Got a Mopho Keyboard and want it to sound better?

Any music gear discussions that don't fit into one of the other forums.

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Synthbuilder
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Post by Synthbuilder »

Skaput wrote:By the way what type of solder did you use for the modification, lead free or the good stuff. Just wondering if it would make much difference.
With my own gear I always use Pb/Sn solder - it's just easier to use especially if I'm moving things on and off several times which I need to do for comparison* purposes. For a customer I'd stick with whatever was used by the manufacturer.

* No wave files for the 'after' comparison from me for a while. I've not got time to do it this week. But dabbing that cap on and off while listening to the output made it perfectly clear it is a worthwhile mod to do.

Tony
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flo
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Post by flo »

Synthbuilder wrote:
flo wrote:Any idea about their other stuff, Tetra etc.?
I've not seen the insides of any of the other stuff or had one to play with long enough to investigate further. I would hope they haven't repeated the same thing.

But just listen to the pulse wave at 99. If it sounds nasty and garbled like the wav file above then it could well have the same noisy DAC reference.

Tony
Will check this on my Tetra and report back...
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widdly
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Post by widdly »

Just did the mod on my mopho and it sounds good. Before with the pwm at 99 it sounded like the sample Tony posted. Now with PWM set at 99 it sounds about the same as when the PWM is set at 1. I used an electrolytic because I didn't have a tantalum.

:tu:
JohnLRice

Post by JohnLRice »

That's awesome, Tony! :yay: :hail:
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pre55ure
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Post by pre55ure »

Wow

I'd love to know if this type of thing is a problem on any of their other boards as well. I have an Evolver that I've always noticed has sort of a weird "extra modulation" happening on the analog waves. I wonder if it might be related to something like this. :hmm:
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computer controlled
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Post by computer controlled »

Huh, i never noticed this before. I don't have a Mopho anymore, but if i end up with one again, i'll most certainly do this. If anyone does this with the desktop, post a pic!
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wavehead
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Post by wavehead »

damn that looks like some serious corner cutting, but i guess anybody mass producing this stuff at "competitive prices" is going to have a hard time not cutting corners.

makes me wonder what else is going on in some of the DSI stuff that might be partly the reason some of their gear gets a bad rep.
dafus
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Post by dafus »

Thank you Tony for this post. I just did it and it definitely sounds much better than before.
At least for the high Pulse range. Not sure it affects other OSC shapes too but it certainly "feels" better. :hihi:
60€-cent for the Tantalum and 15 minutes unscrewing, soldering and screwing it back on - totally worth it!
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brokensolderingiron
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Post by brokensolderingiron »

Synthbuilder wrote:
lvoemachine wrote:This is cool. I forwarded this on to Carson Day at DSI. They might find this kind of interesting.
They already know about it. I've been in contact with them all last week. The support lady was very kind and helpful and has forwarded my e-mails onto the technical department. We'll see what they say but I haven't heard personally back from anyone yet.
Tony
Great find and solution!

Wat's puzzling is despite DSI designed in RC smoothing filters on most CVs and the DAC is 16bit yet PW was rattling that bad and clearly no more within specification of the 16bit DAC rendering to 9 10 bits was fixed to a lot healthier state with a simple cap.
Did DSI fix the Mopho desktop "dead oscillator cycles" that was found on SDIY list 6 years ago?(Most noticeable with bass sounds)
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Karg
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Post by Karg »

Hi,

inspired by Tony's mod, I improved my Mopho Desktop. Sound is much cleaner now! Thanks for sharing your insights!

I also added a USB port, indicator LEDs for clock and notes played, and as a bonus some wooden sides.

Image

Detailed instructions are published on my blog: http://karg-music.blogspot.de/2016/01/m ... hosis.html

, Karg
Ahinga
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Post by Ahinga »

did anyone do this mod with an mopho x4?
i have not opened it yet, but discovered at least 2 dacs on pictures...
catzrcool
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Post by catzrcool »

Great tip on the DAC-filtering, I'll have to get around to doing it on my Mopho. But is there any technical reason to use a tantalum cap?

The thing is, there are some pretty strong ethical reasons to forego tantalum whenever possible, it's mined under horrible conditions and the ecological impact is bad.

One poster mentioned that he used a regular cap, if that works the same, that's what I'll do, and that's what should be recommended imo.
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Synthbuilder
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Post by Synthbuilder »

catzrcool wrote:But is there any technical reason to use a tantalum cap?
None at all. You can use any decent quality electrolytic too. I just used tantalum because I had a bag full at the time. One good thing about them is they do have a resin case which makes it less likely to melt when soldering them - which is quite easy to do when soldering the device from the topside of the board.

Tony
catzrcool
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Post by catzrcool »

Allright, thanks a lot for the help!
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Karg
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Post by Karg »

While I do not have a Mopho 4x, in the Tetr4 it is also two DACs. Each of them covering two voices. Here the mod works equally well.

Locations are the following:
Image

Text description is posted elsewhere: http://karg-music.blogspot.de/2016/06/t ... hosis.html

, Karg
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50quidsoundboy
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Post by 50quidsoundboy »

yeah but character
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1986Bowler
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Post by 1986Bowler »

I think I may end up modding mine as well.
Got both the Mopho and the Tetr4.
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