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In Reply to: RE: Bryston comes through... posted by Jim Pearce on June 25, 2016 at 08:34:09
"Noticeably quieter" in what way? i.e. mechanically or sonically[I was thinking of maybe changing a 4B-SST2 to a SST3. No good reason.... There's a fairly large diff between SST and SST2 BTW, supposedly not so much between SST2 and SST3. You sure are right about how much prices have increased in a relatively short time. Abe mentioned this recently too, I was surprised myself.]
Sorry, I mixed up two topics in my mind. I am asking my question while thinking about a 9B-SST2. It is similar in some ways to the 6B in that there were not as many changes made going from SST->SST2 as the other models, apparently due to module space. My 9B-SST2 is also so "old" (early '09 build) that it's slightly different than later/current models. I think it is biased to run in class A a little bit "too much", it rarely comes out of it for my loads/levels.
The "problem" is when the module temp gets >50degC, some of the transformers buzz a bit (i.e. mechanical noise). You can only hear this when you stick your head in the rack, but it's something that doesn't belong so gets the anal audiophile's hackles up...even though it's supposedly harmless.
I am about an hour's drive from the factory, they'll adjust the bias under warranty (best guess, since they won't have *my* operating conditions), but apparently don't mind if I do it myself. I was kind of wondering if that might be what you meant by "noticeably quieter", like if it was less mechanical noise than before, perhaps they adjusted the bias.
Edits: 06/25/16Follow Ups:
No, I can't stick my head in the rack...no room. I probably run class A most of the time with 5 channels into Paradigm 100s and a 15" sub-woofer. I put on End of Days on Fibe because my wife likes the goofy action and I like the soundtrack, and it was definitely quieter and more detailed.My brother just upgraded his 4B ST to an SST cubed. Of course that's a massive difference especially in a stereo system over Martin Logan speakers. He got a very good deal from Audio Eden, less than $3000 with tax on trade as I recall. It isn't clear at this point whether there will ever be a 6B SST cubed. Since my system gets used mostly for TV, movies and Jazz FM these days I'm not sure I could even contemplate the upgrade.
Edits: 06/25/16
Thanks for the reply, didn't want to make my "problems" your problems, was just looking for more...observations.Looking at some measurements I made in early '15, when it was cooler ambient, and putting them together with those I made last week, I sort of retract some of the things I say. Or at least put some more ???s around them.
My thinking now is the (my) amps were designed, or set up, to run at the temp they do. This is their natural operating temp. No load or a "heavy" load, that's the temp they eventually reach (1-2 hours) and settle at. Even with a ridiculous-sized fan blowing or sucking over the amp, all it does is forestall the inevitable.
I bet they slightly reduced the bias in later builds of the model. It is a very low noise though, probably nobody cares, it's not like you can hear it in any real-world listening situation. It's just so damn hot though, but not like "touching a tube" hot. Much ado about nothing most likely, I just like to make sure everything's working properly and longevity isn't compromised etc., and this amp has been working this way for > 7 years so far.
The 6s are similar in one design way in that the heat sinks are "internal", unlike the (cool-running) e.g. 4s with their large external heat sinks. Not a lot of (simple) options for dispersing the heat beyond convection for the relatively little bits of heat sink that peeks out on the 9s.
Yeah, I only use the 9 for movies, very little mch music in comparison, it does the surround channels. Except for maybe the center ch, it just lazes along most of the time.
Edit: oh yeah, all the speakers my 9 is driving are Paradigms too. Re the 4B-SST3, it's hard to go wrong with the 4. Maybe not to everyone's sonic taste, but a solid choice nonetheless. I had the chance when I first got my 4B-SST2 to compare with the SST and ST 4s. I kept the ST and sold the SST because I could get far more for the more-current SST. The ST is still here, waiting for a proper job. I had planned to use it for sub duty, but ended up going a different way. Maybe some more Atmos channels, any excuse...
Edits: 06/26/16 06/26/16
I don't know what's up with your amp, but my 6B SST runs pretty cool. I had the air set at 21 today and the warmest spot on the right side of the amp was 25 running Jazz FM. After several hours of 5 channel and 3 channel TV it only rose to 26. Barely warm to the touch. My 4B SST - which only powers the surrounds - is very cool. My 3B ST (Awaiting future use: you aren't the only one!) used to heat up quite a bit.
I know, my amp ain't right!But it sounds fine. I like hot SS actually (to a point), so complaining about it is a bit twisty for me. The thing about the hot is it's enough to (indirectly) make the toroidals buzz a bit, that's what's been making me think it's "too much".
"Bryston" said when the trannies buzz, it means to back off on the bias. So it's not like they haven't heard of this, though very few web mentions. There is some temp sensor apparently involved in the biasing too, but I don't see an obvious one in the schematic...maybe he meant on the larger/non-modular amps.
The 6s have very substantially larger heatsinks than the 9s, whose HSs are really quite small. Obviously not *too* small...
I replaced my original 4/9B-ST combo in the HT with the SST2 equivalents. I honestly don't remember how hot the STs got. I had a 3B-ST before that driving Maggies and it did get quite hot. That's the only time I've ever seen clipping indicators on one of their amps, so went to the 4B-SST and have never seen since. Which reminds me: the LEDs of the 6/9 go orange when in thermal overload? I've never seen that either.
Edit: FWIW I played the John Wick BD (don't necessarily recommend the *movie* itself...) at reference level (about 3-4dB louder than I prefer) yesterday and the 9B-SST2 heat sinks were "untouchable" for more than 2 seconds, that hot, I'd guess in the 60s degC. Then I played the Mad Max BD at a similar level. Both these movies have "boisterous" surround levels, so give the 9 a bit of a workout for a change. No problem sonically, no smoke...
More: got the 9 on the kitchen table now (too heavy/awkward to carry downstairs to the bench) and warming it up for 1.5 hours to reach its typical temp. Top removed (lots of T8s, no need to remove modules to check/adjust bias), heat sinks are bigger than I suggested after all, things look much larger out of the rack...bias values appear ~normal so far, but when the amp is "cold" isn't the issue so we shall see.
Just to finish the story: bias is fine after 3-hr warm-up, pretty much within spec considering my Fluke is only within 2mV down there (0-5mV variation), but I barely touched them so they looked "correct" on the meter anyway. So then: that's the temp the amp is designed to run at, in rack or in open air it's the same. I think I figured that already... :)
But one thing I found: the *extremely* tiny trannie buzz I can hear out of the rack seems to be amplified by where the amp is in the rack in the room (corner-ish). The amp was on an isolation platform, which I've removed for now. Also there were two screws on the bottom of the amp case that were loose (haven't moved the amp in > 7 years) and rattling, that's how I found them. Weird, all the other T8s were extremely tight; vibrated loose??
Edits: 06/27/16 06/27/16 06/27/16
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