Upgrading to Banana Plug / pin Binding Posts on 4311b's and 4313b's

[CliffK1968]

Dear JBL Forum,
Seeking some input on binding posts upgrades to a couple of JBL speakers. I had firs researched the JBL Forum and found one post, with no replies, I hope to be more successful.

I have a few pairs of JBL 4311b’s. 4312a’s and a pair of 4313b’s. I am looking to upgrade the binding posts to a modern ‘banana’ plug connector on a pair of the 4311b’s and the 4313b’s. I also have a pair of 4312a’s – which have the banana style binding posts.

Is this fix or upgrade even possible by a knowledgeable JBL repair person on the 4311’s and 4313’s? What is generally involved if it can be done, and what should I be mindful of, things to ensure are done and things to avoid?
Thanks in advance for the input.
8505185052

[rdgrimes]

Pretty simple once you remove the crossover board from the cabinet. I've done a few. What you're looking for is one the many available "5-way" binding posts that accept any kind of connection. You'll find many at Parts-Express.com. I've used these:
https://www.parts-express.com/dayton-audio-bpa-38sn-hd-binding-post-banana-jack-pair-satin-nickel--091-1247
They offer an assortment of connect options inside.

The only caveat with the JBL is the depth of the board inside the back baffle. Its about 7/8" deep - so any binding post that sticks out past that will get dinged if the speaker winds up on its back and could break the crossover board or just push the post through it.

[SEAWOLF97]

I've swapped to 5 ways on all of mine , they do take
bananas, but actual bare wire through the post hole is
much better ... contact wise . IMHO

[CliffK1968]

RDgrimes,

Thanks for the input,, that is a question I was hoping to ask, so the board is 7/8" inch thick? So I would need a binding post that has a stem that depth to pass through the board? Do you know if on the 4311b's and 4313b's do the posts protrude on the interior above the crossover, below the crossover or are part of the crossover? Do I need a stem with a minimum of 3/4 stem depth for interior of cabinet?

SeaWolf, thanks for the input, but most of the speaker cables I have or am looking at, they don't even come with a bare wire option... Cardas cables or Synergistic all come terminated in banana or spade...

Many thanks,
Cliff

[Mr. Widget]

...but actual bare wire through the post hole is
much better ... contact wise . IMHOCould be, I haven't bothered to measure the DCR difference.

I usually use bananas for the convenience. Can't say any of my systems have suffered because of it. ;)


Widget

[CliffK1968]

Pretty simple once you remove the crossover board from the cabinet. I've done a few. What you're looking for is one the many available "5-way" binding posts that accept any kind of connection. You'll find many at Parts-Express.com. I've used these:
https://www.parts-express.com/dayton-audio-bpa-38sn-hd-binding-post-banana-jack-pair-satin-nickel--091-1247
They offer an assortment of connect options inside.

The only caveat with the JBL is the depth of the board inside the back baffle. Its about 7/8" deep - so any binding post that sticks out past that will get dinged if the speaker winds up on its back and could break the crossover board or just push the post through it.

RDGrimes,
I better understand what you are saying now.. but do you know the thickness of the wood or back "plate" by which the post has to extend through to the inside? In looking at various binding posts, some seem much longer than others...
Thanks,
Cliff

[rdgrimes]

RDGrimes,
I better understand what you are saying now.. but do you know the thickness of the wood or back "plate" by which the post has to extend through to the inside? In looking at various binding posts, some seem much longer than others...
Thanks,
Cliff

The rear baffle is 7/8" or there abouts. The crossover board is just old fashioned Masonite on the older models, maybe 3/16" thick. How far the posts penetrate that isn't usually an issue. The posts that I linked fit pretty well after very slight reaming out of the holes. The shafts are knurled so you want them to fit tight enough for those "teeth" to grab the material. Then you just tighten the nuts and connect the wires by whatever means you like. Washers may help, (and also cover your mistakes). But the tighter those knurled shafts fit in the holes, the less likely they are to spin.

[SEAWOLF97]

.
https://www.stereophile.com/content/cables-case-solder

assuming that a banana plug has similar limitations to a 1/4 TRS plug



The RCA phono plug has some important drawbacks as a connector, but it has two profound virtues: its wiping action (assuming that the plug is correctly sized to make a tight fit) and its relatively large metal-to-metal contact area. Another connector used for audio, the phone plug, is terrible by comparison. (I'm referring both to the ¼" phone plug used for full-size headphones and amateur microphones, and also to the 3.5mm mini-phone plug used for walkabout products—lightweight headphones, small cassette recorders, and portable players.)

When a phone plug of either size is inserted into its socket, there is virtually no wiping action and no tight fit between mating metal surfaces. Within a phone socket, the round shaft of the plug makes contact only with V-shaped tips at the ends of spring-metal fingers. The area of contact between each finger and the plug shaft is tiny—a fraction of a thousandth of a square inch.

[Mr. Widget]

.
https://www.stereophile.com/content/cables-case-solder

assuming that a banana plug has similar limitations to a 1/4 TRS plug.Nope, bananas are more like the RCA plug, they scrape the surface as they are inserted and they have four spring loaded contacts that make a very snug connection.

FWIW: Banana plugs are used throughout labs for non RF connects. For RF and highly sensitive test gear they use BNC connectors.


Widget

[SEAWOLF97]

Nope, bananas are more like the RCA plug, they scrape the surface as they are inserted and they have four spring loaded contacts that make a very snug connection.

FWIW: Banana plugs are used throughout labs for non RF connects. For RF and highly sensitive test gear they use BNC connectors.


Widget

all the bananas that I've used have a bulge in the center of the shaft where contact is made, at best they can only scrape half of the shaft that they are inserted into.
Depending on the length/depth of that shaft, the bulge may not actually be very far in (on a shallow shaft) ... and the loaded contacts (bulge) seems to weaken after repeated insertions. YES, not theory ..I've experienced it.

sure, I also have them on systems where speakers get swapped out often and also have them on the 250Ti's where the wire guide holes in the binding posts won't accept any wire bigger than 16ga. Opened up the 250's to replace the binding posts, but they are soldered into the crossovers and decided that replacement wasn't worth the effort.

they are not my first "go to" option.

[BMWCCA]

all the bananas that I've used have a bulge in the center of the shaft where contact is made, at best they can only scrape half of the shaft that they are inserted into.
Depending on the length/depth of that shaft, the bulge may not actually be very far in (on a shallow shaft) ... and the loaded contacts (bulge) seems to weaken after repeated insertions. YES, not theory ..I've experienced it.
It might help to upgrade your bananas. I've been extremely pleased with the Neutrik connectors and especially these I used on my 6-Moons White Lighting cables:

http://audioheritage.org/vbulletin/attachment.php?attachmentid=42820&d=1258163589