My Drivers..i Finally got them!

Hey Manek,
The gasket(bought from Corrson) only helped in reducing the rattling but not eliminate it completely.

Neutral, the thing is, MDF is plain sawdust compressed and once a screw is put into it and removed and put in again , the bonding at the second instance is very much compromised and this should be the reason contributing to the rattling sound.

I guess, i'll have to drill new holes, then screw it on with nuts and washers so that the joint is perfect and does'nt budge.
But am pretty happy with the bass response from the speakers, barring the above mentioned glitch. However, I need to try to measure the exact frequency that the box is tuned to so that i can evaluate how much of a compromise my enclosure is, when compared to the actual T/S parameters
Cheers,
Benkenobi

benks hope you are using t-nuts to mount the drivers....

Hey Manek,
nope. Am not using T-nuts.
I wish i could land my hands on them....have'nt been able to find them here. I guess i need to look harder for them...
Do let me know if you can get them for me or assit me in that regard..
Cheers,
Benkenobi

Dear Sachi,

For your T Nuts, you may want to try

India Techtran Electronics
(India) Pte Ltd.
5/3, Ballygunge Place
Unit # GB
Kolkata - 700 019
India

techtran4@vsnl.com
techtranho@sify.com
Phone
91-33-24607030
Fax
91-33-24607031

They have got a Bangalore representative

Regards,

Junia.

Thanks for that Junia.

Btw, did a bit of testing today and fired up all three drivers using two channels of my NAD and one from the yamaha.

Honestly, It did not sound that good. I think the Mid needs to be xovered a bit higher.
Maybe 500 Hz ought to do the trick. Presently its Xovered at 350Hz..

the highs too could be xovered a bit higher..
maybe 4.5-5 KHz.

The mids are sweet but seem overpoweing the highs...and i don't seem to be able to reduce the gain for the mids without a scope.
Also, there seems to be a fair amount of extraneous noise(that hisss noise) when there is no music from the tweeter.

The bass too is a bit, just a bit loose, maybe even thin.
Lots to do with no time to do it in...
Cheers,
Sachi

The fun is just starting.....
Voicing………….man that is where the head-ache is…………………….. Measuring and all that is fine…………..now it needs to pass the biggest test of all with the most sensitive instrument of all…….u’r ears.

benks I remember that siva had t-nuts...you could contact him....check for integrity of the cabinet/baffle...maybe the braces inside resonating ? you may need to strengthen your baffle joint with some L-braces inside. Delrin is quite a inert material and you do get a delrin right angles.

But T-nuts are in order, if not then put a threaded flat metal plate inside to each screw to act as a checknut. Dont rely on the threads made into the MDF plank.

Manek.

Dear Benks,

If the bass is loose it is fine, better to be loose than boomy....which means your box has got excess volume

The T/S parameters have to be measured in free Air & in the box & they you would have to decrease the volume inside your box.

Vance mentioned the same in his book....details are mentioned...I think in the last chapter.

If you go to the Cross Over Section, in Vance's book, could you advise, what the separation frequency between the woofer to midrange & midrange to tweeter need to be ? Also mention was made of avoiding crossover at certain frequencies have you taken care of that ?

After that you need to go by ear on a trial & error basis till you reach Nirvana !!

The beauty of an active system is you can regulate the output level of each section. A good way is to generate a tone of the exact frequency crossover point & make sure that the Woofer & Midrange sound equal to you in output, similarly for the midrange to tweeter crossover. Or you could do it by White noise..or FM hiss as to equal outputs.

Blue Tac should help you out as to prevent rattling. Alternatively Sika® Elastosil®-605, Sikaflex®-20 AT or Sikaflex®-Construction would do the trick...if you need some do let me know I can bring some over for you.

Regards,

Junia.

Hey Junia,
Yeah taht's what i thought too. I remeber talking to you about this the other day. Guess will have to wait for you to come over. Thanks also for the blue tac offer. I'll PM you regarding this.
As far as i know, in electronics(Wavelet Transforms), we learnt that the two most important critical frequencies are 500Hz and 3.5khz(The higher freq am not too sure, but it is pretty much somewhere there).
But this is critical frequencies while recording and i doubt if it has any significance in speaker building.
Regarding the xover frequencies,i'll check out the books and let you know. Am already swamped trying to read 3 books at the same time while studying for GRE .
Cheers,
Sachi

Dear sachu,
better not to select the crossover freq above 300Hz since as it goes above that ur ear will definitely identify the change. But one more mistake in ur design... when u gave the signal input then what u said is that exactly at the crossover points you are not at all getting sound.... This means that there is a serious dip in the transition of frequencies. Ive forgotten to tell this...

what you have to get is that you must get equal intensities from the both the drivers( the drivers which you have crossed ) at that point you need to get the resultant intensity flat. I mean same as the single driver. Just check it out... You can do this by using some simulation softwares... the only thing I suggest at this moment is that just check the crossover freqs and think over the dip.

cheers,
Sandeep

Guys, don't want to jump the gun here...but the speakers sound damn good when i play Trance and bass numbers..
i don't know if you will believe me..but the main door which is 1 inch thick and is 24 feet away is shaking like mad...
and that too all from just one channel(opnly mid and woofer sections or one cabinet were connected)!!!
but in other forms of music, like direstraits and stuff.the highs nad mids are good but the bass is not right.sometimes loose..
lots to tweak and measure..
But for trance...man! these babies are like a coupleof 10 inch subs!!

I have them running on my Nad amp presently...but once i get the amp done and with 120 watts pumping each of these brutes should be more fun.

Isnt there a Listening test in TOEFL ?.... IN case you are taking that, you may want to lay low on that fun part for some time

hehhe....
am done with TOEFL..
just GRE to go!...am just waiting for it to be over..

Dear All,

Recently i have come across some infomation on the web(read diyaudio.com) that Plywood is much better than MDF.
An additional piece of information is that my bracing is not proper.
It seems the bracing needs to be oblique in nature.The shelf type unobliquity doesn't make much of an effect.
Hopefully i will be able to make some changes to the cabinet..or build a new one after i am done with this(read 'complete experimentation')
One more thing. The the bracing needs to be coupled to the driver magnet and if the panels are rounded off then they are supposed to be naturally braced.
This is what i gather from some postings by diyaudio.com moderator planet10 on one of his unusually long posts.

Cheers,
Benkenobi

benks...did'nt quite understand it....could you clarify
"The the bracing needs to be coupled to the driver magnet and if the panels are rounded off then they are supposed to be naturally braced."


tks

Manek.

coupling the driver magnet to the bracing and the cabinet means like having a H brace which will fit snugly against the magnet while simultaneously coupling the brace(obviously since the brace would be attached to the cabinet) to the cabinet.

am not entirely sure of what they mean by rounding off of panels. but as i understand it is the rounding off of the inner corners of the cabinet. in fact nowadays you get specialised pieces which can be fit into the corners of the cabinet to give the required curved finish. They come in different sizes depending on the size of the cabinet.

Benkenobi

benkenobi schrieb:

coupling the driver magnet to the bracing and the cabinet means like having a H brace which will fit snugly against the magnet while simultaneously coupling the brace(obviously since the brace would be attached to the cabinet) to the cabinet. am not entirely sure of what they mean by rounding off of panels. but as i understand it is the rounding off of the inner corners of the cabinet. in fact nowadays you get specialised pieces which can be fit into the corners of the cabinet to give the required curved finish. They come in different sizes depending on the size of the cabinet. Benkenobi

Hi Ben,
Firstly why use wood?Think alternatively . I am sure a creative chap like you will come up with options.Tell you a secret, try paper .
Regards Deaf

[quote]Hi Ben,
Firstly why use wood?Think alternatively . I am sure a creative chap like you will come up with options.Tell you a secret, try paper .
Regards Deaf[/quote]

am not sure what you are trying to imply. You seem to sound condescending...could you clarify your post?

Dear Ben,
I am very serious,get rid of the wooden cabinet thought process.Put a pen to paper and think out of a box.You have the advantage of being active, use it to its full potential.I'll give a hint, you were surprised that a subwoofer of this type has been attempted in India. .Think hard OUT OF THE BOX, do your calculations again, and the answer is right in front of you. .Best of luck.
Regards Deaf.

WEll yeah..i mean if i had the money i would have gone in for a dipole or even a push-push bipole...my speaker building is for now determined by how much leeway my parents are willing to give.
But i am pretty pleased with the progress so far.
In fact, gave a very brief demo to Edges the other day. had connected only the mids and the lows of one channel(left)...he was pretty impressed...the thing is like a subwoofer. can't wait to see what the two(left and right channels)can do together. ..even the def tech doesn't play this loud(it goes deeper though)!!.

Dear Ben
I wish it were possible to see your project.I may have been of some assistance regarding enclosure thought process.Do feel free to ask for any input if you feel like.
Regards Deaf

well...if u try a bit harder u might..
nway..let me make it easy for u..
here u go..
http://hifi-forum.ne...ack=1&sort=lpost&z=9
scroll down and u should see he pictures.

Hi Ben
Looks nice.In fact you don't need to do much,just add 3 vetical braces identical to the horizontal ones,but sitting on the central part of the horizontal brace 1 to top of enclosure, horizontal brace 1 to horizontal brace 2,brace 2 to bottom of the enclosure.Take hollow aluminium channels 1"x1", fill with high density dry sand, and attach to cabinet sides at 1/4 and 3/4 depth from front baffle.Between the wood and aluminium, so as to ensure perfect contact use very thin rubber sheets, full lenght of the channel, and then screw onto the wood.Hope it helps.
Regards Deaf

deaf schrieb:

Take hollow aluminium channels 1"x1", fill with high density dry sand, and attach to cabinet sides at 1/4 and 3/4 depth from front baffle.Between the wood and aluminium, so as to ensure perfect contact use very thin rubber sheets, full lenght of the channel, and then screw onto the wood.

did not follow u there..the aluminium cylinders are to be inside the enclosure..?
what's their purpose...?

benkenobi schrieb:

deaf schrieb: Take hollow aluminium channels 1"x1", fill with high density dry sand, and attach to cabinet sides at 1/4 and 3/4 depth from front baffle.Between the wood and aluminium, so as to ensure perfect contact use very thin rubber sheets, full lenght of the channel, and then screw onto the wood. did not follow u there..the aluminium cylinders are to be inside the enclosure..? what's their purpose...?

Dear Ben
Not cylinders, rectangular channels,vertically screwed from top to bottom inside the cabinet, at 1/4 and 3/4 of the total internal depth.Do not forget the 1.5" wide(not thick) rubber lining that will act as a gasket between the channels and the cabinet wood.Make sure that the channel ends are sealed with a cap once you fill sand in it before you attach them to the inside of the enclosure.The purpose is to stiffen the enclosure thus take the resonating frequency higher.
Regards Deaf

Dear deaf,
Thanks for that.
Hope to meet you soon.
Cheers,
Benkenobi

Dear Ben
The pleasure is mine.Really look forward to meeting you and hearing your project.
Regards Deaf

Hey guys,
just received my shipment from Analog Devices..
Damn nice chaps to have sent me 6 of their AD713 Opamp chips..
total cost on the market of these babies is 50$.
Can't wait to test them out. am expecting a pretty substantial improvement over the TLo74s that are presently in the active xover.
Benkenobi

benkenobi schrieb:

Hey guys, just received my shipment from Analog Devices.. Damn nice chaps to have sent me 6 of their AD713 Opamp chips.. total cost on the market of these babies is 50$. Can't wait to test them out. am expecting a pretty substantial improvement over the TLo74s that are presently in the active xover. Benkenobi

Dear Ben
What x-over slopes are you using for your project?
Deaf

24 dB per octave..Linkwitz Riley arrangement..
this is the xover that i am using. i got the PCB made and did the populating.total cost of the oxver including the power supply(transformer),PCB is around 600 bucks..now, the 6 new chips alone cost 2400 rupees.of course, i got them for free.
http://www.siliconchip.com.au/cms/A_30278/article.html

benkenobi schrieb:

24 dB per octave..Linkwitz Riley arrangement.. this is the xover that i am using. i got the PCB made and did the populating.total cost of the oxver including the power supply(transformer),PCB is around 600 bucks..now, the 6 new chips alone cost 2400 rupees.of course, i got them for free. http://www.siliconchip.com.au/cms/A_30278/article.html

Dear Ben
That is the best choice if your baffle is flat,which in your case it is.However since you are using LR 24 it would be best to spread the two x-over points as far as 4 octaves to minimise
errors in the summed response.
Regards Deaf.

present xover points are 350 and 3.4kHz.....so no problem there..

Dear Ben
Seems alright, but try 200Hz and 3.4kHz if possible via the active x-over.Btw how wide is yourv enclosure?
Regards Deaf.

The Fs of the midrange is 110Hz...and the rule or guideline is to keep the xover freq at least 2 and a half octaves greater than the Fs.This basically depends on the type of box the speaker is placed in and the sope of the xover. am sure..u know this. hence for now i have kept it at 350 Hz.
Of course, i will revise this if the results are not satisfactory.

The dimensions of the woofer cabinet are:
Height-32.5(internal 31)
Width-13(internal 11.5)
Depth-14.75(internal 13)
diemnsions of the mid and tweeter cabinet(sealed)..
height-13 inches(internal 11.5)
width-6.5 inches(internal 5)
depth- internal tapering from 3 inches at the top to 4.5 inches at the bottom(from tweeter to mid).

Do u mean to use the width of the cabinet to determine the frequency at which baffle step occurs or is there another reason?

Benkenobi

Hi Ben,
I think the result might be almost similar with swapping those AD713 which is single version of AD711, Except for the small rise in the slew rate , I Suggest you can try with Analog OP467 or Texas TLE2144 , You might get good improvement with the chips mentioned. I recommend you try TLE2144, these can take +/- 22v so safely keep a margin and provide supply rails of +/- 18v,
These have quite good 14.5 v rails swing, low noise 10 nv/rt Hz (not really very low but quite acceptable).and a high enough slew rate 45V/Us,good O/P Current.
I hope this helps you a bit.

I think the crossover points are in proper limit for your mentioned drive units, Go Ahead.javascript:emoticon(' ')
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Regards

Arasu Kumar

Thanks for that Arasu...
can't wait for tuesday to come...will call to see if we can meet up then..Cheers,
Sachi

p.s did you find out about the Belden cables for the projector..? please do..as a reminder, i need 3 sets of 30 feet of Belden 1694A...

benkenobi schrieb:

The Fs of the midrange is 110Hz...and the rule or guideline is to keep the xover freq at least 2 and a half octaves greater than the Fs.This basically depends on the type of box the speaker is placed in and the sope of the xover. am sure..u know this. hence for now i have kept it at 350 Hz. Of course, i will revise this if the results are not satisfactory. The dimensions of the woofer cabinet are: Height-32.5(internal 31) Width-13(internal 11.5) Depth-14.75(internal 13) diemnsions of the mid and tweeter cabinet(sealed).. height-13 inches(internal 11.5) width-6.5 inches(internal 5) depth- internal tapering from 3 inches at the top to 4.5 inches at the bottom(from tweeter to mid). Do u mean to use the width of the cabinet to determine the frequency at which baffle step occurs or is there another reason? Benkenobi

Dear Ben the rule applies to first order x-overs, so that the driver is not over stressed.If you x-over at 225 Hz or so you will be -30db at Fs of driver electrically.Ofcourse putting the driver in an enclosure will take the Fb higher, I dont know what you mid enclosure Q is though,as that will determine your F3. You will have a greater rate of slope than 24db/octave as your enclosure will act as a filter too,plus a LR x-over will have the Q as 0.5, at x-over point, hence your driver will be down by 6db at chosen x-over frequency itself.
All this put together will ensure that your driver will never see distortion.The difficult part is that top end of your woofer should drop with the same acoustical slope as your mid,acoustical not electrical only.
Yes I did ask about the width for step baffle losses. Your enclosure as you know will act as a 4Pi below 350Hz(preciesly where your x-over is).Please do not try to compensate for the diffaction losses in a room below 3000 cubic feet as per the text book rules, because the room will add lift below 300 Hz if you are within 2'-2.5' of the rear wall.Adding the text book compensation will lift the bass, and along with room gain will give you a booming sound.
You may have to experiment with the gain keeping x-over of the drivers in mind to acheive a clean handover driver to driver.
Man this stuff is now giving me a headache, just trying to visualise you doing the math is making me ill .
Best of luck Ben, good talking to you.
Regards Deaf

Right guys the speakers are complete..
will be hauling them to Arasu's place tomorrow to hook the entire rig up...he's been more than helpful in my speaker building and helping me learn more aboiut audio...Kudos to him....
Will post pictures in half an hour.. .just one thing though...the carpenter made a boo boo at the fag end of the project..he accidently cut off past of the lamination sheet on the right channel...but the grill will cover it once that is ready.
Cheers,
Sachi

Okay guys..
as promised..these are the pictures of the finally finished speakers..
The xover is ready and u can see it on the floor in testing..

Have ordered for transforemers...if everything goes according to plan, i should have the setup ready by the first week of november.
The amplifiers need to be assembled and tested...
Hopefully today i will be taking the speakers and xover to Arasu's place to test them out with his amplifiers...will keep you guys posted ..


Pic1-Witht he grills on ...only need to paint or polish the grill and fix the cloth..



Pic2-with the grills off



Pic3-Just the DIY speakers



Pic4-Closeup for comparison with the diamonds



Pic5- The only disappointment was the scratch on the right channel..it can be clearly seen on the left edge..The amp is the NAD320BEE and the sub the Def Tech and the xover in test mode..



Cheers,
Benkenobi

May the Force be with You

Obi- wan,
Impressive.

K

Hi! Ben,
Great job! Sure has taken you a lot of time out of your studies to do this project. Did you keep a track of number of hours spent on this project. How does it sound in the end. I am sure many forum memberes will be interested in a listening session.

Havent you spiked the enclosures?

Keep up the DIY flag.
Rgds
Prithvi

Thanks Krish..

hey Prithvi,
Well i thought about it and i would have liked to spike the enclosures but i would need pretty big ones for it..
also, spikes would set me back by at least a grand...no money for it now...the amplifiers are the main concern..
Will let u guys know how it sounds after testing them out today..
Ur right Prithvi, it has surely taken a lot out of me...have spent a lot of time..lots more still to be spet in finishing up and refining..
It would have taken even longer or may not have even materialised if not for the infectious zeal of a few of my friends.

Benkenobi

Do spikes really help? I read a piece by Doug Blackburn that says that spikes don't matter much. Vibrations will anyway transmit. Building a better enclosure will be a more useful use of money.

And spikes scratch the floor I wouldn't dare use spikes on my marble tiles!

Ben.. how much does it weigh ?????

From the size , if you spike it, it might be coupled to the floor in a much much more stronger fashion than your parent would really approve.

They have more asthetic value than any sonic qualities. There would be a marginal improvememnt in the sound but there are other ways to solve this and get a better response cheaper.

benkenobi

Neutral schrieb:

Do spikes really help? I read a piece by Doug Blackburn that says that spikes don't matter much. Vibrations will anyway transmit. Building a better enclosure will be a more useful use of money. And spikes scratch the floor I wouldn't dare use spikes on my marble tiles!

Yes they do help..in most cases.

In the end it depends on what you want to achieve. it does tighten the bass for most speakers but it depends on the flooring

If you have carpets you NEED spikes else your speaker will not be stable.
If your speakers vibrate a lot with thin enclosures, you most probably need spikes to hold the speaker still.

On marble, if your speakers are heavy, what you might need more could be rubber bushings But if not and you have a bass reposnse not quite there, you could put a thick slab of Granite OR heavy wood and then put your spiked speakers on top..

Combinations are endless but in the end depends on your speaker AND your ROOM.. and experimentation is the key

LIke i said..i think that they are more for ASthetics than anything else..
unlseess u go for active speakers with the mid and tweeter cabinets seperated from the bass cabinet...then u could adjust the tilt and stuff...
But the sonic improvement for the amount spent is not justified..Theree are ways to achieve the same with very very little investment compared to spikes.

benkenobi schrieb:

Theree are ways to achieve the same with very very little investment compared to spikes.

Spikes can be really cheap..eg my stands came Free with them :).

Again You cannot dismiss them saying aesthetic value..they DO make a difference. Whether the difference is good or Bod, Obvious or subtle is up to you to decide based on what your likes are..

Ask anyone who has tried Hifi on a Carpet. u NEED a spike then