B&K harsh sound

I picked up a new B&K ST2140 2 years ago to mate w/ the B&K PT3 preamp driving some old Polk Monitor 10 speakers. The amp was awful out of the box. I burned it in 24/7 for a week. Still awful, harsh, glaring, distorted, constrained soundstage, you name it. I returned it.

My 20 year old Hafler sounded great. So it wasn't the pre, CDP or the speakers. I eventually got rid of the B&K preamp too. I'm not a fan.

Newer B&K amps sound quite a bit brighter, harder and more sterile than their older counterparts to me. Rotel gear is also somewhat bright, but may be slightly smoother overall.

Having said that, you should have any electronic component that you bring home for audition on for at least 3 days straight. If at all possible, music should be running through the system 24/7 before doing "serious listening". When running the system during this time, low volume is better than no volume and no volume with the power on is better than no power at all.

Not only are we trying to establish thermal stability, but we are trying to pass signal through all of the components that will normally see such operation. Granted, the compononents might not be getting the work-out that they would during normal use and at higher volumes, but something is better than nothing.

If you don't like the sound of what you hear after 72 hours of continuous playing, you probably never will. Things can change after that, but with electronics, you're about 90% of the way there after this period of time / operation. If that last 10% that settles in over time makes or breaks your decision, you're walking a very fine line.

Speakers will continue to alter operation for quite a period of time, especially if you listen at low levels. I have purchased used speakers that were over a dozen years old that still weren't broken in. Throttling the power to them on a sustained basis made a DRASTIC difference in low frequency output. This was because the suspension on the woofers was never stressed and was still "tight" due to never having to make long excursions. Pumping more power through them / playing music that had "basso profundo" made a huge difference after several days. Speakers that were recently re-foamed may also go through a similar "break-in" period all over again. It is not quite as severe or noticeable as with a brand new speaker, but it does occur. Sean
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Thank you everyone. I am now wondering if I shouldn't give the amp another try. I actually wondered if it might take more than the 2 hours I gave it to come to life. But that's all the time I could spend with it. I should have left it in the system, even if I was just watching tv, and tried listening again after a day or 2. Someone asked about speaker cables. I am using Synergistic Research Alphas left and right and a new Wire World Oasis v center. I have heard others describe Rotel as having a "bright" sound. My amp does not come across that way, but on the other hand, I've been using it for years and years.

Sean has the right of it.

Let the amp burn in 24/7 for at least 2 or 3 days (don't power it off and on). Then see how it sounds. 2 hours is not enough.

I had a B&K ST1400 that your amp is based on and it was anything but harsh. In fact, the ST1400, like many MOSFET amps, was hardly the last word in transparency and "air", it was quite mellow and warm sounding, even slightly rolled off at the very top of the treble - IMO not necessarily a bad thing considering the speakers & front ends it's likely to be paired with.

Despite the howls from some quarters, I've found burn in to be a factor with most components. My CD player sounded OK out of the box but took about 200 hours (continuous hours, friend) to attain anything like its optimum sound. Bob Crumps power cords famously take a month to burn in. (But they're very entertaining/frightening meanwhile - it's like buying five different PCs in one.)

PCs can make a difference too.

Maybe the B&K was a defective amp or maybe you had a system mismatch. (Synergy is the thing in audio and, as pointed out, not all components mate well together.) Or maybe the B&K sound has really changed that drastically in the last 5 years. But I'm surprised the B&K sounded night and day different from your Rotel. Nevertheless, when all's said and done, you may simply end up preferring Rotel amps, or even preferring what you're used to listening through.

It could be that I am used to and enjoy the sound from my little Rotel. That causes a problem in the power department though. I clearly need more reserve power.