In the "Amp swap disappointment" thread, below, Ian has said that it's
possible to accurately measure the differences between each amp and, I would
assume, judge just what it is about one amp that might make it preferable to
another amp, to some listeners.

Would it therefore be possible for someone to take a "straight-line" amp -
and I'm happy to accept whatever you judge to be a representation of the
closest example of this - and then build an add on "filter" to alter its
sound to reproduce the sound quality of the Alchemist?

Then, maybe, a dozen or so other popular amps could be measured, and filters
built to represent each amp in turn.

Would I be able to hear the difference between the "straight-line" amp with
the Alchemist filter and the Alchemist amp?

JustMe wrote:
In the "Amp swap disappointment" thread, below, Ian has said that it's
possible to accurately measure the differences between each amp and, I would
assume, judge just what it is about one amp that might make it preferable to
another amp, to some listeners.

Would it therefore be possible for someone to take a "straight-line" amp -
and I'm happy to accept whatever you judge to be a representation of the
closest example of this - and then build an add on "filter" to alter its
sound to reproduce the sound quality of the Alchemist?

Then, maybe, a dozen or so other popular amps could be measured, and filters
built to represent each amp in turn.

Would I be able to hear the difference between the "straight-line" amp with
the Alchemist filter and the Alchemist amp?



This is the guitar amp version of what you are talking about

http://www.kellyindustries.com/guitars/line_6_pod.html

--
Nick

"JustMe" wrote in message
...
In the "Amp swap disappointment" thread, below, Ian has said that it's
possible to accurately measure the differences between each amp and, I
would
assume, judge just what it is about one amp that might make it preferable
to
another amp, to some listeners.

**A reasonable assumption. Of course, the measurements need to be VERY
comprehensive. Far more comprehensive than those supplied by almost every
amplifier manufacturer.


Would it therefore be possible for someone to take a "straight-line" amp -
and I'm happy to accept whatever you judge to be a representation of the
closest example of this - and then build an add on "filter" to alter its
sound to reproduce the sound quality of the Alchemist?

**Maybe. Maybe your Alchemist already IS a straight line amplifier. If it
has problems, it would be possible to duplicate those problems - at a cost,
of course.


Then, maybe, a dozen or so other popular amps could be measured, and
filters
built to represent each amp in turn.

**Yes. It would be difficult, but doable.


Would I be able to hear the difference between the "straight-line" amp
with
the Alchemist filter and the Alchemist amp?

**Not if it has been done right.


--
Trevor Wilson
www.rageaudio.com.au

JustMe wrote:

In the "Amp swap disappointment" thread, below, Ian has said that it's
possible to accurately measure the differences between each amp and, I would
assume, judge just what it is about one amp that might make it preferable to
another amp, to some listeners.

Correct.

Would it therefore be possible for someone to take a "straight-line" amp -
and I'm happy to accept whatever you judge to be a representation of the
closest example of this - and then build an add on "filter" to alter its
sound to reproduce the sound quality of the Alchemist?

yes.

Then, maybe, a dozen or so other popular amps could be measured, and filters
built to represent each amp in turn.

You could do this.

Would I be able to hear the difference between the "straight-line" amp with
the Alchemist filter and the Alchemist amp?

Assuming the alchemist distorts in some way (you say that it makes an
audible difference elsewhere, so I assume it does), yes.

In article , JustMe
wrote:
In the "Amp swap disappointment" thread, below, Ian has said that it's
possible to accurately measure the differences between each amp and, I
would assume, judge just what it is about one amp that might make it
preferable to another amp, to some listeners.

Would it therefore be possible for someone to take a "straight-line" amp
- and I'm happy to accept whatever you judge to be a representation of
the closest example of this - and then build an add on "filter" to alter
its sound to reproduce the sound quality of the Alchemist?

In principle, yes, although the definition of what is required would
probably have to be broader than a 'filter'. In practice, difficult, as a
number of properties may be involved. Some may not be correctly identified,
and others may depend upon the conditions of use.

Then, maybe, a dozen or so other popular amps could be measured, and
filters built to represent each amp in turn.

Would I be able to hear the difference between the "straight-line" amp
with the Alchemist filter and the Alchemist amp?

Can't say as it would presumably depend upon how well the "filter" actually
represents the totality of the processes the Alchemist is performing.

What you *could* do, though is something like the following.

Play music through the Alchemist into a pair of speakers. While doing so,
connect leads to the speaker terminals and record the signals there onto
CD-R using a reasonably quality recorder. Note the signal level with a
meter.

The replay the recorded version of the signals using a different amp that
is known to have a flat response, low distortion, and low output impedance,
adjusing the level at the speakers to be as before. Then judge how similar
it sounds.

Repeat this process, but reversing the positions of the amps. Or using one
of them 'twice'. Compare, contrast, discuss. :-)

Alternatively, it would be possible in principle to do a 'live' version of
the above and avoid recording, although this would be more complex to set
up. Might make it easier to do a 'blind' check, though...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Ian Molton" wrote in message
...
JustMe wrote:

In the "Amp swap disappointment" thread, below, Ian has said that it's
possible to accurately measure the differences between each amp and, I
would
assume, judge just what it is about one amp that might make it
preferable to
another amp, to some listeners.

Correct.

Would it therefore be possible for someone to take a "straight-line"
amp -
and I'm happy to accept whatever you judge to be a representation of the
closest example of this - and then build an add on "filter" to alter its
sound to reproduce the sound quality of the Alchemist?

yes.

Then, maybe, a dozen or so other popular amps could be measured, and
filters
built to represent each amp in turn.

You could do this.

Would I be able to hear the difference between the "straight-line" amp
with
the Alchemist filter and the Alchemist amp?

Assuming the alchemist distorts in some way (you say that it makes an
audible difference elsewhere, so I assume it does), yes.

I find this very interesting!

The consensus is that this is perfectly possible.

So, someone could build an amp which mimics the qualities of other amps,
simply by accurately measuring various aspects of the amps to be mimicked
and applying filters appropriately.

Could these filters be placed onto an IC and switched on the front panel?

That way, I can have my "straight-wire" amp and switch between "Alchemist
APD6a" mode, "Keith's Chinese valve amp" mode, "Audiolab 8000LX" mode,
"Cyrus V" mode, etc.

Nick points to a box which seems to not only reproduce the qualities of
amps, but speakers too.

How can this be? Surely a speaker's performance is influenced heavily by the
amp's ability to drive it well and by the acoustics of the environment in
which it is placed?

JustMe wrote:

I find this very interesting!

The consensus is that this is perfectly possible.

No reason why not really.

Could these filters be placed onto an IC and switched on the front panel?

I'd be inclined to use a decent DSP and allow it to be programmed from a
PC personally...

That way, I can have my "straight-wire" amp and switch between "Alchemist
APD6a" mode, "Keith's Chinese valve amp" mode, "Audiolab 8000LX" mode,
"Cyrus V" mode, etc.

Yup.

Nick points to a box which seems to not only reproduce the qualities of
amps, but speakers too.

How can this be?

I dont see how it can be since to do so the box would need to have
knowledge of (at least) your room acoustics and speaker properties, and
(preferably) the room characteristics the 'target' speaker is used in.

(on top of that you'd need a profile for the other speaker, of course.)

In the "Amp swap disappointment" thread, below, Ian has said that it's
possible to accurately measure the differences between each amp and, I
would assume, judge just what it is about one amp that might make it
preferable to another amp, to some listeners.

Would it therefore be possible for someone to take a "straight-line" amp
- and I'm happy to accept whatever you judge to be a representation of
the closest example of this - and then build an add on "filter" to alter
its sound to reproduce the sound quality of the Alchemist?

In principle, yes, although the definition of what is required would
probably have to be broader than a 'filter'. In practice, difficult, as a
number of properties may be involved. Some may not be correctly
identified,
and others may depend upon the conditions of use.

Accepted. I use the term "filter" for simplicity but, I'd imagine that you'd
have to measure more than just the amp's frequency response. It would have
to be a "filter" constructed on the amp's performance at a given time - say
when the amp was perceived to be operating at its best.

Then, maybe, a dozen or so other popular amps could be measured, and
filters built to represent each amp in turn.

Would I be able to hear the difference between the "straight-line" amp
with the Alchemist filter and the Alchemist amp?

Can't say as it would presumably depend upon how well the "filter"
actually
represents the totality of the processes the Alchemist is performing.

What you *could* do, though is something like the following.

Play music through the Alchemist into a pair of speakers. While doing so,
connect leads to the speaker terminals and record the signals there onto
CD-R using a reasonably quality recorder. Note the signal level with a
meter.

The replay the recorded version of the signals using a different amp that
is known to have a flat response, low distortion, and low output
impedance,
adjusing the level at the speakers to be as before. Then judge how similar
it sounds.

Repeat this process, but reversing the positions of the amps. Or using one
of them 'twice'. Compare, contrast, discuss. :-)

Alternatively, it would be possible in principle to do a 'live' version of
the above and avoid recording, although this would be more complex to set
up. Might make it easier to do a 'blind' check, though...

I would be happy to try something like this blind. I'd be really curious to
see if such "filters" were possible and whether I would be able to tell
differences, or recognise my favourites as superior to those which I'd
previously rejected.

Presumably the playback equipment would have to be that which is considered
as "straight-line" - the CD player and amp? But is there a danger of a
cumulative effect? If I use the same speakers in replaying the signal as
it's been recorded from the system, would the effects of the speaker's
balance not be duplicated? Would this be cumulative? Presumably, any small
deviance from "straight-line" in the CD or amp's replay would undermine such
an experiment.

Many of you chaps believe that the Peter Walker(?) "straight-wire" ideal is
that which any "hifi" designer should aspire to construct.

Do you think that this is attainable?

Slainte,

Jim

Cheers!

"JustMe" wrote in message


So, someone could build an amp which mimics the qualities of other
amps, simply by accurately measuring various aspects of the amps to
be mimicked and applying filters appropriately.

More specifically and technically, the adjustment facility for amplifier
mimicry would be a combination of linear and non-linear compensators.

A regular audio equalizer (parametric preferred, graphic accepted) would be
a kind of linear compensator.

There are no common high fidelity audio components that are intended to be
nonlinear compensators. The *Pod* device someone else mentioned may be an
example of such a device. However, its generally pretty sonically deadly to
put a complete musical signal through a highly nonlinear device because of
all of the non-harmonic spurious responses. When nonlinear devices are used,
they are usually used with just one voice or just one instrument.

If I was going to try to make a chameleon amplifier, I would start out with
a good clean pro audio type amp ( Hafler, Crown, QSC). I would front end it
with a 5-band parametric eq per channel. I might add a back-end device that
would provide a variable, perhaps even frequency-dependent source impedance
for the loudspeaker.

In use, I would try to duplicate the speaker voice-coil voltage of the amp
being *duplicated* by intelligent adjustment of the source impedance
simulator, and then fine tune the results with the parametric eq(s).

Wise audiophiles wishing to get off the new amplifier merry-go-round would
cut to the chase and just get some parametric eqs for their own system. Then
(and here is the hard part) they would learn to adjust them properly by ear.

So, someone could build an amp which mimics the qualities of other
amps, simply by accurately measuring various aspects of the amps to
be mimicked and applying filters appropriately.

More specifically and technically, the adjustment facility for amplifier
mimicry would be a combination of linear and non-linear compensators.

A regular audio equalizer (parametric preferred, graphic accepted) would
be
a kind of linear compensator.

There are no common high fidelity audio components that are intended to be
nonlinear compensators. The *Pod* device someone else mentioned may be an
example of such a device. However, its generally pretty sonically deadly
to
put a complete musical signal through a highly nonlinear device because of
all of the non-harmonic spurious responses. When nonlinear devices are
used,
they are usually used with just one voice or just one instrument.

If I was going to try to make a chameleon amplifier, I would start out
with
a good clean pro audio type amp ( Hafler, Crown, QSC). I would front end
it
with a 5-band parametric eq per channel. I might add a back-end device
that
would provide a variable, perhaps even frequency-dependent source
impedance
for the loudspeaker.

In use, I would try to duplicate the speaker voice-coil voltage of the amp
being *duplicated* by intelligent adjustment of the source impedance
simulator, and then fine tune the results with the parametric eq(s).

Wise audiophiles wishing to get off the new amplifier merry-go-round would
cut to the chase and just get some parametric eqs for their own system.
Then
(and here is the hard part) they would learn to adjust them properly by
ear.

This probably comes down to semantics: do you view an audiophile as someone
who specifically seeks "straight-wire" sound, or is an audiophile anyone who
is critical of, seeks out and appreciates what they perceive to be superior
sound?

If the former then wouldn't they be better off purchasing the
"straight-wire" source, amp and speakers, and not playing with eqs to
compensate for the inferiority of "curly-wire" products?

If the latter then how can you quantify what is a "proper" adjustment of an
eq, beyond whatever the listener prefers?