Gentlemen, T20 lives!http://redspade-audio.blogspot.com.a...-complete.html
What does T mean?
It could be tapped horn ...
It could be turbo charged ...
Or all of the above!
Yes, it is ugly (it will go under the house)
No, it's not as neat or pretty as just about any other Rythmik DIY build!
I made it dual opposed and it's really quite amazing how little the box moves. I can get the kind of output that would push the drivers as direct radiators, and you can barely feel the box move. Yet it's a giant horn that manages to be light enough for me to move it into the room from the workshop without help, without straining.
It is 2.25m tall x 600 wide x 400 deep.
Drivers mount here with a removable panel:
This is the mouth:
Driver is DS12 with 18mm xmax. This one was manufactured by TC Sounds and the basket is the same as that used on my previous subs - the 2003 version of the Acoustic Elegance AV12. As a direct radiator the Rythmik kills the AV12 in sound quality. The AV12 had a bit more thermal power handling and a bit more xmax, but the Rythmik is in another league.
Temporary position for testing:
It's quite a simple design with around 94 db sensitivity (simulated) and 120 db max SPL all the way down to 20 Hz. The tapped horn limits the bandwidth and I would say about 60 Hz would probably be the upper limit, whereas normally I'd run it up to say 80 Hz. Crossing it around 40 - 50 Hz means this becomes a very robust high SPL sub. The narrower bandwidth reduces the thermal load and power demands on the amp. The idea is to increase the sensitivity and output to match my horn system (Synergy horns). The amps in this design have just enough power to reach xmax limits and it is safe with a 20 Hz high pass added to the built-in 20 Hz first order filter. Basically it becomes indestructable! Previously it was possible to find the limits but that will no longer be the case.
So does the horn loading improve the sound? Does it degrade it?
I'm still asking myself this. It's hard to compare because it's a bit like getting in the driver's seat of a race car. I've had the kits since 2006 and I have not heard anything better than the Rythmik subs. (And no, I'm not a sheltered DIYer lacking exposure to high end systems).
What I notice with the tapped horn is that bass can tend to take on a tactile sensation. I have not had this with direct radiator subs. I'm not sure if it's related to running hot, or if it's some horn trait, or simply the ability to hit hard without compression due to the extreme output capability. Hard to say so far.
The bass with this thing is very potent. It's the closest thing to a live rock concert I've heard in a home. It's tactile and punchy. But at the same time it's taken up some bass trap real estate which isn't helping. I have a little get together coming up where we will run this along with a front loaded horn and various pro driver sealed boxes. That will be fun.