Roland JX-8P sound problem

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JackQ90
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Roland JX-8P sound problem

Post by JackQ90 » Wed Dec 10, 2014 11:49 pm

Hey guys,
This is my first post so I'll welcome myself.
Good, now that it's done, I have a question for the community. I looked a lot on forums and websites but I couldn't get the info I was looking for.
I bought a JX8p with the PG800 last week. It sounded good when I tried it, but it was through monitors and when I got home, I noticed how the sound was noisy and thin. I think the synth didnt like the trip home...
The output is not very loud, but it tends to distort quite easily. I tried to move the LMH switch at the back with some contact cleaner. Nothing changed.
The sound is exactly the same out of the headphones output or the L/R.
The other thing is the first/second octave is very quiet. On some presets, where the bass is supposed to shine with rich and fat sound, it's almost unaudible. I looked at some of the video with the preset sounds without any EQ or effects, and it's miles beyond what my synth can do. The first preset, piano 1, is barely useable and the sound is shitty as h**l.
I tried to record it with a compressor (Strymon ob1), delay (Moog mf-104m) and reverb (Tc Hall of fame), but nothing gives me satisfaction. EQing doesnt change much, but a denoizer seems to help a bit. Anyway, I think it's supposed to sound good without any effects.

Do you guys think I could do something with that? I didnt find any ressource concerning this very problem. I'm not very good at electronics, but I have some electrical knowledge. My guess is that the problem is at the output of the circuitry, or there might be one (or 2?) faulty chip for the low oscillators.

Any help is welcome!
Thanks

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gs
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Re: Roland JX-8P sound problem

Post by gs » Thu Dec 11, 2014 6:52 pm

The op-amps may need replacing (they are known to sometimes fail on these old synths).

I had a JX-10 (two JX8P's in one, w/76-note keybed) with the PG-800 programmer a while back... nice combination. I never really gelled with its filters, though.
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Re: Roland JX-8P sound problem

Post by Bitexion » Thu Dec 11, 2014 7:16 pm

Problem with these old analog-digital hybrids is that they used special-made chips that you can't get hold of anymore.
And 30+ year old electronics eventually break. My SQ-80 is pretty wonky sometimes and other times it works perfectly fine.

Kind of avoided vintage synths for that reason the past 6-7 years. There is alot of new synths that are more worth it tbh..no fun buying some old analog giant then have it break after 3 weeks and nowhere to get it fixed in Norway.

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Re: Roland JX-8P sound problem

Post by synthparts » Thu Dec 11, 2014 8:07 pm

Bitexion wrote:Problem with these old analog-digital hybrids is that they used special-made chips that you can't get hold of anymore.
And 30+ year old electronics eventually break. My SQ-80 is pretty wonky sometimes and other times it works perfectly fine.

Kind of avoided vintage synths for that reason the past 6-7 years. There is alot of new synths that are more worth it tbh..no fun buying some old analog giant then have it break after 3 weeks and nowhere to get it fixed in Norway.

Actually I have every chip used In the JX-8P available...

At least most vintage synths can be repaired by the average person with electronics knowledge and soldering skills and schematics are easy to find. The newer stuff is made of cheap Chinese parts and mostly complete board swap/throw away when in breaks.
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gs
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Re: Roland JX-8P sound problem

Post by gs » Thu Dec 11, 2014 10:22 pm

synthparts wrote:Actually I have every chip used In the JX-8P available...

At least most vintage synths can be repaired by the average person with electronics knowledge and soldering skills and schematics are easy to find. The newer stuff is made of cheap Chinese parts and mostly complete board swap/throw away when in breaks.
For old 70s analogs, this may be the case - but most 80s synths (even the analog/digital hybrids) used custom chips for the OSC, VCF, and VCA - sometimes all 3 combined into one chip. And there are sometimes other custom chips that do other functions. h**l, even Dave Smith had a hard time re-sourcing old Curtis VCF chips, so he had to have a new batch made up for his current line of DSI synths.

But if you have already sourced the Roland chips (and the correct ones for this synth), then you are good to go. You only need to put in some time doing the soldering, or send it to a technician for repair.
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Re: Roland JX-8P sound problem

Post by drawtippy » Thu Dec 11, 2014 11:12 pm

There is something wrong with your JX for sure. I have one (with the programer) and it sounds great.

The good news is the PG800 is worth more than the synth and it may be easier to just locate another cheap 8P than to pay for chips and tech work.

Sure, some of the presets are a bit thin but you should be able to make deep basses, warm pads and of course if the "Final Countdown Horns" preset doesn't sound like the record? …yeah it's messed up!
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Re: Roland JX-8P sound problem

Post by Ashe37 » Fri Dec 12, 2014 8:03 am

gs wrote:
For old 70s analogs, this may be the case - but most 80s synths (even the analog/digital hybrids) used custom chips for the OSC, VCF, and VCA - sometimes all 3 combined into one chip. And there are sometimes other custom chips that do other functions. h**l, even Dave Smith had a hard time re-sourcing old Curtis VCF chips, so he had to have a new batch made up for his current line of DSI synths.
The 'Dave Smith had trouble re-sourcing' thing is so often repeated it is probably almost urban legend status now.

On-chip Systems- what used to be CEM- could *not* simply just remake even their old 3394 chips. They needed to be RoHS compliant, which often requires a new chip design, in order to be sold in the EU. Also, their processes might have changed, so the old masks used for etching the chips, if they even have them, may not be usable anymore. He also may have *wanted* a newer chip so that they could put in new features...

Sorry to me this is almost like people saying 'Dave Smith couldn't source the Z80 CPUs used in the Prophet 5 or the Motorola 68000 used in the Prophet VS, so they were forced to use these Analog Devices chips'.

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Re: Roland JX-8P sound problem

Post by JackQ90 » Fri Dec 12, 2014 2:33 pm

I called my tech and he has 1 or 2 more Jx-8p only for parts, so I guess I'll be fine! I'll get back to you when the job will be done!

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Re: Roland JX-8P sound problem

Post by mharris80 » Fri Dec 12, 2014 3:18 pm

Good to hear your tech can get it sorted out. Mine has been acting up lately, too. Bad clipping in the output, and now the chorus is making the distinctive LFO noise. :evil: I know the chorus problem seems to be rather common (my MKS has been doing the same thing). Is it just a matter of replacing the BBD chip, or is there more to it than that?

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