Another sub-bass option
 

(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.

Another sub-bass option
 

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.

Another sub-bass option
 

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.

Another sub-bass option
 

"Stewart Pinkerton" wrote in message


IOW, check out UK-made Volt drivers,

http://www.voltloudspeakers.co.uk/Lo...tudiorange-opt.
jpg

then stop whining.

Actually, if you compare the technical specs of Volt drivers to the
competitive JL audio drivers, there's plenty for UK buyers to whine about.

Here's a summary from which UK & European sources can be culled.

http://ldsg.snippets.org/sect-12-byEBP.php3#WOOF12-

Just remember, subwoofer performance is dominated by cone diameter and Xmax.

Another sub-bass option
 

"Stewart Pinkerton" wrote in message


IOW, check out UK-made Volt drivers,

http://www.voltloudspeakers.co.uk/Lo...tudiorange-opt.
jpg

then stop whining.

Actually, if you compare the technical specs of Volt drivers to the
competitive JL audio drivers, there's plenty for UK buyers to whine about.

Here's a summary from which UK & European sources can be culled.

http://ldsg.snippets.org/sect-12-byEBP.php3#WOOF12-

Just remember, subwoofer performance is dominated by cone diameter and Xmax.

Another sub-bass option
 

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

Another sub-bass option
 

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

Another sub-bass option
 

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.

Another sub-bass option
 

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.

Another sub-bass option
 

In article , Stewart Pinkerton
wrote:
On Fri, 10 Oct 2003 14:26:48 GMT, "Wally" wrote:


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...........

Are you sure it is the amp clipping as distinct from the speakers reaching
the end of their travel or becoming nonlinear? - i.e. have you measured the
waveforms when this is happening?

I ask because when I was testing amps at high powers many years ago I often
heard 'clipping' at LF, but tests showed that in many cases the amp output
waveform was fine. It was often the speaker that was running into trouble.
In some cases moderate signal nonlinearity was causing the cones to 'creep'
and this reduced the level at which LF would cause the speakers to 'clip'.
A visual sign was the cones seeming to 'suck in' or 'push out' of the
cabinet as this happened. I have never tried the Tannoys you're using,
though, so the speakers I was using may have been rather more limited in
terms of the cone displacements they could handle.

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
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