On Sat, 27 Nov 2004 19:02:14 +0000, Chris Morriss wrote:

snip
I was looking at using Speakon connectors on a home-made 200W (mean) per
channel amp, but thought I'd buy a pair first to see how they were
constructed. They really have a very small contact patch. If you want a
low-resistance connection then I suggest you stay with a high-quality 4mm
banana. Speakons are mechanically robust when they are connected, so are
ideal for PA use.

Electrical view:

I don't know about the speakon connections, but I can assure you that it
isn't the contact area that is important here (look at the diameter of
30A fuse wire - and that is a continuous rating and doesn't "blow" on
surges until you get to over 100A!). It is the contact pressure. You can
get a very low resistance connection providing that the contacts are clean
and that the pressure is high enough.

Wrap-around screw terminals are just about the worst. The contact area is
fairly high but you can't usually exert enough pressure to really cut
through the oxide layers to get a really good connection. From an
electrical view you really need at least 50v on these to puncture the
oxide layers and make them effective.

Strangely enough, the old DIN flat+round pin connector was pretty good
electrically (but the mechanical side left a lot to be desired). Small
double contact area but very high point contact pressure with
self-cleaning "scraping" action on a good socket. Unfortunately they
wouldn't take decent cable.

Standard bannana plugs use a lower contact pressure but the area is a bit
higher. Unevenness in the surfaces means that it is often not brilliant,
but generally ok up to about 10A providing that the voltage is high enough
to break down oxide films (not good for speakers in theory, but they are
usually ok if you keep them clean by unplugging & replugging now and again).

Bunch pin plugs are multiple line contact with a higher pressure on each
line to dislodge the oxide and should, in theory, be better.

In general, gold plated connections are an improvement over tinned ones
*providing that both surfaces are plated*. Don't mix tinned & gold plated
connections as this can lead to a corrosive layer forming. Generally
tinned-tinned connections are better than gold-gold for frequently
broken connections as some of the gold plating is lost each time the
connection is remade. That can eventually expose the base metal layer
(especially on the cheaper gold plated units) and lead to similar
corrosion problems.

In view of the above, IMHO the ultimate speaker connection is probably
tin-plated, small surface area (preferably 2 or more points of contact),
high contact pressure & scratching self-cleaning action on each
connect/disconnect action. If speakons match that then go for 'em! ;-)

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk