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Full Range Standmount using Boston HQ48414P driver

Wharfedale Diamond 225

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sachu888

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Very nice build Aashish. FM nraghunadha has also built one pair of bookshelves using same drivers. They sound very good. Here are few raw pics in testing mode:
Note: front baffle is not glued in pics.







Regards
Sachin
 

aashish351

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Thanks Sachin. Very neat and nice construction by Nraghunanda. Would you know how has he decided to damp the box finally for best performance?
 

sachu888

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He has pasted Bitumen sheets on all walls and Dacron/Polyfill for stuffing. I think you can avoid Bitumen sheet, and only light stuffing of Dacron or Glasswool.

Regards
Sachin
 

aashish351

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I agree, can avoid bitumen. I have been suggested, that a layer thin felt cloth (1-2mm) can be pasted with over use of glue. This can also work in place of bitumen. And, I already have felt and polyfill roll.
 

aashish351

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Not connected for trial yet Sumata... and I am out of town now. So it will have to wait a week. In the meantime, my person will get lining with felt finished. I will post an update once that is done.
 

vapmax

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Nice build! i also got a pair of these drivers from analogadikt. if you dont mind share the part of the book that you used with me too. i also like to make one with exact dimensions prescribed for these drivers.
 

aashish351

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Nice build! i also got a pair of these drivers from analogadikt. if you dont mind share the part of the book that you used with me too. i also like to make one with exact dimensions prescribed for these drivers.

Sure, send me your mail id.
 
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Sumanta

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This driver, if it is absolutely the same as Philips HiQ one, plays wonderful mids. Treble is more towards rustic, free but not so refined.

Bass is fast, lack depth beyond 250 Hz as per my ear.
For music, it is too good for its price.
 

analogadikt

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Nice build! i also got a pair of these drivers from analogadikt. if you dont mind share the part of the book that you used with me too. i also like to make one with exact dimensions prescribed for these drivers.
Pm me your email ID.

Regards,
 

tnvijay

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Very neat build. This sure is a wonderful driver. A few suggestions. Do a 98 cent mod. i.e. stuffing of polyfill between maincone and whizzer cone. if will help reduce the midrange shout. Consider a BSC or add a subwoofer for a F.A.S.T. Setup. The later one will be a best sonic option.
 

aashish351

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Very neat build. This sure is a wonderful driver. A few suggestions. Do a 98 cent mod. i.e. stuffing of polyfill between maincone and whizzer cone. if will help reduce the midrange shout. Consider a BSC or add a subwoofer for a F.A.S.T. Setup. The later one will be a best sonic option.
Thanks Vijay! I will try the polyfill behind the whizzer cone if the performance is shouty. Ideally I would like to avoid any passive electronic components. Regarding sub-woofer, actually, only today I was thinking that if the bass performance is not up to the mark I might consider adding separate stereo bass modules and place the speakers on them, use active crossover and bi-amp this system.
 

tnvijay

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@ashih . yes .Biamping with twin subs will be a killer combo. I
Adding a sub, crossed well below delivers that low end grunt and punch.
 

aashish351

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The project was on hold because of traveling and other engagements. Will post update after 2 weeks. I'm traveling again till then.
 

aashish351

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Hello everyone! Sorry about the long gap as I was traveling. Before I traveled, I had made some progress which I could not update. The speakers were brought home to the listening room. Gasket lining done around the battens for baffle and around the cut out from driver. Polyfill (2 layers - total 40mm) filled along with the foam on all sides. The drivers were fixed using screws. I have connected the speakers without finishing and given them a test drive. Surprisingly decent for the money, but as expected - shouty and not much bass. I agree with a previous post about treble - its smooth, rolled off and definitely not refined but listenable.

I removed the foam from the cabinet and and only left felt lining and polyfill. There was definite improvement in the upper & lower mid-bass. It was now reasonably full bodied although one would still define it as lean. I also think there is non-uniformity in the frequency response as I can hear an occasional bass note which goes relatively low. This could be due to less than ideal damping or mismatch in port design (Don't know if I mentioned, but the port length is as per design, but ID is 2.75" as opposed to suggested 4").

After returning from my trip, I have tried increasing the damping in the box more. I doubled the polyfill. The box is now relatively full but not packed or overstuffed. Not much difference - actually it has been slightly negative. So I think 2 layers of polyfill (double sheet) is as of now what looks optimum.

I have not observed any hollowness or boxiness, so I think the box is not vibrating or resonating. Well, the MDF is 18mm and fixed with battens! So, I am going to try removing polyfill altogether and see if the bass increases without introducing any boxiness. There is anyway a 2mm fevicol-pasted felt lining on all sides (except front).

To control the shouty-ness, I did try light polyfill stuffing between whizzer and main cone. It is a decent mod and must admit it works - but - ever so slightly. I would still not listen to it this way for long duration. I must mention that some songs sound quite decent and attention does not go towards midrange harshness. These may be the few which probably don't have much energy in the range where this speaker is shouty.

Also with vinyl the overall the sound appears less shouty than with CDs/FLAC files!! It sounds more like a mid/vocal centric speaker but definitely less shouty. But I guess that is true for most systems and is beyond the scope.

In summary, it has not been a great build in terms of sound quality that I have come to expect after years in this hobby, but, there are still basic things to try to improve it - BSC, Stuffing, Port tube. And then there are more drastic things - like equalization, adding bass modules or trying a different full range 8" driver (the cabinet construction is very good and I am sure the volume will suit other similar drivers).

The photo album is updated and can be found here - https://goo.gl/photos/vg42UXjkUgDdnUDB7. I also have some videos (shot through iphone though so not amazing but give an idea!) which I have to figure out how to share with those interested - suggestions? Just for info - the beautiful floorstander seen in the pictures is also custom made (not by me) using a coaxial Focal JM Lab 2-way driver. It is very professional work. These are my main speakers these days and have phenomenal bass response for the 6" driver. Very clever designing and construction by FM Pranav Kumar (Acoustic Science). Anyway, lets focus on the Hi-Q!
 
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aashish351

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So I have removed all the polyfill and there is very slight increase in boxiness (which is negative) but there is also a noticeable increase in the full bodied character of the sound (which is positive). It does seem to have reduced the shoutyness a bit but ever so slightly. I am going to put back 2 layers of polyfill to confirm this.

Over more listening, I am realizing that the sound has a strong electric guitar-like character as if this is a guitar amp monitor. So earlier when I mentioned some songs sound more balanced than other, I think it is the frequency range between 2k to 5k which is the problem.

The more I read about FR drivers, the more I hear that shout is a common problem and a BSC/notch filter/Zobel network is the solution. So I might look into it more.

I am also going to do another experiment. I am going to remove the front baffle from box and listen to it just as an open baffle. The idea is that if there is nothing much I can do to improve the bass in the box (which is also important to make this a listenable speaker), then I will convert the box into a bass module by adding a woofer and low pass filter to cut 100Hz and above. And fix the open baffle with the FR on top and give it mid and high duties with a BSC to even out the mid-high response. Any thoughts?
 
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