Better to start with a 2ch or 5ch amp?

[george_k]

I'm planning an amplifier upgrade on a budget that could afford either an RB-1080 or an RMB-1075.

At the moment I am using a NAD T742 which does an honest 50wattsx5. My setup consists of a pair of B&W 603's and 2 small paradigm atoms as surrounds (no center, no sub). I think I will use the NAD as a processor for now until I can afford to replace it with a proper processor.

I'm planning my upgrades as so:

step 1: purchase amp (2ch or 5ch)
step 2: replace 603's with 805's
step 3: purchase a sub
step 4: purchase HTM1 center channel
step 5: purchase two more 805's
*step 6: purchase amplifier to drive the rears if a two-channel amp was purchased in step 1.

I don't see steps 4,5 and 6 happening for aleast another 3 years maybe more...

Should I purchase a 2 channel amp for now or a 5 channel? or should I just wait and save for an RMB-1090? (the paradigm atoms already get enough juice from the receiver)

[thyname]

I think you should purchase RB-1080 now. You can always use it later to power your fronts in a surround setup, it will give you a good stereo sound, even if your future surround receiver is not that powerful. At least, this is what I always plan to do, as I only have a stereo system, but planning to have a HT once I move from apt building.

[rhoffman000]

I would buy the speakers and the sub first. That will give you the most noticeable improvement in sound the fastest.

[george_k]

rhoffman000,

I don't think 50watts is nearly enough for the 805s, in fact it's listed as the bare minimum on the B&W site and they are a more difficult load to drive than the 603's. So the power amp will have to come first.

[Jamil]

Go with a 2 channel amp first. I agree the NAD T742 will not do justice to the 805's. I also see that you mention RMB-1090 in the last sentence. Did you mean to say RB-1090 instead? If yes, then I would recommend trying the 1080 and 1090 with the 805's in a store with your music. That will give you a hint whether to get a 1080 now or wait and save for 1090. Another thing to keep in mind. Rotel is not planning on keeping the 1090 in their line and according to my dealer that particular model is close to being discontinued. New digital amps will be coming out with more juice than that beast of an amp Good luck!

--
Nasser

P.S. I upgraded to a 1090 from a 1080 couple of weeks ago for my power hungry Dynaudio fronts. Will go the digital amp route later if they are infact true and hold on to their billing. Don't want to be the guinea pig for Rotel's step into the digital amp world

[RebelMan]

george_k, how much time do you see between getting the amp in (1) and upgrading your speakers in (2)? If you can wait, save your money and do both at the same time. Not only will you curb the upgrade bug longer this way but you might even get a better deal from your dealer. If you can't wait, then get the RB-1080. It's cleaner than the RMB-1075 and it will make the most of your 805's when you do get them.

[george_k]

I figure that if I get the amp now, I should be able to afford the 805's by December or January.

[GregoriusM]

2 channel, at least the 1080, preferrably the 1090 if you can afford it, then you are set for a long time, and can "play" around with just about any dang speaker you want.

Then the 5 channel amp at the end.

I'm also assuming you have decent input components to match the speakers you are moving up to. Don't forget to consider those inputs when doing your upgrading.

Garbage In, Garbage Out. GIGO!

IMHO!

[rhoffman000]

As it's been stated before, doubling your watts only gets you 3 dbs in sound. So going from 50 watts to 200 would only get you an extra 6 dbs. While you will want those DBs eventually, I would think getting the 805s and a sub now would be much better than your current setup...and adding a better amp later will be like icing on the cake. Unless the 805s have an abnormally low sensitivity, I don't know why a true 50 watts shouldn't power them to a reasonable listening level.

[PewterTA]

I've heard the 805s on a 50watt x 2 amp (can't remember what amp it was off the top of my head)...

To be honest, I thought they sounded very weak and aneamic is the only words that come to mind. I then hooked them up to my RB-1080 and it was amazing the difference. Like you had removed a concrete wall between you and the speakers is the best I can put it.

An amp will make your current speakers sound so much better, which is worthwhile, while you try to get your new speakers. If you get the speakers first, their performance can be limited to by what's pushing them, which could or could not make you happy with how they sound, and can put a slight regret into why you purchased the speakers in the first place...this will lead you to wondering if you should've bought other speakers.

To me, the safest bet is to buy the amp, enjoy what differences it makes in your current speakers. Then once you have the money, you will notice the difference the speakers make (not amp and speakers). So in each case you can hear the difference that each piece of the "puzzle" makes.

[george_k]

rhoffman000,

As it's been stated before, doubling your watts only gets you 3 dbs in sound.

I pulled out my old book on Acoustics to verify this (see Fundamentals of Acoustics, 4ed by Kinsler & Frey et al). You would need an 8-times increase in intensity in Watts/m^2 for "twice as loud". For example:

If you had a 5 watt amplifier you would need to increase this to a 40 watt amplifier for "twice as loud" or if you had a 25 watt amplifier you would then need to increase this to 200 watts for "twice as loud". SPL = 20log(P/Pref) so for "twice as loud" you'd need to increase your P by approx 2.8 times greater than your Pref and that corresponds to about a 9 dB increase in SPL.

Yes my current 50 watt amp can play at over 90dB but that is really pushing its limits as any increase in loudness in the music/dvd might cause the amp to distort as it has no headroom.

One more thing I should mention is that the sensitivity rating of the 603s is 91 while on the 805's its 88dB.

[RebelMan]

Keeping in mind that music is dynamic, the xxx watts an amplifier is rated at is for continuous power, not dynamic. Better amps have far more headroom to allow for greater demands. The RB-1080 is actually capable of generating 300-400 watts of power, on an 8 ohm load, for extended periods of time when needed.

While a 50 watt amp will drive the 805's the demands placed on it would be too great. Overheating and distortion will set in very quickly because of our insatiable appetite to crank up the volume. Not to mention the amp's lack of efficient damping of the mid/low frequency driver.

george_k, I have the RB-1080 and I drive my 803S's with it but, just for kicks, I also paired it with my SCMS's (in the same room and location), which are very similar to the 805's. I can describe the feeling I got in two words... "awesome volume". Not quite the presentation of my 803's (obviously) but I was impressed nonetheless. Get the RB-1080 and add Step 6 to your plan. You won't regret it!