Altec 511 question

[jaymanaa]

I made an interesting discovery today. I've been using some 511Bs with 902-8B drivers for a couple months with what I thought were pretty good results. The only complaint I had was that every now and then, they would sound a little distorted (which seemed strange cause I'm running under 10 watts). I ASSumed that the distortion was coming from the amplifiers, so I began rolling tubes like nobodys business. Some seemd to help a bit, but evry now and then I would hear a little something ugly. I started to think maybe the horns were the culprit and needed some maintenance. I asked about it over at Lansing Heritage, but didn't get any replys. I finally decided to just take them apart and found the damndest thing, a little (very fine mesh) screen covering the outlet of the driver. They were pretty filthy with lint and dust so I removed them and washed the insides of the horns real good, while I had the drivers off. Not only is the distortion gone, but the horns sound way mo better. The odd thing to me is, now I have turned the HF L-Pad up:scratch2: I would have thought I would have had to turn it down, but maybe since the horns are not objectional now, I am enjoying more of them. I just thought I'd post this in case there are any other "horn" newbies around. Seems like horns are hard to get real world experience and advice on. Jay

 

[Paul C]

I have heard of some guys removing the "bug screens". Seems they can corrode and plug up. Others say it makes no difference.

 

[jaymanaa]

Funny you say "bug screens". That was the only practical use I could see for them, and even mentioned to the wife that they were probably for wasps, if the horns were used outside. Mine had quite a bit of what looked to be very fine "metal dust", which was attracted by the magnetism I guess. They sure do sound better, allthough cleaning the screens could have netted the same result. I just didn't see any need for them on an "inside" application. Jay

 

[Tom Brennan]

"Mine had quite a bit of what looked to be very fine "metal dust", which was attracted by the magnetism I guess."

That's one of the reasons the bug screens are there, you don't want that gunk in the gap. And they do keep bugs out, a friend was going to remove the screens from his JBL 2420s until he noticed an Asian ladybug marching up the Edgar saladbowl one day. Those bugs infest Illinois and work their way through windowseals and into the house.

Good to keep the screens clean of course. As for outright removing them, well I've owned scads of Altec and JBL compression drivers some with screens and some without and I never heard a difference I think had to do with the screens.

Regards

 

[bowtie427ss]

I'd have to second TB's point, diaphrams are very delicate assemblies and would not take well to removal of any foriegn debris. Keep your screens in place, the same guys that designed that horn and driver specified those screens for a reason.

 

[dgwojo]

Another thing to watch for on the later 802/808/902/908/909 is loose tangerine phase plugs, they can damage the diaphragm if they come loose, use 5 minute epoxy, superglues tend to eat plastics, Dave.

BTW, some 604-8G's, all 604-8H, 604-8K's can be plagued by this issue too;

 

[bowtie427ss]

Great pics Dave!

Does the phase plug naturally want to seat itself in the proper position, or is there a secret to keeping it centered and from interfering with the coil gap?

 

[Tom Brennan]

SS--The thing just sits right in there as neat as you please, centers itself.

I've used superglue to fix them, no apparent problem.

 

[dgwojo]

Great pics Dave!

Does the phase plug naturally want to seat itself in the proper position, or is there a secret to keeping it centered and from interfering with the coil gap?

As Tom said, it tends to center itself while seating and holding it down for the glue to set. If you do one of these, make sure you use the glue sparingly and remove as much of the old residue as possible, too much glue clogs the phase plug slits. Some Super Glues are plastic safe others eat the plastic over time, plus I like the 5 minute set time for centering!! The old drivers aren't plagued by this problem, here's a pair I made up from parts last year for the Klipsch/Altec project, Bill at GPA recharged the alnicos and those are his newly mfg'd 34647 aluminum 8 ohm tangential suspension diaphragms, the acoustic loading caps were retained as these speakers are used in a hall at higher volumes, Dave. :yes:

 

[Tom Brennan]

Nice terminal posts. Parts Express?

 

[dgwojo]

Nice terminal posts. Parts Express?

Tom, I think I bought them from MCM, Dave. :yes:

50-590

 

[bowtie427ss]

Thanks guys, and understood about the sparing use of glue. I have a pair of 808-8B awaiting the "transformation" and this has me thinking it'd be a good idea to give those phase plugs a bit of a nudge to ensure they're glued fast.

Would they be removed during a recharge at GPA?

I appreciate the input.

 

[dgwojo]

Would they be removed during a recharge at GPA?

No, Bill doesn't have to remove them, I heard he's able to install plastic tangerines in the metal phase plug drivers now, Dave. :scratch2:

 

[Billfort]

I made an interesting discovery today. I've been using some 511Bs with 902-8B drivers for a couple months with what I thought were pretty good results. The only complaint I had was that every now and then, they would sound a little distorted (which seemed strange cause I'm running under 10 watts). I ASSumed that the distortion was coming from the amplifiers, so I began rolling tubes like nobodys business. Some seemd to help a bit, but evry now and then I would hear a little something ugly. I started to think maybe the horns were the culprit and needed some maintenance. I asked about it over at Lansing Heritage, but didn't get any replys. I finally decided to just take them apart and found the damndest thing, a little (very fine mesh) screen covering the outlet of the driver. They were pretty filthy with lint and dust so I removed them and washed the insides of the horns real good, while I had the drivers off. Not only is the distortion gone, but the horns sound way mo better. The odd thing to me is, now I have turned the HF L-Pad up:scratch2: I would have thought I would have had to turn it down, but maybe since the horns are not objectional now, I am enjoying more of them. I just thought I'd post this in case there are any other "horn" newbies around. Seems like horns are hard to get real world experience and advice on. Jay

Interesting Jay - I wonder how much of the change you heard is the cleaning and how much is removing the screen?

I have a pair of 902's (that need the phase plugs re-glued) and 288's that I'll be trying with and without the screens as I've heard opinions for and against removal - a good place to decide by listening for yourself if you are ok with the insect risk.

 

[dgwojo]

I leave my screens in for two resons on the 802/808 drivers, I hate crawling bugs and removing the screen can cause the throats to resonate as it leaves play in the space taken up by the screen (the throat moves up and down without it). :nono:

Here's a nudie of 802/808 nontangerine drivers, I had to buy a throat from Bill at GPA, once taken apart the magnet is discharged for the most part and has to be recharged to be used again so don't do this at home!!

 

[jaymanaa]

Interesting Jay - I wonder how much of the change you heard is the cleaning and how much is removing the screen?

I have a pair of 902's (that need the phase plugs re-glued) and 288's that I'll be trying with and without the screens as I've heard opinions for and against removal - a good place to decide by listening for yourself if you are ok with the insect risk.

Well, it's for sure that I won't be putting "these" sreens back in. They got pretty bugered up on removal. I don't think I have a huge insect risk at present (winter), but may get some new screens and gaskets to try, just to see if I can hear a difference. I was remembering a thread in DIY not too long ago about speaker grill cloth, and how it could effect sound. If I'm remebering correctly, the consensus was that HF were more hampered by the cloth than LF. This made me wonder about the potential for improvement by removing the rather dense screens. However, it's quite possible that the improvement I noticed was largely in part to getting rid of the crud as well. Wichever it is, I'm sure liking the end result. I was shopping for super tweeters, but now I'm not so sure I need them. Jay

 

[doucanoe]

This is all very interesting, Is there a way to determine by serial number or something, whether or not my 808-8A's have tangerine phase plugs or not. There must of been a point in time when you could expect to see them that would relate the a serial number?

I have had a single 808-8A mounted to a 511B in my basement for some time. I just purchased another (driver only) and hope to work them into my next project. They are going to be used with DIY Smith horns.

They might be going to Bill H for a attitude adjustment but Im not sure yet. Billfort, I guess I should send them now if I plan on using them this summer sometime. Our last go around took about that much time did it not?

RC

 

[Billfort]

Yeah, no border crossing involved but I think sending them now for summer use would be about right.

 

[bowtie427ss]

Is there a way to determine by serial number or something, whether or not my 808-8A's have tangerine phase plugs or not

AFIK, all 808-8A's are old style annular slit phase plugs, the "A" and "B" suffixes are what denote which type of driver they are.