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Peter Wieck[_2_] Peter Wieck[_2_] is offline
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Posts: 137
Default Horizontal vs. Vertical bi-amping

LOTS of Kool-Aid being dispensed here. But lets look at a little bit of the=
math, if possible. Not knowing whether these assumptions are true or not, =
let's just put them out the

1) Bi-Amping will deliver more total current to the bass drivers than if th=
ey were powered from one amp.=20

2) In the article cited, a statement was made that there was far more energ=
y in the bass than in the treble. Which seems to mitigate towards bi-amping=
..=20

3) There is some stuff within the article and elsewhere that suggests that =
multiple power-supplies are better than a single power-supply of the same a=
ggregate capacity.=20

So:=20

a) Let us take the case of two 30-watt amps vs. one 60 watt amp.=20
b) Let us take the "far more" to be 2 x current required.=20
c) Let us allow the Peak-to-Average to be 20 dB. Somewhere between Chamber =
Orchestra and Full Orchestra.=20
d) let us make the speakers at 85dB - as Maggies were cited in the article.
e) Let us assume that the source used is well recorded and well mastered.=
=20
f) Let us assume that the electronics are of excellent quality and fully fu=
nctional. =20

The Mid/Tweet will be capped at 100dB without clipping.=20
If the Mid-Tweet is making 98dB at 20 watts, and the bass needs 2 x the cur=
rent, the bass will be starving at the available 30 watts.=20

Whereas a single 60-watt amp will be able to divide the current at a 2:1 ba=
sis - 40 watts to the bass, 20 watts to the mid/tweet.=20

Add these discrepancies to the Saint-Saens Organ Symphony where the P/A is =
30 dB (if properly recorded) and bi-amping this way just will not work (nor=
will the fairly anemic single 60).=20

The only way this works, horizontal or vertical is if both amps are capable=
of driving the entirety of the speaker independently. Or the amps are diff=
erent in capacity but chosen to handle the differing loads. Either is fine,=
and either is practical, but the utter, complete and irredeemable BS about=
"power supplies" and such is neither.=20

Now, on the practicalities of horizontal vs. vertical - I have the capacity=
to do both, using up to four (4) theoretically identical amps. I will tell=
you by direct experience that four amps adding up to the same wattage as m=
y single brute-force power amp does not compare to that single amp. Brute h=
as the capacity to send whatever is needed to whatever section of the speak=
er (Maggies) that needs it at levels approaching the absurd, and handle tra=
nsients of up to 120 dB without breathing hard, the four smaller units cann=
ot do this.=20

On bi-wiring, I use 12-gauge 19-strand THHN wire twisted in a drill to abou=
t 6 turns per foot. Runs are about 10 feet or so. Seems sufficiently robust=
not to need bi-wiring. And at ~US$110 per 500' (250' paired) with tax and =
shipping, not so terribly expensive, either. With the additional virtue of =
being able to be pulled around corners and across abrasive surfaces without=
damage.=20

Peter Wieck
Melrose Park, PA=20

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~misfit~[_3_] ~misfit~[_3_] is offline
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Posts: 96
Default Horizontal vs. Vertical bi-amping

Once upon a time on usenet Peter Wieck wrote:
LOTS of Kool-Aid being dispensed here. But lets look at a little bit
of the math, if possible. Not knowing whether these assumptions are
true or not, let's just put them out the

1) Bi-Amping will deliver more total current to the bass drivers than
if they were powered from one amp.

2) In the article cited, a statement was made that there was far more
energy in the bass than in the treble. Which seems to mitigate
towards bi-amping.

3) There is some stuff within the article and elsewhere that suggests
that multiple power-supplies are better than a single power-supply of
the same aggregate capacity.

So:

a) Let us take the case of two 30-watt amps vs. one 60 watt amp.
b) Let us take the "far more" to be 2 x current required.
c) Let us allow the Peak-to-Average to be 20 dB. Somewhere between
Chamber Orchestra and Full Orchestra.
d) let us make the speakers at 85dB - as Maggies were cited in the
article.
e) Let us assume that the source used is well recorded and well
mastered.
f) Let us assume that the electronics are of excellent quality and
fully functional.

The Mid/Tweet will be capped at 100dB without clipping.
If the Mid-Tweet is making 98dB at 20 watts, and the bass needs 2 x
the current, the bass will be starving at the available 30 watts.

Whereas a single 60-watt amp will be able to divide the current at a
2:1 basis - 40 watts to the bass, 20 watts to the mid/tweet.

Add these discrepancies to the Saint-Saens Organ Symphony where the
P/A is 30 dB (if properly recorded) and bi-amping this way just will
not work (nor will the fairly anemic single 60).

The only way this works, horizontal or vertical is if both amps are
capable of driving the entirety of the speaker independently. Or the
amps are different in capacity but chosen to handle the differing
loads. Either is fine, and either is practical, but the utter,
complete and irredeemable BS about "power supplies" and such is
neither.

Now, on the practicalities of horizontal vs. vertical - I have the
capacity to do both, using up to four (4) theoretically identical
amps. I will tell you by direct experience that four amps adding up
to the same wattage as my single brute-force power amp does not
compare to that single amp. Brute has the capacity to send whatever
is needed to whatever section of the speaker (Maggies) that needs it
at levels approaching the absurd, and handle transients of up to 120
dB without breathing hard, the four smaller units cannot do this.

On bi-wiring, I use 12-gauge 19-strand THHN wire twisted in a drill
to about 6 turns per foot. Runs are about 10 feet or so. Seems
sufficiently robust not to need bi-wiring. And at ~US$110 per 500'
(250' paired) with tax and shipping, not so terribly expensive,
either. With the additional virtue of being able to be pulled around
corners and across abrasive surfaces without damage.

Peter Wieck
Melrose Park, PA


Thanks for writing that Peter.
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)


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