[sdiy] Source for TDA-470's / String Ensemble bleed

[Eric Frampton]

In this case it's not about specific notes, it’s about ranges, i.e. I hit any one note in (say) the top 8 notes of the keyboard, and all the notes within a roughly 8-note range of the note I struck, ghost. And if I hold down more than one note in that range, I hear the ghosting louder. It’s not like a single Ab ghosts up and down the keyboard.

> On Oct 15, 2017, at 3:51 PM, Mark G <mratx at aol.com> wrote:
> 
> If the notes that bleed are always the same (i.e., you always hear an A, F#, or whatever when you play other notes in the octaves) it sounds like the ghost notes are failures of capacitors in the envelope circuits for those specific notes. Happens all the time on Omnis, I would assume similar symptoms are from a similar cause in the String Ensemble.  I just repaired the same issue on my Omni, although it was just one note that went bad, I had the issue with multiple notes when I first got it.  
> 
> The chorus/level issues sound like something else, don't have a solution on those. 
> 
> 
> Mark 
> 
> 
> 
> -----Original Message-----
> From: Eric Frampton <eric at ericframpton.com>
> To: SDIY <synth-diy at synth-diy.org>
> Sent: Sun, Oct 15, 2017 1:22 pm
> Subject: [sdiy] Source for TDA-470's / String Ensemble bleed
> 
> Hi folks, I’m trying to suss out why the top two octaves of my String Ensemble are now bleeding across notes (i.e. play one note, slightly hear a handful of others). I noticed this got worse after I rebuilt the power supplies. I’m guessing it’s the TDA470’s in the gate section - seems to happen in both Violin and Viola (4’ and 8’), and only in the top 16 or 20 notes of the keyboard. Is there a reliable source for these? The seller of new ones on eBay right now looks kinda sketchy, and I don’t want to buy used ones. Are there other failure points I should check in the actual unit itself? Other symptoms are: the output is fairly low compared to a 100% working unit I have here, and the drop in level seems to happen before the chorus generators (i.e. the chorus generators are equally noisy in both units, but the uneffected signal level seems to be lower in my unit compared to the working one). And, the output is slightly scooped/hollow in the midrange, with or without the chorus switched in. This is a Rev 1, btw. e _______________________________________________ Synth-diy mailing list Synth-diy at synth-diy.org http://synth-diy.org/mailman/listinfo/synth-diy <>
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