Banana plug

[Swerd]

Now i need to find out what size i need for my AVR

Patrick

I really geeked out over banana plugs in my previous post. I'm sorry if I made it sound like the differences in shaft size make a big difference. They don't. They do matter, but in a small way.

Here's a brief history of my experience with banana plugs. I've had various different ones at different times. They were all standard or modified bananas. The standard bananas worked with my gear, but were a tiny bit too large. Over time, I noticed 1) they could very gradually work loose, and 2) the curved springs on the shaft got compressed or even broken – they had no spring left. The modified bananas never suffered from those problems. So, when I needed more plugs, I learned to look for the modified bananas.

I've never had the locking or the BFA types. Anyone: what does BFA stand for?

 

[KenM10759]

From my point of view there are two different things to choose with about banana plugs, the shaft itself, and the method of wire connection which results in different shaped handles.

First, is the shaft, the where the electrical contact is made with the jack. There are 4 styles of shafts, the first 3 are shown below (ignore the dimensions as they are lengths). On the left is a locking shaft where it expands as a small set screw is turned. To the right is the standard banana shaft. And the two on the right are a modified banana shaft. The standard banana plugs were just a bit too large to fit well in the banana jacks on my electronic gear. They gradually worked loose. The modified bananas stay put. Which ones work for you depend on the size of the banana jacks on your AVR, amp or speakers.
View attachment 30245

There is a 4th type of shaft, called BFA
View attachment 30248

Banana plugs come in three common outer diameters. Manufactures have different tolerances, but the table below shows typical dimensions for the three sizes.
View attachment 30244

Next comes the manner in which the wire gets attached to the banana plug and the size & shape of the handle. There is a wide variety of these, and it comes down to individual preference. I personally like the Sewel Dead Bolt type.
View attachment 30250

Your top photo is a total screw-up. None of those are anywhere near FOUR CENTIMETERS.

Being shaped, exactly where are they measuring across them? The tips are all around 3.9mm diameter to get into the straight 4mm bores of most multi-way binding posts. The variation of those holes is generally 4mm -0/+.15mm from those I've measured.

Furthermore, I have the ones on the left, they fit nominal 4mm sockets of the binding posts of any of my myriad KEF and Hafler speakers, and lock in quite firmly as the outer ring is tightened clockwise and those pins force a tapered one inside to spread the tip outward. Mine are all from Blue Jeans Cable, though the identical ones are apparently offered by GLS.

In my experience, the cheapest ones use a grade of (gold-electroplated) copper that has little "spring" to it so those with the 4 slots and expanded can loose tension. That's why I prefer ones that lock mechanically.

 

[Swerd]

Your top photo is a total screw-up. None of those are anywhere near FOUR CENTIMETERS.

I only chose that photo because it showed several types of banana shafts in one single photo. I believe I did say to ignore the dimensions in that photo.

I never bothered to convert those numbers in something more meaningful to me, because they obviously were too large to be shaft diameters. By the way, 4 cm long is about 1.6". That's about right for that type of plug.

 

[KenM10759]

I only chose that photo because it showed several types of banana shafts in one single photo. I believe I did say to ignore the dimensions in that photo.

I never bothered to convert those numbers in something more meaningful to me, because they obviously were too large to be shaft diameters. By the way, 4 cm long is about 1.6". That's about right for that type of plug.

Actually, 4cm/40mm (1.574") is quite a bit longer than the 0.625" (just shy of 15mm) length of the BJC locking banana plug I just measured. Can you tell you're dealing with a long-experienced machinist here?

I should point out that overall length isn't important unless you're up against a wall. The distance from tip to the first shoulder IS, because I have found that some of the longer Monoprice ones were too long (nearly 20mm) and bottomed-out in the binding post before the bulge fully engaged the 4mm hole.

 

[Swerd]

Actually, 4cm/40mm (1.574") is quite a bit longer than the 0.625" (just shy of 15mm) length of the BJC locking banana plug I just measured. Can you tell you're dealing with a long-experienced machinist here?

4 cm is the length of that entire banana plug, including the handle/body.

Is that entire BJC locking plug 15 mm long, or is that the length of the shaft?

 

[snakeeyes]

RX A2060 Yamaha

Sewell Deadbolt Bananas from Amazon will work.

I have them on my RXA770

 

[KenM10759]

4 cm is the length of that entire banana plug, including the handle/body.

Is that entire BJC locking plug 15 mm long, or is that the length of the shaft?

15mm is the length from the tip down to the first shoulder where it should stop. Some binding posts aren't drilled quite deep enough so the fact that those spread out at the very tip first is ideal for getting a good connection.

I have found one defective post on a PSB Imagine T speaker that was barely 10mm deep. I just got a 5/32" drill and made it right, brass is easy.

 

[Patrick Kennedy]

Sewell Deadbolt Bananas from Amazon will work.

I have them on my RXA770

Thanks, i might actually choose them. Are they full cooper?

 

[snakeeyes]

Thanks, i might actually choose them. Are they full cooper?

Yes as far as I know. I haven’t had any issues so far. It’s been a couple years.

If in doubt, there is always Blue Jeans Cable.

 

[Swerd]

Pure copper is too soft for banana plugs, especially those leaf springs. Brass, a mix of copper and zinc, is used instead. To prevent brass from tarnishing, it's plated with gold.