Realistic Optimus 5Bs or Infinity ES-103s?

BostonDave

BostonDave

Lunatic Member
I have a chance to pick up a set of either of these for about the same price. Any opinions on which is better before I go through the bother of trying to audition them to decide by ear? Are they even close or way off?
 
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I should mention that the passive radiators on the Infinitys are both missing which might cost more than the speakers are going for to replace. The Realistics appear to be all there though.
 
I haven't heard the Ifinitys, but my 5B's compare very well to my Mission 770S's and Paradigm Titans. Hard to choose a favourite. The 5B's also have stood the test of time, still have their original surrounds.
Usubstantiated rumour: the 5B's were made by KLH.. or Kef.. or have their components in them.
 
I haven't been able to find the 5B's in any old Radio Shack catalogues. I found the 5's which seem to have been in production from about 1970 to 1974. I'm assuming the 5B's must be newer. Does anyone know the approx vintage?

The ones that I'm looking at appear to be in mint condition.
 
Hey thanks. Looks like 1976-78 for the 5Bs.

I found out the seller is the same guy for both sets which will simplify an audition.
 
Here's the catalog it appeared in. The link is courtesy of Wolverine :thmbsp:

I like my pair but have been considering replacing the high frequency driver.
 
I have a few pairs of the 5b's and they are respectable speakers. I also have an older pair of Infinity Qa. Infinity's tweeter are quite amazing. The 103 that you are comparing the 5bs to are more sophisticated and were more expensive. Tehy don't have the Qa emit tweeters but the polycell might be better than the 5b components

1 Polypropylene Polycell Dome Tweeter
1 Polypropylene Polycell Dome Midrange
1 - 10" (25.4 cm) Woofer
1 - 12" (30.5 cm) Passive Radiator
Dimensions: 38"H x 18"W"
Cabinet Not Sold
Grille NLA
Crossover NLA
Control Pot. #145-0103
Logo #716-0347
Introduced in 1983
Discontinued 1995
Original Retail Price: $619.00/pair

If all of the other components work (other than the passive radiator) the infinity might be a better deal. the 5b were 150 to 200 a pair when new.

infinity speakers, however, generally require power, good clean power and LOTS of it. Do you have an (good vintage) amplifier that can deliver 80 or more watts of power?

So, no clear answer here!
 
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I would give the nod to the Optimus'. Although vintage, the ES-103's are not one of the more sought-after models. They are a budget speaker that uses a Polycell tweeter instead of the more desirable EMIT tweeter; have thin cabinet walls with less bracing; and IIRC are finished in vinyl instead of wood veneer. The ES-103's are also one of the few Infinity's to use a passive radiator, so they are not the power hogs that most other Infinity's of this era are/were.
 
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Optimus 5B is an excellent sounding speaker. Sorry I can't comment on the Infinifty ES-103 as I've never heard it, but I've taken 5B's apart and listened to them and IMHO they sound great and are quite well built. The surrounds don't rot out, the woofers are quite robust and have large voice coils and magnets, and the tweeter/mid drivers are pretty hard to kill and not too hard to find. Two of the high frequency drivers are used for midrange and one is used as the tweeter. I like the way they sound, the way they look and the way they're built.
 
I'll probably go and audition them sometime this weekend. For practical purposes the 5B's are more easily stackable with other speakers - which is surely what the situation will be if they're competitive with the other speakers in my current 'production' system quality wise.

The seller told me that there is some foam placed where the passives used to be in the Infinitys and it makes the cabinet airtight and looks better than the holes (from the picture it actually doesn't look like the passives are even missing).

There was quite a price difference when these 2 sets were new with the Infinity's being over 4 times more expensive (and also maybe 10-20 years newer). Hopefully a listening audition will be easily decisive one way of the other.
 
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Quick update: I'm holding out a little longer on these as a pair of Dynaco A-25s came up locally for what seems to be a fairly decent price (although twice what the asking on the 5B's is). I'm only looking for one pair of additional speakers now so I'll have to wait and see on the A25s first.
 
I've never owned a pair of Infinitys, but was very impressed with the quality of sound that I got out of the the Optimus 5 B's after recapping them. I gave my pair to my Dad (mated with a Nikko receiver) and I swear every time I go over there and listen to them they sound better than the last time. Damn, should have passed on to him my spair set of titans instead! :D
 
Picked up the A25s today. Pretty pleased with them so far (and I haven't even run any tube or vinyl through them yet). The 5B's are still for sale but my wife's actually yelling at me to the tune of "where did those ugly things come from, and where are the ones they replaced going to go!!!" right now as I'm typing this :) so the 5Bs are probably on hold for a little while. How she can speak that way about such things of beauty is beyond me.
 
So, I know about the wife being displeased with an audio hobby. Strangely enough, my wife came around to accepting my obsession. It seems that she was talking to her sister who noted that her husband's only hobby was watching TV. My wife decided that crazy was better than sedated.
 
rmeade said:
So, I know about the wife being displeased with an audio hobby. Strangely enough, my wife came around to accepting my obsession. It seems that she was talking to her sister who noted that her husband's only hobby was watching TV. My wife decided that crazy was better than sedated.
Click to expand...

I'll have to try that one out and see how it goes over (unfortunately her best friends husband's hobby is currenly being overly obsessive about his DIY home renovation projects so I look like the lazy one). I'm either going to have to knock him off (or light bulb just lit up... get him hooked on vintage audio himself!!!) I may have to put together a nice little vintage gear christmas present for him. His wife is going to hate me too...
 
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