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question for CP33 owners


dazzjazz

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hi guys,

 

I have an issue with my CP33 and wonder if it's just my setup or a universal problem. First some background: I generally use mine on gigs, and use the mono piano sound.

 

The issue occurred when I connected my CP33 to my laptop via USB AND connect the stereo outs to my MOTU 896mkIII interface. With this setup I get a noise in the audio path that I found out is referred to as USB whine.

 

I called Yamaha service in Melbourne, and the very helpful guy suggested I get two audio cables made that were wired in an unusual way, to create some kind of earth loop, or perhaps to break an earth loop - I don't know.

 

So I've have these leads made and there is still a little bit of USB Whine, but the major issue is that I think my stereo outs are now out-of-phase.

 

I was trying to mix a track and the piano sound out of the CP33 just wouldn't be tamed. I flipped the phase on one channel and the mix improved when summed to mono, but still not great.

 

I realise this is a can of worms, but perhaps another owner out there can shed some light on this.

 

Why does this USB whine thing exist in the first place?

 

Darren

 

 

www.dazzjazz.com

PhD in Jazz Organ Improvisation.

BMus (Hons) Jazz Piano.

1961 A100.Leslie 45 & 122. MAG P-2 Organ. Kawai K300J. Yamaha CP4. Moog Matriarch. KIWI-8P.

 

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I just found the instructions for the wiring of the leads, not sure if today I had the stereo jack plugged into the interface or not - kinda forgot about that:

 

Works with interfaces that have a balanced jack input, such as MOTU 896 mkIII

 

1/4" mono jack on one end, 1/4" stereo jack on the other

tip connects to tip as per normal

sleeve of the mono jack connects to the ring of the stereo jack

the sleeve of the stereo jack is unconnected.

www.dazzjazz.com

PhD in Jazz Organ Improvisation.

BMus (Hons) Jazz Piano.

1961 A100.Leslie 45 & 122. MAG P-2 Organ. Kawai K300J. Yamaha CP4. Moog Matriarch. KIWI-8P.

 

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Technically, the cause of the noise is a ground loop issue. The types of power supply used on most notebook computers operates on a higher frequency than regular AC power lines (to reduce size needed of any transformer components).

 

The most effective cure would probably be to use a DI box that allows "ground-lift" between the CP33 and the notebook. In effect, a version of that is what is done using the tip and ring, but not the sleeve of the connector. However, phasing problems will definitely exist, since the signal is driving both sides of the notebook's audio with no ground reference. A proper passive DI provides an audio transformer that can not only change impedance of a signal, but also provide DC and power line isolation.

 

A properly designed DI will provide the needed isolation. I experience the same problem using one of my notebook computers, unless I am running the notebook in a powered docking station (which has a standard desktop type power supply).

 

Howard Grand|Hamm SK1-73|Kurz PC2|PC2X|PC3|PC3X|PC361; QSC K10's

HP DAW|Epi Les Paul & LP 5-str bass|iPad mini2

"Now faith is the substance of things hoped for, the evidence of things not seen."

Jim

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Diagnostically you can try plugging your compter in using one of these and see if the noise stops.

http://www.adorama.com/images/Product/ZZAC32.jpg

 

If it does you can then decide how you want to fix the condition. I don't now much about computers. So no way am I going to suggest you do this as a permanent solution because that may be a bad thing.

 

"It doesn't have to be difficult to be cool" - Mitch Towne

 

"A great musician can bring tears to your eyes!!!

So can a auto Mechanic." - Stokes Hunt

 

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Thanks everyone.

Can't check it out till Thursday.

Sven - I meant to say I only use the Mono sound on gigs, and haven't really used the stereo sounds much.

 

I think I'll be buying another DI...

www.dazzjazz.com

PhD in Jazz Organ Improvisation.

BMus (Hons) Jazz Piano.

1961 A100.Leslie 45 & 122. MAG P-2 Organ. Kawai K300J. Yamaha CP4. Moog Matriarch. KIWI-8P.

 

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There is USB whine and there is a buzz that comes from laptop power supplies. These are two different issues. If your noise goes away when you run on batteries, it's the power supply issue. If it goes away when you unplug the USB cable, then it's obviously USB. Regarding the power supply issue I have tried lifting the ground and using a DI. Neither solution worked for me. I can only tell you that some manufacturers' have this issue and others do not. I believe there are isolation devices specifically designed to reduce/eliminate the laptop power supply buzz, but I have not tried them.

 

Busch.

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I've got a cp-33 and just live with the whine.

 

But I've heard that if you use a STANDARD midi cable, the whine will be gone.

I just use the thing at home for practice and don't record much with it.

 

But you could try a midi<=>usb interface plus some midi cables.

 

Mahlzeit (I coulda spelled that wrong) on PianoWorld.com forums

told me about that.

 

Good luck to ya.

...Steve (writing my own midi sequencer - yeah, i'm crazy like that - http://pianocheetah.com)
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