PDA

View Full Version : 4320 update w/2405



dkorn
08-28-2003, 03:18 AM
Hello,
Alongside my much beloved 4310, I just bought a pair of 4320 (belonged to the late John Entwistle !) and I'm thinking of adding a 2405 slot tweeter to enhance high frequency response. I'm looking for information and advice on the overall procedure --installation, connection, which crossover model, stuff not to overlook or forget, etc. Thanks in advance.
David

Tom Loizeaux
08-28-2003, 04:31 AM
Sounds like a good idea. I did the same thing to my pair of old 4320s.

You'll need a pair of 2405s (or 077s) of course, and a pair of 3106 crossovers.
My 4320s came with two cut-outs in the rear panel. If yours did also, then installing the 3106s is easy. I assume you have 3110 crossovers in these already. ? If so, you take the wires from he 3110's high freq. outs and run them to the 3106's inputs. Then take the 3106's low outs and run them to the compression driver and run the 3106's high outs to the 2405. Wiring them to be in correct phase is a little tricky. More on that later.
Most 4320s came with a cut-out that holds the 2405. It is located low and off-center, but if that's OK with you (it was with JBL) then the only mod you'll need to make is to drill new holes to line up with the four in the 2405's frame.
If you get these ready to install and you have further questions, please ask.
I think you'll be very pleased with these 4320s after the slots are in them.
Check my photo and you'll see one of my 4320s with the 2405 installed centered above the compression driver lens.

Tom

dkorn
08-28-2003, 08:28 AM
Thanks Tom.
I will sound like the ultimate badger, but how to you access the innards of the 4320 to install the 2405? --my guess is one has to take the LF speaker away, but I'd rather not make a blunder with a LF speaker that probably weighs a ton. There's a cutaway for a 2nd crossover indeed, it's currently closed by a woodpanel.
A couple more questions:
1. Is there only one flavour of 2405, impendance wise?
2. What's the tricky part regarding the wiring of the 2405?
Thanks !
David

Tom Loizeaux
08-30-2003, 06:58 AM
Yes, accessing the inside of the 4320 requires removing the woofer. If you're new at this, be carefull that you don't damage the cone or surround. I sit in front on the cabinet while on the floor and remove all but the bottom screw, since my 4320s don't use JBL clamps, and then slowly remove the bottom screw while pressing my foot on the front rim at the bottom. Once the last screw clears, the speaker can be pulled from the cabinet. Unclip the wires to it and put it aside in a safe place.
Shine a light inside and a lot will be revealed. As you remove drivers or crossovers draw a diagram of which color wires go to exactly which contacts.
The cover panel can be removed as well as the cover on the tweeter hole.
As far as I know, there is only one impedance version of the 2405. Though it meters near 8 ohms, it is really closer to 16 ohms in it's operating range.
When you get your 2405s and 3106 crossovers - we can talk you through wiring these up to maintain correct polarity and phase.
Keep us posted.

Tom

dkorn
08-30-2003, 07:31 AM
Thanks Tom, that's exactly the kind of "real life" advice I needed. I ran a search on 2405 and found this long thread on polarity. Interesting (scary?) ! Now to find a couple of 2405 and the crossover.

Doctor_Electron
09-07-2003, 12:45 AM
Or...if you can obtain the 0.16 mH inductors, you could copy the third-order high-pass portion of the #3107 network (used in the 4350). Its input connections ("common" and "high Freq") could be connected in parallel to the existing network's input connectors. Use 100V minimum voltage rated, non-polarized film caps. Remember...the built-in resistance of the inductor affects the network section's "Q", and therefore the steepness of the filter's slopes. For example, the 1.8 mH inductors associated with the 2440 drivers have a DC resistance of about 3.5 ohms each, far more than you would expect. This value is critical to the filter's function!
3107:
http://www.jblproservice.com/pdf/Network%20Schematics/3107%20Network.pdf

boputnam
09-07-2003, 11:39 AM
Originally posted by dkorn
...how to you access the innards of the 4320 to install the 2405? --my guess is one has to take the LF speaker away...?

A couple more questions:
1. Is there only one flavour of 2405, impendance wise?
2. What's the tricky part regarding the wiring of the 2405?

Hey...

Tom has given some outstanding guidance there - lucky he's been through this exact upgrade!

I've two points:

1) When removing the LF (i.e., woofer) I always lay the cabinet on it's back. Period. Even the monstrous 4345's. Period. Too easy to lose grip of the LF, and risk not worth it. You risk damage to the baffle, and who knows how the LF would come to rest! Also, you may need to carefully ease a putty knife beneath the LF frame in a couple places around the frame to loose it from the baffle. Once free, lay a towel on the baffle face where you can rest the motor while you disconnect the leads. Set LF aside, face down (hold by frame back - watch for leads) and then restand cabinet for work if you need to access the rear.

2) The 2405 comes in both 8-ohm and 16-ohm iterations. The "vintage" 2405's are 16-ohm. The newer and still sold are 8-ohm, look a bit different in the motor area, but take the same baffle-cut as the "vintage". I prepared and posted a composite image of the two 2405 iterations elsewhere on this Forum, on Page 3 here: 4345 Monitor Plans - Link (http://www.audioheritage.org/vbulletin/showthread.php?s=&threadid=314&perpage=15&highlight=vintage%202405&pagenumber=3) I've not had the chance to compare A/B 8-ohm vs 16-ohm in same-same, and should know better than to speculate, wildly... :duck: Check this out: 3105 Network - Link (http://www.audioheritage.org/vbulletin/showthread.php?s=&threadid=459&highlight=3106) from the inimitable Giskard, as usual. Looks to me like you're going to want to stick with the 16-ohm, vintage iteration, but there I go again... :duck:

You might use the Search function for the 3107 network - Mr. Widget had some very intersting comments in the 2404 vs. 2405 Thread - Link (http://www.audioheritage.org/vbulletin/showthread.php?s=&threadid=560&highlight=3107)

Oh, yea, on wiring: Just hook 'em up the way their supposed to be, Red lead to Red UHF terminal. The 3106 has the 2405 running JBL Standard (negative): 3106 Network - Link (http://www.jblproservice.com/pdf/Network%20Schematics/3106%20Network.pdf)

So, how'd you come on Entwistle's 4320's, anyway?

Make sure you post some pics and keep us current on progress! ;)

4313B
09-07-2003, 12:33 PM
Maybe this will help -

boputnam
09-07-2003, 12:42 PM
Originally posted by Giskard
Maybe this will help - Or confuse... :confused:

So, they don't even sell an 8R diaphram for the 2405H (the nominal 8-ohm copy)... :no: ??

dkorn
09-07-2003, 02:12 PM
So, how'd you come on Entwistle's 4320's, anyway?

When he passed away, a pro audio broker in the UK bought tons and tons of stuff, that was sitting in no less than 3 warehouses --as you can guess, besides being JBL endorsees, the Who were also linked to a lot of manufacturers.
So, said broker had to buy everything, and then had to move the stuff fast ! Those 4320 were part of those "priced to go" pieces. I just happened to check the broker's webpage at the right time, and I thought I'd give them a try --I already own a pair of 4310s that I love. Having said that, he had put an ad previously on rec.audio.pro, so it wasn't really a secret.
Also, about the 4320s, I noticed the four small vents in the back of the enclosure were filled. And, Entwistle had a switch fitted on both speakers to shut off the HF.

So, in short, should I keep my monies for the real vintage 2405, or will the 8-Ohms do? Ebay has mosty newer ones. I can wait, though.

boputnam
09-07-2003, 03:30 PM
Originally posted by dkorn
I just happened to check the broker's webpage at the right time, and I thought I'd give them a try. Having said that, he had put an ad previously on rec.audio.pro, so it wasn't really a secret.

Also, about the 4320s, I noticed the four small vents in the back of the enclosure were filled. And, Entwistle had a switch fitted on both speakers to shut off the HF.

So, in short, should I keep my monies for the real vintage 2405, or will the 8-Ohms do? Ebay has mosty newer ones. I can wait, though.

Hey...

Interesting stuff - thanks. Futzing around in the shop today I had some more thoughts, but first:

Can you tell us more about the broker, and that "rec.audio.pro" - we might have further uses for them! ;)

On those ports being "filled - I don't know the 4320 and whether this is de rigeur or not. The HF off-switch, however has me suspecting Entwistle had these rigged to either emphasize his bass lines on recording playback, or maybe he actually played through them in his listening room (without having to drag out the road gear). Interesting... :hmm:

On the vintage vs newer 2405, I had thought that 3105 Thread suggested the 16-ohm version gave a smoother xover; then Giskard posted the diaphragm replacement parts list, suggesting JBL only sell the 16-ohm version. I'm waiting for some more clarity on that - you could pm him...

But, back to the other thought: Not to take anything away from Tom's great suggestions, but I wondered the pros and cons of just going for a 4332-33 set-up (Lansing Heritage 4332-4333 - Link (http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1974-4332-4333.htm) ). That would enable you to biamp, and if not that, would keep the passive crossover to one (3133) instead of two in series. As I say, I don't know if there's any benefits to this, except the 4332-33 are outstanding.

Here's a Link for the 3133 Network - Link (http://www.jblproservice.com/pdf/Network%20Schematics/3133%20Network.pdf) (passive, three-way) and the 3133A Network - Link (http://www.jblproservice.com/pdf/Network%20Schematics/3133A%20Network.pdf) for the biamp option (then you'd need an external active xover like the 552 M series brochure - Link (http://www.jblpro.com/pub/electronics/mseries.pdf))

dkorn
09-07-2003, 03:46 PM
With all the help I'm getting here, I feel I must give back ! That broker is called Funky Junk, they have offices in Paris, London, Milan and Stockholm. Website at www.proaudioeurope.com (http://www.proaudioeurope.com) .
I'm a little confused with all these options now... I sort-of would prefer to keep the 4320s closest to their original state rather than turning them into a project. Adding a 2405 seems OK to me in that respect--after all the cutout is there, so it's not really a "mod". I may sound silly, I know.

boputnam
09-07-2003, 04:09 PM
Originally posted by dkorn
I sort-of would prefer to keep the 4320s closest to their original state rather than turning them into a project. Adding a 2405 seems OK to me in that respect--after all the cutout is there, so it's not really a "mod". I may sound silly, I know. Not at all.

Most here prefer Vintage gear to stay "as built". But, since you recognize the benefit of improving the UHF response by adding a 2405 (exactly as JBL did... ;) ), you already are altering the original. You are de facto creating a 4332-33, only with a different LF (the 2215B vs 2231). I was just expanding the question here to address what the "preferred" option might be in considering the crossover, too.

Macht Nichts.

Dave G
09-07-2003, 04:43 PM
Hello dkthorn

Thats makes 2 known pairs of speakers of this vintage and type in the UK.

I can help with info and beware of who you deal with for parts and advice as I was ripped off by 'experts' in this country.

I have a C50SM which is the same box with 375 mid and 075 bullet. The vents should be in the front in the form of ports no rear venting on these?

Dave G
09-07-2003, 04:58 PM
Need to get these set properly!

boputnam
09-07-2003, 05:09 PM
Originally posted by Dave G
I have a D50SM which is the same box with 375 mid and 075 bullet. The vents should be in the front in the form of ports no rear venting on these? Hey, Dave G...

That is a beauty! Do you know what the network is? And, is it passive, or are you biamping?

Nice! :D

4313B
09-07-2003, 05:53 PM
Originally posted by boputnam
Or confuse... :confused:

So, they don't even sell an 8R diaphram for the 2405H (the nominal 8-ohm copy)... :no: ??
Never have to my knowledge. I've owned 077's, 2405's, and 2405H's and there isn't any electrical difference. JBL Engineering treats the 077/2405/2405H as a 10 ohm load.

From my post in the last forum:

"Ok, so we have been around the block on this one with the LE15A and LE85.

Is there such a thing as an 8 ohm 2405H? JBL only sells a D16R2405 diaphragm.

With the 2421 where there was an 8 and 16 ohm version sold, they have both diaphragms available."

JBL basically treats the 077/2405 as a 10 ohm transducer. That's all it's ever been regardless of what they stamp on the outside to appease hi-fi consumers or Pros.

The LE85/2420/2421B is usually treated as a 12 ohm transducer.

The LE15A is usually treated as a 10 ohm transducer.

boputnam
09-07-2003, 06:54 PM
Originally posted by Giskard
JBL Engineering treats the 077/2405/2405H as a 10 ohm load. Got it. Thanks.

Oh, and I tried to preserve that groovy royalblue - ya dig? :rotfl:

dkorn
09-08-2003, 02:21 AM
Originally posted by Dave G
Hello dkorn

Thats makes 2 known pairs of speakers of this vintage and type in the UK.

I can help with info and beware of who you deal with for parts and advice as I was ripped off by 'experts' in this country.

I have a D50SM which is the same box with 375 mid and 075 bullet. The vents should be in the front in the form of ports no rear venting on these?

I'm in Paris, France, actually !
The enclosures are branded "4502WX". There are four pegs sticking out a 1/2 inch in the rear panel. Broker had a pair way back and told me they were vents that had been filled. Looks more to me like distance holders, installed to insure a certain distance between the rear panel and a mounting wall, whatever. Anyone care to confirm? I could chisel them out if that's the case
I'll take a pic when I have a minute. They are in pretty good condition, but they probably weren't in a smoke free environment !

Dave G
09-08-2003, 04:57 AM
Mine had large hanging hooks in rear. As they would have been hung in front of the desk from the wall. Of course I filled the holes with dowels.

My cabs have 4502 with no letter prefix on the metal badge.

These came and were designed passive. The combination of these drivers and crossovers was known as a 'S8' option. The other blank in the rear is filled with a N7000 type crossover. These are rare to say the least in europe. You might find some friendly forum members willing to sell you some as they are considered slightly below par compared to latter designs. Oh the other is a 500 hz crossover compared to yours which is likely to crossover at about 1200 hz as the bigger format drivers work down lower.

Is everything else on these working and sounding good?
:rockon1:

dkorn
09-08-2003, 05:51 AM
Hanging hooks... That sounds logical. Mine have prolly been soffited at some point, or hung, and then those pegs were put in the holes.
The WX refers to them being walnut instead of "white". The crossover is probably the 3110 (it's not mentioned outside), that crossovers at 800Hz according to the 4320 brochure.
Apart from that, yes, they sound absolutely great. I feared that they wouldn't without some room tuning, EQ, change of amplifier, etc. Also, I had bought a pair of Quad 405 before getting them, in case more power would be needed to move those 2215 (and possibly bi-amp them if needed).
Well, I just hooked them to my Denon PMA 2000 (big, heavy 2 x 80W preamp/amp) and it just... works. Actually, I can't set the volume over a quarter of its range. I live in central Paris, and I can actually walk to the end of the street and still hear the music. Better than a Walkman!
They sound really good, even at low level --lots of space. At higher levels, Mids are a little hard/harsh (part of the JBL sound, I guess, it's also the case on the 4310), which is why I want to fit 2405s, thinking it may somewhat help by offloading the HF driver. Of course, the crossover frequency wil be @ 8K, way above "mids", but I hope to be able to achieve a smoother overall balance in the sound without resorting to EQ. If not, well it can't hurt to have an extended frequency range, or?

Dave G
09-08-2003, 07:02 AM
A lot of forum members do experiment with different amps and preamps. You might be able to reduce apparent midrange harshness by using a valve nice valve amp. I amp using a old accuphase transistor amp and a old pioneer valve thing. The quads are quite good, my friend has one. He also has 4312 so I know exactly why you are keen on this equipment!

The bottom line is that these are still good even today, many will not understand of course. I don't even consider them that big!

Look foward to the pictures!

Tom Loizeaux
09-20-2003, 08:51 PM
After doing some more reading and research recently, I think my "4320s" may actually be 4331s! Check my photo to the left and see the cabinet in the lower right. They came with 2215 B woofers, 2420 compression drivers w/ 2307 horns and 2308 lenses and had no crossovers. I added the 2405s in new holes centered above the lenses and installed two pair of banana plugs and a 3106 in each cabinet. So now they are bi-amped with the 2405s running passively from the 3106 crossovers.
I have discovered that JBL made a few variations of the 4320 that hade a same cabinet, but used different port numbers and lengths depending on the woofers used. Some were passivly crossed over, some were bi-amped, some were 2-way, while some were 3-way. In any case, they were the beginning of JBL's studio monitor line.

Tom

Alex Lancaster
09-20-2003, 09:33 PM
4333B's had a different cabinet, one port, 2 holes for the 2405, so You could get less or more separation, 2312 horns (800Hz), and 2231 woofers, just like the L300's, also they had a 3 way xcover not 2 2-ways.

Alex.

dkorn
09-21-2003, 02:19 AM
Speaking of which, if anybody has a pair of 3106 to spare, give me a whistle. I just found a pair or 2405 for my little UHF project...

sgaggy
12-21-2006, 05:31 PM
After doing some more reading and research recently, I think my "4320s" may actually be 4331s! Check my photo to the left and see the cabinet in the lower right. They came with 2215 B woofers, 2420 compression drivers w/ 2307 horns and 2308 lenses and had no crossovers. I added the 2405s in new holes centered above the lenses and installed two pair of banana plugs and a 3106 in each cabinet. So now they are bi-amped with the 2405s running passively from the 3106 crossovers.
I have discovered that JBL made a few variations of the 4320 that hade a same cabinet, but used different port numbers and lengths depending on the woofers used. Some were passivly crossed over, some were bi-amped, some were 2-way, while some were 3-way. In any case, they were the beginning of JBL's studio monitor line.

Tomsorry mister tom but i know ,how i biamp in passive mode 3110e n7000 cross,thank and i wait your gentle aswer,i,dont speak well english.grazie vito.