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You can now salvage un-salvageable OLA's


Carlspeak

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  • 1 year later...

Hi Ronald, when I was looking to rebuild some OLA’s, I wound up simply buying two pairs of woofers (and 3 pairs of tweeters) on eBay.  I think that’s your best bet.  One pair of woofers needed new surrounds (which I replaced, a reasonably easy, but not trivial exercise) and one pair basically was “good to go”.  (There was a price difference…)  If you go the route of replacing the surrounds, you need to make sure to purchase the correct surrounds.  Reading a few of the strings here will turn up the correct replacement, I can’t quite remember from whom I purchased, so I’d also have to look to refresh my memory.

There are two types of woofer that will serve as drop in replacements for the OLA: (1) the actual “Masonite” woofers from the OLA, or (2) the steel face woofers from the “New Large Advent.”  They’re absolutely interchangeable and I suspect that the steel face woofers are actually easier to obtain.  The original ones have a Masonite face, a brown, 2” wide ring of Masonite on the front face of the woofer.  The NLA woofers just have a steel face.  I am not aware of any other woofers that are completely suitable.

Searching for “NLA woofer” or “OLA woofer” on eBay will probably bring them up.  You may need to be patient for the items to actually come up for sale, but when I was looking a couple years ago I was able to purchase the two pairs fairly quickly.

Good luck!

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  • 2 years later...

I know this is an old thread, and also that the OP has sadly passed away, but can anyone post a circuit diagram of the crossover that Carl designed? I bought those tweeters way back when, while in the process of moving, and have just gotten around to setting up my HiFi gear. I don't see where the 3 ohm resistor (specs?) goes, and does the red wire (woofer?) attach directly to the pos. terminal? I'd really like to try this since already have the cabinets braced.

Thanks

post-100237-0-96660100-1432507253.jpg

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Anybody care to take a shot at a diagram? Its a shame that Carl spent his time designing this, but it wasn't fully explained. I'm not an electronics guy, and don't want to short anything out by guessing.

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On 3/24/2024 at 3:22 PM, RacerX said:

Anybody care to take a shot at a diagram? Its a shame that Carl spent his time designing this, but it wasn't fully explained. I'm not an electronics guy, and don't want to short anything out by guessing.

-The woofer's + lead (red) and the tweeter's 20uf capacitor should connect to the cabinet's + input terminal.

-The two black leads connect the cabinet's - input terminal to the - sides of the tweeter and the woofer respectively.

-The 3 ohm resistor (not shown) is connected in series via the yellow (+) tweeter wire emerging from the junction of the cap and .05mh coil. The resistor can be placed anywhere before the tweeter's + side along that yellow wire.

-As shown in the photo, the .05mh coil is also connected to the cabinet's - input terminal along with the 2 black - wires. It is in parallel with the tweeter, which means it is connected to both sides of the tweeter circuit (- and +).

Carl was using a new Advent replacement woofer with no inductor. The only crossover components would be in the tweeter circuit (ie the 20uf cap, .05mh parallel coil, and 3 ohm resistor).

Roy

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Thanks so much for replying. I bought the components with the speakers, and I hope they are the right ones.

 

As far as the inductor goes, I should probably try it with, and without. Would you know the specs for one to try?

IMG_20240325_181007975.jpg

IMG_20240325_181016476.jpg

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5 hours ago, RacerX said:

Thanks so much for replying. I bought the components with the speakers, and I hope they are the right ones.

 

As far as the inductor goes, I should probably try it with, and without. Would you know the specs for one to try?

I'm very glad you asked that question. I typed in the wrong value (I just corrected it). It is .5mh, not .05mh. Your photo shows that you have the right components.

The coil is absolutely necessary! It is not only important for the proper response, but to protect the tweeter. 20uf is a very large capacitor value to use without it.

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23 hours ago, RoyC said:

Carl was using a new Advent replacement woofer with no inductor. The only crossover components would be in the tweeter circuit (ie the 20uf cap, .05mh parallel coil, and 3 ohm resistor).

Ok, This sentence I didn't quite understand. I thought you meant that since I was using the original woofers that I would also need an inductor in series with that. My mistake.

 

Does this diagram look right?

IMG_20240326_161523168.jpg

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11 hours ago, RacerX said:

Ok, This sentence I didn't quite understand. I thought you meant that since I was using the original woofers that I would also need an inductor in series with that. My mistake.

 

Does this diagram look right?

Your drawing looks good.

Based on Carl's description of the response differences/similarities between the new and original woofer it should work as he described.

Roy

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