Dodgy 3340s

Fraser, Colin J Colin.Fraser at scottishpower.plc.uk
Thu Jan 7 11:57:12 CET 1999


> -----Original Message-----
> From: Tony Allgood [mailto:oakley at techrepairs.freeserve.co.uk]
> Sent: 07 January 1999 21:17
> To: synth diy
> Subject: Re: AW: VCO-1C #2
> 
> 
> Ingo wrote:
> I'm asking because in my selfmade poly synth (without 
> autotune) nine of
> the ten 3340s are pretty stable, after a warm up time of 20 minutes or
> so. But one is drifting very much. I thought that one had 
> gone bad, but
> maybe I just had luck with the other nine?
> 
> Tony writes:
> Me too. I have two bad ones out of 16 VCOs. I replaced the really bad
> one with another and I think its liveable with. I have just 
> been mailed
> by someone, Colin F I think, who said that Roland selected their CEMs
> for the Jp8. I don't know whether thats true, but some 3340s 
> are better
> than others. They will always be fine for a mono, it is as you say, a
> real bummer in a poly. 

Kevin L has a copy of the Roland service bulletin about this at
http://www.synthfool.com/cem3340.gif 
Roland selected the 3340s for the JP6, MKS80 and SH101.

Seems like that later production runs weren't so good...
Someone recently said somewhere that Roland may still have stock of spare
3340s, which would already be selected, so that may be a good source.
Personally, I'm not planning on using 3340s again (except for replacement if
a Pro-One vco dies). It's cheaper and not much more difficult to build a
stable discrete oscillator.

Colin f






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