Double Bass Ischell x48c(w/o battery pack) distortion help

Michael Drost

Michael Drost

Oct 16, 2009
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Grand Haven, MI
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#1
Hello,

I have been using the Ischell x48c without the phantom battery pack successfully for a year or so. I have an issue and wonder if anyone else has had the same problem.

I have the mic in position 1. This is best on my bass. Everything sounds great until I hit the open G string hard and I get a bit of distortion/clipping. My amp is an Acoustic Image. My slab and lifeline on the same bass sound fine through the cabinet. I have experimented with all of the compression settings. I sent Fischer an email, and haven't heard back so I figure I should check with my TB friends.

I have experimented with my back up Ischell mic and have the same results.

I love the Ischell, but this is driving me nuts. Any tips? Thanks!
 
#2
MDrost1 said:
Hello,

I have been using the Ischell x48c without the phantom battery pack successfully for a year or so. I have an issue and wonder if anyone else has had the same problem.

I have the mic in position 1. This is best on my bass. Everything sounds great until I hit the open G string hard and I get a bit of distortion/clipping. My amp is an Acoustic Image. My slab and lifeline on the same bass sound fine through the cabinet. I have experimented with all of the compression settings. I sent Fischer an email, and haven't heard back so I figure I should check with my TB friends.

I have experimented with my back up Ischell mic and have the same results.

I love the Ischell, but this is driving me nuts. Any tips? Thanks!
Click to expand...

No distortion until you hit the open G string hard? Does it happen at all gain settings on your amp? If so, I'm no expert but I'd hazard a guess that you're overwhelming the mic. If that's the issue, I think I'd try moving the mic to another position further away from the G bridge foot. If it doesn't happen at all gain settings, try a different amp/cab combo - maybe there's an issue with one of those pieces of eq
 
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#4
I would try reforming the putty doughnut with extra attention to making sure all areas are even and well seamless, then press it in just enough to get an excellent but not squashed seal. Lots of attention to detail. Then try it again. Can't hurt.
 
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#5
Sorry for the late answer Mike

You said you have a distorted sound with the open G but otherwise the sound is ok.
You have test it with your spare mic and it's the same, so I think it is not the mic.
If it is not a distortion created by the amp, so I think it is the bass.
Listen carefully it in acoustic to hear a possible vibration or something in the sound...
The mic can increase a small sound defect emitted by the bass.
 
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#6
So,

I did some trouble shooting.

I put it in other areas on my bass, and did not hear the distortion. I don't seem to notice and weird vibrations acoustically. I put it on my Golia carved bass. In the "1" position. Just fine. Cleaned all pots and switches on my amp. All good.

The drag is that the mic sounds best in position "1". It doesn't like that spot on my bass.

I believe Tom was correct. The mic was driven to hard in that area unfortunately.

I am going to noodle with placement, and the filter settings and see what I can come up with.

Thanks guys.
 
#7
MDrost1 said:
So,

I did some trouble shooting.

I put it in other areas on my bass, and did not hear the distortion. I don't seem to notice and weird vibrations acoustically. I put it on my Golia carved bass. In the "1" position. Just fine. Cleaned all pots and switches on my amp. All good.

The drag is that the mic sounds best in position "1". It doesn't like that spot on my bass.

I believe Tom was correct. The mic was driven to hard in that area unfortunately.

I am going to noodle with placement, and the filter settings and see what I can come up with.

Thanks guys.
Click to expand...

You might try changing the height of the mic above your bass, even a millimeter might make the difference - pull it out a bit in the putty, trying to keep it even above the surface.
 
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#8
I think of your problem, in my opinion,
> Tom is right in his post above, the pressure on the microphone is important. Less or more, it acts as a compressor and can therefore attenuate defects in dynamics or harmonics.
> But I do not think it's the mic that saturates because it receives too much sound
> If you do not find the solution, records a short sample, it may help to understand the problem with the type of saturation.
> Also pay attention to cables or things that can vibrate on the soundboard or the bridge at certain frequencies and produce sounds that may be similar to a distortion. For the ischell, use only a cable tie at 3cm from the microphone on the sounboard and the second on the tailpiece. If you have other microphones on the bass, remove them if possible or pay attention to these possible problems.
> Last thing, how was the high pass set ?
 
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#9
Folks,

Here is what I have done thus far.

1) Tried all HPF settings in 7 or 8 places.
2) Tried the mic on my Golia in position #1. Seems fine! Which is good.
3) Reinstalled on my hybrid. The distortion only happens in position 1.
4) Tuned my G to a G#. It went away. (Rick W would like this....: ))
5) I have tried every compression setting in every position. I am very familiar with the process, as I have moved/removed the mic many times.
6) Acoustically my bass isn't making any weird buzzing noises. Everything sounds fine acoustically.
7) Cleaned all pots and switched on AI head with Deoxit.

So, it has to be one of a few things:
1) My bass has an issue on the G bridge foot that I cannot hear acoustically.
2) The mic just doesn't like that spot on my bass.
3) Amp? Definitely not the cabinet, as I have tried it with multiple cabinets with no luck.

Onward and upward, my friends. Thanks for the help!
 
Last edited:
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#10
Do you have a bit of a wolf tone going on at G?

On my bass C is hotter than all the other notes, not so much that it jumps out acoustically, but some microphones really exaggerate the issue, presumably because a peak in their baked in frequency response coincides with the increased acoustic energy from the bass at that pitch.
 
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#11
Hey one other thing you might try: (being that the Ischell is worth the effort) is changing out the G string (go thru your collection of G strings) On my small bass the difference between one set of strings and another can make dramatic differences in the way the pickup responds. Might be worth it even if you dont want to change strings just to see if you can get the G string tamed.....
good luck
 
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#12
Well,

Had a gig this afternoon. I was hearing the distortion on many notes. Very weird, but good. I ran the Ischell through my portable Zoom multitrack recorder. I wasn't hearing the distortion. I am going to head to my local music store and buy a phantom power supply, and power the Ischell up. I plan on running it through my EA Micro and a MAS 26. Hopefully with positive results! Be back soon with results!
 
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