RE: Whole House Audio

["Keith Doxey" <ukha@xxxxxxx>]

Therefore it follows that they probably cost more than a reasonable quality
Domestic HiFi amp which would be eminently more suited to Whole House
Audio.

Running a Car Amp via a mains powered supply is grossly inefficient anyway.
The amp itself will not run on 12V internally otherwise to realise an
output
of 150W the load would have to be less than about 0.5ohms.

Typically a 150W amp requires a 50-0-50 power supply, or to put in another
way +50V, 0V, -50V. That means the amp has an internal switch mode power
supply to increase the voltage.

For a mains powered 150W amplifier, a 50-0-50 supply only needs 4 parts.

1	Heavy Toroidal Transformer 35-0-35 @ > 150VA
2	Bridge Rectifier 35A @ 150 PIV
3 & 4 Electrolytic Capacitors >10000uF @ 63V

Simple, Reliable, Loads of oomph in reserve.

I have a homebuilt amp rated at 4x150W into 4 ohms or 4x112W into 8 ohms.
The Power supply is a 500VA transformer with 22000uF capacitors.

At normal domestic listening levels you can unplug it from the mains and
plug it into another socket without losing sound as long as you take less
than 15 seconds. I like a good power supply. If its over engineered it
lasts
forever :-))

Keith

> -----Original Message-----
> From: Phil Harris [mailto:phillip.harris1@xxxxxxx]
> Sent: 20 June 2001 20:06
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] Whole House Audio
>
>
>
> Genesis are not mass market amps ... their ratings are very
conservative -
> much like Mission or Naim but in the car audio world. I'd happily pit
a
> Genesis in car amp against most of the semi-decent home amps on the
market
> and they'd do well.
>
> Unfortunately running an amp from 12v is pretty inefficient ... I used
to
> have an Orion 2100HCCA that we tested once at 1,280w RMS bridged
> into a 2ohm
> load without clipping and at that it was drawing slightly less
> that 220Amps
> at 13.8v.
>
> Phil
>
> > -----Original Message-----
> > From: Keith Doxey [mailto:ukha@xxxxxxx]
> > Sent: 20 June 2001 19:21
> > To: ukha_d@xxxxxxx
> > Subject: RE: [ukha_d] Whole House Audio
> >
> >
> > Where does the other 150W go?
> >
> > 50% efficiency is absolutely terrible !
> >
> > Be aware that car amplifiers seldom quote the RMS rating and they
> > never qute
> > the distortion figures at the output they claim. The true power
> > rating at an
> > acceptable distortion level is often very low.
> >
> > Keith
> >
> > > -----Original Message-----
> > > From: James Hoye [mailto:james.hoye@xxxxxxx]
> > > Sent: 20 June 2001 16:51
> > > To: ukha_d@xxxxxxx
> > > Subject: RE: [ukha_d] Whole House Audio
> > >
> > >
> > > This email was delivered to you by The Free Internet,
> > > a Business Online Group company. http://www.thefreeinternet.net
> > >
---------------------------------------------------------------
> > > > If it's just background type music and not ear
splitting
> > volumes that's
> > > > needed then you can get in-car amplifiers quite
cheaply.
> > >
> > > I still have a Genesis SM60 car amplifier which offers 2
> channels of 30w
> > > each.  Also got an SM100 which offers (you guessed it) 50w
> per channel.
> > >
> > > In reality, they were conservatively rated, and the SM60
would
> > > output nearer
> > > 45w per channel and the SM100 nearer 75w (4 ohm loads).
> > >
> > > Bridge the channels (2 ohm), and the things would drive
crazy
> > loads.  Only
> > > problem is that for say 150w RMS you need at least a 300w
> > supply.  300w @
> > > 12v = 25A.
> > >
> > > Lent the SM100 to my brother-in-law to drive his 15"
(or might be 18")
> > > homemade sub in briged mode - provided he could build a
power
> > supply meaty
> > > enough!!!
> > >
> > > James H
> > >
> > >
> > >
> > >
> > > ____________________________________
> > > Automated Home UK
> > > http://www.automatedhome.co.uk
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> > >
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> >
> >
>
>
>
>
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