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Old 2nd April 2005, 11:06 AM   #1
Twelve Cycle is offline Twelve Cycle  United States
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Location: Bakersfield, California
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Cool Intro: I think I should sign up for this!

Greetings, all!


I have been wandering around the place, and it is a BIG place, and I can see it's going to take a while longer!

Hmmm... it's a bit intimidating too... what could I possibly hope to bring in to entertain such an illustrious crowd? well, here goes...

Generally I enjoy listening to music in stereo. Multichannel is nice, but I prefer it for movies. I guess I'm just old school.

Dynamics are very important to me, both in recording and reproduction. I feel a speaker should reproduce every characteristic of the original signal as accurately as possible, BUT, I am content with listening to whatever is available wherever I am, and am not judgemental in that respect. I can even enjoy music at work on employees' boomboxes - well, most of the time!

As for DIY, I have been interested in audio, especially speaker-building, for years and am always learning more with every project. The chronology gets blurry here, but my first homebuilt speakers were a pair of black lacquer Daline TLs that used a Focal 6" woofer/1" tweeter set from Zalytron. I don't think I will ever do lacquer again! While not a be-all-end-all it was enough to convince me that one can build much better speakers than one can buy, and I have never looked back since. These are currently in use at a friend's house (and they are looking pretty sad now!).

I found a few friends (Dave Draper, John Jackson, Charles Sprinkle) that had the audio bug, and things started to roll. Dave was into car audio and has built many systems. At one time I was running my home system on car amps until I could get more channels. John ate, drank, breathed and slept audio and music. He was the one who got us going to CES. Charles got hooked by hanging out with us, and is now a transducer engineer at Harman International (and John is now an intern there). Go figure!!!

There were several attempts/experiments with tube-style subwoofers, but at the time my friends and me were craving something that could play the lowest pipe organ pedals without flapping. There wasn't much TL info back then, so using the Dalines as inspiration, along with the SWAG algorithm (Scientific Wild-*** Guess) we came up with some ideas and I designed a TL sub around the old 18" Radio Shack woofer, which was the only driver (that we knew about) that had the specs we needed. When I showed them the plan, they were surprised at how big they were - "well, if you want 16 Hz..." We built one and it worked very well, as long as you crossed it below 60 (nasty hump above that). Serendipitously I missed my vent target of 16 Hz and ended up nearer 12, hence the moniker.

We started going to CES, and seeing all the different topologies/methodologies/technologies in one place was truly incredible and extremely inspiring.

The next speaker on the drawing board was a Dynaudio d'Appolito. This was put on the back burner after we saw the Bohlender Graebener planar magnetic drivers in action at Wisdom Audio's first showing, and retired after I obtained a pair of the RD75s (ouch$$$) and tried them in various baffles. Their first system incarnation was a dipole setup with separate woofer cabinets, and it became apparent that it would take a really good woofer to keep up with them. To make a long story short, John found some Dynaudio 24W75s on sale, and these went into sealed boxes, four woofers per side (we really needed eight per side, but that was all they had, I was tapped out, and I didn't have enough amp channels anyway).

After a couple years I decided to build monopole sealed boxes for the RD75s. Dave had constructed a set of monopoles using the RD50s (with a single 12" woofer below) and was of the opinion that monopoles sounded better than dipoles (I'm easy to please. I like the airy sound of dipoles, even if some feel it to be artificial). My room really isn't big enough for dipoles anyway, and though I missed the airiness and big soundstage, it was made up in imaging and accuracy, and I like them as monopoles.

The RD75s are crossed at 300 Hz to the woofers, and these are crossed at 45 Hz to the subs, via a 3 channel Marchand electronic crossover (24dB/oct/).

(TIP OF THE DAY: Don't set up your newly built speakers for a test listen BEFORE the cabinets are finished!)

I built another 18" TL sub, and traps and diffusion (my room is horribly dimensioned - 16x17x8 feet!), and this is the system as it is today, in the middle of the journey... after all, is one ever finished? It is up for a rebuild; in the future at some point I would like to have woofers all the way up so as to get a truer line, and the subs could use an update. I am a big fan of line sources and someday hope to build a full length planar magnetic driver.

This is the really fun part - being able to make my own drivers. I am experimenting with and building planar magnetic drivers and have had some success, with 1k-12k response so far from a 15" long driver, but nothing that would be considered usable in a system yet. My poor Threshold amp! It's a real trooper - when it's not running the RD75s it pulls duty as my mad scientist lab amp - I throw every imaginable experimental ribbon impedance across it and it keeps on ticking, though I have blown a fuse or three... My current project is a 4 foot line for which I just ordered magnets today.

I don't know how to HTML pictures in here with nice captions, so I will have to put more pictures in later (?) I have attached a pic of one of the subs.

Well, I think I've rattled on enough for now. Time to see if all this goes thru (I'm no typer).

Twelve Cycle
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Overkill is a good place to begin.
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Old 3rd April 2005, 03:33 AM   #2
audiousername is offline audiousername  Australia
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Location: Melbourne, Victoria
Default Re: Intro: I think I should sign up for this!


Originally posted by Twelve Cycle
Generally I enjoy listening to music in stereo. Multichannel is nice, but I prefer it for movies. I guess I'm just old school.
Don't worry, we've got thousands of old school two channel fans here. More than a few vinyl and valve fans, too.

Very interesting post. It looks like you'll fit in just fine
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Old 3rd April 2005, 04:05 AM   #3
SY is offline SY  United States
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Join Date: Oct 2002
Location: Chicagoland
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12C, welcome! It's delightful to see someone working on things that really make a difference. There's a lot of creativity in the design and construction of drivers; I'm really interested to see what you come up with.
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
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