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Old 29th September 2008, 06:46 PM   #1
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Default passive radiator question

Hello. I just bought a bunch of old speakers. A pair of realistic mc-1200, a unmarked pair of sony and another brand with only a symbol. I will post some pictures later to give more information about my dilema.

My dilema is that the sony pair had blown woofers. probably because they said they could only handle three watts on the woofer. The box is about one cubic foot has a 2 inch cone tweeter, the 8 inch woofer and a 8 inch passive radiator. The problem is i have no information about the system or radiator.

I was wondering if there was a way to make measurements on the passive radiator which will then let me implement is correctly when finding some new woofers. i have some fullrange 8 inch pioneers b20 that i shoved in for the heck of it. the music sounded trapped which made sense for such a small box.

Anybody have any other ideas on what i could do? maybe get a already known radiator and then a new speaker as well. maybe close of the hole or implement 2 woofers that can handle such a small box.
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Old 29th September 2008, 07:04 PM   #2
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I would remove the Sony woofer, passive radiator and tweeter and make a new front baffle to fit the Pioneer B20 and the Sony 2" tweeter. This will leave you with a sealed 1 c/f box, the B20 and tweeter. Remove any components connected to the tweeter and play with different capacitors. I would suggest starting with a 2uf capacitor connected to the plus on the tweeter. If there is too much treble try a 1uf capacitor. Listen to different values until you find the tweeter and woofer blend together nicely. Leave the B20 to play full.

That's what i would do.

http://www.zillaaudio.com/pioneerb20-3cubox.htm

Click the link to see a simulated response on a 1.3 c/f sealed box using the B20.
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Old 29th September 2008, 07:21 PM   #3
sreten is offline sreten  United Kingdom
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Hi,

Stuff the box well and it will get near 1.3cuft effective volume.

I can only guess an ABR for a 3W 8" driver is next to useless
for anything other than another high Fs low wattage 8" driver.

/sreten.
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Old 30th September 2008, 02:08 PM   #4
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Here are some pics of the speakers. first one of the sony speakers had some odd replacement woofer. Actuallly a fullrange speaker made by B.P. Electronics. That speaker actually sounds pretty good. Sounded better than the b20 shoved in the box. Anybody know anything about this?
Click the image to open in full size.

Click the image to open in full size.

Next is that unknown speaker brand. Unknown to me atleast. i didn't see a good way to get to the speakers either.

Click the image to open in full size.

Click the image to open in full size.

This is the box the sony's were in. No terminal on the back just wire stuck through. no stickers on them. stapled on radiator. The radiator is the cone and surround and nothing else.

Click the image to open in full size.
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Old 30th September 2008, 02:35 PM   #5
sreten is offline sreten  United Kingdom
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Hi,

I assume the radiator is the same cone / surround as the original.
Have seen this before were the magnet and coil is missing but
omitting the frame is a new one on me .......

Show the back of the unenterable speaker.

/sreten.
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Old 30th September 2008, 05:10 PM   #6
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Yeah I know. The radiator is retarded. it is the same cone surround as the woofers were. i reached back and just felt cone and was disappointed. I did take into account it was Sony then wasn't surprised anymore. Damn Sony.

I will put up a pic of the back as well as better shots of it when i get home. I am at the doctors waiting to get some medicine! stuffy nose is all so far. Hopefully you will see something.
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Old 30th September 2008, 07:15 PM   #7
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okay all the pictures are located here. I don't want to crowd this with huge images. the last thing is a video of me showing the back edges. very poor shooting. don't get dizzy. i think someone glued it shut or they were like that.
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Old 5th October 2008, 06:53 PM   #8
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Okay. So I made my plan on what to do with the boxes. I bought some cheap components from parts express and I am gonna throw them in. I bought the buyout 8" inch woofer to fit one 8" hole. Then eight inch waveguides will fill in the other 8 inch whole. They will be milled down to fit 1 inch dome tweeters. Then to fill in the old tweeter hole. A 2"radius x 5" long port will be used. i wanted to go with some actual horns but i wanted to match the 4 ohm woofer. so to still make this cheap as hell I am going to fit in the domes.
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