Never been one to let the carrier drop

all of my experimenting with XLR matching transformers is not completely wasted. I did figure out this one really neat trick which has elimited the annoying hum and computer noise in my computer speakers.

(I should mention that my computer speakers are a pair of Mackie SRM450s with balanced inputs, and that most of this does not apply to you normal consumer-type people)

Take two XLR -> 1/4″ matching transformers (currently $15 at a guitar center near you), plug them into each other using a 1/4″ F-F adapter ($4), and add a XLR male-male to one of them ($8). Now what you have is a single-channel isolation transformer! Perfect for when you have to run the PA off four different wall sockets in order to get enough power to avoid opening breakers when you start feelin’ the bass. Add heatshrink to the transformer -> F-F -> transformer part, and you have a very useful generic adapter to keep in your adapter kit. Probably a good idea to keep two or three of them around.

Also, when running Mackies off unbalanced outputs that may have less than perfect grounds, a single isolation transformer plugged into a RCA-m->1/4″-f adapter (assuming you’re dealing with a RCA out) will improve the situation mightily. Very useful for ‘booth’ speakers when the power supply is noisy (and, at raves-^H^H^H^H^Hparties, they always are).

the ‘metal can’ RCA -> XLR adapter combined with a ‘official’ SPDIF cable reduced drasticly, but did not eliminate, the noise. I take this as a encouraging sign that what I have is in fact a signal degradation issue rather than a protocol incompatibility.

One thing that I really don’t understand is why a 25-ohm impedence mismatch is giving me this much trouble? Of course, the other thing is I’m driving a unbalanced signal with a common-mode ground into a balanced input, which may not be the best thing for signal integrity ever.

My hopes are currently on the AES-i to AES adapter, it seems to be *exactly* what should be needed.

S.

I’ve ordered both solutions proposed. Hopefully one of them will work.

You all are amazingly audio-geeky – when I talked about matching SP/DIF to AES at Guitar Center and Petosa, all I got were blank stares… and whoever posted the solution, did so anonymously!

Thanks, whoever you were. I don’t know that either one will work, but they both look like likely canidates.

Okay, first of all, in the Alesis AI-4 manual it states that a SPDIF signal can be fed to a AES jack by using a matching tranformer. After a quick web search for SP/DIF to AES matching transformers, I conclude that no commercially available product exists, and (as one could almost predict) reach for a microphone matching transformer, assuming that SPDIF must be about 48khz in bandwidth and will pass through a audio transformer just fine.

Then later I think to read about SP/DIF’s encoding system.

No.

SP/DIF is 3 !Megahertz! in bandwidth. To carry a 48khz signal! Fer crissake, I’ve worked on computer LANs that used less than 3 megahertz!

So, I guess my question for the audiance is, what kind of matching transformer does one use to match a low-impedence 3Mhz signal to a high impedence 3Mhz signal?

At this point, I’m tempted to get four AI-1s, just to have the whole problem over and done with. It *almost* works without a matching transformer – the audio is there, all pretty and clean and happy, and then suddenly ‘click-click-click’.

I’m wondering if I got a metal-can RCA to XLR adapter and used SP/DIF approved cables to go from it to the SPDIF jack if things would work better. A lot of the time I run SPDIF on regular RCA cables on the theory that it was 48khz, how far wrong could you go – but now that I’m discovering that the stuff is basically video, bandwidth wise, I’m rethinking my approach somewhat.

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I’m having a lot of trouble with one of my systems here. it’s a win2k machine running one IDE and one SATA drive, with a firewire interface board and a high performance video card in it.

One of the things I’m doing with it is editing video. It has a 30G and a 250G drive in it. Currently, the 30 gig clocks in at about 9000k/sec, and the 250G clocks in at about 1500k/sec. I know that larger hard drives tend to be slower, but by 10:1? Can someone please explain to me what I’m doing wrong? I installed the drivers that came with the motherboard…

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I can’t decide how I feel about this new drug that I’m on. On one hand, it certainly makes it easier to work on things continously, and to interrupt tasks and return to them. On the other hand, it also makes me constantly aware of all the things that I should be doing that I’m not. I never realized before how poorly adapted to the ‘adult’ world I am. (In fact, I suspect all of humanity is poorly adapted to it and that certain individuals in places of power like it that way – I guess we’re more tractible that way)

Feel free to critique.. (it’s about 3 minutes long, classic rock, the Art Theives as recorded live at Wayne’s World)

S.

So, I went rollerblading in a rink on Saturday – and I’m here to report, no soreness that lasted more than a day.

It was insanely fun, even though I couldn’t coax Kayti out onto the floor. Most of my rollerblading skill is gone – I can’t dance on them, and I can’t reverse at any meaningful speed, and I feel really uncomfortable when I’m going backwards. But, the basics are still there, and the rest feels like it might come back, given some practice.

Today I’m in a unreasonably good mood, partially because I reviewed last night’s practice recording and I think it sounds really good (http://www.sheer.us/stuff/MischiefCommittee/MischiefCOmmittee-130806.mp3 for those of you who want to follow along) and partially because I got some cleaning and a lot of minor work tasks done.

I also paid my bills (well, I haven’t actually put them in the mail yet) and entered them all into a spreadsheet – I am determined to stop overdrawing my bank account – they always pay all my checks, but they charge me $27 per! I calculate I’ve spent about $500 in fees this year. This has got to stop.

(They’re taking shameless advantage of unorganized people everywhere)

I’m coming up on my goal for this year for my stocks, and it’s only Augest.. (of course, the market could tank at any moment). It’s looking like I might actually have all my debts paid off by january or febuary.. not quite december as I’d wanted, mostly because of my desire for sushi 😉

I did some more work on www.sheer.us – I think I’m done messing with it for a while.

I’m sure you’ve all got one of these, but here’s a fun web snow generator:

http://www.sheer.us/functions/colors.php

or for the constantly refreshing model

http://www.sheer.us/functions/colors-r.php

Still updating my web site – today I added a random link generator. Now I just need to inject some more interesting links into the table that controls it..

I’m really wondering what things like google are going to do for indexing my web site, which now changes every time you access it.. (it’s muuuutating.. muhahaha, muhahaha), and if it will increase or decrease traffic.

So, aside from buying a bass guitar, I seem to be making other attempts to regress to my teen years. Specifically, tonight I’m going rollerblading in a rink. I’m sure that tomorrow, considerably black and blue, I will be posting about how much I regret this decision. Hopefully there won’t be any broken bones to deal with.

In other news, yesterday I tried the drug Adderol, and I can safely say that this is NOT the drug for me, at least not at the 20mg dosage. This isn’t any big suprise – after all I’ve never used any recreational stimulants and don’t want to. There’s another flavor of drug they’re going to try me on on tuesday, hopefully it won’t have the same bizzare peaking-while-crashing that this drug did. Side effects for me included time dialation, a bizarre metallic feeling which I would compare to one of the unpleasent side effects of LSD (it’s that feeling you get BEFORE things start getting really fun), emotional swings – the tiniest thing would make me feel totally crushed – and rapid thinking/talking/etc.

If the other drug doesn’t work I might try Adderol at 5 mg to see how that works out, but my inclination is to stay away from it.

So, I recently purchased a Access Virus T1, and I thought I’d post a review of it for those of you who are curious about what I think. (Probably no one, but nonetheless I feel this need to compulsively blog my opinions of consumer electronics).

First of all, let me comment on the sound. It’s beautiful. It’s lush. It’s fat. It’s probably even phat. It makes me feel like ten times the musician I actually am. I’m tempted to get out my AX-7 just so I can do windmills. It’s that good. Really. Honestly.

Unfortunately, other bits of the synth are.. how we say.. not so good.

First of all, it is the pickiest synth about MIDI incoming signals I’ve ever seen! Only about half of the thru ports on my other sound modules will drive it. As far as driving it from the output of a groovebox, forget about it. This synth wants very very clean midi, proper voltage levels, and no timing glitches at all, even 0.1%..

Second of all, you have to void the warantee in order to rack-mount it – there’s a rack kit, but installing it requires removing a waranty sticker. Smoooth…

Third of all, when passed random garbage on the MIDI bus, the synth !crashes!. Yep, just like Microsoft Windows.

However, despite all its flaws, I love the thing. The sound is so lush, so fat, so sweet.. and yet, with the twist of a knob, it can turn into all the agression of a DX-7 or all the sawtoothed insanity of a Prophet or Juno. It even has a bit of Moog stuck in there for good measure. It’s a wonderful sounding synth.

I haven’t yet started trying to integrate it’s CC implimentation into the mess that is my CC control loop, but I’ll let you all know how that goes once I’ve done it..