In article , Dave Plowman (News)
wrote:
In article , Eeyore
wrote:



You need to know the R, L and C of cable. It makes a complex filter.

With the output impedance of a decent amp being 2 10ths of FA, the
capacitance of any practical cable doesn't matter.

This assumes the amp is stable into whatever the resulting load may be
presented to its output terminals. Also that loading at ultrasonic
frequencies has no other effect on its performance which may show up in the
audio range. I'd expect that for a decently designed amplifier. But I am
less confident it will apply for every design that people sell. :-)

Nor should the inductance with a properly designed amp.

Erm... the problem with cable impedance is that it is a series
contribution. May not bother the amplifier, but can change the signal
patterns at the load at the other end of the cable. Particularly with
speakers that are essentially capacitive at HF.

Some LS cables have inductances of the order of 1 microH/m or more. FWIW
I've been measuring LS cables recently, and cables with inductances of the
order of 0.5 microH/m seem to be more common than people might expect! :-)

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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Audio Misc http://www.audiomisc.co.uk/index.html

Eeyore wrote:

Does you car stereo sound better when you fill the tank with Shell ?

Actually... yes.

No, seriously. Bear with me.

When I fill up at Shell with V-Power diesel the engine runs smoother and
quieter than it does with supermarket special diesel.

Which means I don't get that raspy sound coming up over the music when I
accelerate (usually sideways) off a a roundabout.

And no, it's not snake oil... it's diesel oil. :-P

--
Squirrel Solutions Ltd Tel: (01453) 845735
http://www.squirrelsolutions.co.uk/ Fax: (01453) 843773

Registered in England: 05877408

In article ,
Eeyore wrote:
Does anyone make a high quality single channel active speaker?

God Yes !

Ans were I not so astonished you asked I'd answer right now !

I know of several single unit powered speakers - but I'd not describe them
as high quality. They're simply convenient for stand alone use in a pro
environment.

--
*42.7% of statistics are made up. Sorry, that should read 47.2% *

Dave Plowman London SW
To e-mail, change noise into sound.

Glenn Richards wrote:

Eeyore wrote:

Does you car stereo sound better when you fill the tank with Shell ?

Actually... yes.

No, seriously. Bear with me.

When I fill up at Shell with V-Power diesel the engine runs smoother and
quieter than it does with supermarket special diesel.

Which means I don't get that raspy sound coming up over the music when I
accelerate (usually sideways) off a a roundabout.

And no, it's not snake oil... it's diesel oil. :-P

Well fancy that ! Who'd have guessed it ?

You ought to write in to the car audio ragazines.

Graham

"Dave Plowman (News)" wrote:

Eeyore wrote:
Does anyone make a high quality single channel active speaker?

God Yes !

Ans were I not so astonished you asked I'd answer right now !

I know of several single unit powered speakers - but I'd not describe them
as high quality. They're simply convenient for stand alone use in a pro
environment.

What level are you thinking at ?

KRKs seem to be very well though of at present. I think they do powered
versions.

Graham

"Dave Plowman (News)" wrote:

Eeyore wrote:
Does anyone make a high quality single channel active speaker?

God Yes !

Ans were I not so astonished you asked I'd answer right now !

I know of several single unit powered speakers - but I'd not describe them
as high quality. They're simply convenient for stand alone use in a pro
environment.

Oh and Genelec are still around.
http://www.genelec.com/

and here's the KRK site.
http://www.krksys.com/

PMCs are LOVELY. Not sure if they do powered models.
http://www.pmc-speakers.com/

Graham

On 2008-07-14, Jim Lesurf wrote:
In article , Dave Plowman (News)
wrote:
In article , Eeyore
wrote:
You need to know the R, L and C of cable. It makes a complex filter.

With the output impedance of a decent amp being 2 10ths of FA, the
capacitance of any practical cable doesn't matter.

This assumes the amp is stable into whatever the resulting load may be
presented to its output terminals. Also that loading at ultrasonic
frequencies has no other effect on its performance which may show up in the
audio range. I'd expect that for a decently designed amplifier. But I am
less confident it will apply for every design that people sell. :-)

Nor should the inductance with a properly designed amp.

Erm... the problem with cable impedance is that it is a series
contribution. May not bother the amplifier, but can change the signal
patterns at the load at the other end of the cable. Particularly with
speakers that are essentially capacitive at HF.

Some LS cables have inductances of the order of 1 microH/m or more. FWIW
I've been measuring LS cables recently, and cables with inductances of the
order of 0.5 microH/m seem to be more common than people might expect! :-)

From some of my amp-cable-speaker modelling (using GNUCAP):

Belden 9718 12 AWG:
R = 10.8 mOhms/metre; C = 72.2 pF/metre; L = 755 nH/metre

Maplin's "Shark 12 Gauge" (it's actually much beefier than 12 AWG):
R = 4.8 mOhms/metre; C = 59.6 pF/metre; L = 660 nH/metre

The Belden is from manufacturer specs (I think). The "Shark" is
calculated by me from the actual cable's geometry.

Both of these show a *small* high treble droop across the load, with
5 metres connected to a complex load modelled on my own rather benign
'speakers. It's a fairly broad band droop so it's just concievable it
might be audible to a good, young set of ears (but not mine, I think).

Paralleled cat 5 has much lower inductance (at the expense of a lot more
capacitance) and is very good in the high treble.

(At least as far as GNUCAP calculates - the real world is often
different.)

--
John Phillips

John Phillips wrote:
On 2008-07-14, Jim Lesurf wrote:
In article , Dave Plowman (News)
wrote:
In article , Eeyore
wrote:
You need to know the R, L and C of cable. It makes a complex filter.
With the output impedance of a decent amp being 2 10ths of FA, the
capacitance of any practical cable doesn't matter.
This assumes the amp is stable into whatever the resulting load may be
presented to its output terminals. Also that loading at ultrasonic
frequencies has no other effect on its performance which may show up in the
audio range. I'd expect that for a decently designed amplifier. But I am
less confident it will apply for every design that people sell. :-)

Nor should the inductance with a properly designed amp.
Erm... the problem with cable impedance is that it is a series
contribution. May not bother the amplifier, but can change the signal
patterns at the load at the other end of the cable. Particularly with
speakers that are essentially capacitive at HF.

Some LS cables have inductances of the order of 1 microH/m or more. FWIW
I've been measuring LS cables recently, and cables with inductances of the
order of 0.5 microH/m seem to be more common than people might expect! :-)

From some of my amp-cable-speaker modelling (using GNUCAP):

Belden 9718 12 AWG:
R = 10.8 mOhms/metre; C = 72.2 pF/metre; L = 755 nH/metre

Maplin's "Shark 12 Gauge" (it's actually much beefier than 12 AWG):
R = 4.8 mOhms/metre; C = 59.6 pF/metre; L = 660 nH/metre

The Belden is from manufacturer specs (I think). The "Shark" is
calculated by me from the actual cable's geometry.

Both of these show a *small* high treble droop across the load, with
5 metres connected to a complex load modelled on my own rather benign
'speakers. It's a fairly broad band droop so it's just concievable it
might be audible to a good, young set of ears (but not mine, I think).

Paralleled cat 5 has much lower inductance (at the expense of a lot more
capacitance) and is very good in the high treble.

(At least as far as GNUCAP calculates - the real world is often
different.)


As ever with cables, what determines the response is the square root of
the ratio of the inductance to the capacitance. It matter nothing what
each is individually.

The closer you can get that figure to 8, the flatter the speaker
response will be.

d

Don Pearce wrote:

As ever with cables, what determines the response is the square root of
the ratio of the inductance to the capacitance. It matter nothing what
each is individually.

The closer you can get that figure to 8, the flatter the speaker
response will be.

So figure-8 cable is the best sort. :-)

--
Eiron.

Eiron wrote:
Don Pearce wrote:

As ever with cables, what determines the response is the square root
of the ratio of the inductance to the capacitance. It matter nothing
what each is individually.

The closer you can get that figure to 8, the flatter the speaker
response will be.

So figure-8 cable is the best sort. :-)


Ta-Daaa!

d