High Hz "roll off" on Juno 106 voice - bad chip?

Hi folks, I have a Juno 106 that’s had the voice chip job done a few years ago. I was playing around in test mode and noticed that voice 6 has what sounds like a high frequency “roll off”. You can’t hear any difference when you’re playing the keyboard but when you cycle through the voice chips in test mode you hear a difference on voice 6. Does this sound like a bad voice chip? It’s not the typical voice chip failure issue. Here’s a YouTube video that describes the issue. https://youtu.be/d62NdigrfQk



The calibration procedure should take care of that, and cause all voices to sound identical when you cycle through them. Do you know if a calibration was done when the voice chips were replaced? (It should have been done, and the procedure is in the service manual.)

Hi Sam,
I calibrated the whole unit and it still does it. I followed the procedure in the service manual and the videos online. Used a scope and waveform generator in the procedure.


I just watched and listened to the video, and it’s pretty subtle (at least on my computer speakers). Seems like it’s more a change in timbre rather than just filter. Since those are original Roland voice chips, there could be differences between them, but I’m not sure what specifically would cause this. I’d bet that replacing them (or just the voice 6 chip) with Analogue Renaissance chips would give you consistent voices - but that’s a bit of expense and work that would probably be hard to justify, after the work you’ve already done.

If it were me, I’d call it the beauty of analog - not every voice is identical, which adds interest to the overall sound.

Or if you wanted to dig further, you could program a simple square wave program, and then look at each voice using the O-scope to see if it is really square. It sounds like voice 6 has some extra overtones.

Thanks Sam, Funny you mention that because I was thinking the same thing – do I want to fix this just because I can hear it during the test and see it on the scope and therefore it “must be fixed” or “I can’t hear this when I’m playing - maybe it adds character?” :slight_smile:

While I have you, is it typical practice to leave the “plastic” on the 3 DCO chips when removing it from the 6 voice chips?


I haven’t personally ever removed it from the DCO chips. We did it out of necessity on the voice chips, and never needed to save a DCO chip that way. Then we started slangin’ the Analogue Renaissance products, and never even think about removing that epoxy now - and since AR also makes the DCO chip clone, when we’ve needed to, we just replace the original Roland DCO with a new AR one. It saves a tremendous amount of time, we don’t have to breathe and mess with acetone, and the end result is bulletproof. (Even a ‘cleaned’ Roland voice chip still has a chance of failing.)