I bought some nice Belden cable from BlueJeans a while ago and I've decided it's time to bi-wire my speakers and see if it makes a difference. Before anyone starts sniggering, let me state for the record, I'm not a DIY person as such, nor do I pay any attention to sales-pitching idiot salesmen, I just want to try it for myself. So I got the fattest wire I could - 10awg/3mm. My problem is a simple one - how do I shove two of these into each terminal on the back of my amp. The amp is an ME240 Integrated, and here's the solution I've come up with so far: I'm using bananas at the moment with a single 14awg wire in each, so I thought I'd get a few packets of male and female spade lugs from Jaycar/similar and connect the two wires inside the head of the banana, then bend them slightly and clamp the screw down hard and insert into the amp. I want to avoid forked spades direct to the terminals as I'm concerned about them falling out (having just browsed an article on this at soundstage). As I see it this is an almost idiot-proof solution. I'd obviously need to shave the female spade of it's plastic coating and possibly file it down to fit - not entirely sure about this yet, as I haven't done all the measurements. There's always using two males in place, curled a bit to lock into the head, I might try both. I've also thought of using eye-socket connectors, but I'm not sure of the quality/metal composition and if it will make a difference. Red & Black Gold Spade QC Lugs Pack - Jaycar Electronics Female Spade - Blue - Pk.8 - Jaycar Electronics Male Spade - Blue - Pk.8 - Jaycar Electronics Mini Female Spade - Blue - Pk.8 - Jaycar Electronics Piggy Back Female Spade - Red - Pkt. 8 - Self Sealing Quick Connectors - Jaycar Electronics Chasis Mount Quick Connect Spade Terminals - Jaycar Electronics Red & Black Large Eye Terminals 8GA Pack - Jaycar Electronics Blue 8mm Eye Terminal - Pack 8 - Jaycar Electronics Sorry about all the links, these are just my ideas, and I have no special affection for Jaycar, if someone can direct me somewhere else, I'd appreciate that as well. I just want to get this right first time. I can't afford to short a terminal and lose any of my components.
That SOUNDS like it should work fine. You could also just connect the two 10 AWG to a short length of something smaller (that fits into your bananas). Or maybe those bent "pin" connectors would fit into one banana, except I don't know if there are any pin connectors that accept 10 AWG.
It won't matter much if you have a short length of something else that they both run through, just near the banana plug. The main idea is that they run separately for MOST of the cable length. The reason for doing that is probably so that all of the voltages induced in the cable won't have to "intermingle", i.e. arithmetically sum with each other. But the voltages induced across a short segment will be proportionately small.
All conductors have distributed resistance and inductance. A current in a conductor will induce a voltage between the ends of the conductor (and, actually, between every set of two points in the conductor), due to Ohms Law, V = I x R, AND due to the inductance's differential equation, V = L x dI/dt, where dI/dt is the time-rate-of-change of the current. (Note that even a small-amplitude current could induce a large-amplitude voltage if the current were fast-changing.)
By bi-wiring, e.g. running the bass and treble in separate pairs of wires with two pairs per channel, the treble speaker input doesn't have to see the cable and ground-return voltages induced by the bass signals, and vice versa.
One way to do it might be to use banana "Y" connectors. You could plug one Y connector into each of the four amp outputs. Then you'd just need four banana connectors with one conductor each, to connect to each channel of the amp, so standard two-conductor cables with two banana connectors on each end (or at least on the amp end) could then be used, two per channel. (Of course, that would violate the principle of using the fewest connectors. But maybe you'll move on to bi-amping soon, anyway, and it will be easier to re-use the more-standard cables, then.)
It won't matter much if you have a short length of something else that they both run through, just near the banana plug. The main idea is that they run separately for MOST of the cable length. The reason for doing that is probably so that all of the voltages induced in the cable won't have to "intermingle", i.e. arithmetically sum with each other. But the voltages induced across a short segment will be proportionately small.
All conductors have distributed resistance and inductance. A current in a conductor will induce a voltage between the ends of the conductor (and, actually, between every set of two points in the conductor), due to Ohms Law, V = I x R, AND due to the inductance's differential equation, V = L x dI/dt, where dI/dt is the time-rate-of-change of the current. (Note that even a small-amplitude current could induce a large-amplitude voltage if the current were fast-changing.)
By bi-wiring, e.g. running the bass and treble in separate pairs of wires with two pairs per channel, the treble speaker input doesn't have to see the cable and ground-return voltages induced by the bass signals, and vice versa.
One way to do it might be to use banana "Y" connectors. You could plug one Y connector into each of the four amp outputs. Then you'd just need four banana connectors with one conductor each, to connect to each channel of the amp, so standard two-conductor cables with two banana connectors on each end (or at least on the amp end) could then be used, two per channel. (Of course, that would violate the principle of using the fewest connectors. But maybe you'll move on to bi-amping soon, anyway, and it will be easier to re-use the more-standard cables, then.)
Thanks, that's a neat, elegant solution. Just a couple of small follow-ups: What can I use to step down the wire-gauge, what type of connector should I be searching for? I'm a little concerned about the threads on the bananas unwinding themselves - is it wise to use, say, a thread-locking glue on the screw-head of the banana? And lastly, for while I've been thinking about inserting something like a thin sheet of foam between the bananas/binding posts to isolate them from one-another if they should come off. Is polystyrene foam safe in this instance - around electronics? My amp runs fairly cool due to internal fans, but the bananas are raw metal - perhaps a bit of heat-shrink done with a hair-dryer would work better?
If you live in Melbourne, you are quite welcome to see first hand what bi-amping can do for a speaker.
Frank
Frank
Thanks for the offer Francec, I'm living in Tasmania at the moment, but when I migrate back to the mainland, I might take you up on that. I've been toying with the idea of building my own passive Linkwitz Pluto's and bi or tri amping them with a pair of mini amps from here: TrendsAudio - High end but not high priced audio products ! Using the pre from my ME, and running the ME across the treble and each of the T series across the mids. Just a thought. Linkwitz PLUTO ŠT—v�@Ž©�ìƒXƒs�[ƒJ�[�mDIY Audio SSD�n
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