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Old 30th July 2007, 02:20 AM   #11
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looks like I started a popular thread here!


Anyways, I used the 1uf metalized film caps from the shack. I don't have any inductors in there at all. Ont thing I am noticing is distortion.... The tweeters in the speakers don't distort as much, then again they do not go quite as high, even though they are metal domes. I am thinking it is my amp at fault, having nasty distortions in the upper end of the audio spectrum, but am not sure.

Can tweeters cause audible distortion? Maybe I am feeding them a range they do not like?

I do not have any specs, but they are way upper mid/tweeter/upper tweeter range Magnavox horns from a Magnavox Astrosonic console.
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Old 30th July 2007, 04:12 AM   #12
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I found some specs online: they are 8 ohm alnico IV ( ) and are rated at 40 watts from "1khz up". No upper limit specification....
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Old 30th July 2007, 06:14 AM   #13
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You're crossing over really high-almost 20 kHz.

I'd use a 4.7 uf nonpolar capacitor bypassed with your Radio Shack 1 uf metal film.

That will cross you over at around 3.5 kHz-still high but not unreasonably so.

One thing that did occur to me was that perhaps your tweeters have much higher efficiency then the rest of your speaker system. That would explain a few things you've explained, as you'd be using the Xc of the capacitor as a way to reduce the level into your tweeter. The better way to do it is to use an L pad between the crossover and the tweeter. You can also use a resistor in series with the tweeter if you calculate its effect on the crossover (it will lower the frequency).
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Old 31st July 2007, 01:12 AM   #14
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doh! didn't think of that! My metal domes SHOULD be reaching up pretty high, I think that maybe my x-overs may need some attention? The tweeters are not very loud.. This is why I added the horns.

I will try an Lpad though! I don't have some right now, I do however have some 8 ohm power resistors I can try.

I wonder how much replacing the caps in my x-overs would change/bring out the sound? They are all over 30 years old...
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Old 31st July 2007, 01:26 AM   #15
omni is offline omni  United States
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I'd like to see your current crossover schematic.........Along with the drivers you are using
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Old 1st August 2007, 03:38 AM   #16
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gah! I tried to trace it once, gave up because of the tapped inductors. The speakers are Sansui SP-1500's,

For my magnavox horns I just have them running directly off of the main in through the cap and to the horn. Seems like thats the way they were set up originally too, however they may have had a resistor too.

Anyways... My original tweeters were 16 ohm sansui metal domes ( two per cab). I blew them in an amp connecting mishap and found an original set on ePay. However, the new set does not sound as loud as my original ones did, so it is possible I did some damage to the caps too. I believe the caps are all 50v. The amp was 100wpch.

If you are not familiar with the model, they use two 1 inch 16 ohm metal dome tweeters, One 6.5" AlNiCo V midrange , one 5" AlNiCo V upper midrange, and one 12 inch woofer, 2" voice coil and 6.5" ceramic magnet, treated inverted cloth surrounds. SP-2000's and SP-200's got AlNiCo magnet woofers
Wish I had those because these are HEAVY!

All this is housed in a 1" thick MDF cabinet with 1/4" walnut veneer and thick 1960's style diamond accoustical dampening material (looks like its made of rockwool or pressed fiber scraps)
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Old 1st August 2007, 09:14 PM   #17
omni is offline omni  United States
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Dude, it appears that you are at a dilemma as to how to proceed with your upgrade project......... You might start by checking out www.partsexpress.com ........and Madisounds website........Parts Express is here in Ohio, and you can get some education and also purchase those caps you may need, but I am wondering, from what you describe you don't have any idea as to the component values of you capacitors or inductors?....If you are looking for value oriented capacitors, you may want to check out the Solen line that Parts Express carries or their house brand they call Dayton.............These are metalized polypropylene, which is what I would recommend.......Are you looking to rebuild the crossover entirely or simply replace a few caps? You seem unsure of whats inside.........To what extent are you willing to go and what are your expectations.........these are the first questions I would ask......Respectfully.......Omni
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Old 2nd August 2007, 01:48 AM   #18
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I do know what is inside, I just havent had the backs off since I restored the speakers. All the caps are nonpolar electrolytics. The inductors I have no way of telling what value they are, however all I am wanting to do is replace the electorlytics with new caps. I have heard several reports of these speakers beginning to sound a bit muddy when the caps start to go bad (lack of high end). They replaced the caps in the x-over and all was well again. Some said they competed with their B&O'. Anyways , I would still like to uses these horns in additon because my future plans are to gut the x-overs and triamp the speakers using a gainclone for the woofers, a PP tube amp for the mids and a SE tube amp for the highs.


However as of now I would not object to buying some nice quality caps for the X-overs. I'm sure caps from partsexpress are going to be overpriced... I will get them somewhere else like tubesandmore,tubedepot, mouser etc.
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Old 2nd August 2007, 01:50 AM   #19
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Back on topic I am still trying to figure out why I am having noticable distortion out of the horns .. even at low volumes they sound grainy. I never heard the console, but I cant imagine they would have noticable driver distortion...
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Old 2nd August 2007, 02:20 AM   #20
omni is offline omni  United States
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Dude.........On the caps, suit yourself as to where to buy them......Where ever you feel comfortable is your call...........cool.........I do doubt though, that Parts Express is gonna be overpriced, but it's your call..............On the horns.........I am curious how old they are.............Back in the 70's I built a 3 way with the familiar Electrovoice Horn Tweeter.............It was at that time reported to be filled with Ferrofluid...........By the 90's, they started sounding raspy and harsh.............Finally, I blew a resistor out in the tweeter section, and because of the harsh sound, I decided to build a new system.............So I decided to perform an autopsy on the tweeter.........I took it apart, checked inside the voice coil, and found no Ferrofluid............I began wondering that after 20+ years that maybe the Ferrofluid dried out, or leaked out somehow............perhaps causing the harshness that you now seem to be experiencing with your horns .....Who knows.....Just a theory...........Another possibility..........your electrolytics may have leaked and dried out.............At any rate, I would go with the metalized polypropylenes.....no question.......Respectfully.........Omni
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