MT-32 2nd gen vs CM-32L?

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MT-32 2nd gen vs CM-32L?

Postby Spikey » 2017-7-19 @ 04:44

Hey folks,

This has been covered before, but I can't remember- are these two identical, except for the CM-32L/LAPC-I's extra sound effects? As in, fidelity, circuitry, etc.

For example, with Larry 5 even without the extra CM effects, instruments still sound different on a first gen MT-32 versus the CM- for example BellSinger.
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Re: MT-32 2nd gen vs CM-32L?

Postby sergm » 2017-7-19 @ 09:59

AFAICT, all of the quirks of old MT-32 we emulate in munt were absent when I tested with control ROM image v. 2.04. As for the circuitry, I can check with the service notes (in the evening, I hope). But evidently, I have nothing to say about fidelity ;)

One thing to note, new MT-32 has demo songs and CM-32L / LAPC-I doesn't lol
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Re: MT-32 2nd gen vs CM-32L?

Postby Cloudschatze » 2017-7-19 @ 15:10

Spikey wrote:This has been covered before, but I can't remember- are these two identical, except for the CM-32L/LAPC-I's extra sound effects? As in, fidelity, circuitry, etc.

There's a difference in the hardware volume control implementations of the v2.x MT-32 and CM-32L, but I don't find that to be of much consequence as far as fidelity is concerned. If not exactly identical, they sound similar enough to me.

Other issues aside, I find that the overall sound quality of the DTM LA devices increases in relation to the hardware generation:

Generation 1 - v1.x MT-32
Generation 2 - v2.x MT-32, CM-32L, CM-64, LAPC-I
Generation 3 - CM-32LN, CM-500, LAPC-N

There are also other component factors to consider. I recall commenting that the particular v2.x MT-32 I'd sent you sounded "better" than the other v2.x MT-32s that I had, and attributed that to a difference in the op-amps used.
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Re: MT-32 2nd gen vs CM-32L?

Postby Spikey » 2017-7-19 @ 15:26

Yeah, I mean the new type MT-32 versus the CM :)
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Re: MT-32 2nd gen vs CM-32L?

Postby sergm » 2017-7-19 @ 15:38

As I can see, the exactly VCA circuitry (as per the schematic) is identical. But right, the output amplifiers after the VCA are a bit different. Seems, the LPF implementation and the reverb are also identical. And obviously, there are differences in routing the PCM ROMs as there are two in CM-32L. ;)

Anyway, I think new MT-32 differs from the old one much more than from CM-32L.
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Re: MT-32 2nd gen vs CM-32L?

Postby Cloudschatze » 2017-7-19 @ 15:58

I've taken to referring to the "new type" MT-32 as either the v2.x or v2.xx MT-32. It makes more sense, while still being correct. Just know that the "new type" MT-32 is what is being referred to in such statements.
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Re: MT-32 2nd gen vs CM-32L?

Postby Spikey » 2017-7-20 @ 08:24

Other issues aside, I find that the overall sound quality of the DTM LA devices increases in relation to the hardware generation:

Very interesting. Thanks for the information. How big a difference is there between 2 and 3?
Thanks again for that 2nd gen you sent me. It has been very helpful over the years :)


From what I remember Serge, the IC's used were different? I forget the technical details. Something like 13 or 14 bit sound versus 16 bit, also.


OK, I am going to pose a much more specific question. The game Larry 5, which was composed using a CM-32L (to the best of our knowledge). If one recorded its' output on a 2nd gen MT-32 and a CM-32L device, would the output be identical, aside from any CM-exclusive sound effects that may be present?
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Re: MT-32 2nd gen vs CM-32L?

Postby sergm » 2017-7-21 @ 06:48

Spikey wrote:From what I remember Serge, the IC's used were different? I forget the technical details. Something like 13 or 14 bit sound versus 16 bit, also.


Unfortunately, none of MT-32 compatible modules produce 16 bit sound. Well, there is a ton of differences between the "old" and the "new" MT-32, in fact. But I'd better shut up and redirect you to Wikipedia ;)

OK, I am going to pose a much more specific question. The game Larry 5, which was composed using a CM-32L (to the best of our knowledge). If one recorded its' output on a 2nd gen MT-32 and a CM-32L device, would the output be identical, aside from any CM-exclusive sound effects that may be present?


If nit-picking, of course, you'll get output somewhat different, since we can only reliably compare digital captures. After all these years, real modules really start sounding quite differently (not mentioning those differences in the schematic we told above). But if we compared digital captures, I'm pretty sure they would be nearly identical for the MT-32 supported timbres. Again, even digital captures are never 100% identical because of non-deterministic factors that affect synthesis (e.g. MCU-LA32 interrupt times, reverb noise, etc.). For example, the attached two captures are slightly different though sound similar.

As for the PCM waves, the lower PCM bank of CM-32L is bit-identical to the MT-32 PCM ROM. All the PCM wave definitions and related timbres are also identical in the control ROM tables. So, the differences in sounding are ought to be very minor.
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Re: MT-32 2nd gen vs CM-32L?

Postby sergm » 2017-7-25 @ 08:38

BTW, I've added mapping for Control ROM v2.04 so munt recognises it now. Indeed, it's much like the CM-32L/LAPC-I ROM internally, so if one has also a latter device, there's a little point to use the ROM from the former.

Cloudschatze, could you help with making mappings for more ROMs in the 2.x series? Or is there no sense to bother?
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Re: MT-32 2nd gen vs CM-32L?

Postby Cloudschatze » 2017-8-12 @ 02:08

sergm wrote:Cloudschatze, could you help with making mappings for more ROMs in the 2.x series? Or is there no sense to bother?

I can dump 2.07 just as soon as I obtain a ROM programmer. I think it's worth the bother. There's at least one bug/annoyance fixed in version 2.06 that I've personally experienced with a 2.04 unit.
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