Much better VX2000 Sound - no hiss! at DVinfo.net

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Sony VX2100 / PD170 / PDX10 Companion
Topics also include Sony's TRV950, VX2000, PD150 & DSR250 family.


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Old January 24th, 2004, 10:32 PM   #1
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Much better VX2000 Sound - no hiss!

After owning a VX2000 for 3 years, I got tired of processing all my audio from the camera shots to get rid of the hiss in the background. I've read in the past that the BBC found a way to get rid of the hiss by an internal modification and using an outside portable mixer. You can read about this at:

http://www.bealecorner.com/vx2000/bbc-mod.txt

I've spent the past month studying the service manual schematics for the VX2000 and PD150 to figure out a way to duplicate what the BBC did. I work on electronics in my day job....

Well I finally got the guts to take my camera apart and do the modification. The built in mic still works when camera is set to AGC. When the camera is set to Manual Gain in the menu, the audio now comes from the RCA jacks on the camera sending high level 4 dBu into the AK4550 Analog-Digital converter... skipping the noisy and filtered mic amp chip in the handle, and on the main VC-242 board I bypass the Voltage Controlled Amp M5222FP that introduces even more noise. I have my mic going into a Sound Devices MixPre that feeds into my modified camera's RCA jacks that normally outputed sound during Camera operation. I can still monitor sound using the headphone jack (yes, it has noise but is not recorded on tape.)

I have some data to look at the results. I'm sure the numbers are not perfect as I don't have the equipment that Jay has But ran the RightMark test using a Audigy 2 soundcard producing analog test signal into my MixPre then into the camera. Before test was done going into 1/8" Line-In jack and After modification signal goes into RCA jacks on modified VX2000 in camera mode. Both tests were done using manual gain, levels at -6 dBfs (I had to use these hot levels to make RightMark program happy). Then I recorded the test signals and transfered them into my PC by firewire and saved them as wav files. Then I use RightMark to analyize the files to produce these reports:

http://www.gregjwinter.com/compare.htm

Like I say, since I not using a Terrasonde analyzer but you can get a general idea of the difference in sound quality the modification has made. I really like the fact that I do not have any more of that annoying hiss!

I may eventually post the changes I made to the internals of the camera. It is not an easy fix since you have to deal with surface-mount components. 6 tiny parts are removed and 2 small capacitors jumper the signal from tiny pads of the removed components. But if there is some interest I'll document it the best I can. I'm also considering doing it for other people, but I am not sure yet. -Greg.
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Old January 24th, 2004, 10:47 PM   #2
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The BBC fix is only for the VX2000, not the PD150.
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Old January 25th, 2004, 09:44 AM   #3
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P150

Yes, the bbc mod that they do is for the Vx2000, but the VC -242 is identical for the 150 and the VX2000 - they put some additional parts on the PD150 board... namely an extra voltage controlled amp M5222FP to control each L & R channel manual gain separately. You get better sound because they do not put the signal through that Mic Amp chip that is in the handle of the VX2000. However, if you still hear the hiss on the PD150, it's the darn M5222FP chip making all the noise. I'm sure Sony uses it since it's a cheap IC, but unfortunately has poor S/N figure.... that's why I bypassed it in my modification and use an external mixer.

So bottom line is that you can modify the PD150 if you want perfect sound out of the camera. -Greg
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Old January 25th, 2004, 10:29 AM   #4
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Thanks, Greg, for all that information.
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Old January 26th, 2004, 06:43 PM   #5
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A new part-time job for you? You could
probably get $100 a pop.
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Old January 27th, 2004, 02:40 PM   #6
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VX2000 Modification

Dave - well perhaps if I got really good at it.... it took me about 4 hours to do the modification, the first time I actually opened my camera. The next one I do will take me less time, and perhaps I could do it for $200. I have to take my time, especially if it's someone else's camera! :-)
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Old January 27th, 2004, 03:47 PM   #7
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Greg,
It's probably do-able.
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Old January 27th, 2004, 05:23 PM   #8
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Dave - when you are ready to do it, just contact me by email to make arrangements. -Greg.
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Old January 27th, 2004, 11:02 PM   #9
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Greg,

I'll be watching to see if you pick this up as a sideline and see how it goes.

I'd be curious to know if the mod could be made on a PD-170.

Of course, I'd probably wait till it's out of warranty, but I'm still quite curious about it.

Paul
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Old January 29th, 2004, 08:54 AM   #10
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PD-170

Paul - while I do not own a service manual for the PD-170, my guess is that it has a similar circuit topology. If it's anything like the PD-150 (I'm sure it is) then my modification should work fine. The sound from the PD-150 will get much improvement, but you will have to use an external mixer and not the built in XLR's in the handle assembly.

Yes, I too would wait until it's out of warranty :-)
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Old February 6th, 2004, 10:46 AM   #11
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Website Information

For more information about this modification and DIY info... please see this link: http://www.gregjwinter.com/modification.htm for more information.
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