On Thu, 09 Oct 2003 14:06:26 GMT, "Wally" wrote:

Stewart Pinkerton wrote:

I'm not whining. I also wasn't looking for new drivers. Arny
suggested the JL ones, but the UK price turned out to be too dear.

You'll find that Volt drivers are also expensive. Good bass drivers
*are* both large and expensive. They're also *necessary*, if you want
clean bass at high levels.

At no point did I say I wanted clean bass at high levels. In an earlier
thread, about bi-amping, I said that I rarely use my 20Wpc amp over half
volume for full program material. I gather an isobaric enclosure needs more
power than one using a single driver, but I don't think my needs would
dictate something in the multiple hundreds of Watts category - maybe
30-40Wpc?

Nope. If you look at the volume of air you need to shift at 20Hz to
obtain even 100dB (not a particularly loud peak level), then you need
a *lot* of power! This is why decent commercial subs invariably have
several hundred watt amps, some go up to a kilowatt!.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:



Nope. If you look at the volume of air you need to shift at 20Hz to
obtain even 100dB (not a particularly loud peak level), then you need
a *lot* of power! This is why decent commercial subs invariably have
several hundred watt amps, some go up to a kilowatt!.


Can I have a little rant?

This thread was about KEF B139s.

If you look at a B139, not with rose-tinted glasses,
but as the woofer in a domestic hi-fi setup, it is excellent.

Maybe it doesn't work as an AV sub to reproduce helicopters
and explosions at window shattering levels but in a reflex box
with -3dB at ~32 Hz or a TL with -10dB at ~20Hz it sounds
pretty damn' good on all of my CDs and vinyl.

What's more, a B139 still works after 30 years, unlike foam-surround
woofers that are dead at 10 years or other newish materials that lose
their shape and fall off (some sort of Goodmans loudspeaker)

So I may buy new speakers, but KEFs will be playing at my funeral. :-)

Thanks,

Roger.

On Thu, 09 Oct 2003 23:59:29 +0100, Old Fart at Play
wrote:

Stewart Pinkerton wrote:

Nope. If you look at the volume of air you need to shift at 20Hz to
obtain even 100dB (not a particularly loud peak level), then you need
a *lot* of power! This is why decent commercial subs invariably have
several hundred watt amps, some go up to a kilowatt!.

Can I have a little rant?

This thread was about KEF B139s.

If you look at a B139, not with rose-tinted glasses,
but as the woofer in a domestic hi-fi setup, it is excellent.

Um, it's a decent woofer, but was overtaken many years ago by more
modern constructions, viz KEFs own 'racetrack' woofers in their
current range.

Maybe it doesn't work as an AV sub to reproduce helicopters
and explosions at window shattering levels but in a reflex box
with -3dB at ~32 Hz or a TL with -10dB at ~20Hz it sounds
pretty damn' good on all of my CDs and vinyl.

Granted, it was never designed for subwoofer duties, and comes from an
era when reproduction below 30Hz was almost an irrelevance, i.e. the
days when vinyl was king.

What's more, a B139 still works after 30 years, unlike foam-surround
woofers that are dead at 10 years or other newish materials that lose
their shape and fall off (some sort of Goodmans loudspeaker)

Well, that's true of any other speaker with a rubber surround. In
fact, over forty years or so of audiophilia, and several dozen pairs
of speakers, I don't think I have ever owned speakers with a foam
surround. The 'other newish materials' you sweepingly denigrate are in
the main responsible for great advances in sound reproduction.
Goodmans haven't made a decent speaker in 30 years, so they are hardly
a good target.

So I may buy new speakers, but KEFs will be playing at my funeral. :-)

Ah now, a *real* audiophile would have gone for Quad '57s! :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

(Stewart Pinkerton) wrote in message ...


So I may buy new speakers, but KEFs will be playing at my funeral. :-)

Ah now, a *real* audiophile would have gone for Quad '57s! :-)

But you can't be buried in an ESL57.

http://www.t-linespeakers.org/classics/coffin

Roger.

(Stewart Pinkerton) wrote in message ...


So I may buy new speakers, but KEFs will be playing at my funeral. :-)

Ah now, a *real* audiophile would have gone for Quad '57s! :-)

But you can't be buried in an ESL57.

http://www.t-linespeakers.org/classics/coffin

Roger.

On Thu, 09 Oct 2003 23:59:29 +0100, Old Fart at Play
wrote:

Stewart Pinkerton wrote:

Nope. If you look at the volume of air you need to shift at 20Hz to
obtain even 100dB (not a particularly loud peak level), then you need
a *lot* of power! This is why decent commercial subs invariably have
several hundred watt amps, some go up to a kilowatt!.

Can I have a little rant?

This thread was about KEF B139s.

If you look at a B139, not with rose-tinted glasses,
but as the woofer in a domestic hi-fi setup, it is excellent.

Um, it's a decent woofer, but was overtaken many years ago by more
modern constructions, viz KEFs own 'racetrack' woofers in their
current range.

Maybe it doesn't work as an AV sub to reproduce helicopters
and explosions at window shattering levels but in a reflex box
with -3dB at ~32 Hz or a TL with -10dB at ~20Hz it sounds
pretty damn' good on all of my CDs and vinyl.

Granted, it was never designed for subwoofer duties, and comes from an
era when reproduction below 30Hz was almost an irrelevance, i.e. the
days when vinyl was king.

What's more, a B139 still works after 30 years, unlike foam-surround
woofers that are dead at 10 years or other newish materials that lose
their shape and fall off (some sort of Goodmans loudspeaker)

Well, that's true of any other speaker with a rubber surround. In
fact, over forty years or so of audiophilia, and several dozen pairs
of speakers, I don't think I have ever owned speakers with a foam
surround. The 'other newish materials' you sweepingly denigrate are in
the main responsible for great advances in sound reproduction.
Goodmans haven't made a decent speaker in 30 years, so they are hardly
a good target.

So I may buy new speakers, but KEFs will be playing at my funeral. :-)

Ah now, a *real* audiophile would have gone for Quad '57s! :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:



Nope. If you look at the volume of air you need to shift at 20Hz to
obtain even 100dB (not a particularly loud peak level), then you need
a *lot* of power! This is why decent commercial subs invariably have
several hundred watt amps, some go up to a kilowatt!.


Can I have a little rant?

This thread was about KEF B139s.

If you look at a B139, not with rose-tinted glasses,
but as the woofer in a domestic hi-fi setup, it is excellent.

Maybe it doesn't work as an AV sub to reproduce helicopters
and explosions at window shattering levels but in a reflex box
with -3dB at ~32 Hz or a TL with -10dB at ~20Hz it sounds
pretty damn' good on all of my CDs and vinyl.

What's more, a B139 still works after 30 years, unlike foam-surround
woofers that are dead at 10 years or other newish materials that lose
their shape and fall off (some sort of Goodmans loudspeaker)

So I may buy new speakers, but KEFs will be playing at my funeral. :-)

Thanks,

Roger.

Stewart Pinkerton wrote:

Nope. If you look at the volume of air you need to shift at 20Hz to
obtain even 100dB (not a particularly loud peak level), then you need
a *lot* of power! This is why decent commercial subs invariably have
several hundred watt amps, some go up to a kilowatt!.

If we assume that the main amp is typically supplying 10Wpc to the mid/top
drivers, what sort of power would be needed from an amp driving a pair of
isobaric bass cabs loaded with B139s? Lets say the bass cabs are sealed
boxes of about 80L each.


--
Wally
www.makearatherlonglinkthattakesyounowhere.com
Things are always clearer in the cold, post-upload light.

On Fri, 10 Oct 2003 14:26:48 GMT, "Wally" wrote:

Stewart Pinkerton wrote:

Nope. If you look at the volume of air you need to shift at 20Hz to
obtain even 100dB (not a particularly loud peak level), then you need
a *lot* of power! This is why decent commercial subs invariably have
several hundred watt amps, some go up to a kilowatt!.

If we assume that the main amp is typically supplying 10Wpc to the mid/top
drivers, what sort of power would be needed from an amp driving a pair of
isobaric bass cabs loaded with B139s? Lets say the bass cabs are sealed
boxes of about 80L each.

You'll be looking at something like 86dB/w/m basic sensitivity from
the B139s (although a fairly tough 4 ohms or less loading), so this
will entirely depend on the sensitivity of your main speakers. Note
also that if you are *typopically * supplying 10 watts to the main
speakers, you'll need at least 50 watts to handle peaks, so you'd have
to be looking at a minimum of 50-100 watt amplifier, with enough
current reserves to handle say a 3 ohm load without buckling. Note
that if you want to keep the bass response flat down to 20-25Hz,
you'll have to use active equalisation, and boost the bass by some
6-10dB. That's *4-10 times* the 'midband' power!

To give you some idea, I use some 11dB of bass equalisation in the
20-30Hz range on a pair of Tannoy 633s that I use for TV sound. These
are 90dB/w/m speakers which take about 3-5 watts of average drive on
action movies with the equaliser out of circuit. When it's in circuit
on a good 'blockbuster' like T2 or U-571, then my Audiolab 8000P,
which puts out a measured 195 watts/channel continuous into 4 ohms,
sometimes clips on the loud stuff...........
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:


that if you want to keep the bass response flat down to 20-25Hz,
you'll have to use active equalisation, and boost the bass by some
6-10dB. That's *4-10 times* the 'midband' power!

To give you some idea, I use some 11dB of bass equalisation in the
20-30Hz range on a pair of Tannoy 633s that I use for TV sound.



Can anyone recommend any music CDs with something in the 20-30Hz range?

Roger.