Bricolo
Make sure you listen to a 'before' and 'after' version. And be careful not to get glue onto exposed pins and conductors - it's certainly not as good a dialectric as air. Also as Peter Daniel noticed, excessive damping somehow kills the sound, whether you overdamp a turntable, an arm, or an amp the result is quite similar. Btw, some people prefer overdamped sound. Just last night i helped a friend troubleshoot a valve phono built by holding all caps and ground planes in silicone and the smaller caps/resistors/wires in P2P. Seems like a very fast and secure way to build and didn't sound bad at all.
Thanks SY but I'm actually at Brown...just from Berkeley originally 
With regards to all these postings...So far I'm going to have to agree with Circlotron on this. From what I’ve gathered so far, people want their amps to sound better when they put more time/effort/money into them. That’s totally ok by me but I’m still trying to figure out if there is a quantitative explanation to this question. Microphonics will not affect a semiconductor especially a GC chip. As far as the "vibrations" everyone is talking about. Are you talking about vibrations induced from the speaker than then rattles the amp or from something else? The only possible way semiconductor amp will affect sound via placement in a room is perhaps if the physical box causes dampening/interference from the speakers..ie putting the amp directly in front of the speaker so as to block the drivers...this is much in the same way that if you listen to music with pillows in front of your speakers it won't sound too hot. I think some of you are suggesting that the actual box of the amp affects the acoustics of the room. While this is very true, everything affects the acoustics of a room, I doubt that anyone (at least I can't) can hear a difference due to just the acoustics as a result of chassis material. I think you'd hear more of a difference if a guy weighing 500 lbs was in the room with you than if your case were made of aluminum versus a paper bag. If you want to tell me that putting the amp on the floor/upside-down/on the speaker etc will actually produce a different signal then I don't really know what to say to you...read an engin book? Rotating/positioning the chassis will not induce a better/worse signal. Again, I’m not trying to offend anyone, I’m just trying to find a quantitative explanation for why the cassis made of aged oak wood soaked in the Egyptian Nile for four months and then dried by local villagers “sounds better” than the chassis made from wood soaked in the Euphrates river and dried by the locals over there. Thanks to everyone replying though.
With regards to all these postings...So far I'm going to have to agree with Circlotron on this. From what I’ve gathered so far, people want their amps to sound better when they put more time/effort/money into them. That’s totally ok by me but I’m still trying to figure out if there is a quantitative explanation to this question. Microphonics will not affect a semiconductor especially a GC chip. As far as the "vibrations" everyone is talking about. Are you talking about vibrations induced from the speaker than then rattles the amp or from something else? The only possible way semiconductor amp will affect sound via placement in a room is perhaps if the physical box causes dampening/interference from the speakers..ie putting the amp directly in front of the speaker so as to block the drivers...this is much in the same way that if you listen to music with pillows in front of your speakers it won't sound too hot. I think some of you are suggesting that the actual box of the amp affects the acoustics of the room. While this is very true, everything affects the acoustics of a room, I doubt that anyone (at least I can't) can hear a difference due to just the acoustics as a result of chassis material. I think you'd hear more of a difference if a guy weighing 500 lbs was in the room with you than if your case were made of aluminum versus a paper bag. If you want to tell me that putting the amp on the floor/upside-down/on the speaker etc will actually produce a different signal then I don't really know what to say to you...read an engin book? Rotating/positioning the chassis will not induce a better/worse signal. Again, I’m not trying to offend anyone, I’m just trying to find a quantitative explanation for why the cassis made of aged oak wood soaked in the Egyptian Nile for four months and then dried by local villagers “sounds better” than the chassis made from wood soaked in the Euphrates river and dried by the locals over there. Thanks to everyone replying though.
You've never had the chance to live with a nice system for a while, right? Whether diy or commercial. The higher the resolution of a system, the more capricious it becomes in everything. And yes, you can clearly hear effects of boxes/support structures on headphones.
Yes, semiconductors are sensitive to vibrations. Before i noticed this i never used to pay much attention to heatsinking and how detrimental it can be from vibration POV. Eventually (we're talking ancient history here - early 80-s) i built an amp with a cheap-skate heatsink made out of multiple layers of 0.3mm alu bent to create large surface area. Transistors were old trusty 3055/bdx18. When you put the volume up you could clearly hear the transistors 'sing' through the heatsink. Obviously the reverse effect is also possible.
Even if you choose not to believe this story the GC uses elcos which are clearly and measurably microphonic.
The way i see it, it's very easy to illustrate that most components in an amp are to a degree sensitive to vibrations. The real argument between the camps is whether this degree is audible or not.
There are so many variables in a hi-fi system that we could never resolve all the arguments if we sat at our keyboards for a hundred years.
This is one case where the time we spend arguing could be better spent preventing as much vibrartion as possible from reaching the components. If it makes no difference then it shouldn't do any harm and if it does, then we will have better sounding hi-fi.
The key issue here is understanding the difference between minimising the vibrations and over-damping components that will result in a 'dull' sound. Experimenting is the key to success here, not arguing.
Yea i come from an engr. background also, I am proud ta have gone ta Texas A&M, i am proud to be an aggee(sorry) proud to be an agie(sorry) proud to be an agye(sorry), anyway proud to have gone to Texas A&M.
Really i have found a slight difference in cab materials insofar as the sound, BUT i pot all my circuits in silicone and dampen (actually isolate) the H/S.
Try this experiment, place a lead weight on the chip , you know one of those weights with the stickem backing for wheels, and listen to the drastic change in sound. It dulls the sound to a great degree.
As far as cabs all i use is alum. (for my friends)(hammond)and i make my personal ones out of wood as i like the look and i am an old speaker builder anyway.
I get better sound from rigid, heavy, small cabs using the GC.
ron
Really i have found a slight difference in cab materials insofar as the sound, BUT i pot all my circuits in silicone and dampen (actually isolate) the H/S.
Try this experiment, place a lead weight on the chip , you know one of those weights with the stickem backing for wheels, and listen to the drastic change in sound. It dulls the sound to a great degree.
As far as cabs all i use is alum. (for my friends)(hammond)and i make my personal ones out of wood as i like the look and i am an old speaker builder anyway.
I get better sound from rigid, heavy, small cabs using the GC.
ron
Maybe with a given amount of microphonics we are getting into that old SET thing of second order harmonics?Hay if it sounds good keep it.
I believe the support bar MAY (<---keyword) be better, it kinda depends on the whole structure and the methods used to either dampen or isolate or dampen/isolate< my fav.
After having to witness many monitored dynamic tests of circuits at the lazy B ranch (Boeing aerospace) i can assure yall that structural vibrations do affect the performance of chips and component assys.
ron
I believe the support bar MAY (<---keyword) be better, it kinda depends on the whole structure and the methods used to either dampen or isolate or dampen/isolate< my fav.
After having to witness many monitored dynamic tests of circuits at the lazy B ranch (Boeing aerospace) i can assure yall that structural vibrations do affect the performance of chips and component assys.
ron
This is a really interesting thread on a subject well worth stirring up.
I'm intrigued by the idea that different case materials can be detected over headphones. It's also worth saying that unless you're testing this sort of thing via a double blind test, you're not really testing it ... Psychologists know that experimenter effects and the placebo effect are extraordinarily powerful.
As far as vibration goes, an easy test is to turn up the volume (with no music playing) and tap the case, components, wires and see what comes out of the speakers.
Another interesting experiment is to play a set of test tones over the speakers and see what hums and buzzes along in the room, although persuading your significant other that you have to ban all ornaments from the listening room can be tricky.
Another thought - has any one tried the trade off of installing a Gainclone in the speaker cabinet to reduce the length of speaker wiring vs the risk of increased vibration?
Colin
I'm intrigued by the idea that different case materials can be detected over headphones. It's also worth saying that unless you're testing this sort of thing via a double blind test, you're not really testing it ... Psychologists know that experimenter effects and the placebo effect are extraordinarily powerful.
As far as vibration goes, an easy test is to turn up the volume (with no music playing) and tap the case, components, wires and see what comes out of the speakers.
Another interesting experiment is to play a set of test tones over the speakers and see what hums and buzzes along in the room, although persuading your significant other that you have to ban all ornaments from the listening room can be tricky.
Another thought - has any one tried the trade off of installing a Gainclone in the speaker cabinet to reduce the length of speaker wiring vs the risk of increased vibration?
Colin
There's an even better way. Put a resistive load on the amp instead of the speaker and play some music. You will most probably hear all sorts of (low level) buzzes and vibrations from the case and especially the heat sinks. Different materials, different construction, different buzzes. Is it audible with speakers? Depends.
jan Didden
jan Didden
Nuuk said:
Will it? Are you sure?
If you're making a sound-producing component - e.g. a violin body, a speaker cone - damping its resonances may indeed make the sound dull. At the extreme, say if you encase the whole lot in epoxy resin, it makes no sound at all.
To say the same applies for electronics is not at all obvious to me. If you take as axiomatic that, for example, an amplifier should not deviate from a flat frequency response, how does allowing components to vibrate support this aim?
Cheers
IH
Nuuk said:
I'm more concerned with creating pressure on a chip's case (by attaching a bar on top it two screws on ea. side) than with material used for such bar.
So far I didn't had a chance to experiment with that, but somehow my feeling is that the pressure on a plastic body may create unwanted effect. Any comments?
Don't kill me
IMHO/imagination, mechanically speaking, sometimes when the case of a unit is very firmly secured on a vibrating surface, the components inside the unit may vibrates more than the surface. But if the unit is just firmly secured not loose, the components inside may vibrates equal to or less than the surface, relativity motion?
Of course I have no proof of any of the above, some how it just seem logical to me
Chris
IMHO/imagination, mechanically speaking, sometimes when the case of a unit is very firmly secured on a vibrating surface, the components inside the unit may vibrates more than the surface. But if the unit is just firmly secured not loose, the components inside may vibrates equal to or less than the surface, relativity motion?
Of course I have no proof of any of the above, some how it just seem logical to me
Chris
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