Altec Model 15 project

[Katalyst]

Lucked into a pair of Model 15 Altecs missing the woofers. The original owner said a friend blew the woofers at a party in the 80's.He did not know the woofers could be repaired. I put a pair of Daytons in to check function. Need recommendations for what woofer to find for these jewels. Any guidance would be welcome. Thanks.

 

[turnitdown]

Dimensions of the box?

 

[Katalyst]

External 22 w by 27 h by 15 1/2 d. I think 3/4" thick box walls. The date of manufacture is 12-21-1976. I have a pair of Altec 412c bi-flex in other speakers I could use. Thanks.

 

[turnitdown]

Approximately (roughly) 4.0 cu. ft. A 2235 will get into the 30s in that box. If you re-do the baffle, an LE14 will play even lower...but I'm a JBL homer.

 

[Katalyst]

The data on the crossover says 1700 hz for the tweeter. These are the series one 15's with the plastic horns. Good thing is the recess for the woofer is a standard size. From what I have found the series two had an odd size cut for the woofer. The dc 300-8 woofer is not as efficient as the 15's horn. The 412c's will be a better match to the horns. The dc 300-8 were in the speakers that have the 412c's in them now originally. Thanks for the response.

 

[bowtie427ss]

033785 is the correct woofer, made in house by Altec, and with a rather odd ~13 inch diameter cast aluminum frame. It was used in all model 15's except the very first versions which used a stamped steel frame CTS woofer built to Altec's spec. The same woofer is also used in Santana II and Model 9. They can almost continuously be found on ebay.

Good thing is the recess for the woofer is a standard size.

This makes them early, among the first few hundred out the door. They used the CTS built woofer.

 

[Katalyst]

It was used in all model 15's except the very first versions which used a stamped steel frame CTS woofer built to Altec's spec.

Yes the early version for the ones I have. The serial numbers are 03069 and 01536. The Altec 412c biflex I have are the cast frame. They are designed for mounting from the rear of the baffle. A gasket to allow for the cast nibs by the mounting holes may let me front mount them? Listening to them with the daytons now. I have the mid/tweeter adjustments backed off to compensate as best as possible.

 

[Sam08861]

Lucked into a pair of Model 15 Altecs missing the woofers. The original owner said a friend blew the woofers at a party in the 80's.He did not know the woofers could be repaired. I put a pair of Daytons in to check function. Need recommendations for what woofer to find for these jewels. Any guidance would be welcome. Thanks.

Were the original woofers thrown away? If not, would suggest sending to Great Plains audio or repairing yourself depending on what is wrong with them.

 

[Katalyst]

The original owner pitched them. The damaged woofers happened in the late 1980's. The Altec 412c I have can not be front mounted without modifications. I will start with adding a crossover to the Dayton woofer. Also going to freshen up the existing tweeter circuit. When I happen across some more appropriate woofers I can upgrade then. Thanks for the responses.

 

[Katalyst]

Ordered the capacitors from Madisound today. Sent a message to Great Plains for possible woofers. GPA Model 3124 Low-Frequency Loudspeaker. The Daytons play to 25 hz but are not as efficient . I will know more when the Altec crossovers are refreshed. I will use the low section of the Ewave crossover for the DC300-8 for now.

 

[Katalyst]

Diaphragm on one of the tweeters died. Reads open. Will not use again till capacitors arrive. Removed end cap and pulled out the offending part. I will hold off on getting any more parts for now. When the capacitors arrive I will complete the crossover and test/listen to the surviving one. Here are some pictures of where the project stands as of now. I believe these are the light elements mentioned in other threads.

 

[bowtie427ss]

Removed end cap and pulled out the offending part.

DO NOT Discard!

Let's see a good pic of the front side where the flexible leads pass through the mounting hub and reach down to pass through the diaphragm itself to the voice coil connections.

 

[Katalyst]

I will not discard it. I have heard member dgwojo has had some luck at repairing them. I plan on contacting him.

 

[setup1]

+1 do not discard that 23744, I've had some success mending broken leads in "open" diaphragms but it's a delicate operation.

If your carpentry skills are up to changing the front baffle on the Altec 15 cabinet, then perhaps you can use your 412 Bi-Flex.

Here's an example of an altered Altec 15 cabinet with the 32 horn mounted on top (hope the link works): http://www.dcaudiodiy.com/phpBB3/viewtopic.php?f=4&t=765&p=7841#p7841 -

But there's also enough space to keep the 32 horn mounted internally.

Good luck!

 

[Katalyst]

I sent a pm to dgwojo inquiring about having him attempt a repair. The crossover components are scheduled for delivery tomorrow. Over the weekend time permitting I will rebuild them. Thanks to all for the advice on these.

 

[Katalyst]

Has anyone tried this driver https://www.parts-express.com/selenium-d220ti-omf-8-1-titanium-horn-driver-8-ohm-2-3-bolt--299-2321 on the bent horn?

 

[Katalyst]

First crossover completed. Crude but functional. Added the woofer section for the Dayton. Copied a schematic and added the woofer mod to it. Used thin plywood for the adapter to the oem crossover.

 

[Katalyst]

Second crossover completed. There are some people that remove the bug screens . This is why they are there.

 

[Katalyst]

Update on the project. Diaphragms ordered and on their way. The frame of the Altec 412c has casting ribs that keep it from dropping in. I notched the opening to fit it. A lazy Susan is nice for laying the sealing tape.Some pictures of the progress.

 

[setup1]

Looking good!