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

[psg]

I think the stripper pole needs to be more towards the center of the room.

It was actually dead center when I started the project! Right in the sweet spot too. I had to add two poles to carry the load before I could cut it off with a zip cut. One is the one you see on the plan (and give me a spot to put a Tuba that I can't do much else with) and the other is hidden in the adjacent wall, next to the Heresy II wall inset.

[CECAA850]

A couple of questions... What sort of gear is needed for the EQ? I hear some version of Audyssey may be sufficient?

If you already have a receiver with Audyssey, it may suffice. Try it before you buy something else. If you don't, look into getting a BFD. It takes a little time to get the hang of it, but it's worth it. you're basically getting a 12 band PEQ for around a hundred dollars.

[psg]

http://bfdguide.ws/

I'm glad I asked! I learned something new today! Thanks!

My receiver is not Audyssey based, it's a HK-254. I use it without it's EQ engaged! I felt itkilled the dynamics somehow. I will eventually get into proper measuring the room response.

[psg]

You know, I'm told between these subs. It seems like room placement might be the deciding factor.

Ideally, I'd use the two SPUDs as a second row stage, but they could also be along the left wall. The THT would pretty much have to be along the left wall, either half way below the surround Heresy on the other side of the support pole, or behind that toward the rear corner. Which is best?

[tragusa3]

I'm using MultEQ that's on my processor. It does make quite an improvement on my subs, but the BFD is still necessary.

Although sub frequencies are said to be omni directional, with these high output subs, thier location is easily distinguished with any nearfield placement. It's hard to hide 120db flapping your pants around! I could always tell if it was coming from my left or right when I tried sidewall placement. You may want to consider this. I found mine had to be 15' from me otherwise I knew right where it was.

At the full price of the Danley, and having heard what the Tubas can do, I would build a Tuba. Of course, the Danley kit was.....well, you know.

[jason str]

I'm using MultEQ that's on my processor. It does make quite an improvement on my subs, but the BFD is still necessary.

Although sub frequencies are said to be omni directional, with these high output subs, thier location is easily distinguished with any nearfield placement. It's hard to hide 120db flapping your pants around! I could always tell if it was coming from my left or right when I tried sidewall placement. You may want to consider this. I found mine had to be 15' from me otherwise I knew right where it was.

At the full price of the Danley, and having heard what the Tubas can do, I would build a Tuba. Of course, the Danley kit was.....well, you know.

Sounds about right, build 2 smaller Tuba HT's, if i had the room this would already be running here.

The minimum size for the 15" driver is 18" wide ( 18 x 36 x 36 ) or the 12" driver version ( 15 x 36 x 36 ).

Constructing 2 at a time would not be the worst thing, once the first few steps are completed it comes natural if you enjoy woodworking.

Most of your time will be waiting for the poly to dry, making 2 will be more constructive with your time if you keep busy with the project.

[nyt]

MultEQ XT is great, I haven't played with standard multeq yet, but it was able to eq everything incredibly flat with XT.

I'm using MultEQ that's on my processor. It does make quite an improvement on my subs, but the BFD is still necessary.

Although sub frequencies are said to be omni directional, with these high output subs, thier location is easily distinguished with any nearfield placement. It's hard to hide 120db flapping your pants around! I could always tell if it was coming from my left or right when I tried sidewall placement. You may want to consider this. I found mine had to be 15' from me otherwise I knew right where it was.

At the full price of the Danley, and having heard what the Tubas can do, I would build a Tuba. Of course, the Danley kit was.....well, you know.

[tragusa3]

My point was that "very flat" is not what I'm after. I have monster subs because I want monster bass. I think the BFD would give me the ability to put a curve on the subs to my liking. I want to end up with 30hz and below emphasized by a few db.

I'm a supporter of Audyssey, but its goal is flat, not personal taste.

The pair of Tubas I heard were the 36" variety, not 30" as I first stated.

Nice room nyt. I hadn't seen your photos before.

[psg]

Yes, nyt has a nice room. It's his tuba build pictures that go me wondering!

There are only two places a 30-inch Tuba could go, and the 32-inch doors would limit me to that size. I could place a smaller Tuba in each of the back corners, but one of them has only room for 22 inch between the edge of a door and the wall. So even 22 inches is an asthetic stretch and 20 would be better. Unless I build two 15-inch-driver Tubas of unequal width? 20 and 30 inches?

I have some painting to do but I will add squares to a room layout to show you guys. I just realised that they are mistakes on the 3D sketch above; there's not that much spacenext to the back door.

[DrWho]

I'm a supporter of Audyssey, but its goal is flat, not personal taste.

There was an article published by the guys at Audyssey where they detailed how they arrived at their target frequency response, which actually is nowhwere near flat. They actually target a steadily rising frequency response as you go lower in frequency...

I'm not a fan of Audyssey for other reasons, but I wonder if what you were experiencing wasn't due to the modal distribution of your room? One of the interesting things about low frequency content is it requires high frequency content to trigger our ears to listen for it. Low passing a subwoofer...even one with crazy low frequency output makes it sound totally uneventful...it's when you throw in the 30-50Hz body response that the extra low frequency extension starts to reveal its visceral impact...

[DrWho]

You know, I'm told between these subs. It seems like room placement might be the deciding factor.

Ideally, I'd use the two SPUDs as a second row stage, but they could also be along the left wall. The THT would pretty much have to be along the left wall, either half way below the surround Heresy on the other side of the support pole, or behind that toward the rear corner. Which is best?

For what it's worth, I personally would shy away from the Tuba HT
design. In fact, using his own marketing material, he's claiming 111dB
sensitivity from an 18 cu ft design, and compares against a 9 cu ft
vented box pushing close to 105dB sensitivity. The irony is that building two of
the vented enclosures will put you at the same 111dB midband
sensitivity, but then you're not rolling off the low end...effectively
gaining a lot more low frequency extension in the same amount of volume.

The other thing you have to tackle with an undersized mouth horn
design is all of the "pipe resonances" due to the impedance mismatch at
the mouth. The overly smoothed response on his website helps mask the
crazy ripples in the frequency response caused by this, but if you're
unlucky and land those resonances on room modes, then you're going to be
in for a surprise. I guess some people get excited by the crazy SPL,
but it's totally not going to be the same level of refinement that
you're getting from your Khorns. By itself, the Khorn is also way
undersized, but where it excels is in acoustically coupling to the
corner of the room. The difference is that the Khorn flare is being
designed to match the corner flare, whereas the Tuba HT is not.

The downside to the TH-SPUD is that being a tapped horn design, it pretty much requires some amount of EQ to tame the response. But once tamed, you're going to get some crazy impressive SPL...and it's going to be real SPL at the lower frequencies, not just the higher frequency stuff that hits you in the chest. Another artifact that I think (not sure yet) tapped horns inject is that they seem to be a bit slow on transients....like it takes some time for the low frequency energy to build. It's really hard to know if this perception is a result of the reduced distortion, or if it's the multiple sound paths inside the horn that need to be taken, but at the end of the day, tapped horns have a very signature sound to them...well at least the 3 I've heard all seem to have similar sonic artifacts.

That said, I personally would take the tapped horn sound over the undersized horn sound any day of the week.

Btw, you mentioned that you might be doing a second row riser in the room? Have you thought about building a custom horn with a full sized mouth that unloads into the rear corners of the room?

And just another idea to throw out there...have you considered a dual zoned bass array approach? The DBA is the only method I know of that can guarantee to address all of the modal response in your room. I've been dying to try a DBA approach that was built into columns since it would totally hide the subwoofers (if the columns fit the decor of the room at least).

[psg]

Thanks for your lengthy response!

First, I'll say that I changed the image at the top of page two after finding an uncorrupted SketchUp file of my basement.

I have no sub design experience so did no consider the alternative that you mentionned. I am starting a carpentry class next Wednesday and need to show up with a plan on the first day. Thus the choice between existing designs.

Here are the layout possibilities that I was busy drawing up while you were posting. Would the SPUDs be in an adequate location about 4 feet from the back wall?

[nyt]

I don't run anywhere near flat either. I use audyssey to get the baseline calibration in to flat, then just boost the sub channels by X db depending on what I'm listening to... works well

My point was that "very flat" is not what I'm after. I have monster subs because I want monster bass. I think the BFD would give me the ability to put a curve on the subs to my liking. I want to end up with 30hz and below emphasized by a few db.

I'm a supporter of Audyssey, but its goal is flat, not personal taste.

The pair of Tubas I heard were the 36" variety, not 30" as I first stated.

Nice room nyt. I hadn't seen your photos before.

[nyt]

Actually, there is an audyssey thread on the avsforum where audyssey engineers explain it and give support. They dont boost the bottom end, they just taper the top end
at certain frequencies. That's audyssey room mode anyway, since most
rooms aren't treated, they trim the highs so you dont get an overly
harsh sound. Audyssey flat curve, is flat.

I'm a supporter of Audyssey, but its goal is flat, not personal taste.

There was an article published by the guys at Audyssey where they detailed how they arrived at their target frequency response, which actually is nowhwere near flat. They actually target a steadily rising frequency response as you go lower in frequency...

I'm not a fan of Audyssey for other reasons, but I wonder if what you were experiencing wasn't due to the modal distribution of your room? One of the interesting things about low frequency content is it requires high frequency content to trigger our ears to listen for it. Low passing a subwoofer...even one with crazy low frequency output makes it sound totally uneventful...it's when you throw in the 30-50Hz body response that the extra low frequency extension starts to reveal its visceral impact...

[nyt]

For what it's worth, I personally would shy away from the Tuba HT
design. In fact, using his own marketing material, he's claiming 111dB
sensitivity from an 18 cu ft design, and compares against a 9 cu ft
vented box pushing close to 105dB sensitivity. The irony is that building two of
the vented enclosures will put you at the same 111dB midband
sensitivity, but then you're not rolling off the low end...effectively
gaining a lot more low frequency extension in the same amount of volume.

The other thing you have to tackle with an undersized mouth horn
design is all of the "pipe resonances" due to the impedance mismatch at
the mouth. The overly smoothed response on his website helps mask the
crazy ripples in the frequency response caused by this, but if you're
unlucky and land those resonances on room modes, then you're going to be
in for a surprise. I guess some people get excited by the crazy SPL,
but it's totally not going to be the same level of refinement that
you're getting from your Khorns. By itself, the Khorn is also way
undersized, but where it excels is in acoustically coupling to the
corner of the room. The difference is that the Khorn flare is being
designed to match the corner flare, whereas the Tuba HT is not.

The downside to the TH-SPUD is that being a tapped horn design, it pretty much requires some amount of EQ to tame the response. But once tamed, you're going to get some crazy impressive SPL...and it's going to be real SPL at the lower frequencies, not just the higher frequency stuff that hits you in the chest. Another artifact that I think (not sure yet) tapped horns inject is that they seem to be a bit slow on transients....like it takes some time for the low frequency energy to build. It's really hard to know if this perception is a result of the reduced distortion, or if it's the multiple sound paths inside the horn that need to be taken, but at the end of the day, tapped horns have a very signature sound to them...well at least the 3 I've heard all seem to have similar sonic artifacts.

That said, I personally would take the tapped horn sound over the undersized horn sound any day of the week.

Btw, you mentioned that you might be doing a second row riser in the room? Have you thought about building a custom horn with a full sized mouth that unloads into the rear corners of the room?

And just another idea to throw out there...have you considered a dual zoned bass array approach? The DBA is the only method I know of that can guarantee to address all of the modal response in your room. I've been dying to try a DBA approach that was built into columns since it would totally hide the subwoofers (if the columns fit the decor of the room at least).

I see you don't really have any experience with quarter wave folded horns and are just kind of making things up as you go along. These have been measured and tested and there are no crazy ripples that you speak of. In fact the folds act as 4th order filters, and you get far lower THD from a folded horn like this than you do with a direct radiator. You do however, get a slightly rising fr curve which is trivial to eq out. You refer to these as 'undersized horns'. Do you think the tapped horns are doing full wavelength? They're not, and it's not necessary to have a fullsize horn. That idea went the way of the dinosaurs quite some time ago. You also will get cleaner sound from a FLH than a TH, since the 1/4 waves in a TH will not always be aligned, causing more FR spikes. These are more exaggerated in models than they are in practice, but still exist.

Also, according to his graphs, the vented enclosure is at 104db, and his is at 112db, 8db is hardly anything to scoff at. Also, to gain the 6db you speak of you will also need double the power. To gain 8db, you will need more than just another enclosure and double the power.

You also mention transients, however what I think you're referring to is the delay incurred by the length of the horn path. This is typically ~15ms, and with any moden gear is trivial to align properly. Audyssey even does this automatically.

Furthermore, I haven't run into any direct radiators that will hit over 130db at my listening position without absurd costs and insane amounts of power. The THT's accomplish this with ease, and still have headroom to spare. And as for real spl at the lower levels? I think 19hz extension at -3db at these levels can be considered "real spl at lower levels." MKTheater at the AVS forum replaced (8) 18" sealed sonotubes with thousands of watts of power with two dts-10s due to louder and cleaner output.

p.s. look at all the crazy ripples. no smoothing. Also, the top run was clipping my input, since REW can only calibrate input levels so high. I'm not sure where all the horn hate came from.

[nyt]

If you're going to do spuds on the floor, you want them to be nearfield. As for 3 THTs. I think you might be a bit insane. My room is open to 1200sqft and I can't find the limits of two of them without either making myself feel physically ill, or tearing down my house. If those are just different placement options, You'd want to corner load them. Instead of having the two THT's spaced on the right, you'd be better off stacking. One in each of those corners would be overkill. I will say, whichever route you go, whether spud type riseres or THT in the corners, you may end up on your wife shitlist real quick. With the THT's, they play loud enough to literally blur your vision. I've also felt the same effect with a pair of dts-10s. Either way you go, you're going to end up with killer bass.

Where is your screen The notch on the bottom wall?? Without knowing its hard to say where to put stuff, but I'm assuming thats where it is.

Thanks for your lengthy response!

First, I'll say that I changed the image at the top of page two after finding an uncorrupted SketchUp file of my basement.

I have no sub design experience so did no consider the alternative that you mentionned. I am starting a carpentry class next Wednesday and need to show up with a plan on the first day. Thus the choice between existing designs.

Here are the layout possibilities that I was busy drawing up while you were posting. Would the SPUDs be in an adequate location about 4 feet from the back wall?

[psg]

If those are just different placement options, You'd want to corner load them. Instead of having the two THT's spaced on the right, you'd be better off stacking. One in each of those corners would be overkill.

The two 30-inch Tubas on the diagram are just the two possible placement options. The SPUDs may disappear into the room more, but I'm worried that the placement option (or lack or them) may lead to non-optimal placement.

Where is your screen The notch on the bottom wall?? Without knowing its hard to say where to put stuff, but I'm assuming thats where it is.

Yes, currently a 50-inch plasma, but there is room in the notch for the current gen Panasosic 65-inch. I'm thinking a 1:2.35 120-inch screen could drop from the ceiling for projection. Here's what the front wall looks like now (room is not finished yet):

[jason str]

Two Tuba HT of any size would be major overkill for any high performance system in the home, you really cant use all the output, don't be afraid to think smaller if going for the pair.

You may want to block & insulate your floor joists before you install the ceiling to keep the noise and vibrations down.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-570' target="_blank">

[nyt]

The spuds on the floor may end up with a bunch of odd room nodes, but nearfield bass from them will be pretty nice since the idea is to put yourself right at the mouth. Seating further away from it obviously won't have as much of an effect.

If you're doing the spuds, you won't have as much output as a pair of THTs, or maybe even a single? I'm not sure on the exact specs of the spuds, but the dts-10 with two 12's has a LOT more output potential, however those plans and drivers are not available.

I'd go with a pair of THT's if they wont be in the way. They should fill the room nice in the back corners. If it was between the DTS-10 and the THT's, that would be a harder choice

Also, the plans are easy to follow, readily available, and there are tons of pictures detailing the build all over the place, and multiple forums to get help should you run into any snags.

[nyt]

This is true, but a pair will just give more headroom, better dynamics, and help even out room modes.

Two Tuba HT of any size would be major overkill for any high performance system in the home, you really cant use all the output, don't be afraid to think smaller if going for the pair.

You may want to block & insulate your floor joists before you install the ceiling to keep the noise and vibrations down.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-570' target="_blank">