New page on Squares waves and amplifier performance
 

On 11/01/2010 20:02, Serge Auckland wrote:

"bcoombes" bcoombes@orangedotnet wrote in message
o.uk...
Serge Auckland wrote:
In the mid 80s, I owned a HiFi shop,

"bcoombes" bcoombes@orangedotnet wrote in message

Where was it and what was it's name..being nosy. :)



--
Bill Coombes

It was Beechwood Audio, opened in 1984 in Braintree Essex, then in 1986 in
Bury St Edmunds. Went bust in 1987 after failing to realise that very few
buyers of HiFi equipment had any engineering appreciation, and would buy
anything that the magazine scribblers recommended. I majored on CD when
every magazine was in the pay of the Flat Earth Society, nor would I have
any truck with stuff that didn't make sense from an engineering
perspective.

Sold a lot of Quad, KEF and Nakamichi, but not enough to make it pay.

Ho Hum....
S.



Lovely bloke Serge and a serious boffin - but never learned 'where tha's
muck, tha's brass'...!!!

(Ask that ****** Alan Sugar - he knows how to make chunky money peddling
turds...)

New page on Squares waves and amplifier performance
 

"Ian Iveson" wrote

Staggered, once again. Next time I see you, you should be in
sackcloth and ashes.

In the meantime I suggest you check out how a cathode
follower works, and in particular how its output impedance
is defined.

You can be as "staggered" as you like, but I assure you I have no intention
of appearing in sackcloth and ashes any time soon. I am perfectly well aware
of how cathode followers work, how the output impedance is defined and the
reasons for cathode follower failure. The output impedance is irrelevant to
CF failure, it is, as I said simply a matter of the time constant of the
load seen at the cathode.

Then look into the meaning of the phrase "slew rate
limiting". I guess Wikipedia would be an appropriate place
to start. You may argue that it has acquired a wider, more
sloppily-defined meaning, but I prefer to keep the useful
distinctions that a disciplined use of language is able to
convey. In any case, no matter how sloppily defined it may
have become, your own interpretation is far beyond the pale.

Well OK, if you wish to keep to your definition of "slew rate limiting".

Engineers weren't daft in the days of valve amps. Had slew rate limiting
been a problem, it would have been recognised.


Who said it's a problem?

David.

New page on Squares waves and amplifier performance
 

"Don Pearce" wrote in message
...
On Mon, 11 Jan 2010 19:51:04 -0000, "David Looser"
wrote:


Indeed, excessive bandwidth of the incoming signal. But as Jim showed a
simple passive filter on the input to the amplifier solves it.

Reducing the bandwidth of the amplifier.

If you regard the filter as part of the amplifier. Since it is outside the
feedback loop I would say it's not. Rather it reduces the bandwidth of the
signal.

David.

New page on Squares waves and amplifier performance
 

On Mon, 11 Jan 2010 20:54:01 -0000, "David Looser"
wrote:

"Don Pearce" wrote in message
...
On Mon, 11 Jan 2010 19:51:04 -0000, "David Looser"
wrote:


Indeed, excessive bandwidth of the incoming signal. But as Jim showed a
simple passive filter on the input to the amplifier solves it.

Reducing the bandwidth of the amplifier.

If you regard the filter as part of the amplifier. Since it is outside the
feedback loop I would say it's not. Rather it reduces the bandwidth of the
signal.

David.


No, it is part of the amplifier - a very necessary part. Otherwise it
would be part of the record deck, the microphone, the CD player etc -
and it would need to be variable to cope with all the different
amplifiers that might be connected.

d

New page on Squares waves and amplifier performance
 

"Don Pearce" wrote

No, it is part of the amplifier - a very necessary part. Otherwise it
would be part of the record deck, the microphone, the CD player etc -

It doesn't have to be part of anything.

and it would need to be variable to cope with all the different
amplifiers that might be connected.

No, because it's only ever used with the the one amplifier. *Physically* it
may be part of the amp, but as it's outside the NFB loop it's not part of
the amp in a functional sense.

David.

New page on Squares waves and amplifier performance
 

David Looser wrote:
"bcoombes" bcoombes@orangedotnet wrote
And I said something about HF roll-off where exactly?

quote
It solved the hiss problem by simply slicing off everything above 8k.
unquote


Slicing off would mean literally 'the total elimination' (above a certain
point). Roll-off doesn't..or it wouldn't be a a roll. I don't intend to take
this any further BTW.

--
Bill Coombes

New page on Squares waves and amplifier performance
 

Keith G wrote:
On 11/01/2010 20:02, Serge Auckland wrote:



Lovely bloke Serge and a serious boffin - but never learned 'where tha's
muck, tha's brass'...!!!

(Ask that ****** Alan Sugar - he knows how to make chunky money peddling
turds...)


Yeah, he's living proof that thoroughly objectionable people often succeed in
the world. (In financial terms anyway) :)
--
Bill Coombes

New page on Squares waves and amplifier performance
 

On Mon, 11 Jan 2010 21:05:21 -0000, "David Looser"
wrote:

"Don Pearce" wrote

No, it is part of the amplifier - a very necessary part. Otherwise it
would be part of the record deck, the microphone, the CD player etc -

It doesn't have to be part of anything.

It is part of the amplifier because it is an integral and necessary
part of the design of the amplifier. It defines a part of the
amplifier's behaviour. It has nothing to do with any other component
of the audio chain.

and it would need to be variable to cope with all the different
amplifiers that might be connected.

No, because it's only ever used with the the one amplifier. *Physically* it
may be part of the amp, but as it's outside the NFB loop it's not part of
the amp in a functional sense.


I don't follow the distinction. What has the NFB loop got to do with
this? What would you do with an amplifier that has no global NFB? Is
it not an amplifier at all as a result?

d

New page on Squares waves and amplifier performance
 

Serge Auckland wrote:

"bcoombes" bcoombes@orangedotnet wrote in message
o.uk...
Serge Auckland wrote:
In the mid 80s, I owned a HiFi shop,

"bcoombes" bcoombes@orangedotnet wrote in message

Where was it and what was it's name..being nosy. :)



--
Bill Coombes

It was Beechwood Audio, opened in 1984 in Braintree Essex, then in 1986 in
Bury St Edmunds. Went bust in 1987 after failing to realise that very few
buyers of HiFi equipment had any engineering appreciation, and would buy
anything that the magazine scribblers recommended.

Yeah, nobody ever went broke underestimating the stupidity of the average
punter...or words to that effect. :)

I majored on CD when every magazine was in the pay of the Flat Earth Society, nor would I have
any truck with stuff that didn't make sense from an engineering perspective.

That'd be most of it then. :(


Sold a lot of Quad, KEF and Nakamichi, but not enough to make it pay.


Shame.


--
Bill Coombes

New page on Squares waves and amplifier performance
 

"bcoombes" bcoombes@orangedotnet wrote in message
o.uk...
David Looser wrote:
"bcoombes" bcoombes@orangedotnet wrote
And I said something about HF roll-off where exactly?

quote
It solved the hiss problem by simply slicing off everything above 8k.
unquote


Slicing off would mean literally 'the total elimination' (above a certain
point).

That's impossible.

Roll-off doesn't..or it wouldn't be a a roll.

Since there is no such thing as "slicing-off" the term "roll-off" is the
most reasonable interpretation of what you said.

I don't intend to take this any further BTW.

No point.

David.