myn's Tuba HT Review (LLT vs THT) - Page 2

I am interested in seeing measurements of the finished speaker. Outside would be nice to eliminate your room.

i sent an email to bfm to let him know about this thread and asked for ground plane frequency response measurements of the tht. if i get any numbers, i'll post them asap.

mynym, if you weren't too far away, i'd help you lug the sub to a parking lot where a good ground plane measurement could be performed.

a second best option would be to put the tuba ht in a spot in your room, take the measurement. then place another sub in the same spot take that measurement. then take the second sub outside and measure it. this would allow you (and us) to have a sense for the difference, which would represent your room gain. we could then subtract the room effects from the tuba ht in-room measurements in order to get an approximation for its ground plane performance. i'm not sure how accurate this method would be for a horn loaded sub though.

third best option. take several different in room measurements. one, mic at mouth of horn. two, listening position with horn facing a corner/wall. three, listening position with horn facing into room.

whatever you post though, know that much gratitude will attend your measurements. there aren't many horn loaded sub builds around, so anything that you provide will be very valuable and much appreciated.

bfm replied. he only pointed to his site and forum though. :-(

corner loaded 24" wide tuba ht frequency response:



corner loaded 36" wide tuba ht frequency response:



general information on the tuba ht:

http://www.billfitzmaurice.net/THT.html

bfm forum:

http://www.billfitzmaurice.net/phpBB3/

I understand, but it's about 10 mins of noise max.


I have always been highly dubious of the charts BF posts for his speakers, so i was hoping for something independent that looks a little less 'hand drawn'. The T24 as measured at the PSW sub shootout bears little resemblance to the posted curves.

you may be faking yourself out.

here is one bfm sub:



here is the exact same sub measurement, but with different scaling (and only from 20-200hz):



the latter can look more "hand drawn" but it is exactly the same thing.

danley does the same thing on his website.

looks like it was the titan 48. it is definitely a different animal from the tht. i simply posted it as an example of how our eyes can sometimes fake us out.

http://www.audioroundtable.com/ProSp...sages/489.html

A9X-308 I believe you are correct.....I just want to get the beast finished as it takes up alot of room in the garage...............

BFM mentions that the 'Titan' series is best for when high amounts of >40hz output is desired and that the 'Tuba' is better for below that. Both are pretty awesome, I say.

I saw several posts by the 'Wii' guy with eight Tuba HT's. It looks as though he loaded them with some JL 13's or something. He does have a pic that is also in his avatar that shows six THT's that have the Dayton DVC's in them. He even has a front access open for a faux-tapped horn kinda thing going. I'd be curious to start off with dual or quad THT's and try corner loading and also try stacking them all right behind my center channel.

you know that you want to scott, so just do it...

4 THTs in a room will give you very impressive low end, and with four you can place them around the room to cancel room modes and have a larger quality listening area, not just one seat. But 3'x3'x2' is a big box.....

With 4 THTs, you should be able to eq flat to 15Hz at reference with low distortion. If you listen below reference, flat to 12Hz with low distortion is a very realistic possibility....

Good news is the 12" Dayton DVC models very well in a THT 16" wide, but loses 3dB of sensitivity....so lose some bulk, lose some sound...with bass, you really can't get something for nothing...

I have asked Bill to design a bigger box than the THT for response below 20Hz (the THT drops off below 25Hz, and utilizes room gain for a boost below that), but he thinks he wouldn't be able to sell many plans.....

If enough of you guys post on the forum that you would like him to design a behemoth, he may do so....I pre-emptively called it a Tuba Cinema...check out the home theater section of his forum...

Here are output meaurements at listening position 11 feet away from horn mouth, in room. I listen at 10dB below reference, so I need 110dB max output, and I cannot tolerate more than 5% THD, so I have highpassed my THT accordingly. These measurements are without any highpass (both TT and THT are wall-loaded):

TT:

12.5Hz-70dB @13% THD
15Hz- 72dB @11% THD
17.5Hz-72dB @11% THD
20Hz- 82.5dB @5% THD
22.5Hz-96dB @5% THD
25Hz- 99dB @5% THD
27.5Hz-105dB @5% THD
30Hz- 106dB @5% THD

THT:

12.5Hz-88dB @5% THD
15Hz- 94dB @ 5% THD
17.5Hz-105dB @5% THD
20Hz- 110dB <2% THD
22.5Hz-110dB <2% THD
25Hz- 110dB <2% THD
27.5Hz-110dB <2% THD
30Hz- 110dB <2% THD

I pushed the 20Hz output to 115dB, and I was still under 5% THD at the listening position. Above 20Hz, 115+dB is easy with less than 5% THD.

Basically, the TT is good for listening at ~15dB below reference, if highpassed at 25Hz. The THT is good for listening at reference if highpassed at ~20Hz, and for listening 10dB below reference, highpassed ~16Hz, with a little boost to the sub-20Hz frequencies to make sub-20Hz response flatter. Both boxes need eq, just like any sub in a small room.

My TT has the MCM 8" driver, my THT the Dayton Reference HF 15" driver...I am waiting for myn's sub-20Hz output and distortion results to see if a Dayton DVC migh find it's way into my THT...

JSS

Wow, I mean WOW. You get a ton of room gain by the looks of that graph...My guess is that the sub-10Hz measurements may not be as reliable as above 10Hz...My RS meter was the same way, my Galaxy meter is much better behaved...

I would expect as the volume goes up, the sub-20Hz portion will not rise as quickly as the 20Hz and above portion, as sub-20Hz is below horn loading...

My sub measures like so: dark green with eq, light green without. The dip is a room artifact, it becomes a boost by moving the listening position a foot and a half or so...still, that's a +/- 5dB graph from 15 to over 100Hz....it's actually a little worse, this is 1/3 octave smoothed...



But I saw the pics of the construction of your place...much more solid than the sheetrock/stud/osb/siding combo I have...which means more room gain for you...

JSS

Wow, Mynym!
You've got significant output all the way down to a single Hert (que the laugh track). Well, I thought that sounded funny. Okay, I guess I need some coffee.

If you still have the measurement file handy could you tighten up the axis a bit and re-post it. It's tough to tell what's going on with the range so big (140dB to -60dB). Like others have said you might as well cut off anything below 10hz too.

Agreed. Here it is scaled to Maxmercy's graph to 10Hz (I wouldn't trust anything below that):



Bosso

My THT's mouth is against the wall, about 3 feet from a corner, and that corner has bass trapping in it, so I'm not sure how much that affects things...

My house does not give much room gain, either. I expect your place to have lots more gain down low, with the cinder block construction...

I am eagerly awaiting your distortion measurements...according to hornresp, below 20Hz should be close between the Reference HF and DVC, but above 20Hz, it is all DVC, as the DVC has a 3dB efficiency advantage...

Bottom line: For the money, the THT is the best thing going that I can think of, subwoofer-wise. If someone else has a sub they made or bought for less than $450 (with amplifier) that can belt out 115dB 11 feet away with less than 5% THD, I'd like to know. I'm sure there are some tapped horn designers who could get something like that, but most folks don't want to design something from the ground up...the THT's instructions are very good...

JSS

I'm in.
I was persuaded early in this thread.
But, what sealed the deal was your post of the TT/THT data (post #44).
The only reason I haven't placed my order yet, is I need to compile a shopping list for PE.
I'd better hurry though, I have a feeling that the Dayton DVC 15s will start flying off the shelves soon.

I got wood already.
Let me rephrase that.
I got plywood.
Thing is, I have some other projects in line, but it is hard not to get excited about this.

The DVC is an awesome driver yet so often overlooked. It has strengths that you just don't find in the exotic flavors of the month club drivers. This makes it good for a few applications that aren't necessarily obvious to the casual driver searcher.. or the flat simulation response searcher.

Just sayin

I bought the plans already. For some reason I have the itch to build something else and this will be totally different than anything I have ever done.

I most likely missed it, but what is the amp that you are powering it with?

Is it reasonable to expect (based on the strong points of a THT versus an LLT design) for the THT to perform better than the LLT in the sub-20 Hz range, given similar box sizes for both ? For a reference point, how do they compare at a box size of 25 ft^3 = 707.921 liters (given sensible choice of drivers for both designs) ?

Mynym,can you post the dimensions of the Tuba.