how can I tell if either of my amps are bridgeable, I want to run a
subwoofer in mono and I have no manuals for either...

sherwood AX4103
denon PMA-720

Theo wrote:
how can I tell if either of my amps are bridgeable, I want to run a
subwoofer in mono and I have no manuals for either...

sherwood AX4103
denon PMA-720

and also does anyone know where I can find somewhere to buy a mono power amp
IC kit, I have looked in maplins but they only went up to 40w, my sub has
two 12" 350w drivers and a low pass filter..

"Theo" theo*+*@*+*letsblowitup*.*com wrote in message
.uk...
how can I tell if either of my amps are bridgeable, I want to run a
subwoofer in mono and I have no manuals for either...

sherwood AX4103
denon PMA-720

**All amplifiers (save a minute number) are bridgeable. What dictates the
success of such an operation are the following:

* The MINIMUM impedance of the speaker.
* The MINIMUM impedance that the amplifier is rated to drive.

Divide the minimum impedance of the speaker (not the average impedance,
which is the usually supplied figure) by 2. If that figure is lower than the
minimum impedance rating of your amplifier, then you can't do it.

Some general rules of thumb (or is that thumbs).

* Unless the manufacturer provides specific switching, or bridging adaptors,
they should not be bridged.
* Very few Denon amps can be successfully bridged into less than 8 Ohm
loads.
* Since Sherwood amps are generally crap, they cannot be bridged into ANY
speaker.


--
Trevor Wilson
www.rageaudio.com.au

Trevor Wilson wrote:
"Theo" theo*+*@*+*letsblowitup*.*com wrote in message
.uk...
how can I tell if either of my amps are bridgeable, I want to run a
subwoofer in mono and I have no manuals for either...

sherwood AX4103
denon PMA-720

**All amplifiers (save a minute number) are bridgeable. What dictates
the success of such an operation are the following:

* The MINIMUM impedance of the speaker.
* The MINIMUM impedance that the amplifier is rated to drive.

Divide the minimum impedance of the speaker (not the average
impedance, which is the usually supplied figure) by 2. If that figure
is lower than the minimum impedance rating of your amplifier, then
you can't do it.
Some general rules of thumb (or is that thumbs).

* Unless the manufacturer provides specific switching, or bridging
adaptors, they should not be bridged.
* Very few Denon amps can be successfully bridged into less than 8 Ohm
loads.
* Since Sherwood amps are generally crap, they cannot be bridged into
ANY speaker.

whats the best option for driving my sub then? new amp or is there another
way?

Theo wrote:

Trevor Wilson wrote:

"Theo" theo*+*@*+*letsblowitup*.*com wrote in message
. co.uk...

how can I tell if either of my amps are bridgeable, I want to run a
subwoofer in mono and I have no manuals for either...

sherwood AX4103
denon PMA-720

**All amplifiers (save a minute number) are bridgeable. What dictates
the success of such an operation are the following:

* The MINIMUM impedance of the speaker.
* The MINIMUM impedance that the amplifier is rated to drive.

Divide the minimum impedance of the speaker (not the average
impedance, which is the usually supplied figure) by 2. If that figure
is lower than the minimum impedance rating of your amplifier, then
you can't do it.
Some general rules of thumb (or is that thumbs).

* Unless the manufacturer provides specific switching, or bridging
adaptors, they should not be bridged.
* Very few Denon amps can be successfully bridged into less than 8 Ohm
loads.
* Since Sherwood amps are generally crap, they cannot be bridged into
ANY speaker.


whats the best option for driving my sub then? new amp or is there another
way?

Just use one channel of the power amp.

Eiron wrote:
Theo wrote:

Trevor Wilson wrote:

"Theo" theo*+*@*+*letsblowitup*.*com wrote in message
.uk...

how can I tell if either of my amps are bridgeable, I want to run a
subwoofer in mono and I have no manuals for either...

sherwood AX4103
denon PMA-720

**All amplifiers (save a minute number) are bridgeable. What
dictates the success of such an operation are the following:

* The MINIMUM impedance of the speaker.
* The MINIMUM impedance that the amplifier is rated to drive.

Divide the minimum impedance of the speaker (not the average
impedance, which is the usually supplied figure) by 2. If that
figure is lower than the minimum impedance rating of your
amplifier, then you can't do it.
Some general rules of thumb (or is that thumbs).

* Unless the manufacturer provides specific switching, or bridging
adaptors, they should not be bridged.
* Very few Denon amps can be successfully bridged into less than 8
Ohm loads.
* Since Sherwood amps are generally crap, they cannot be bridged
into ANY speaker.


whats the best option for driving my sub then? new amp or is there
another way?

Just use one channel of the power amp.

one side of it? is that safe

On Sat, 27 Nov 2004 12:03:09 +0000, Theo wrote:

Theo wrote:
how can I tell if either of my amps are bridgeable, I want to run a
subwoofer in mono and I have no manuals for either...

sherwood AX4103
denon PMA-720

and also does anyone know where I can find somewhere to buy a mono power
amp IC kit, I have looked in maplins but they only went up to 40w, my sub
has two 12" 350w drivers and a low pass filter..

How about one of these modules?
http://www.bkelec.com/DIY.htm
I have one of their old bipolar transistor ones here that my brother built
into a sub. It's been running on and off (depending on who could find room
for it at the time...) for years! £43-85 incl vat for 100w with a
built in power supply can't be bad.

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk

"mick" wrote
How about one of these modules?
http://www.bkelec.com/DIY.htm
I have one of their old bipolar transistor ones here that my brother built
into a sub. It's been running on and off (depending on who could find room
for it at the time...) for years! £43-85 incl vat for 100w with a
built in power supply can't be bad.

Bloody hell, those modules have been around for YEARS, haven't they?!

Specs look a bit... well, for example, the 100W nominal one claims
105W into 8 Ohms (fair enough), but only 115W into 4 Ohms. Krell it
ain't.

Worse yet, the amp marketed as 1000W is positively cheeky:

8 Ohms: 550W -- HUH? I thought this was meant to be 1000W Cheeky gits.
4 Ohms: 725W
2 Ohms: 1050W

Even quartering the load resistance, you get less than a doubling of
supplied power.

Still, they're cheap so you can't really complain, but I think that given that
their 100W amp really does deliver 105W into 8 Ohms, it's a ****ing cheek
that you only get 550W from the "1000W" amp, and you need to go down to 2 Ohms
to get your 1000W!



Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.fleetie.demon.co.uk

Fleetie wrote:
"mick" wrote
How about one of these modules?
http://www.bkelec.com/DIY.htm
I have one of their old bipolar transistor ones here that my brother
built into a sub. It's been running on and off (depending on who
could find room for it at the time...) for years! £43-85 incl vat
for 100w with a built in power supply can't be bad.

Bloody hell, those modules have been around for YEARS, haven't they?!

Specs look a bit... well, for example, the 100W nominal one claims
105W into 8 Ohms (fair enough), but only 115W into 4 Ohms. Krell it
ain't.

Worse yet, the amp marketed as 1000W is positively cheeky:

8 Ohms: 550W -- HUH? I thought this was meant to be 1000W Cheeky
gits. 4 Ohms: 725W
2 Ohms: 1050W

Even quartering the load resistance, you get less than a doubling of
supplied power.

Still, they're cheap so you can't really complain, but I think that
given that their 100W amp really does deliver 105W into 8 Ohms, it's
a ****ing cheek that you only get 550W from the "1000W" amp, and you
need to go down to 2 Ohms to get your 1000W!



Martin

any other idea's then martin? i want a mono setup ideally.

any other idea's then martin? i want a mono setup ideally.

I'm sure they'll be fine for your application. I mean how many watts
do you really need?!


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.fleetie.demon.co.uk