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 Post subject: Re: DIY speakers
PostPosted: 08 Sep 2008, 06:37 
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Joined: 04 Sep 2008, 09:35
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Location: Menton, France
Cool, so i have to think of the sub as part of the whole system, instead of a suppliment to an existing set up.

Great ok now time for extensive research, i did the monacor sp-250p and the results it gave actually made sense, now i have to see if this fits with my system at present.


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 Post subject: Re: DIY speakers
PostPosted: 08 Sep 2008, 07:55 
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Let us know the specs of the speakers you already have.
I am glad you figured out the software. My bet is that you will not be happy with that SP250P.
Image
The curve shows this speaker to be a bit more of a midrange/bass speaker than a subwoofer and your plate amp is definitely for a subwoofer. Notice how from 150 - 1kHz the curve is mostly flat? This is what you would like to see for 150Hz and LESS. This speaker will start to lose volume at 150Hz and less. The lower the bass the less volume there will be.
Ri

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 Post subject: Re: DIY speakers
PostPosted: 09 Sep 2008, 11:47 
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Funny you should say that Ri, when i used winISD with the monacor, the spl graph gave me Zero db up to about 20Hz then a gradual increase. I thought it was a bit funny for a bass!!!!!!

For the others, well, how can i get you the winisd files so you can see the others?


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 Post subject: Re: DIY speakers
PostPosted: 09 Sep 2008, 12:06 
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First time I used WINISD was when we posted about it in this thread. I dont know how to transfer files around. Maybe you can do a print screen and cut out the graph and post it? Or export as a jpg or something.
Ri

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 Post subject: Re: DIY speakers
PostPosted: 09 Sep 2008, 17:47 
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Hi Sabs,

I suggest for driver selection you start with ISD Online as it only requires 3 parameters - Vas, Qts and Fs. Take a look at the attached screen shot
Attachment:
ISD-Online-Monacor-SP-250P.jpg

All I did was enter the Monacor SP-250P T/S parameters Vas=115L, Qts=0.33 and Fs=33Hz. Then click the "optimum" and "draw it" buttons under Vented.

The graph is the result for a vented box of volume 59.26L and a port tuning of 40.52Hz. I would do this until you find a driver that you are happy with as it is quick. Once you find something you are happy with, you can plug it into a more elaborate program.

Hope this helps.


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 Post subject: Re: DIY speakers
PostPosted: 10 Sep 2008, 10:04 
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you see i got the same graph in the program version. But for a bass is it normal of it to have zero db at 10hz?

I've done the same on the jbl which gives about -10db at 10hz for a similar box size and frequency of 29.36hz, it seems to me that this is more of a bass orientated driver. but would the monacor give a tighter sound being that it looks more like a bass/mid like Ri said?


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 Post subject: Re: DIY speakers
PostPosted: 10 Sep 2008, 12:29 
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the.sabs wrote:
you see i got the same graph in the program version. But for a bass is it normal of it to have zero db at 10hz?

That is most likely just a reference point.

It depends on what you want to listen too. For music, you typically don't need bass all the way down. The MAW-10 design you were originally looking at is about -15 dB at 20Hz. It is pretty good for HT and music, but a lot of people would prefer much more bass for HT applications.

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 Post subject: Re: DIY speakers
PostPosted: 10 Sep 2008, 15:50 
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Well guys, the first step is done I'm gonna go with the JBL GTO 1002D.

It's 4 ohms, with a sensitivity of 91 dB 1W/1m. this means the plate amp i have can run at 70w and this gives me more power on an efficient driver. the WinISD, also gives me a decent box size without being massive, i found a dynaudio driver that for a optimum graph gave me a box size of 115L!!!.

I will mostly use it for music with a bit of HT, so i think it will have a similar sound to the MAW. Thanks G.

The only downer is it looks a bit flamboyant! check it out
Attachment:
GTO1002D.pt.jpg

So i'm probably gonna have to go with a dark colour box, so I'm gonna buy some black vents and not make them like G.


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 Post subject: Re: DIY speakers
PostPosted: 10 Sep 2008, 17:13 
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I think that driver will do a fine job for your intended use. Also, I don't find the looks offensive at all. It should look good in a black box. Real ports are fine. I made mine because I could not find any locally and I did not want to mail order. Also, don't forget some stuffing material.

Cheers

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 Post subject: Re: DIY speakers
PostPosted: 10 Sep 2008, 17:49 
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Or you could make it a downward firing woofer or build a grill. Its pretty easy to do. JBL is pretty good stuff. When I went to the local audio superstore I liked the JBL sub they had best. Glad you found one to suit your purposes :) Now the real fun begins.
Ri

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