Help me match these parts please....

[bfish]

I understand. While it doesn't have a label, it does have a part number which can be cross referenced and verified... every bit as good as a label.

At least it would be if it hadn't been altered. That's why I said earlier that it "started life as" a 423-8Z.

If you take the time to use the cross reference I linked, by checking cone numbers etc, you should be able to see if any of them match. If the 4" paper dust domes are the only alteration, that's not a huge problem for your application, in fact it might be a good thing.

Added;
You can get the self-adhesive 1/4' felt at WalMart. Look in the section with furniture sliders. One pack of 2, brown ~4x6" sheets.

Added later
On the 2 with the vented dust caps, make sure you can't see "clear thru" the vent front to back. They may have left the original aluminum domes in place, I've seen that done to cover dented alum domes.

<font color="#FFFFFF" size="1">[ September 21, 2008 12:56 PM: Message edited by: bfish ]</font>

[GM]

Originally posted by bfish:
..........but being open clear thru is a big no-no for a tuned box, especially one loaded down further with a horn.

<font size="2" face="Verdana, Helvetica, sans-serif">I can't help but wonder the condition of the VC since it's been run with virtually no box loading protection behind it.......

GM

[GM]

WRT the XOs, they may have replaced bad caps with whatever they had on hand/whatever that when suitably wired up matched the OEM's cap value 'close enough'. If you can't measure capacitance you'll have to submit a wiring diagram of each along with the values stamped on them.

GM

[GM]

Speakers mounted up near/at the ceiling should be inverted to load the vent, so if anything, the horn driver would be closer, not farther from the top plate. FWIW, for studio, etc., monitoring, the horn was normally in the port: http://www.lansingheritage.org/image...ome/page02.jpg

GM

[ClassicComics]

I am running over to a speaker repair shop near me, they have been there about 20 years and also rent out PA gear etc... I am going to see what they would charge to recone my 421-8a with the tape repair and see if they can test the voice coil on the one vented on both ends... also going to get a speaker repaired from my klipsh subwoofer and just ask if they do Altec HF diaphram replacements etc... as long as I am there...

[GM]

Well, seeming conflicting info is what you get when you give folks only a piece of the 'puzzle'.

Yes, if inverted up high you tilt the whole speaker so that when you look up you're staring down the HF horn's throat.

Anyway, since this is a behind screen app, the speakers should be right side up with the HF horn on top and positioned such that the HF horn's midpoint is at 2/3 screen height to lock the dialog in place, then angle it down so that its line of sight is ~2/3 the way between the front and back row and split the difference between the ear height vertically. Note that as a general rule you want to angle the left/right channels so that they point at the 2/3 back focal point, though in a small room its acoustics come into play, so you may have to fiddle a bit to get the proper angles and distance from the screen.

WRT mounting an angled horn, I've used alum. or steel brackets, though if you prefer to use the A7's wooden strip in the front, just loosely secure it to the horn, set the angle and snug them up. They don't need to be a flush mount, just tight enough for the wood to damp them.

GM

[ClassicComics]

How will I know if there is anything wrong with the voice coil (besides having a dead woofer) and assuming the woofer isn't dead how can I fix the damage? I already applied the foil tape to the back of the hole.

Crossovers - I will see what I can get together.

As far as the position of the speakers, they will be behind my acoustically transparent screen and I built stands for them so that they would be behind the actual screen. The top of the screen is 2 3/4" from the ceiling and then the screen frame, behind the screen material, is 3" wide.

When I 1st built the stands I was going to use the horns mounted in the boxes since that's how my main two already were. So I built the stands so that the tops of the speakers would be about 5 inches below the botom of the 3" frame of the top of the screen. See picture below:



Then after everyone was telling me how much better these speakers sounded with the horns closer to the woofers, with the horns mounted on top of the boxes above the woofers and since I got 3 more boxes that were being used with the horns on top, I figured I'd go that way. So, I flipped my stands on their sides, so now the top of the horn will be about a 1/2" or so, I'll have to double check, below the 3" top frame of the screen. See pic below:



I'm a little confused by what you are saying. Should I cut the foam to make the horn level with the top of the speaker and then tilt the speaker slightly? How much tilt? I don't want that much as my back row (where I sit) is about a foot off the floor on a riser. Ceiling height is about 8'. Also, the speakers are right now only about 4 1/2" back from the screen material. Also, any concern about shooting sounds at an angle through accoustically transparent material instead of straight through? Any and all thoughts, explanations and knowledge would be appreciated!!

THANKS!!

Also, for reference, here is a picture with the screen up:



Added later:

866239: If you want to send me a PM and tell me how much you want for the speaker I can think about it.

<font color="#FFFFFF" size="1">[ September 22, 2008 03:52 PM: Message edited by: ClassicComics ]</font>

[Cal Weldon]

For the wood strip out front, I ripped down a 2X4 to suit and dadoed a slot for the horn flange to slide into. Then if you use bolts, you can pinch the slot as you tighten, This will help the damping. I did the same for the board between the 511 and 811 horns with a slot on either side. See avatar.

<font color="#FFFFFF"><font size="1">[ September 23, 2008 11:28 AM: Message edited by: Cal Weldon ]</font></font>

<font color="#FFFFFF" size="1">[ September 23, 2008 11:29 AM: Message edited by: Cal Weldon ]</font>

[ClassicComics]

Cal - do you have a picture of this mounting?

I am a very visual person.

THANKS!

[ClassicComics]

GM - sorry about that I really do appreciate all the help. I keep treating whatever thread I am on as if it is connected to all my other posts in one big long thread (which it is in my mind - but not in real life). Plus, I have changed my mind a few times as well, based mostly on all the stuff I am learning on this forum.

Just to make sure I understand correctly, right side up on my speakers is woofer at the top of the box, not the bottom, correct? And then mount horn on top of the box. And then as far as angling the horn, I should measure 2/3 of the way up the screen and try and get the height of the center of the horn equal to that spot (hmm, if my math is correct - screen height is 60" and 2/3 of is about 40", so that would put the center of the horn at about 51" using my current stands... yikes, I'm about 11" off. I guess I'll have to re-evaluate my stands.... someone had talked about flying the speakers from the ceiling in another thread, that's why I put them so high... although with the horns cabinet mounted I would probably be about right on.... hmmm. Either way, I should then angle the horn down so it hits in between the back row and the one in front of it in between both ear heights. I think I am getting this.... please correct me if I am wrong anywhere.

I am unclear as to what you mean on the left and right speakers, do you mean angle them in towards center or angle them down towards the floor?

What about what 866239 said about the voice coils of the horns needing to be mounted 19.3" from the front edge for proper phasing? Does that mean the driver needs to be 19.3" from the front of the cabinet?

When you say the A7's wooden strip in the front, do you mean the top front lip of the box? Or something else? What about my idea of using a 3/4" piece of wood mounted to the top of the cabinet? not worth the effort?

I keep forgetting you're in Chamblee... are you familiar with North West speaker repair in Smyrna off of Windy Hill rd? That's where I went earlier today.... the are repairing a Klipsch subwoofer speaker for me (refoam), and I showed the guy there my two 421-8a woofers, he said the one with the tape repair needs to be reconed ($85 - a 10% off coupon) - I am going to do it, but since I only need 3 of my 4 woofers I am going to wait a bit before doing it. He said my other 421-8a (the one that was vented on both ends) was in good shape and he said my foil tape job would do the trick. He also took a look at my dividing networks and said the capacitors all added up the same on all of the ones I have, just that the two matching ones had newer matching capacitors, and the others ones had older ones that were added up to equal the right number. I also talked to him about new diaphrams in the 808-8a's and he was going to order the parts from GPA anyway, and when I told him the price they quoted me, he said that was a good deal, especially with the remagnetization which he couldn't do there anyway. Guy was full of knowledge... we talked for quite awhile....