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Variation of SMT-212

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toastyghost View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post 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’

Edited by toastyghost - 20 September 2019 at 4:32pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sushi Quote  Post ReplyReply Direct Link To This Post 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 )

Edited by sushi - 21 September 2019 at 5:15am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post 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.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sushi Quote  Post ReplyReply Direct Link To This Post 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.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sushi Quote  Post ReplyReply Direct Link To This Post 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


Edited by sushi - 06 October 2019 at 12:56pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fracture_clinic Quote  Post ReplyReply Direct Link To This Post Posted: 06 October 2019 at 8:21pm
Crackin build mate! Keen to see more progress
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sushi Quote  Post ReplyReply Direct Link To This Post 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

Edited by sushi - 10 October 2019 at 9:49pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Robbo Quote  Post ReplyReply Direct Link To This Post 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.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sushi Quote  Post ReplyReply Direct Link To This Post 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?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rosssss224 Quote  Post ReplyReply Direct Link To This Post 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?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sushi Quote  Post ReplyReply Direct Link To This Post 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.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sushi Quote  Post ReplyReply Direct Link To This Post 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!
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