There are several single LAB12 Th's floating around on this forum, like the PAL12, for example. They are often erroneously referred to as "labhorns". The original design that the LAB12 is made for is as old as the hills - I have 8 of them built between 2002 and 04. And even that was a conventional-driver variant of one of Darnley' servo motor driven subs which was around for some time. The 12 Pi attempted to address deficiencies - but meanwhile driver technology moved on and you can get better results just starting over. My latest sub is similarly tuned, a bit larger and optimized for the 18TBW100.
The LAB12, however will still be around for a long time because it is a very good multi purpose driver when used within its $170 limitations.
The problem with a small form factor push pull LAB 12 based horn is that the two 12's are roughly equivalent to an 18 and would require a box appropriate for an 18. It might be easier to tune in with a pair of long throw Tangband 8's or 10's - there are several choices available to consider.
The LAB12, however will still be around for a long time because it is a very good multi purpose driver when used within its $170 limitations.
The problem with a small form factor push pull LAB 12 based horn is that the two 12's are roughly equivalent to an 18 and would require a box appropriate for an 18. It might be easier to tune in with a pair of long throw Tangband 8's or 10's - there are several choices available to consider.
Thanks, WG.
So I guess I should have titled the thread, simply "Danley TH212 Clone?"
- But I get the feeling guys around here don't like saying things like that directly.
Well, that's still where I'm at, I guess.
Or Art's dual 15" idea, but that might be too much of a compromise, size-wise. (I have no idea, but that seems likely.) I do want to get as flat as possible to 40 Hz or so.
So I guess I should have titled the thread, simply "Danley TH212 Clone?"
- But I get the feeling guys around here don't like saying things like that directly.
Well, that's still where I'm at, I guess.
Or Art's dual 15" idea, but that might be too much of a compromise, size-wise. (I have no idea, but that seems likely.) I do want to get as flat as possible to 40 Hz or so.
Originally Posted by weltersys
A fold pattern similar to the TH-212 could be expanded in one dimension to 42", reduced in the other to 31", depth increased to 17", and then use those Radian Neo 15" you have your heart set on .
2) Yes.
3) Since the path length could be the same as the 36" x 36" x 15" DSL TH-212, the LF extension would be the same.
4) The LF extension should be similar, the shape of the response determined by the drivers chosen.
5) Yes, since that is what you are looking for, and the FLH 45x45x22.5 LABhorn (using a driver specifically designed for that horn near the turn of the century, named after the ProSoundWeb's Live Audio Board) is far to big to fit in your pickup.
Art
A fold pattern similar to the TH-212 could be expanded in one dimension to 42", reduced in the other to 31", depth increased to 17", and then use those Radian Neo 15" you have your heart set on .
1) Yes, just yesterday. Here's the math: 36x36=1296/42=31(30.85714286)
2) Yes.
3) Since the path length could be the same as the 36" x 36" x 15" DSL TH-212, the LF extension would be the same.
4) The LF extension should be similar, the shape of the response determined by the drivers chosen.
5) Yes, since that is what you are looking for, and the FLH 45x45x22.5 LABhorn (using a driver specifically designed for that horn near the turn of the century, named after the ProSoundWeb's Live Audio Board) is far to big to fit in your pickup.
Art
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Again, nothing like the Labhorn or Danley. It appears sorta' similar in the side view, (except for its huge mouth) but look at the "production" photos. It's maybe 26" - 30" wide.
It's not even a TH.
And it's only reasonably flat when you use 4 of them.
Thanks, Art.
I'll probably give you a call this week. I think I have enough data to finally make a decision & try my first build.
Originally Posted by tmuikku
12pi push pull horn sub Pi Speakers - Push/Pull Basshorn Subs
You still don't seem to get the history, so I'll spell it out.
Tom Danley designed the spiral FLH 45" x 45" x22.5" LABhorn as a contribution to the Live Audio Board near the beginning of this century.
An employee at Eminence made the LAB12 driver to work in the design.
The LABhorn was pretty much the same in all design aspects (with the exception of the new LAB12 drivers) as Tom's Intersonics Servodrive Bass Tech 7 design from the early 1990s.
The LABhorn design was made after Tom he'd left Intersonics and had already started to design "Tapped Horns" (he came up with the new name for an old concept). Tom never directly shared any of the TH designs, as they worked quite a bit better than "too small" FLH designs in terms of LF output for a given size. That said, Tom shared plenty of TH details over the years with the DIY community.
Some time after Wayne P. and his sock puppet trolling were banned from the LAB, he decided to build a "better" version of the LABhorn that uses the same spiral horn configuration, but is wider, and used a push pull driver orientation. As he says "The shape of the horn is pretty basic. It is very much like some of the other common basshorn designs, but a little larger than most of them."
After burning up LAB12s, he also added a "heat exchanger" to reduce voice coil heat.
Like any rising response FLH, both the LABhorn and 12Pi low frequency response "fills in" when used in multiples.
TH response does not change as much in multiples.
Not sure what your definition of "reasonably flat" is, but like most Danley TH designs, the TH-212 has a rising response of over 6 dB per octave above it's Fb of around 38 Hz.
Art
12pi push pull horn sub Pi Speakers - Push/Pull Basshorn Subs
Cableaddict,
You still don't seem to get the history, so I'll spell it out.
Tom Danley designed the spiral FLH 45" x 45" x22.5" LABhorn as a contribution to the Live Audio Board near the beginning of this century.
An employee at Eminence made the LAB12 driver to work in the design.
The LABhorn was pretty much the same in all design aspects (with the exception of the new LAB12 drivers) as Tom's Intersonics Servodrive Bass Tech 7 design from the early 1990s.
The LABhorn design was made after Tom he'd left Intersonics and had already started to design "Tapped Horns" (he came up with the new name for an old concept). Tom never directly shared any of the TH designs, as they worked quite a bit better than "too small" FLH designs in terms of LF output for a given size. That said, Tom shared plenty of TH details over the years with the DIY community.
Some time after Wayne P. and his sock puppet trolling were banned from the LAB, he decided to build a "better" version of the LABhorn that uses the same spiral horn configuration, but is wider, and used a push pull driver orientation. As he says "The shape of the horn is pretty basic. It is very much like some of the other common basshorn designs, but a little larger than most of them."
After burning up LAB12s, he also added a "heat exchanger" to reduce voice coil heat.
Like any rising response FLH, both the LABhorn and 12Pi low frequency response "fills in" when used in multiples.
TH response does not change as much in multiples.
Not sure what your definition of "reasonably flat" is, but like most Danley TH designs, the TH-212 has a rising response of over 6 dB per octave above it's Fb of around 38 Hz.
Art
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That's basically one of the reasons I'm pretty much not interested in simple FLHs for high-power bass horns. Sticking a PA driver with its *** enclosed in a smaller wooden box is not going to be the best way to wick away heat from the motor structure!
I do have an idea for a split-path offset TL that should do wonders for wicking away heat (by convection), but I think the TH will still be the leader in that regard, with the driver's *** sitting in the mouth of the horn, an area of maximum velocity @ the resonance frequencies when cone motion is at a minimum (and the tendency for heat buildup is likely to be the most).
This is what the layout might look like, subject to further refinement. My plan is to get the panels defined in an Excel workbook, then use its optimization feature to work out the best dimensions and layout.
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Have you guys seen Wayne Parham’s idea for a driver heat sink?
https://audioroundtable.com/PiSpeakers/messages/17334.html
Do you think that could help much, or not very effective at all?
https://audioroundtable.com/PiSpeakers/messages/17334.html
Do you think that could help much, or not very effective at all?
Thanks for the background, Art, it's near impossible to know all that, starting form just this year.
Not "per octave," only for the first octave. Then it drops back down ~ 3 dB.
But I get your point.
Yes, 38Hz - 200Hz +/ - 3 dB fits my description of "reasonably flat. I have no hopes of flatter than that in such a small horn, and I have no need of flatter than that, either.
It is interesting, though, (now that you point it out) that the first main peak is indeed exactly one octave above the Fb. (assume it IS 38 Hz.)
Not "per octave," only for the first octave. Then it drops back down ~ 3 dB.
But I get your point.
Yes, 38Hz - 200Hz +/ - 3 dB fits my description of "reasonably flat. I have no hopes of flatter than that in such a small horn, and I have no need of flatter than that, either.
It is interesting, though, (now that you point it out) that the first main peak is indeed exactly one octave above the Fb. (assume it IS 38 Hz.)
Yep, I saw his idea and even toyed with doing something similar.
I built 4 labhorns off the original plans in 2001 for which Art gave you the history.
But I've never lost a driver through alot of heavy use.
And the more I thought about it, and what I believe to be true today....
is that the heat buildup issue, while undoubtedly real,
is IMHO waay overblown...to the point it's a bit of urban legend.
I do think several things can make the labhorns heat up faster than what they were designed for.
First, if the rear chambers aren't 100% airtight....goodbye!
Labhorns are not an easy build without proper tools.
Second, I'm guessing alot of folks who had them burn up had never heard bass so clean, so loud, without the usual complement of harmonic distortion....
so turn em up till they distort, which thermals 😉
And last, and not as well known, labhorns impedance moves towards, and stays near minimum above 90-95Hz.
My guess is more labhorns opened coils from trying to run too high in freq, than from grunting down low like they were built for.
You don't get much of that impedance rise using only one or two. You need 4. A single unit has several impedance minima, and driving it hard there will generate excess heat. People also had a habit of driving them with bridged PLX3402's, which isnt good for the amps either. I've never had to drive them over 85 volts, but I'm building something new for when 85 volts isn't enough. Or if I need both sets. I have run smaller FLH's with 15's trying to get the same levels, and driven them into pretty severe compression.
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