NFB and load characteristics

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Can I ask you, do you have any suggestions regarding the max distance for speaker cables. I use only shielded QED Silver Spiral cable.

Speaker Wire

I wouldn't ever use a lamp cord for other reasons like aesthetics but I generally just buy the appropriate gauge generally I run larger than needed by one size and use a wire with a nice insulator and good ends.

If your ends or wires are silver I guess they conduct electricity better than copper but at what cost...


:cop: Thread split from Here.

PM
 
Speaker Wire

I wouldn't ever use a lamp cord for other reasons like aesthetics but I generally just buy the appropriate gauge generally I run larger than needed by one size and use a wire with a nice insulator and good ends.

If your ends or wires are silver I guess they conduct electricity better than copper but at what cost...

Niko, I appreciate your input. If you are promoting your own cables then please let me ask you the same question...what distance - maximum - for speaker cables from amp?

Reeler
 
It depends on the gauge, in that article they state over 50FT seems to have an effect on 10khz-20khz range, all my runs are under 25FT.

For cables, I pretty much just buy a half decent roll of cable 12awg-16awg generally, throw on some banana clips and call it a day. Inspect them every few months or so to make sure connections are still solid and they are not getting much moisture or oxidation damage etc. Generally that means I end up replacing them every few years as well, between moving, pets etc they get chewed up, the ends get beat up even if I don't notice a difference in sound I like to keep it clean.

You should actually take a bit to read through it if you want some details.
 
Niko, I spent many years choosing my cables, (at one time I was taken in by manufacturer's claims), ....In the end I chose to buy cables by the roll and make my own.

I am happy with my choice but I am ignorant of the science behind my choice.

I am pleased that the 'QED Silver Spiral' obliterates surrounding interferance but it's all down to the "distance" this can hold out on!

So...is 5 metres too much, perhaps 7 metres, or 3 metres...before I get interference?

Edit. PS: I solder my own so I can do the cables either by 'line' or 'XLR'.

Please, I don't want to appear cheeky, I really want to understand minimum/maximum speaker distances.
 
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For me, using predominantly monoblocks located at the speakers, I regularly advise and use speaker cables that are less then 1m long and often less than 600mm long.
The interconnects from the group of source equipment to the volume control can be upto 4m long.
The interconnects from the volume control to the Power Amps can be even longer.
If I get around to using the CAT5 strung around the house then these last interconnects will be approaching 50m to the most remote rooms from the comms cupboard. I really need a radio controlled remote operation pre-amp/selection box for that comms cupboard, until then I am "in room" only.
 
Andrew, I find your advice in line with my own thoughts. Short speaker cables to amp and long interconnect (XLR) to amps. Thank you for your contribution.

It might be difficult with my project but is is achievable.

This leads me to amore difficult topic..............[perhaps for another title. PLUGS!!]
The advantage of having seperate plugs for separate amps?

PS....My maximum run of leads is 7m.
 
For me, using predominantly monoblocks located at the speakers, I regularly advise and use speaker cables that are less then 1m long and often less than 600mm long.
The interconnects from the group of source equipment to the volume control can be upto 4m long.
The interconnects from the volume control to the Power Amps can be even longer.
If I get around to using the CAT5 strung around the house then these last interconnects will be approaching 50m to the most remote rooms from the comms cupboard. I really need a radio controlled remote operation pre-amp/selection box for that comms cupboard, until then I am "in room" only.

Andrew, Why the concern about longer speaker wires. 1 meter or less is a pretty conservative recommendation. I am assuing the usual caveats about adequate wire gauge etc. Could you briefly discuss this?
 
Andrew, Why the concern about longer speaker wires. 1 meter or less is a pretty conservative recommendation. I am assuing the usual caveats about adequate wire gauge etc. Could you briefly discuss this?

If I am following what Andrew is trying to relay is simply that he uses very short speaker wires, being monoblock amps can be places nearly next to the speaker they are powering. I mean realistically the shorter your speaker wire the better, not many can argue that, what you will notice maybe another thing.

I also maybe slightly misguided here but I have been under the assumption that speaker wires are inherently practically immune to noise due to the power levels of the signal flowing through them. Someone with some more knowledge chime in?
 
Why the concern about longer speaker wires.
1.) every flow and return pair (cable) has L + C + R, the longer the cable the more of each.
2.) Every amplifier (or any source driving a flow and return pair) sees the L+C+R as part of the load that the amplifier has to drive. The more reactive components, in general, create more difficulties in setting up the amplifier to deliver a clean signal to the receiver.
3.) every speaker is driven by the source via the L+C+R of the cable. The speaker expects to see Rs=0r0 and the sound coming from the speaker can be "tuned" to suit a precise Rs (or complex impedance) as chosen by the speaker designer. When the Rs is different from what the speaker designer chose for his "tuned sound" then the speaker finds it impossible to reproduce the clean signal from the amplifier. The speaker reacts to the cable impedance.
4.) the shorter the speaker cable the less the cost.
5.) the shorter the speaker cable the smaller in cross sectional area it can be. A small increase in resistance is not an increase in reactive loading. 6m of 6sqmm of speaker cable has the same resistance as 600mm of 0.6sqmm of speaker cable. If the resistance of the 6m cable had a deleterious effect on the speaker sound then the 600mm cable can use a slightly higher cross sectional area to reduce the resistance of the short cable if needed. Not nearly so easy to increase the cross sectional area of the 6sqmm cable.

Long or short interconnects have a much smaller effect on the source and receiver that they connect. The Line Level source and the Line Level Receiver are much more tolerant of the L+C+R of the interconnect. In the extreme, terminated coax can transmit a near perfect 100MHz signal over a distance that simply decreases the signal available at the receiver. For audio and a decade or so either side, the simple 2core flow and return is sufficient if the Source and Receiver are designed to be tolerant of a bit of reactive cabling.

As a final note, this explanation does not support nor argue against speaker cables and interconnects having a "sound".
My own opinion is that cables do not have a sound. The L+C+R and thus the complex impedance of the cable affects what is connected to the ends of the cable. It is the amplifier that changes it's signal in response to the complex load impedance. It is the speaker that changes it's sound in response to the non zero Rs that is connected across the speaker terminals. High Damping Factor in an amplifier can never return Rs to zero, after passing through a reactive cable.
 
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NFB and the effect of load characteristics

AndrewT,

you may as well now mention what the negative feed-back path sees as opposed to the test conditions having an 8 ohm pure resistor hanging at the output of an amp.

The NFB actually worsens this whole situation since the output is becoming an input source with no correlation to the input.

I personally do not think that people hear differences in speaker cable, but they hear their amplifier's characteristics changing due to what is hanging on the output due to overall NFB.

Interestingly enough, why are there a couple of guys swearing by zero NFB amps, could this be one important reason. I would like Nelson to comment on this one since he essentially designs zero overall NFB amps.

Maybe we should start a new thread, these last posts developed in total contrast to that started and it is becoming a rather interesting discussion.

Can the moderators perhaps move the last few comments to a new thread - maybe something called NFB and load characteristics as I am sure more members would subscribe to this rather than heat sinks.

Kind regards

Nico
 
Hi Guys,

I thought this to be a very interesting topic and asked the Mouse to split the thread because I am quite confident that this single topic is what make two amplifiers sound different. Not just the speaker cable, but how the load reacts as an input source and how it affects the actual performance of an amp with over-all NFB.
 
you may as well now mention what the negative feed-back path sees as opposed to the test conditions having an 8 ohm pure resistor hanging at the output of an amp.

The NFB actually worsens this whole situation since the output is becoming an input source with no correlation to the input.
W. Jung wrote a paper on why an opamp must be considered to have 5input pins. Not just +IN & -IN.

This extra input is also why some decry the benefits of the DC servo. It injects non-music signal back into the amplifier.

It is also why I have adopted the Pi version of the Thiele Network on the output cable.
 
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Hi Guys,

I thought this to be a very interesting topic and asked the Mouse to split the thread because I am quite confident that this single topic is what make two amplifiers sound different. Not just the speaker cable, but how the load reacts as an input source and how it affects the actual performance of an amp with over-all NFB.

Not all of NFB react that bad. I do found it happened at most amplifier that using differential input stage with common emitter, they creating noises.
Place your amp on bench, then play it with no input and sine current source at the output with dummy load, then see the output waveform, you will see that noises. It doesn't happen on current feedback amplifier.
There also some way to minimize it by positive feedback, high DF output (huge feedback), and others.

Hi, Andrew.
Short cable is the best one, but there another configuration that need long cables, like ceilings, directed directed sound waves, and some other, that needs cables and single amplifiers that has high DF, yes high DF, like line array and other directed waves. I don't like high DF sounds for single loudspeaker, but they will better at some of that configuration and sounds better too. Easier to manage etc., more amplifiers are more difficult.
 
Andrew T,

I agree with your maths. You are worthy of your education.

However, you will have to agree that it is difficult for people to equate the finite equations to the "black box" for sale in the shop window.

Customers don't know about "resistance" within componants and Manufacturers don't tell them.

Regarding another matter, my design to place 5 amps onto one wooden board.
is aimed at feeding Left & Right speakers & Centre, only. Bass & Trebel separate.
 
Nico Ras

I would be interested to know, with this split thread, what you think of Luxman's design....."Duo Beta".....which was all about their Luxkit design? This amp, which I hope to put 5 of, on one wooden table to service my musical requirements, The Japanese solved the problem of NFB in the 1980s by incorporating "Duo Beta", but nobody listened because the UK and America were trying to salvage their own Hi-Fi industry.

Now, perhaps, you will see why I am so perservering in my quest! The NFB issue was solved many years ago but gone un-noticed.

sigh
Reeler
 
For me, using predominantly monoblocks located at the speakers, I regularly advise and use speaker cables that are less then 1m long and often less than 600mm long.
The interconnects from the group of source equipment to the volume control can be upto 4m long.
The interconnects from the volume control to the Power Amps can be even longer.
If I get around to using the CAT5 strung around the house then these last interconnects will be approaching 50m to the most remote rooms from the comms cupboard. I really need a radio controlled remote operation pre-amp/selection box for that comms cupboard, until then I am "in room" only.
__________________
regards Andrew T.

What Andrew suggests is the best way to go, monoblocks as close as possible to the speaker system.

Cheers
Arturo
 
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