MIDI performance on a Macintosh Classic, good?

[Man-Machine]

Because MIDI latency and jitter on modern computers is a problem. I've been contemplating in either get a dedicated hardware MIDI sequencer or an old Mac for MIDI sequencing, so I have some questions for you guys:

1) Would an old Mac perform just as good as any hardware MIDI sequencers?

2) Would a Macintosh Classic have enough power to properly sequence MIDI? (I already have an old one in the closet)

3) If so, what's a good MIDI software to go with it that it won't impose a lot of strain and cause latency and jitter that I'm trying to avoid?

Thanks!

 

[Mac128]

You will be limited to the number of tracks you can run on a Classic. Performer is the best of the lot in those days. But you will run into the same problem if try to jam too much into the tracks or assign too many patches. Not sure what you are running now, but I can't imagine you'd have those problems on a modern Intel Mac unless you are just maxing out the tracks in which case, a Classic won't be a good answer for you.

 

[Man-Machine]

I want to get down to a couple of ms of MIDI jitter. So far I'm at about 5ms with my computer setup. I'm now only recording simple note on/off events to make sure nothing is clogging up the pipe.

I know the MIDI protocol is flawed with regards to latency/jitter. So, at best, would the hardware MIDI sequencer option be more stable than an old Mac?

 

[Bunsen]

Hardware sequencers are pretty tight, it's true. What model/s are you considering? If you want to keep computer-style sequencing as an option, have you considered an Atari 540 or 1040? They're supposed to have rock-solid timing. And woo, built-in MIDI ports

 

[Scott Baret]

If it's simple enough and you have the software and necessary hardware, a Classic should be fine, but if you want to do something a little more complicated, you may want to consider a Classic II or SE/30 (if you want to stick with compact Macs). Also, bear in mind that the original Classic does not have stereo sound output (if this is important to you). The SE/30 and Classic II are the only monochrome compacts that offer stereo output.

You may not be able to reach the complexity of today's electronic artists, but you should be able to make something at least as polished as Depeche Mode from the very early 1980s (back when synthpop was a novelty).

 

[Bunsen]

MIDI =/= sound.

Depeche Mode used a BBC Micro !

Another to consider if you like building things: the phenomenal MIDIBox SEQ

 

[H3NRY]

Just how little jitter can MIDI deliver? At 31.25 kb/s, or 31 bits/mS, and 3 bytes (30 bits with start & stop bits)/shortest MIDI message, it seems you need at least 1 mS per event. Longer for more complex events. Can any sequencer reach 2 mS jitter?

In practical terms, I've played complex sequences on a 512K Mac without audible problems, but then I doubt I can discern 5 mS timing variances.

 

[Bunsen]

The Midibox sequencer's response time is measured in nanoseconds. Of course, as you point out, MIDI is a serial protocol and very low bandwidth, so there is a limit to the timing accuracy of supposedly simultaneous events on a single port*. If you are using a multi-port MIDI adapter, it should in theory be possible to have much tighter timing between events on different ports.

*NB: not MIDI channel. There are 16 logical MIDI channels per physical MIDI port/bitstream.

I expect that a Classic should have little trouble being as timing-accurate as a single MIDI port is capable of.

 

[Mac128]

Good point Bunsen. There was some software that allowed one to use both serial ports. This is exactly why the PowerBook 100 had a modem port replacement serial port, as many musicians found the 100 to be the perfect portable stage Mac.

 

[Bunsen]

Even on a single serial port, you can run an adapter with three MIDI OUT ports. That said, I assume timing accuracy between ports would be restricted by the serial bandwidth between the Mac and the adapter, so using two serial ports would be even better. Whether it would be noticeably better is another question altogether.

 

[H3NRY]

The typical 3-port MIDI adapter (that is 3 MIDI outs on the same 16 channels) is merely a 1 MHz crystal to provide the clock for the Mac's SCC chip to generate 31.25 kilobaud and some DIN jacks. These are limited by MIDI's slow serial rate. There are "32 channel" adapters that use both ports, and can issue simultaneous events if the Mac's MIDI sequencer has sufficiently tight timing. Then there are the adapters which contain their own CPUs and multiple MIDI serial ports such as the Opcode Studio 64 and the MOTU MIDI Express. The latter communicate with the host Mac at a higher baud rate, like 115 or 230 Kbaud, so should have tighter timing possible between channels. In actual practice I don't know what the timing accuracy is, since it depends on routing and processing within the interface box.

In the practice of acoustics, it is generally assumed that sounds are perceived as simultaneous if they are within 25 mS of each other. Much more than 25 mS apart we hear an echo or arpeggio.

In practice, driving 3 synths from Vision running on a 512K Mac with a simple MIDI adapter, I haven't noticed any problems unless I let something like pitch bend data clog the channels. I suspect MIDI performance on a Classic will be fine, though it's hard to predict whether it can hold <2mS jitter. Too many variables, and 2mS is about 10X the accuracy most folks can hear.

 

[Interceptor2]

I know this thread is now somewhat old. I have an Atari ST 1040 with Sequencer One Plus (now free) and that is the tightest to date.

It has two issue that get me, one is it sends a bunch of sysex commands when the "stop" key is pressed, which at the time of programming were harmless but it causes my new synth to go potty, its controller commands now which can't be switched off (I've even spoken with the orginal programmer). And it's possilble to have hanging notes if sections (bars) are deleted. Otherwise a stunning little sequencer.

I also use the sequencer built into my Ensoniq keyboards, tight but a different musical experince to the ST. My XP/Cakewalk just doesn't seems as "tight" to my ears, but I'm not going to pretend to be some great musician.

I'm planning to get one of my old Macs sequencing to see if they are as tight as the ST.