Well I finally got the listening section of the room painted on the weekend and set the kit up for the first time. Here is the kit. Nad C 162 pre amp Arcam cd73 cdp Two Nad C-270 amps. Monitor Audio RS6 speakers. Monster 3600MRK11 line conditioner First I ran one amp, put on some very easy listening......seemed very nice....a little bright perhaps....new speakers and basically an emply room might be partially to blame. Thought I would bridge the two together and see if there is a difference..... Wholy jumpin jeezus......my volume control was hardly off idle and it was bordeline too loud......powerful to say the least. BUT......am I way off here, I honestly found the sound a little nicer with just the one amp and also a little more tame for lack of a better word/ Not to mention if someone ever gave that volume knob a dirty twist I don`t know if them speakers would recover from that thrashing. Anyways, my question is, is there really ANYTHING to gain by bridging the amps other than just more brute force in the volume department? I have actually listed one of the amps for sale which might have been a little hasty perhaps but can take that off the listing if no one commits to purhase. Am I too hasty in already considering sending one down the road? ps, I bought a IL Divo cd.......thats some good stuff right there.....can`t understand a word they say but I don`t need too......crank that up a little, tilt the head back in the chair and enjoy the dynamic concert......wonderful. I love this system but do I need the second amp?....I will admit, the second amp does look cool. Roger
It depends on how you do the bridging and speaker hook up. Separating the amplifiers into Left/Right mono-blocks has distinct advantages.
Most amplifiers are only doubling the gain to the input stages when you bridge them in parallel, this would give a three dB increase in overall level compared to a similar unbridged amplifier. Your amps might jump to +6dB which would be substantial but shouldn't be overwhelming.
If you're in a situation where other people have access to the amplifiers and you are uncomfortable with the increased level, you can add a step down device at the input to your amplifiers. They are well made by Harrisom Labs and sold through Parts Express or the Harrison web page. Choose between -3, -6 or -12dB gain.
I guess it just comes down to your personal preference Roger. When I had 2 NAD C272's I noticed a huge difference when running them bridged as monos. There was much better L/R separation and imaging. Even my wife said they sounded better that way.
Roger, pull the amp off of the listing. A couple of moments of listening to a brand new kit in a bare walls room and you have drawn conclusions???
You need to acclimate yourself to what you have, especially allowing the speakers to break in. The room needs to be tamed down or you will soon be listing everything for sale.
Give the kit the time it needs to settle it. Work with both one and two amp set ups, more or less get intimately familiar with what you have. As you add rugs, a sofa, some other furniture, perhaps drapes, the room itself will settle in for you. I would not buy or sell anything for the next two to three months
What happens if you were to sell your 270 and six months later you're out shopping for another one?
Well thanks gents. Between the basically empty room, new speakers and no sound suppression it can only get better, I just went out with my sons and picked up a couple more cds, perhaps I`ll grab a bottle of neck oil, head downstairs, bridge them back up and melt away with the Il Divo's and see if I like it better bridged now that I have been listening to it with just one amp....at least now I have A LITTLE something to compare it with. Roger Roger
I re read the replies to this thread and did some playing around. On the pre amp there are two sets of outputs......one fixed, which where I was and a another set which has a variable gain knob next to it. I changed from the fixed to the variable and I also bridged the amps and used the variable inputs to the amps. Set all three gain levels at the same position which in this case is 12 oclock..(half way) and has made the sytstem much more controlled and tame. the volume is not so agressive in its increase and sets my mind as ease in terms of an inadvertent throttle twist. My question is, am I loosing anything going this route in any way or am I doing something that I shouldn`t be? I will note however that after bridging the amps last night the music could be pin pointed to the speakers whereas the time spent running with just one amp the speakers disappeared. I preferred the listening experience much better when I couldn`t pinpoint the music. But maybe I`m not hooking the speakers up correctly. Also, bridging amps in mono mode, am I actually getting stereo?????? both amps read 'left channel' when bridging and both outputs from the pre amp go into the left channel inputs of the amps, not right and left. Roger
Hey Roger, that's interesting that you found that the imaging was diminished when biamping your speakers. I found the opposite result with my NAD amps when I ran them bridged and biamped.
And yes, when your amps are in mono, you're still getting stereo cause you're using two of 'em ;-)
What you might loose by using the variable input is for you to decide. You have to control gain somewhere in the system so the idea of another vc in the system becomes a fact of life if you need to trim gain. There are several ways to look at the issue of a variable control.
Ideally, you wouldn't have any control in the singal path and everything would always work out to be just the right level. That isn't going to happen so you'll have to use a vc somewhere. The advantages of reducing the gain at the amplifier inputs include running your pre amp vc at a more linear position on its rotation and having more control over fine adjustments to level. Additionally, you've increased the input impedance of the amplifier slightly which makes the pre amp's job a bit easier by running into this higher impedance load.
The major disadvantage in this arrangement is having too many places in the system where gain can be changed. If you are the only person likely to have access to these variable controls, then that becomes far less of an issue.
Listen to the system and if you can't detect any changes in quality with the gain control at 12 O'Clock, then don't worry. If you believe you do hear a change and it is not for the better - which I doubt - then you could have a technician replace the gain pot with a fixed resistor of the appropriate value.
There is no easy answer for your speaker issue. It is more common to have greater transparency when the amplifiers are working as mono pairs. Try some other set up changes to get back to where you were with one amp. Which set up changes? I don't know since I'm not in front of the system, but what you've experienced with the intial change to monoblocks is not normal.