On another forum a chap says, he has been told, its ok to use a Quad power
amp (140 watts) with a Quad 405 (100 watts) with the same pre amplifier.


The idea being the 606 powers the bass and the 405 the tweeters.

Speakers being used Spendor s5e

Will this work ?

Said Quad told him they have the same "gain"


ta in advance

Dave

"Dave xxxx" wrote in message
k...
On another forum a chap says, he has been told, its ok to use a Quad power
amp (140 watts) with a Quad 405 (100 watts) with the same pre amplifier.


The idea being the 606 powers the bass and the 405 the tweeters.

Speakers being used Spendor s5e

Will this work ?

Said Quad told him they have the same "gain"


ta in advance

Dave


As they have the same gain, then they will put out the same power into the
same load. The 405, being a lower powered amplifier, will clip first, so if
you use passive biamping, that is, using the passive crossover in the
Spendors, the total output level will be limited by the clipping of the 405,
so you would have the same result as if you had two 405s. If you use an
active crossover between the pre-amp and the 'speaker, then you can take
advantage of the higher power of the 606 in the bass, and the lower power of
the 405 should be unimportant for the treble.

This shows the pointlessness of passive biamping, and the total power
available is the same as if you had used a single power amplifier, and you
only get the benefit of separate bass and treble amplification if you go
fully active with an electronic crossover.


Nevertheless, the advice you received from QUAD is correct.

S.

--
http://audiopages.googlepages.com

Dave xxxx wrote:
On another forum a chap says, he has been told, its ok to use a Quad power
amp (140 watts) with a Quad 405 (100 watts) with the same pre amplifier.


The idea being the 606 powers the bass and the 405 the tweeters.

Speakers being used Spendor s5e

Will this work ?

Quite pointless, as Serge said.

To get any benefit you need to rip out the passive crossover
and put one of these between the preamp and the power amps:
http://www.behringer.com/DCX2496/index.cfm?lang=eng

--
Eiron.

"Bob Latham" wrote in message


You are both correct from a simple electrical point of
view it is quite pointless. However, I might point out
that rightly or wrongly, probably a substantial majority
of people with an interest in Hi-Fi would say that
Bi-amped systems sound better

But this isn't really bi-amping. There are still passive crossovers, and
both amplifiers have to amplify the full signal.

and indeed to be
"pointless" the amplifiers would have to suffer zero load
issues.

Note that the impedance curve of this speaker shows that the tweeter
provides only a small fraction of the load on the power amplifier.

"Bob Latham" wrote in message

In article ,
Arny Krueger wrote:
"Bob Latham" wrote in message


You are both correct from a simple electrical point of
view it is quite pointless. However, I might point out
that rightly or wrongly, probably a substantial majority
of people with an interest in Hi-Fi would say that
Bi-amped systems sound better

But this isn't really bi-amping. There are still passive
crossovers, and both amplifiers have to amplify the full
signal.

Its not "active" certainly but it is what most would mean
by bi-amped.

Who is this "most"?

Most audio fanatics?

Bi-amped has traditionally meant, and means in most audio circles to this
day, active crossover, two power amps, two-way speaker system.

That a few naive audiophiles have been snookered into buying two amps to a
job that one amp can do as well, is an aberration.

and indeed to be
"pointless" the amplifiers would have to suffer zero
load issues.

Note that the impedance curve of this speaker shows that
the tweeter provides only a small fraction of the load
on the power amplifier.

Oh agreed completely. I suspect the pro bi-amp argument
would say that the heavy current load of the bass driver
is detrimental to the performance of the
amplifier/cable/tweeter performance.

That may sell on the salon sales floor, targeted at naive audiophiles that
have money burning a hole in their pockets.

Look a the vast majority of commercial products, not the world of sleezy
deals involving audio imbeciles. It is very hard to find commercial
bi-amped speakers that don't also have an active crossover.

"Arny Krueger" wrote in message
...
"Bob Latham" wrote in message

In article ,
Arny Krueger wrote:
"Bob Latham" wrote in message


You are both correct from a simple electrical point of
view it is quite pointless. However, I might point out
that rightly or wrongly, probably a substantial majority
of people with an interest in Hi-Fi would say that
Bi-amped systems sound better

But this isn't really bi-amping. There are still passive
crossovers, and both amplifiers have to amplify the full
signal.

Its not "active" certainly but it is what most would mean
by bi-amped.

Who is this "most"?

Most audio fanatics?

Bi-amped has traditionally meant, and means in most audio circles to this
day, active crossover, two power amps, two-way speaker system.

That a few naive audiophiles have been snookered into buying two amps to a
job that one amp can do as well, is an aberration.


Arny, as this is a UK news group, we normally use UK nomenclature. This side
of the pond, using two amplifiers but retaining the passive crossover is
generally called "bi-amping" whilst using two amplifiers with electronic
crossovers is generally called "active". The former is of no value whilst
the latter provides many benefits.

S.

--
http://audiopages.googlepages.com

"Bob Latham" wrote in message
...
In article ,
Serge Auckland wrote:

Arny, as this is a UK news group, we normally use UK nomenclature. This
side of the pond, using two amplifiers but retaining the passive
crossover is generally called "bi-amping" whilst using two amplifiers
with electronic crossovers is generally called "active".

Sounds about right to me.

The former is of no value whilst the latter provides many benefits.

Such overwhelming confidence presumably means you've tried it.


Bob.

--
Bob Latham
Stourbridge, West Midlands

As I grew up in Broadcast, active 'speakers were quite common. I discovered
active 'speakers for home use in the mid '80s and have not had passive
'speakers since. In my view there are several benefits from active
operation:-

1) Not having a passive crossover means no resistive losses in the
inevitable series resistance of inductors in series with bass units, and
with consequently better damping factor, although it is a moot point as to
how much the slightly improved damping factor matters.

2) Crossover frequencies and slopes can be much more accurately and
repeatedly tailored with electronic crossovers, especially if done in DSP
than is possible with passive lumped components.

3) The power output of an active system is additive, as the bass amplifiers
only amplify bass signals, ditto for the treble. Using two 100 watt
amplifiers driving 8 ohm bass and treble units is equivalent to a single 400
watt amplifier driving the same drive units passively crossovered as the *
peak voltages* are additive.

4) As I don't get pleasure from owning lots of boxes, nor playing mix 'n
match with amps etc, an active system having everything in the one box is
domestically more acceptable, and is cheaper as you're not paying for fancy
boxes for the amps, nor have to find the space for them.


I use Meridian 'speakers in my main system and small Genelecs in my second
system, and nothing I've heard recently would make me change.

S.



--
http://audiopages.googlepages.com

In article , Bob Latham
wrote:
In article , Eiron
wrote:
Dave xxxx wrote:
On another forum a chap says, he has been told, its ok to use a Quad
power amp (140 watts) with a Quad 405 (100 watts) with the same pre
amplifier.


The idea being the 606 powers the bass and the 405 the tweeters.

Speakers being used Spendor s5e

Will this work ?

Quite pointless, as Serge said.

You are both correct from a simple electrical point of view it is quite
pointless. However, I might point out that rightly or wrongly, probably
a substantial majority of people with an interest in Hi-Fi would say
that Bi-amped systems sound better

Where have you seen any figures to support the assertion that the
"majority" would say this? And would it mean more than, "The magazines keep
saying it does"? :-)


and indeed to be "pointless" the amplifiers would have to suffer zero
load issues.

I know, you think the majority are fools - fair enough.

I can't speak for either Dave or Eiron. However I don't think those who
have the above belief are "fools".

Firstly, there are circumstances where bi-amping can change the results for
simple engineering reasons. This thread threw up an example. The amps have
different gains, thus - unless corrected - altering the frequency response
of the system. The result being an expensive and inflexible 'tone control'.

Secondly, people can easily believe all kinds of things if they base their
ideas on what magazines tell them, and/or 'listening tests' that aren't
carried out in a way that might lead to a reliable result. Trivially easy
to mislead youself. No need to be a "fool". Just someone who accepts what
magazines ("experts") say and don't have any idea how many ways there are
for a listening test to give a misleading or worthless result.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html

"Jim Lesurf" wrote in message

In article , Bob
Latham wrote:
In article , Eiron
wrote:
Dave xxxx wrote:
On another forum a chap says, he has been told, its ok
to use a Quad power amp (140 watts) with a Quad 405
(100 watts) with the same pre amplifier.


The idea being the 606 powers the bass and the 405 the
tweeters.

Speakers being used Spendor s5e

Will this work ?

Quite pointless, as Serge said.

You are both correct from a simple electrical point of
view it is quite pointless. However, I might point out
that rightly or wrongly, probably a substantial majority
of people with an interest in Hi-Fi would say that
Bi-amped systems sound better

If bi-amped means active crossover, multiple amplifiers, multiple drivers,
then yes. That's a working technology that is widely used. It is widely used
in pro audio. It's even used in boom-boxes.

Where have you seen any figures to support the assertion
that the "majority" would say this? And would it mean
more than, "The magazines keep saying it does"? :-)

I'd like to see a reference to an article in an audio ragazine with
meaninful circultation about an actual high end product that bi-amps without
an active product. For example, has Stereophile or HFN ever reviewed a
biamped speaker with no active crossover?

and indeed to be "pointless" the amplifiers would have
to suffer zero load issues.

I know, you think the majority are fools - fair enough.

Not so much fools as poorly informed.

I can't speak for either Dave or Eiron. However I don't
think those who have the above belief are "fools".

Ironically, there's an argument that says that putting a normal woofer in
parallel with a highly reactive tweeter through a passive crossover makes
the reactive tweeter an easier load to drive. The signal through the woofer
drives the power amp output stage up its load line where the out-of-phase
current for the tweeters is coming from output transistors that are already
partially saturated from driving the woofer. The voltage across the output
transistors and the power dissipation in the output stage is therefore
reduced.

Firstly, there are circumstances where bi-amping can
change the results for simple engineering reasons. This
thread threw up an example. The amps have different
gains, thus - unless corrected - altering the frequency
response of the system. The result being an expensive and
inflexible 'tone control'.

Agreed. Anyboydy who assigns the 405 to the woofer and the 606 to the
tweeter gets to enjoy brighter treble and a little uptick in the midrange.
"Brighter is better", anyone? ;-)

It's just an expensive, non-adjustable equalizer.

Secondly, people can easily believe all kinds of things
if they base their ideas on what magazines tell them,
and/or 'listening tests' that aren't carried out in a way
that might lead to a reliable result.

In this case, an audible difference is likely. And, if the listener doesn't
agree with Spendor's speaker voicing, then they will perceive an
improvement.

Trivially easy to
mislead youself. No need to be a "fool". Just someone who
accepts what magazines ("experts") say and don't have any
idea how many ways there are for a listening test to give
a misleading or worthless result.

Interesting how many people pooh-pooh equalizers, but rush to accept an
badly-designed "Bi-amp" equalizer implmented by what might be the most
expensive and non-adjustable means possible.

In article , Arny
Krueger
wrote:
"Jim Lesurf" wrote in message

In article , Bob Latham
wrote:

[snip]

Where have you seen any figures to support the assertion that the
"majority" would say this? And would it mean more than, "The magazines
keep saying it does"? :-)

I'd like to see a reference to an article in an audio ragazine with
meaninful circultation about an actual high end product that bi-amps
without an active product. For example, has Stereophile or HFN ever
reviewed a biamped speaker with no active crossover?

I have a vague feeling that HFN may have once reviewed the 'systems' that
some people put together. In general, of course, that won't be anything
that was intended by either the speaker manufacturer or the amp
manufacturer.

However IIRC back in the 1980's there was a UK fad for using multiple Naim
power amps to 'bi amp' the Linn Isobarik. Not sure if Naim or Linn pushed
the idea, but some dealers and 'subjective reviewers' did at the time.

Personally, I disliked both the Isobarik, and the Naim amps. So for me the
main benefit was that it piled the items I didn't want somewhere away from
where I had to encounter them. :-)

FWIW The Isobarik had an impedance that went south at LF, and the Naim
amps of the period had an output 0.22 Ohm series resistor and limited
current capability. So the Naim/Isobarik system did have a different
response to using an amp with low output impedance and decent current
capability. However I tended to make the choice here that wasn't the one
touted in magazines at the time. :-)

At the time Linn dealers used to insist that 'stereo image' was a myth.
Perhaps because you couldn't get one when using Isobariks. ;-

The most dramatic change I ever heard was in a shop when the removed the
Isobariks and tried Quad 63's. From awful to excellent. They shop droids
hated the Quads. But then they were unable to hear that one of the tweeters
in one of the Isobariks was busted... :-)

[snip]

Ironically, there's an argument that says that putting a normal woofer
in parallel with a highly reactive tweeter through a passive crossover
makes the reactive tweeter an easier load to drive. The signal through
the woofer drives the power amp output stage up its load line where the
out-of-phase current for the tweeters is coming from output transistors
that are already partially saturated from driving the woofer. The
voltage across the output transistors and the power dissipation in the
output stage is therefore reduced.

A few months ago there was someone putting a flawed argument forwards on
the 'audioholics' website in a thread about bi-wiring.

The wording of the claims 'evolved' as it was challenged. However it tended
to be based on saying there was a form of 'intermodulation' occurring in
conventional wiring that biwiring removed.

Mysterious consequences were described such as components in the spectrum
that an FFT could not show. Doubters were treated as being unable to grasp
the reality as they lacked the scientific insight of the idea's presenter.
;-

The argument used was incorrect, or at least inappropriate, and thus lead
to an wrong conclusion. I did an analysis and it was another example of how
a simple misconception can mislead, but a detailed analysis takes ages to
show what a good engineer would have thought in the first place. i.e. No
such problem, so no need for biwiring as a 'solution'. No real problem
with the FFT, either. Nor indeed with mudane ideas like linear
superposition, etc. :-)

Shame if anyone though they were hearing what was claimed since the claimed
theory didn't stand up to either measurement or careful analysis based on
the physics involved according to the claimant's own descriptions.

None of which stopped the claimant from continuing to push his idea.

I wonder if any of that appeared in any USA printed mags?... Didn't appear
here in print so far as I know.

[snip]

Interesting how many people pooh-pooh equalizers, but rush to accept an
badly-designed "Bi-amp" equalizer implmented by what might be the most
expensive and non-adjustable means possible.

IIRC the use of biamping, biwiring, etc, all tended to only come into vogue
*after* the gurus decided that 'tone controls are baaaad' and makers saved
cash by stopped including them. No problem for them if the result was that
people bought more amplifiers. :-)

Personally I still like tone controls and balance controls to be avilable.
Although I appreciate them being designed to work well, and to be bypassed
if preferred. Much cheaper and more flexible than biamping IMHO.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html