Connecting subwoofers to a 2-channel audio amp.
 

"Eiron"


I think you will find that they
1) take speaker-level inputs
2) which are directly connected to terminals for the left/right speakers
3) via a resistive network, combine L+R and feed it to an electronic
LP filter and thence to the built-in power amp and subwoofer driver.

Please feel free to give an example of one that works your way.



** Don't ask the STEAMING GREAT IDIOT to do that.

All the useless cretin will do is post links to false and misleading
information.




....... Phil

Connecting subwoofers to a 2-channel audio amp.
 

On Sat, 13 Jan 2007 00:13:08 +0000, Eiron wrote:

Kalman Rubinson wrote:

Posts like this do not deserve any response but, in the small
possibility that someone takes him seriously, I will add that there
are several powered subwoofers which
(1)take speaker-level inputs,
(2)have a passive speaker-level crossover,
(3)feed the high-pass output to terminals for the left/right speakers
and,
(4)via a resistive network, pass the LP output to the built-in power
amp and subwoofer driver.

I think you will find that they
1) take speaker-level inputs
2) which are directly connected to terminals for the left/right speakers
3) via a resistive network, combine L+R and feed it to an electronic
LP filter and thence to the built-in power amp and subwoofer driver.

Please feel free to give an example of one that works your way.

I take your correction for point #3 which is functionally equivalent.
As for point #4, see
http://www.definitivetech.com/specs/...ml#poweredsubs
for an example.

Kal

Connecting subwoofers to a 2-channel audio amp.
 

"Kalman Rubinson Bloody IDIOT "

I take your correction for point #3 which is functionally equivalent.
As for point #4, see
http://www.definitivetech.com/specs/...ml#poweredsubs
for an example.


** An example of what ?

Falsifying specifications ?

Or totally meaningless specifications.





........ Phil

Connecting subwoofers to a 2-channel audio amp.
 

Kalman Rubinson wrote:

On Sat, 13 Jan 2007 00:13:08 +0000, Eiron wrote:


Kalman Rubinson wrote:


Posts like this do not deserve any response but, in the small
possibility that someone takes him seriously, I will add that there
are several powered subwoofers which
(1)take speaker-level inputs,
(2)have a passive speaker-level crossover,
(3)feed the high-pass output to terminals for the left/right speakers
and,
(4)via a resistive network, pass the LP output to the built-in power
amp and subwoofer driver.

I think you will find that they
1) take speaker-level inputs
2) which are directly connected to terminals for the left/right speakers
3) via a resistive network, combine L+R and feed it to an electronic
LP filter and thence to the built-in power amp and subwoofer driver.

Please feel free to give an example of one that works your way.


I take your correction for point #3 which is functionally equivalent.
As for point #4, see
http://www.definitivetech.com/specs/...ml#poweredsubs
for an example.

Thanks for the example. First one I've seen.
That one does feed the speakers via a first order HP crossover,
or in other words, through a capacitor. The turnover frequency varies
according to your speakers, their impedance and Q of any bass resonances
and the tolerance of the capacitor.
A bit of a lottery really.

--
Eiron.

Connecting subwoofers to a 2-channel audio amp.
 

In article , Serge Auckland
wrote:


I really don't understand the point of a variable phase
control. 0 & 180 switched should be provided to phase up the sub with
the mains (which hopefully will be in phase with each other), but apart
from that, I can't see it's possible to match the phase of the main LF,
as it will be frequency dependant. As you suggest, with two subs, trying
to get the phase right would be a nightmare.

I found the variable 'phase' control on the sub I use to be useful. It
allowed me to adjust the response in the region where both the sub and the
main speakers were producing similar output levels. No idea how useful
others would find this, 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

Connecting subwoofers to a 2-channel audio amp.
 

Eiron wrote:


Which model of Harbeth subwoofer do you have?


MS1 (a pair of)

Roy.

Connecting subwoofers to a 2-channel audio amp.
 

"Roy"
Eiron wrote:


Which model of Harbeth subwoofer do you have?


MS1 (a pair of)



** Specifically designed to accompany a particular Harbeth bookshelf
speaker.

Learn to read - ANYTIME - ****WIT.




........ Phil

Connecting subwoofers to a 2-channel audio amp.
 

"Eiron"

Some Kike Idiot posted.

http://www.definitivetech.com/specs/...ml#poweredsubs


Thanks for the example. First one I've seen.


** Chinese sub-woofer " plate amplifiers " are nearly all made like this.

A total scam.



That one does feed the speakers via a first order HP crossover,
or in other words, through a capacitor.


** A very cheap and nasty bi-polar electro of about 250 uF.


The turnover frequency varies
according to your speakers, their impedance and Q of any bass resonances
and the tolerance of the capacitor.


** The x-over frequency is basically non existent with most bookshelf
speakers - whether tuned reflex or sealed.

All bass resonance damping is * completely lost * and little if any of the
desired reduction in cone excursion at sub bass frequencies is supplied by
such a series cap.

A total scam.


A bit of a lottery really.


** Might be OK with a pair of Quad ESL57s.

Nothing else.




....... Phil

Connecting subwoofers to a 2-channel audio amp.
 

Keith G wrote:
"Serge Auckland" wrote in message
...
Keith G wrote:


IOW, is a pair of subs a possible complication that might be best *not*
bothered with....??




Should work wonderfully well using one of your 4W SETs............



Well, on my *8W* SET/InFidelios the results are astounding - 'listening' by
leaning my head back against the (drywall partition) wall, the bass from
Bjork's 'Headphones' without the sub rattles my head anyway. With the sub
though, it is not really bearable for long and quite queasy but there is
some 'wuffa wuffa wuffa' roll-off after a seriously deep bit!

Interestingly, the bass with the sub doesn't actually really sound any
deeper than the speakers on their own, only *feels* it...!!

More, much more, to do yet - mebbe even some recording comparisons....


Seriously, in your room, a single sub should be more than ample.


Sure, I don't think I could stand more than the one!!


As to
phasing, I really don't understand the point of a variable phase control.
0 & 180 switched should be provided to phase up the sub with the mains
(which hopefully will be in phase with each other), but apart from that, I
can't see it's possible to match the phase of the main LF, as it will be
frequency dependant. As you suggest, with two subs, trying to get the
phase right would be a nightmare.


I've twiddled it back and forth and can't say it makes a lot of difference
anyway and it ends up back at 0 deg!


Other controls needed are a crossover frequency selector and a level
control. Ideally, if the main speakers are small (say don't go below 70Hz)
then the extreme bass should be rolled-off to the mains considerably
improving their power handling and lowering distortion.


Not sure I understood that....??


If the main 'speakers are small, they won't reproduce deep bass. Feeding
them with deep bass from the power amp will only serve to stress the
bass unit suspension and heat up the voice coil without actually
producing any sound. It is therefore better to limit the bass drive to
small speakers so that they are only given what they can deal with. It
is actually much better if the bass reduction can be done *before* the
power amplifier so that the PA isn't being asked to generate unusable
volts. This way, the power amp driving the small 'speakers will be able
to generate more volts that the 'speakers *can* handle, and so
effectively produce a higher output.

For my son's Christmas present some years ago, I built him a subwoofer
system consisting of an electronic filter removing bass below a preset
frequency, a mono combiner and filter providing a balanced output to a
single subwoofer. The filter frequencies were selectable as was levels
to the subwoofer. The main 'speakers (small Missions) were connected to
the L&R output of a Quad 303 and were driven from 70Hz upwards. 70Hz
downwards was monoed to a balanced output driving a 100wpc AIWA power
amp in bridge mode into the subwoofer which was a large bass-reflex box
tuned to 20Hz. It was most successful, and saw him through his
University days and afterwards, not always to the pleasure of his
neighbours however....

S.

Connecting subwoofers to a 2-channel audio amp.
 

Phil Allison wrote:
"Roy"
Eiron wrote:

Which model of Harbeth subwoofer do you have?

MS1 (a pair of)



** Specifically designed to accompany a particular Harbeth bookshelf
speaker.

Learn to read - ANYTIME - ****WIT.


But if they work well with others too, then why not?

Halfwit.