Very early Altec 602D

[Dswankey]

Wow, you are a wealth of information, thanks.

Agreed!!!!!!

 

[stevengerard]

Back in the day, the standard was to damp 3 internal sides. That's generally all that's necessary to stop standing waves. Sometimes, port location and arrangement can require a bit more if there are issues with reflections making it out of the port.

Sometimes called a shelf port.

Anything but for an 803/416, unless you're trying to make it a subwoofer. Those woofers really want a port.

A front/back brace from the baffle area between the large rectangular opening and woofer opening would be my first step, followed closely by diagonal reinforcing braces on the sides and back.

Thanks, I'll start with some bracing and see how both sound together as a pair with the 1228 horns

 

[stevengerard]

Got them back together with the Realistic 1228s btjey sound nice. I have only had them on very low volume, not sure if I should run them at low volume for a while or not.

 

[stevengerard]

I was going to look into updating the crossovers but those things are covered in tar. Very nicely I may say and it is spotless in there. I read they are oil based capacitors which “should” have a longer shelf life. Should I dig into that or leave well enough alone.

 

[bowtie427ss]

Should I dig into that or leave well enough alone.

Purely opinion here, most potted Altec networks i usually choose to leave 100% original for the next guy, and scratch build new for my own use. That's gotten a bit costlier in recent years.

Sometimes, things are out of spec and you have to replace them, especially the red wax sealed electrolytics Altec used in the late 60's and 70's. But, those networks are usually un-potted and easier to work on.

 

[loudnoises]

Got them back together with the Realistic 1228s btjey sound nice. I have only had them on very low volume, not sure if I should run them at low volume for a while or not.

I've had old drivers take a few moments to wake up, but it's not a long process.

 

[stevengerard]

Purely opinion here, most potted Altec networks i usually choose to leave 100% original for the next guy, and scratch build new for my own use. That's gotten a bit costlier in recent years.

Sometimes, things are out of spec and you have to replace them, especially the red wax sealed electrolytics Altec used in the late 60's and 70's. But, those networks are usually un-potted and easier to work on.

I was fortunate to run into an Altec engineer at AXPONA today. He said chances are the ones in my cabinet are old enough they are most likely still good but of course no guarantees. He also suggested to try the setup with the top horn location fully open as a port as you never know until you try it. He was looking at my pics of the inside and suggested adding some material to the side that wasn't covered but confirmed what you said, it wasn't necessary but wouldn't hurt and told me if I did add any, don't add much.

 

[MissionX]

I think about half that port may be closer to optimal than all of it. Looks pretty big.

 

[stevengerard]

I think about half that port may be closer to optimal than all of it. Looks pretty big.

Just saw this - that upper port is closed off with only the replacement EV-T35 in there. The port for the bass is below the woofer under that shelf. I did have the woofers rebuilt and took out the 3000H tweeters. Over the winter I will see if I can get them to work