Andre Jute wrote:
Time to return to tech-talk.

In a modest-sized room (by horn standards anyway) I want to rig up a
singleton of my modded semi-Fidelio bicor horns for Lowther PM6A. I
thought I'd do the monoing in a specially made 1 metre cable between
the CD player and the power amp.

The QUAD CD expects to see at least 10K impedance on its outputs.
Output of the CD player is 2Vrms and about 0.5Vrms of that is required
to drive the amp to enough power to handle the horns, so high value
resistors can be used in the monomaker if there is any advantage to be
gained.

However, the sound is NOT intended to be reprocessed as stereo
downstream (home installation, not studio); if I want stereo again,
i'll just plug in a stereo cable.

The pot on the integrated amp is probably (the board won't be here
until Tuesday and i can't read the spec on the piccie) 50K Alps but I
can replace it with a DACT of which I have a good selection of values.

So what value resistors would you use for monoing?

How many? Only two, or three?

With your choice of values, what can I expect to lose from the monoing
in bandwidth as distinct from gain?

Andre Jute
Visit Jute on Amps at
http://www.audio-talk.co.uk/fiultra/
"wonderfully well written and reasoned information for the tube audio
constructor"
John Broskie TubeCAD& GlassWare
"an unbelievably comprehensive web site containing vital gems of
wisdom"
Stuart Perry Hi-Fi News& Record Review
#

I would use 3 resistors, all 10K. I think you can guess how to wire them. The important thing is to
place them at the amp end.

Cheers

Ian

On 06/09/2010 20:48, Ian Bell wrote:
Andre Jute wrote:
Time to return to tech-talk.

In a modest-sized room (by horn standards anyway) I want to rig up a
singleton of my modded semi-Fidelio bicor horns for Lowther PM6A. I
thought I'd do the monoing in a specially made 1 metre cable between
the CD player and the power amp.

The QUAD CD expects to see at least 10K impedance on its outputs.
Output of the CD player is 2Vrms and about 0.5Vrms of that is required
to drive the amp to enough power to handle the horns, so high value
resistors can be used in the monomaker if there is any advantage to be
gained.

However, the sound is NOT intended to be reprocessed as stereo
downstream (home installation, not studio); if I want stereo again,
i'll just plug in a stereo cable.

The pot on the integrated amp is probably (the board won't be here
until Tuesday and i can't read the spec on the piccie) 50K Alps but I
can replace it with a DACT of which I have a good selection of values.

So what value resistors would you use for monoing?

How many? Only two, or three?

With your choice of values, what can I expect to lose from the monoing
in bandwidth as distinct from gain?

Andre Jute
Visit Jute on Amps at
http://www.audio-talk.co.uk/fiultra/
"wonderfully well written and reasoned information for the tube audio
constructor"
John Broskie TubeCAD& GlassWare
"an unbelievably comprehensive web site containing vital gems of
wisdom"
Stuart Perry Hi-Fi News& Record Review
#

I would use 3 resistors, all 10K. I think you can guess how to wire
them. The important thing is to place them at the amp end.

Can't guess how to wire them to give the desired attenuation.

--
Eiron.

On Sep 6, 3:26*pm, "Arny Krueger" wrote:
"Eeyore" m
wrote in . com

Andre Jute wrote:
The QUAD CD expects to see at least 10K impedance on its
outputs.
I suspect you are misreading the spec. I expect that is
the 'nominal' load but I'd be VERY surprised if it can't
drive a lower impedance. Without schematics to hand I
couldn't give a precise figure.

For openers, the title "QUAD CD" *does not describe a single piece of
equipment, or even a single family of related products. There are at two
families of Quad CD players, *the 67 family and the 99 family. * The Quad 99
series players further compound the situation by having two different sets
of outputs with very difference performance specs.

I suspect that Jute is basing his alleged specification on the standard IHFM
line level load which includes a 10K resistive component. If that's the case
then he's still in error because the proper way to address that load is with
a device that expects to see 10K or *less*.

You're a blustering idiot, Krueger. This is from the QUAD official
literature of the CD66 and it states "10K minimum*: " Audio Output:
2Vrms maximum. 300mV on normal progamme material. Minimum load
impedance 10kR."

What part of "minimum load impedance 10KR" do you fail to understand,
Krueger?

We have three idiots pontificating about a simple number, which all
three have got it wrong -- but not one of them has bothered to look it
up! But meaningwhile these three morons are smacking their chops in
glee that someone else got it "wrong." How childish. No wonder these
newsgroups remain in intensive care.

Andre Jute
"The brain of an engineer is a delicate instrument which must be
protected against the unevenness of the ground." -- Wifredo-Pelayo
Ricart Medina

On Sep 6, 3:10*pm, John Byrns wrote:
In article
,
*Andre Jute wrote:





Time to return to tech-talk.

In a modest-sized room (by horn standards anyway) I want to rig up a
singleton of my modded semi-Fidelio bicor horns for Lowther PM6A. I
thought I'd do the monoing in a specially made 1 metre cable between
the CD player and the power amp.

The QUAD CD expects to see at least 10K impedance on its outputs.
Output of the CD player is 2Vrms and about 0.5Vrms of that is required
to drive the amp to enough power to handle the horns, so high value
resistors can be used in the monomaker if there is any advantage to be
gained.

However, the sound is NOT intended to be reprocessed as stereo
downstream (home installation, not studio); if I want stereo again,
i'll just plug in a stereo cable.

The pot on the integrated amp is probably (the board won't be here
until Tuesday and i can't read the spec on the piccie) 50K Alps but I
can replace it with a DACT of which I have a good selection of values.

So what value resistors would you use for monoing?

How many? Only two, or three?

With your choice of values, what can I expect to lose from the monoing
in bandwidth as distinct from gain?

Hi Andre,

I would use two 12k resistors, connecting one to each of the two outputs
of the CD player, with the other ends of the two resistors tied together
to feed mono amp. *I would place the resistors at the output end of the
cable to minimize phase shifts at the higher frequencies due to the
effects of cable capacitance, that is use a stereo cable right up to the
input of the mono amp where the mixing network is. *The loss with this
arrangement will be minimal, with a mono signal of 2Vrms from each
channel of the CD player, you will see 1.79Vrms across a 50k amplifier
input resistance.

--
Regards,

John Byrns

Surf my web pages at, *http://fmamradios.com/

Thanks, John. I have a couple of 15K resistors in my junkbox, so I
think I'll use them, at the power amp end of the cable -- good tip
that. I don't see that it matters if the output impedance is 7K5 as
there is no cable-length to drive. More on the amp when the
installation is finished.

Thanks to all who contributed.

Andre Jute
Visit Jute on Amps at
http://www.audio-talk.co.uk/fiultra/
"wonderfully well written and reasoned information for the tube audio
constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site containing vital gems of
wisdom"
Stuart Perry Hi-Fi News & Record Review

"Andre Jute" wrote in message

On Sep 6, 3:26 pm, "Arny Krueger"
wrote:
"Eeyore"
m
wrote in
. com

Andre Jute wrote:
The QUAD CD expects to see at least 10K impedance on
its outputs.
I suspect you are misreading the spec. I expect that is
the 'nominal' load but I'd be VERY surprised if it can't
drive a lower impedance. Without schematics to hand I
couldn't give a precise figure.

For openers, the title "QUAD CD" does not describe a
single piece of equipment, or even a single family of
related products. There are at two families of Quad CD
players, the 67 family and the 99 family. The Quad 99
series players further compound the situation by having
two different sets of outputs with very difference
performance specs.

I suspect that Jute is basing his alleged specification
on the standard IHFM line level load which includes a
10K resistive component. If that's the case then he's
still in error because the proper way to address that
load is with a device that expects to see 10K or *less*.

You're a blustering idiot, Krueger.

Jute, it is true that getting sucked into responding to one of your posts
takes a certain amount of either optimism (that you would have finally grown
a brain) or idiocy (expecting you to change your behavior).

This is from the QUAD
official literature of the CD66 and it states "10K
minimum*: " Audio Output: 2Vrms maximum. 300mV on normal
progamme material. Minimum load impedance 10kR."

Jute, I see that you've already assigned fault to me for not being able to
read your mind and somehow know which Quad CD player you were whining about.

Far be it from you to take responsibility for making a unnecessarily vague
post.

In article ,
Ian Bell wrote:

Andre Jute wrote:
Time to return to tech-talk.

In a modest-sized room (by horn standards anyway) I want to rig up a
singleton of my modded semi-Fidelio bicor horns for Lowther PM6A. I
thought I'd do the monoing in a specially made 1 metre cable between
the CD player and the power amp.

The QUAD CD expects to see at least 10K impedance on its outputs.
Output of the CD player is 2Vrms and about 0.5Vrms of that is required
to drive the amp to enough power to handle the horns, so high value
resistors can be used in the monomaker if there is any advantage to be
gained.

However, the sound is NOT intended to be reprocessed as stereo
downstream (home installation, not studio); if I want stereo again,
i'll just plug in a stereo cable.

The pot on the integrated amp is probably (the board won't be here
until Tuesday and i can't read the spec on the piccie) 50K Alps but I
can replace it with a DACT of which I have a good selection of values.

So what value resistors would you use for monoing?

How many? Only two, or three?

With your choice of values, what can I expect to lose from the monoing
in bandwidth as distinct from gain?

Andre Jute
Visit Jute on Amps at
http://www.audio-talk.co.uk/fiultra/
"wonderfully well written and reasoned information for the tube audio
constructor"
John Broskie TubeCAD& GlassWare
"an unbelievably comprehensive web site containing vital gems of
wisdom"
Stuart Perry Hi-Fi News& Record Review
#

I would use 3 resistors, all 10K. I think you can guess how to wire them. The
important thing is to
place them at the amp end.

There is only one logical way to connect the first two resistors, and
then seemingly only one place to connect the odd resistor, but what is
the point of including the third 10k resistor?

--
Regards,

John Byrns

Surf my web pages at, http://fmamradios.com/

In message , John Byrns
writes
In article ,
Ian Bell wrote:

Andre Jute wrote:
Time to return to tech-talk.

In a modest-sized room (by horn standards anyway) I want to rig up a
singleton of my modded semi-Fidelio bicor horns for Lowther PM6A. I
thought I'd do the monoing in a specially made 1 metre cable between
the CD player and the power amp.

The QUAD CD expects to see at least 10K impedance on its outputs.
Output of the CD player is 2Vrms and about 0.5Vrms of that is required
to drive the amp to enough power to handle the horns, so high value
resistors can be used in the monomaker if there is any advantage to be
gained.

However, the sound is NOT intended to be reprocessed as stereo
downstream (home installation, not studio); if I want stereo again,
i'll just plug in a stereo cable.

The pot on the integrated amp is probably (the board won't be here
until Tuesday and i can't read the spec on the piccie) 50K Alps but I
can replace it with a DACT of which I have a good selection of values.

So what value resistors would you use for monoing?

How many? Only two, or three?

With your choice of values, what can I expect to lose from the monoing
in bandwidth as distinct from gain?

Andre Jute
Visit Jute on Amps at
http://www.audio-talk.co.uk/fiultra/
"wonderfully well written and reasoned information for the tube audio
constructor"
John Broskie TubeCAD& GlassWare
"an unbelievably comprehensive web site containing vital gems of
wisdom"
Stuart Perry Hi-Fi News& Record Review
#

I would use 3 resistors, all 10K. I think you can guess how to wire
them. The
important thing is to
place them at the amp end.

There is only one logical way to connect the first two resistors, and
then seemingly only one place to connect the odd resistor, but what is
the point of including the third 10k resistor?

One assumes that the output impedance of the CD player is low compared
with the 10k input impedance of the amplifier (100 ohms to 1k?).

Provided 'relatively low' is not 'really low', you'll probably get away
with simply paralleling the two outputs. However, just in case, you need
the two resistors to prevent one output more-or-less shorting out the
other (and vice versa). Something like a couple of 5 to 10k resistors
(preferably at the amplifier end) should work just fine, at the expense
of a little audio level.

There is absolutely no virtue in having a third resistor. It will serve
no purpose, and only lower the audio level further.
--
Ian

On 07/09/2010 17:19, Ian Jackson wrote:
In message , John Byrns
writes
In article ,
Ian Bell wrote:

Andre Jute wrote:
Time to return to tech-talk.

In a modest-sized room (by horn standards anyway) I want to rig up a
singleton of my modded semi-Fidelio bicor horns for Lowther PM6A. I
thought I'd do the monoing in a specially made 1 metre cable between
the CD player and the power amp.

The QUAD CD expects to see at least 10K impedance on its outputs.
Output of the CD player is 2Vrms and about 0.5Vrms of that is required
to drive the amp to enough power to handle the horns, so high value
resistors can be used in the monomaker if there is any advantage to be
gained.

However, the sound is NOT intended to be reprocessed as stereo
downstream (home installation, not studio); if I want stereo again,
i'll just plug in a stereo cable.

The pot on the integrated amp is probably (the board won't be here
until Tuesday and i can't read the spec on the piccie) 50K Alps but I
can replace it with a DACT of which I have a good selection of values.

So what value resistors would you use for monoing?

How many? Only two, or three?

With your choice of values, what can I expect to lose from the monoing
in bandwidth as distinct from gain?

Andre Jute
Visit Jute on Amps at
http://www.audio-talk.co.uk/fiultra/
"wonderfully well written and reasoned information for the tube audio
constructor"
John Broskie TubeCAD& GlassWare
"an unbelievably comprehensive web site containing vital gems of
wisdom"
Stuart Perry Hi-Fi News& Record Review
#

I would use 3 resistors, all 10K. I think you can guess how to wire
them. The
important thing is to
place them at the amp end.

There is only one logical way to connect the first two resistors, and
then seemingly only one place to connect the odd resistor, but what is
the point of including the third 10k resistor?

One assumes that the output impedance of the CD player is low compared
with the 10k input impedance of the amplifier (100 ohms to 1k?).

Provided 'relatively low' is not 'really low', you'll probably get away
with simply paralleling the two outputs. However, just in case, you need
the two resistors to prevent one output more-or-less shorting out the
other (and vice versa). Something like a couple of 5 to 10k resistors
(preferably at the amplifier end) should work just fine, at the expense
of a little audio level.

There is absolutely no virtue in having a third resistor. It will serve
no purpose, and only lower the audio level further.

You didn't read the original question very carefully, did you?
It's always a good idea to attenuate a CD output so that you can
turn the volume up to 11 without clipping or overdriving the speakers.
Because there may be teenagers in the house when you're out....

--
Eiron.

"Andre Jute" wrote in message

Time to return to tech-talk.

In a modest-sized room (by horn standards anyway) I want
to rig up a singleton of my modded semi-Fidelio bicor
horns for Lowther PM6A. I thought I'd do the monoing in a
specially made 1 metre cable between the CD player and
the power amp.

The QUAD CD expects to see at least 10K impedance on its
outputs.

So what value resistors would you use for monoing?

I would use 2 10K resistors, one in series with each source.

On 7/09/2010 12:34 p.m., Andre Jute wrote:
On Sep 6, 3:26 pm, "Arny wrote:
"Eeyore"rabbitsfriendsandrelati...@removethishotm ail.com
wrote in . com

Andre Jute wrote:
The QUAD CD expects to see at least 10K impedance on its
outputs.
I suspect you are misreading the spec. I expect that is
the 'nominal' load but I'd be VERY surprised if it can't
drive a lower impedance. Without schematics to hand I
couldn't give a precise figure.

For openers, the title "QUAD CD" does not describe a single piece of
equipment, or even a single family of related products. There are at two
families of Quad CD players, the 67 family and the 99 family. The Quad 99
series players further compound the situation by having two different sets
of outputs with very difference performance specs.

I suspect that Jute is basing his alleged specification on the standard IHFM
line level load which includes a 10K resistive component. If that's the case
then he's still in error because the proper way to address that load is with
a device that expects to see 10K or *less*.

You're a blustering idiot, Krueger. This is from the QUAD official
literature of the CD66 and it states "10K minimum*: " Audio Output:
2Vrms maximum. 300mV on normal progamme material. Minimum load
impedance 10kR."

What part of "minimum load impedance 10KR" do you fail to understand,
Krueger?

We have three idiots pontificating about a simple number, which all
three have got it wrong -- but not one of them has bothered to look it
up! But meaningwhile these three morons are smacking their chops in
glee that someone else got it "wrong." How childish. No wonder these
newsgroups remain in intensive care.

Andre Jute
"The brain of an engineer is a delicate instrument which must be
protected against the unevenness of the ground." -- Wifredo-Pelayo
Ricart Medina

I am surprised that someone who purports to design & build amplifiers etc.
would have to ask such a basic question. This is electronics 101.......
However in the interests of being helpful, read this link and learn a
little http://www.rane.com/note109.html