"Dick Pierce" wrote in message
om
"Arny Krueger" wrote in message
...
"Tim Padrick" wrote in message


An inductor in parallel with a tweeter, without a series capacitor,
would be seen by the amp as a short at low frequencies. A cap in
series with a woofer would roll off the low frequencies.

Agreed, and that leaves some non-simple problems to solve.

No it doesn't.


Please see my post from 8:23 EST this morning.

(Dick Pierce) wrote in message . com...
"Tim Padrick" wrote in message ...
Not so. In a series-pass crossover, the inductor would be in parallel
with the tweeter and the capacitor in series with the woofer. Two
SPICE files indicate the topological differences. First, the more
common parallel model (assume MyWoofer and MyTweeter are both
appropriate Spice sub circuit models of the woofer and tweeter, and
ignore the fact that the values may or may not be appropriate):

* Parallel crossover net list
Vin 1 0 AC SIN 1.0 0.0

Lwoof 1 2 1MH
Xwoof 2 0 MyWoofer

Ctweet 1 3 8UF
XTweet 3 0 MyTweeter

Now, the same as a series-pass model:

* Series crossover net list
Vin 1 0 AC SIN 1.0 0.0

Cwoof 1 2 8UF
Xwoof 1 2 MyWoofer

LTweet 2 0 1MH
XTweet 2 0 MyTweeter


An inductor in parallel with a tweeter, without a series
capacitor, would be seen by the amp as a short at low
frequencies. A cap in series with a woofer would roll off
the low frequencies.

Too bad you didn't try to understand or analyze the circuit.

If you were to put JUST a tweeter and JUST an inductor in parallel
across an amp, you'd be right, but that's VERY clearly, from the
topology above, NOT what is happening. You cannot look at a circuit
and simpy pick little pieces of it and expect a quick analysis based
on one piece to give you a coherent picture of the whole. Let's, in
fact, do a more complete analysis and see what is REALLY happening

We'll make some simplifying assumption just to make the analysis
easier: we'll replace XWoofer and XTweeter with resistive loads
RWoofer and RTweeter.

Start at frequencies well below the crossover point. At these
frequencies the impedance of shunt capacitor CWoof is very high,
and that of the shunt inductor LTweet is very low. As a result,
the current flows through the woofer leg (RWoofer) and through
the inductor LTweet) And the amplifier sees, essentially, the
woofer as the load.

Now, at high frequencies well ABOVE the crossover point, the
impedance of the shunt capacitor CWoof is very low and that of
the shunt inductor LTweet is very high. As a result, the current
flows through the shunt capacitor (CWoofer), bypassing the woofer
and flowing through the tweeter leg. And the amplifier sees, essentially,
the tweeter as the load.

Around the crossover, the impedance of the two shunt reactances
LTweet and CWoof) are about the same, and are also about the same
as the impedances of the woofer and tweeter (assuming we don't pick
values out of thin air, like I did). In such a condition, equal
amounts of the current flow through each leg of the mesh, meaning
the power to the woofer and tweeter are about the same. And the load
seen by the amplifier is the parallel combination of the woofer mesh
and tweeter mesh.

Contrary to your analysis at NO point does the amplifier EVER see
a short circuit.

Let's in fact do a more precise analysis. I have adjusted the
values to something a bit more practical, aiming for a 1 kHz
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

Now, here's the output response across the woofer terminals
and the tweeter terminals, plotted every 1/3 octave:

Frequency Woofer Tweeter
Response Response
---------- -------- --------
20 Hz 0.0 dB -36.1 dB
25.2 0.0 -34.1
31.7 0.0 -32.1
40 0.0 -30.1
50.4 0.0 -28
63.5 0.0 -26
80 0.0 -24
101 0.0 -22
127 0.0 -19.9
160 0.0 -17.9
202 0.0 -15.8
254 0.0 -13.7
320 0.0 -11.6
403 0.0 -9.4
508 -0.1 -7.3
640 -0.4 -5.2
806 -0.9 -3.3
1020 -1.9 -1.8
1280 -3.4 -0.9
1610 -5.3 -0.3
2030 -7.4 -0.1
2560 -9.6 -0.0
3230 -11.8 0.0
4060 -13.9 0.0
5120 -16 0.0
6450 -18.1 0.0
8130 -20.1 0.0
10200 -22.1 0.0
12900 -24.2 0.0
16300 -26.2 0.0
20500 -28.2 0.0

As you can see, the response problems you predict simply do not
happen.

Now, as to the assertion of there being a "short circuit" across the
amplifier, let's look at the impedance:

Frequency Impedance
---------- ---------
20 Hz 8 Ohms
25.2 8
31.7 7.99
40 7.99
50.4 7.98
63.5 7.97
80 7.96
101 7.93
127 7.89
160 7.83
202 7.74
254 7.61
320 7.41
403 7.16
508 6.84
640 6.51
806 6.25
1020 6.15
1280 6.26
1610 6.53
2030 6.87
2560 7.18
3230 7.43
4060 7.62
5120 7.75
6450 7.84
8130 7.9
10200 7.93
12900 7.96
16300 7.97
20500 7.98

At no point does the impedance EVER drop below 6 ohms. Hardly a short
as you claim. Let's even look at DC, where the inductor impedance is
0 and the capacitor impedance is infinite: the imepdance of the total
cricuit is that of the woofer. At infinite frequency, where the
impedance of the capacitor is 0 and the inductor is infinite, the
impedance is that of the tweeter.


Arny:

Mybe it would help the discussion if I included a "picture" of the
actual crossover. I sent a drawing to Greg Dunn, and this is the
response he kindly sent back to me. (I don't have a clue as to how to
share a drawing through the newsgroup - any ideas??) Here's what Greg
had to say.......

"A brief analysis of the crossover:

The capacitor is in series with the tweeter no matter what position
the switch is in; the three positions just select varying degrees of
attentuation for the highs.

The inductor in series with the 15 ohm resistor is a peaking network
which raises the output of the tweeter at the frequency of choice --
but only when the attenuator is set to a level other than "max". I
suspect this is to give a bit of a "loudness" contour so that the
balance of the speaker is maintained when the highs are turned down.

Now the woofer. There is absolutely no attenuation on the woofer at
all, no matter what the position of the attenuator, nor the values of
the components. This is in keeping with what I'd expect from the SEAS
design; normally only the tweeter needs to be protected from extreme
frequencies reaching its voice coil. The woofer is quite safe at
higher frequencies, but the tweeter needs protection from lf/dc due to
the small wire and minimal heat dissipation. Wiring the woofer and
tweeter in reverse phase from each other would affect the midrange,
but not the low end."

Pete

(Dick Pierce) wrote in message . com...
"Tim Padrick" wrote in message ...
Not so. In a series-pass crossover, the inductor would be in parallel
with the tweeter and the capacitor in series with the woofer. Two
SPICE files indicate the topological differences. First, the more
common parallel model (assume MyWoofer and MyTweeter are both
appropriate Spice sub circuit models of the woofer and tweeter, and
ignore the fact that the values may or may not be appropriate):

* Parallel crossover net list
Vin 1 0 AC SIN 1.0 0.0

Lwoof 1 2 1MH
Xwoof 2 0 MyWoofer

Ctweet 1 3 8UF
XTweet 3 0 MyTweeter

Now, the same as a series-pass model:

* Series crossover net list
Vin 1 0 AC SIN 1.0 0.0

Cwoof 1 2 8UF
Xwoof 1 2 MyWoofer

LTweet 2 0 1MH
XTweet 2 0 MyTweeter


An inductor in parallel with a tweeter, without a series
capacitor, would be seen by the amp as a short at low
frequencies. A cap in series with a woofer would roll off
the low frequencies.

Too bad you didn't try to understand or analyze the circuit.

If you were to put JUST a tweeter and JUST an inductor in parallel
across an amp, you'd be right, but that's VERY clearly, from the
topology above, NOT what is happening. You cannot look at a circuit
and simpy pick little pieces of it and expect a quick analysis based
on one piece to give you a coherent picture of the whole. Let's, in
fact, do a more complete analysis and see what is REALLY happening

We'll make some simplifying assumption just to make the analysis
easier: we'll replace XWoofer and XTweeter with resistive loads
RWoofer and RTweeter.

Start at frequencies well below the crossover point. At these
frequencies the impedance of shunt capacitor CWoof is very high,
and that of the shunt inductor LTweet is very low. As a result,
the current flows through the woofer leg (RWoofer) and through
the inductor LTweet) And the amplifier sees, essentially, the
woofer as the load.

Now, at high frequencies well ABOVE the crossover point, the
impedance of the shunt capacitor CWoof is very low and that of
the shunt inductor LTweet is very high. As a result, the current
flows through the shunt capacitor (CWoofer), bypassing the woofer
and flowing through the tweeter leg. And the amplifier sees, essentially,
the tweeter as the load.

Around the crossover, the impedance of the two shunt reactances
LTweet and CWoof) are about the same, and are also about the same
as the impedances of the woofer and tweeter (assuming we don't pick
values out of thin air, like I did). In such a condition, equal
amounts of the current flow through each leg of the mesh, meaning
the power to the woofer and tweeter are about the same. And the load
seen by the amplifier is the parallel combination of the woofer mesh
and tweeter mesh.

Contrary to your analysis at NO point does the amplifier EVER see
a short circuit.

Let's in fact do a more precise analysis. I have adjusted the
values to something a bit more practical, aiming for a 1 kHz
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

Now, here's the output response across the woofer terminals
and the tweeter terminals, plotted every 1/3 octave:

Frequency Woofer Tweeter
Response Response
---------- -------- --------
20 Hz 0.0 dB -36.1 dB
25.2 0.0 -34.1
31.7 0.0 -32.1
40 0.0 -30.1
50.4 0.0 -28
63.5 0.0 -26
80 0.0 -24
101 0.0 -22
127 0.0 -19.9
160 0.0 -17.9
202 0.0 -15.8
254 0.0 -13.7
320 0.0 -11.6
403 0.0 -9.4
508 -0.1 -7.3
640 -0.4 -5.2
806 -0.9 -3.3
1020 -1.9 -1.8
1280 -3.4 -0.9
1610 -5.3 -0.3
2030 -7.4 -0.1
2560 -9.6 -0.0
3230 -11.8 0.0
4060 -13.9 0.0
5120 -16 0.0
6450 -18.1 0.0
8130 -20.1 0.0
10200 -22.1 0.0
12900 -24.2 0.0
16300 -26.2 0.0
20500 -28.2 0.0

As you can see, the response problems you predict simply do not
happen.

Now, as to the assertion of there being a "short circuit" across the
amplifier, let's look at the impedance:

Frequency Impedance
---------- ---------
20 Hz 8 Ohms
25.2 8
31.7 7.99
40 7.99
50.4 7.98
63.5 7.97
80 7.96
101 7.93
127 7.89
160 7.83
202 7.74
254 7.61
320 7.41
403 7.16
508 6.84
640 6.51
806 6.25
1020 6.15
1280 6.26
1610 6.53
2030 6.87
2560 7.18
3230 7.43
4060 7.62
5120 7.75
6450 7.84
8130 7.9
10200 7.93
12900 7.96
16300 7.97
20500 7.98

At no point does the impedance EVER drop below 6 ohms. Hardly a short
as you claim. Let's even look at DC, where the inductor impedance is
0 and the capacitor impedance is infinite: the imepdance of the total
cricuit is that of the woofer. At infinite frequency, where the
impedance of the capacitor is 0 and the inductor is infinite, the
impedance is that of the tweeter.


Arny:

Mybe it would help the discussion if I included a "picture" of the
actual crossover. I sent a drawing to Greg Dunn, and this is the
response he kindly sent back to me. (I don't have a clue as to how to
share a drawing through the newsgroup - any ideas??) Here's what Greg
had to say.......

"A brief analysis of the crossover:

The capacitor is in series with the tweeter no matter what position
the switch is in; the three positions just select varying degrees of
attentuation for the highs.

The inductor in series with the 15 ohm resistor is a peaking network
which raises the output of the tweeter at the frequency of choice --
but only when the attenuator is set to a level other than "max". I
suspect this is to give a bit of a "loudness" contour so that the
balance of the speaker is maintained when the highs are turned down.

Now the woofer. There is absolutely no attenuation on the woofer at
all, no matter what the position of the attenuator, nor the values of
the components. This is in keeping with what I'd expect from the SEAS
design; normally only the tweeter needs to be protected from extreme
frequencies reaching its voice coil. The woofer is quite safe at
higher frequencies, but the tweeter needs protection from lf/dc due to
the small wire and minimal heat dissipation. Wiring the woofer and
tweeter in reverse phase from each other would affect the midrange,
but not the low end."

Pete

(Dick Pierce) wrote in message . com...
"Tim Padrick" wrote in message ...
Not so. In a series-pass crossover, the inductor would be in parallel
with the tweeter and the capacitor in series with the woofer. Two
SPICE files indicate the topological differences. First, the more
common parallel model (assume MyWoofer and MyTweeter are both
appropriate Spice sub circuit models of the woofer and tweeter, and
ignore the fact that the values may or may not be appropriate):

* Parallel crossover net list
Vin 1 0 AC SIN 1.0 0.0

Lwoof 1 2 1MH
Xwoof 2 0 MyWoofer

Ctweet 1 3 8UF
XTweet 3 0 MyTweeter

Now, the same as a series-pass model:

* Series crossover net list
Vin 1 0 AC SIN 1.0 0.0

Cwoof 1 2 8UF
Xwoof 1 2 MyWoofer

LTweet 2 0 1MH
XTweet 2 0 MyTweeter


An inductor in parallel with a tweeter, without a series
capacitor, would be seen by the amp as a short at low
frequencies. A cap in series with a woofer would roll off
the low frequencies.

Too bad you didn't try to understand or analyze the circuit.

If you were to put JUST a tweeter and JUST an inductor in parallel
across an amp, you'd be right, but that's VERY clearly, from the
topology above, NOT what is happening. You cannot look at a circuit
and simpy pick little pieces of it and expect a quick analysis based
on one piece to give you a coherent picture of the whole. Let's, in
fact, do a more complete analysis and see what is REALLY happening

We'll make some simplifying assumption just to make the analysis
easier: we'll replace XWoofer and XTweeter with resistive loads
RWoofer and RTweeter.

Start at frequencies well below the crossover point. At these
frequencies the impedance of shunt capacitor CWoof is very high,
and that of the shunt inductor LTweet is very low. As a result,
the current flows through the woofer leg (RWoofer) and through
the inductor LTweet) And the amplifier sees, essentially, the
woofer as the load.

Now, at high frequencies well ABOVE the crossover point, the
impedance of the shunt capacitor CWoof is very low and that of
the shunt inductor LTweet is very high. As a result, the current
flows through the shunt capacitor (CWoofer), bypassing the woofer
and flowing through the tweeter leg. And the amplifier sees, essentially,
the tweeter as the load.

Around the crossover, the impedance of the two shunt reactances
LTweet and CWoof) are about the same, and are also about the same
as the impedances of the woofer and tweeter (assuming we don't pick
values out of thin air, like I did). In such a condition, equal
amounts of the current flow through each leg of the mesh, meaning
the power to the woofer and tweeter are about the same. And the load
seen by the amplifier is the parallel combination of the woofer mesh
and tweeter mesh.

Contrary to your analysis at NO point does the amplifier EVER see
a short circuit.

Let's in fact do a more precise analysis. I have adjusted the
values to something a bit more practical, aiming for a 1 kHz
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

Now, here's the output response across the woofer terminals
and the tweeter terminals, plotted every 1/3 octave:

Frequency Woofer Tweeter
Response Response
---------- -------- --------
20 Hz 0.0 dB -36.1 dB
25.2 0.0 -34.1
31.7 0.0 -32.1
40 0.0 -30.1
50.4 0.0 -28
63.5 0.0 -26
80 0.0 -24
101 0.0 -22
127 0.0 -19.9
160 0.0 -17.9
202 0.0 -15.8
254 0.0 -13.7
320 0.0 -11.6
403 0.0 -9.4
508 -0.1 -7.3
640 -0.4 -5.2
806 -0.9 -3.3
1020 -1.9 -1.8
1280 -3.4 -0.9
1610 -5.3 -0.3
2030 -7.4 -0.1
2560 -9.6 -0.0
3230 -11.8 0.0
4060 -13.9 0.0
5120 -16 0.0
6450 -18.1 0.0
8130 -20.1 0.0
10200 -22.1 0.0
12900 -24.2 0.0
16300 -26.2 0.0
20500 -28.2 0.0

As you can see, the response problems you predict simply do not
happen.

Now, as to the assertion of there being a "short circuit" across the
amplifier, let's look at the impedance:

Frequency Impedance
---------- ---------
20 Hz 8 Ohms
25.2 8
31.7 7.99
40 7.99
50.4 7.98
63.5 7.97
80 7.96
101 7.93
127 7.89
160 7.83
202 7.74
254 7.61
320 7.41
403 7.16
508 6.84
640 6.51
806 6.25
1020 6.15
1280 6.26
1610 6.53
2030 6.87
2560 7.18
3230 7.43
4060 7.62
5120 7.75
6450 7.84
8130 7.9
10200 7.93
12900 7.96
16300 7.97
20500 7.98

At no point does the impedance EVER drop below 6 ohms. Hardly a short
as you claim. Let's even look at DC, where the inductor impedance is
0 and the capacitor impedance is infinite: the imepdance of the total
cricuit is that of the woofer. At infinite frequency, where the
impedance of the capacitor is 0 and the inductor is infinite, the
impedance is that of the tweeter.


Arny:

Mybe it would help the discussion if I included a "picture" of the
actual crossover. I sent a drawing to Greg Dunn, and this is the
response he kindly sent back to me. (I don't have a clue as to how to
share a drawing through the newsgroup - any ideas??) Here's what Greg
had to say.......

"A brief analysis of the crossover:

The capacitor is in series with the tweeter no matter what position
the switch is in; the three positions just select varying degrees of
attentuation for the highs.

The inductor in series with the 15 ohm resistor is a peaking network
which raises the output of the tweeter at the frequency of choice --
but only when the attenuator is set to a level other than "max". I
suspect this is to give a bit of a "loudness" contour so that the
balance of the speaker is maintained when the highs are turned down.

Now the woofer. There is absolutely no attenuation on the woofer at
all, no matter what the position of the attenuator, nor the values of
the components. This is in keeping with what I'd expect from the SEAS
design; normally only the tweeter needs to be protected from extreme
frequencies reaching its voice coil. The woofer is quite safe at
higher frequencies, but the tweeter needs protection from lf/dc due to
the small wire and minimal heat dissipation. Wiring the woofer and
tweeter in reverse phase from each other would affect the midrange,
but not the low end."

Pete

(Dick Pierce) wrote in message . com...
"Tim Padrick" wrote in message ...
Not so. In a series-pass crossover, the inductor would be in parallel
with the tweeter and the capacitor in series with the woofer. Two
SPICE files indicate the topological differences. First, the more
common parallel model (assume MyWoofer and MyTweeter are both
appropriate Spice sub circuit models of the woofer and tweeter, and
ignore the fact that the values may or may not be appropriate):

* Parallel crossover net list
Vin 1 0 AC SIN 1.0 0.0

Lwoof 1 2 1MH
Xwoof 2 0 MyWoofer

Ctweet 1 3 8UF
XTweet 3 0 MyTweeter

Now, the same as a series-pass model:

* Series crossover net list
Vin 1 0 AC SIN 1.0 0.0

Cwoof 1 2 8UF
Xwoof 1 2 MyWoofer

LTweet 2 0 1MH
XTweet 2 0 MyTweeter


An inductor in parallel with a tweeter, without a series
capacitor, would be seen by the amp as a short at low
frequencies. A cap in series with a woofer would roll off
the low frequencies.

Too bad you didn't try to understand or analyze the circuit.

If you were to put JUST a tweeter and JUST an inductor in parallel
across an amp, you'd be right, but that's VERY clearly, from the
topology above, NOT what is happening. You cannot look at a circuit
and simpy pick little pieces of it and expect a quick analysis based
on one piece to give you a coherent picture of the whole. Let's, in
fact, do a more complete analysis and see what is REALLY happening

We'll make some simplifying assumption just to make the analysis
easier: we'll replace XWoofer and XTweeter with resistive loads
RWoofer and RTweeter.

Start at frequencies well below the crossover point. At these
frequencies the impedance of shunt capacitor CWoof is very high,
and that of the shunt inductor LTweet is very low. As a result,
the current flows through the woofer leg (RWoofer) and through
the inductor LTweet) And the amplifier sees, essentially, the
woofer as the load.

Now, at high frequencies well ABOVE the crossover point, the
impedance of the shunt capacitor CWoof is very low and that of
the shunt inductor LTweet is very high. As a result, the current
flows through the shunt capacitor (CWoofer), bypassing the woofer
and flowing through the tweeter leg. And the amplifier sees, essentially,
the tweeter as the load.

Around the crossover, the impedance of the two shunt reactances
LTweet and CWoof) are about the same, and are also about the same
as the impedances of the woofer and tweeter (assuming we don't pick
values out of thin air, like I did). In such a condition, equal
amounts of the current flow through each leg of the mesh, meaning
the power to the woofer and tweeter are about the same. And the load
seen by the amplifier is the parallel combination of the woofer mesh
and tweeter mesh.

Contrary to your analysis at NO point does the amplifier EVER see
a short circuit.

Let's in fact do a more precise analysis. I have adjusted the
values to something a bit more practical, aiming for a 1 kHz
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

Now, here's the output response across the woofer terminals
and the tweeter terminals, plotted every 1/3 octave:

Frequency Woofer Tweeter
Response Response
---------- -------- --------
20 Hz 0.0 dB -36.1 dB
25.2 0.0 -34.1
31.7 0.0 -32.1
40 0.0 -30.1
50.4 0.0 -28
63.5 0.0 -26
80 0.0 -24
101 0.0 -22
127 0.0 -19.9
160 0.0 -17.9
202 0.0 -15.8
254 0.0 -13.7
320 0.0 -11.6
403 0.0 -9.4
508 -0.1 -7.3
640 -0.4 -5.2
806 -0.9 -3.3
1020 -1.9 -1.8
1280 -3.4 -0.9
1610 -5.3 -0.3
2030 -7.4 -0.1
2560 -9.6 -0.0
3230 -11.8 0.0
4060 -13.9 0.0
5120 -16 0.0
6450 -18.1 0.0
8130 -20.1 0.0
10200 -22.1 0.0
12900 -24.2 0.0
16300 -26.2 0.0
20500 -28.2 0.0

As you can see, the response problems you predict simply do not
happen.

Now, as to the assertion of there being a "short circuit" across the
amplifier, let's look at the impedance:

Frequency Impedance
---------- ---------
20 Hz 8 Ohms
25.2 8
31.7 7.99
40 7.99
50.4 7.98
63.5 7.97
80 7.96
101 7.93
127 7.89
160 7.83
202 7.74
254 7.61
320 7.41
403 7.16
508 6.84
640 6.51
806 6.25
1020 6.15
1280 6.26
1610 6.53
2030 6.87
2560 7.18
3230 7.43
4060 7.62
5120 7.75
6450 7.84
8130 7.9
10200 7.93
12900 7.96
16300 7.97
20500 7.98

At no point does the impedance EVER drop below 6 ohms. Hardly a short
as you claim. Let's even look at DC, where the inductor impedance is
0 and the capacitor impedance is infinite: the imepdance of the total
cricuit is that of the woofer. At infinite frequency, where the
impedance of the capacitor is 0 and the inductor is infinite, the
impedance is that of the tweeter.


Arny:

Mybe it would help the discussion if I included a "picture" of the
actual crossover. I sent a drawing to Greg Dunn, and this is the
response he kindly sent back to me. (I don't have a clue as to how to
share a drawing through the newsgroup - any ideas??) Here's what Greg
had to say.......

"A brief analysis of the crossover:

The capacitor is in series with the tweeter no matter what position
the switch is in; the three positions just select varying degrees of
attentuation for the highs.

The inductor in series with the 15 ohm resistor is a peaking network
which raises the output of the tweeter at the frequency of choice --
but only when the attenuator is set to a level other than "max". I
suspect this is to give a bit of a "loudness" contour so that the
balance of the speaker is maintained when the highs are turned down.

Now the woofer. There is absolutely no attenuation on the woofer at
all, no matter what the position of the attenuator, nor the values of
the components. This is in keeping with what I'd expect from the SEAS
design; normally only the tweeter needs to be protected from extreme
frequencies reaching its voice coil. The woofer is quite safe at
higher frequencies, but the tweeter needs protection from lf/dc due to
the small wire and minimal heat dissipation. Wiring the woofer and
tweeter in reverse phase from each other would affect the midrange,
but not the low end."

Pete

"Pete Snyder" wrote in message

Arny:

Mybe it would help the discussion if I included a "picture" of the
actual crossover.

Thanks but it is not necesary. I'm not the guy with the A-25 and I finally
got Dick Pierce's point.

If I want to look at an A25 crossover I would drop over my good friend's
house. He uses two of them on his basement test bench. I'm a bit more
modern - my test bench speakers are Paradigm Phantoms.

"Pete Snyder" wrote in message

Arny:

Mybe it would help the discussion if I included a "picture" of the
actual crossover.

Thanks but it is not necesary. I'm not the guy with the A-25 and I finally
got Dick Pierce's point.

If I want to look at an A25 crossover I would drop over my good friend's
house. He uses two of them on his basement test bench. I'm a bit more
modern - my test bench speakers are Paradigm Phantoms.

"Pete Snyder" wrote in message

Arny:

Mybe it would help the discussion if I included a "picture" of the
actual crossover.

Thanks but it is not necesary. I'm not the guy with the A-25 and I finally
got Dick Pierce's point.

If I want to look at an A25 crossover I would drop over my good friend's
house. He uses two of them on his basement test bench. I'm a bit more
modern - my test bench speakers are Paradigm Phantoms.

"Pete Snyder" wrote in message

Arny:

Mybe it would help the discussion if I included a "picture" of the
actual crossover.

Thanks but it is not necesary. I'm not the guy with the A-25 and I finally
got Dick Pierce's point.

If I want to look at an A25 crossover I would drop over my good friend's
house. He uses two of them on his basement test bench. I'm a bit more
modern - my test bench speakers are Paradigm Phantoms.

So is the capacitor shunting the woofer or in series with it? Can't be both.

(Dick Pierce) wrote in message . com...
"Tim Padrick" wrote in message ...
Not so. In a series-pass crossover, the inductor would be in parallel
with the tweeter and the capacitor in series with the woofer. Two
SPICE files indicate the topological differences. First, the more
common parallel model (assume MyWoofer and MyTweeter are both
appropriate Spice sub circuit models of the woofer and tweeter, and
ignore the fact that the values may or may not be appropriate):

* Parallel crossover net list
Vin 1 0 AC SIN 1.0 0.0

Lwoof 1 2 1MH
Xwoof 2 0 MyWoofer

Ctweet 1 3 8UF
XTweet 3 0 MyTweeter

Now, the same as a series-pass model:

* Series crossover net list
Vin 1 0 AC SIN 1.0 0.0

Cwoof 1 2 8UF
Xwoof 1 2 MyWoofer

LTweet 2 0 1MH
XTweet 2 0 MyTweeter


An inductor in parallel with a tweeter, without a series
capacitor, would be seen by the amp as a short at low
frequencies. A cap in series with a woofer would roll off
the low frequencies.

Too bad you didn't try to understand or analyze the circuit.

If you were to put JUST a tweeter and JUST an inductor in parallel
across an amp, you'd be right, but that's VERY clearly, from the
topology above, NOT what is happening. You cannot look at a circuit
and simpy pick little pieces of it and expect a quick analysis based
on one piece to give you a coherent picture of the whole. Let's, in
fact, do a more complete analysis and see what is REALLY happening

We'll make some simplifying assumption just to make the analysis
easier: we'll replace XWoofer and XTweeter with resistive loads
RWoofer and RTweeter.

Start at frequencies well below the crossover point. At these
frequencies the impedance of shunt capacitor CWoof is very high,
and that of the shunt inductor LTweet is very low. As a result,
the current flows through the woofer leg (RWoofer) and through
the inductor LTweet) And the amplifier sees, essentially, the
woofer as the load.

Now, at high frequencies well ABOVE the crossover point, the
impedance of the shunt capacitor CWoof is very low and that of
the shunt inductor LTweet is very high. As a result, the current
flows through the shunt capacitor (CWoofer), bypassing the woofer
and flowing through the tweeter leg. And the amplifier sees, essentially,
the tweeter as the load.

Around the crossover, the impedance of the two shunt reactances
LTweet and CWoof) are about the same, and are also about the same
as the impedances of the woofer and tweeter (assuming we don't pick
values out of thin air, like I did). In such a condition, equal
amounts of the current flow through each leg of the mesh, meaning
the power to the woofer and tweeter are about the same. And the load
seen by the amplifier is the parallel combination of the woofer mesh
and tweeter mesh.

Contrary to your analysis at NO point does the amplifier EVER see
a short circuit.

Let's in fact do a more precise analysis. I have adjusted the
values to something a bit more practical, aiming for a 1 kHz
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

Now, here's the output response across the woofer terminals
and the tweeter terminals, plotted every 1/3 octave:

Frequency Woofer Tweeter
Response Response
---------- -------- --------
20 Hz 0.0 dB -36.1 dB
25.2 0.0 -34.1
31.7 0.0 -32.1
40 0.0 -30.1
50.4 0.0 -28
63.5 0.0 -26
80 0.0 -24
101 0.0 -22
127 0.0 -19.9
160 0.0 -17.9
202 0.0 -15.8
254 0.0 -13.7
320 0.0 -11.6
403 0.0 -9.4
508 -0.1 -7.3
640 -0.4 -5.2
806 -0.9 -3.3
1020 -1.9 -1.8
1280 -3.4 -0.9
1610 -5.3 -0.3
2030 -7.4 -0.1
2560 -9.6 -0.0
3230 -11.8 0.0
4060 -13.9 0.0
5120 -16 0.0
6450 -18.1 0.0
8130 -20.1 0.0
10200 -22.1 0.0
12900 -24.2 0.0
16300 -26.2 0.0
20500 -28.2 0.0

As you can see, the response problems you predict simply do not
happen.

Now, as to the assertion of there being a "short circuit" across the
amplifier, let's look at the impedance:

Frequency Impedance
---------- ---------
20 Hz 8 Ohms
25.2 8
31.7 7.99
40 7.99
50.4 7.98
63.5 7.97
80 7.96
101 7.93
127 7.89
160 7.83
202 7.74
254 7.61
320 7.41
403 7.16
508 6.84
640 6.51
806 6.25
1020 6.15
1280 6.26
1610 6.53
2030 6.87
2560 7.18
3230 7.43
4060 7.62
5120 7.75
6450 7.84
8130 7.9
10200 7.93
12900 7.96
16300 7.97
20500 7.98

At no point does the impedance EVER drop below 6 ohms. Hardly a short
as you claim. Let's even look at DC, where the inductor impedance is
0 and the capacitor impedance is infinite: the imepdance of the total
cricuit is that of the woofer. At infinite frequency, where the
impedance of the capacitor is 0 and the inductor is infinite, the
impedance is that of the tweeter.

So is the capacitor shunting the woofer or in series with it? Can't be both.

(Dick Pierce) wrote in message . com...
"Tim Padrick" wrote in message ...
Not so. In a series-pass crossover, the inductor would be in parallel
with the tweeter and the capacitor in series with the woofer. Two
SPICE files indicate the topological differences. First, the more
common parallel model (assume MyWoofer and MyTweeter are both
appropriate Spice sub circuit models of the woofer and tweeter, and
ignore the fact that the values may or may not be appropriate):

* Parallel crossover net list
Vin 1 0 AC SIN 1.0 0.0

Lwoof 1 2 1MH
Xwoof 2 0 MyWoofer

Ctweet 1 3 8UF
XTweet 3 0 MyTweeter

Now, the same as a series-pass model:

* Series crossover net list
Vin 1 0 AC SIN 1.0 0.0

Cwoof 1 2 8UF
Xwoof 1 2 MyWoofer

LTweet 2 0 1MH
XTweet 2 0 MyTweeter


An inductor in parallel with a tweeter, without a series
capacitor, would be seen by the amp as a short at low
frequencies. A cap in series with a woofer would roll off
the low frequencies.

Too bad you didn't try to understand or analyze the circuit.

If you were to put JUST a tweeter and JUST an inductor in parallel
across an amp, you'd be right, but that's VERY clearly, from the
topology above, NOT what is happening. You cannot look at a circuit
and simpy pick little pieces of it and expect a quick analysis based
on one piece to give you a coherent picture of the whole. Let's, in
fact, do a more complete analysis and see what is REALLY happening

We'll make some simplifying assumption just to make the analysis
easier: we'll replace XWoofer and XTweeter with resistive loads
RWoofer and RTweeter.

Start at frequencies well below the crossover point. At these
frequencies the impedance of shunt capacitor CWoof is very high,
and that of the shunt inductor LTweet is very low. As a result,
the current flows through the woofer leg (RWoofer) and through
the inductor LTweet) And the amplifier sees, essentially, the
woofer as the load.

Now, at high frequencies well ABOVE the crossover point, the
impedance of the shunt capacitor CWoof is very low and that of
the shunt inductor LTweet is very high. As a result, the current
flows through the shunt capacitor (CWoofer), bypassing the woofer
and flowing through the tweeter leg. And the amplifier sees, essentially,
the tweeter as the load.

Around the crossover, the impedance of the two shunt reactances
LTweet and CWoof) are about the same, and are also about the same
as the impedances of the woofer and tweeter (assuming we don't pick
values out of thin air, like I did). In such a condition, equal
amounts of the current flow through each leg of the mesh, meaning
the power to the woofer and tweeter are about the same. And the load
seen by the amplifier is the parallel combination of the woofer mesh
and tweeter mesh.

Contrary to your analysis at NO point does the amplifier EVER see
a short circuit.

Let's in fact do a more precise analysis. I have adjusted the
values to something a bit more practical, aiming for a 1 kHz
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

Now, here's the output response across the woofer terminals
and the tweeter terminals, plotted every 1/3 octave:

Frequency Woofer Tweeter
Response Response
---------- -------- --------
20 Hz 0.0 dB -36.1 dB
25.2 0.0 -34.1
31.7 0.0 -32.1
40 0.0 -30.1
50.4 0.0 -28
63.5 0.0 -26
80 0.0 -24
101 0.0 -22
127 0.0 -19.9
160 0.0 -17.9
202 0.0 -15.8
254 0.0 -13.7
320 0.0 -11.6
403 0.0 -9.4
508 -0.1 -7.3
640 -0.4 -5.2
806 -0.9 -3.3
1020 -1.9 -1.8
1280 -3.4 -0.9
1610 -5.3 -0.3
2030 -7.4 -0.1
2560 -9.6 -0.0
3230 -11.8 0.0
4060 -13.9 0.0
5120 -16 0.0
6450 -18.1 0.0
8130 -20.1 0.0
10200 -22.1 0.0
12900 -24.2 0.0
16300 -26.2 0.0
20500 -28.2 0.0

As you can see, the response problems you predict simply do not
happen.

Now, as to the assertion of there being a "short circuit" across the
amplifier, let's look at the impedance:

Frequency Impedance
---------- ---------
20 Hz 8 Ohms
25.2 8
31.7 7.99
40 7.99
50.4 7.98
63.5 7.97
80 7.96
101 7.93
127 7.89
160 7.83
202 7.74
254 7.61
320 7.41
403 7.16
508 6.84
640 6.51
806 6.25
1020 6.15
1280 6.26
1610 6.53
2030 6.87
2560 7.18
3230 7.43
4060 7.62
5120 7.75
6450 7.84
8130 7.9
10200 7.93
12900 7.96
16300 7.97
20500 7.98

At no point does the impedance EVER drop below 6 ohms. Hardly a short
as you claim. Let's even look at DC, where the inductor impedance is
0 and the capacitor impedance is infinite: the imepdance of the total
cricuit is that of the woofer. At infinite frequency, where the
impedance of the capacitor is 0 and the inductor is infinite, the
impedance is that of the tweeter.

So is the capacitor shunting the woofer or in series with it? Can't be both.

(Dick Pierce) wrote in message . com...
"Tim Padrick" wrote in message ...
Not so. In a series-pass crossover, the inductor would be in parallel
with the tweeter and the capacitor in series with the woofer. Two
SPICE files indicate the topological differences. First, the more
common parallel model (assume MyWoofer and MyTweeter are both
appropriate Spice sub circuit models of the woofer and tweeter, and
ignore the fact that the values may or may not be appropriate):

* Parallel crossover net list
Vin 1 0 AC SIN 1.0 0.0

Lwoof 1 2 1MH
Xwoof 2 0 MyWoofer

Ctweet 1 3 8UF
XTweet 3 0 MyTweeter

Now, the same as a series-pass model:

* Series crossover net list
Vin 1 0 AC SIN 1.0 0.0

Cwoof 1 2 8UF
Xwoof 1 2 MyWoofer

LTweet 2 0 1MH
XTweet 2 0 MyTweeter


An inductor in parallel with a tweeter, without a series
capacitor, would be seen by the amp as a short at low
frequencies. A cap in series with a woofer would roll off
the low frequencies.

Too bad you didn't try to understand or analyze the circuit.

If you were to put JUST a tweeter and JUST an inductor in parallel
across an amp, you'd be right, but that's VERY clearly, from the
topology above, NOT what is happening. You cannot look at a circuit
and simpy pick little pieces of it and expect a quick analysis based
on one piece to give you a coherent picture of the whole. Let's, in
fact, do a more complete analysis and see what is REALLY happening

We'll make some simplifying assumption just to make the analysis
easier: we'll replace XWoofer and XTweeter with resistive loads
RWoofer and RTweeter.

Start at frequencies well below the crossover point. At these
frequencies the impedance of shunt capacitor CWoof is very high,
and that of the shunt inductor LTweet is very low. As a result,
the current flows through the woofer leg (RWoofer) and through
the inductor LTweet) And the amplifier sees, essentially, the
woofer as the load.

Now, at high frequencies well ABOVE the crossover point, the
impedance of the shunt capacitor CWoof is very low and that of
the shunt inductor LTweet is very high. As a result, the current
flows through the shunt capacitor (CWoofer), bypassing the woofer
and flowing through the tweeter leg. And the amplifier sees, essentially,
the tweeter as the load.

Around the crossover, the impedance of the two shunt reactances
LTweet and CWoof) are about the same, and are also about the same
as the impedances of the woofer and tweeter (assuming we don't pick
values out of thin air, like I did). In such a condition, equal
amounts of the current flow through each leg of the mesh, meaning
the power to the woofer and tweeter are about the same. And the load
seen by the amplifier is the parallel combination of the woofer mesh
and tweeter mesh.

Contrary to your analysis at NO point does the amplifier EVER see
a short circuit.

Let's in fact do a more precise analysis. I have adjusted the
values to something a bit more practical, aiming for a 1 kHz
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

Now, here's the output response across the woofer terminals
and the tweeter terminals, plotted every 1/3 octave:

Frequency Woofer Tweeter
Response Response
---------- -------- --------
20 Hz 0.0 dB -36.1 dB
25.2 0.0 -34.1
31.7 0.0 -32.1
40 0.0 -30.1
50.4 0.0 -28
63.5 0.0 -26
80 0.0 -24
101 0.0 -22
127 0.0 -19.9
160 0.0 -17.9
202 0.0 -15.8
254 0.0 -13.7
320 0.0 -11.6
403 0.0 -9.4
508 -0.1 -7.3
640 -0.4 -5.2
806 -0.9 -3.3
1020 -1.9 -1.8
1280 -3.4 -0.9
1610 -5.3 -0.3
2030 -7.4 -0.1
2560 -9.6 -0.0
3230 -11.8 0.0
4060 -13.9 0.0
5120 -16 0.0
6450 -18.1 0.0
8130 -20.1 0.0
10200 -22.1 0.0
12900 -24.2 0.0
16300 -26.2 0.0
20500 -28.2 0.0

As you can see, the response problems you predict simply do not
happen.

Now, as to the assertion of there being a "short circuit" across the
amplifier, let's look at the impedance:

Frequency Impedance
---------- ---------
20 Hz 8 Ohms
25.2 8
31.7 7.99
40 7.99
50.4 7.98
63.5 7.97
80 7.96
101 7.93
127 7.89
160 7.83
202 7.74
254 7.61
320 7.41
403 7.16
508 6.84
640 6.51
806 6.25
1020 6.15
1280 6.26
1610 6.53
2030 6.87
2560 7.18
3230 7.43
4060 7.62
5120 7.75
6450 7.84
8130 7.9
10200 7.93
12900 7.96
16300 7.97
20500 7.98

At no point does the impedance EVER drop below 6 ohms. Hardly a short
as you claim. Let's even look at DC, where the inductor impedance is
0 and the capacitor impedance is infinite: the imepdance of the total
cricuit is that of the woofer. At infinite frequency, where the
impedance of the capacitor is 0 and the inductor is infinite, the
impedance is that of the tweeter.

So is the capacitor shunting the woofer or in series with it? Can't be both.

(Dick Pierce) wrote in message . com...
"Tim Padrick" wrote in message ...
Not so. In a series-pass crossover, the inductor would be in parallel
with the tweeter and the capacitor in series with the woofer. Two
SPICE files indicate the topological differences. First, the more
common parallel model (assume MyWoofer and MyTweeter are both
appropriate Spice sub circuit models of the woofer and tweeter, and
ignore the fact that the values may or may not be appropriate):

* Parallel crossover net list
Vin 1 0 AC SIN 1.0 0.0

Lwoof 1 2 1MH
Xwoof 2 0 MyWoofer

Ctweet 1 3 8UF
XTweet 3 0 MyTweeter

Now, the same as a series-pass model:

* Series crossover net list
Vin 1 0 AC SIN 1.0 0.0

Cwoof 1 2 8UF
Xwoof 1 2 MyWoofer

LTweet 2 0 1MH
XTweet 2 0 MyTweeter


An inductor in parallel with a tweeter, without a series
capacitor, would be seen by the amp as a short at low
frequencies. A cap in series with a woofer would roll off
the low frequencies.

Too bad you didn't try to understand or analyze the circuit.

If you were to put JUST a tweeter and JUST an inductor in parallel
across an amp, you'd be right, but that's VERY clearly, from the
topology above, NOT what is happening. You cannot look at a circuit
and simpy pick little pieces of it and expect a quick analysis based
on one piece to give you a coherent picture of the whole. Let's, in
fact, do a more complete analysis and see what is REALLY happening

We'll make some simplifying assumption just to make the analysis
easier: we'll replace XWoofer and XTweeter with resistive loads
RWoofer and RTweeter.

Start at frequencies well below the crossover point. At these
frequencies the impedance of shunt capacitor CWoof is very high,
and that of the shunt inductor LTweet is very low. As a result,
the current flows through the woofer leg (RWoofer) and through
the inductor LTweet) And the amplifier sees, essentially, the
woofer as the load.

Now, at high frequencies well ABOVE the crossover point, the
impedance of the shunt capacitor CWoof is very low and that of
the shunt inductor LTweet is very high. As a result, the current
flows through the shunt capacitor (CWoofer), bypassing the woofer
and flowing through the tweeter leg. And the amplifier sees, essentially,
the tweeter as the load.

Around the crossover, the impedance of the two shunt reactances
LTweet and CWoof) are about the same, and are also about the same
as the impedances of the woofer and tweeter (assuming we don't pick
values out of thin air, like I did). In such a condition, equal
amounts of the current flow through each leg of the mesh, meaning
the power to the woofer and tweeter are about the same. And the load
seen by the amplifier is the parallel combination of the woofer mesh
and tweeter mesh.

Contrary to your analysis at NO point does the amplifier EVER see
a short circuit.

Let's in fact do a more precise analysis. I have adjusted the
values to something a bit more practical, aiming for a 1 kHz
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

Now, here's the output response across the woofer terminals
and the tweeter terminals, plotted every 1/3 octave:

Frequency Woofer Tweeter
Response Response
---------- -------- --------
20 Hz 0.0 dB -36.1 dB
25.2 0.0 -34.1
31.7 0.0 -32.1
40 0.0 -30.1
50.4 0.0 -28
63.5 0.0 -26
80 0.0 -24
101 0.0 -22
127 0.0 -19.9
160 0.0 -17.9
202 0.0 -15.8
254 0.0 -13.7
320 0.0 -11.6
403 0.0 -9.4
508 -0.1 -7.3
640 -0.4 -5.2
806 -0.9 -3.3
1020 -1.9 -1.8
1280 -3.4 -0.9
1610 -5.3 -0.3
2030 -7.4 -0.1
2560 -9.6 -0.0
3230 -11.8 0.0
4060 -13.9 0.0
5120 -16 0.0
6450 -18.1 0.0
8130 -20.1 0.0
10200 -22.1 0.0
12900 -24.2 0.0
16300 -26.2 0.0
20500 -28.2 0.0

As you can see, the response problems you predict simply do not
happen.

Now, as to the assertion of there being a "short circuit" across the
amplifier, let's look at the impedance:

Frequency Impedance
---------- ---------
20 Hz 8 Ohms
25.2 8
31.7 7.99
40 7.99
50.4 7.98
63.5 7.97
80 7.96
101 7.93
127 7.89
160 7.83
202 7.74
254 7.61
320 7.41
403 7.16
508 6.84
640 6.51
806 6.25
1020 6.15
1280 6.26
1610 6.53
2030 6.87
2560 7.18
3230 7.43
4060 7.62
5120 7.75
6450 7.84
8130 7.9
10200 7.93
12900 7.96
16300 7.97
20500 7.98

At no point does the impedance EVER drop below 6 ohms. Hardly a short
as you claim. Let's even look at DC, where the inductor impedance is
0 and the capacitor impedance is infinite: the imepdance of the total
cricuit is that of the woofer. At infinite frequency, where the
impedance of the capacitor is 0 and the inductor is infinite, the
impedance is that of the tweeter.

(unitron) wrote in message . com...
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

So is the capacitor shunting the woofer or in series with it?
Can't be both.

Did you take the time to actually read the information I provided?
Above is the netlist of the crossover topology I described. It's
pretty definite: CWoof, a 25 uF capacitor is connected between
nodes 1 and 2. So is the woofer. There's nothing in the netlist
that could possibly lead to ANY other conclusion than the capacitor
being in parallel with the woofer.

(unitron) wrote in message . com...
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

So is the capacitor shunting the woofer or in series with it?
Can't be both.

Did you take the time to actually read the information I provided?
Above is the netlist of the crossover topology I described. It's
pretty definite: CWoof, a 25 uF capacitor is connected between
nodes 1 and 2. So is the woofer. There's nothing in the netlist
that could possibly lead to ANY other conclusion than the capacitor
being in parallel with the woofer.

(unitron) wrote in message . com...
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

So is the capacitor shunting the woofer or in series with it?
Can't be both.

Did you take the time to actually read the information I provided?
Above is the netlist of the crossover topology I described. It's
pretty definite: CWoof, a 25 uF capacitor is connected between
nodes 1 and 2. So is the woofer. There's nothing in the netlist
that could possibly lead to ANY other conclusion than the capacitor
being in parallel with the woofer.

(unitron) wrote in message . com...
crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

So is the capacitor shunting the woofer or in series with it?
Can't be both.

Did you take the time to actually read the information I provided?
Above is the netlist of the crossover topology I described. It's
pretty definite: CWoof, a 25 uF capacitor is connected between
nodes 1 and 2. So is the woofer. There's nothing in the netlist
that could possibly lead to ANY other conclusion than the capacitor
being in parallel with the woofer.

Dick Pierce wrote:
(unitron) wrote in message . com...

crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

So is the capacitor shunting the woofer or in series with it?
Can't be both.


Did you take the time to actually read the information I provided?
Above is the netlist of the crossover topology I described. It's
pretty definite: CWoof, a 25 uF capacitor is connected between
nodes 1 and 2. So is the woofer. There's nothing in the netlist
that could possibly lead to ANY other conclusion than the capacitor
being in parallel with the woofer.


The serial networks are also described in the Philips boook:"Building
Hi-Fi Speaker Systems"(1977) which I found at a yard sale.For a 1st
order XVR the reactance values are the same in parallel/serial=R at the
XVR frequency but differ for 2nd order(butterworth) networks by a factor
of 2;the serial version uses L*2 & C/2 compared to its parallel counterpart.
In a MAR4/04 post I mentioned that the Woofer must have a series L
because of a 2nd order rollof at 1.5khz but this is incorrect since the
nearfield measurement is only valid to 500hx with a 10" WFR.

Dick Pierce wrote:
(unitron) wrote in message . com...

crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

So is the capacitor shunting the woofer or in series with it?
Can't be both.


Did you take the time to actually read the information I provided?
Above is the netlist of the crossover topology I described. It's
pretty definite: CWoof, a 25 uF capacitor is connected between
nodes 1 and 2. So is the woofer. There's nothing in the netlist
that could possibly lead to ANY other conclusion than the capacitor
being in parallel with the woofer.


The serial networks are also described in the Philips boook:"Building
Hi-Fi Speaker Systems"(1977) which I found at a yard sale.For a 1st
order XVR the reactance values are the same in parallel/serial=R at the
XVR frequency but differ for 2nd order(butterworth) networks by a factor
of 2;the serial version uses L*2 & C/2 compared to its parallel counterpart.
In a MAR4/04 post I mentioned that the Woofer must have a series L
because of a 2nd order rollof at 1.5khz but this is incorrect since the
nearfield measurement is only valid to 500hx with a 10" WFR.

Dick Pierce wrote:
(unitron) wrote in message . com...

crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

So is the capacitor shunting the woofer or in series with it?
Can't be both.


Did you take the time to actually read the information I provided?
Above is the netlist of the crossover topology I described. It's
pretty definite: CWoof, a 25 uF capacitor is connected between
nodes 1 and 2. So is the woofer. There's nothing in the netlist
that could possibly lead to ANY other conclusion than the capacitor
being in parallel with the woofer.


The serial networks are also described in the Philips boook:"Building
Hi-Fi Speaker Systems"(1977) which I found at a yard sale.For a 1st
order XVR the reactance values are the same in parallel/serial=R at the
XVR frequency but differ for 2nd order(butterworth) networks by a factor
of 2;the serial version uses L*2 & C/2 compared to its parallel counterpart.
In a MAR4/04 post I mentioned that the Woofer must have a series L
because of a 2nd order rollof at 1.5khz but this is incorrect since the
nearfield measurement is only valid to 500hx with a 10" WFR.

Dick Pierce wrote:
(unitron) wrote in message . com...

crossover. Here's the new circuit:

* Series crossover analysis
Vin 1 0 AC SIN 1.0 0.0

CWoof 1 2 25UF
RWoof 1 2 8

LTweet 2 0 1MH
RTweet 2 0 8

.AC OCT 3 20 20K
.PRINT AC VDB(1, 2) VDB(2,0)
.END

So is the capacitor shunting the woofer or in series with it?
Can't be both.


Did you take the time to actually read the information I provided?
Above is the netlist of the crossover topology I described. It's
pretty definite: CWoof, a 25 uF capacitor is connected between
nodes 1 and 2. So is the woofer. There's nothing in the netlist
that could possibly lead to ANY other conclusion than the capacitor
being in parallel with the woofer.


The serial networks are also described in the Philips boook:"Building
Hi-Fi Speaker Systems"(1977) which I found at a yard sale.For a 1st
order XVR the reactance values are the same in parallel/serial=R at the
XVR frequency but differ for 2nd order(butterworth) networks by a factor
of 2;the serial version uses L*2 & C/2 compared to its parallel counterpart.
In a MAR4/04 post I mentioned that the Woofer must have a series L
because of a 2nd order rollof at 1.5khz but this is incorrect since the
nearfield measurement is only valid to 500hx with a 10" WFR.