Distortion Using Hammond Xk-3 Organ

[iamspg]

I am setting up my new StageScape and have run into a problem with the fidelity of my digital organ (Hammond XK-3).

 

Problem:

The organ sound is distorted no matter what the trim or levels are set to, including using Auto-Trim and Trim Tracking.  Distortion sounds like digital distortion or clipping even though the input and output levels are around 0 dB or below.  (BTW - I am an electrical engineer with extensive analog/digital experience)

 

If I take the exact same signal chain and run into my Mackie 1604 analog mixer, the sound is clean.  Listening to the organ through headphones also sounds clean when the StageScape sound is distorted.

 

I've tried numerous signal path combinations and it makes no signficant difference. 

 

If I run my digital piano (Roland RD-700) or another line-level source (e.g. iPod) through the same input chain, everything sounds fine.

 

The Deep Tweak setting has EQ/compressor, etc. all disabled.

 

Setup:

All AC mains plugged into the same power conditioner.

Hammond stereo outputs into either balanced XLR inputs 11-12 or balanced TRS 13-14 (doesn't change the problem)

Alternate setup is to run Hammond through a passive stereo DI (with or without -20dB pad; with or without ground lift).  Doesn't change the problem.

 

Is anyone else using StageScape with a Hammond or other clonewheel organ? Has anyone else run into this?

 

Thanks for help/advice.

 

 

[iamspg]

Follow up to my own question:

 

After looking at the spectral analysis using using of the EQs, I see that the spectral peaks of the organ tones are much higher than the overall signal level shown on the input meter.  Whereas the input meter is reading -10 to -5dB, the spectrum is showing the indivdual organ tones (200-2500 Hz range depending on the drawbars and note played) as being +5dB (if I am reading the real-time spectral analysis scale correctly).  This is a huge difference.  Am I actually getting clipping distortion on those peaks?

 

Thinking that I might be saturating the input preamps, I've tried trimming the input gain much lower and then pushing up the output levels.  But this didn't really improve much and made it hard to get enough volume in the mix.

[iamspg]

One more follow up:

 

Contrary to what I said in my origial post, the Electric Piano (Rhodes, Wurly) from my RD-700 piano also exhibit similar distortion when I play with high dynamics.  Sounds with lower dynamics sound fine.

[dboomer]

The M20d is capable of better than +20 dB so it should not be a problem.

 

If you turn the trim all the way down do you still get distortion.

[jeanpicasso]

bump on this.

 

I use a XK3c with the M20D and havent noticed any distortion. so im very interested to find out what NOT to do.

 

if its any help, i have done just about nothing about the setup. i plugged it into one of the stereo groups, selected one of the preset (i believed it was "basic keys", autotrimmed, a litte tone adjustment in quick mode. nothing else.

[iamspg]

To answer dboomer:

 

I do get distortion with the trim all the way down.  When I originally plugged into line inputs and did an Auto Trim, the result said "inputs too hot".  Same thing when I plugged in my piano.  So I have tired running through DI boxes with -20db pads.  The Auto Trim no longer says too hot, but distortion still there.

 

Any chance I have a defective unit?

[dboomer]

There's always a chance that you have a hardware issue.  But it's not likely if other sources work satisfactorily on that channel.  Do you have the ability to try a different mixer at your dealer to rule out a mixer problem? 

 

btw ... when auto-trim says the signal is too hot that does not necessarily indicate a problem.  The auto-trim feature has a range that is can reduce and it will correct the signal to that amount.  But if you have a signal that is beyond it will still work but you will have lower headroom on that channel. You can simply turn dow the instrument if it has an output control or add a pad in line.

 

You also could try plugging into inputs 1-12 and get a different result.

 

But if you are still getting distortion no matter if you turn down the trim and your instrument and other sources do work on the channel I would be exploring the instrument itself or some kind of mismatch between your hammond and the mixer.  I can't find and tech specs on the Hammond wrt output level or impedance.  I assume you have tried using different cables?

[litesnsirens]

To this end, what is the overall range on the trim, it seems way beyond most mixers unless it's just the digital setup that makes is seem so.  Not to detract from the issues that iamspg is having, so far it seems I can plug anything into this mixer, passive, active and it can handle it all.  I'm really curious also to know what is going on with Iamspg's rig.  From the experience I've had with this mixer so far, I'm unable to imagine what's going on there.   It would be good to know if there is something to avoid.

[iamspg]

I found the problem.  It's the headphone amplifier that's distorting at levels above 12 o'clock.  When I run the main outputs to another mixer and listen with phones there everything is clean with plenty of dynamci range.

 

Is this normal (as in a known design flaw)  or a hardware problem?

[dboomer]

I found the problem.  It's the headphone amplifier that's distorting at levels above 12 o'clock.  When I run the main outputs to another mixer and listen with phones there everything is clean with plenty of dynamci range.

 

Is this normal (as in a known design flaw)  or a hardware problem?

 

What impedance are you driving from it?

[iamspg]

600 ohms.  AKG K 240 - an old model.