CurtPalme.com Home Theater Forum

Zebu Fellenz · Joined: 21 Dec 2006 Posts: 2567

Hey Guys,

Like I said in another thread I'm looking either for a better receiver or some power amp(s).

I came across a NAD CI9120 on Craigslist last night. It's obvious that this is a lot more amp than I need right now being 12 channel at 80WPC but the way I see it this would allow for bi-amping if needed and also extra channels that I could use to drive passive subs.

Is there any major reason to NOT look at and bring this amp home? The asking price is $340, that's less than $30 a channel. Smile

Here's the spec sheet:

http://nadelectronics.com/content/100420140633-CI_9120.pdf

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

I have an older model 2200 power amp; 2 channel. It will rock the most power hungry speakers!

NAD made good amps way back when; not sure if they still do or not.

wallace

ecrabb · Posted: Tue Dec 21, 2010 4:29 pm Post subject:

The 2200 is a nice big 100wpc stereo power amp with big dynamic power capability...

I don't know about the CI9120... That amp is a custom-install unit for whole-house audio, so it's designed to drive a bunch of small wall- or ceiling speakers over long cable runs... I don't know if it would have the same kind of dynamic power or current capability that a dedicated power amp does... I mean, that amp has twelve channels packed in the same space as the 2200 has two channels. In fact, I highly doubt it would be a good solution.

Not sure, though.

SC

Zebu Fellenz · Joined: 21 Dec 2006 Posts: 2567

**Curt Palme** · Posted: Tue Dec 21, 2010 5:01 pm Post subject:

The audiofools will disagree with me, but to me, an amp is an amp is an amp. A watt is a watt, when dealing with RMS ratings.

I agree, for HT or stereo use that's going to be cranked, 80 WPC is a bit low. Also, that 80 WPC is rated at 6 ohms, so figure on closer to 65 WPC at 8 ohms.

If you're interested, I have this amp for sale for cheap:

http://www.canford.co.uk/Products/93-729_INTER-M-QD-4960-POWER-AMPLIFIER-4x-170W8-240W4-bridge-facility-rackmount-2U

2 racks spaces, 4 channel, and you can bridge 2 channels for double the power.

I use two in my HT with zero issues, they've been on 24/7 for 8 years now.

$225 plus about $45 to ship to you.

Zebu Fellenz · Joined: 21 Dec 2006 Posts: 2567

Hey Curt,

A few quick questions.

Currently I'm only running two channel in my theater, I'm using my Rotel RX-404 which is rated at 30WPC, this receiver will easily drive my speakers louder than I care to listen and I've never heard any distortion, clipping or anything else that would lead me to believe I was overdriving anything.

With this said I would think that even 65WPC would be more than adequate for my needs. I have a small room, roughly 15'x15' with 7' ceiling.

Now my next question is about bridging. From my understanding bridging simply throws a switch to send a signal to multiple amp sections and then routes the output to a single set of output terminals, right? Anyway, if my understanding is right wouldn't I be able to split an input going into this 12 channel NAD and then combine the outputs to get ~130WPC when I need more power? Or am I misunderstanding?

I'll keep that Inter-M in mind, I was looking pretty hard at it the first time you had it listed on the forum. Smile

Erik

**Curt Palme** · Posted: Tue Dec 21, 2010 5:29 pm Post subject:

If the Rotel has an analog volume control, max power is reached at about the 11:00 position. Any louder and you're clipping the amp. Also keep in mind that the human ear is actually not very sensitive to distortion, 3% is what I've heard. So by the time you hear distortion, you're way into clopping the amp, and possibly damaging your speakers.

Twice the power is only a 3db increase in volume, which really isn't much at all. Finally, it's far easier to damage speakers with an underpowered amp as compared to too much power.

AS for bridging, what happens is that the signal is indeed sent two two individual amplifiers, and you put the speaker between the two positive terminals of the two amp sections. When one amp pulls, so does the other, and both push simultaneously as well, giving usually about twice the power to the one speaker. If the NAD doesn't have bridging switches, the amp may not be capable of being bridged.

Zebu Fellenz · Joined: 21 Dec 2006 Posts: 2567

Thanks Curt,

Yes, the Rotel has an analog volume control, I usually just set it to the 12:00 position and control the volume externally. If I turn it back to 11:00 it's still plenty loud, I'll leave it there from now on so I don't have to worry about clipping.

Thanks for the explanation on bridging, sounds like this NAD isn't capable of being bridged and probably wouldn't be well suited for what I want to do.

I think I'll keep looking.

Thanks!

Erik

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

An amp is not an amp, is not an amp, is not an amp. Wattage was not the major factor I considered when when I bought my 2200. I was looking for (and got) an amp that would handle low resistance ratings and have high amperage output.

The Infinity RS-II speakers are power hungry to say the least.

wallace

**Curt Palme** · Posted: Wed Dec 22, 2010 3:16 am Post subject: