If you assign them as mono, I believe both Inputs will come out both Outputs. If you assign them as stereo you probably get 1L, 2R.

I could be wrong...the manual is not very clear or thorough .

To clarify, the image in your post was for the Studio 24C and that is the manual I used.

I have not looked at the manual for the USB96

Yeah, I stepped up to the Studio 24C. I got a good deal on it and I realized it had thins I wanted, like the ability to record 192hz, better preamps, and a few other things. Appreciate the response.

 

[seamonkey]

ability to record 192hz

Just FYI - make sure you understand the repercussions of recording at 192khz
It good at some times, bad at others. It requires 4x the CPU power and 4x the storage of 48khz but may not always improve anything. Myself I've never seen any benefit over 48khz. And 48k mainly for mixing with video.

YMMV

Here's a great video on the subject

 

[SgtHulka]

Just FYI - make sure you understand the repercussions of recording at 192khz
It good at some times, bad at others. It requires 4x the CPU power and 4x the storage of 48khz but may not always improve anything. Myself I've never seen any benefit over 48khz. And 48k mainly for mixing with video.

YMMV

Here's a great video on the subject

Yeah thanks for that, I've actually done a bunch of research so far on it and it seems that 88.2 is The Sweet spot. I don't think I'll be recording much in 192 hertz but I did want to have the ability to do so if I wanted.