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.

"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.

This story comes around every once in a while - different details, same
basic old wife's tale.

Speakers being used Spendor s5e

Will this work ?

Yes, but without some engineering, it is pretty pointless.

Said Quad told him they have the same "gain"

Not true.

http://www.hifiengine.com/download_c...p?quad_606.pdf says the
606 puts out 140 watts with 0.5 volt input.

http://www.hifiengine.com/download_c...5_brochure.pdf
says the 405 puts out 100 watts with 0.5 volt input.

http://stereophile.com/floorloudspea...or/index4.html

Shows a fairly typical impedance curve. Note that the impedance of this
speaker in the tweeter's range is 10 ohms, which means that it is
providing only a small fraction of the total load on the power amp that is
driving it.

"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.

"Dave xxxx"

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.

Said Quad told him they have the same "gain"



** Quad is a company, not a person.

What some staffer allegedly said on the phone to some fool who was incapable
of comprehending his own question, let alone the reply he got, is purest
******** !!


The 405 and the 606 have the same nominal " input sensitivity" of 500mV.

But NOT the same gain !!

The 606 has just on 2 dB more gain.



........ Phil

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

"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.

"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.

"MiNe 109" wrote in message


In article ,

"Arny Krueger" wrote:

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

Hence the term 'passive bi-amping' to distinguish it from
your definition.

There's a whole forest of made-up terms out there for this sort of
weirdness:

vertical bi-amp

horizontal bi-amp

come to mind.

A possible case for the passive method is as an
intermediate step for one who wishes to complete the
active system later.

Almost everything is possible in the world of imagination. Doesn't make many
of them anything like a good idea.

OTOH, traditional biamping is becoming a trend, as a delivered complete
engineered speaker/amp system, not a random collection of parts thrown
together by clueless audiophile dupes and shyster sales hacks.