Detailed specs for inputs & avoid clipping with instrument (hi-z) signals

mendomusic
Posts: 9
Joined: Fri Jan 27, 2017 2:36 pm

Detailed specs for inputs & avoid clipping with instrument (hi-z) signals

Postby mendomusic » Sun Apr 01, 2018 3:08 pm

Hello,

I connected an e-bass guitar to the input 1 of KMI. For output, I used 2 quality nearfield active monitor speakers (7").

Then, I observed some clipping and distortion.

I checked with the Kmix specs.
The actual values for the inputs are not included in the K-Mix Technical Specifications
https://www.keithmcmillen.com/wp-conten ... pdf?x59479

Could you please provide more details on the characteristics of input 1 & input 2 which are Hi-Z Inst/Line 1/4” TRS Inputs (balanced)?

In this case when clipping & distortion occurs with instrument type of signals, do you recommend
  1. adjusting the Kmix on-board DSPs, e.g. compressor, gate & EQ?
  2. a dedicated (passive) DI box?
  3. an external effects processor with a limiter before routing into Kmix?

Thanks in advance!
TheOtherSupport@KMI
Posts: 721
Joined: Fri Jan 31, 2014 5:31 pm

Re: Detailed specs for inputs & avoid clipping with instrument (hi-z) signals

Postby TheOtherSupport@KMI » Mon Apr 02, 2018 4:13 am

We recommend using inputs 3 - 8 for signals that are too hot for preamps on inputs 1-2.
Inputs 1-2 will clip sooner as they apply more gain than inputs 3-8.
Was the trim at minimum?
Any reason you can't use the other inputs?
Can't you just turn the volume down at the source?
mendomusic
Posts: 9
Joined: Fri Jan 27, 2017 2:36 pm

Re: Detailed specs for inputs & avoid clipping with instrument (hi-z) signals

Postby mendomusic » Sun Apr 15, 2018 5:10 am

Thanks for the quick reply!

TheOtherSupport@KMI wrote:We recommend using inputs 3 - 8 for signals that are too hot for preamps on inputs 1-2.

The manual recommends the opposite for instrument signals....

TheOtherSupport@KMI wrote:Inputs 1-2 will clip sooner as they apply more gain than inputs 3-8.

This is logic if all is passed through a pre-amp to gain.

But why are they then called Hi-Z as well?

Do you refer them as Hi-Z as for mics (see further explanation here Impedance - When and when not to use HI-Z inputs? )

"A typical guitar, for example, generally needs to be connected to a Hi-Z input."
https://www.sweetwater.com/insync/hi-z/

So what's the definition used in the specs for hi-Z?

TheOtherSupport@KMI wrote:Was the trim at minimum?

==> This did the trick and solved it:

* I reduced the trims to 0 (Zero)
* I increased the channel faders to be up to the start of reddish part
* I increased the master faders to be up to the start of reddish part

TheOtherSupport@KMI wrote:Any reason you can't use the other inputs?

I just followed the manual:
2.3.4 – To Instrument Level Instruments & 3.4.3 – Instrument Level Input
I guess a bass guitar would still qualifies as "Hi-Z instrument level signals"

TheOtherSupport@KMI wrote:Can't you just turn the volume down at the source?

Sure. But the source has some limits.

As a more general feedback which explains the confusion with the trims & fader level:

1) I used to set channel faders on other mixers in such was that it never arrives at the red top part to avoid overload
With K-MIX, this seems to be different:
2a) the channel faders apparently do not indicate overload in the master or aux mode
2b) the channel faders apparently do indicate overload in the trip mode by a red light at very top of the fader
2c) for checking volume, obviously, the VU mode serves the purpose.

Concluding, what are your recommendations besides that for monitoring overload and avoiding it with K-Mix?
TheOtherSupport@KMI
Posts: 721
Joined: Fri Jan 31, 2014 5:31 pm

Re: Detailed specs for inputs & avoid clipping with instrument (hi-z) signals

Postby TheOtherSupport@KMI » Mon Apr 16, 2018 6:50 am

The manual recommends plugging instruments/hi-z inputs into 1 and 2, but if you're clipping those, then you either need to turn the trim down, or plug into 3-8. SO we're not really recommending the opposite.

There's way too much variance in the output levels of guitars and basses to give a one size fits all solution. I can plug my bass into 1-2, but it I turn up the low frequency on the EQ of the bass, I'll clip it.

Hi-Z has nothing to do with gain, headroom, or volume, it refers to Hi/Low impedance.

Your quote uses the word 'generally'. That's important to keep in mind, there are no hard and fast rules here. Do what works.

Use the trim mode to set input levels. All other modes are looking at output levels.

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