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My OB speaker

Wharfedale Speakers

jaudere

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Hello friends,

after reading a lot about speakers, i finally decided to go the open baffle way. just experimenting a bit. I bought a locally made 12" speaker, no specifications available. the shopkeeper said that it was a woofer but it produces decent higher frqes and has a whizzer cone so i think it is a full range speaker. I built H frame with help of a carpenter.

size of H frame: height: 3 ', width 20" and depth 2'. built it arbitrarily.
after putting the driver in the frame, i found it lacking a bit in higher frequencies. surprisingly, i found that the bass is pretty decent, although i do not have any measures. everyone who has built a OB speaker says that it lacks in bass but whatever bass my speaker produces is more than enough for me.

the sound: i like it. my wife and my neighbour unanimously say that it is better than my regular speaker ( I use NX audio 2 way bookshelf , a pro speaker).even I do not feel that the sound of my original speaker is that great when i do A-B comparison.

delighted by the results and i have decided to go 1 step further. My philips 8" full rangers are arriving tomorrow(which say that the frequency range is 50Hz to 22Khz). so it will be a combination of philips full range without any cross over and a woofer from ahuja with one way subwoofer cross over by ahuja again.

Ahuja Sound Solutions

Ahuja Sound Solutions

i know that people dislike Ahuja and think that it is only meant for PA systems but no other Indian manufacturer gives so much technical detail including T-S parameters of drivers. it has a decent price and most importantly, it is readily available.
 

moserw

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Depends...
As a kid my house was filled with Ahuja, Philips and Murphy. Only Philips has survived into the modern age...

Post some pics.
 

jaudere

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hi,

my philips 8" full rangers have arrived. very good at mid and high frequencies. not good at low frequencies but that was expected. so anyway i am going to use woofer.

bit of a confusion.which woofer should i use?

i am thinking in terms of 15" woofer. either JBL 15" car woofer:eek: or ahuja 15" AS X200 woofer.
Ahuja has lower X max(only 4 mm) but better sensitivity(98dB) vs 92dB of JBL. JBL has better x max(14mm). JBL Qts is .6 , better than .54 of Ahuja(Qts towards .7 is better for OB)

now why sensitivity is important? Philips has sensitivity of 92dB/W/m. Open baffle has problem in bass. so if i use a bass driver with 6dB higher sensitivity, naturally SPL produced by bass driver will be higher and that will partially solve the low freq. problem.
another point : JBL frquency response is 28Hz to 450Hz so no need to use low pass filter. Ahuja response is upto 1500KHz so i may need to use a low pass filter at 250Hz.

so friends, please let me know if you have any experience with JBLs or any thoughts about the comparison that i have mentioned above.
 

jaudere

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hello,

the philips drivers are working well. the H frame is working well with single driver. To my surprise, unlike what others say, I am not missing bass at all(my room is small with 12'x14').I have not used it for movies but it does very well for music. 1 full range driver is in H frame and others are yet to get a baffle. the larger is 12" dolbycon driver(locally made) and smaller is Philips 8" full range. no crossover as all are full range drivers. yet to get the real feel of OBs as only one sided speaker is working. will build the complete pair after i shift to new house in another 2 weeks.

some how my Rs 2700 Taiwa amp is giving better results than Yamaha as far as bass goes.(both amps kept at neutral/tone defeat position).for mids and highs, both amps are same. probably the dolbycon 12" full range drivers which i am using now with philips are better suited for this amp.the results may differ when i use Ahuja 12"full range.using larger driver helps a lot in bass dept. about volume, i need to go upto only 9 o clock position on taiwa while on yamaha, it needs -25dB to get same results.

after listening to this crude OB design, i feel that my original bookshelves are too bright /sharp. even in bass dept, the bookshelves need a sub but OBs are doing well without sub. i don't feel like listening to them now. probably i am rediscovering my musical taste

i am attaching links to the photos. don't look at the designs and aesthetics. i sure once i put those bare drivers on open baffle, they will work better. i am just trying many variations

Photo Sharing by MyPhotoAlbum.com :: MyPhotoAlbum :: MY OB experience
 

gobble

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Great Stuff!! Admire your DIY spirit!! Keep it going ... :)

Cheers
 

jaudere

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hello friends. Finally decided to go 3 way open baffle. I will be using speakers for music & movies. So philips full range may get damaged by sounds <50Hz heard in movies. So i have to introduce some protection for them. If i use 2 way crossover,most of the readily available ones cross at about 2khz. So i will lose part of the beautiful philips midrange. I am not an electronics man to build a crossover & to know the nuances of the components used. So decided to go 3 way. Here are the parts i am using. Bought them today in pune. 2 15" woofers by Greaton(made locally by order@rs 2600 a pair), 2 philips full range at rs600 a pair ,2 philips silk dome tweet at rs 500 a pair & philips 3 way crossover at rs 900 a pair. It doesnt mention the cut offs but someone who used them highly recommended. .
 

jaudere

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hello gobble. Will post some pics as soon as my home net starts working. I am writing on my mobile at present. Had another question. If i just attach an 8 ohm resistor in place of the mid , will the crossover work? Idea of using 3 way is simple. A 2way xo has am odd cutoff point. 3 way will have one around 600hz &second around 12kHZ. Now i want to play the mid without any crossover circuit in between. So what i can do is attach the woof & tweet through the xo to the fronts & direct the bass through the fronts only. I can attach the philips full range to the surround terminal. My yam receiver should split the signal into 4 streams. Front 2 will get full signal with bass but wont play midrange. The full rangers should also get full signal minus the bass. This way i may protect my full range from low freq & at the same time get purer signal to get to the full range.
 

jaudere

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hello friends. Finally i have found a carpenter who is ready to work as per my direction. So i should get my baffles in another 4 days. Then i will experiment with xo or no xo. If i use xo , i will use tweeter. If i dont use xo, i will use 1 woofer & 2 full range speakers , one stressing on mids (locally made) the other on highs (philips). Somehow,based on the experience i got till now, i feel that i am going to chose the design without xo for the final version.Still have to access the net on mobile. So difficult to post pictures at present. I have pics on mobile but the size is huge . So cant post it.
 

suprateep

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hello friends. Finally i have found a carpenter who is ready to work as per my direction. So i should get my baffles in another 4 days. Then i will experiment with xo or no xo. If i use xo , i will use tweeter. If i dont use xo, i will use 1 woofer & 2 full range speakers , one stressing on mids (locally made) the other on highs (philips). Somehow,based on the experience i got till now, i feel that i am going to chose the design without xo for the final version.Still have to access the net on mobile. So difficult to post pictures at present. I have pics on mobile but the size is huge . So cant post it.

we look forward to the pics jaudere. :clapping:
 

jaudere

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hello cranky. Thanks for a lot for that advice. Your post has created too many questions in my advice. 1)with what & how do you coat the cone?is it meant to increase the moving mass? 2) in my xo, from the capacitor, i guessed that the cutoff between mid& tweet is at 10-12khz. So i thought that should be fine for tweet. 3)what is meant by polar issues? 4)i read about off centre placement. It seemed to be a controversial issue. Some people including orion,JBL R909 favouring centre placement. So i am a bit confused. 5)what is meant by beaming by a speaker? Btw which pics of my speaker did you see? I am going to use philips round 25 w rms & the pics were of 15w rms hexagonals.of course they are from same company & full range.
 

jaudere

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wow! I am getting a lot of knowledge from you. thanks Cranky!

Use wood varnish, it's a nice enough substance, but watch the fumes. PVA glue was a possibility earlier, but natural varnish (not water-based) works fine.
>> what do you use to get an even coat? a finger with a glove on or a brush?

The coating provides a bit of internal damping, by changing the properties of the area it is located in, namely mass and stiffness. It also prevents cone breakup. The increase in mass is an associated penalty, not a design intent.
>> OB drivers are supposed to have minimum possible mass. won't painting affect it?




4. Almost all for-sale designs have speakers in the center. So do all designs with high WAF. The problem with off-center placement on an OB is usually the reduction of effective baffle width, but I'm no expert on that, you'll have to look it up. Check out the DIYA forums, and post a Q in the fullrangers section. They have the real experts.
>> I think this can be done by keeping the wings of different size for the baffle. probably will get same effect without having problems with aesthetics

5. Beaming is when different parts of a speaker begin to emit different parts of the audio spectrum. This generally happens when the driver diameter exceeds half the wavelength of the emitted frequency. In such a case, it no longer is possible for the wave to be emitted from the entire surface of the cone. A driver usually suffers from this when crossed over too high,and this generally causes poor off-axis performance and stray reflections. For an 8" driver, IIRC that is about 1.5KHz, and for a typical 6.5" mid, 2.5KHz.

>> I think this is a very important point. it seems that i must use a cross over. my woofer will perform poorly if it does not have low pass filter.

Now, if i am going to use crossover, do i need to do all that painting?
secondly, if i decide to build a cross over(In case i don't like performance of readymade philips crossover), can i use the same skeleton(Pics are on the way) to build a new crosssover?
 

jaudere

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Re: My OB speaker some pics

Here are some pics of the drivers .some old and some new. the carpenter has promised me to provide the baffles day after tomorrow..

i stay in a village and use BSNL tarang WLL for net with horrible speed. so i have kept the pics to the minimum possible size.

Hi gobble, you needed the tweeter pic. it is there .

Photo Sharing by MyPhotoAlbum.com :: MyPhotoAlbum :: MY OB experience

Photo Sharing by MyPhotoAlbum.com :: MyPhotoAlbum :: MY OB experience

Photo Sharing by MyPhotoAlbum.com :: MyPhotoAlbum :: MY OB experience

Photo Sharing by MyPhotoAlbum.com :: MyPhotoAlbum :: MY OB experience

Photo Sharing by MyPhotoAlbum.com :: MyPhotoAlbum :: MY OB experience
 

gobble

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You are doing great!! I read a bit about speaker building and dropped/postponed any ideas of going DIY. Not at this stage of my life. Speaker building and measuring can be complex hobby. Glad to see you keep at it.

PS: Whats the driver in pic 11? I saw a horn in it. is it an FR ?

Regards
 

jaudere

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You are doing great!! I read a bit about speaker building and dropped/postponed any ideas of going DIY. Not at this stage of my life. Speaker building and measuring can be complex hobby. Glad to see you keep at it.

PS: Whats the driver in pic 11? I saw a horn in it. is it an FR ?

Regards
Hi gobble,that speaker is philips full range. Pic 10 is its back view. The horn is called as whizzer cone & it is supposed to augment high frequencies.
Even i found this hobby to be very complex. Why i initially chose open baffle was because it was the most simple to create. But then i liked the sound so much(& that too without considring any technical points) that i decided to go for it. Secondly doing it diy way will always give you immense amount of knowledge which a ready made thing cant give you. I have attempted a diy projector twice which failed miserably . I could have bought an entry level projector in that money.But i dont regret it.i learnt so many things & i had attempted it with LEDs which was quite different from others. Now LED technology has advanced a lot. So i may waste some more money on it later. But for now , it is open baffle speakers!
 
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jaudere

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Hello cranky. thanks for those encouraging words. I am absolutely a novice in this field(by profession I am a critical care specialist). i am gradually moving forward with the knowledge i am gaining on this forum.

i thought that there is a bit of confusion in my mind.

Have fun, I think you will enjoy the sound. That Philips woofer can perform very decently (and outperform a lot of commercial hifi) when used right, and I think you're on the right track. Don't worry about the beaming too much, most commercial speakers I've heard below 1L crossover too high, and the beaming is pretty evident. You should not even notice it.
>> My woofer is going to be a locally made 15" driver and not a philips. beaming shouldn't be an issue if I am using XO. as i have said from whaevet values i could find on the xo, i think the low pass for woofer is around 600Hz.

secondly, i am going to use philips full range as my mid range. If i should believe in the SPL-freq graph given on the box, it should perform decently upto 10Khz. again from the capacitor value on XO, the cut off between mid and tweet should be around this value only. so the tweeter shouldn't face any problem and at the same time the full range speaker should perform decently. so again i think beaming shouldn't be a problem.

I am using yamaha RXV 361 which is a 5.1 AVR. it gives low pass cut off upto 200Hz. the problem is that the sub out is passive and i need active sub to use it. so another way to tackle this is to connect the woofer to the front speakers and full range/tweet to surround terminal. then i can adjust bass out through the front. this should be adequate to protect the full rangers from lower frequencies. if i connect a mid- tweet combination to the surround terminal, i will need 2way XO and there are many 2 way passive crossovers available in market. probably i will have to add a centre channel full range to improve human voice SQ.

at present i am using fullrange-woofer combination without any XO and i am unable to find out any beaming/combing or integration issues(the speakers are placed almost 2 feet apart). probably i should thank god that i cannot find these problems . i am lucky not to have that golden ear. or probably , the alternative reason could be the speakers have gelled well with each other. somehow i am not missing upper end either( or is it a fact that what happens to the ear at age of 40 has started earlier for me.:sad: I hope not.)


lastly, i am unable to find the TS parameters for that philips drive even after a lot of effort.r. can you help me out?

regards,
 

jaudere

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hi cranky.,
thanks for those references. I read all the posts again. then i connected my speakers through crossover. the woofer is working better. without XO , i had to keep bass setting at 4 dB. with cross over, i had to tone it down to 0dB. so probably the woofer had beaming problem and probably was not working well as it was trying to produce higher freq. am i right? so probably i noticed the beamimg problem after it disappeared. But this made one thing sure. I am not going to miss bass on OB at least in music. I will have to try it in movies.

About T/S parameters, i think they were important for OB as well.

eg: Fs: building a box increases the resonating freq. but with OB , FS is not changed as there is no box. so probably a woofer with Fs 33 but in a box will have same resonating freq as compared to a woofer having Fs 45 put on OB.

MMs: Lower the Mms, better for OB as there will be no assistance from reflected waves.

xMax: no box , no protection. so it needs to have higher xmax.


of course i do agree that T/S parameters are not important for building a crossover
BTW, can you please explain me what is exactly meant by Q of a speaker? i know that there is mechanical and electrical and total Q . but what is Q?:mad:


Regards
 

jaudere

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hello cranky. Thanks for that explanation. That clarifies a lot of doubts. Just wanted to clarify one thing. I am not using philips full ranger to drive lower freq. I am using a separate woofer for that purpose. With the cross over in the circuit, philips fr is working as midrange driver. If you see the pics in my album, the driver actually mounted on baffle is the woofer(locally made). The philips is on the top of the box without any baffle. i like the mids produced by it. One more question. How do you remove the whizzer cone?
 

Hiten

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Hi jaudere
Sorry for joing in late. But you have done a good job. Finishing and workmanship is superb. I hope material you are using for cabinet is particle board or soft board, so sound waves inside the cabinet doesn't bounce back or you can use layers of cotton inside the cabinet. Old Philips stereo wood speakers used to have them. (Ignore this comments if you have already thought of that)
Keep up the good work and pl. put pics of finished product.
Regards
Hiten
 
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