DIY bass horn build...Up next - Page 4

eyeballing from afar - trying to get a phase match

There is a disconnect, but it isn't that bad. All DSL ratings are based on 2.83V=1W regardless of the impedance of the sub.

As you have posted this means you have to convert the sensitivity numbers to a true 1W number. In this case ~105 is correct.

The hitch is that no ones models every hit this number. If you do everything right, and the FR, Phase, and Impedance graphs line up, the best you can do is ~-3dB from their posted numbers. Case in point if I put 2.83V into my TH118 sim(s) I get 105dB out. (This is not the case for the two SPUD models though.)

This has popped up several times on other forums, but nothing concrete has ever been found out. The only thing TD has added was that the sims must be corrected to what is measured.

The DSL exact measurement setup is not known, but the Subwoofer Shootout 2007 methods where published, and the TH115 numbers matched up. It was measured inroom at 4ft though.

I have never seen anyone put 2.83V to one and measured the results, or have had the chance to do so myself. I figure there is one of two ways it will go. It will either hit the numbers, or it wont at 2.83V but will at 28.3V.

EDIT: There is also the Pink Noise factor. I do believe they will hit what they say they will. Informal testing with a TH412 paned out at 110dB/2.83V.

Neo Dan,

Remember to account for the wood. Just accounting for the exterior 18mm panels leaves you with ~357l interior before adding any other panels, or wasted corner space.

I would check out some of the newer 18" drivers as well.

The chart does say 100w. I'd chalk that up to a measurement error, taken at 28v instead of 20v, as the response is definitely 3dB higher than one could expect.
That still leaves the sensitivity at least 6dB higher than Ricci is looking at, and that boils down to it being a tapped horn and the driver being a pro-sound model.

here is a snip from the spec sheet. like bfm confirms, it definitely shows 100 w not 28.3 volts.

that might explain 3 db, but we are still way off.

bfm, your tht horn and ricci's horn have a very similar frequency response...+/- about 1 db or two. both are "at the performance boundary" horns. ricci's design has greater performance at the limit, but at an increased driver cost.







"Calm down there LTD..."

ok, i've just become overly sensitive to b.s. sorry for blowing my lid in your build thread. ;-)

"A nominal 2 ohm cab will look much better with a 2.83 volt input than a nominal 8ohm cab, but the 8ohm cab may in reality be the more efficient one."

+1. i hope the lurkers look into this. constant voltage will produce larger current the lower the resistance/impedance. after adjusting for all this, i don't see how one gets more than about 96db 1w1m out of a cab this size at 40hz. the 105 number is b.s. in my estimation.

It looks fine. It is about as compact as it is going to get I think.

I have a snail version, but it has the driver vertical in the upright position. I haven't bothered to check on the sag factor here, I must admit though.

soho, since you are the guru, could you model up the final build plan?

it would take me several hours to try to calculate the specific final dimensions. you seem to have a much better grasp on getting to the final dimensions than just about anybody around here.

All of those PDFs with those style graphs say that. As I said all DSL numbers are referenced to 2.83V=1w. They want you to look at the impedance/ohms and come up with your own 1/W,1/M numbers, as there is no exact way to do it.

the th-50 numbers look much more realistic to me.

I can't keep up with the edits.

I have several THs simed in slightly smaller packages that can hit 100dB at 40Hz per a true 1W/1M 1/2 space. It isn't that hard.


That is the other one that you can sim up exactly.

"I have several THs simed in slightly smaller packages that can hit 100dB at 40Hz per a true 1W/1M 1/2 space. It isn't that hard."

with a 25-30hz corner???

shoot me thems designs!!! ;-)

back on topic...have you got ricci's back with respect to the final fold plan dimensions?

i'm 'almost' just as curious as ricci is to see what you can cook up.

Ha, I wish. More inline with the TH115 and TH118 talked about above. Getting withing 3dB of the DSL corrected numbers is not that hard. It's the extra 3dB in some of them that bugs me, one day I'll get around to testing, just need to have some DSLs around again.

I'll be happy to help however he wants me too with the folding.

"I'll be happy to help however he wants me too with the folding."

soho, you are the man. probably the only guy who can accurately provide a fold plan for the ricci lms horn. i may be able to do it, but it would cost me hours of time. :-(

unlike so many other mockups that you have done, ricci will actually build it!

There are only a couple ceramic motor 18" drivers in the B&C lineup - the TBX100 has the highest power rating, that said it would have to be a 4 ohm version I'm not 100% certain that it exists as a stock driver - it might be custom.

Also I have to wonder about the ability of Hornresp to accurately model these types of systems where the mouth is so undersized in comparison to the line length and it's low end cut off. I also happen to think that small mouth designs like these where the exit is effectively loaded by the ground and the upper portion of the box effectively creates a mini 1pi like loading - or end correction if you will. I don't think there is any accounting for this in Hornresp.

The driver shown in the PDF is not the driver that is shipping with it. That I have seen.

Here is a TH118.


This driver can handle 3600w.
The B&C 18SW115 is nice too.


The mouth correction is applied correctly in HR. There was a big ta due about it over at DIYaudio a couple years back.

Perhaps, I haven't compared them closely. But THT is an HT sub, not intended for pro-sound use, designed and loaded accordingly. T60 is a pro-sound sub with a 28Hz Fc, and it's a big sucker. But if you really need to go that low for high output pro-sound it's not going to be small.

Panamera Turbo with sport chrono package 0-60 in 3.8 seconds vs CTS-V's 3.9 seconds only Panamera has twice as much room front, back and in the trunk and it has twice the luxury - 8 way power REAR seats anybody ?

Any idiot can make a fast car. The point is to have the complete package.

My friend just bought a Pontiac G8 GT which is a similar type of car to CTS-V. There is no GPS ( even as an option ). The seats aren't fully powered ( driver's seat ! ! ! ), there is no backup camera, no parktronic etc. This car is typical of the way Americans make cars - there is one or two features that sell the car ( usually either styling, or horsepower, or room ) and everything else about the car is garbage.

Germans make cars the opposite way - they make sure EVERYTHING about the car is as good as it can possibly be - engine, transmission, suspension, styling, seats, sound system, safety features, GPS etc.

The reason my friend didn't get a CTS is because he is a big guy and CTS is uncomfortable for him. He got a G8 because its big, now he is suffering with all its inadequacies.

With Panamera Turbo he would have had all the room, all the performance and all the luxury he wanted but of course he couldn't afford one. For that matter he couldn't afford ANY German car. He actually loves German cars and ever since he once had an audi he only wanted to drive German again but he knows he cannot afford the maintenance costs. He told me all this himself - it is not merely my assessment.

And it's a hell of a lot more expensive.

i made a mistake panamera doesn't really have power rear seats.

on the luxury side porsche trails BMW problem is that BMW isn't faster than CTS-V.

i guess you win for now ! let's hope when the new BMW M5 comes out ( any day now ) it rips your CTS-V a new one. I agree it was quite embarrassing when your CTS-V defeated us

Sneaky sneaky, thanks for the heads up. I'll see what I can dig up

there is a woman standing outside the sprouts food market in sunnyvale california with a sign saying "need tipper for food". now aside from the fact that i have no idea what language "tipper" comes from she is obviously homeless as she hauls around a HUGE cart of *stuff* and she is there every day all day just standing in the same spot.

so i have no problem believing that she needs the money. problem is that she is 4 times my size. i never gave her anything because i just don't understand why i should feed somebody who is overweight by 150 pounds.

so i thought to myself - how is it possible ? how can a person be so poor and so fat at the same time ? don't americans like to say that they are so fat because of their affluence ? and then one day i had my answer - i saw her standing with a 2 liter bottle of soda drinking it straight from the bottle.

so she is basically filling herself up like she was a diesel truck - liquid energy by the gallon. no nutrition - just calories. i am willing to bet she is also severely malnourished as she probably never has any real food like spinach or salmon.

the problem is i used to eat the same way she does, and i couldn't control my weight even while constantly crash dieting to ( literally ) passing out and working out for hours every day. why? because when you walk into a supermarket those junk foods are the only ones there. in the entire walmart there is nothing, and i mean NOTHING that truly qualifies as food - only junk. and then americans wonder - why are we so sick ?

i am now at ~30 y/o in better shape than i was in high school simply because i stopped eating ALL american food a few months ago which resulted in me dropping 45 pounds so far since march. and i don't have to do anything ! i don't have to diet or exercise - simply by switching from poisonous garbage to real food ( fruits, vegetables, fish and organ meats like livers, kidneys etc ) the body is normalizing all by itself.

i have tried various diets in the past and failed every time. because all those diets are just running around in circle - substituting one sh1t for another sh1t just like when you switch from republican government to democratic and back. the solution was to realize that it is ALL sh1t. ALL american "food" is actually SH!T and it is getting worse ever year at breakneck speed i might add !

so yeah lets face it - everything about America is garbage - the food, the cars, the government. America is doomed.

here is why i am not going back though. i came here from the soviet union shortly after it collapsed ... and now USA is collapsing. what's the point of me going to some other place when chances are it will go down in flames as well. i need to maximize MYSELF in the environment i am in, not try to run to a better place hoping all my problems will be solved for me by others.

because ultimately it is all relative anyway. you can't have most of the things you can have in US in other places ( like cars, houses etc ) but you also don't feel the need to have those things there. so even if one country has 10 times the GDP per capita than anther that doesn't in itself guarantee that the people are happier on average. poverty is perceived only in relationship to the rich - there is no absolute scale for it. you could say people in africa are in poverty because they can't afford food or you could say that people in america are in poverty because they can't afford to pay for their gastric bypass surgery.

but since most places have their own ups and downs on the average i would still rather live in a country with high GDP per capita like the US. that doesn't mean i can't judge what's wrong in this place.

the whole "if you don't like it here go somewhere else" mentality is ***ing idiotic. this is nothing more than nazi-style propaganda shoveled like sh1t by the government and shoved down the throats of the dumb swine. that's like saying if you crashed your car - get a new one. no that's not the answer. the answer is if you crashed your car - maybe its time to learn how to drive ! your logic is what produced wonderful places like nazi germany and wonderful developments like WW2, Vietnam, Iraq etc. whenever you stop being critical of yourself you turn into a piece of sh1t - that is equally true of a person and of a nation.

so go ahead - keep up your phony patriotism and watch US follow the fate of the soviet union.

i am not afraid of the collapse of US - that much i have already accepted as inevitable. what i am afraid of is of the collapse of western civilization altogether. look at what happened to Rome and Latin language - the same thing can happen to the entire English speaking world. History ALWAYS repeats itself and arrogant pricks always think THEY are special and it won't happen to them. So far there haven't been an exception - not a single empire that didn't collapse. If you ask any American what caused the collapse of any other empire they will stare at you and blink as if saying "why on earth would i need to know that" ? well i will tell you the answer - they all collapsed because they didn't ask themselves that question.

Damn ,I would buy your plane ticket if you never post again


Posting on here and elsewhere is not maximizing ANYTHING, get a better job or build a business...that would be maximizing something!!!

Can we get off car topics and now politics? I like following Ricci's build threads for the audio science portion!!

the pontiac g8 is basicallly a Holden car. Holden is an Austrailian car company.

for the record.

Ricci,
It's no fun to give all the info away. Half the fun is digging around for it yourself.

Per post 115.

Yeah, me too. With the snail you would have to tip it on its side like the TH221 to have the driver in a neutral position.

The folding is no problem. If you are still happy with the original model more or less it will not take too long. LTDs fold is half way there already.

The black sheep of the family...
After looking here I think something like this would be easy. I think they are missing a bend in the horn though... LOL at the suggested 4 ohm rating though, I'll try with 8Ω drivers.

it seems that the higher corner is most of the answer that i had missed. as you note, the shorter length allows for more mouth area holding total volume constant. the scale chosen on the danley graphs makes it hard to see what is actually going on and i got faked out. i understand that sensitivity appears to increase 3db each time impedance is cut in half and even though it says 100 watts, it is 28.3v. another couple db may come from, in part, atmospheric conditions. temperature, pressure, and humidity all affect air density. maybe there is a "good" type of day to take measurements on. :-) maybe there is also something in the nature of the signal that is used. with the increasing amount of measuring that is ocurring, it probably won't be too long before we see some independent confirmation.

as for the th218, that is a large horn. for the home, most folks would probably be better served by chopping it in two. just in case scott is getting ideas. :-)