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Multi-Way Conventional loudspeakers with crossovers

Realistic/Optimus Mach Two Tweeter
Realistic/Optimus Mach Two Tweeter
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Old 7th September 2008, 12:18 AM   #1
nevdale is offline nevdale  United Kingdom
diyAudio Member
Join Date: Sep 2008
Question Realistic/Optimus Mach Two Tweeter


I have recently come into possession of a pair of Realistic Mach Two speakers, which I have wired up to an old amp that probably doesn't do them any justice. They aren't in great condition, as they have been lugged around and abused at student parties for the last few years. However, they work, and still sound lovely!

Unfortunately, the tweeter in one of the speakers has completely died. It looks like the coil (?) has come unstuck and is now hiding inside the magnet. I hope that makes sense. Also, the wires connected to the coil are broken and with my shaky hands and from reading other peoples' posts on the subject I can guarantee I'm not going to be able to solder these!

So, I want to buy a new tweeter... however, it looks like these are going to be almost impossible to get hold of in the UK. Any advice on replacements for this tweeter in particular, or tweeters in general that might fit the bill would make me very happy! I will attach two photos shortly, one of the plastic tweeter cover and one of the back of the tweeter (text reads "Tweeter / SH-21 8 Ohms / JAPAN / 66391")

I believe the mach twos employ a passive crossover. How much does this affect my choice of speaker?

current tweeter: 8ohm
cabinet rating: 100w max
However, as I understand it, tweeters are a little more complicated than this...

I've seen this one, would it fit the specifications?

Thanks a lot to anybody who has any advice
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Old 8th September 2008, 09:55 AM   #2
sreten is offline sreten  United Kingdom
Join Date: Nov 2003
Location: Brighton UK

Do not fit that piezo tweeter without modifying the crossover.
It appears to have a slot tweeter. A pro type tweeter should work.


Something like :




Might be better if it is sensitive enough ....

Around 7.50 each ... you would need a pair ...

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Old 9th September 2008, 03:11 PM   #3
nevdale is offline nevdale  United Kingdom
diyAudio Member
Join Date: Sep 2008
That's really a fantastic help. I spent hours looking at different sites selling speakers, but didn't come across those.

You mentioned the crossover regarding my first link. Just to double check, if I purchase a pair of either of those models would I be able to fit them and play, or would I need to fiddle with the crossover?

Thanks for your help. Please let me know if I'm not being specific enough!
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Old 9th September 2008, 04:14 PM   #4
sreten is offline sreten  United Kingdom
Join Date: Nov 2003
Location: Brighton UK

The basic answer is yes because the speaker has level controls.

If you have a multimeter you can check the resistance of the good
slot tweeter, ~ 3R = 4 ohm and ~ 6R = 8 ohm impedance. The
latter is the most likely and then those drivers should be fine.

It is difficult to hand wave and say what would be best .....

If you want a better manafacturer :

Eminence : http://www.ukdj.com/index.asp?PageAc...D&ProdID=19662

Fane : http://cgi.ebay.co.uk/FANE-J40R-TWEE...3286.m20.l1116

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