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Awake77

Listen to your JD-800 for me...

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play a patch, generally one with higher pitches as its easier to hear...as the sound fades to silence, do you hear a subtle 'break up' right before it gets to zero? Or is it just me?

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Thanks guys, much appreciated. With the RF issues Im having with my JD's output, Ive just been really keen on anything that doesnt seem right...

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just raced back from work on my bike to test my JD, phew!! :D

 

Its way hot over here at the moment!

 

Tried a number of presets, high notes then low notes, volume 65% - 70%. Cant hear any break-up on the tales of notes. Tried basses, strings, pads and brass sounds, but no obvious distortion.

 

What are you listening through? also, does it do the same break-up through phones and outputs???

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Thanks for checking into it flat earth!

 

I can hear the breakup through headphones when I have the output volume cranked to 100%. The problem arises when I have patch cords plugged into the main outs and into my interface...RF interference (a low volume, high pitched whine), and that break up noise becomes more apparent.

 

Im worred that my JD-800 may have some impending issues here...

 

Any idea what this could be?

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didnt you post a thread not that long ago about another problem you were having with your JD at high volumes ? Maybe thats connected in some way.

 

It could be anything, a dry joint, failing component etc. Might be worth taking to a local repair workshop if its getting annoying.

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didnt you post a thread not that long ago about another problem you were having with your JD at high volumes ? Maybe thats connected in some way.


It could be anything, a dry joint, failing component etc. Might be worth taking to a local repair workshop if its getting annoying.

 

Yeah, an RF problem when its connected to anything...I was considering getting a hum destroyer or noise gate as a temp fix. Ive also considered brining it in for repair, but Im worried the repair will end up costing more than I want to spend. I did pop it open a few weeks ago and the output connectors seems awfully loose..a cold solder joint or bad ground could definitely be the culprit.

 

Id almost rather spring for a JD-990, and then keep the 800 around as a controller, then spend money on repairs...

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Originally posted by Awake77

Id almost rather spring for a JD-990, and then keep the 800 around as a controller, then spend money on repairs...

 

Smart, given that the true sonic power is not achieved until the JD-990 is used.

 

The Juno is to the JD-800 as the Jupiter is to the JD-990. ;)

 

It would be wise to get a Hum-X for the JD-800 - consider that its power lead is not grounded.

 

I always found my JD-800 outs just a little crunchy at low levels, but that was partly because of the relatively poor gain scaling in the algos in the effects section.

 

Is your problem still there if you disable your internal effects?

 

 

wondering,

Ian

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Thanks for the response Ian - its *much* less noticable if I turn the effects off. Can still hear just the tiniest bit of breakup though, if levels are high enough.

 

Its odd, because otherwise the synth sounds just as clean and powerful as it should. There's a parameter in the settings menu for adjusting the D/A converter - I wonder if that could be it? Then again, if that was off you'd think everything would sound wrong.

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I highly doubt that it is RF. My XP-80 used to do the same thing. If I'm not mistaken, it's DAC related. I always found it more pronounced on low sounds that had a long release phase. This seems to happen on everything pre-XV series. The new Roland boxes have nicer converters.

 

The older ones used Burr-Brown PCM converters, and the new ones use Burr-Brown Sigma Delta converters. (which don't require a higher precision output stage) It comes from a discontinuity between the most significant bit, and the next step down. These older DACs can be trimmed to get rid of that noise. The problem is, Roland didn't include trim pots for this, so they could possibly be hacked onto it, but you'd want to find a good tech for that, (unless you're pretty good with this stuff) I imagine all it would take is connecting the right value trim pot to a specific pin, but I'm not entirely sure.

 

The Alesis DM drum modules had this problem as well.

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Ah, thanks J3RK!! That makes sense..there are actually 4 trim pots on the jack board, but as I dont have the service manual Im afraid to touch them, not knowing what they are.

 

Im going to try messing with the D/A settings in the editor tonight, hopefully that will fix something. In the meantime, Im looking for a deal on a JD-990 :)

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Originally posted by Awake77

Ah, thanks J3RK!! That makes sense..there are actually 4 trim pots on the jack board, but as I dont have the service manual Im afraid to touch them, not knowing what they are.


Im going to try messing with the D/A settings in the editor tonight, hopefully that will fix something. In the meantime, Im looking for a deal on a JD-990
:)

 

The 990 will have the same PCM DACs, so I'm pretty sure you'll get the same results. A lot of people don't even notice that sound, and some of them may just be calibrated better in the first place, so a response from one or two users may not be a good indication of whether you'll see the problem or not. It actually took a little while for me to notice that when I had my XP-80, as it wasn't apparent on many of the sounds that I used.

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my JD990 also suffers from the exact same problem. Distortion on the sound as it fades, from both the headphones and main outs. But if you switch off the internal effects it not half as bad..

it must be something that many of these old Roland synths suffer from.

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It actually took a little while for me to notice that when I had my XP-80, as it wasn't apparent on many of the sounds that I used.

 

Same here, the only reason I picked up on was because I was listening intently for the RF 'whine' sound I was trying to fix. Its not really that big of a deal...I guess a noise gate would take care of it.

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So I just got home and went into 'self test' mode on the JD800, it plays a sine wave with the message "Is the Sound Clear?" on the right LCD and "Adjust VR on jack board" on the left.

 

I dont know what that means, perhaps its something to do with the pots Ive seen on the jack board. Ive got to get ahold of the service manual somehow, maybe i can sort this out myself.

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Just an update - cranking the volume and listening to the sine wave, its definitely a tad bit scratchy...looks like this might be an easy fix, hopefully.

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That would be very cool if they allowed you to adjust it yourself. That would just make their coolest PCM synths that much more cool. I hope that's what those adjustments are for. (would be nice to have built-in calibration tools) Let us know if you find something.

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Originally posted by Awake77

So I just got home and went into 'self test' mode on the JD800, it plays a sine wave with the message "Is the Sound Clear?" on the right LCD and "Adjust VR on jack board" on the left.


I dont know what that means, perhaps its something to do with the pots Ive seen on the jack board. Ive got to get ahold of the service manual somehow, maybe i can sort this out myself.

 

 

 

At least, I

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Thanks for the info gilbertopb!! I can definitely handle that. I dont have a scope right now though...looking at Ebay it looks like its about $100 for an inexpensive one shipped. Ive always wanted one though so maybe Ill spring for it.

 

I can hear the low-volume scratchiness on the output test, think its worth adjusting by ear?

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There are some "osciloscope" programs, but remember they only show the wave you are listening to.

 

A technical may probe the components using such equips, but I

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Originally posted by Awake77

Thanks for the info gilbertopb!! I can definitely handle that. I dont have a scope right now though...looking at Ebay it looks like its about $100 for an inexpensive one shipped. Ive always wanted one though so maybe Ill spring for it.

 

Inexpensive scopes are nearly always straight analogue things, to capture a trace of a changing wave and look at it, you're going to need a digital storage scope, perhaps the Tektronix 1002.

 

B>

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Well...good news! I fixed it!! :D

 

Curiosity got the best of me and I couldnt wait a week or more to get a scope, so I popped the JD800 open and hooked it up, cranking the gains on my headphone mixer so I could hear any subtle noises.

 

I rolled the VR1 screw back just a touch, and I could hear the difference in the smoothness of the sine wave. I played with it a little more until it sounded about perfect to my ears, then went back into single mode and tried playing some patches that I knew caused the problem.

 

Dead quiet!! Even with effects up 100% and at max volume. Even nicer, the synth is noticably more crisp after the adjustment.

 

Id still like to get a scope and make sure the converters are adjusted as close to perfect as possible - but I guess for now it can wait.

 

So thanks everyone for looking into it!!! If anyone else runs into the problem, now we know what to do. :D

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Originally posted by gilbertopb


D/A Adjustment

Got a procedure for JD-990 ?

 

I would like to check it out. (Dont worry i got the scope and often do synth repairs). :)

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