Trevor Wilson wrote:


Can anyone define 'Slam' in the context of audio power amps?


**Tell you what to do:

1) Find a nice pair of difficult to drive, full range loudspeakers. A pair
of AR9s, some old Infinity's (Kappa 9, RS1.5, RS2.5, etc), Linn Isobarics,
Duntech Sovereigns, Crown Princes, B&W 801, 802 (et al), KEF 105, 104 (et
al). would all be suitable candidates.
2) Now find two, similarly powered amplifiers. One, a decently designed BJT
amp, with a flat frequency response and adequate current delivery for the
above-mentioned speakers. Rotel, Krell, Arcam all make suitable products.
Now find a low bias MOSFET amp. Perreaux and several other manufacturers
make suitable products.
3) Listen to some music which has fast, dynamic, percussive sounds.

After this, you will probably understand what I mean by the term: 'slam'.


Now I understand!

Slam is an amplifier/speaker combination working as designed,
without being overdriven.

Perhaps you could define a lack of slam.

Roger.

"Old Fart at Play" wrote in message
...
Trevor Wilson wrote:


Can anyone define 'Slam' in the context of audio power amps?


**Tell you what to do:

1) Find a nice pair of difficult to drive, full range loudspeakers. A
pair
of AR9s, some old Infinity's (Kappa 9, RS1.5, RS2.5, etc), Linn
Isobarics,
Duntech Sovereigns, Crown Princes, B&W 801, 802 (et al), KEF 105, 104
(et
al). would all be suitable candidates.
2) Now find two, similarly powered amplifiers. One, a decently designed
BJT
amp, with a flat frequency response and adequate current delivery for
the
above-mentioned speakers. Rotel, Krell, Arcam all make suitable
products.
Now find a low bias MOSFET amp. Perreaux and several other manufacturers
make suitable products.
3) Listen to some music which has fast, dynamic, percussive sounds.

After this, you will probably understand what I mean by the term:
'slam'.


Now I understand!

Slam is an amplifier/speaker combination working as designed,
without being overdriven.

**Nope. At no time should the amplifiers be allowed to exceed their maximum
Voltage/current limits. I thought that was a given, in any proper test. I
specified the above equipment, because it should expose the effect readily.
With other brands/models, the effect may be noticable, but (possibly) less
obvious.


Perhaps you could define a lack of slam.

**Perhaps you could assemble the equipment I mentioned and see for yourself.
Most of it is old and reasonably common.


--
Trevor Wilson
www.rageaudio.com.au

In article , Trevor Wilson
wrote:
[snip]

Now I understand!

Slam is an amplifier/speaker combination working as designed, without
being overdriven.

**Nope. At no time should the amplifiers be allowed to exceed their
maximum Voltage/current limits. I thought that was a given, in any
proper test. I specified the above equipment, because it should expose
the effect readily. With other brands/models, the effect may be
noticable, but (possibly) less obvious.

In that case I am afraid that I am personally unclear what you mean, since
when in the past I have compared BJT and MOSFET amps then - provided they
have the same frequency response and output impedance and are not clipping
or being overdriven - then I have no recollection of hearing any difference
which I might think could be called 'slam'.

i *have* heard mosfet (and other amps) in the past that changed the sound
when driving difficult loads as a result of limiting or high output
impedance. But if I understanding you correctly, you are excluding this
mechanism from what you say.

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

In article , Trevor Wilson
wrote:
[snip]

Now I understand!

Slam is an amplifier/speaker combination working as designed, without
being overdriven.

**Nope. At no time should the amplifiers be allowed to exceed their
maximum Voltage/current limits. I thought that was a given, in any
proper test. I specified the above equipment, because it should expose
the effect readily. With other brands/models, the effect may be
noticable, but (possibly) less obvious.

In that case I am afraid that I am personally unclear what you mean, since
when in the past I have compared BJT and MOSFET amps then - provided they
have the same frequency response and output impedance and are not clipping
or being overdriven - then I have no recollection of hearing any difference
which I might think could be called 'slam'.

i *have* heard mosfet (and other amps) in the past that changed the sound
when driving difficult loads as a result of limiting or high output
impedance. But if I understanding you correctly, you are excluding this
mechanism from what you say.

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

"Old Fart at Play" wrote in message
...
Trevor Wilson wrote:


Can anyone define 'Slam' in the context of audio power amps?


**Tell you what to do:

1) Find a nice pair of difficult to drive, full range loudspeakers. A
pair
of AR9s, some old Infinity's (Kappa 9, RS1.5, RS2.5, etc), Linn
Isobarics,
Duntech Sovereigns, Crown Princes, B&W 801, 802 (et al), KEF 105, 104
(et
al). would all be suitable candidates.
2) Now find two, similarly powered amplifiers. One, a decently designed
BJT
amp, with a flat frequency response and adequate current delivery for
the
above-mentioned speakers. Rotel, Krell, Arcam all make suitable
products.
Now find a low bias MOSFET amp. Perreaux and several other manufacturers
make suitable products.
3) Listen to some music which has fast, dynamic, percussive sounds.

After this, you will probably understand what I mean by the term:
'slam'.


Now I understand!

Slam is an amplifier/speaker combination working as designed,
without being overdriven.

**Nope. At no time should the amplifiers be allowed to exceed their maximum
Voltage/current limits. I thought that was a given, in any proper test. I
specified the above equipment, because it should expose the effect readily.
With other brands/models, the effect may be noticable, but (possibly) less
obvious.


Perhaps you could define a lack of slam.

**Perhaps you could assemble the equipment I mentioned and see for yourself.
Most of it is old and reasonably common.


--
Trevor Wilson
www.rageaudio.com.au