more from the 'The Old Fogey school' of uk.rec.audio-ism:

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

Roger.


Prob not what you were asking but I came accross SLAM as "Symmetrically
Loaded Acoustic Modules", thanks to the guys marketing cheap(ish) computer
speakers - the sort with 4 little satelites and a 6 inch sub driver.

--
Jim H jh
@333
.org

"The Old Fogey" wrote in message
om...
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'.



--
Trevor Wilson
www.rageaudio.com.au

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

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.

"The Old Fogey" wrote in message
om...
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'.



--
Trevor Wilson
www.rageaudio.com.au

"The Old Fogey" wrote in message
om...
Can anyone define 'Slam' in the context of audio power amps?

The ability to deal with sudden short lived transient sounds - preferably
without affecting the rest of the output of the amp. Normally acheived with
good PSU design and big power reserves and capable of transient output well
beyond the units continuous ratings.