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Optimus 1B loudspeakers

I have a set of Optimus 1Bs. They are a nice speaker. Not quite as nice as the 5B, but not for off.

I have personally never seen a speaker shorted.
I have seen them fail open circuit.

The woofer in the 1B is particularly nice.

Mine has the cast aluminum basket vs. the stamped steel shown in the ebay ad that Gnensen links to.

Are your crossovers right?
You can probably find some images online to help with that assessment.

Can you short a battery across the woofer terminals and get the cones to move?

Do they move if you gently push on them?
 
Gazdatronik said:
And a note on the tweeters, get only factory used good replacements. They are 16 ohm and cross over at 350 hz, so there are basically no new tweeters that are bolt in replacements.
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I did see the that the two tweeters are 16ohm in parallel. I've been reading various reviews and threads that state the tweeter(s) are the weak part of the speaker, with recommendations to replace with one with a newer 8 ohm and just the other in to fill hole.
 
rkgren1 said:
I have a set of Optimus 1Bs. They are a nice speaker. Not quite as nice as the 5B, but not for off.

I have personally never seen a speaker shorted.
I have seen them fail open circuit.

The woofer in the 1B is particularly nice.

Mine has the cast aluminum basket vs. the stamped steel shown in the ebay ad that Gnensen links to.

Are your crossovers right?
You can probably find some images online to help with that assessment.

Can you short a battery across the woofer terminals and get the cones to move?

Do they move if you gently push on them?
Click to expand...

I haven't accessed the crossovers yet, I removed the woofer to test with a multi-meter (it read"00"). I didn't try the 9-volt battery, I saw that once and I'm willing to try it. The cones do move manually. How could I test between short and open circuit?
 
If you connected your 1B's to an amp and got NO sound from either, that implies the woofer and both tweeters (or a tweeter filter series component) in each cabinet are open. Here's the crossover schematic:

7B_1B_xover.png

There is no low pass filter for the woofer. It runs free.

With tweeter level switch at "High" only the 15uF capacitor is in series with the tweeters. If that cap is open no sound will come from the tweeters. Tweeters themselves can be measured with a meter as easily as woofers to determine state of the voice coils.

Seriously doubt there are voice coil replacement kits for these speakers. Genuine speaker components really do come up on ebay regularly, and would very likely run much less than the $hundreds of your proposed budget.

Search for both Optimus-1B and Nova-7B, which use identical drivers and crossovers. But don't confuse these with Optimus-1 or Nova-7, which are different from the B variants and even different from each other.
 
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Stuart Pedaso said:
If you connected your 1B's to an amp and got NO sound from either, that implies the woofer and both tweeters (or a tweeter filter series component) in each cabinet are open. Here's the crossover schematic:

View attachment 1177008

There is no low pass filter for the woofer. It runs free.

With tweeter level switch at "High" only the 15uF capacitor is in series with the tweeters. If that cap is open no sound will come from the tweeters. Tweeters themselves can be measured with a meter as easily as woofers to determine state of the voice coils.

Seriously doubt there are voice coil replacement kits for these speakers. Genuine speaker components really do come up on ebay regularly, and would very likely run much less than the $hundreds of your proposed budget.

Search for both Optimus-1B and Nova-7B, which use identical drivers and crossovers. But don't confuse these with Optimus-1 or Nova-7, which are different from the B variants and even different from each other.
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Thank you, I'll start looking.
 
A short in the RCA plug may give the symptoms described, so would a short across that 15 uF capacitor.

I could not be something so fundamental as a speaker switch set to OFF or a problem of contact between speaker wires and terminals could it?
I have made worse mistakes than that on good days.
 
Flip4tim said:
I haven't accessed the crossovers yet, I removed the woofer to test with a multi-meter (it read"00"). I didn't try the 9-volt battery, I saw that once and I'm willing to try it. The cones do move manually. How could I test between short and open circuit?
Click to expand...

I would be interested to see what you get if you remove and test the tweeters with an ohm meter.
 
rkgren1 said:
A short in the RCA plug may give the symptoms described, so would a short across that 15 uF capacitor.

I could not be something so fundamental as a speaker switch set to OFF or a problem of contact between speaker wires and terminals could it?
I have made worse mistakes than that on good days.
Click to expand...

I wish it was a simple mistake, but I think it’s more than that at this point.
 
waggs098 said:
Also ill ask again what does your meter read when it's on the ohm setting and the leads not hooked to anything.
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My Greenly Multimeter set at 200 ohms reads a "1" on the far left of the digital display when not hooked to anything. I removed all 6 drivers (2 woofers and 4 tweeters) to retest. On the first Woofer, the meter went to "00" but then the reading started bouncing all over. I noticed that this occurred as I was inadvertently moving the cone. When I placed the driver on a more stable surface the multimeter gave NO reading (stayed at "1" on far left) This is the same reading "1" I took on all 6 drivers. My initial reporting of "00" may have been affected by my senior memory of the meter giving me no reading :confused:, or I moved the cone and didn't realize it.
The meter does give me a reading of 6.2 on my working Onkyo speaker. All cones appear in good shape and move freely.
 
Try wiggling the tinsel leads going to the woofer see if you get a connection , iv seen open tinsel wire on rat shack speakers in the past , moving it around would get intermidit connection , you could allso try measuring right where wire enters the cone
 
Flip4tim said:
My Greenly Multimeter set at 200 ohms reads a "1" on the far left of the digital display when not hooked to anything. I removed all 6 drivers (2 woofers and 4 tweeters) to retest. On the first Woofer, the meter went to "00" but then the reading started bouncing all over. I noticed that this occurred as I was inadvertently moving the cone. When I placed the driver on a more stable surface the multimeter gave NO reading (stayed at "1" on far left) This is the same reading "1" I took on all 6 drivers. My initial reporting of "00" may have been affected by my senior memory of the meter giving me no reading :confused:, or I moved the cone and didn't realize it.
The meter does give me a reading of 6.2 on my working Onkyo speaker. All cones appear in good shape and move freely.
Click to expand...

Well on that note it sounds like all drivers are toast. That's really weird that all are bad. Wonder if someone's amp failed miserably and sent high dc to both speakers.
 
Yeah, all drivers open is whats got everyone here questions things. But I guess it happens.
There are some 1b's here locally on CList for $100. I don't think I would pay that.
 
Gnesen said:
Me neither. They tend to go for $40-$70 in my area. Still, they're a very respectable speaker -- I was certainly surprised when I heard my first pair.
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The cabinets are in really good shape, would outfitting them with new drivers make sense, or just move on? I looked at replacing the drivers with ones from Ebay as suggested by some, but the price with shipping may exceed the value of the project.
 
Flip4tim said:
The cabinets are in really good shape, would outfitting them with new drivers make sense, or just move on? I looked at replacing the drivers with ones from Ebay as suggested by some, but the price with shipping may exceed the value of the project.
Click to expand...

I guess it depends. If you like the looks of the cabinets and would like to learn more about speaker building, you could use them as the basis of a project. In particular, those cabs seem ripe for an 'Econowave' speaker. Alternatively, if you just want a nice sounding pair of speakers, I would suggest selling your Optimus-1B cabs and taking your $400 budget to buy something modern, like the aforementioned Elac UniFi UB5s. I am a big fan of both vintage and new speakers, but in my experience most new speakers of repute (read: not super cheap) are just plain better performers overall. With new speakers you also don't need to worry about past abuse or doing repairs (at least until you've had them for a long time). Of course, there are certainly some exceptions, like the 'vintage' Yamaha NS-670s that I picked up recently.
 
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Gnesen said:
I guess it depends. If you like the looks of the cabinets and would like to learn more about speaker building, you could use them as the basis of a project. In particular, those cabs seem ripe for an 'Econowave' speaker. Alternatively, if you just want a nice sounding pair of speakers, I would suggest selling your Optimus-1B cabs and taking your $400 budget to buy something modern, like the aforementioned Elac UniFi UB5s. I am a big fan of both vintage and new speakers, but in my experience most new speakers of repute (read: not super cheap) are just plain better performers overall. With new speakers you also don't need to worry about past abuse or doing repairs (at least until you've had them for a long time). Of course, there are certainly some exceptions, like the 'vintage' Yamaha NS-670s that I picked up recently.
Click to expand...
The "Econowave" idea is entertaining. Those Yamaha's are great looking speakers, nice pick up. Was that a craigslist find? I've been watching craigslist and estate sales, like many, hope to find something interesting, as well as, pick up some more albums for the collection. Its been fun enjoying this again with my seven year old. So far he likes Jimi Hendrix the most :rockon:
 
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