Resampling in Mac OS :(

Recently I’ve been experimenting with higher definition music downloads. For example, the Studio Masters recordings from Linn Records, or the material from B&W Society Of Sound. Everything went nicely until I got my new Mac.

First of all, the only lossless format supported by iTunes is Apple Lossless. It won’t play FLAC (the open source Free Lossless Audio Codec) properly, even with the xiph.org extensions, Fluke, or whatever. A bummer, as I already had a fair amount of music in FLAC format. Sure, VLC will play it, but VLC can’t understand iTunes playlists.

Second, Linn don’t support Apple Lossless. They supply their music in FLAC and WMA formats only. I guess they’d rather you bought their own stupid, overpriced DS network media players, even if you have a Mac already.

Third, Mac OS resamples! Windows was smart enough (or dumb enough?) to set your audio hardware to the actual sample rate and bit depth of the track that was currently playing. Or at least the setup I used, Winamp Classic with the ASIO driver, would do that, guaranteeing bit-accurate output under all conditions.

The Mac doesn’t. You set the sample rate and bit depth once and for all in the audio control panel, and all the sound gets resampled to that. You can play 96kHz material till you’re blue in the face, using any player application you like, but if the system sample rate is set to 44.1, it’ll get downsampled. Watch a DVD, and the sound is getting resampled from 48 to 44.1.

I don’t know about you, but I wouldn’t trust any resampling algorithm I hadn’t written or at least tested myself. They’re notoriously hard to get right. And a “right” one consumes so much CPU power that there’s a real incentive to downgrade the performance deliberately.

Here’s the official line from the Coreaudio mailing list, found here

This was a comment posed to the list (which was replayed verbatim from Benchmark’s Elias Gwinn)
> […] If the user changes CoreAudio’s sample-rate in AudioMIDI Setup to something different than what iTunes is locked to, CoreAudio will convert the sample rate of the audio that it is receiving from iTunes. In this case, the audio may be undergoing two levels of sample-rate conversion (once by iTunes and once by CoreAudio). (The SRC in iTunes is of very high quality (virtually inaudible), but the SRC in CoreAudio is horrible and will cause significant distortion.) If the user wants to change the sample rate of CoreAudio, iTunes should be restarted so that it can lock to the correct sample rate.

This is the response from an Apple employee:
iTunes uses the AudioConverter API internally but we set the quality to “max” and AUHAL probably uses the default (I don’t know). One SRC at max quality followed by one at the default quality is not so great when analyzing sine tone playback.

So the bottom line seems to be, that if you have material recorded at a higher sample rate than 44.1, then you need to turn your system’s sample rate up to appreciate it. And if you do that, then all of your other stuff will get upsampled, though at least it uses Coreaudio’s best quality algorithm. Or does it? Leopard introduced a new “Mastering grade” algorithm, and it’s not obvious whether that one is used.

One step forward, two back. Come on Apple, twiddle those nose rings and come up with a sexy solution.

To EQ or not to EQ, that is the Q

If you’re a follower of hi-fi trends, you might have noticed that tone controls don’t seem to be cool any more. High-end amplifiers have become very minimal, with only a volume control and power switch.

Well, there’s high end and high end. Richard Burwen’s system would certainly qualify as high-end by almost any definition, if only because of its 20,000 watts of amplification, 169 speakers, and 34 channels of active crossover and EQ, which Burwen claims to have spent a year adjusting by ear for a flat overall frequency response. In other words, the very opposite of a minimal system.

Moving on to my own hi-fi system, which has 60 watts of amplification, 2 speakers, and no tone controls or EQ whatsoever, and has been plagued by annoying room modes. I’ve tried several different speakers, but the bass on all of them just sounded terrible in there.

Recently, I realised that the fundamental problem is that my living room has the two large opposing walls made of solid brick. These two reflective surfaces allow a standing wave to develop between them, and the result is a highly resonant bass boost of about 9dB at 60Hz. I fed the measurements of the room into an online room mode calculator, and it agrees that I should get terrible bass.

So, what to do about it? The minimal solution would be to damp the resonance by installing bass traps. This would be a major carpentry project, though, and good bass traps have to be physically large, so I would lose space in the room. And, I hate working with rockwool, it makes me itch all over.

So, like Richard Burwen, I decided to install an EQ, and “tune by ear for flat frequency response”. My first attempt was with an Alesis PEQ-450, which is a 10-band digital parametric EQ. It only took about 5 minutes to find the offending frequency and notch it out, and I was amazed by the improvement. I found myself getting out those old hip-hop and drum’n’bass CDs that had just sounded offensive on the system before.

However, I wasn’t too happy with the sound quality of the PEQ-450. Maybe I was imagining it, but I felt that it grunged up the treble somewhat. It was also too big and I had nowhere to install it. I ended up buying two (they’re mono) Presonus EQ3Bs on Ebay, and again, tuned them by ear for best bass. I could have gone digital with a Behringer DEQ2496, but in the end, I decided that the simpler solution would be better.

So now, I find myself in the situation of committing audio sacrilege (tone controls are bad! So EQ must be worse!) in order to get a major improvement in the performance of my audio system. Mmm, sacred cowburger.

EQ

The EQ3Bs in place

The system

The system. The graffiti paintings are by my brother, and help to break up standing waves too. 🙂

Goodbye decks…

Lack of DJ skillz and impending middle age forces sale! ;-(

There’s a story behind me and decks, which I can tell now that the 10 year non-disclosure agreement has expired. In my final year at university, I took the “Innovation For Engineers” class, which taught how to be an entrepreneur. Myself and another student, Andy Williams, decided that we would have a go at entrepreneurship for real. Andy knew I was a mad inventor, and he lent me money to develop one of my inventions, in exchange for half of the profits. (lesson 1 in entrepreneurship: never give anyone half of the profits)

The invention I chose was an improved crossfader for DJ mixers. I’d just fixed a DJ mixer for a friend, his crossfader had worn out, and I thought I could invent one that would last for ever. I soon had a prototype together, and we took it to music industry trade shows in Manchester and London to attract interest. The first interest we got was “Company G” who offered us £10k to bury the thing, a la everlasting lightbulb. (In hindsight we should have taken that.)

After a lot of board treading, we got the attention of “Company N” who agreed to buy the invention off us and fund the patent. Enter endless messing around with contract and patent lawyers. All went well until a substantive patent search found that I had reinvented a mechanism first patented by RCA in the 1970s. Game over! We walked away with £5k each, after a year’s work, for a net hourly rate comparable to flipping burgers. But it was certainly an interesting experience.

Company N launched the new fader anyway, in their Pro SM-3 mixer. Sales were so-so and the model was discontinued after a while, the company choosing to get out of analog mixers altogether and go to a digital solution.

Fast forward to 2 years ago, when I finally decided to buy some decks of my own. I bought a second-hand pair of Technics 1200s, only to discover to my surprise that I’m a crap DJ! I can match beats, but I can’t be bothered shopping for records, and have no idea what sort of records I’d want to buy anyway. And if I ever do buy any, I can’t remember the right places to mix them into each other.

The decks had their finest hour at my 30th birthday party, where I persuaded a friend of a friend to come and spin drum’n’bass on them. My flat was well and truly rinsin’! Unfortunately the rest of us got completely drunk, kicked him off the decks and started to play Blondie. He didn’t drink, and left in the huff. The party was still going at dawn the next day. Sorry, Chris.

Now I think it’s time to move on. Feel free to bid on my decks on Ebay! 🙂

decks for sale!

Transformerectomy!

No, it’s not some sort of futuristic android sex change.

I’ve lived happily with the Crown SXA for about a year now, and by and large, it’s been a pleasure. It sounds great, has more than enough power for me, and now winter is coming, I can warm my feet on it!

My main worry, though, was always the power transformers. Not only are they something like 50 years old, but they were never designed to handle 50Hz power, which is what we have in the UK. So, even with RG Keen’s Vintage Voltage adaptor installed inside the chassis, they hummed really loudly, got really hot, and gave off worrying smells.

My first port of call was Sowter Transformers, a custom winding company in Ipswich. I sent them the dimensions of the original trannies, and got the reply: “We don’t do metric sized transformers”. They were made in Indiana in 1960. How can they possibly be metric? But none of Sowter’s standard core sizes were even close.

So I thought, maybe “metric” just means “Not British”. A quick peek in the Hammond catalogue (sorry, catalog!) and sure enough, there were several transformers of the right size. I settled on the 290KX, which is Hammond’s replacement for the Marshall JCM900 guitar amp, and Bluebell Audio in Dundee supplied me with a pair.

After purchasing some end bells from TAD and some M4 threaded rod from “boltmeup”‘s Ebay store, it was time to pull the poor Crown apart!

dismantled!

This took most of the day. The new trannies had lugs sticking out of their bobbins, and needed some trimming to get them through the chassis holes. “It’s just like trimming a toenail”, as Philip from Bluebell told me, but much more expensive if you get it wrong!

New vs. old

After much fiddling, rewiring the rectifier to a bridge, wiring one of the transformers up backwards (thank goodness for the old light bulb limiter trick!) and pulling out the redundant Vintage Voltage unit, she was good to go!

done!

The bad news is, the new trannies still hum a bit. They’re quieter than the old ones, but not silent. They also still run fairly hot. The good news is, they don’t smell!

I finally painted the OPTs black to match

Fort William or bust. Or both.

The United Kingdom has exactly one track suitable for World Cup downhill racing, and it’s situated at the Nevis Range ski resort near Fort William in the Scottish Highlands. According to the Nevis Range blurb, the track is “built to test world-class riders and their bikes to the limit”, or something like that. The gondola juddered out of the bottom station and began its crawl up the mountain, with me inside and my Hustler dangling on the back. I wondered, not without a little fear, what kind of a “testing” would be dished out to a so-so rider on a cross-country bike with Domains bolted to the front.

I’ve known about the Fort William track ever since it was built, and like many other Scottish mountain bikers (I should imagine) I’ve oscillated between wanting to ride it, and being scared to go anywhere near it. I nearly did it last year, but after watching this YouTube footage I was scared off by the gratuitous amounts of big air. But this year, with a week off work and nothing else to do, I oscillated my way onto the 9.07 train from Glasgow Queen Street to Mallaig, via Fort William.

Some magazine poll somewhere voted this the most scenic railway journey in the world, and once you get over the shock of passing through the nastiest parts of Glasgow, it probably is. The journey across Rannoch Moor fills you with a massive sense of “Whose crazy idea was it to build a railway here?” And if you carry on from Fort Bill to Mallaig, you’re on the route of Harry Potter’s Hogwarts Express. (The big bridgey thing is the Glenfinnan Viaduct.) In fact, if you catch the Jacobite Steam Train, it probably is the Hogwarts Express.

But I digress. I analyze things too much, and if I thought about the consequences of everything I was going to do, I would never even get out of bed. I found that the secret is just to take steps one at a time, without thinking about the ultimate goal. Get out of bed, get dressed, get packed, get on the train, get off at Fort Bill. Follow the (very nice) cycle path along the A82 towards Inverness. When you reach Torlundy, leave the road and follow the signs through Leanachan Forest. See the downhill track slashing clean down the side of Aonach Mor, a white scar of switchbacking loose dirt and rock gardens, recently regraded from “Black” to “Bike Park Orange”. Oh no! But that’s the beauty of the baby steps method, by the time I actually think about the stupidity of what I’m going to do, as old Will said, “I am in blood stepped in so far…”

The next step was to get a gondola pass, and if you’re not a regular user, to do this you have to sign a “participation statement”. It’s basically a waiver that says, “I understand that the downhill tracks are hardcore badass and if I get hurt or killed riding them, it’s not Nevis Range’s problem.” I actually like signing these things. I hate the culture of litigation. I ride mountain bikes in full knowledge of all the awful things that could go wrong, and I wouldn’t dream of blaming anyone else for an accident.

Well, except maybe Mr. Newton and his law of universal gravitation, which says that objects attract each other with a force proportional to their masses and the inverse square of the distance between them. Standing on the “Pinkbike.com” start platform, feeling like a total newbie in the ridiculous plastic body armour I hired from the bike shop, that gravitation seemed awfully strong. But there was now only one baby step remaining, to release the brakes and put in a couple of good cranks, and that was what I did.

The little board at the gondola station said “DH track conditions: Fast and dry”, and indeed it was. The speed began to build amongst clouds of white dust. Right hand berm, hip jump, doof! came up short, into a left hander, some rocks, boardwalk, more rocks, left hander onto more boardwalk, Yeeha I feel like Steve Peat! Then the first of the big rock gardens, Hey what does all this red spray paint mean, Smash, Arrgh, fuck! I fly over the bars, bounce off an enormous red crash mat (no doubt placed by Nevis Range in fear of litigation), plough along on my side for a bit, and I’m lying face down in the dirt, everything hurts in spite of the armour, and I hear a hissing noise which is of course, to cap it all, a puncture.

Could this be why real downhillers walk the course before riding it for the first time? I had plenty of time to reflect on this as I mended the puncture, a process whose details I won’t bore you with. Was this real mountain biking at last? If you go to a major trail centre like Glentress, the trails are smooth and manicured. Even the rock gardens are just token features, with smooth rocks deliberately placed to give an exciting feeling of riding over rocks without actually being dangerous. But here it was as if the rocks were just left the way they were on the hill, or worse, arranged in diabolical jagged heaps to “test world-class riders to their limit”. And yet in the middle of all this hardness and machismo, someone thoughtfully placed a big foam crash-pad.

After a few more of these comedy crashes, I somehow made it into the section that the DH riders call the “motorway” and was able to lay off my burning brakes at last. As the name suggests, this is fast and smooth, but unlike the M74 it’s packed with big TV-friendly jumps, each one with fire road access and viewing platform for the World Cup camera crews. This is the section I was afraid of, after watching all the big air madness on YouTube. But now I was actually riding it, the jumps didn’t seem that big! They were only about two-thirds of the size they had grown to in my mind. Ok, I admit I was so tired from the top section that I couldn’t go fast enough to clear them, but nothing bad happened when I came up short, and in my book, any jump that you can case without getting hurt is an easy jump. The World Cup riders must be pedalling like stink all the way down here to get the amount of air that they do.

The last bit of the motorway drops straight into the Nevis Range car park. It’s the main part that punters at the World Cup will see, so they made it pretty big. You plunge down a steep chute called “The Wall”, a flat left-hander, then over a huge mound of dirt which is also a berm for the 4x track (with a little kicker ramp that you can use to launch yourself clean over the hill, if you’re faster than me and didn’t scrub speed before going down the Wall) and finally two large drops to flat. Bang, doof, the dent in the Hustler’s seat tube from the rocker link slamming into it gets bigger. Thud, screech of brakes, holy shit, it’s over and I kind of survived it. “Are you coming back up for another go”, asks a guy on a Santa Cruz Bullit who saw me crash on the way down. He came all the way up from Portsmouth to do this track, which is dedication. Yeah, I’m coming.

Waiting for the train in Ft. Bill station, I got talking to an elderly couple whose son, they told me, was into mountain biking. “He broke his collarbone down at Glentress, you know.” Oh, I said, did it heal lopsided? Yes, he now has one shoulder wider than the other. And yet he never signed a participation statement. They commented on my leg, which looked like it had been cheese-gratered in spite of the knee and shin guards.

“You mean you got hurt like that, and you went back to ride the downhill course again?”

I said, “Yeah, it’s like falling off a horse, you have to get straight back on again, or you’ll lose your confidence.” Or something like that.

Happy birthday bro!

This is a message to my brother, whom I’ve literally not seen or heard from in years, and whose birthday it happens to be today. So happy birthday from me, mum and dad! Hope you, Rowanna and the kids are doing well. And please get in touch, since none of us has a clue where in the world you are or what you’re doing…steve 

Carron Valley in black double diamond shocker!

I was doing some reading on the failure of the Carron Valley trails project, when I came across this… Funniest thing I’ve seen all week! Black diamond grade? Doubles with aggressive faces? Massive air?!

Are we talking about the same Carron Valley here?

I ask you, ladies and gentlemen of the jury, is this really “massive air”?

The headless biker of Carron Valley

And if that was massive air, then what’s this?!

Or were CVDG simply stitched up by the 7Stanes crew?