Don Pearce wrote:



In another area of amplifier design, damping factors vary enormously from one model to another and yet rates no mention in advertising at all.

I am speaking of guitar amps, where the effective DF may be anything from 100 to 0.1 or lower - making for very audible differences.

Famous valve amps like Marshall and Fender have DFs of about 1 due to use of modest amounts of NFB. Early VOX amplifiers were class A and used no NFB at all resulting if very low DF numbers like 0.1. When VOX released their first SS models, the DF was even lower than the valve ones - due to using a combination of voltage and current feedback.

The same idea is still used in lot of modern SS guitar amps to get DFs of between 0.3 and 2, so mimicking the tonal character of popular valve models.

But makers keep it all a big secret.

How very odd.



Guitar amplifiers are a case apart.


** Sure - where wildly varying damping factors actually have a big effect on sound and makers studiously avoid any mention of it.

While the complete opposite occurs with hi-fi amps.



.... Phil

On Sat, 13 Dec 2014 15:27:20 -0800 (PST), Phil Allison
wrote:

Don Pearce wrote:



In another area of amplifier design, damping factors vary enormously from one model to another and yet rates no mention in advertising at all.

I am speaking of guitar amps, where the effective DF may be anything from 100 to 0.1 or lower - making for very audible differences.

Famous valve amps like Marshall and Fender have DFs of about 1 due to use of modest amounts of NFB. Early VOX amplifiers were class A and used no NFB at all resulting if very low DF numbers like 0.1. When VOX released their first SS models, the DF was even lower than the valve ones - due to using a combination of voltage and current feedback.

The same idea is still used in lot of modern SS guitar amps to get DFs of between 0.3 and 2, so mimicking the tonal character of popular valve models.

But makers keep it all a big secret.

How very odd.



Guitar amplifiers are a case apart.


** Sure - where wildly varying damping factors actually have a big effect on sound and makers studiously avoid any mention of it.

They don't studiously avoid mention of it. The high output impedance
is an integral part of the design philosophy. They design to ensure
that there is a low enough damping factor to allow the speaker cone to
sing properly. And getting the figure right is part of their
intellectual property, not a bragging item.

d

Don Pearce wrote:


Guitar amplifiers are a case apart.


** Sure - where wildly varying damping factors actually have a big effect on sound and makers studiously avoid any mention of it.

They don't studiously avoid mention of it.


** Yes they do - you bull****ting old fool.


The high output impedance
is an integral part of the design philosophy.

** Except for all the ones that have low and medium output impedance.


They design to ensure
that there is a low enough damping factor to allow the speaker cone to
sing properly.

** That is utter ********.

And getting the figure right is part of their
intellectual property, not a bragging item.


** Completely insane crap.

Most would say that Don has lost it - but I know he never had a single clue in the first place.




..... Phil

On Sun, 14 Dec 2014 00:31:17 -0800 (PST), Phil Allison
wrote:

Don Pearce wrote:


Guitar amplifiers are a case apart.


** Sure - where wildly varying damping factors actually have a big effect on sound and makers studiously avoid any mention of it.

They don't studiously avoid mention of it.


** Yes they do - you bull****ting old fool.


The high output impedance
is an integral part of the design philosophy.

** Except for all the ones that have low and medium output impedance.


They design to ensure
that there is a low enough damping factor to allow the speaker cone to
sing properly.

** That is utter ********.

And getting the figure right is part of their
intellectual property, not a bragging item.


** Completely insane crap.

Most would say that Don has lost it - but I know he never had a single clue in the first place.




.... Phil



And normal service has resumed.

d