2-Way DIY Project INDIA

[Hornswoggle]

After months of reading posts I have begin to build my own 2-way standmounting speakers. The drivers used are Peerless India 1" silk dome LR10DT and 6.5" JVC CTC-J500. I have measured the open-air impedance and hence used it to calculate various values using WinISD Pro Alpha.
I am hoping members here will guide me through an adequate second order Linkwitz-Riley crossover network or any other method, also on whether it should be a closed or a vented box. BTW I am an electrical engineering student so I do understand technical terms well.
The calculated measurements of drivers are,

Peerless LR10DT --
1 inch silk dome 8 ohm
Qts=1.944
Vas=0.015
Fs=1350Hz
Re=6.6 ohm
Z=10 ohm
Qms= 3.4
Qes= 4.540
SPL= 84.61dB
Bl= 1.82466 N/A
Dd= 2.93 cm
Sd= 6.8 sq.cm

JVC CTC-j500 6 ohms
6.5" hard cone(for lack of a technical term i don't know)
Qts= 0.519
Vas= 37.31 litres
Fs= 47 Hz
Re= 4.456 ohm
Z= 6 ohm
Qms= 2.858
Qes= 0.635
SPL= 0.853 dB
Bl= 4.60320 N/A
Dd= 12.91cm
Sd= 131 sq.cm

My aim here is to get a bass response adequately deep and smooth peaks from the tweeter. But I find designing the box difficult since the Qts offered buy the woofer is around 5.2 which is a bit more than 0.5 and not that high to completely support a vented enclosure. Also I don't know how to design and use internal bracing.

I would be thankful for any inputs. Thanks !

[Hornswoggle]

Oh sorry, the corrected SPL values are 86dB for woofer and 89dB for the tweeter. Hoping for some replies.

[Hornswoggle]

Now the tweeter will give best result when given a rear port enclosure
But the woofer shows a large volume of 70 liters when enclosed in a rear-port enclosure having vent length of about 12-15cm with port diameter being about 7cms.

Ported enclosure will give enhanced low frequencies than a closed enclosure. I need some suggestions on how to bring the vented enclosure's volume down.
I use speaker-calculator at mhsoft.nl and WindISD pro alpha.

[sreten]

http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.geocities.com/woove99/Spk...esigningXO.htm

http://www.zaphaudio.com/
http://www.rjbaudio.com/projects.html
http://www.troelsgravesen.dk/Diy_Lou...r_Projects.htm
http://www.humblehomemadehifi.com/
http://htguide.com/forum/forumdisplay.php4?f=39

http://www.linkwitzlab.com/
http://www.geocities.com/kreskovs/John1.html


Hi,

Speaker calculators are simply wrong ......

You cannot rear port a tweeter. Its Qts of 1.9 indicates it
is very tricky to work with. You need a frequency response
and a impedance curve to to do the job properly.

FR ands Z curves are also needed for the bass / mid.

Boxes bigger than Vas are a bad idea, so it must be sealed.

I'd say it was designed for HT use (i.e. intended to be used with
a small setting, 80Hz highpass filter). Box size is say well stuffed
12L (~ 15L effective) Q = ~ 1 up to 18L (~ 24L eff), Q= ~ 0.8.

For the classic Q= 0.7 you need a well stuffed 36L box, too big IMO.

/sreten.

[Hornswoggle]

Hi sreten, thanks for replying.And thanks for those educative links, here in India one can't get superb drivers, but one can access internet well. So no complaints!

Also by THE ASAWARI's creator, TCPIP, the drivers matter only 10% of the o/p, 40% to the enclosure and 50% to crossover network. So going by that I need to concentrate more on enclosure and crossover.

The free-air impedance of the tweeter is 1350Hz and for the woofer is 47Hz. This is to the best of my knowledge.I am yet to measure Vas.

When I simulated the response for the tweeter in using WinISD Pro Alpha, it gave a vented enclosure at 3.86L with Impedance of 11.5 ohms, the FR was bizarre with two peaks, first lower than the second at Fb =269Hz. SPL was maximum at 91.56dB with a peak at 1400Hz and dropped at 88db through 40dB/decade(12dB/octave). The alignment was Chebyshev.

I need suggestions with tweeter enclosure.

WinISD shows a box of 34L for a Qtc of 0.511 and Fsc of 65.12Hz. I am sure to follow your advise on sealed enclosure for the woofer,sreten.

Also how does the "mass added to cone" affect FR, Phase response? The added mass to cone on specification sheet is 15gm, when added to simulated graphs almost affects every response.
Thanks in advance.

[Hornswoggle]

Would anyone please reply ?

[navin]

Originally posted by Hornswoggle
After months of reading posts I have begin to build my own 2-way standmounting speakers. The drivers used are Peerless India 1" silk dome LR10DT and 6.5" JVC CTC-J500.
Peerless LR10DT --
Fs=1350Hz
SPL= 84.61dB
JVC CTC-j500 6 ohms
Qts= 0.519
Vas= 37.31 litres
Fs= 47 Hz
SPL= 0.853 dB
My aim here is to get a bass response adequately deep

Originally posted by sreten
You cannot rear port a tweeter. Its Qts of 1.9 indicates it
is very tricky to work with....
I'd say it was designed for HT use
18L (~ 24L eff), Q= ~ 0.8.

Originally posted by Hornswoggle
I need suggestions with tweeter enclosure.
WinISD shows a box of 34L for a Qtc of 0.511
Also how does the "mass added to cone" affect FR [/B]

The drivers you got are nice try this for starteers.
1. Build 18-20 liter (net volume) sealed box (Vas/2)
2. XO at 3khz 12db remember to add baffle step compensation (simply a L-R combo in series with the woofer) and pad the tweeter down about 3-4db.
3. You might need some impedance compensation for the tweeter but for now leave that. without freq resp and impedance curves we cant get any real numbers anyway.
4. Dont expect this woofer to produce much below 70Hz. It was not designed for that.
5. dont add mass to the cone. It might push F3 down a bit but will affect Bl/Mms ratio and that will reduce sensitivty further (the woofer after baffle step is about 82db/1W). Also I am not sure if the suspension (spider) of the woofer will be capable of managing this extra mass over an extended period of time.

[sreten]

Hi,

1" dome tweeters are sealed and do not need an enclosure.
simulating tweeters in WinISDPro ? only thing simmable is excursion.
The tweeters parameters include the sealed loading or should do.

Also by THE ASAWARI's creator, TCPIP, the drivers matter only 10%
of the o/p, 40% to the enclosure and 50% to crossover network.

Yeah right ..... if you think this means the drivers do not matter
you are completely wrong, you are stuck with them, and if they
are not up to much the box and crossover cannot "fix" them.

Added mass to cone ? probably simply effective cone mass.

/sreten.

[Hornswoggle]

Hi Navin, thanks for replying. The crossover freq you've mentioned is 3KHz, is it a bit too high ? I've read a post by you mentioning that for a two-way system, the XO should be around 1.8-2.2KHz. I am sure you must have had strong reasons to suggest so. Also could you please tell me more about the Impedance compensation required for the tweeter.

Is 82dB/1W sensitivity too low for the woofer ?

Thanks in advance.

[Hornswoggle]

Thanks for replying again Sreten.

Yeah I was mistaken by simulating tweeter in WinISD Pro. So as I am picturing it, the tweeter will just be fixed over the Baffle and below would be the woofer.

What kind of Internal bracing does the enclosure need ? The woofer, as you said has to have very heavy damping. But, please excuse my moronity, and tell me if a sealed tweeter will need any damping at all ? I don't think it does.

I just need to opinions on internal bracing. DIYs like Roman Bednarek, John Krutke and many others have used internal bracing profusely in their standmount speaker projects.

Yes the drivers do constitute a very important part of speakers since they are the actual transducers used for sound reproduction. But here in India, good drivers are sold sporadically, hence I have to do best with what I have.

Thanks in advance.