Mine was 15" 3 ways, 8 cubic foot reflex enclosure, 95 dB/watt driven by 40 watts RMS/channel. Drivers were all Electra-Voice surplus drivers. LOUD and DYNAMIC. With all the warts they had, I still haven't heard speakers with transient response like these speakers had. The louder you played them, the better they sounded. Like the old time hot rodders say - "there's no replacement for displacement." These speakers were the big block V8 of speakers, rude and crude but oh so sweet when you step on the gas.
And thanks for the memories! I had an AR turntable. I forgot I had it, and I forgot what happened to it. I haven't even hooked up a turntable in decades but I'd hook that one up if I still had it.
" .... Military spec valves can last 100,000 hours i.e. 10 times longer than their civilian equivalents. .... "
That I did not know. Thank you! jj
That I did not know. Thank you! jj
Next stupid question. And this one is sort of vague, but I can't pin anything down more specific, and I can't find the original article.
If two speaker drivers are driven in series, something-or-other characteristics of the first one will modulate the second one. That's all I can remember. It's as if distortion in the first will be additive in driving the second, or non-linearities in the first will be magnified in the second, or something like that. I'm sorry I can't be more specific, but like I said before, I'm getting old and my memory isn't what it used to be.
I THOUGHT that the problem was in a system with 2 woofers and a high crossover point to a single treble driver. That would be a 3-driver 2-way system. Anyone care to comment? jj
If two speaker drivers are driven in series, something-or-other characteristics of the first one will modulate the second one. That's all I can remember. It's as if distortion in the first will be additive in driving the second, or non-linearities in the first will be magnified in the second, or something like that. I'm sorry I can't be more specific, but like I said before, I'm getting old and my memory isn't what it used to be.
I THOUGHT that the problem was in a system with 2 woofers and a high crossover point to a single treble driver. That would be a 3-driver 2-way system. Anyone care to comment? jj
I have read a previous thread that used driver T/S parameters and mathematics to disprove what you say. Series connection can be shown not to have any drawbacks compared to parallel connection. Unfortunately, I don't have the necessary proof to hand.
The simple fact that there exists a methodical proof that is in opposition to the principles I (hazily) remember is somehow very comforting. Too many times we hear of some new discovery or insight that undermines the methods we've come to accept, and find it disconcerting. At least, I do. Thank you. jj
I found the analysis! When you've read and understood it, please explain it to me! 🙂
Originally posted by Richard Pierce:
In article <kQiX5.1753$qs2.401109@dfiatx1-snr1.gtei.net>,
Bill Whitlock <bill.whitlock@verizon.net> wrote:
>Perhaps I confused you with my answer. To restate, I believe it is OK to
>wire two 4-ohm speakers in series to present an 8-ohm load to the
>amplifier, provided that the speakers are identical.
>
>Before reading the article by Richard Clark, I believed that doing so
>would have a detrimental effect on damping factor (which can affect the
>speaker's frequency response, especially at low frequencies). Others in
>the audio field still believe this is a controversial issue.
And it is only a belief, unfounded by any physics.
The notion is thatputting one speaker in series with another can
adversely effect that damping. This conclusion is based on a
highly flawed model of what the damping in the speaker REALLY
is and what it is due to. To dispel this falsehood, it's
necessary to do a more detailed analysis of what's really going
on using the actual parameters involved.
The damping of the speakers is due to very specific mechanisms,
primarily mechanical (due to frictional losses in the
loudspeaker suspension, and some minor absorbtion losses) and
electrical (due priomarily to the DC resistance of the voice
coil). The amount of damping is measured using the "Q" factors
due to each contributing source.
The measure of mechanical damping or Q, Qms is:
Mms
Qms = 2 pi Fs -----
Rms
where Qms is the Q factor due to mechanical losses, Fs is the
resonant frequency, Mms is the moving mass of the system, and
Rms is the mechanical (frictional) losses. Notice that there is
no implicit term relating how the Qms is affected electrically,
i.e., how it is connected to the amplifier. Now, with two
drivers, we have double the mass, Mms, because we have two cones
instead of one. But we have also have twice as much suspension
and thus twice as much suspension loss, Rms. Thus the ratio of
Mms to Rms remaines the same, and thus the mechanical Qms
remains the same.
The measure of electrical damping, or electrical Q, Qes is:
Mms
Qes = 2 pi Fs ----- Re
2 2
B l
where Qes is the Q factor due to electrical losses, B is the
flux density in the magnetic gap, l is the length of the voice
coil wire immersed in the magnetic field, and Re is the DC
resistance of the voice coil. Hooking two such system in series
does three things:
1. It doubles the moving mass Mms,
2. It doubles the DC resistance Re,
3. It doubles the length of wire in the magnetic field l.
So while the intuitive leap might be to suggest that because the
resistance Re is doubled, and therefore the Qes is similarily
doubled, doing so completely ignores the other two effects.
Let's look at the ENTIRE analysis. Let's double all the
necessary quantities and plug them back into the equation and
see what happens. For Mms, we'll substitute 2*Mms and so forth:
2 Mms
Qes = 2 pi Fs --------- 2 Re
2 2
B (2 l)
and:
And we can simplify by gathering the factors together. In the
numerator, we have 3 instances of factors of 2, for a total of
8, and there is a single factor of 4 in the denominator:
8 Mms
Qes = - pi Fs ----- Re
4 2 2
B l
Simplifying one step further, ye factoring out the common factor
of 4 now in both the numerator and denominator, we end up with:
Mms
Qes = 2 pi Fs ----- Re
2 2
B l
which shows that the electrical damping for two systems in
series is identical to the electrical damping for a single
system alone. Q.E.D.
This contradicts the seemingly intuitive notion that two drivers
in series must be severely underdamped as a result of the
additional series impedance. It's not the first time that
intuition has failed to coincide with physical reality in audio.
--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPierce@world.std.com |
Originally posted by Richard Pierce:
In article <kQiX5.1753$qs2.401109@dfiatx1-snr1.gtei.net>,
Bill Whitlock <bill.whitlock@verizon.net> wrote:
>Perhaps I confused you with my answer. To restate, I believe it is OK to
>wire two 4-ohm speakers in series to present an 8-ohm load to the
>amplifier, provided that the speakers are identical.
>
>Before reading the article by Richard Clark, I believed that doing so
>would have a detrimental effect on damping factor (which can affect the
>speaker's frequency response, especially at low frequencies). Others in
>the audio field still believe this is a controversial issue.
And it is only a belief, unfounded by any physics.
The notion is thatputting one speaker in series with another can
adversely effect that damping. This conclusion is based on a
highly flawed model of what the damping in the speaker REALLY
is and what it is due to. To dispel this falsehood, it's
necessary to do a more detailed analysis of what's really going
on using the actual parameters involved.
The damping of the speakers is due to very specific mechanisms,
primarily mechanical (due to frictional losses in the
loudspeaker suspension, and some minor absorbtion losses) and
electrical (due priomarily to the DC resistance of the voice
coil). The amount of damping is measured using the "Q" factors
due to each contributing source.
The measure of mechanical damping or Q, Qms is:
Mms
Qms = 2 pi Fs -----
Rms
where Qms is the Q factor due to mechanical losses, Fs is the
resonant frequency, Mms is the moving mass of the system, and
Rms is the mechanical (frictional) losses. Notice that there is
no implicit term relating how the Qms is affected electrically,
i.e., how it is connected to the amplifier. Now, with two
drivers, we have double the mass, Mms, because we have two cones
instead of one. But we have also have twice as much suspension
and thus twice as much suspension loss, Rms. Thus the ratio of
Mms to Rms remaines the same, and thus the mechanical Qms
remains the same.
The measure of electrical damping, or electrical Q, Qes is:
Mms
Qes = 2 pi Fs ----- Re
2 2
B l
where Qes is the Q factor due to electrical losses, B is the
flux density in the magnetic gap, l is the length of the voice
coil wire immersed in the magnetic field, and Re is the DC
resistance of the voice coil. Hooking two such system in series
does three things:
1. It doubles the moving mass Mms,
2. It doubles the DC resistance Re,
3. It doubles the length of wire in the magnetic field l.
So while the intuitive leap might be to suggest that because the
resistance Re is doubled, and therefore the Qes is similarily
doubled, doing so completely ignores the other two effects.
Let's look at the ENTIRE analysis. Let's double all the
necessary quantities and plug them back into the equation and
see what happens. For Mms, we'll substitute 2*Mms and so forth:
2 Mms
Qes = 2 pi Fs --------- 2 Re
2 2
B (2 l)
and:
And we can simplify by gathering the factors together. In the
numerator, we have 3 instances of factors of 2, for a total of
8, and there is a single factor of 4 in the denominator:
8 Mms
Qes = - pi Fs ----- Re
4 2 2
B l
Simplifying one step further, ye factoring out the common factor
of 4 now in both the numerator and denominator, we end up with:
Mms
Qes = 2 pi Fs ----- Re
2 2
B l
which shows that the electrical damping for two systems in
series is identical to the electrical damping for a single
system alone. Q.E.D.
This contradicts the seemingly intuitive notion that two drivers
in series must be severely underdamped as a result of the
additional series impedance. It's not the first time that
intuition has failed to coincide with physical reality in audio.
--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| DPierce@world.std.com |
That is excellent information. I don't really understand it, but it's excellent.
It has nothing to do with the concept I was trying to communicate. Here again, I find myself in a situation where I can't get my point across clearly.
This is going to be a poor way to explain my question, but I'll try.
For two drivers in series, the electrical signal from the amplifier comes into the first driver on terminal "+". That electrical signal is, let's say, "pure". The signal goes through the speaker magnet, and is affected by the interaction between the magnet and the voice coil. The signal then appears at the "-" terminal of the first driver. Now from what "little" I understood, the state of this signal is not the same as the "pure" signal that was sent from the amplifier. It has been - for lack of a better term - "degraded".
So now that signal enters the "+" terminal of the second driver. Not only is the signal in worse shape than the original "pure" signal, but the interaction of the second driver with the signal is the same as the nature of the interaction in the first driver. So the "degradation" is compounded. Not only is the second driver getting a dirty signal, but the imperfections it displays are double what the first driver displayed.
Now please tell me that this is a worthless notion, that what I describe (poorly) here doesn't really happen. I will be wonderfully happy, gladly going about my way with relieved mind. But is it? Is it nonsense? jj
It has nothing to do with the concept I was trying to communicate. Here again, I find myself in a situation where I can't get my point across clearly.
This is going to be a poor way to explain my question, but I'll try.
For two drivers in series, the electrical signal from the amplifier comes into the first driver on terminal "+". That electrical signal is, let's say, "pure". The signal goes through the speaker magnet, and is affected by the interaction between the magnet and the voice coil. The signal then appears at the "-" terminal of the first driver. Now from what "little" I understood, the state of this signal is not the same as the "pure" signal that was sent from the amplifier. It has been - for lack of a better term - "degraded".
So now that signal enters the "+" terminal of the second driver. Not only is the signal in worse shape than the original "pure" signal, but the interaction of the second driver with the signal is the same as the nature of the interaction in the first driver. So the "degradation" is compounded. Not only is the second driver getting a dirty signal, but the imperfections it displays are double what the first driver displayed.
Now please tell me that this is a worthless notion, that what I describe (poorly) here doesn't really happen. I will be wonderfully happy, gladly going about my way with relieved mind. But is it? Is it nonsense? jj
I don't know whether this helps but I disagree.
The signal appears across both terminals. Voltage does not exist upon one point. Then, current flows in both speakers at once.
Basic physics first! When a potential difference (voltage) is applied across the terminals of a speaker, current will flow through the speaker.
Now, to deal with your 'notion' 🙂
In a series combination, an identical driving voltage appears across each of the speaker terminals simultaneously. This causes an identical current to flow through each speaker.
In other words, each speaker is simultaneously supplied with the same 'pure' voltage signal.
Now, to deal with your 'notion' 🙂
In a series combination, an identical driving voltage appears across each of the speaker terminals simultaneously. This causes an identical current to flow through each speaker.
In other words, each speaker is simultaneously supplied with the same 'pure' voltage signal.
I apologize. Maybe I'm dense, but to me, what each of you is describing is a PARALLEL hookup, is it not? In a series hookup, you have a wire from the amp to one terminal of the first driver. Then you have a wire from the other terminal of that first driver to a terminal on the second driver. the wire from the SECOND terminal of the SECOND driver goes to ground (earth), not so? So in #1, out #1, from there in #2, out #2. In parallel hookups, a wire is effectively split to feed both "in" terminals of both drivers simultaneously, and the "out" terminals are both connected to a common wire than returns to ground.
If that's not true, then I wired hundreds of air conditioners wrong! jj
If that's not true, then I wired hundreds of air conditioners wrong! jj
I was most definitely describing a SERIES circuit!
https://www.bbc.co.uk/bitesize/guides/zk37hyc/revision/2
https://www.bbc.co.uk/bitesize/guides/zk37hyc/revision/2
Electrons are not intelligent and can't anticipate. They respond to forces. There has to be a reason for them to be pulled toward one terminal from another. (as opposed to the idea that they begin a journey at one terminal..)
This assumes the drivers are the same. Primarily and ordinarily they are. Even if they weren't it may be ok, they may be sub-optimal or it may be not ok.
I saw a case recently where two series drivers that should have been behaving the same were not, at one frequency, which was found out to be a resonant box mode. This was an older design that different people have built and no one had noticed before.
I saw a case recently where two series drivers that should have been behaving the same were not, at one frequency, which was found out to be a resonant box mode. This was an older design that different people have built and no one had noticed before.
No, jimmyjoe, you are not dense! My description could equally well have applied to a parallel circuit. Hundreds of working air conditioners can testify to that! 😎
The difference is that the voltage and the current associated with each speaker in the different combinations are each of different magnitude.
For example, take two identical 8Ω speakers and apply a signal voltage of 8V.
In series, each speaker would have 4V across it and 0.5A flowing through it.
In parallel, each speaker would have 8V across it and 1A flowing through it.
I think the mistake you are making is calling them in and out. AC in speakers doesn't see it like that.
In his defence ABD, by "So in #1, out #1, from there in #2, out #2" jimmyjoe is simply describing the sequence of series wiring i.e. into one speaker then out into the other.
He described it correctly and more fully in his opening statement.
He described it correctly and more fully in his opening statement.
Last edited:
Okokokokokok ..... maybe I thought up a better, clearer and more concise way to ask my question.
If two woofers are driven in series, does the first one modulate the signal to the second one?
" Modulation: noun (Electronics) The variation of a property of an electromagnetic wave or signal, such as its amplitude, frequency, or phase. "
Better now? Yes? No? 🙂 jj
If two woofers are driven in series, does the first one modulate the signal to the second one?
" Modulation: noun (Electronics) The variation of a property of an electromagnetic wave or signal, such as its amplitude, frequency, or phase. "
Better now? Yes? No? 🙂 jj
I'll attempt to clarify just one of the things I think has only been implied so far.
The connection between the drivers will be at half the Voltage as seen across the terminals. Despite the drivers' varying behaviour and impedance, they are also the same as each other so will split evenly. Given that this middle point is at a fixed relative Voltage, as far as 'unexpected' influence is concerned it is as if the other driver does not exist.
The connection between the drivers will be at half the Voltage as seen across the terminals. Despite the drivers' varying behaviour and impedance, they are also the same as each other so will split evenly. Given that this middle point is at a fixed relative Voltage, as far as 'unexpected' influence is concerned it is as if the other driver does not exist.
Or does the second one modulate the first one?
Who is on first?
A different thought: is the current in each driver the same or different? Is that important? Insightful?