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Old 21st January 2010, 07:48 AM   #1
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Join Date: Feb 2006
Location: karnataka
Default Need Feedback and Opinion !!

Hi,

Hello folks I would like to inform all that I've managed to get a driver custom made (call it Semi DIY if you will )

I at this point in time will not divulge the details of where and how this was done and such,the reason being I want this thread to be concentrated on the driver and qualities,merits/demerits etc rather then people talking bout where,how and why was this done etc etc etc.......

I will comment on that at the appropriate time,please understand !!

I also had in between contacted Sumit for his own driver which he had readily agreed to do but I just couldn't get done due to 1000 reasons ! will surely get his driver too (Sumit you reading,Am waiting for your mail) !!

Anyways without too much into these stuff how difficult it is to source good drivers (there's already a special thread by the same name) and all the blah blah's,I'll straight come to the point !!

As Said above I've got this driver and asked a friend who is very well known in Audio Circle (L@y@ A****tics) to measure the TSP !

I want all the folks here in DIYA to comment on the driver (merits and demerits all the lowdown),any improvements that can be implemented or done to make it even better ??

Some Plans for further improvement I have :

Venting the polepiece (6-8MM)
Treating the Cone with some Coating ( with what please suggest )
Adding a Phaseplug In Lieu of dustcap.

Please do let your views on the above as well !!

Now for some Basic details :

Size : 6.5
Motor : 120MM magnet with 8MM top and bottom plates
Polepiece : 31.5MM
Voice Coil : 32MM Dual Layer wound in 32Guage wire
Spider : 100 MM wide and 10MM tall
Cone : Air Dried with Rubberised Form Surrounds

Some Pics of it for reference !

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.


Here's the TSP measure by said friend !

First set of them without any hours on them (or max less then 1hr)

Re :6.8487
Fs : 47.3723Hz
Zmax :186.0971 Ohms
Qes :0.3228
Qts :0.3109
Qms :8.4475
Le : 0.7287
Vas : 25.8084 L
BL : 8.7027
Mms : 11.9917g
Cms :941.2622
Sensitivity :90.546@ 1M /1W

Second Test results after some brief burn-in using 25Hz Sine wave

Re :6.844
Fs : 47.42Hz
Zmax :186.72 Ohms
Qes :0.3244
Qts :0.31
Qms :8.5251
Le : 0.7287
Vas : 25.8084 L
BL : 8.82
Mms : 12.398g
Sensitivity :90.88@ 1M /1W

After 5 Hours of 25Hz sinewave !

Re :6.88
Fs : 43.8792Hz
Zmax :177.1931 Ohms
Qes :0.3000
Qts :0.2883
Qms :7.4175
Le : 0.7308
Vas : 26.9775 L
BL : 9.2001
Mms : 13.3713g
Cms :983.8979
Sensitivity :90.546@ 1M /1W
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Old 21st January 2010, 10:50 PM   #2
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Did you design this as a mid-bass? a Freq response graph would allow a more useful evaluation.
sd=? Using a guestimate of 140 cm sq. Unibox shows it's OK down to mid 60s in 10L vented; an EBS alignment will get it down to the low 40s in 25L
Personally, I'd prefer to get down to the low 40s with QB3 alignment, but I suppose that'd be at the expense of higher Vas?
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency

Last edited by PeteMcK; 21st January 2010 at 10:52 PM.
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Old 22nd January 2010, 12:24 PM   #3
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Hi,

Thanks peter for the reply !!

As to the question you asked,the Sd was taken as 135.6cm Sq !!

The Freg Response Graph is with that mentioned friend only will collect it and post later !

About the Fs I expect it to come down as the driver reaches its saturation (or after say 50+ hours of burn-in)

Hmm only one person was kind enough to post what bout other ??

Regards.
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Old 22nd January 2010, 12:44 PM   #4
godfrey is offline godfrey  South Africa
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Each time you burn it in, the magnet gets stronger and the cone gets heavier

Looks like a hole in the back plate next to the pole piece. What's that for?

Looking forward to the freq response graph(s)
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Old 22nd January 2010, 12:48 PM   #5
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Just looking, it's a good work from you and factory (team work). I like/prefer rubber surrounds though. Fs=40's is a good mark/achievement for that size of speaker to star with. Qts=20's is best too. Le is high, must have a very good roll/natural/high order at 4 xo point. The pressed steal basket is a no-no, but good for a entry point speaker driver made of good quality materials, tech can move 4 a complete line of drivers, as I see and depending of the numbers (units) you sell, generally more than the 300(/100?) mark. Let's see the curves... Congratulations.

Last edited by Inductor; 22nd January 2010 at 01:03 PM.
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Old 22nd January 2010, 02:35 PM   #6
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Hi,

Now we are talking !!

Quote:
Each time you burn it in, the magnet gets stronger and the cone gets heavier
That's something I was wondering too !! Although illogical cannot completely rule out as the measurements are done using the normal methods and not by some super highend one's like CLIO,KLIPPEL or LMS !!

Quote:
Looks like a hole in the back plate next to the pole piece. What's that for?
Thats for VC cooling,I had plans for venting the polepiece for the same but went with this idea as to see how this reacts,in the next set of samples I will have the polepiece vented !

As mentioned earlier Am even looking at a phaseplug design !!

Quote:
I like/prefer rubber surrounds though. Fs=40's is a good mark/achievement for that size of speaker to star with. Qts=20's is best too.
The Rubber surround will work too,but will have some small time issues with mid band,so overcome that this was used (earlier had tried with pure rubber too) !! The Fs Am expecting to end within 30's or max 34-36 !

Quote:
The pressed steal basket is a no-no, but good for a entry point speaker driver made of good quality materials,
Well you are right,but to even get this in a country like ours is pain !! but Am working on that too,Am in a process of getting mould made which will be used to make Alu Baskets (have got sample baskets but needs minor changes,so working on that)

Quote:
tech can move 4 a complete line of drivers, as I see and depending of the numbers (units) you sell, generally more than the 300(/100?) mark.
Am sorry but I didn't get it,could you please explain ??

Regards.
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Old 1st February 2010, 06:18 AM   #7
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Hi,

Hey guys what happened ?? So many experts and knowledgeable people and not one wants to even take a look at this ??

Whats so wrong in this thread that no one wants to post a feedback or reply ???

Anyways here's some more info on the driver !

Click the image to open in full size.

PLEASE GUYS give me some feedback !!

Regards.
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Old 4th February 2010, 01:58 PM   #8
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Hi,

Common guys some replies please !!

What the hell did I do wrong to not get any reply ???

Regards.
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Old 5th February 2010, 07:31 AM   #9
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Shoud you wish to coat it for extra rigidity spray a couple light coats of oil based spray urethane or clear plastic coat to protect and give some rigidity and ad 10 or 15 grams of clay or silcone to the voice coil cap ( this will shift the fs a little lower in the FR and may reduce cone break up in the higher range
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Old 5th February 2010, 07:32 AM   #10
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you will definitely need a zobel network, which I bet you already knew
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