Re-designing speakers

hi captrajesh -

perhaps, not a good idea to use multiple screws - perhaps a single bolts from top to bottom (as seen in the second magico mini photo) - just fevicol held under pressure until dry will give a good build - but in the tropics, fevicol and mdf expand during the humid season - and you might see minute cracks on the exterior - and that will mar a flawless finish.

better to run, say, three bolts through and through - and tighten at either end with nuts which are recessed into the MDF - with fevicol applied sparsely between the individual boards - allow three days to dry before further work on it

all the internal can be accessed through the woofer opening - and a removable top may not be necessary ( i like the arrangement because i do not like removing the woofer once it is mounted - and when the cross-over needs a part to be changed. or the wiring has to be replaced - prefer to lift the lid!)

if the sidewalls are going to be only one inch thick - then braces (as you have suggested) will become necessary

the costs-

two 8' x 4' MDF boards = 2900 rupees (1450x2)
fevicol half-kg = 180 rupees (?)
three stainless steel bolts threaded at both ends (11") = 360 rupees
N.C. lacquer, sanding sealer, sandpaper, black stainer = 1100 rupees

add to this cost of labour of carpenter and cost of labour of polisher (who might hire a compressor at 500 rupees per day for spray application of lacquer- it will take 4 days to apply the necessary coats.

regds suri
 
Hi Rajesh,
Where you purchased fabric cone tweeter from ritche street and what is the price? Please PM me. I am planning to purchase that.

Thanks in advance

Vijay
 
Before you go for a new extensive (and expensive) box,
make a test box and try as per my post #7. If somehow you could use a 4-5" PVC pipe instead of making atest then it could be very cheap and sufficient.

If you like the sound, proceed with the fabulous extensive box as per your original plan.
If not let the drivers be in their original box.


Hope this helps.
Goldy
 
i am personally of the opinion that its not a good idea to make such a kick ass cabinet for drivers of disputable quality. Later if you dont like the sound, you can chuck the drivers, but will you feel like chucking the cab in which a lot of effort and money has gone in. It might be a better idea to build a simple cab with 3/4" thickness and see if you like it before sinking a lot of money into it. Later when you have learned things from this experiment and are ready to make good speakers with good drivers, you can use a cab like that.

+1 :)
 

but -

why create another mediocre cabinet?

it will sound the same - ?

with 3/4 inch sheets of MDF - one cannot create curved sides -

with such (flat) boards of MDF - one is doing nothing - except replacing "chik-board" with MDF.

that method creates a resonant cabinet - with much the same characteristics as the existing cabinet (though, -that is particle board -)

so - why should captrajesh create another (equally) inferior cabinet -

and hope to be pleased with the sound?

doors666 and grubyhalo - examine your thoughts and post again.
 
Oh no, my line of thinking was to make a fabulous 'out there' design for the cab and use a superior speaker design, especially if he's intending to go the 'trans-lam' or 'trans-MDF'(?) route. I just wouldn't want too much of effort being pumped into a speaker design that 'might' let the cabinet design down... :)
 
Just catching up with the posts.

@goldyrathore, doors666 & grubyhalo; The existing cabinets are made of 10 mm MDF and have pretty decent sound quality but for the vibration sound at loud volumes when playing bass heavy content. This is due to the vibration of plastic baffle which is fixed on to the cabinet with four screws rather than the drivers.

So as Suri opined, I do not know what additional information would I get by testing in PVC pipes etc.

My intentions of re-designing the speaker cabinets are: -

1. Somehow I got drawn into this DIY business; I'm finding it to be a nice hobby.

2. To use better quality tweeter and cabinet and see the quantum of improvement of the SQ.

3. Make the speaker front ported to enable their placement close to the wall if not directly fixing on the wall.
 

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Make sure you close that box shut before the birds nest in there. Dont leave it hanging around and open ... Else you will hear multiple "tweeters" a few months down the line and wonder what happened to the SQ :)

Cheers
 
but -

why create another mediocre cabinet?

it will sound the same - ?

with 3/4 inch sheets of MDF - one cannot create curved sides -

with such (flat) boards of MDF - one is doing nothing - except replacing "chik-board" with MDF.

that method creates a resonant cabinet - with much the same characteristics as the existing cabinet (though, -that is particle board -)

so - why should captrajesh create another (equally) inferior cabinet -

and hope to be pleased with the sound?

doors666 and grubyhalo - examine your thoughts and post again.

a 3/4" mdf cab with double baffle and some bracing will not create a mediocre cabinet. it will be far superior to the 10mm cab that is currently in use. The stacked design for cabs is better but also deserves better drivers. If the drivers are not good enough, no amount of cabinet work will make a great speaker. Once the cab is ready and the speakers dont sound great, what to do then, you cant just drop in a new driver in there.

Maybe its a good idea to calculate the t/s parameter and see the response in software. that will give some idea of the quality of the drivers. Maybe it will show that the drivers are not good enough to go ahead with the expensive cabs or the project itself.
 
Goldyrathore was kind enough to send me a link to download the required software & way of calculating it but I'm not sure of what exactly are deduced from these parameters.
Can anyone throw some light for the noob that I am?
 
Maybe its a good idea to calculate the t/s parameter and see the response in software. that will give some idea of the quality of the drivers.

hi doors666 -

unless captrajesh has the (quoted) parameters of those drivers......

it will be very difficult for him to work up a test rig to get those parameters-

Measuring Loudspeaker Driver Parameters

i look at it this way -

captrajesh has identified a DIY project that he wants to do without involving himself (too much) with technicalities and specifics-

captrajesh will (perhaps) want to make something that will warm his heart each time he looks at it - perhaps, run a hand over the black piano gloss finish and shed a tear over the magic(o) he has created! - certainly, it will be a conversation piece- and when captrajesh has his (golfing) friends over, those superb visual cues will add more depth to the "oohs" and "aahs" of appreciation, even before the music is played!

and captrajesh can add fail-safe this way - look up proven designs on the www - with same driver dimensions - and similar external front baffle and driver arrangement - and similar (approx) internal volumes- i have seen some scanspeak designs - and i think a sonus faber (clone) design is available -
with almost the same dimensions as captrajesh's speakers (and the magico mini shape)- anyways captrajesh wants to use leather on the front baffle..

regds suri
 
a 3/4" mdf cab with double baffle and some bracing will not create a mediocre cabinet. it will be far superior to the 10mm cab that is currently in use. The stacked design for cabs is better but also deserves better drivers. If the drivers are not good enough, no amount of cabinet work will make a great speaker. Once the cab is ready and the speakers dont sound great, what to do then, you cant just drop in a new driver in there.

Maybe its a good idea to calculate the t/s parameter and see the response in software. that will give some idea of the quality of the drivers. Maybe it will show that the drivers are not good enough to go ahead with the expensive cabs or the project itself.

I agree 100%. I was about to post on exactly the same lines yesterday but then decided against it because I didn't want to discourage the Cap'n from going ahead.
Cap'n, if you are inclined to build a new curved cabinet using the existing mid-woofer with bracing et al, I suggest that expectations be toned down.
OTOH, maybe the sound will improve radically. Stranger things have happened :lol:
 
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I agree with GoldyRathore, doors666 & keith_correa - Measuring TS parameters and simulating in a software like Winisd is a proven and scientific method for getting best results for any driver. Driver behavior complies with the laws of Physics and software simulations are close to real-life scenarios.

Suri,
Software like Limp (which is a part of Arta) makes it very easy to measure the TS parameters by using the computer's sound card. No complicated jig as mentioned by Rod Elliot is required - All that's need are two stereo jacks, 3 wires, a 100ohm resistor and few 5 rupee coins. Checkout this link for more details. The demo version of Arta allows TS measurements.

Captain,
You can fabricate a measurement setup easily by buying a cable with two stereo jacks, cut it in half and wire as indicated in the above link. In case you don't have a soldering iron, a radio shop technician will be able to do it in 5mins.

Regds...
 
@Keith & Doors
Fauj mei jane ke baad dimag ghutne mei utar gaya. :lol:
Jokes apart, rather than going through voluminous data & losing enthusiasm in the process, I thought of getting ready-made info on what to make of the data. The speakers came out of a european diplomat's home & sound pretty decent.
 
T.anthony
Ur msg came while I was typing my previous msg through my mob which is a clumsy affair. Tk u for the info; I got it from Goldyrathore. My query is, what aspects of speaker design are determined by the TS parameters
 
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