2. amps-preamps
  3. 1040275897

What's My Problem?

OK, here's the situation . . . . hoping some of you with more knowledge and experience than I have can help me out.

On 2-channel listening, my system sounds great at low levels -- say at 9 o'clock or less on my VPC-1 passive preamp volume. Lots of openness and air, good imaging, lots of space around instruments. Of course, dynamics and bass suffer, but that's to be expected.

Between 9 and 12, the sound starts to get harsher and the soundstage begins to close up -- orchestral stuff sounds much more confused and congested. Above 12 o'clock, it's really not worth listening to.

These aren't very high levels -- 9 o'clock is my "late night with the wife sleeping down the hall" listening level, and 12 o'clock doesn't get Verdi's "Requiem" to real-life SPLs.

My first assumption is that my amplifier just doesn't have enough juice. But the RB981 puts about 200 wpc into a 4 ohm load, and I would think that would be enough to get to at least decent levels, even with my admittedly power-hungry NHT 2.3As . . . .

Alternately, I thought that maybe the 9000ES/RB981 combo wasn't ideally suited for a passive preamp. I understand that component matching is critical here, but I'm not really clear on how it works . . . . the volume gets loud enough with no problem, it's just that the quality suffers.

Then again, it could simply be "louder=more annoyance from digital harshness," and I need to replace the 9000ES with a better Redbook CDP. But it seems to me that if the CDP was to blame, the soundstage and "airy-ness" wouldn't change much as the volume increased.

Suggestions would be greatly appreciated!

Thanks!

Pat
tsrart
tsrart OP
79 posts
 
Sean --

I don't think it was the 981 if it was a recent review -- the 981 has been out of production for a couple of years. However, if a new Rotel amp had that problem, then an older one might have it as well . . . . I'll have to poke around and see if I can dig up any reviews of the 981 from when it was a current model.

Thanks!

Pat
amandarae
512 posts
 
Hello Pat,

How big is your room? It is possible that when the sound level increases(volume), you are hearing more of the early reflections of the leading transients (reverberation)than the primary sound from your speakers.

Proper speaker placement will help you here. I found a suggestion here at Audiogon recently about "Principles and techniques of speaker placement" it is on the net at Http://www.immediasound.com/speaker_set-up.htm

Hope this helps!
jameswei
883 posts
 
Could you be overdriving the amp's input circuits? If so, why isn't the volume very loud? All the connections are done right, including the speaker wires? Probably a dead end here -- sorry for the incomplete thought. Good luck.
gregm
3,415 posts
 
Or you hear the sonic effects of the volume pot on the passive, the impedance of which varies as you turn the volume up. I.e. a variation on what Sean suggested.
warrenh's avatar
warrenh
2,299 posts
 
Pat, It sounds to me that you have what's called plain ole amp clipping. Your amp is 200 watts per channel into 4 ohms. That's really not that much if your speakers crave power, as you say yours do. You realy want to consider the ratio of output powers when comparing amplifier power ratings. What you should be concerned about is your dBW level. Just because your 8 ohm amp (probably 100 watts per channel, right?) can give you 200 into 4, doesn't mean anything as far as your db level. You're probably getting less than you think db wise. I'm not familiar with your speakers, but I, too, have hungry speakers. (Revel M20s) Although I can go to 2 o'clock and I still don't clip. But then, again, I'm using a YBA Passion Integre, if that means anything. You probably will do better with 200 watts per channel into 8 ohms. Big decision: change the amp or the speakers. happy hunting. warren
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