K+K Mini Pure Western Impedance Matching Question

[rockstar_not]

I want to build a small project enclosure box to aid my un-pre-amped Mini PW to the various input stages on my PreSonus Firebox.  I have the typical issue of too much low end and thump coming out of this thing.

Here are the details about the 3 different types of analog inputs available on this I/O device:

___________________________________

Microphone Preamp 1-2 (XLR Balanced)
   Type    Combo XLR Female Balanced / TRS 1/4"
   Frequency Response (±0.5 dB)    10 Hz to 50 kHz
   Input Impedance (Balanced)    1300 Ohm
   THD+N (unwtd, 1kHz @ +4 dBu Output, Unity Gain    < 0.005%
   EIN (unwtd, 55dB Gain, 150 Ω Input, 20Hz to 22kHz    -125 dBu
   S/N Ratio (Unity Gain, unwtd, Ref. = +4 dBu, 20Hz to 22 kHz   > 101dB
   Common Mode Rejection Ratio (1 kHz, 55 dB Gain)    >45dB (+12 dB digital boost switch)
   Phantom Power (±2 VDC)   +48 VDC
Instrument Input
   Type   1/4" TS
   Input Impedance   1 Mega Ohm
Line Inputs 3-4 (1/4" TRS)
   Frequency Response (+0,- 0.5dB)   20Hz to 50kHz
   Frequency Response (+0/-3.0 dB)   20Hz to 150kHz
   Input Impedance (Balanced)   10 KOhm
   THD+N (unwtd, 1KHz @ +4dBu Output, Unity Gain)    < 0.003%
   S/N Ratio (Unity Gain, unwtd, Ref. = +4dBu, 20Hz to 22KHz)   >101dB
   Maximum Input Level (Unity Gain, 1KHz @ 0.5% THD+N)   +20dBu
_____________________________________________________

Since I'm making the box myself, I can pretty much choose what to put into it.  My plan was originally about as simple as possible:

1/4" jacks on both ends of the box with a 1 MegaOhm resistor across the pins of one of the jacks and the signal pins on both jacks connected and ground pins connected.

+ ----------------+
    |
   1MOhm
    |
- ------------------ -

Simple, right?  but is that the right resistance value for the 1 MOhm instrument input on my PreSonus?

Then I thought, why not put in a 10MOhm potentiometer, and I can dial in the resistance depending on where I put the pot knob.

In this case my little circuit changes ever so slightly:

+-----------------+
      |
    Wiper of pot
      |
- ----------------- -

Then I saw that Rat Shack has 10M0hm pots with SPST switches built in.  I thought it might be cool to be able to silently switch off the axe with a switch, a mute button, if you will.  Question is, will a SPST switch be silent or at least better than the old 'yank the cord from the axe' pop?

-Scott

[ronmac]

The 1MOhm impedance of the Instrument Input on your Firebox should be appropriate for the K&K. Adding a resistor is not necessary.

Have you looked at other reasons that you are experiencing "low end thump"? Pickup placement, technique, etc.

[rockstar_not]

The 1MOhm impedance of the Instrument Input on your Firebox should be appropriate for the K&K. Adding a resistor is not necessary.

Have you looked at other reasons that you are experiencing "low end thump"? Pickup placement, technique, etc.

Pickup placement is the standard bridgeplate location for Mini PW pups.  The thump is unacceptable - happens on any palm muting action, hard stops, etc.  I did try this with a dedicated instrument cable with a 1MOhm resistor across the leads and it seemed to help significantly, but I lost the cable.

[ronmac]

Adding the resistor will change the frequency response, although you can achieve the same thing by using EQ, preferably parametric, and notch the offending frequency (likely 65~140Hz, the resonant frequency of the body) a few db.

[dberch]

Pickup placement is the standard bridgeplate location for Mini PW pups.  The thump is unacceptable - happens on any palm muting action, hard stops, etc.  I did try this with a dedicated instrument cable with a 1MOhm resistor across the leads and it seemed to help significantly, but I lost the cable.

Do yo have the ability to add a 80hz high pass filter?  that should take care of it. I had the same issue when I started playing my K&K equipped guitars through a bose L1 Model 1.  Never noticed this before, but it was pretty bad through the Bose.  the 80hz high pass on the guitar channel  ( cuts freq below 80 hz) did the job.  Lush fulll acoustic sound, but no more deep low thumping.

Hope this helps,
David