Mine are 0.205mm^2 and i know some use thiner.
dave
No offense but I consider it insane to use 0.5mm dia wire as speaker cable.
I wouldn't even use that to wind an inductor.
May be as a fuse wire...
On the other hand I bet you can hear differences between speaker cables. ;-)
On the other hand I bet you can hear differences between speaker cables. ;-)
Yes we can. A lot of experimenting got us here. As the wire got skinnier, the sound got better. Any smaller gets practically unfeasible.
Speaker, amplifier,and the wire that connects them has tove considered as a system.
dave
Planet10 is right, as it goes. The cable does matter at high frequency. 😎
His example of thin conductors on the tweeter cable introduces a significant effective inductance of 20% relative to the tweeter inductance of a typical 0.05mH. A 5 metre run has an inductance of about 0.01mH. Skin effect could increase that too. The audible effect would be a slight rolloff at HF.
Impedance Calculators - Mantaro Product Development Services
How does this tie in with amplifier feedback? Feedback transistor amplifiers are sensitive to load at the top end. They actually run very short of open loop gain at even the audio frequencies. Early designs of power amp in the sixties had almost no gain at all at 20kHz. You certainly don't get open loop gain of 1000 at 20kHz. Probably nearer 50 these days unless you use MOSFET.
One of the problems is that switching devices as in Class AB amps on and off is SLOW. It produces switching distortion which is audible. The other problem is slewing distortion, which says the rise time is not improved by feedback, so a fast transient, especially into low impedance where the current demands are significant, can drive an amplifier into distortion.
Feedback - Limitations of its usefulness
Regardless, an amplifier's stability and frequency response is often improved by adding a small 8R/0.1uF Zobel at it's output, which rolls off the HF response and improves the phase margin. Would you be surprised if a 8R/1uF tweeter Zobel has an even more dramatic effect?
In summary, a tweeter Zobel and a significant cable impedance WILL be audible partly as an amplifier effect. Now that's the science. Which usually wins. 🙂
His example of thin conductors on the tweeter cable introduces a significant effective inductance of 20% relative to the tweeter inductance of a typical 0.05mH. A 5 metre run has an inductance of about 0.01mH. Skin effect could increase that too. The audible effect would be a slight rolloff at HF.
Impedance Calculators - Mantaro Product Development Services
How does this tie in with amplifier feedback? Feedback transistor amplifiers are sensitive to load at the top end. They actually run very short of open loop gain at even the audio frequencies. Early designs of power amp in the sixties had almost no gain at all at 20kHz. You certainly don't get open loop gain of 1000 at 20kHz. Probably nearer 50 these days unless you use MOSFET.
One of the problems is that switching devices as in Class AB amps on and off is SLOW. It produces switching distortion which is audible. The other problem is slewing distortion, which says the rise time is not improved by feedback, so a fast transient, especially into low impedance where the current demands are significant, can drive an amplifier into distortion.
Feedback - Limitations of its usefulness
Regardless, an amplifier's stability and frequency response is often improved by adding a small 8R/0.1uF Zobel at it's output, which rolls off the HF response and improves the phase margin. Would you be surprised if a 8R/1uF tweeter Zobel has an even more dramatic effect?
In summary, a tweeter Zobel and a significant cable impedance WILL be audible partly as an amplifier effect. Now that's the science. Which usually wins. 🙂
Attachments
That was half a century ago. There's been a lot of improvement since then. Your amplifier-related comments are simply not true w.r.t. most modern solid-state amp designs.Early designs of power amp in the sixties...
That was half a century ago. There's been a lot of improvement since then. Your amplifier-related comments are simply not true w.r.t. most modern solid-state amp designs.
Gotta love it when people trash a carefully thought out response! 🙄
So crossover and TID distortion has gone away, eh? And phase errors on feedback have disappeared? 😛
I really wonder why I bother sometimes. 😡
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Sorry, I should have been more specific.Gotta love it when people trash a carefully thought out response! 🙄
Actually, that's trivially easy. If you head over to the solid state section of the forum, you'll find there's no shortage of designs with open loop gains of 1000 or more at 20kHz.You certainly don't get open loop gain of 1000 at 20kHz.
There may be a really badly designed amp out there somewhere that still suffers from audible crossover distortion or inadequate slew rate but if so, it's very much the exception these days.It produces switching distortion which is audible. The other problem is slewing distortion...
I have no idea what you mean by "phase errors on feedback".And phase errors on feedback have disappeared? 😛
That's more like the careful reasoning I like to see, godfrey! 🙂
It's probably the output devices and their biasing that matters most in an amplifier, because you can use Class A preamps which are appreciably better than the sort of power efficient Class AB opamps used in a lot of designs. In an ideal world, we'd use Class A outputs, I suppose.
Fast semiconductor output devices have come a long way. There is still an issue with reactive loads however. The back emf will have a significant phase shift which spoils the feedback calculation that the amplifier performs to determine the output current on a low impedance output. High output impedance valve and FET amps have some strengths, because you might consider a normal speaker to be essentially a current driven device.
I find that the output bias setting on modern AB amplifiers is still a very critical one. And designing for an undemanding and flat impedance on a speaker is still a good thing to do. It even brings on the subject of series and impedance compensated crossovers, which can be more amplifier invariant.
It's probably the output devices and their biasing that matters most in an amplifier, because you can use Class A preamps which are appreciably better than the sort of power efficient Class AB opamps used in a lot of designs. In an ideal world, we'd use Class A outputs, I suppose.
Fast semiconductor output devices have come a long way. There is still an issue with reactive loads however. The back emf will have a significant phase shift which spoils the feedback calculation that the amplifier performs to determine the output current on a low impedance output. High output impedance valve and FET amps have some strengths, because you might consider a normal speaker to be essentially a current driven device.
I find that the output bias setting on modern AB amplifiers is still a very critical one. And designing for an undemanding and flat impedance on a speaker is still a good thing to do. It even brings on the subject of series and impedance compensated crossovers, which can be more amplifier invariant.
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I really wonder why I bother sometimes. 😡
Why did you bother misrepresenting that article?
Why did you bother misrepresenting that article?
What did I misrepresent? I was actually just politely quoting the source of my feedback/gain diagram, since I didn't want to draw it from scratch.
But feedback is not a cure-all. The fact is that amplifiers do sound different, and designing them is a matter of trade-offs and cost. This is why people spend £25,000 on good ones.
But the most important component is the speaker, IMO. Followed by the quality of the CD source to my surprise. Well, I would say that, wouldn't I? This is the speaker forum, after all. 😀
Hi Kimbo,
I note from your OP that you are concerned about what effects may occur if the tweeter in your active system does not employ a Zobel network across it. I too am an avid supporter of actively powered loudspeakers and have never considered Zobel networks a necessity, for the same reasons as you cited. Of course, it may be a requirement for a passive Xover, but not in an active system.
I am still surprised to see so many people still arguing over this issue in this thread, so I decided to make some actual measurements to show just how much a Zobel network across a typical tweeter really makes to an active system, if for no other reason than to justify my own position.
I first made the assumption that you are just using a standard 1” dome tweeter. So I started by measuring the impedance of a SEAS 29TAF/W tweeter that was conveniently at hand and whose measured impedance response is shown Fig 1 attached. As you can see, the impedance is as curved as a donkey’s hind leg. So if a flat impedance curve is required, I would assume that one would ideally want it to be as flat as possible i.e. like a resistor equal in value to the Re of the tweeter.
With these parameters, I was able to setup a test system using an NAD906 amplifier (similar performance as your NAD701) driving the SEAS 29TAF/W via an 18.5 foot length of 13AWG speaker wire.
Then, I connected my sound card interface (with a balanced input) across the terminals of the tweeter and the sound cards output connected to the amps input. I then measured the voltage response with ARTA’s software, which was later imported into Crossovershop for processing. The blue curve in Fig.2 (attached) shows the results of this measurement.
Next, I swapped out the tweeter for a 4.77 ohm resistor (equivalent to Re) and re-ran the measurement again with the result shown by the red curve in Fig.2.
The difference between these two curves shows the true effects on the frequency response when a Zobel network (that has been designed to completely flatten the impedance), is removed. The difference between these curves is shown in Fig.3 and as you can see, there is a peak at the tweeters low frequency resonance (~1KHz) of +0.133dB and a drop in the response at 20KHz of -0.133dB.
I leave it up to you to decide if this is going to be audible or not, but IMHO it would not be audible to a person with normal hearing. Hope this helps.
Peter
I note from your OP that you are concerned about what effects may occur if the tweeter in your active system does not employ a Zobel network across it. I too am an avid supporter of actively powered loudspeakers and have never considered Zobel networks a necessity, for the same reasons as you cited. Of course, it may be a requirement for a passive Xover, but not in an active system.
I am still surprised to see so many people still arguing over this issue in this thread, so I decided to make some actual measurements to show just how much a Zobel network across a typical tweeter really makes to an active system, if for no other reason than to justify my own position.
I first made the assumption that you are just using a standard 1” dome tweeter. So I started by measuring the impedance of a SEAS 29TAF/W tweeter that was conveniently at hand and whose measured impedance response is shown Fig 1 attached. As you can see, the impedance is as curved as a donkey’s hind leg. So if a flat impedance curve is required, I would assume that one would ideally want it to be as flat as possible i.e. like a resistor equal in value to the Re of the tweeter.
With these parameters, I was able to setup a test system using an NAD906 amplifier (similar performance as your NAD701) driving the SEAS 29TAF/W via an 18.5 foot length of 13AWG speaker wire.
Then, I connected my sound card interface (with a balanced input) across the terminals of the tweeter and the sound cards output connected to the amps input. I then measured the voltage response with ARTA’s software, which was later imported into Crossovershop for processing. The blue curve in Fig.2 (attached) shows the results of this measurement.
Next, I swapped out the tweeter for a 4.77 ohm resistor (equivalent to Re) and re-ran the measurement again with the result shown by the red curve in Fig.2.
The difference between these two curves shows the true effects on the frequency response when a Zobel network (that has been designed to completely flatten the impedance), is removed. The difference between these curves is shown in Fig.3 and as you can see, there is a peak at the tweeters low frequency resonance (~1KHz) of +0.133dB and a drop in the response at 20KHz of -0.133dB.
I leave it up to you to decide if this is going to be audible or not, but IMHO it would not be audible to a person with normal hearing. Hope this helps.
Peter
Attachments
The difference between these curves is shown in Fig.3 and as you can see, there is a peak at the tweeters low frequency resonance (~1KHz) of +0.133dB and a drop in the response at 20KHz of -0.133dB.
I leave it up to you to decide if this is going to be audible or not, but IMHO it would not be audible to a person with normal hearing. Hope this helps.
Peter

/thread
Hi Peter. Thanks so much for your thorough analysis. Very clear. Its always nice to see real world measurements bring an 'energetic' discussion back to earth. As in my case (and I'm sure the case with anyone else using active crossovers) my crossover point is an octave or two higher than the peak, the very small effect you noted around resonance is even further reduced for any listener.
Great job.
Kimbo
Great job.
Kimbo
I really wonder why I bother sometimes. 😡
Hi,
Because however well consided a post is,
its veracity depends on how well informed
the poster is, and well considered waffle
is still just not well informed waffle.
The effect and consequence of the Zobel
on the output of an amplifier cannot be
compared to any network or driver on
the other end of a louspeaker cable.
rgds, sreten.
If we exclude the resonant peak @ 970Hz and roll in the high pass filter @ around 2kHz the total range of measured effect is ~0.2dB from 2kHz to 20kHz.my crossover point is an octave or two higher than the peak, the very small effect you noted around resonance is even further reduced
Using PLB's data, can we assume that a cable set of half the length (9' instead of 18.5') would have approximately half the effect?
Would cables of ~1m (3') have less than one quarter of the reported effect?
I wouldn't count on it. It depends on how much of the effect is due to cable impedance and how much due to the output impedance of the amplifier. If the amp has a damped inductor at the output, that could account for a significant amount of the HF droop. It would be interesting to see another set of curves with a very short cable for comparison.Using PLB's data, can we assume that a cable set of half the length (9' instead of 18.5') would have approximately half the effect?
Yes, would be informative.
I have recommended very short speaker cables many times.
1' to 2' is achievable with most speakers.
A little active I just assembled has <200mm from amps to each driver.
I have recommended very short speaker cables many times.
1' to 2' is achievable with most speakers.
A little active I just assembled has <200mm from amps to each driver.
Yes, would be informative.
I have recommended very short speaker cables many times.
1' to 2' is achievable with most speakers.
A little active I just assembled has <200mm from amps to each driver.
Jeez, you have too much time;o) I think if you are more frequency deviations if listening alone or 3-4 people in room…
Peter
I'm in the process of building a pair of three way speakers. This thread has confused me even further.
I was aiming to do away with the speakers passive crossover altogether and just rely upon the active crossover.
Are you saying that I should retain the passive crossover ? It can be divided into three so that each driver has its own unique crossover feeding it.
I would be happier keeping the crossovers in place as they protect the drivers from amp failure. Except for the woofer which has its own DC protection.
The mid drivers were over £300 each.
I was aiming to do away with the speakers passive crossover altogether and just rely upon the active crossover.
Are you saying that I should retain the passive crossover ? It can be divided into three so that each driver has its own unique crossover feeding it.
I would be happier keeping the crossovers in place as they protect the drivers from amp failure. Except for the woofer which has its own DC protection.
The mid drivers were over £300 each.
Yes we can. A lot of experimenting got us here. As the wire got skinnier, the sound got better. Any smaller gets practically unfeasible.
Speaker, amplifier,and the wire that connects them has tove considered as a system.
dave
Yeah, I'd hear differences too if I'd fuse wire as a speaker cable but I prefer equalizers as tone control over stupid-sized wires.
I can't even bring myself to call the stuff you use 'cable' as that kind of implies something substantial. In fact I'd worry that I might burn down the house using your size of wire.
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