Do you have to use a pre-amp with a power amp?

Barks · 4 Jul 2010 at 18:24

Hi guys,

Seriously tempted by this:
http://cgi.ebay.co.uk/NAD-C272-POWE..._HomeAudioHiFi_Amplifiers&hash=item2c557586b9

NAD C272
Outputs: Two pairs of 4mm banana plug/binding posts for easy biwiring
Amplifier power (watts): 2 x 150 watts (Continuous 4 - 8 ohms, 20,000 Hz <0.02% THD)
1 x 300 watts (bridged mono mode)
Number of channels: 2

1) Do I need a pre-amp or can this simply be connected to an audio source by phono?
2) If I do need a pre-amp can I use my current NAD C320BEE (integrated amp)

Many thanks

marl · 4 Jul 2010 at 18:41

You will need to use a pre-amp with this power amp. How else will you control your volume and select source inputs?

As for using your amp as a dedicated pre? I don't know. But if it can be done there'll be something to indicate this on the back panel.

lucid · 4 Jul 2010 at 18:44

You will need a preamp, and the integrated you have will do the job. Use the Pre-out sockets - that's exactly what they're designed for.

Don't try connecting a source directly to a power amp without some way to control the volume level. It'll be like running the system at 100% volume level all the time. There's a risk of blowing the speakers or damaging the amp.

Some CD player have both fixed and variable level outputs. I have a Denon CD player with the feature. But it sounds miles better going through my preamp.

Barks · 4 Jul 2010 at 18:49

I understand. Would you guys say this power amp is overkill?

The recommended amplifier power for my speakers is 150W and I've been running them on my C320 BEE (50W/channel) and they do go very loud albeit with distortion. Is there actually any advantage in running them with a power amp or are they designed for even more powerful speakers?

Cheers

lucid · 4 Jul 2010 at 19:32

It's not about raw power. It's about headroom.

Your speakers are capable of running with an amp up to 150W, but in reality your speakers don't actually need that much power to work. 1 Watt from your amp will produce between 86 and 92dB of sound at 1 metre depending on the sensitivity of your speakers. 88dB is enough to cause hearing loss with extended exposure. The thing about sound though is the loudness drops off quickly over distance.

What you get with a more powerful amp is better control of the speaker as a load and a bigger reserve of power (current) when the speaker is running at high volumes.

If there's distortion in your sound now with a decent 50W amp then I'd be tempted to address that first before investing in a bigger amp. The thing you really want to look at is distortion in the source signal. What's your main sound source?

After that, then it's a choice of either an amp upgrade like you are considering, or changing the speakers for something more efficient. There's pro's and cons with both choices.