6 ohm speakers - uprate to 8 ohm?

[David WE Roberts]

Yes - and over time with continuous usage the resistance decreases further and further.

[thirty-six]

I used to use the old thin stuff meant for 405 line TV but have ran out.

[thirty-six]

A reel of simple pendant wire IS generally more correct than much so- called speaker wire but when co-ax isn't conspicuous and there is a cheap source it is always my preferred speaker wiring in permanent installations.

[thirty-six]

From which storybook did you find that gem?

In the gauges required, particularly in distant installations, basic co-axial is usually cheaper. There are advantages in the transmission of audio frequencies probably related to phase shift which occurs with 'speaker wire'.

It's still best to throw out the bell-wire even with a close-coupled installation.

[thirty-six]

The reactance of twin wire will knock off both high and low frequencies, due to the way negative feedback loops work, leaving the sound more like telephone reproduction.

[thirty-six]

[e-mail]...

They usually do well in filling a large room but don't always stand up to extended listening.

[Ian Jackson]

Care to explain (briefly)?

[Andy Wade]

Highly unlikely - the capacitance won't be that much higher than with any other type of 2-wire line. Most amplifiers are stable with load capacitances at least a couple of orders of magnitude more than presented by a typical speaker cable run .

Possibly OTT. The only thing that matters is the total (loop) resistance in the speaker lead, but it doesn't have to be absurdly low, only low compared to the resistance of the speaker's voice coil - since that is what dominates in the 'damping circuit'. In practice there will be no audible or measurable improvement from reducing the cable's resistance below about 5% of the nominal impedance (and 10% is quite good enough if you're not super-critical). Hence the heftiness of cable required is entirely dependent on the length of run.

We'd all agree on that, I hope:

[Dave Plowman (News)]

Just as well - it would be a poor match for the speaker in a 625 line TV.

[Bill Wright]

The inner core would be 0.6mm so the return resistance would be quite high per unit length.

Bill

[Bill Wright]

Hey! We've invented the telephone!

Bill

[Bill Wright]

Please keep formulae to a minimum.

Bill

[Andy Wade]

That will be difficult...

Don't worry Bill, the proposition is piffle.

[The Natural Philosopher]

Oh its no story. Not a few rather poorly QC'ed or poorly designed amps will go mad with a capacitor on the output, and coax is a few tens of pF a foot

NORMALLY You put an RF choke in series with the speaker in the amp design itself. Some cheapskates leave it out...

[The Natural Philosopher]

I love the way you tell em.

Not much experience of electronics then?

[Huge]

Interesting to see that thirty-six's skills extend beyond talking utter bollocks about cars to talking utter bollocks about other topics.

[thirty-six]

e:

There is reactance and the amplifier responds to that compounding the lack of linearity in what isn't a transmission line.

[thirty-six]

It's acceptable. The greater linearity (lack of reactance) makes it a much better choice.

[thirty-six]

There's normally a loudspeaker unit at the end of the wire. Your claims are fallacious.

[The Natural Philosopher]

doesn't matter if there is.

The endpoint impedance of the wire at HF/RF is of little impact on its impedance overall - that's ALL about capacitance and coax is simply more capacitative than T & E. something like 50-150 pF/meter.

Twin lead - 300 ohm ribbon cable - is in the 10-20pF/meter range.

I would expect that T & E would fall somewhere between the two.

I see you know the square root of f*ck all about the design - inadvertent or otherwise - of RF oscillators. Or power amplifiers.

I must have designed 10-20 in my time and probably the thing that took longest was making sure they were RF stable with anything stuck on the output.

By number, about 6-10 components are there to actually ensure this, and to ensure its safe whatever the bozo user does to the output short of stuffing live mains into it,

Capacitors across teh output are just another ting you check for..

Bear in mind that some cheapskate manufacturers will substitute cheaper or lower spec devices and/or simply 'remove components' until the design doesn't work. Then put the last one back in..

I saw a lot of that in early far east kit..parts simply missing off the PCB.

Some was legitimate - they would use old boards with newer transistors that didn't need the extra stabilising. Some was not tho. Pure penny pinching.