| Vikash |
| Can I build a chip amp case using plastic, or must it be metal for shielding? |
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| Frank Berry |
You can use a plastic case for your amplifier but you'll need to provide metal heatsinking for the IC's.
Actually, metal is better for the case. It also looks much better. |
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| Vikash |
Well I don't have the tools to do good metal work yet, but I have a picture in mind for an open/exposed design using transparent plastic for the top and bottom in a kind of curvy x shape. Similar to that record player, you know the one...
I'm not experienced enough to know if I'm making a bad compromise going away from metal though. Naturally there will be big chunks of metal for the heatsink ;) |
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| Frank Berry |
Just make sure that you have provided enough airflow around the heatsinks.
it would be a shame to see your work of art melt because the metal heatsinks were sealed in a plastic enclosure with no ventilation.
Show us photos as your work progresses! |
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| chris ma |
Same here metal casing is very expensive for me and not enough experience with metal so I choose to be cheap and use MDF, plexiglass is not cheap and wrap over time.
paint any texture you like
;)
GC number two in the making...
Chris |
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| Nuuk |
My first GC's were built in plastic tubes (100 mm soil pipe) although I lined the inside with kitchen foil for shielding.
Wheher you need shielding or not depends on what interference you are susceptible to. I have had one of my amps running here for about four months on a plank of wood with no shielding and with no problem. ;) |
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| Vikash |
| Great news. This opens some more practical options to me. Well here's a preliminary idea... |
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| lgreen |
| Plastic is ok, but if you want to use a metal one, You could get some nonworking stereo components and "gut" the innards from them, and use the case. I did this with an old Kyocera CD Player/ Gainclone (posted on diyaudio here ) |
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| Vikash |
| I'm quite getting into this... |
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| carlmart |
| quote: | Originally posted by Vikash
Can I build a chip amp case using plastic, or must it be metal for shielding? |
Plastic is OK, as well as wood. As long as there's little RF close to the amp.
Besides the obvious radio emissions from your city broadcasts and how close you are to any transmitting antennas, there's emission from several things. Like computers, fluorescent tubes, monitors, dimmers, motors, etc.
Proper grounding should diminish most of them, as well if you use balanced connections.
So after you build your power amp you should test it by getting your volume up, with no signal, and listening with your ear close to the tweeter. AM radio is easy to identify, but other sources are not.
If you have a scope you could do the same, up to 1MHz, with more accuracy.
If everything is clean go ahead. There was a high-end amplifier made in Switzerland that used an acrylic box. But the supply was in a separate box, if I am not wrong.
Carlos |
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| getafix |
| are you going to use just one transformer for both channels? how would that look like? |
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| honsten |
heres an idea, i was in a physics lecture recently and we were disgussing magnetic and radioactive shielding and i started daydreaming.....
surely the best idea is to make the entire case out of thick lead as this will act as isolation from small vibrations as well as EMPs and alpha,gamma and betta rays! the best possible material,if a little heavy. |
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| purplepeople |
Honsten: You could call such an amp the Roach since it and it's biological cousins would be the only things to survive a detonation. In fact, with enough lead, it would poison you long before old age made your hearing bad. (heh!)
Vikash: I noticed that you used tangents on the sides but not on the front... is that just to over emphasize the pillars when viewed on the rack?
:)ensen. |
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| Nuuk |
| quote: | | surely the best idea is to make the entire case out of thick lead as this will act as isolation from small vibrations as well as EMPs and alpha,gamma and betta rays! the best possible material,if a little heavy. |
Would you make a guitar or violin out of lead? Think of a piece of hi-fi like a musical instrument and you won't go far wrong.
I once used large amounts of lead to dampen an amp case and every bit of 'life' went from the music. It was awful. :att'n: |
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| Ropie |
| plywood, plywood and more plywood |
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| Nuuk |
| quote: | | plywood, plywood and more plywood |
Well, he is an architect after all! :D |
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| Nuuk |
| Very nice Dioklejan. Am I correct in assuming that you have taken a standard case and clad it with the oak panels? |
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| Vikash |
| quote: | Originally posted by getafix
are you going to use just one transformer for both channels? how would that look like? |
Err, kinda like it's pictured?
| quote: | Originally posted by purplepeople
I noticed that you used tangents on the sides but not on the front... is that just to over emphasize the pillars when viewed on the rack?
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I'm not sure I understand, but it's probably just the lighting. This was just a draft idea to see if a transparent open design case would have any appeal (but the lack of comments makes me think I'm the only one that likes it :D) It may require one flat side to mount everything, but I would like to avoid that if possible... |
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| Ropie |
Well, if you are the only one that likes it, build it anyway ;) I quite like it but don't think the curves do it any favours.
An idea I have been thinking about may interest you: some people like to fill their cases with resin to try and isolate all their components from external vibrations. How about if you were to make a box, put your amp components in, fill it with resin and then take away the box? You would just have a block of resin with an amp inside and you could also cast those big spike feet into the corners.
Unless you build everything into a (preferably metal) box to show on this forum all you get are funny looks anyway :apathic: |
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| Nuuk |
| quote: | | How about if you were to make a box, put your amp components in, fill it with resin and then take away the box? |
That would make tweaking a bit difficult wouldn't it Ropie? :att'n:
Vikash, I like your design and if you have the materials I would say go ahead and build it (and then a matching CD player/transport).
I have often wondered if these plastic type materials attract static but my GC monoblocks don't seem to have a problem and Pedja built that nice circular GC case out of acrylic and didn't report any problems either. :smash: |
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| Ropie |
If you make sure the design is good enough and working to its full potential before you encase it there shouldn't really be a problem. Then if it breaks down you have a nice paperweight.
BTW, we are still at the current address for a couple more weeks so post away! :) |
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| Jamh |
| good design vikash. You could position the heatsinks so that block most of the internals, otherwise, it might be a dangerous amp. Another alternative for safety is to wrap the sides with perforated metal, sorta like the fi amps |
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| Bill Fitzpatrick |
| quote: | Originally posted by Nuuk
Would you make a guitar or violin out of lead? Think of a piece of hi-fi like a musical instrument and you won't go far wrong.
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Ridiculous. |
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| JazzzSpazzz |
| quote: | Originally posted by Nuuk
Would you make a guitar or violin out of lead? Think of a piece of hi-fi like a musical instrument and you won't go far wrong.
I once used large amounts of lead to dampen an amp case and every bit of 'life' went from the music. It was awful. :att'n: |
I have to disagree. The goal for a guitar & an amp (or speaker) are very different. The box for a guitar needs to resonate & this motion will color the sound and give the instrument its own sound. Once the sound of the guitar has been recorded, you really don't want to change it--just amplify it. (Unless you like tube amps :D :D :D ) The goal is to accurately reproduce the recorded signal not to change the signal.
I don't know why your lead amp failed, but it was not because the box would not vibrate!
Cheers,
Bret Morrow |
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| honsten |
| how come it has such a bad effect? is it one of those mysteries of the universe or is there a simple reason? |
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| purplepeople |
| quote: | Originally posted by Vikash
I'm not sure I understand, but it's probably just the lighting. This was just a draft idea to see if a transparent open design case would have any appeal (but the lack of comments makes me think I'm the only one that likes it :D) It may require one flat side to mount everything, but I would like to avoid that if possible... |
I like the shape. From the drawing it seems that there are no sides, just a top and bottom. Or... will you put at least a front panel so that the controls can be mounted to something? If you do, will the curve pose a problem for mounting switches or pots?
:)ensen. |
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| Vikash |
| quote: | Originally posted by Ropie
BTW, we are still at the current address for a couple more weeks so post away! :) |
Huh?
| quote: | Originally posted by Jamh
You could position the heatsinks so that block most of the internals, otherwise, it might be a dangerous amp. Another alternative for safety is to wrap the sides with perforated metal, sorta like the fi amps |
Those amps look really nice. I quite like the idea of an upright amp too, but I'll start simple ;)
| quote: | Originally posted by Bill Fitzpatrick
Ridiculous. |
Expressed tactfully as usual Bill. ;)
| quote: | Originally posted by purplepeople
I like the shape. From the drawing it seems that there are no sides, just a top and bottom. Or... will you put at least a front panel so that the controls can be mounted to something? If you do, will the curve pose a problem for mounting switches or pots?
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Yes, there is only a top and bottom. I was initially thinking about mounting terminals etc. on the top, but we'll see. I'm waiting for the pcb's and then I'll come up with a more serious design once I've got a working amp on mdf. I think I need to find a tidy layout that's ok to show through transparent material first... |
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| analog_sa |
| quote: | | how come it has such a bad effect? is it one of those mysteries of the universe or is there a simple reason? |
Nothing in audio is simple. Certainly not if you posess even minimal hearing.
What is simple is that large amounts of lead will increase the mass and lower the resonant frequency making it much more difficult to control vibrations.
Less obvious is that the increased damping of lead is often robbing music of all life. There are different (admittedly not very convincing) theories why excessive damping is bad for sound but my (and others) listening experience points it is. Whether it is applied to room acoustics or equipment construction/support there is a certain maximum damping which should not be exceeded. |
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| bishopdante |
| quote: | Originally posted by Nuuk
Would you make a guitar or violin out of lead? Think of a piece of hi-fi like a musical instrument and you won't go far wrong.
I once used large amounts of lead to dampen an amp case and every bit of 'life' went from the music. It was awful. :att'n: |
This is an interesting point. A hifi is a musical instrument, rather than scientific apparatus. I have always found that scientifically precise mics sound a bit funny (B&Ks matched pairs in particular) When recording drums, you have to mess around with the recording to put back 'body' where the recording process has lost some of the sound. You have to compress it, distort it, EQ it, you name it to get it to sound like the impression you got in the room with the drummer whacking the kit. This is not scientific, it's like art dude! A good hifi messes around with the sound but in a good way. A bad hifi (think Sony mini system with triple megabass and plastic/cardboard speaker boxes) messes around with the sound in a bad way. And after all recorded sound is an object not a sound. There is no accurate point of reference. CDs don't sound like anything unless you put em in a player. Ruark Solstice speakers don't have an especially flat frequency response, and they're not that accurate. By Reference Monitor standards they're a bit ****. But they sound huge, fat and detailed. I love it. The sound is absolutely beatiful. They are a superb musical instrument. It's the same with Tannoy Monitor Golds, by modern standards they aren't very accurate. But again they sound absolutely superb. (but both of these speakers compared to the horrid little sonys are super super accurate)
A good analogy is photography. If you look at the real world, you see something, an image limited only by the dynamic/colour range of your eyes. A photograph has much less dynamic range/colour range, so if you pick up all the detail in a scientific manner, the photo looks boring and washed out. Instead, a good photographer will underexpose and overexpose to taste in order to accentuate certain choice details, and the resultant effect is dramatic rather than scientific. A captured scientific representation is always going to be less than the real thing being captured, but art is something else. It is a new thing in its own right. Creative rather than reductive. Or is it distortion? (I love nice distortion, but spare me the comb filter)
In the photography domain the Tannoys and Ruarks are like a Hasselblad or Nikon F1. And the Sony is one of those **** automated compact cameras with plastic lenses.
This is somewhat off the thread though. Have you tried making casings out of Nougat? Nougat is very easy to nibble into shape and it sticks together beautifully if you lick it for a couple of minutes.
I would have thought that the sound is effected far more by the design of the circuits than what box you put the circuits in. It's not an acoustic device y'know. Wood/polystyrene/lead in the acoustic world correspond to Copper/Aluminium Oxide/Plastic to my imagination. And if you use plastic cabling instead of copper cables in your amp it will sound really bad. I'm not so sure that acoustically damping the case down with lead will make that much difference, but I haven't tried it myself. Could it be that the lead was sapping the current out of the cables due to an electromagnetic effect? It wouldn't be anything acoustic, cos the signal is not being transmitted in that domain. It must be an electronic effect. Or is it the fabled euphonics? Has anybody ever tried strapping an amp to a strongly vibrating table and seeing How that changes the sound? I'd love to know. |
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| Bill Fitzpatrick |
| quote: | Originally posted by bishopdante
A hifi is a musical instrument, rather than scientific apparatus. . . A good hifi messes around with the sound but in a good way.
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Ridiculous. And you photographic analogy is way off the mark too. |
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| Vikash |
| quote: | | A hifi is a musical instrument...A good hifi messes around with the sound but in a good way. |
A hifi is not a musical instrument, nor should it mess around with the sound IMO. Off course they all do, and such is the toll of recording, storing, and reproducing, but it's such colouring that we, well I at least, are trying to reduce.
| quote: | | A good analogy is photography. If you look at the real world, you see something, an image limited only by the dynamic/colour range of your eyes. A photograph has much less dynamic range/colour range, so if you pick up all the detail in a scientific manner, the photo looks boring and washed out. |
Err hmm. But we don't take those art forms then manipulate them or add colour to them after the photographer has created his/her piece. Continuing your analogy then, a photographer creating and image for others to enjoy (be it accurate, highlighted, or whatever at the skill and desire of the photographer) is analogous to the musician(s) and others involved in creating their art piece and recording it on some medium. The hifi merely allows us to view this picture, and ideally I would like no colour added please!
Art is art, I ain't arguing. But it's science that's allows us to record and then reproduce this art and the goal should be to ensure it is uncoloured as much as is currently possible. |
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| RHosch |
| quote: | Originally posted by analog_sa
What is simple is that large amounts of lead will increase the mass and lower the resonant frequency making it much more difficult to control vibrations. |
It will lower the resonant frequency, but why should that make it more difficult to control vibrations? Increased mass will lower the amplitude of forced excitations for all frequencies other than the resonant mode. If you lower the mode to a frequency below the forcing stimuli in the environment, you have effectively controlled the vibrations... exactly the opposite of what you suggest.
And the thought that damping vibration of a solid state electrical device would somehow "rob" it of musicality... well, that's ridiculous. As ridiculous as thinking the vibrations would affect the sound in the first place. |
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| Nuuk |
| quote: | | If you lower the mode to a frequency below the forcing stimuli in the environment, you have effectively controlled the vibrations... exactly the opposite of what you suggest. |
Doesn't this statement assume that the item being damped doesn't have any vibrations of its own which would mean (according to my understanding of physics) that it didn't exist? :cannotbe: |
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| eeka chu |
If it was supercooled to absolute zero then it wouldn't be creating any vibrations it's self.
Most cryogenic labs have trouble getting into the last few degrees of absolute zero.
I imagine that the amount of gas boiling off your Hi-Fi to achieve this effect would be very impressive in it's self, probably more so than the Hi-Fi!
Whether supercooling with liquid helium is a viable option for your home Hi-Fi, I'm not so sure! :xeye: :D
There is one advantage to this method and it's that you could also have a superconducting Hi-Fi. Yay! |
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| dhenryp |
| quote: | Originally posted by eeka chu
If it was supercooled to absolute zero then it wouldn't be creating any vibrations it's self.
Most cryogenic labs have trouble getting into the last few degrees of absolute zero.
I imagine that the amount of gas boiling off your Hi-Fi to achieve this effect would be very impressive in it's self, probably more so than the Hi-Fi!
Whether supercooling with liquid helium is a viable option for your home Hi-Fi, I'm not so sure! :xeye: :D
There is one advantage to this method and it's that you could also have a superconducting Hi-Fi. Yay! |
...And you could get a away with a REALLY small heatsink... |
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| RHosch |
| quote: | Originally posted by Nuuk
Doesn't this statement assume that the item being damped doesn't have any vibrations of its own which would mean (according to my understanding of physics) that it didn't exist? :cannotbe: |
Yes, everything has self-vibration on some scale, and everything resonates as well. The amplitude of that resonation is what we are concerned with. If you add mass and lower the first mode to a frequency below the majority of forcing stimuli, then any remaining resonantions will be lower in amplitude than that caused by the rather large forcing functions produced by speakers. That is assuming you can add enough mass to lower the frequency sufficiently, of course.
The question still remains however... why be concerned with the vibration of solid state electronics? |
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| Nuuk |
| quote: | | The question still remains however... why be concerned with the vibration of solid state electronics? |
So are you saying that it doesn't matter which type of case we use, which type of equipment platform etc etc? |
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| RHosch |
| quote: | Originally posted by Nuuk
So are you saying that it doesn't matter which type of case we use, which type of equipment platform etc etc? |
Yes, that's absolutely what I'm saying. You could mount some of the opamps in a circuit on a vibrating transducer, and in a controlled test you'd never hear the difference between that and a completely isolated one.
Chasing microphonics in solid state circuitry is an utter waste of time. You can show that capacitors have a theoretical microphonic effect, but again you could never establish that the effect is audible... because it isn't. |
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| eeka chu |
I agree.
Although, I think capacitors may have some degree of audiable interface with the mechanical world.
If you charge up a high voltage, high storage capacitor, the peizo electric effect makes it whistle as the charge builds up.
I would think that this effect only occurs with film type capacitors, not solid based caps.
If this effect works one way, I'm quite confident that it also works in the opposite direction - creating currents as the vibrations distort the rolled up sheets.
But like your suggesting, things need keeping in context.
I'm only saying this thinking that it may be interest to someone, not that you should mount your Hi-Fi in 12ft of styrofoam. :D :p |
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| chris ma |
One time I have built a bank of DC supply caps total 90000uf after a regulater. I actually heard a buzzing noise and investigated, and saw one of the caps vibrating violently yet no spark produced, could not hear anything obvious from the speaker. A bad solder joint with one of its leads. I guess the current was quite high 2A iq bias I think it was and kept pulling or pushing it from the solid copper rail.
Chris |
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| bishopdante |
| quote: | Originally posted by Vikash
A hifi is not a musical instrument, nor should it mess around with the sound IMO. Off course they all do, and such is the toll of recording, storing, and reproducing, but it's such colouring that we, well I at least, are trying to reduce.
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Good job! You see, what the artists need is a wider range of colours to play with! The current standard of audio is not enough man!(especially thanks to Sony and their Megabass)
Err hmm. But we don't take those art forms then manipulate them or add colour to them after the photographer has created his/her piece.
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Yes we do, It's called 4 colour litho printing. All books are printed like that and it has about half the range of colours of photographic film, and about a tenth of what the eye can pick up. It also has no detail in the pale and dark tones. When you print a photo, the reprographics guy bumps up the colour (saturation), losing objective detail, but heightening the perception of detail. This makes for a better looking photo in a book, but it will be nothing compared to an original print. I used to work in graphics y'know!
Continuing your analogy then, a photographer creating and image for others to enjoy (be it accurate, highlighted, or whatever at the skill and desire of the photographer) is analogous to the musician(s) and others involved in creating their art piece and recording it on some medium. The hifi merely allows us to view this picture, and ideally I would like no colour added please!
[/QUOTE]
Then go to a gallery, and see the original print. This is called a recording studio, which most agree is where records sound really good. Off 2" master tape. Oohyeah baby. Most do not have this privelage. |
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