Recomended Eigtheensound driver/horn?!?

I recommend all the 18Sound horns! They're great!

What ever speakers are used, if it's passive, the success of box will largely depend on the balance brought about by a finely tuned x/o.
A 2x12 mid will probably suffer from phase cancellation in the upper frequencies of the 12's, and there's no easy cure.

Tony, do you ever do 2.5 way crossovers? I mean if you've got a dual midrange, roll off the bottom one lower than the one closer to the HF so that only one driver is covering the region where it crosses over to the HF? Since a lot of drivers having a rising response you might get a flatter response?

Chris, I've never done that, but just to clarify, I was referring to the upper part of the 2 X12 regarding phase issues. It's the upper part of the 12's that go out of phase with each other when they are close together.. You may well have realised this, but I wasn't sure.

so...to resolve the phase issue should be nice putting a panel between the 2 woofer to divide the horn mouth?

When I first looked at the drawing which was for about 10 seconds, I saw it as a straight baffle front loaded reflex job. It just goes to show what a plank I can be sometimes. So, I guess the division separating the speakers is the answer.
I have mentioned before, that there is a point between 2 speakers where coupling ceases to be obstructive and becomes productive, I always meant to attempt to draw a graph indicating where the crossover point might be. I think the difficult part is the fact that, although frequency doesn't alter, I believe the size of the speakers play a roll in the effect. This is because of the beaming effect, which happens when the length of the frequency being played reaches the piston diameter of the speaker, therefore, a 10" speaker will play much higher before beaming occurs compared to an 18"speaker where beaming would occur at a lower frequency
My point is, regarding the coupling effect, is that I believe it would happen at different frequencies according to what size speaker is used. Perhaps the answer is to calculate at what frequency a particular speaker will beam, calculate the length and make the dividing wedge slightly longer than the figure. Someone who knows more than me may have a better answer.

In your opinion, what type of driver works nice in this cab?
I've heard someone that use b&c pe32

Thinking of doing a half version of this, one driver. I'm never sure about flares that don't go inside the diameter of the driver though. Is there any point?

sim soon to come.

smt212 (only mid section)
s1=2172
s2=4120
con=29.2
vrc=23.8 (with driver)
lrc=17.3
vtc=44107 (with driver)
atc=1048

there are 2 air port but I don't know to obtain combined response with directivity, however
ap=72
lpt=1.6
path lenght difference= 33

Probably I'd go for 2 single version without port with an altec 811b horn on top in a separate cab.

Ta.

Built and tested 4 single smt212. Just B&c 12" driver in one cab. So portable so loud. I've modified the port shape mantaining the same area, 2 quarter circle instead of 2 triangles. Just estetic reason

Pics?

Sorry, I don't pics of only the smt, only the whole rig..however I've posted it on show off thread. Don't want to hijack the thread.

cheers.

FAILURE- They dont offer 15mm ply where i am, so i tried using 1/2", but its not gonna work. I have to use 3/4" (18mm). anyone else have this problem?

tony, would placing the HF section in the middle fix the phase problem you speak of?

Long time no action on this one. I had to go back and see what we'd all been talking about. Because I know that two speakers, especially mids, react with each other when they are close, it's logical to assume that if you pull them apart, it will have an effect. I often build test boxes to try all sorts of things, so it it easy to establish certain things. You would have to have some sort of measuring equipment, or perhaps something as simple as a Spectrum analyzer.
All you need to do is put the pink noise signal into both cabs watch the screen and start to move then apart. To make reading easier, if you have an equalizer, it is better to make the speakers as flat as possible, and watch the change in response as you move the boxes. You could simulate the position that the speakers would be in the cab. This would be the best way to find out.

i dont have any such tools, but thought it might make a difference. when i build a full smt212 i will give it a try, cant hurt can it?

Hi, horn section, what kind of driver shall I use with Altec 811b. Is there any other good horn+driver set?

Any one using this design in live combat? To quote the other half "It Look Nice" end of teccy conversation. I have always gone for an 8" and a 12" on the Mid section. Anyone using it Live? Small pub or social club type gigs? whats it sound like when its knocked up? and properly finished?

Like one of the earlier comments 15mm ply difficult!

I have 4 of these with PDN12SB30's and Fane CD250 2" CD's with Fane horn flares and they are awesome.

Thanks Cozy Pillow - thanks for the info Thays what I wanted to here ! My wife wants two co\ they look nice ! end of teccy discussin! I fancied something a bit more helpful either way b4 commiting to a bulid a bit later. Like Mautopsy said 15mm Ply is a bit difficult here and I done fancy the idea of MDF.. 1 I don't like the dust problem... 2) I've never had any luck sealing preping the surface to take a finish (Paint/Glue etc) I might just have to rethink the strategy if I cant find a design in 18mm

come on... it's a cab with only six panels. It's easy to adapt to a 18mm thickness.

Hey Bitzo I'm a complete newbie at this I don't mind admitting it so I have to bow to your greater knowledge!Its a bit daunting to someone never done it b4. If it comes together I'll be the first to turn to guys like Cubo and yourself and say Thanks M8 you were right!! I'm willin to learn and have a go, so far I've had Good advicem encouragement and frienliness here! if I ask the "Baby" questions its coz I don't know!! Have a Happy (and healthy) new year and 2012. I will keep you updated! Cheers m8 Have fun Dave and Luz Manila Philippines !!!!

With respect, if you are worried about sorting the difference between 15 and 18mm, then a simpler build frst time may be an idea?
There are angles to consider on this one too.

Good point Nicky! I have time to play coz I am retired. so it don't matter but if you got a good one in mind for the numpty point me at it I've not committed yet!

Nicky Better reply for you. Ply 8x4x0.75 is 14.00gbp a sheet I've got to learn! from Ace Hardware to a small backstreet construction supply it is PLYWOOD dont ask or try to specify It is PLYWOOD one product! this ain't the UK with many different grades. cutting is 5 to 10 peso a cut locally on a table saw (8 to 16p/cut) so not over worred I can screw glue seal ok if the panels are square. Like I said Willing to learn/have a go I'm an electrical Tech by trade and a radio ham so just woodwork that is my weakness (if u know a better design I'll Look at it! Cheers/Tnx DAVE B!

Try to re draw it in the original version with a software. If you're able to use cad there's no problem but you can use inkscape too (it's free and simpler to learn). Then make the mod that you need paying attention to keep the internal measures of the horn and of rear chamber.

I have it Bitzo thanks! I'm cuttin me teeth on some cubos at the moment while i'm doin that i can be sourcin ply see if I can find 15mm if not then Inkscape here we come

15mm birch 32 pound a sheet

pm me if you want any

Thanks SMT12. Zhere are you for transport? Luzon, Visayas or National Capitol Region!! HAHAHa theres no way I a, going into Mindanao region at themoment untill the travel advisory is lifted by the embassy in Taguig so Davao city is defo out lol

Hang on a mo... proper ,money, Wheres me calculator.. 65.44 so ..2094 php She gonna go nuts HAHAHAHAHAHAHA I aint done a cut list yet but two should come out of 1 sheet cheers Happy New Year everyone

OK Does the team think. Another 5 construction suppliers today, results as follows 8x4 sheets 10mm = 570peso or 8.56gbp. 18mm = 950peso or 14.42gbp. So we have to adjust the plan unless Ace hqve 15mm/0.5 inch. Initial thoughts. 18mm, construct as plans. If I use 10mm then a lighter cab that may need extra bracing ok for home use but mobile ??? The bracing would affect the chamber volumes and hence tuning/Performance. Any thoughts anyone?? On cost alone then the 10mm option and strengthen it up q bit ! Any thougths fro, the experienced ? Exchang rate correct at time of posting 65.88 Yes I know its DIRE !!!

Just looking at the design and wondering if either Michael or Tony came to any conclusion about separating the drivers and if it's better/worse?