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 Post subject: Re: DIY speakers
PostPosted: 06 Sep 2008, 09:28 
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Hi Sabs,

Most plate amps have a built in variable active crossover, so you should not have to worry about that. Can you post a link to the plate amp.

I'm not too crazy about both of those drivers. The Eminence strikes me more as a bass guitar driver and the Visaton W 250 S 4 OHM seems better suited to a two way application. Can you post a link to a store that is close to you.

Cheers

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 Post subject: Re: DIY speakers
PostPosted: 06 Sep 2008, 16:09 
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Joined: 04 Sep 2008, 09:35
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Location: Menton, France
Hi guys,

this forum is like a diy wikipedia!!!!!!! I'm busy taking loadsa notes.

Ok first up this is the shop link
http://www.toutlehautparleur.com
they have a large selection, but a lot of the makes I don't know. so when looking i used some advice i gleamed from the project pages.

My main yamaha amp, does have a dedicated sub output, and the plate amp i found is not on the web, but i have a spec sheet in PDF format which i have attached.

Of course if you have other idea, i am like a sponge, ready to absorb.

Sabs


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 Post subject: Re: DIY speakers
PostPosted: 06 Sep 2008, 16:22 
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K. SO with that amp you can vary the low pass filter so that the sub will only produce your selected frequency and less. Thats good. Its only a 50W at 8ohms and 70W at 4Ohms amp so you need a very efficient driver.
I will check out the site. Am sure others will to and make sub suggestions.
Ri

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 Post subject: Re: DIY speakers
PostPosted: 06 Sep 2008, 17:55 
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How much are you looking to spend on the subwoofer driver?

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 Post subject: Re: DIY speakers
PostPosted: 07 Sep 2008, 04:29 
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About, 100 euros thats about 150 US$, However like in most cases if you think that pushing this a little higher will result in a better sub then i'm all ears.

Ri when you talk about a more efficient driver, in what respect does it have to be more efficient?


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 Post subject: Re: DIY speakers
PostPosted: 07 Sep 2008, 09:17 
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You can try the Monacor SP-250P up in WinISD. My French is not good, but I could not find a price. Also, the JBL GTO 1002D and JBL GTO 1004D look decent, but the 1004 is 8ohms. Most 4ohm car subs will do the trick so don't rule out local places where you can go pick one up yourself. Just be sure to run the numbers first.

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 Post subject: Re: DIY speakers
PostPosted: 07 Sep 2008, 12:44 
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Efficiency is rated at decibels per one watt at one meter. SPL Sound Pressure Level.
See this website
http://colomar.com/Shavano/spl.html
Basically, how much sound can you get with one watt? You want this to probably be in 90+ range. Why? Because:
At one meter 1 watt gives 90db
2W=93db
4W=96db
8W=99db
16W=102db
32W=105db
It is said that we can tell a 3db increase and that some can identifiy a 1db increase so the difference of a few db is small to your ear and our hearing is logorithmic. The louder it gets the less we can tell its getting louder. So you need a very high db on that first watt.
Assume you started with 85db=1W
2W==88db
4W=91db
8W=94db
16W=97db
32W=100db
Many subs go as low as even 81db for that first watt, and remember this is at one meter and you will be sitting 2-3 meters away which will cut that db in half.
You can buy speakers that begin at 105db for one watt so you can see where when you are using a small amount of wattage that a high efficiency speaker is very important. You are going to want to have great use of that 50W and if you start off with an inefficient speaker I think you will be disappointed.
Ri

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 Post subject: Re: DIY speakers
PostPosted: 07 Sep 2008, 16:58 
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Cheers Ri, well explained. i understood it the first time.

and g when you say run the numbers, is that with regards to Unibox,(see other post) or efficiency and ohm ratings?

I will get this nailed.......promise!


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 Post subject: Re: DIY speakers
PostPosted: 07 Sep 2008, 18:21 
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I think he means to get specs associated with the driver and put them in WINISD and it will create a box design for you.
Some important things to consider.
Your amp only plays 165Hz and less. So even if you get a sub that does wonderful at 300Hz you are not going to use that part of it. I hope that your main speakers will handle somewhere between 100 and 165 well so that you have a clean transition from woofer to main speakers.
IRT the amp only covering 165 and less you will want to make sure that the woofer you select has a very flat response curve (SPL/Frequency) from somewhere greater than 165 to somewhere between 30 and 40 or even lower. I think we stop hearing music at around 16Hz but you still feel it.
So you should look at the specs of your main speakers and find how low they go and pick a woofer that has a flat response up to at least a little higher frequency than the lowest frequency that your main speakers are flat at. That way you have a smooth transition from main speakers to sub.
These numbers are available on most speaker sales websites and you will see a graph that shows the SPL at certain frequencys. SO in the last post we talked about Sound Pressure Level at one meter with one watt. When you look at this graph it will show you the SPL on each specific frequency with that speaker at one meter with one watt. With regular Full Range speakers they usually start to have higher SPLs at higher frequencies which means at one watt with one meter the higher frequencies are actually louder. Woofers are usually flat from around 30Hz to a few hundred or sometimes a few thousand and then drops off significantly.
Take http://www.madisound.com/catalog/produc ... cts_id=301 for example.
This one is flat from 150 to 5000Hz. It has an FS of 29Hz which is as low as it can perform well.
Notice that when I say the SPL/Frequency graph is FLAT that it is flat at about 90SPL. Lets imagine that is your main speaker. The sub to match it would have to be FLAT from anywhere over 150Hz to less than 30Hz. ALSO that same sub would be nice to be FLAT at around the same SPL of 90db but that is only very important if you are driving it from the same amp as the other two speakers. In this case you have a separate amp and will be adjusting the volume on the sub separately. If driving from the same amp and the sub was FLAT at about 100db.... well then the BASS would always overwhelm the rest of the music unless you built a small circuit to allow it less wattage at the same volume setting.
On the link I showed you you will want to take notice of all the specs that are right below the picture of the driver. You dont really have to know what they mean but you have to place them into the right input boxes in WINISD.
One more thing. Vas means how many liters the driver needs to perform at its optimum. So if Vas is 100 you will need a 100liter enclosure. A quick way to decide if this sub is for you is to check the SPL, Vas and FS. So, how efficient is it, how big of a box does it need and whats the lowest frequency you can expect.
Ri

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 Post subject: Re: DIY speakers
PostPosted: 07 Sep 2008, 18:37 
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http://www.nulltime.com/DIYAudio/subwoo ... /patl.html
Dont go to crazy :)
This one looks fun.
Ri

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