CM32L plus midi messages from MT-32?

[Nagra]

Evening folks,

today was a lucky day. I won a CM32L on ebay. Cant wait to hear the water bubbling in Ultima Underworld again :-)

In the mid 90s my LAPC-I died so I had to switch completely to my SB Pro in order to hear music as well as sound effects.
I remember how dissapointed I was listening to the poor soundblaster music. That day I gave up UU without ever finishing it.


Well that was in 1996 or so and now over a decade later I am equipped with an SCC1 and an MT32. Is it possible to use the midi throu (?) connection to listen to the cm32L and to get the MT32s midi-messages as well?

If so, how do I connect the external devices? Do I just need one additional midi cable?

Thanks in advance

[Rhizome]

Hehe, I've done this before. Simply use a standard MIDI cable from the MT-32's "MIDI-Thru" and into the CM-32L's "MIDI-In". Plug the MIDI cable from the computer into the MT-32's "MIDI-In". Remove the audio cables from the MT-32 and keep them in the CM-32L.

Play away 

[Nagra]

Thanks Rhizome, I already thought in that direction but wasn´t completely sure how to connect the external devices.

Play away 

I definately will :-)

[Nagra]

Hi folks,

so, my CM32L has arrived today. After some cleaning it looks pretty nice again.

Unfortunately it did not come with the original poweradaptor. The one I got here says:
9V, 500 mAh 4,5 VA. The CM32L demands 600 mAh.

Do I risk damaging the module when using this non-original adaptor? It is the one that what was shown on the ebay photo. So I assume that the former owner had no problems with that configuration. I already sent him a mail.

Any thoughts? I will go for a standard midi cable this afternoon. And in the evening there will be a celebration here :-)

greetings
nagra

[Alistair]

Lower is bad, I had problems with my MT-32 running it on less than it needed.

AC adaptors aren't so expensive anyway- not worth the risk. More the point, it will get very hot and inefficient very fast.

- Alistair

[Rhizome]

I still run my Yamaha MU10 on a 7V (should have 9V) power adapter and it works perfectly fine. From what I've learnt, under-powering a device doesn't damage it but could actually make it last longer (that's where under-volting CPUs comes from).

As long as the CM-32L plays fine and doesn't lose any sysex data over a period of time, I'm sure the only thing more likely to break is the AC adapter 

[Tom]

I've done the under-powering thing, too, with a MT-32.  Never had a problem and it worked fine.

[Nagra]

Party is over now. Time for bed :-)

But at first it took me some time to enjoy the new device here.

It seemed that the under-powering had a negativ effect to the cm-32l. I heard absolutely - nothing! When turned on, only the red power lamp gave me a feedback.
I was shocked and thought of DOA. But then I tried the original power adaptor that came with the MT-32 (650 mAh = over-powering!) and BOOM the green midi message light turned on as well and the device worked perfectly from that moment on. Strange huh?

I must say that the adaptors plug is a little bend. Couldn´t plug it in at first. But I got the red power-on light of the cm-32l so I don´t think that the adaptor isn´t working.

The former owner told me that the cm32l worked fine with that adaptor, hmm.



 

[Rhizome]

The former owner told me that the cm32l worked fine with that adaptor, hmm.

Never trust an eBay seller - that's what I've learnt 

[haradan]

Although I'm no expert in this field, I know volts and amperes are two very different things. You may undervolt a unit without risk of damage and it may actually work if the volt difference is not very high (like 9 volts vs 7 volts) but you should never underampere a unit (I know that's not a real word, but you get the idea). On the ampere side, your power adaptor should always have more amperes than your unit or it won't work (The unit will not be receiving enough "power", so to speak). It doesn't matter if it has 1000 mA, the unit will use only the 600 mA than it needs.

And of course, never overvolt a unit, that will fry it almost for sure.

[Nagra]

I only want to bring this to an end here:

After a quick search at home I found an old AC-adaptor with a switch for multiple Volt-options. I set i to 9 volts, connected it to the cm-32l and it worked like a charm.
After that I connected the two external devices with a standard midi cable and I now got the beloved midi-messages as well. Now everything is just the way I wanted it to be.

And there it was again - this timemachine-feeling. Playing the old games with the midi-hardware of that time. Somehow nothing hast changed.

[mace]

haradan, you're absolutely right.

We all remember Ohms law right? 

Current (Ampere) multiplied by electrical tension (Volt) equals Power (Watt)

So when you undervolt a device, it simply draws more current.

Consequently, you can "undercurrent" a device, but then it needs more volts.
This is because the power usage in watts will be the same.
(This is not really how it works, because a device usually only draws the current it needs, notable exceptions are LED's and Fluorescent tubes needing a inductive ballast to limit the current i.e. a resistor.)

Everything is within limits of course, you can't run your MT-32 at 1000 volts of course

For instance my MT-32 has a ACB-220 power supply. This delivers 1200mA, or 1,2 Amps at 9 volts.
For the sake of argument lets say that the MT-32 actually needs all that power to function, that would mean it uses 9 x 1,2 = 10,8 watts.

So if you run it at 7 volts, it will need 10,8 / 7 = about 1,6 amps.
Consequently, if it gets 12 volts (which is not recommended) it will draw only 10,8 / 12 = 0,9 amps

Now because electrical components are rated to a certain maximum voltage you can't go overboard with this, but usually you have a 10% margin, and sometimes more.
But as you can imagine its safer to try to undervolt something than to overvolt something.

Here endeth the lesson.