Help with 4320

[dkorn]

After a long wait, I got a pair of 2405 and a pair of 3106 in order to retrofit my 4320 with UHF.
2 Questions:

-I took the lenses off the baffle to unscrew the horn (more on this later). They were glued. What do you people recommend to reattach them? Velcro?

-Previous owner (John Entwistle) had a on/off switch fitted for the horn. prolly to use 4320 as some LF unit. Anyway, upon inspection, I find out horn was wired "backwards", i.e.: red terminal on the Xover was actually connected to black on the horn. The switch terminals was where inversion took place.

Is this normal wiring? Was this horn wired wrongly?

I haven't checked the other speaker yet.

thanks for any help

[boputnam]

Hey...

The lenses on many/most latter versions was held-on with Velcro. Works fine...

There is no harm in Entwistle having cross-wired the HF - that would have given a "boost" in the range of the crossover. Maybe he prefered that sound - but it is not "as designed" by JBL, which calls for Red (or GRN or solid non-black)-to-Red.

[Hofmannhp]

Hi Bo,


as everybody knows, John Entwistle plays bass guitar.....:rockon1:
.he don't need a horn.....:yes:

HP
(former, and sometimes today "Who" fan)

[ngccglp]

Hi korn,

I replaced the original black velcro on my 4333A with the clear plastic ones from 3M. There are heavy duty ones and can hold the lens very firmly in a vertical position.

David

[dkorn]

So --the big question: what would be the correct wiring of a rigged 4320 consisting of a:
2215B LF
2420/2307 compression driver/horn
2405 UHF driver
with original 3110 and newly added 3106 Xovers?
Currently, the 2420/2307 are (were) connected in reverse to the 3110.
Thanks!

David Korn -who doesn't like Korn.

[dkorn]

Here's what I did, and it sounds good to me:

3110 terminal 1 (LF) ->2215B red
3110 terminal 2 (LF) ->2215B black
(that's the way it was)

3110 terminal 3 (HF)->3106 black
3110 terminal 4 (HF) ->3106 red
(I think that's inverted from "normal" connecting rule)

3106 terminal 1 (LF) ->horn black
3106 terminal 2 (LF) ->horn red
(so that's another inversion, meaning in phase with LF)

3106 terminal 3 (HF)->2405 red
3106 terminal 4 (HF) ->2405 black
(that's inverted)

I should maybe have hooked up the 3106 to the 3110 the other way around for the sake of simplicity, but at this point, my head started to ache. It sounds good like that, I'll try other ways on a fresh head !

[boputnam]

Sorry, David - been tied-up in rehearsals, and whatnot...

I can't tell about the 3106. What do you mean "inverted from 'normal' connection"...?

And, if done this way, it seems the 2420 and 2405 are all in-phase with the 2215B. :confused: I wonder if it would be more "pleasing" were they not. But, to test that, I would NOT connect the 3106 differently, I would crosswire the individual drivers...

But in the end, it's what sounds good that matters...

[Alex Lancaster]

Hi:

AFAIK, in the 31xx xovers, terminals 1 and 4 are "red", 2 and 3 "black", the xovers do the inversion electrically, I think the manual is in this forum, if not, I surely have it.

[boputnam]

Hey, Alex...

That is exactly how I read the schematics.

[dkorn]

If 1 and 4 are red, looks like my 2420 and 2405 aren't properly wired, but the 3106 is.
Would be curious to check the manual if you have it...

[dkorn]

I got to fix a loose terminal in my 3110 and it's sealed. How would you go around opening it? Drilling the rivets that are on the side?

[boputnam]

Originally posted by dkorn
...looks like my 2420 and 2405 aren't properly wired, but the 3106 is. Bingo! That's what I'm thinking. But would be interested in your hearing of the difference... :hmm:

[Alex Lancaster]

Let me look for the "manual", it is like an owners´, not service, I´ll post it ASAP.

[dkorn]

quote:
Originally posted by dkorn
...looks like my 2420 and 2405 aren't properly wired, but the 3106 is.
Bingo! That's what I'm thinking. But would be interested in your hearing of the difference..

Me too !
I'll try that tomorrow with a fresh set of ears.
My first tests were on one speaker only, as I had not retrofitted the other...

[Alex Lancaster]

DKorn:

If You want to take it completely apart, drill out the rivets, put the bottom in a hot plate, (it is filled with wax), and when You can, pull out the cover; For reassembly, reheat the wax, dunk all the components and either re-rivet or use sheet metal screws.

Hope it helps.

[dkorn]

hum... does "dunk" mean "reassemble like it was before"?

How much wax is there in there?

[boputnam]

Here's Links for the:

3106 Schematic (http://www.jblproservice.com/pdf/Network%20Schematics/3106%20Network.pdf)

and the

3110 Schematic (http://www.jblproservice.com/pdf/Network%20Schematics/3110%20Network.pdf)

[Alex Lancaster]

The caps, x-formers, etc, are loose, and held in place by the wax, they are not on a board; enough wax in there.

[Paul Joppa]

The crossover is second order, so if the woofer and tweeter had similar time delays you would expect them to be connected in reversed phase. Connected in the same phase would be appropriate in the tweeter was delayed by a half wavelength.

The problem is, they made a longer horn after the first few years. I think it was 12 to 13 inches long, vs. the 8 or 9 inch original. That longer horn, crossed at 800Hz, had the same wavelength delay as the 8 inch horn at 1200Hz, which was a recommended crossover frequency. The difference is about a quarter wavelength, or 90 degrees phase. So probably you can connect the tweeter either way without causing a cancellation notch at crossover.

Now all you need to do is find out which phase convention was used on the drivers, since JBL switched standards at one time, and "away from the magnet" is not always "away from the listener".

[dkorn]

Darn! I'll stick to what my ears tell me.
I connected everything colour-to-colour and in the absence of colour coding, according to the xover schematics 1/4=red, 2/3=black.
Sounds good. Little wobbly in the low mids on some recordings (feels not "tight" enough), but that's more to do with the room. Or, maybe the LF drivers need reconing...
Thanks for all the advice. Quite happy with the extra sizzle.

[boputnam]

Originally posted by Alex Lancaster
Let me look for the "manual", it is like an owners´, not service, I´ll post it ASAP.

Alex has emailed me the 31xx series owners manual, which I have compiled into a .pdf (too large to post). If you're interested in a copy, please pm me your email address!

Thanks, Alex! :thmbsup:

[dkorn]

Well, after replacing the main terminals on the 3110 by banana-plug compatible gold-plated ones, and re-checking for proper wiring (and finding an inversion by all means), here I am with the finest pair of 3-ways 4320s, with strong bass, nice ooomph in the mids (ah, drums!) and sizzling highs, that sound good at any level (well, any level compatible with the police not breaking in). :rockon1:
All that for less than the price of ugly modern speakers with hyped, fake lows ! :die:
My advice to anyone not happy with the sound of their speakers: check the wiring! Thanks to Bo and Alex for the Xover owner's manual. :thmbsup: