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Custom speakers, blown tweeters and a few questions..


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Hi,

 

I've recently been given a couple of speakers which are in need of repair.  I'm a bit of a novice but here's what I know so far:

 

Maker: Unknown (looks custom)

Tweeter 1: Magnavox - 15 Ohm, "XJ3"

Tweeter 2: Marantz (I think, based on model number), 8 ohm, "ST-10G1A", "Japan"

Mid-range: Marantz (I think, based on model number), 8 ohm, "DS - 54", "Japan", "25W"

2 Subwoofers: Etone, "2876", can't find ohm markings anywhere
Crossover: 8 ohm
Dimensions (h/w/d): 1000 x 415 x 275
Weight: 35kg / speaker
Cabinet: 17mm chipboard, 8-10 mm felt throughout entire inside of cabinet, minimal bracing (see attachment)
 
The tweeters are wired in parallel, as are the subwoofers.
The tweeters in both speakers are blown.  I get no sound out of them and all 4 of them record a 0.L reading on my multimeter.
 
Here are my questions:
 
1. Could these have been built by Peterson Speaker Laboratories or a company of the like or do they look like home built speakers?
2. Any idea how old are these speakers likely to be?
3. If they're old, should I replace the tweeters with the same kind to maintain its integrity as a vintage speaker or just go new?
4. The first tweeter shows 15 ohms.  Is that right? I've never seen 15 before.
5. If the tweeters are 15 ohms and 8 ohms, can the 5.21 ohms circuit be fed into the crossover safely?  I'm guessing so but I wanted to be sure.
 
 
Thanks in advance.
 
 
Dan.
 
 
The second last image is taken from the mid-range opening.  It's hard to see but it shows the two subs and a brace in between.
The last image is of one of the subwoofers.

post-148854-0-56676100-1413714910_thumb.

post-148854-0-58315500-1413714928_thumb.

post-148854-0-39789900-1413714956_thumb.

post-148854-0-61612100-1413715032_thumb.

post-148854-0-38787700-1413715071_thumb.

post-148854-0-71747900-1413715232_thumb.

post-148854-0-73761900-1413715306_thumb.

Edited by dansab
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1. Could these have been built by Peterson Speaker Laboratories or a company of the like or do they look like home built speakers?

 

I have no idea by who. But personally I'd say they are 'factory' made.

 

2. Any idea how old are these speakers likely to be?

 

I'm only guessing, but 70's or 80's maybe. --> EDIT, I'm guessing the "87 - 5" on the tweeter means 5th month 1987.

 

3. If they're old, should I replace the tweeters with the same kind to maintain its integrity as a vintage speaker or just go new?

 

Ahhhhhhh replacing the tweeter will be a crap shoot and will very possibly involve some basic crossover tweeks to get it sounding right.

I'm thinking attenuation changes to match levels at least.

 

4. The first tweeter shows 15 ohms. Is that right? I've never seen 15 before.

 

yup. could be anywhere from 0.5 ohms to 20 ohms and even higher depending on type of driver.

A lot of JBL, Altec Lansing, Warfdale, Klipsch, etc speakers are (were) 16 ohm.

 

5. If the tweeters are 15 ohms and 8 ohms, can the 5.21 ohms circuit be fed into the crossover safely? I'm guessing so but I wanted to be sure.

 

Well, thats how it was wired isn't it ?

the crossover is there to split frequencies, and also 'correct' the load seen by the amplifier.

 

 

But, I'm sure someone will be along shortly to debunk me and post something more accurate, factual, and informative :D

Edited by green wagon
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I thought I had posted this, but apparently not...

 

The Etone woofers probably have their impedance stamped as a number between the terminals, 4, 8 or 16 ohms. I am guessing if the crossover is labeled "8 ohms" then there will be two 16 ohm Etones in parallel.

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The other metal dome tweeters look like something I would not like the sound of LOL.

 

If you measure the diameter of the cutout hole behind them in the baffle and the dimension between the fixing screws, I might be able to suggest something to replace them.

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Hi Dan

It looks to me like you have come across some reasonable speakers ,assembled in Australia ,probably in the 80's. Using some Australian parts ,Etone woofers and Magnavox  tweeters . Not a great deal of value in them so just go straight to new replacement parts. Take your failed tweeters to jaycar ,there items will be inline with the value of the speakers ,and ask them to suggest replacements ,no guarantee old/ second hand parts on ebay will be any good or actually work. I note the Maganavox you are bidding on are being sold as is, with no warranty and untested, cancel your bid as even it this point with postage they will be $30. 

The speakers ,when fixed up,will probably sound more than ok and satisfy your needs until you feel the need to upgrade some time in the future ,as is likely when you gain more knowledge from this site.

Your refurbishment will be a great way to learn at not a big cost.  Go for it and keep us posted with how you get on.

Edited by EVcali
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Zaphod

Surely you can come up with some more useful advice to some one on only their second post ,posting in the Beginners section.

 

Possibly. It is important to realise that these are not good speakers. There is a great deal wrong with the design. If budget is very tight, then just use them, until more funds become available. I don't see any value in spending more money on a flawed design. Just my opinion. Sadly, I am rather well known for my brutal honesty. 

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Appreciate the "possibly" and would not want not want your opinion to be any thing other than honest. perhaps the brutal can come later when Dan has made a few more posts. IMO  Likely expenditure should be low and justifiable given the learning opportunity.    

Edited by EVcali
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A current bid of $15 for a pair of sight unseen drop-in replacements for the Magnavox is good value. Feedback on the seller's past speaker sales is fine so the purchase is a probably a low risk.

 

The Magnavox tweeters would not have enough sensitivity on there own and were probably added because the silver ones didn't get to 20 kHz. The same eBayer has some Philips tweeters that might be a drop in replacement: http://www.ebay.com.au/itm/Philips-tweeters-pair-/141443843659?pt=AU_Electronics_Vintage_Electronics&hash=item20eeb5c64b

 

Or buy something like this: http://www.wagneronline.com.au/dt40/dome-tweeter-metal/tweeter/9-90909-9xx0-usersearch/1-3077/2-6996/pd/

 

Cheap enough to get some most likely high efficiency speakers going again for the shed / parties.

Edited by Guest
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