Skating rink speakers... VOTT?

[janikphoto]

Diaphragm... is it aftermarket? How can I tell?

 

[janikphoto]

All apart...

 

[janikphoto]

I found the source for the harsh sound. The dome is separating from the surround. Can you see the space when I press on it? What adhesive should I use? I'm tempted to use Aleene's on it.

 

[elitopus]

Thats an Altec symbiotik. I would order a new pair of aluminum phragms from GPA. Or send the drivers in for a remag and new diaphragms

 

[janikphoto]

It looks like Simply Speakers offers a diaphragm, as well. One pair is going in a store, and precision sound isn't necessary... just good sound. Another pair is going to the guy who bought these, and he cranks the hell out of everything he owns! I'd want some really durable diaphragms for him, or maybe even put some different drivers on his horns? The pair I'm keeping will stay as original as possible, and the pair they'll sell off will stay original for best resale price.

Soooo, if I do switch out drivers on one pair, what's a reasonably priced replacement that can take some abuse?

 

[bowtie427ss]

The only diaphragms i'm aware of that are worth your time other than proper altecs are Radian, and there is marginal savings if any.

The few import diaphragms i've had experience with are truly awful.
.
If you want them to come close to their potential, there's no way around the right parts.

The best economic alternative i have heard is to jack the XO up to 1.2-1.5K and run with an eminence PSD-2002.

 

[elitopus]

The Radian phragms are good but they are more rolled off than the GPA's. I think they handle more power though. Probably a good compromise for power handling and HF extension

 

[bowtie427ss]

The Radian phragms are good but they are more rolled off than the GPA's. I think they handle more power though. Probably a good compromise for power handling and HF extension

As are GPA 26420 Pascalites.

 

[Sam Cogley]

If you're not worried about ultimate power handling, get the GPA diaphragms, ditch those black loading caps (you'll need shorter screws, head over to ACE Hardware), and enjoy. The loading caps are potentially causing at least a bit of your harsh sound.

Altec never did get that Symbiotik diaphragm to work quite right. Renkus finally figured it out at his son's company.

 

[elitopus]

And the pascalites are cheaper than the Radians too.

+1 on what Sam said.
HD (and probably Ace) sells some #6 brass or SS screws. You want a screw that wont get sucked towards the gap and destroy your diaphragm. Ask me how I know about that

 

[Sam Cogley]

As an addendum to the "ditch the loading cap" advice, make sure you've got a heavy chunk of felt glued to the back of the big rear cover.

That reminds me, I still need to get rear covers for my 902s. They're from the "we're being really cheap" era, and only have loading caps over the diaphragms - no full covers.

 

[bowtie427ss]

Altec never did get that Symbiotik diaphragm to work quite right. Renkus finally figured it out at his son's company.

I wish i could remember the fella's name, used to post on the Altec board, he was partner in development with JRenkus and helped him develop the "tri-laminate" process by which the Renkus and Emilar diaphragms were made. He had a bunch of Emilar stuff leftover, original boxes and items like that, no hardware. I lost his contact info in a HD crash long ago.

 

[Tom Brennan]

As for Radians, old Max Potter sold me a pair of JBL 2420s with Radians and had graphs he ran showing more extended highs from the Radians than original JBL aluminums. They might be a good way to go for guys who don't like JBL titanium diaphragms, assuming JBL no longer makes aluminum ones, as was once true.

 

[elitopus]

As for Radians, old Max Potter sold me a pair of JBL 2420s with Radians and had graphs he ran showing more extended highs from the Radians than original JBL aluminums. They might be a good way to go for guys who don't like JBL titanium diaphragms, assuming JBL no longer makes aluminum ones, as was once true.

I think the Radian diaphragms for JBL are much better than the ones they made for Altec drivers. I have a friend who swears by Radian phragms in JBL 2440/2441 drivers.

The Radians I had in a pair of 808a drivers were better than symbiotiks but still fell short of HF response compared to an Altec/GPA aluminum diaphragm

 

[janikphoto]

Soooo... don't use the black puck and get shorter screws and a chunk of felt, instead? OK.

 

[Sam Cogley]

The felt goes on the back inside of the cover, not over the diaphragm. Just for clarity's sake.

 

[janikphoto]

The felt goes on the back inside of the cover, not over the diaphragm. Just for clarity's sake.

Yup, that's what I figured. Otherwise, the rear soundwave hits that flat metal on the inside of the rear cover. It looks like the pick could be modified, as well. If I bored out the center of it, it would basically act like a spacer.

 

[janikphoto]

So, I had to patch this dustcap...

 

[janikphoto]

Here's the patch, which I'll paint tomorrow.

 

[janikphoto]

Here's another interior shot. It's weird to see what was and wasn't painted... it definitely makes me wonder what the original port configuration was.

Also, I used Aleene's glue on the diaphragm and it's not harsh anymore. However, it's still much weaker than the other horn. I noticed that some of the voice coil had rubbing/scratches on it. I'm guessing it wasn't aligned when it had come partially apart, and that was damage/rubbing I saw. It still plays, but at a much lower volume.