VOGONS


First post, by Apolonius

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Hello.

Since the MT-32 is really expensive to buy today, I have seen the possibility to buy a RA-50, RA-90 or RA-95 for 100€ or below. Are these modules == real MT-32?, because I have a SC-55 and don't want another device "compatible" with MT-32 but with the same result as SC-55.

Regards.

Reply 1 of 24, by cyclone3d

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Real MT-32 but you have to use SoftMPU with them because they don't support the All Notes Off command.

I just received one a couple days ago but haven't had a chance to hook it up and test.

I suspect that the output might be cleaner than a stock MT-32. I will do a comparison when I have time.. probably in the next few days.

The only downside is that you don't get the nice text output from games like you would on a real MT-32.

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Reply 2 of 24, by derSammler

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The RA-50 is a real CM-32 with the addition of an arranger (it's hence fully MT-32 compatible), the others aren't. When buying a RA-50 instead of an MT-32, you only have to live with two restrictions: 1. games can not send text to the display (obviously, as the CM-32 has no display and that's what the RA-50 is). 2. "all notes off" is not supported. SoftMPU has dedicated support for the RA-50 and will emulate this, so no big deal.

Reply 3 of 24, by Apolonius

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Thanks guys.

I can live without the text on the screen, really it doesn't matter. And the use of SoftMPU is a must for me because I'll use this module on a "modern" PC and if I can on a Thin Client based on native DOS so, hardMPU for me is not useful.
So, I go to buy the RA-50 today and hope that on next week I'll can play as a child with a new toy 😀

And... a very last thing, with this module all the games that uses MT-32 or LAPC sounds perfect?, can I save the purchase of a CM-32L too?

Regards.

Reply 4 of 24, by derSammler

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There's no difference in sound to a 2nd generation MT-32, as it uses the exact same chips. The ROM is the same as in the CM-32L (it's even labeled this way), but I'm not sure about the additional sound effects that the CM-32L offers. Some say they are not accessible on the RA-50, others say they are there but of lower quality. No idea, really. Did not test a game yet that uses them.

Reply 5 of 24, by Apolonius

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derSammler wrote on 2020-06-10, 17:07:

There's no difference in sound to a 2nd generation MT-32, as it uses the exact same chips. The ROM is the same as in the CM-32L (it's even labeled this way), but I'm not sure about the additional sound effects that the CM-32L offers. Some say they are not accessible on the RA-50, others say they are there but of lower quality. No idea, really. Did not test a game yet that uses them.

Thanks, I'll buy in any case and test when I can.
But I hope that @cyclone3d will can test first and wrote some notes here 😀

Regards.

Reply 6 of 24, by ras2a

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How did you get on with your newly purchased RA-50 and did you confirm if the additional sound effects were present in the machine?

I’m also considering getting one as they are considering cheaper than 2nd hand MT-32’s

Thank you

Reply 7 of 24, by Salient

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ras2a wrote on 2020-06-16, 23:55:

How did you get on with your newly purchased RA-50 and did you confirm if the additional sound effects were present in the machine?

I’m also considering getting one as they are considering cheaper than 2nd hand MT-32’s

Thank you

I recently bought one, and as far as i am aware it does not have the extra sound effects that the CM-32L has. it is 'just' an second generation MT-32 in that respect, but A LOT cheaper 😀

Don't like the display that much though... too 'generic'.. 😀
I have a spare green LCD laying around that originates from a Roland D-10 and I am going to try to see if I can get that working in the RA-50, should be looking nice.

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Reply 8 of 24, by Apolonius

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ras2a wrote on 2020-06-16, 23:55:

How did you get on with your newly purchased RA-50 and did you confirm if the additional sound effects were present in the machine?

I’m also considering getting one as they are considering cheaper than 2nd hand MT-32’s

Thank you

Hi, finally I have bought a MT-32, for a bit more money so, I can't help you.

Regards.

Reply 9 of 24, by Salient

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Salient wrote on 2020-06-17, 05:03:

I have a spare green LCD laying around that originates from a Roland D-10 and I am going to try to see if I can get that working in the RA-50, should be looking nice.

Success 😀

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Reply 10 of 24, by darry

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I wonder if these are similar enough to an MT32 gen 2 that you could swap in the Ctrl ROM from an actual one . Who cares if arranger functions and screen don't work if MIDI in and audio out still do , and if it fixes all notes off .

I should be getting mine Thursday or Friday . Seller kindly offered to deliver it in person .

EDIT: Would guess that nothing is socketed in these, though .

Reply 11 of 24, by Cloudschatze

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The filtering of the All Notes Off message in the RA-50 occurs in the arranger section, which all MIDI input passes through. The sound section uses an actual CM-32L control ROM (despite having just half of the PCM ROM). The socketed, v1.00 EPROM is visible in Salient's photo, where one of my RA-50s uses a soldered-in, v1.02 mask ROM, by comparison.

I haven't seen the RA-50 service notes, but perhaps there is some hidden means of defeating the message filtering. Outside of that, cutting a single trace and running a bodge wire from pin 1 of IC43 to pin 1 of IC28 might be an acceptable hardware workaround. I have a sacrificial RA-50 that I can test this idea with.

Reply 12 of 24, by darry

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Cloudschatze wrote on 2020-06-17, 22:56:

The filtering of the All Notes Off message in the RA-50 occurs in the arranger section, which all MIDI input passes through. The sound section uses an actual CM-32L control ROM (despite having just half of the PCM ROM). The socketed, v1.00 EPROM is visible in Salient's photo, where one of my RA-50s uses a soldered-in, v1.02 mask ROM, by comparison.

I haven't seen the RA-50 service notes, but perhaps there is some hidden means of defeating the message filtering. Outside of that, cutting a single trace and running a bodge wire from pin 1 of IC43 to pin 1 of IC28 might be an acceptable hardware workaround. I have a sacrificial RA-50 that I can test this idea with.

Hopefully you will be able to reverse this mod attempt if it does not yield expected results . Please let us know if you decide to try it .

On another note (pardon the pun), if the PCM control ROM is the same as that of CM32L, what would be the chances of successfully replacing the PCM ROM with that of a CM32L, in your opinion ?

Reply 13 of 24, by Cloudschatze

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darry wrote on 2020-06-17, 23:25:

... what would be the chances of successfully replacing the PCM ROM with that of a CM32L, in your opinion ?

It's not so much a matter of replacement; rather, the additional PCM ROM chip found in the CM-32L, et al., would need to be added. I can't comment on how easily that can be done, I'm afraid, but I'm sure it's possible with some effort.

Reply 14 of 24, by Cloudschatze

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Cloudschatze wrote on 2020-06-17, 22:56:

... cutting a single trace and running a bodge wire from pin 1 of IC43 to pin 1 of IC28 might be an acceptable hardware workaround. I have a sacrificial RA-50 that I can test this idea with.

Alright, so this does indeed work. The All Notes Off is now recognized as expected, and the volume knob continues to function, which I'd hoped would be the case. One amusing side-effect is that, when powering-up, an "LA Sound module is not present !" error message is now displayed.

Reply 15 of 24, by darry

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Cloudschatze wrote on 2020-06-18, 03:01:
Cloudschatze wrote on 2020-06-17, 22:56:

... cutting a single trace and running a bodge wire from pin 1 of IC43 to pin 1 of IC28 might be an acceptable hardware workaround. I have a sacrificial RA-50 that I can test this idea with.

Alright, so this does indeed work. The All Notes Off is now recognized as expected, and the volume knob continues to function, which I'd hoped would be the case. One amusing side-effect is that, when powering-up, an "LA Sound module is not present !" error message is now displayed.

Thank you . I might actually do that, if my crappy soldering skills allow .

Reply 16 of 24, by Salient

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Which trace exactly had to be cut?

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Reply 17 of 24, by Cloudschatze

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Salient wrote on 2020-06-18, 19:34:

Which trace exactly had to be cut?

So, this isn't gospel or anything, but:
ra50_s.jpg

Do note that only the MIDI output from the arranger section to the LA sound section is affected by cutting that trace. The arranger will continue to receive data from either MIDI input, and can yet be used to drive an external synth, if desired.

Here's a quick, dumb video as well:
https://youtu.be/5KSqa5ddP_E

Reply 18 of 24, by darry

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Cloudschatze wrote on 2020-06-20, 01:06:
So, this isn't gospel or anything, but: https://www.symphoniae.com/misc/vogons/ra50_s.jpg […]
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Salient wrote on 2020-06-18, 19:34:

Which trace exactly had to be cut?

So, this isn't gospel or anything, but:
ra50_s.jpg

Do note that only the MIDI output from the arranger section to the LA sound section is affected by cutting that trace. The arranger will continue to receive data from either MIDI input, and can yet be used to drive an external synth, if desired.

Here's a quick, dumb video as well:
https://youtu.be/5KSqa5ddP_E

Cool, thank you . I was expecting the ICs to be surface mount and require soldering to nearby VIAs . This is much simpler than I expected .

Reply 19 of 24, by Salient

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Cloudschatze wrote on 2020-06-20, 01:06:

So, this isn't gospel or anything, but:

Do note that only the MIDI output from the arranger section to the LA sound section is affected by cutting that trace. The arranger will continue to receive data from either MIDI input, and can yet be used to drive an external synth, if desired.

Thanks!
I am going to try to make this switchable so I can use it as a true MT-32 for DOS or as the arranger it was intended to be 😀

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