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

Showing 4 responses by tsrart

tsrart OP
79 posts
 
Audiokinesis --

Disregard my last post. The 2.1s do, of course, have a midwoofer that is different from the two woofers. I was thinking of the fact that their mids are the same as the OTHER NHT speakers I have . . . .

Pat
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
tsrart OP
79 posts
 
Wow -- thanks for the great response!!

I've got some more info:

I had an idea that I SHOULD have had earlier, but didn't think of until I saw Warrenh's post mentioned changing amps OR SPEAKERS. Well, I have three other pairs of NHT speakers in my HT rig, all of which are 8 ohm and easier loads to drive than the 2.3As. I picked the 2.1s, which are full range and with almost the same driver complement as the 2.3As, but with a slightly shorter cabinet and an 8 ohm impedence.

I moved out the 2.3As and put the 2.1s in the same spot -- didn't tweak them, and the 2.1s don't have the NHT Spike Kit bars on the bottoms, either, but I figured it would give me an idea.

It did . . . .

The 2.1s absolutely blew the 2.3As away. The soundstage started big and got BIGGER as the volume increased, the harshness was noticeably decreased, and the bass was much more solid, in spite of the fact that the 2.3A is supposed to go lower . . . .

So I think we can safely say that the problem is some sort of issue with the Rotel driving the 2.3As. I'm going to play around some with your other suggestions, including going back to A/B through the Lexicon. Gs5556, I think the input impedence of the Rotel is 27K, although I am using 2 foot interconnects with a fairly low capacitance between both CDP/preamp and preamp/Rotel.

I'm going to be annoyed if it's the preamp . . . . just bought that, and I really like the sound (or lack thereof) with it in the system as opposed to the Lexicon . . . .

I'll keep everyone posted, and again, thanks VERY much for all the help!

Pat
tsrart OP
79 posts
 
Audiokinesis --

That's really interesting . . . . could that explain why the 2.1s sound better than the 2.3As? The 2.1s have three identical 6-inch woofers and a tweeter, while the 2.3As have two identical 6-inch woofers, then a DIFFERENT midrange, then a tweeter. Seems like three different drivers would allow for more "mismatching" than two different types of drivers . . . . How do speaker manufacturers get around this issue?

Seandtaylor99 -- those are good ideas. I'll see if I can dig up an active preamp somewhere to try out. I don't think I want to experiment with running the 9000ES direct into the amp, since I don't think I have any CDs that are quiet enough for long enough to do a real test listen.

Bluefin -- Also good ideas. I think that if it DOES turn out to unquestionably be the passive that's the problem, I will swap preamps rather than trying to swap amplifiers and/or CDPs.

Marakanetz -- Thanks for the suggestions! I think I'd like to stay with NHTs, though, since my whole home theater is built with matched NHT speakers. The Creek would be an option, but that would be harder to integrate into the HT system than sticking with the Rotel amp I have (or another Rotel with more power) and changing preamps, if necessary.

Again, thanks to all!

Pat
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