Hi,
i would like to get some opinions about the use of acrylic cases for preamps (line)
I know of some high level commercial units using this material
Is it an interesting option ? why ?
Is difficult to make holes in this material ?
Personally i like the fact that is not conductive so isolation of ins and outs is automatic ... i very much like this actually.
Thanks a lot. Kind regards, gino
i would like to get some opinions about the use of acrylic cases for preamps (line)
I know of some high level commercial units using this material
Is it an interesting option ? why ?
Is difficult to make holes in this material ?
Personally i like the fact that is not conductive so isolation of ins and outs is automatic ... i very much like this actually.
Thanks a lot. Kind regards, gino
> Is difficult to make holes in this material ?
No, however you need a well sharpened drill bit. Like other plastics, it your drill bit is dull, it will heat and melt.
It still has the drawback that it is non conductive, so whatever is inside is unshielded, making it unsuitable for audio stuff, unless you live in a place without cellphones, wifi, radio, etc.
No, however you need a well sharpened drill bit. Like other plastics, it your drill bit is dull, it will heat and melt.
It still has the drawback that it is non conductive, so whatever is inside is unshielded, making it unsuitable for audio stuff, unless you live in a place without cellphones, wifi, radio, etc.
A solid case not only has the benefit of shielding your electronics from RFI but also from critical eyes.
If you are very proud of your workmanship then let the World share it with you.
If you are very proud of your workmanship then let the World share it with you.
Nice to showoff if your build is stunningly beautiful, but lack of shielding and sheer mechanical weakness kills its practical use.
You will see quite a few acrylic cases at Audio Expos and Fairs just for that reason, but not for sale to the public.
Here´s a power supply:
You will see quite a few acrylic cases at Audio Expos and Fairs just for that reason, but not for sale to the public.
Here´s a power supply:
Hi and thank you All sincerely for the very helpful advice
I know of some examples of audio equipment using this material for case
Some reasonings for this choice can be found here
DNM Design Principles, Page 3 of 5 - Materials Technology
Some inexpensive boxes for food or similar can be found in the market
It is not a matter of look ... but i think that maybe "stray current" are involved ?
the plastic case of course will avoid any possible stray current
Thanks a lot again, gino
I know of some examples of audio equipment using this material for case
Some reasonings for this choice can be found here
DNM Design Principles, Page 3 of 5 - Materials Technology
Some inexpensive boxes for food or similar can be found in the market
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It is not a matter of look ... but i think that maybe "stray current" are involved ?
the plastic case of course will avoid any possible stray current
Thanks a lot again, gino
One could of course spray the interior with conductive paint and ground it... The box would keep its sharp angles and probably look very cool...
Regards
Regards
Unless you buy from a distributor, or a retailer who truly knows his stock, you may find that any clear or transparent plastic sheet is called "acrylic". Some of it is; some is actually polycarbonate.
Both acrylic ("Plexiglass", "Perspex", et al) and polycarbonate ("Lexan" et al) are fairly easy to machine with hobbyist tools - though the two materials behave somewhat differently.
- As with nearly all things related to DIY, practice and experiment before performing the operation on your real project.
- I use the same carbide-tipped saw blades, drill bits, and router bits I use for woodworking.
- Acrylic in particular needs sharp, clean, cutting edges to avoid conchoidal chipping along the cut.
- These are thermoplastics. The heat generated at the tool's cutting edge will soften the plastic and cause the chips to stick to the tool, or re-attach to the plastic material. Contrary to your intuition and experience with other materials, increasing the feed rate - perhaps even to a speed that feels uncomfortable to you - can reduce this problem.
- Plastics distributors and some of the larger woodworking retailers offer bits and blades which are supposedly optimized for plastics. (I think the major factor is the angles of the cutting edges.) They may offer better performance, but I have never tried them - nor felt a real need to try them.
- Router bits designed to remove the chips from a cut are worth the investment if you often use your router on plastic. Select "spiral up-cut" or "spiral down-cut" styles depending on the type of cut and how you are using your router (hand-held, table-mounted, horizontal spindle, etc).
- Common steel files work on plastics but may clog in just a few strokes. Files specifically designed for plastic (relatively coarse, with wider spacing between the teeth) work much better than common mill- or bastard-cut files.
- Acrylic and polycarbonate can be drilled and tapped for machine screws. The threads hold surprisingly well if you use U.S. size #6 or larger diameters, and the "coarse" thread pitch series (i.e., 6-32, 8-32, 10-24, 1/4-20, etc). Unfortunately, I believe the standard metric thread pitches are significantly finer than these, so may not be practical.
- Acrylic is easy to glue. (The professionals call it "solvent welding".) Make your own glue by getting some pure acetone from the hardware or beauty-supply store (beware of nail polish remover that claims to be "as good as acetone" - it is NOT what you want!). Put about 15 - 25 mL (a tablespoon or two) into a small glass jar, then add small chips or shavings of acrylic (from the scrap pile), and stir or shake until the acrylic dissolves. Adjust the thickness (viscosity) of your glue by varying the ratio of solvent to plastic. Practice a few joints to get a feel for the working properties, set-up time, etc of your glue.
(For gluing polycarbonate you can probably find a suitable commercial product on the shelf at a local hardware or home-center store.)
The angle of the drill bit is important and what works well with metals doesn't always work well with plastics.
You want a bit that "scrapes " it's way thru the plastic. What will happen is a regular bit will tend to pull into the material and crack. Especially at the exit of the acrylic.
Thicker materials often don't show up any differences as much as thin plastics that break more easily.
Regards
David
You want a bit that "scrapes " it's way thru the plastic. What will happen is a regular bit will tend to pull into the material and crack. Especially at the exit of the acrylic.
Thicker materials often don't show up any differences as much as thin plastics that break more easily.
Regards
David
I just looked, and there are a number of turntables based on clear plastic, like Clearaudio. But I seem to recall a clear turntable from 30-40 years ago.
Acrylic is one not forgiving material, and about cutting it and drilling it and even after finishing the project, cleaning and keeping it free of fingerprints and scratches it would be impossible.
I would suggest a better solution, one six centimeter high aluminum chassis (oven dish pie) which would have bolted on PCB and parts, and as exterior cover a cube made of true glass.
The glass cube would be exclusively a top cover, no holes over it.
I would suggest a better solution, one six centimeter high aluminum chassis (oven dish pie) which would have bolted on PCB and parts, and as exterior cover a cube made of true glass.
The glass cube would be exclusively a top cover, no holes over it.
Stress fractures can be an issue...but have done an electron microscope PSU in a polycarbonate case.
Interesting view from DNM design, of course there is a wealth of sensitive equipment put in metal cases, if for no other reason shielding😕
Interesting view from DNM design, of course there is a wealth of sensitive equipment put in metal cases, if for no other reason shielding😕
Hi and really sorry to everyone for my belated reply.
I had some family issues.
Thanks a lot for all your valuable advice.
I have come to a conclusion.
The only "piece" that could create problem is the power transformer with its magnetic field
I truly believe that shielding or removing it from the box containing the circuitry could be beneficial
Acrilic is just a pain to work with and no needed at all if the transformer is in another metallic box.
I notice that some preamps actually have the power supply separated from the amplifying circuits.
It makes me sense. I have also seen preamps with the mains transformers shielded.
I think the overall effect should be similar.
Thanks a lot to everyone
Regards, gino
I had some family issues.
Thanks a lot for all your valuable advice.
I have come to a conclusion.
The only "piece" that could create problem is the power transformer with its magnetic field
I truly believe that shielding or removing it from the box containing the circuitry could be beneficial
Acrilic is just a pain to work with and no needed at all if the transformer is in another metallic box.
I notice that some preamps actually have the power supply separated from the amplifying circuits.
It makes me sense. I have also seen preamps with the mains transformers shielded.
I think the overall effect should be similar.
Thanks a lot to everyone
Regards, gino
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