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Old 17th May 2021, 11:17 pm   #1
Linnovice
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Default Power amp to speaker?

What is best? Longer speaker cables from power amps with shorter interconnects or longer interconnects and shorter speaker cables, or, does it matter?

I’ve just completed the revamp of my listening room. Consequently, I’m about to start returning my system into the room. I have in my head where I’d like to put the power amps and speakers but not sure how cable runs are likely to effect output. I’d prefer short interconnect and longer speaker cabling but don’t want to shoot myself in the foot! Advice would be gratefully received.
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Old 17th May 2021, 11:36 pm   #2
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Default Re: Power amp to speaker?

Loudspeaker impedances go all over the shop as frequency is varied, so there will be some interaction with the inductance and resistance offered by the speaker cables. Whether this is audible is a matter of scale and opinion.

However, the output impedance of a preamp and the input impedance of a power amplifier are a lot more consistent over frequency.

So, if you are going to have long cables somewhere and short cables somewhere else, it is advantageous to have the speaker cables shorter, and have the power amps near the speakers.

However, you do need to consider the screening of the long, low-level cables, and you have to consider the effects of earth loops. Well-designed power amplifiers have the ability to sense the earth appropriate to the pre-amp. ALL signals are differential, but it's easy to not see this where they are strongly unbalanced.

Just coin a catchy term for it and it'll start a cult... how about "no-wiring"?

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Old 18th May 2021, 9:10 am   #3
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Default Re: Power amp to speaker?

General rule is simplicity, practicality and convenience.
Far easier to make or buy longer speaker leads than interconnects.
Power amps have low output impedance so driving 20 foot+ cables is no problem. If their resistance bothers you buy thicker cables. It is easier to have everything switched from a single location.

If your pre-amp has relatively low output impedance (200 ohms or so) it will have no problem using long interconnects. But that usually needs mains power from two or more different outlets. That can lead to ground loops and odd interference pick up. (If you are using a valve pre amp with high output impedance, don't think about using long interconnects.)

Does it matter, in small rooms not a lot really with modern equipment.
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Old 18th May 2021, 10:44 am   #4
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Default Re: Power amp to speaker?

Also as you age, you can no longer hear the top end anyway so
not so critical.
I use just 2 core mains lead for my speakers.
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Old 18th May 2021, 10:45 am   #5
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Default Re: Power amp to speaker?

The crucial point made above that deserves stating explicitly, is that it is not so much the length of a cable itself that has an impact on the sound, but how the cable interacts with the devices at either end. Therefore, it is not possible to generalise about which is preferable to lengthen and which to shorten, for minimum impact.

The parameters of interest are usually cable capacitance vs. line output impedance for signal cables, and cable resistance vs. speaker impedance for speaker cables. There is also the earth-loop issue to consider when spanning significant distances with unbalanced interconnects. As also stated above, correctly-designed HiFi equipment should be tolerant of any reasonable cable lengths involved in a domestic setup, so that it can be sited for convenience and appearance. Subject, of course, to the caveat that not all HiFi equipment is correctly designed.

The most important exception would be for preamps with high impedance outputs, typically valve units without matching transformers, that cannot drive significant cable capacitance and need to be sited adjacent to the power amps. In contrast, with professional audio equipment using well-designed electronically balanced intputs and outputs at +4dBV, I expect to be able to run many hundreds of metres of 110 ohm twisted pair cable before having to pay any attention to cable parameters.
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Old 18th May 2021, 11:27 am   #6
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Default Re: Power amp to speaker?

If your preamp has low source impedance differential output then keep the speaker cables short. If the preamp output is single ended and low impedance then its not so clear. Either way, experiment with long preamp / poweramp cables to see if there is a propensity to picking up interference in your environment.

Otherwise, lengthen the speaker cables but make them a bit thicker to compensate. Nothing fancy is need, just a lot of copper and as flexible as you need it to be!

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Old 18th May 2021, 11:51 am   #7
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Default Re: Power amp to speaker?

Quote:
Originally Posted by Linnovice View Post
I’d prefer short interconnect and longer speaker cabling .
I think you'll be absolutely fine doing that. I seem to remember that Douglas Self recommends the use of 2.5mm twin and earth mains cabling for loudspeakers - dirt cheap, available everywhere, and as good as any other type of cable for feeding loudspeakers. Just leave the earth core unconnected. It's difficult and unwieldy cable to run above the floor, so my preference is to run that cable under the floorboards from your amplifier position to speaker locations, terminating the t+e on the skirting boards with suitable sockets. Then do the last few yards from sockets to amps and speakers in something more flexible.

Just my preference!

Mike

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Old 18th May 2021, 1:50 pm   #8
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Default Re: Power amp to speaker?

Long .speaker leads, almost anything will work well if the resistance is less than about 10% or less then the "rated impedance" of the 'speaker. Maplin used to do some rather nice very flexible 1.5mm2 cable for this, the flexible factor was my priority in getting a reel.
 
Old 18th May 2021, 2:14 pm   #9
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Default Re: Power amp to speaker?

Orange lawn mower cable, as per Quad demos.
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Old 18th May 2021, 3:26 pm   #10
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Quote:
Orange lawn mower cable, as per Quad demos.
Also gettable in a fetching white oval form, fits in a bit better to the modern household scheme. 12 quid for 50m from Toolstation.
 
Old 18th May 2021, 6:15 pm   #11
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Default Re: Power amp to speaker?

How long is 'long'?

You talk about a 'listening room' which implies that no cabling is likely to extend into the tens-of-metres range - so IMHO it can really be disregarded as an issue: at audio frequencies you're talking a really-irrelevant fraction-of-a-wavelength so 'designing' as transmission-lines is silly: 600-Ohm balanced would be utter overkill.

[If you're delivering enough audio to cover an event-space that's half a mile across - as I did on occasions - then you should be looking at 100V-line distribution]
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Old 18th May 2021, 6:28 pm   #12
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Default Re: Power amp to speaker?

Thank you all for your contributions. Going by the suggestions I have very little to worry about either way.
My room is 3m x 3.5m, the speakers (Aktiv Linn Kabers) will go along the shorter wall, my preamp (a Linn AV5103 + 3 AV5105 power amps) will go along the longer wall just over halfway down. I anticipated making up my speaker cables with Van Damme 6 core 4mm sq cable but the suggestion of 2.5 T&E sounds interesting, I may well give that a try first
Thanks again for making the effort, it is very much appreciated.
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Old 18th May 2021, 6:35 pm   #13
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Default Re: Power amp to speaker?

Rather than 2.5mm T&E - remember if you want lower resistance you can also get T&E in 4mm 6mm and 10mm too [the last couple are generally used to wire-up things like range-cookers and electric showers - some of which are rated at 15Kw so will be pulling 60 Amps from the mains].

If your speaker-cabling needs to handle 60 Amps you're getting _really_ serious!
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Old 18th May 2021, 7:00 pm   #14
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Default Re: Power amp to speaker?

I guess that the correct speaker leads are those of similar resistance to those used by the speaker designers when they did their various subjective and objective tests.

I have the (possibly incorrect) impression that the Linn designers may have used something idiosyncratic.

Martin
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Old 18th May 2021, 7:24 pm   #15
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Default Re: Power amp to speaker?

In perspective, 1mm cable has a resistance of less the 0.02 ohms per metre, twice that for there and back. That is three parts of f**k all over a few metres. And with 'speakers resistance is all that matters, forgetting that having different colours for each core makes getting the polarity the same for each (I assume stereo) 'speaker. For your average living room bell wire is more than adequate.
 
Old 18th May 2021, 8:01 pm   #16
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Default Re: Power amp to speaker?

Haha!! Love it!
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Old 18th May 2021, 8:06 pm   #17
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Default Re: Power amp to speaker?

Linn’s propriety K600 cable (as recommended) looks to be approx 4mm sq. No longer available but occasionally sold on eBay for around £30 per metre. I have some but getting it tidily around a system can be liken to wrestling a boa constrictor ��
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Old 18th May 2021, 10:29 pm   #18
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Default Re: Power amp to speaker?

Van Damme do twin HiFi cable in a variety of sizes - www.vdctrading.com/shop/van-damme-cable/speaker/HiFi-Speaker-Cable-Oxygen-Free-Copper/

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