DIY sub for Klipschorn based HT (and music) - Tuba HT - build done (except for finish)!

[ClaudeJ1]

I think that Bill's description of his horn in a real room is a bit optimistic at 10 Hz. on his website. I asked him about the length of the Tuba HT on the High Efficiency Speaker forum and he told me his cutoff was based on a 25 Hz. quarter wave (11.25 feet long) and didn't feel going below this was necessary for HT or music. He is correct on music, but some would argue otherwise on HT

The original LAB horn, using two LAB 12's per box is almost twice the size of either box we speak of here. With a bit of EQ and room gain, it can get to 20 Hz. easily according to Tom Danley, and when it is part of my R and L channels, I will not need a sub if I don't want one. If you look at my Avatar, it's my Left Channel of a 2.0/5.0 system and barely gets to 40 Hz. Since I live in a condo, building any of these will either annoy or upset my neighbors depending on the outpu levels. With 106 db efficiency, it's hard to beat LAB horns if you can afford the cost and time to build them. Flat from 30-200Hz with the Brad Litz mods. It is an 11 foot horn also.The Tapped horn is 18 feet on the 1/4 wave side and side and almost 36 feet on the 1/2 wave side, so it's pretty easy to see which one goes lower for a given box size. The Tapped Horn wins every time. If you have no need to get that low, then the Tuba is the best choice if you can deal with the clumsy shape.

All the dimensions necessary for the "coffee table" build (mine will lay down) LAB 12/tapped horn that I posted are there or can be easily derived. There is only one angle, on the large piece, everything else is square (ok the little piece that forms the throat has a few small angles, but that's it). It is the easiest build of all, so that is why I want to do that first.

I don't really think you can go wrong either way. Bill's Tuba is a good solid design. The cubic feet of space is about the same for both, so it's a personal choice of placement, efficiency, bandwidth, etc.

For me, a TUBA HT is too clumsy of a shape for my space and too hard to build vs. the tapped horn, although it's easier than a LAB Horn.

It matters not to me how anyone uses LAB 12's. It's one of the best drivers for the $$ out there....a real winner, no matter how you use it (yes, even in an infinite baffle, but you would need more of them). For low group delay, transient response, low distortion, efficiency, whether tapped or not, the horn wins evey time, but you need accurate time delays. Choose wisely.

[ClaudeJ1]

As I said earlier since I have the 2 x 12" Eminence LAB speakers I might as well build some TUBA's or tapped horns with them, that way if I decide to dive into the world of IB I can sell a working set of subs!

If you build either of those, you won't need to sell them.

Claude, have you ever heard an IB or either horn sub in question?

I helped a friend build twin Danley derived SPUDS, which have twin Tang Band 8" sub drivers, easily the equivalent or better than a single LAB 12 in terms of motor strength and cone area. Since we cross at 40 Hz. you cant hear them but it certainly feels like an earthquake under the house. He also has a third one not hooked up yet. So yes I have heard them. An IB is too expensive in terms of number of 18" woofers, amplifier power, inefficiency, etc. I have never heard one, but William Cowan, a well respected Australian Engineer used to have a bunch of 18" woofers in an IB configuration and now prefers his multiple tapped horns over that. I can't afford to prove him wrong, but as long as you are happy and you feel you may have done so with your IB setup, then all is well.

[Vicoaster]

I tried to upload plans last night......VERY simple build. For some reason, they woudnlt upload. I will try again.If not, I will try a link to the DIY since there are thousands of posts on tapped horn. It was hard to find this one.

So is this the same one? Looks like it to me. http://www.diyaudio.com/forums/subwoofers/143714-lab12-tapped-horn.html

Interesting comment in post #8... only good to 70-80Hz? Wasn't the inductor for 150 Hz rolloff? Besides if this is connected to the LFE channel most are low passed to 120 Hz. Either that or I could use the cossoever in the AVR or an electronic crossover.

See this thread for some great pictures of the Danley: http://srforums.prosoundweb.com/index.php/m/500239/0/#msg_500239

[CECAA850]

I have never heard one, but William Cowan, a well respected Australian Engineer used to have a bunch of 18" woofers in an IB configuration and now prefers his multiple tapped horns over that.

I see where he's designed some. but I've never read that he prefers it to his IB. I couldn't find where his tapped horns reached anywhere near the 112 dB @10 Hz that his IB does. I did however only look at his website, there may be some postings that I haven't seen however.

[psg]

Started off the evening taking better pictures before sealing it up.

[psg]

All I got done in nearly 3 hours is a dry fit of the side panel, marking inner edges with a pencil, removing the panel, drilling hole and glueingin the panel again secued with a bunch of screws. Forgot to take a picture, but it doesn't look like much anymore except a very large box. [:|]

Next week I will sneak in on Tuesday to remove the screws and fill the holes with walnut-colored latex wood filler. Wednesday I will run a router on all edges and sand a bit, and cut my last braces and the access panel insets. I will likely bring everything home to finish glueing those last pieces in the comfort of my home, and finally test the thing out and stain it a bit later on.

Still haven't ordered the USB sound card for REW, or the 1124p for EQ, but I guess I can play with it without that first.

[Vicoaster]

Looking good Peter, a lot more complex now seeing it from the side view!

You mentioned taking out the screws, would there be a problem just leaving them in? I have built many speakers, usually I just leave them in place after the glue sets...

[psg]

Yeah, that's a complicated build compared to a plain box.

I would leave the scrwews in if I didn't plan on running the router on the edges. They are pretty close and i am affraid of hitting them. It appears to be pretty common practice to remove them, but i would feel better with them in there.

BTW, I have edited the first post of the thread to highlight relevant pages. The thread is already too long to find a past post quickly!

[CECAA850]

Nice Peter! You're almost there.

[psg]

Almost! Should get sound out of it by next weekend, althought it won't be stained yet.

There are two Crown XTi 1000 up for sale in the garage sale section of the forum. That would combine power and DSP into a single affordable package. But I am worried about the lackluster performance of that amp at 20 Hz / 4 ohms under steady state conditions

i.e. http://www.crownaudio.com/forums/index.php?showtopic=2438

Perhaps that doesn't apply too much for dynamic content, but 100W is pretty anemic right?

Alternatives are miniDSP and Behringer EPQ1200 combo that uses RCA
connectors, or maybe a Behringer DSP1124p and EP2000 comb, switching
from RCA to balanced between the receiver sub out and the EQ
processor. The Crown would likely cost $330 to $375, with a pair of
RCA-to-XLR cables from monoprice, once it gets to me across the border
(with the range explained by taxes or not at the border). The miniDSP +
EPQ1200 would run me about $530, so the difference is not all that
great. Crown is a better name than Behringer, but the XTi issue makes
that particular model not as good as the more expensive ones. Of course I can the Tuba HT soon without buying an amp. I have a Monster MPA2250 on loan (but it has no gain control and that might be an issue, but has real power meters which will be useful to gauge what power I really need) and my old unused harmon-kardon avr-325 receiver.

[ClaudeJ1]

Perhaps that doesn't apply too much for dynamic content, but 100W is pretty anemic right?

Not when a 10 Volt signal at 20 Hz will flex your windows by 1/16th of an inch (about 12 W) at 120 DB of sound pressure with a TUBA HT. Isn't this the reason you built a HORN sub to begin with? The higher the amplifier power the higher the distortion, so horn loading keeps things low distortion and avoids non linear behavior which starts to happen at 20 Watts RMS for many voice coils.

[psg]

Salut Claude,

You make a valid point. But I guess my point is that I probably shouldn't bother buying a 500W into 4-ohms amplifier to match my driver's specs if that amplifier can only do100W at subwoofer frequencies. My unused hk avr-325 was tested to 135W into 4 ohms (likely not at 20 Hz), so maybe I should just use that.

Do we know how much power the Tuba HT can take at 25 Hz before reaching xmax? It is the driver's rating, e.g. 500W? or different because of the horn-loading?

You are really getting 120 dB at 20 Hz with 10 V (20 W into 5 ohms) with the Tuba HT? Wow... I am in for something special. I have no windows in my HT/audio room. [Y]

[psg]

The sub left the shop 10 days ago, and stayed in my van for 3 days because it rained all the time (rain in this part of the country in December!?)

Here it is in the van. My wife wasn't strong enough to lift it so I had to ask a friend. Even without the driver, access hole flanges and panel, and the last three braces, it was very heavy. It took all of me to get it to the basement intact!

[psg]

The driver is in now.

I glued in my access hole flanges last night, and the three last braces
minutes ago. Tomorrow I'll be ready to cut a hole in the access panel
for my banana plug plate, solder speaker wire into the plate, install
the plate and then the access cover... and it will be functional and
ready for try-outs! Final finish will be done later this winter.

A bunch of pictures tomorrow... It's standing on it's front now so that the braces can dry in there with gravity holding them in place. Doesn't make for nice pics.

[Vicoaster]

The driver is in now.

I glued in my access hole flanges last night, and the three last braces minutes ago. Tomorrow I'll be ready to cut a hole in the access panel for my banana plug plate, solder speaker wire into the plate, install the plate and then the access cover... and it will be functional and ready for try-outs! Final finish will be done later this winter.

A bunch of pictures tomorrow... It's standing on it's front now so that the braces can dry in there with gravity holding them in place. Doesn't make for nice pics.

Wow, it looks bigger then I thought, how wide is it again?

Looking forward to the pictures, and the report of how it sounds, I wish I could get started on mine, I doubt it will be until next year now! [:$]

[psg]

It's 36x36xWidth. The width is variable with the same design. Mine is 30 ich wide, which fits through all my doors. It's lying on its side in the van. It couldn't have been much larger and still fit in there!

[rennoc442]

PSG, you are building the system that I want to do! How is the 6.1 setup? Is there a lot of movies in that format?

[ClaudeJ1]

Salut Claude,

You make a valid point. But I guess my point is that I probably shouldn't bother buying a 500W into 4-ohms amplifier to match my driver's specs if that amplifier can only do100W at subwoofer frequencies. My unused hk avr-325 was tested to 135W into 4 ohms (likely not at 20 Hz), so maybe I should just use that.

Do we know how much power the Tuba HT can take at 25 Hz before reaching xmax? It is the driver's rating, e.g. 500W? or different because of the horn-loading?

You are really getting 120 dB at 20 Hz with 10 V (20 W into 5 ohms) with the Tuba HT? Wow... I am in for something special. I have no windows in my HT/audio room.

Well then, you should be able to flex your drywall by 1/16th of an inch with 100 Watts. My comment about power handling and non-linear bahavior in woofers (power compression) has to do with the "10% rule." Voice coils thermal (even the vented ones) behavior increase the resistance of the copper as more power is added. This power compression can be measured and starts to be detectable at abou t 10% of a driver's max. power rating. Obviously, as you add more power there is more heat, but not as much sound, getting progressively worse as power is increased until a driver fails.

I honestly don't think you will need more than about 20 W of continuous power to shake your house, but, if you have 500 Watts, you won't have to worry about clipping, eh? Just be careful with the beast you have built.

This is why I like to see amplifiers rated in DB Watts instead of watts. a One Watt amp. is 1 dbWatt, a 10Watt am/ is 10 dbW, a 100 Watt am/ is 20 dbW, and a 1,000 Watt amp is 30 dbW, so you can see that power is gobbled up very quicly as volume goes up, much faster than the sound output and progrssive increase in distortion. This is why horn bass rules them all. It's much cheaper and lower distortion with high def. and sound quality to add lumber rather than more drivers and power amps, IMHO.

[ClaudeJ1]

Peter, let us know how it feels. It will affect your testicles more than your ears when you finally hook it up. LOL.

Hey, why do you think it's called the "bottom end?"

[psg]

PSG, you are building the system that I want to do!

Heritage? Tuba HT? That combo?

How is the 6.1 setup? Is there a lot of movies in that
format?

7.1 isn't practical for me as far as speaker placement, because of a doorway where one speaker would go. When I get a projector, one possible spot for it would be that center rear speaker, so 7.1 would be nice if a Heresy II could be made to work on the other side of the door, in the corner. Otherwise the projector may go on the top shelf of the AV rack with some horizontal offset. Another problem there is that the AV rack doesn't go up as far as the ceiling such that the projector wouldn't be as far up as I'd like.