Originally Posted by Nuance
I'll respond to the bold part. Did you miss the discussion where the left monoblock amplifier was found to be the cause of the distortion? If you think about it, it makes sense. The highest sensitivity speakers didn't exhibit it, or if it did it was minimal. Moving down the line into lower sensitivity speakers and lower impedances, the more prominent the distortion became. The SoundScape 10, being 84dB sensitive, 4 ohms and having the most expensive and resolving midrange drivers, was the one to offend the worst, misleading us into assuming it was a damaged driver. After careful driver inspection and testing at levels louder than we listened (with a more powerful amp), Jim found zero damage and could not duplicate the problem. Around the same time of Jim's discovery Terry stated his left monoblock had a bad transistor, and a call to the manufacturer Tuesday night confirmed it likely caused the issues we heard. That's not to say we didn't listen too loud and that some of the smaller speakers were struggling a bit being run full range at those levels in that sized room, but you get the idea. Peaks were at 95dB, but only the bass; other frequencies averaged low to mid 80's, with a couple songs having vocal or instrument peaks that hit the low 90's (this according to Terry's testing earlier this week). I'd be confident any of those speakers would have been fine for the most part if the amp wasn't suffering from that damaged transistor. Even better, if they were crossed to a subwoofer or two I'd bet they would have been perfect.
With that said, I would have calibrated to 75dB if I could do it over. 95dB was too loud, even if it was just peaks.
yes I read those thingshttp://www.avsforum.com/avs-vb/showp...postcount=1273
So for the soundscape 10's with 84dB sensitivity -- why wasn't the amp enough to hit 90-92dB peaks with a 96dB peak as a high in Terry's retest? I'm not saying it was sufficient - there was obviously something wrong!!! The numbers seem off to me though?!?!
84 dB 1 watt sensitivity
87 dB 2 watt
90 dB 4 watt
93 dB 8 watt
96 dB 16 watt
99 dB 32 watt
102 dB 64 watt
105 dB 128 watt
108 dB 256 watt (~ somewhere we get to amp limits)
then add distance calculation in there for Terry's room (which I have no idea how to figure indoors in his room)
Terry said he believed from retesting we were hitting 92dB bass peaks in most of the the bass portions with one peak at 96dB
I have a couple things I can't figure out with this info. Perhaps these concerns have answers???
1) Friday night we listened to Terry's speakers with some home theater demo material louder than anything we listened to on saturday during the actual demos and I noticed no distortion on Terry's speakers. True --- the speakers were using the fmod inline resistor to roll off frequencies at a rate of -12dB per octave from 70hz so this may be just the fact his speakers weren't having to recreate any bass ----- BUT then he also demoed the speakers for me without subs and I thought they were exceptionally clear on the black eyed peas track on friday night. On Saturday's meet from my listening position I could hear they were distorting a bit during the same song. On friday night I thought they seemed to be playing louder without distortion, and my videos I took seem to show the drivers moving more on Friday night than my video of them on saturday????? I don't know what to make of this at all. Terry said the left amp measured 1.5 dB less than the right amp. 1.5 dB alone sure doesn't explain what I heard if that's the only difference in left and right channels. Is there more problem than a 1.5dB deficancy?
2) Ignoring the Black Eyed Peas track - The 'distortion' I heard seemed to be mostly in the highs and midrange rather than the bass in on occassions in the orchestra and chorus music on every speaker I encountered -- which is a weird place for distortion to occur (rather than distortion in the bass sound)!?!?! I felt the mids and highs seemed to become less clear, blurred, distorted as the bass swelled in these dynamic peaks. The distortion sound was similar on these first speakers. On the Black eyed peas track it was definately the woofers distorting. By contrast, -the distortion sound on the Salk 10 was more of a warble which seemed to occur lower than the mids and highs. Whereas the other speakers just sounded a bit overrun by the material - the Salk 10's sounded like something was defective - which is why I got anxious and started talking to you guys by track 3. Amp or not - no matter what the cause of the distortion on the Salk 10 - the distortion sound was different in my mind during this demo.
Terry's comments linked above (as I read them) seem somewhat skeptical of an amp issue as it relates to the speakers outside of the Salk 10s. - based on ownership of these amps and post meet checkups. Given the decent wattage those amps provide and the levels we listened to and the guess that many of you run these speakers on less amp than Terry I'm sure - have you guys tested your speakers full range to see how they sound on your home gear? The fact that most people seem to have not heard the distortion on the Salk 10 completely baffles me. It was an irritating warble that I heard early on on the very first clip. Read my notes on that speaker written at the time of audition.http://i1191.photobucket.com/albums/...dScape10-1.jpg
It was very present and a different sound than the previous 'distortions' I had heard. I can't hardly figure how it wasn't noticed by everyone --- unless they were just sitting exclusively in front of the right speaker...
I really don't know what to make of it all, but I have a hard time blaming the amp on everything...Has Terry posted any more findings on the amp since the posts I quoted above?