Using a car amp at home?

[Josh]

I have a good quality car amp which i'd like to use to drive a home
sub. If i was to power it off the 12V rail of a 400W computer PSU
(with a big cap inline) it may run well. But i'm concerned that the
peak current draw will be more than the PSU can cope with.

Another possibility is to suppliment the high volt rails inside the
amp. The amp's DC-DC converter probably bumps the 12V up to +/- 60V. I
have a decent dc rectifier (torroidial, bridge rect, big caps) that
can deliver +/- 70V. Would it work to connect this alternative supply
directly into the amp - thus bypassing its dc-dc stage?

 

[KLR]

On 1 Jun 2004 00:39:13 -0700, josh3010@hotmail.com (Josh) wrote:

I have a good quality car amp which i'd like to use to drive a home
sub. If i was to power it off the 12V rail of a 400W computer PSU
(with a big cap inline) it may run well. But i'm concerned that the
peak current draw will be more than the PSU can cope with.

If you want to learn more about this in detail then you could look up

silicon chip - buy the back issur or get a photocopy made of the
article on this very subject

Im pretty sure that SC did an article in the last year or so on how
to modify the average computer PSU to replace the existing +5/+12
rails with a single +12 rail. (or other more useful voltages It
wasn't a really complex process in theory - more or less remove the
secondary winding of the switching transformer and custom rewind it to
suit your needs. Also the voltage sensing circuitry was modfified to
suit, however I wouldnt recommend doing this mod unless you are
experienced in such things - and mains safety. A lot of the innards
of these power supplies have about 350v dc floating around in them.

Another possibility is to suppliment the high volt rails inside the
amp. The amp's DC-DC converter probably bumps the 12V up to +/- 60V. I
have a decent dc rectifier (torroidial, bridge rect, big caps) that
can deliver +/- 70V. Would it work to connect this alternative supply
directly into the amp - thus bypassing its dc-dc stage?

-----------------------
I think the second option would be the best one, specially if you
already have the surplus parts on hand. I would connect the amp up to
a 12v bench supply (or car battery) and - locate the secondary of the
DC DC converter inside and measure its rails.

A suitable Linear power supply can then be made or adaped to run it
directly. I would isolate the output of the internal DC converter
though. also the internal + - rail capacitors wont be big enough for
50hz based transformer supply - so when you build it - you will need
to add some good sized electrolytics across the rails to provide
adequate filtering.

if the amp is going to be in the order of 400w total then 10,000 UF or
more on each rail would be a good start.

--------------------------

 

[TonyP]

"Josh" <josh3010@hotmail.com> wrote in message
news:6923e56d.0405312339.6f8fd493@posting.google.com...

Another possibility is to suppliment the high volt rails inside the
amp. The amp's DC-DC converter probably bumps the 12V up to +/- 60V. I
have a decent dc rectifier (torroidial, bridge rect, big caps) that
can deliver +/- 70V. Would it work to connect this alternative supply
directly into the amp - thus bypassing its dc-dc stage?

Get real, a "400W" car amp is probably about 40-50W RMS per channel.
So +/- 70V is bound to be too high for the transistors/fets in a car amp.
Easy enough to measure though.

TonyP.

 

[stoj]

I am currently powering a 12in sub form a 222W car amp off a standard
transformer purchased form jaycar (using just a bridge, capacitor and a
fuse) it seems to be working fine. The average current drawn for the amp is
around the 5A to 6A mark. So just test the current drawn and try and find a
transformer to suit the average requirements of the amp. Hope that helps


"TonyP" <TonyP@optus.net.com.au> wrote in message
news:40bef10a$0$8987$afc38c87@news.optusnet.com.au...

"Josh" <josh3010@hotmail.com> wrote in message
news:6923e56d.0405312339.6f8fd493@posting.google.com...
Another possibility is to suppliment the high volt rails inside the
amp. The amp's DC-DC converter probably bumps the 12V up to +/- 60V. I
have a decent dc rectifier (torroidial, bridge rect, big caps) that
can deliver +/- 70V. Would it work to connect this alternative supply
directly into the amp - thus bypassing its dc-dc stage?

Get real, a "400W" car amp is probably about 40-50W RMS per channel.
So +/- 70V is bound to be too high for the transistors/fets in a car amp.
Easy enough to measure though.

TonyP.