Turtlerock Forum

Hi all,

Wonder if anyone has seen this sort of noise before - any tips appreciated.

I'm getting some noise when recording my MalletKat (electronic MIDI marimba with Kurzweil sound engine) - the Kat guys suggested that it was mains hum... but I have since done a spectrum analysis and there's nothing prominent at 50/60 Hz - it's noise across the range at about -40 when peaks are at -4.

I recorded 1 min of noise with a 15 second lead in - you can see the shelf in the pic links below:
http://dl.dropbox.com/u/9910326/Mallet% ... 7%20PM.jpg
http://dl.dropbox.com/u/9910326/Mallet%20noise%202.png

and the mp3:
http://dl.dropbox.com/u/9910326/Mallet%20noise.mp3


many thanks

Sounds like the same sort of noise I get if I run my ART preamp with too much gain. My guess, crappy amp noise.

Thanks Kurt - that was what I thought too but was hoping I was wrong.

I sent the pics and soundfile across the the manufacturer - their tech is reviewing it, but they already offered me a replacement amp board......

A good update and kudos for Alternate Mode (manufacturers of the MalletKat). Their techs checked out my analysis pics and soundfile.

They offered me the option of a replacement amp/sound board OR a refund for the faulty board OR a full refund on the unit - excellent service from a U.S. based company. I went with the replacement board - probably a few weeks before I receive and install it. More to come.....

Nice result. Hope it fixes it!

Well, the replacement sound board arrived and I gently pulled the back off the MalletKat to replace it... very tentative as I didn't feel like breaking such an expensive item.... replaced the boards which was fairly straightforward (8 screws and about 6 pin-cables) making sure I grounded myself each time I touched anything.

Powered it up and tested .. hmmm - there's an earth hum .... checked the instructions and cable locations - all ok - retested... hmmmm - there's still an earth hum. Checked the cables and found that the volume (up/down buttons) weren't working. Moved the pin-cables for these to the only other pins (1 step sideways). Retested - no hum and the volume buttons were working. Cursed the dodgy instructions and patted myself on the back for analysis.

With the new sound board there is audibly less noise when the level is cranked up to full. I still have to do another spectrum analysis to verify but it's looking good so far. Sent the faulty boards back to Alternate Mode who said they would refund the freight cost when they receive them. Looking good

Talk about a circular journey....!!!!.....

About a week after replacing the soundboards I turned on the mallet for a morning practice session and it was going HUMMMMMMMMM - when I touched a metal part the hum stopped - earth loop?

Either way, I decided that this was not good in a new and expensive piece of equipment, so I contacted Alternate Mode asking if I could return the item.

Now here's some praise for an overseas company - they agreed with no argument - they even let me use their account with Fedex to return the item. I had to pay the return freight, but that was deducted from my refund.

They were extremely helpful and polite in our email correspondence and I can recommend their service highly.

At the end of the day I'm $340 out of pocket for a 1-way freight charge, which is unfortunate but not complaint worthy.

Sticking to drumming now