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Archive for April, 2012

20
Apr

Speakers and shipping…don’t mix

I ordered some replacement speakers for my PA boxes. Two 400watt cast aluminum speakers that arrived today. By courier. FedEx.

Now I’ve always had fabulous service from Fedex and they’ve delivered some fragile stuff before, but this time, I have to give them a fail. My first big clue was the outside of the box. Looks like the baker tried to crawl out of the cake…

Box_Outside

When I unpacked the speaker, well, it was obvious that cast has no give to it at all. At least I don’t think the frame is supposed to look like this…

Broken_Woofer

The second woofer had some edge damage. I didn’t even bother plugging it in to see if it affected the sound. It’s not right, it needs to be fixed. The broken frame one needs to be replaced.

Cone Damage

Kind of puts a damper on the day when I was going to swap out the speakers. On the brighter side, I played the best round of golf I ever played. Shot +1 (73) on the NorthView Canal.

11
Apr

MIDI Muddy Murky

Working with MIDI interfaces for, oh, 20+ years now, has always been an interesting experience. Interesting in the fact that sometimes they work perfectly from the get go, and other times you feel like you need to beat them into submission with a sledge hammer.

Standard interfaces come from a variety of sources from Roland, M-Audio and there’s a lot of them used as “add on’s” to audio interfaces. While 99.9% of these work for standard 3 byte MIDI, there’s another portion of MIDI, called SYSEX that will tax these interfaces to the limit.

What is SYSEX? Essentially it’s a way for a company to write their own protocols for the device so a custom message can do anything they want it to do. A message can be anywhere from 6 bytes to thousands of bytes in length. It’s actually a slick idea, but never quite implemented fully. By that I mean, there’s no or little error checking done on the message received to verify that it was sent perfectly. I.e. no checksums, CRC’s or anything. Which would have been simple to implement, but never done. As it turns out, the streams, for the most part are very reliable.

Depending on the interface, every one that I’ve tested will receive these SYSEX messages just fine. It’s the SEND that they crap out on.

Enter in the “budget” USB to MIDI interfaces coming out of Asia. These $5 wonders, sometimes work. Sometimes don’t. I’ve got a few of these for testing and without exception, almost every one of them will fail a loopback test. But they will send and receive SYSEX so long as there is a slight delay between the messages. Which tells me the interfaces are not able to do two things at the same time. Obviously the chip designers can’t walk and chew noodles at the same time.

I don’t expect much for $5, but these little beasts do work to a point (high latency):

IMG_2986

Ripping one apart you find this:

IMG_2984

And from the component side:

IMG_2985  

Lots of missing parts on the board (transistors, resistors) so all you can see is an opto-isolator, crystal, transistor, caps, resistors. All SMT. The main chip that performs the “magic” is a USB to MIDI dedicated chip from Asia: MFM0860. Try finding a data sheet on that part.

Not sure what all the MISSING parts might do, maybe send morse code or something unique. Who knows. The thing probably doubles as a Mr Coffee timer/controller.

Thus as I said, and I left off the glowing sugarcoated review treatment these things attract, the odds of these working with SYSEX is roughly the same as winning on the first pull of the slot machine handle…Personally the best part I find to use are the preformed cables. Now those are worth $5.

4
Apr

Bed Day 1

My daughter asked me to build a bed for the grand daughter so…I started with this today…

Keira Bed Wood

5 Hrs later I got it to this point. No top, just the foot board done…

Footboard No Top