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Variation of SMT-212

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Forum Name: New Projects Forum
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Printed Date: 29 March 2024 at 11:57am
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Topic: Variation of SMT-212
Posted By: Fracture_clinic
Subject: Variation of SMT-212
Date Posted: 29 March 2019 at 10:05am
Good morning all,

I've begun a little project of making an SMT-212 variation.

Its going to feature a single 12 inch section, a stand-alone 8inch section and a 1 inch HF.

bevelled all the 22.5 degree angles the other day, yesterday the 12inch baffle got routed out.

Next up is the cut outs for the horns.

We'll be measuring the output once it's all done and hopefully getting it dialled in.

Probably going to aim for tri-amping, comp choice depending.

Ignore the weird perspective..




Replies:
Posted By: sushi
Date Posted: 30 August 2019 at 5:29pm
Interesting project!
I'm about to start to build another SMT212 variation too, i'm going for the single 12"+ hf driver..
What 12' speaker are you using?
I'm searching for some Eighteensound 12nd710, as Stiper himself suggested as suitable driver.. but they are unluckily out of production, i only found them for sale on Thomann for 300 euros each.
On the other side, two models from new Eighteensound catalogue looks suitable for the job.. i'll choose from 12nd930 and 12nd610.
I see you posted in march.. did you finished your cabs? Looking forward to see them done! Cheers


Posted By: Fracture_clinic
Date Posted: 30 August 2019 at 5:43pm
You've actually caught me on a day where I'm back up and running after getting side tracked on a camper van conversion. I've been doing little jobs for the top. Made the handle boxes and they're going to get mounted in in the next week. Annoyingly the 1inch horn I used in the design and planned around has gone out of stock and doesn't look like it will come back either. I'm going to use the RCF LF12g301 i would use the MB12g301 but I want to be able to cross the tops straight into scoops sometimes.

I'll crack on with a few more jobs and get some images soon for an update.


Posted By: nkdk
Date Posted: 31 August 2019 at 3:48pm
#sushi
The 18s 12nd930 sound very good, but you can use at lot of other drivers, and not that expensive.
In my smt212 i use eminence kappa 12,and rcf n850.
Just go fore high sensitivity >100 db
nkdk


Posted By: Fracture_clinic
Date Posted: 31 August 2019 at 8:00pm
Originally posted by nkdk nkdk wrote:

#sushi
The 18s 12nd930 sound very good, but you can use at lot of other drivers, and not that expensive.
In my smt212 i use eminence kappa 12,and rcf n850.
Just go fore high sensitivity >100 db
nkdk



12MI100 beyma if you want high sens!


Posted By: sushi
Date Posted: 03 September 2019 at 12:31pm
Fracture clinic: I actually did consider the option of using MB12G301 (which seems suitable for the SMT) but after a while i decided to spare money to get a pair of 18sound drivers.. just for higher sensibility. now i'm deciding between 12ND710 and the new 12ND610.

Nkdk: i have a pair of kappa 12a! I already planned to give them a try but i was quite sure they were not going to work well inside SMT's small chamber.. how do they sound? Please let me know! Thank you for the advice about Beyma, i'll give a look at the specsheet!


Posted By: Fracture_clinic
Date Posted: 03 September 2019 at 1:43pm
Originally posted by sushi sushi wrote:

Fracture clinic: I actually did consider the option of using MB12G301 (which seems suitable for the SMT) but after a while i decided to spare money to get a pair of 18sound drivers.. just for higher sensibity. now i'm deciding between 12ND710 and the new 12ND610.

Nkdk: i have a pair of kappa 12a! I already planned to give them a try but i was quite sure they were not going to work well inside SMT's small chamber.. how do they sound? Please let me know! Thank you for the advice about Beyma, i'll give a look at the specsheet!


Both very good drivers, if I were to spend that much I'd pick the 12ND610 out of the two personally.

qts of 0.14 swings it for me.


Posted By: sushi
Date Posted: 03 September 2019 at 1:52pm
Yeah, that's an interesting point, together with 102db sensibility and 24 BL factor. They are for sure one of the best midrange drivers out right now..
The best thing about that is that here in italy i can get them for about 250euros each, on the contrary the 710's are available only on thomann.de for 300euros each (unless you make a special order directly to 18sound)


Posted By: Fracture_clinic
Date Posted: 03 September 2019 at 2:27pm
Originally posted by sushi sushi wrote:

Yeah, that's an interesting point, together with 102db sensibility and 24 BL factor. They are for sure one of the best midrange drivers out right now..
The best thing about that is that here in italy i can get them for about 250euros each, on the contrary the 710's are available only on thomann.de for 300euros each (unless you make a special order directly to 18sound)


Ah I think we have a winner then?

The original driver was SN12B iirc, with a qts of 0.16, BL over 20 and vas of 83


I know the 710 is recommended but all things concidered (higher sens, more similar BL and qts to SN12B, cheaper price and ease of acquisition) the 610 sounds perfect. Some may grumble at the slightly lower xmax, but there's more to life than xmax ;)

I'm really interested to see your SMT develop. I'll grab some pictures of mine soon. Have you built yours?


Posted By: sushi
Date Posted: 03 September 2019 at 5:24pm
Naah.. still wasting my precious time with my job, been a busy month.
However, i already made all the drawnings with CAD, and started programming the CNC: a friend of mine has the machine in his woodworking company, he's going to help me.. i worked as a carpenter some years ago and have already some experience in building speaker boxes, but this is my first time working on the CNC (i used to bring plans & plywood to my ex-boss, and then assemble everything on my own). I'm buying the wood sheets (250x125 cm) next week, but i don't think the cabs are going to be finished until october. I'll put some pics here!

How many sheets did it take to build yours??


Posted By: godathunder
Date Posted: 03 September 2019 at 6:00pm
As a matter of interest, are you taking the stated sensitivity from the spec sheet or taking it from a  frequency / sensitivity graph?

-------------
LOUDER THAN LOUD


Posted By: sushi
Date Posted: 03 September 2019 at 7:31pm
I saw both of them.. well, the sensitivity rate is a general parameter that have a fascinating power on the buyer, but the graph gave me some better reasons to buy. since i'm going to use the speaker in a midtop cab, crossed at 2.9khz with a horn loaded compression driver, i think it's going to work fine in the frequency range that i need to cover.
Anyway, it's my personal belief that good sounding speakers sound good in real life not only on specsheet. In other words, i would wait until i test them in the cab to say "yea dude 102db forrreal". As long as i heard 18sound speakers are clear sounding powerful and loud, which is why i decided to try them. If the 610 would not satisfy me in the midbass range, when crossed around 200hz with ESW1018, i would use HD15 kick bin for the range between 100-300hz.


Posted By: Fracture_clinic
Date Posted: 03 September 2019 at 10:11pm


So here is the mid top without the 8inch or 1 inch horn mounts cut out and shown relative to my mini scoops. That's scoop number three half way completed.

I would cut the horn baffles but I'm waiting until I actually have the horn in my hands,, which may not happen as I've emailed every known supplier and can't find them second hand :(


Posted By: sushi
Date Posted: 04 September 2019 at 12:23pm
I think the SMT gonna look good! I saw a similar project on google images, black painted, with the midhigh and high section very lookalike the tms111..

What about delays on the bass? Considered that the 12 woofer and the hf driver are alligned (in my project) should i use a delay on subs, even if the hornpath of the midtops is not longer than 30 cm?
I think i should do some maths and calculate the right delay


Posted By: Fracture_clinic
Date Posted: 04 September 2019 at 2:02pm
Originally posted by sushi sushi wrote:

I think the SMT gonna look good! I saw a similar project on google images, black painted, with the midhigh and high section very lookalike the tms111..

What about delays on the bass? Considered that the 12 woofer and the hf driver are alligned (in my project) should i use a delay on subs, even if the hornpath of the midtops is not longer than 30 cm?
I think i should do some maths and calculate the right delay


To answer your question I'd need to know what subs you're using. The tops may still need a few m/s delay even between the 12 and HF.. when I say need I mean could be done, whether it makes an audible difference is another matter all together. Typically you would be delaying the mid-tops to the subs. If you have reflex subs then maybe the other way around.


It will also depend on how many sub you have and their group delay. Which will depend on your chosen pass-band also.

I will measure and delay all three sections of the top using a mic. As for my scoops, well they never behave. Generally the phase on the scoops is flipped 180 degrees.

The only way is to measure and align, using horn path length doesn't always work.

you can use pink noise and polarity flip to do it by ear, but I'm not very good at that.. ravers ears, so I'm tone deaf.


Posted By: nkdk
Date Posted: 04 September 2019 at 2:19pm
#sushi
Actually the kappa are doing it  very vell, and thy go down to 70-80 hz,an give a good kick.
i think they are worth a try,
If you live in Italy and you can buy the 18s to a god price i would  go for them.
nkdk


Posted By: sushi
Date Posted: 04 September 2019 at 8:48pm
#Nkdk
I will absolutely try them! I love the Kappa12A, they gave me some serious satisfaction for my first build, and Eminence still means good sound at good prices for me (i got Kappa15LFA and PSD2002 as well) I'm buying 18sound anyway cause i'm trying to sell the kappa12's with the midbass cabs i built for them, old school mid horns with two round panels beside the speaker, sound great but they are 84cm wide.. they really look enormous on my kicks and subs, would need a larger sub stack under them.. something i can't afford right now

#FractureClinic
I'm going to stack the SMT's on a pair of RCF ESW1018.. not a proper sub but since i'm mainly playing hardcore tekno, crossbreed neurofunk, i'm quite good with them. I just put a 40hz high pass (my plan is to build 2 more,but maybe one day i will build proper subs and use the ESW only for bass range) They are front loaded and have a large reflex port. Look like the miniscoop but have a slightly shorter reflex horn.
I have also HD15 kickbins that i'm gonna use in case the midtops are not doing well under 300hz, but they would need a delay set on subs because of the horn, plus a shorter delay set on midtops.. actually, i don't know the correct delay to set and neither i know how to calculate it for reflex horn cabs like mine. At least i have DSP on my amps so i could set different delays.


Posted By: sushi
Date Posted: 04 September 2019 at 9:17pm
Originally posted by Fracture_clinic Fracture_clinic wrote:

Typically you would be delaying the mid-tops to the subs. If you have reflex subs then maybe the other way around.


It will also depend on how many sub you have and their group delay. Which will depend on your chosen pass-band also.


I would like to understand more about this point.. how do reflex cabs behave? Why should the midtops be delayed?
Thank you, by the way.. this conversation really starts being inspiring.


Posted By: Fracture_clinic
Date Posted: 05 September 2019 at 8:31am
Originally posted by sushi sushi wrote:

Originally posted by Fracture_clinic Fracture_clinic wrote:

Typically you would be delaying the mid-tops to the subs. If you have reflex subs then maybe the other way around.


It will also depend on how many sub you have and their group delay. Which will depend on your chosen pass-band also.


I would like to understand more about this point.. how do reflex cabs behave? Why should the midtops be delayed?
Thank you, by the way.. this conversation really starts being inspiring.


Let's say you only have two ESW1018 per side and some horn loaded mid tops, like something with a long horn, not a 'pseudo' horn like the SMT 12 inch section (which is more like a wave guided reflex)..

Your subs are in front of the stage and your tops are up on the stage for some live music work.

You might find that the group delay on a pair of ESW1018s is for all practicality none existent.

So due to the mid-tops being horn loaded and set nice and high for projection, their sound takes a little longer to reach the listeners ears so you would need to delay the subs. The subs are also physically a little in front of the mid tops.



You mention you have HDs also, so let's thrown them into the mix.



So same set up as before, you have a stage with your ESW1018s on the gound infront of the stage, two per side. Only now you have a pair of HDS under each top up on the stage.


First things first you'd likely want to flip the polarity on the HDs if theyre not already reverse wired. (Don't reverse wire them, or any bin for that matter, do everything at your LMS if you can).


Now your mid tops are even higher (not by much so let's just say it doesnt make a difference). But what might be more important than delay now, is phase alignment at the crossover points. So in this situation that might be more important to you than delay. From what I gather phase and delay crossover, excuse the pun, somewhat.


I'm still very much on the learning curve so please don't take what I say as fact, mearly my attempt at taking some of the things I've learnt on here and trying to give back to the community.


What I would say is keep reading, there are long threads in the deep reaches of Speaker PLans with some awesome information.


Posted By: nkdk
Date Posted: 05 September 2019 at 2:42pm
#fracture
I hope your planning to make vents fore the driver,its a very small chamber
nkdk


Posted By: Fracture_clinic
Date Posted: 05 September 2019 at 6:52pm
Originally posted by nkdk nkdk wrote:

#fracture
I hope your planning to make vents fore the driver,its a very small chamber
nkdk


Yeah I will do, to the original port spec too. Four 1 inch holes is practically the same as half of the SMT212's port volume.

But first I'm going to load it without any holes and measure it and then do a before and after, just because why not really.


Posted By: sushi
Date Posted: 05 September 2019 at 8:26pm
#Fracture_clinic
Ok i understand the first part, it's quite basic..
But i think i have some doubts on reversing the polarity: what's the effect it does? Have the polarity anything in common with the phase?
I don't know what a LMS is but i imagine you're talking about a sort of processor.. is it so?


Posted By: Fracture_clinic
Date Posted: 10 September 2019 at 1:41pm
Originally posted by sushi sushi wrote:

#Fracture_clinic
Ok i understand the first part, it's quite basic..
But i think i have some doubts on reversing the polarity: what's the effect it does? Have the polarity anything in common with the phase?
I don't know what a LMS is but i imagine you're talking about a sort of processor.. is it so?


Reversing the polarity has the same effect as wiring the red wire to the black terminal and the black wire to the red terminal. Yeah LMS/processor/active crossover ect.

The effect is the driver moves in the opposite direction when the signal is positive compared to a driver wired red to red black to black.

This is done (but not always needed) when the bins are loaded with backwards firing drivers, such as the HD or USB.

Adding to yoru previous question about reflex bins, they dont have long horn paths that affect the delay compared to big horns like labs ect.

Horns have other phenomena like natural high pass filtering and all kinds of other things. Their usable pass band is also more limited compared to reflex, typically. This means more complex systems with more crossover points, more places to be out of phase or time.




Posted By: sushi
Date Posted: 20 September 2019 at 2:47pm
Hi, and thank you for the explanation.
I did clear up by myself my phase/polarity doubt: they are kinda same thing (well they are not, but they are consecuential, as inverting the polarity does actually invert the phase). Really felt stupid for not getting it at the first moment.
Some days ago, a soundtech i work with told me an easy way to set this kind of delay without much math: using a sinusoidal wave just with the frequency you would cross the smt's and the subs at, invert the phase of subs (by inverting polarity or simply from the active crossovers "switch phase" buttons), start delaying the subs more and more, when the signals from the two speakers match they cancel the sound and that will be the correct delay to set. then you can reverse the sub phase again.
I know it's a basic trick for most PA men, but i'm starting to learn now and i didn't ever heard it until a week ago.
About the need to set a delay between the midrange and the HF driver.. i seem to be very lucky, 'cause the horns i'm gonna use for the SMT are long enough to put the driver in an alligned position with the mid woofer, so i think i will not bi-amp them, just put a passive crossover inside the box (obviously in the HF driver chamber, as the woofer chamber is already too small and need to be dampen).
STILL i didn't start building the cabs, just purchased the wood..


Posted By: toastyghost
Date Posted: 20 September 2019 at 4:31pm
At the expense of confusing you again, I’m afraid your statement at the start is not correct. Inverting polarity swaps the positive and negative of a signal, inverting the waveform. It does not apply any delay or alter the time element of the original signal, so it is only affecting phase in a relative manner to the original signal.

This may make you ‘out of phase’ with another signal, causing ‘phase cancellation’ but it is not a phase inversion. You can’t actually ‘flip’, ‘invert’ or ‘reverse’ phase, you can only shift it via various means.

It is also not the same thing as applying enough delay to get a 180 degree rotation at a given frequency.

Sorry if that makes it more difficult but its a very common misunderstanding and a very important one to distinguish the differences between.

Try to think of phase shift moving the waveform ‘left and right’ and the polarity flip turning it ‘upside down’


Posted By: sushi
Date Posted: 21 September 2019 at 5:10am
Originally posted by toastyghost toastyghost wrote:

At the expense of confusing you again, I’m afraid your statement at the start is not correct. Inverting polarity swaps the positive and negative of a signal, inverting the waveform. It does not apply any delay or alter the time element of the original signal, so it is only affecting phase in a relative manner to the original signal

Well i didn't say that inverting polarity gives any delay.. i understood that reversing polarity causes the speaker cone to move reverse (back and forth instead of forth and back) and the phase to be reversed "upside down".
What you say is "switch phase" buttons on an active xover doesn't have the same effect of an actual polarity reverse on the speaker wiring, isn't it?
The confusing thing seems to be for me your last sentence: if phase switch just moves the phase left and right that seems to be a delay! (i know it is not )


Posted By: toastyghost
Date Posted: 21 September 2019 at 8:02am
It is not a ‘phase switch’. It’s a ‘polarity invert’ switch. It is exactly the same as swapping the positive and negative wires in the cable or at the speaker connection.


Posted By: sushi
Date Posted: 22 September 2019 at 12:27pm
Yeah, I checked in my crossover manual as well.. "invert" switches actually reverse the polarity of the single outputs.


Posted By: sushi
Date Posted: 06 October 2019 at 12:54pm
Hi everyone, i finally built my pair of single 12" SMTs. Still have to cut the holes for handles and connectors plate, which i'm going to do next week together with a good puttying and sanding job.. here are some pictures, as promised.
Cheers


Posted By: Fracture_clinic
Date Posted: 06 October 2019 at 8:21pm
Crackin build mate! Keen to see more progress


Posted By: sushi
Date Posted: 10 October 2019 at 9:42pm
During this last days i've cut the holes for handles and connector plates, done a puttying/sanding job, and painted the cabs with a wood impregnating agent.. soon i'm going to paint them with black poliurethanic paint (water based).
Here we are with some new pictures


Posted By: Robbo
Date Posted: 10 October 2019 at 10:10pm
Don't forget to fit the supports inside behind the horn flare cut out to give the HF driver support before you go any further in case you need to drill any screw holes before final finishing.


Posted By: sushi
Date Posted: 11 October 2019 at 10:33am
Hi! Thank you for you advice! i already kept some wood to make those supports, i'm gonna try and put the driver and the horn inside and place the supports in the right point through the handle holes. Plus i modified both the aluminium horns i already had, by making 4 new screw-holes in the central section (they only had 4 holes, all on the sides).
I'm not gonna glue or shot nails in the supports, just put some screws because i want them to be removable: probably next year i will buy a new pair of hf drivers and they might be bigger or smaller.. theese drivers i have are good and loud but they are my spare ones, plus i don't even know brand or model, nothing's written on them!
Well i'm posting a picture, maybe i'm lucky and some of you recognise the model..
They totally look like B&C D3 model but they are slighly different.. maybe a clone?


Posted By: rosssss224
Date Posted: 11 October 2019 at 12:05pm
Brillaint work! How do you get the LF in/out? Can I just not see the access panel?


Posted By: sushi
Date Posted: 11 October 2019 at 12:42pm
There's no access panel but the round cutout. It's a front loaded cab, if the size of panel A (in project) is correct, 12" woofer fits perfectly.


Posted By: sushi
Date Posted: 08 November 2019 at 12:16pm
Hello everyone! I finished my pair of SMT112, and as promised i'm posting some pics.

I loaded them with Eighteensound 12ND610 and my spare hf drivers, placed passive crossover (filter at 2900hz) inside hf chamber, dampen lf chamber.. i tested them indoor (not at full power) and i really liked the sound, clear highs, punchy and loud mids, gets even lower than i thought.. not a kick bin however, so i'm gonna use them from 200hz more or less with hd15 under them. really looking forward to the next gig (30/11 in Milan, IT) to make them shout properly.
Oh, i tested them with Kappa12A as well: not bad i have to say.. but the 610 blows it away, even on lower frequencies.
I'm quite satisfied with this build, hope to see more progress and pics from FractureClinic, your 3way SMT project was dope mate.
Cheers everyone!


Posted By: Jeferica
Date Posted: 19 January 2020 at 1:28pm
hello. I saw a video with a smt with the high horn im the middle of the cab (just lile im the MT horns) does anyone how this project name or how i can modify a smt im that way? i will just cut the rear chamber in half, separating the 2 woofers? 


Posted By: Fracture_clinic
Date Posted: 19 January 2020 at 8:04pm
Originally posted by Jeferica Jeferica wrote:

hello. I saw a video with a smt with the high horn im the middle of the cab (just lile im the MT horns) does anyone how this project name or how i can modify a smt im that way? i will just cut the rear chamber in half, separating the 2 woofers? 


I could probably take a wack at drawing up a plan for a design like that over the next week or so.


Posted By: sushi
Date Posted: 20 January 2020 at 11:12am
Hi
It seems to me the design is quite different from the SMT for theese reasons:
1) The woofers looks like 15" (not 12") and its evident when you look at the distance between the speaker itself and the edge of the cab, in original plan 12" woofers are placed way deeper in the cab.
2) Reflex ports are not seen, they could be the 2 rectangular spaces on sides of the hf horn, but in this case it's clear they have different area from the original triangular ports for the 12"woofer.
Honestly i think this cab's project is not a variation of the SMT, but a different project, that you may even find on the internet. Adapting SMT project to a double 15", also with the horn in the middle, would cost you more time than searching for already existing plans for this design.



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