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
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.
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.
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
believe it or not but it clips! don't pay too much attention to power ratings since measuring an accurate power ratings consumes too much time for the cheapo amp.
Two possibilities occur to me. The first, and I think the mostly likely, is that you simply are up against the limits of your speakers. My experience is that NHTs do get harsh and ugly as they get louder. Many less expensive (and some more expensive) speakers are like this, a notable exception on the inexpensive end being the Paradigm Reference range which usually sounds better as it gets cranking.

A second is that you are experiencing hearing loss, a sometime consequence of which is the development of rising levels of perceived distortion as SPLs increase. This would require evaluation by an audiologist but it is a very real and well documented phenomenon.

Let's hope it is the former, or one of the other possibilities identified above.

will