Wooden Enclosures Prt 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th March 2005, 06:58 PM   #1
pjpoes is offline pjpoes  United States
diyAudio Member
 
Join Date: Jan 2005
Location: New York
Send a message via AIM to pjpoes
Lightbulb Wooden Enclosures Prt 2

Ok so the original discussion in this became sidetracked and heated, so I stopped talking in it. I wanted to bring the topic back up though, to express the thinking I had, as far as possible improvements in sound. First I want to say that objectivly, I am still not convinced it will do anything. Subjectivly I feel there is some sensible thought in how it might, and that I want to try it to hear for myself. I also see that there have been attempts to prove the improvements objectivly, and some of the science is sound, the biggest problem becoming, does that actually effect sound.

The thoughts put into this by most designers is first and formost, and issue of Eddy currents. THe main reason, atleast from my research on the subject(reading), that aluminum is used for most highend enclosures is that its a non-magnetic metal and so will not have an effect on the electrical transmission throughout the signal. I think we can all agree that when an electrical signal is tranmitted down the line, a magnetic field is created. I think we can also agree that magnetic fields are easily influenced my magnetic material. Another intresting thing to consider is that a magnet will also influence the flow of water, try it with your sink sometime. THat last bit, to me atleast, suggests that even non electrical flows of electrons are still influencable, but Im not sure the relevance to electrical signals. All that being true, and given that the level of the signal, especially at the low levels of sources and preamps, probably doesnt take much to influence them through the interaction of magnetic material. I imagine that this effect is measurable, according to companies like DNM, it very much so is.

Now you have it atleast somewhat settled that magnetic metals can interact with the electrical signal, thus changing it, and degrading it. Atleast based on these idea's of eddy currents. It also has to be admitted that, "if its so good why doesnt everyone do it" is somewhat true, when money is not an issue. However some seem to say that even non-magnetic metals like brass or aluminum are infact magnetic, when an electrical signal is passed over them. I have tested magnetic fields of simple copper coils, and they do exist, so I have to admit that this must be true. However, they are weaker than when an iron core is introduced, and current is being run directly through the wire, where as in an enclosure, it has to be induced from the flow of electroncs near it, so I imagine its considerably lower. None the less, now it can be seen how any sort of metal enclosure could potentially become magnetic, and going with the eddy currents premise, degrade the signal.

SO then you are left trying to use something that is non-magnetic always so as not to introduce stray eddy currents, and corrupt the signal. Materials for that are things like acyrlic, plastic, ceramic, aluminum oxide, and wood. I am sure more exist, its what i could think of, its just a short list to make my point. DNM feels that Acrylic is best, I can understand that, its easily formable, readily machinable, inexpensive, and non-magnetic. It also has pretty good internal dampening properties, but not great. Wood is far more expensive(atleast quality hardwoods), not as machinable, and not as strong(not as flexible). Many companies have however chosen wooden enclosures, though most still use a more solid metal base or top plate, as its more practical. I think that the DNM idea of isolating the cuircit from metal as much as possible is probably crucial, internal consistency for the theory anyway, so all wood would be needed.

I also did a great deal of research, of the reading type, no this topic. Obviously very little experimentation in controlled lab enviroments have been done on this for the purposes of audio. However, you can guess that if its true in general, its probably true for audio, so I have done the same thing in extrapolating information from other area,s. I read articles by scientists and proffessors dealing with oscillations of resonances and the effect on transformer wires, electrical transmission, etc. I also read how physical vibrations can effect the transmission of electrons, changing the oscillation and introducing error. The last two idea's started with studies used for the transmission of AC electricity to houses, and the frequency shifting as a result of movement in the wire, and causing issues with certian companies that rely on a steady 60hz. Another study dealt with small vibrations and oscillations in adjacent cuircits effecting the tranmission of oscillated signals for computer products. It was a phenomina found in some kinda of grain counting computer used in farming that was having a great deal of error for unknown reasons. The solution was to isolate the cuircits from external vibrations, along with moving small oscillators, used in different cuircits, away from each other. I figure, all of this is suggesting that a well dampened enclosure is important as well. Wood seems to offer decent dampening, though maybe not great. I also think that, based on Eddy currents and these studies, a metal enclosure could be excited by the current in the amplifier cuircit, causing it to "sing" along with the cuircit, but because of the distance and differences in the transmission, it wouldnt be in the same time, and so would cause non-identical echoes. Its a guess, I have no proof of this, Im simply suggesting a possible issue. I suppose this would be the idea of energy storage in enclosure materials. I think that wood has a more musical storage of energy, its why we like it for use in isntruments, it has a great resonation to it and musical dissipation of energy.

My final thought on this is that, even if all of the above is true, is the effects large enough to be audible? Is human hearing more sensitive than we can measure for, is there more to it than measurements? I dont know? I have no idea if its audible, but I know that my hearing is accute and sensitive, I hear things others dont. I'm a Pita when it comes to playing in a band as I can hear when a string is out of tune, better than those cheap handheld tuners can, and will often feel a song doesnt sound right if someone is even remotely out of tune. I use a 400 dollar guitar tuner because I am that anul, and its the only way I can get a guitar intune enough that I feel it sounds right played in unison with other instruments, or with certain chord progressions. It leads me to believe that differences in hearing exist, and that its possible that I and others can hear things as silly and suttle as this.

I also want to address the issue of venting, heat dissipation, and strength. I do not even attempt to state that wood is as strong as metal, but I think that a strong enough enclosure can be made out of wood. If you make a box with a boocher block maple base and front plate, along with thick rear and top, I think it will be strong enough. If you then vent the top and bottom in a correcnt manner, I think that structural rigity can be mantained without creating a box that does not allow airflow around the cuircit board. Obviously an aluminum heatsink is still needed for cooling of the amplifier, and so would be done. I also plan to try this aluminum oxide spacer idea for the heatsinked parts.
  Reply With Quote
Old 8th March 2005, 08:02 PM   #2
diyAudio Member
 
BrianDonegan's Avatar
 
Join Date: Dec 2004
Location: TPA HQ
Hi pjpoes-

First, sorry for throwing your last post into the crapper. Didn't mean to.

So, I won't do it again. I do want to make a few comments about your post, just for clearification.

Any moving current creates a magnetic field, whether the current is flowing through magnetic or non-magnetic metals, or even the air (lightning creates a magnetic field). you can use the right-hand rule to figure it our. Hold you right hand out, curling your fingers, with your thumb extended. Current flowing in the direction of your thumb creates a field in the direction of your fingers. Conversely, a magnetic field moving in the direction of your fingers will create a current flow in the direction of your thumb. In three dimentions, it quickly gets more complicated.

The difference between magnetic and non-magnetic metals is tat magnetic metals can develop their own magnetic field (natural magnets) when their molecules are aligned properly. Both types of metal will create a magnetic field if current is passed through them.

Wood is an insulator (when dry) and will therefore not conduct electricity very well, and therefore will not generate a field. However, it will also not shield from external magnetic fields. Remember that they are all around us. Technicaly, you are creating magnetic fields as electrocs flow through your nerves, and as you walk arounf a room. You can hear this by moving around near a radio antenna. So, though a metal enclosure may create be affected by eddy currents, it can also shield your amplifer from them.

Magnetic fields can be used creatively to cancel one another out. Think of a bucking magnet used to shield speaker drivers for use near a TV (incidently one of the biggest EMI emitters in most homes). A small magnet is glued to the back of the main speaker magnet. The result is a cancellation of the magnetic field eminating from the driver's motor structure. This does have some effect of the field inside the driver, but it is considered worth while if the goal is placement near a TV, which uses very powerful electrically induced magnetic fields to aim beams of electrons at the back of the CRT screen.

I think it all comes down to magnetude (sic) of the fields in question. It's a lot like gravity. Any mass has a "gravitational field." I do, but it's not enough for my coffee cup to slide over to me (man I wish it would). My field is trumped by the earths field, and the resulting friction of the cup to desk interface. You reach a point when something becomes "practically insignificant." Not the same as non-existent, just, in the grand scheme of things, a minor player.

I think you need to just build some nice wood boxes. try them out. If you amp sounds good in them, you're a happy man. If you pick up some EMI/RFI, add a little shielding to see if it helps. I think wood amp cases look best.

Interesting about the powerlines. I would think the changes would occur from swinging a couple wires with massive amounts of current (and therefore magnetic fields) near each other, and the resulting currents induced in the others. But that's just my guess. Really don't know, though I do know that would be one factor. Wonder if it's also related to a subtle dopler effect.
__________________
Twisted Pear Audio
  Reply With Quote
Old 8th March 2005, 09:33 PM   #3
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
I don't mean this to sound negative, but what is the point of the first two posts? There is some rambling about trying to present some theories as to why wood might sound better. There is also a mention of how using maple properly would make the enclosure strong "enough" and have adequate ventilation (it would likely shock the people who have used wood for years to know that their enclosures were not strong enough and had inadequate ventilation).

I think you should tell people what you are hoping to achieve in this thread. People sharing results of their wooden enclosures? A discussion of various construction techniques and designs?

I like wood for enclosures. There's my $0.02.
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 9th March 2005, 02:54 AM   #4
pjpoes is offline pjpoes  United States
diyAudio Member
 
Join Date: Jan 2005
Location: New York
Send a message via AIM to pjpoes
you may not have read the first enclosure thread. It started with wondering if there was any merit in this idea of mounting a cuircit to a "tone" wood to see if it could effect the sound. Part of why I wanted to was that I love the look of wood, and thought mounting an amp to one would look nice, and if it effected the sound. There of course is that over priced Shellac that they sell that "Improves" sound. Im skeptical of that, but I bought some Violin finish, well French polish shellac stuff. I figure its probably pretty similar, its an organic resin based finish using all organic based products. I have a ton of tone woods around, including rosewood and maple, to use for this. It seemed like, though a little witchcraftish, there is some sensibility to dampening a board with wood like that, and of course making the whole enclosure out of wood, to give it a propper look.

The reason for the nature of this thread was that, others seemed appalled at the idea that Wood could even be considered as the equal of a metal enclosure, let alone better. Responses like, Steel is the best for an enclosure, but its too heavy, so they dont use it, was said. I dont agree with that, so I posted why here, along with some "evidence" as to why I disagree. I am on a wood kick right now, I have been putting everything in my specially finished wood, and if nothing else, I love the look. But I didnt want this thread to simply be about the asthetic issues of using wood, I also wanted to discuss possible technical advantages, and what others thought about my conclusions. The reason for my Elemtary tone in the first thread was that some responses to my original thoughts seemed so fundamentally off based, atleast with my premise, that I needed to explain the process by which I came to my conclusions. I already "Knew" what I posted above, but of course, you cant really make a good point based on something you remember from a class, so I re-researched it. I also learned a great deal of new things. For instance, I wondered if signals traveling through wire could possibyl be effected by vibrations of sorts. I did not find a conclusive answer on that, though I did find some evidence, in other studies, that suggested that vibrations could indeed effect a signal. This leads me to believe that dampening a cuircit board is a good idea.
  Reply With Quote
Old 9th March 2005, 06:25 AM   #5
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally posted by pjpoes
This leads me to believe that dampening a circuit board is a good idea.
Small wonder that there already have been people advocating that, and commercially implemented.
__________________
The buck stops Here
  Reply With Quote
Old 9th March 2005, 03:11 PM   #6
diyAudio Member
 
BrianDonegan's Avatar
 
Join Date: Dec 2004
Location: TPA HQ
So, aside from the technical issues...

For those thinking about building wood cases, and looking for sound building methods (joinery), I highly recommend the book "Tage Frid Teached Woodworking." It is a three volume set by Taunton Press (available through Amazon and many others). The first two volumes are available as a single book, which I recommend.

It starts off with a fairly thorough discussion of wood, grain, and principles. The joinery book covers how to make just about every joint you can imaging, with step by step technical drawings. If you don't know who Tage Frid is, and would like to, click here.
__________________
Twisted Pear Audio
  Reply With Quote
Old 9th March 2005, 03:46 PM   #7
pjpoes is offline pjpoes  United States
diyAudio Member
 
Join Date: Jan 2005
Location: New York
Send a message via AIM to pjpoes
Quote:
Originally posted by jacco vermeulen


Small wonder that there already have been people advocating that, and commercially implemented.

Yeah I know, but I dont want to state that dampening a board is a good idea because Krell or Conrad Johnson says it is, and I'd rather not believe it myself until I hear it and see some technical evidence as to how it might. I havent yet heard my own version, but I have found some evidence to suggest that what they say is infact true.

That book suggestion was a good idea, as much as I love wood, Im not that great at working with it. I'm sure there are others like me here.
  Reply With Quote
Old 9th March 2005, 04:31 PM   #8
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Like me.
I did quite a lot of woodworking, but never took the time to learn the basics. Good suggestion, B.
__________________
The buck stops Here
  Reply With Quote
Old 25th March 2005, 02:48 PM   #9
diyAudio Member
 
Join Date: Apr 2003
Location: NY
I was following your exposition until I got to your use of the $ 400 guitar tuner. If you rely this much on a guitar tuner to get your strings in tune, you should probably put your "anal" ambitions into developing a more differentiated musical hearing first, before you become concerned about interference caused by eddy currents. The best professional piano tuners use their ears almost exclusively, and this will be the kind of sophistication in hearing that you will need to decide whether your concerns have any impact on the sonic signatures of sound reproduction.

Cheers

__________________
RB
  Reply With Quote
Old 25th March 2005, 03:09 PM   #10
diyAudio Member
 
BrianDonegan's Avatar
 
Join Date: Dec 2004
Location: TPA HQ
Funny, I was just thinking of posting to this thread.

I am building an enclosure out of walnut. For shielding, I found the Home Depot sells 20' rolls of 8" copper flashing (3oz copper with a thin polymer backing. I am going to adhere this to the inside surfaces of the walnut and solder the corners. should be pretty sharp looking inside and out. This amp will also be water cooled, with polished copper heatspreaders and tubing. (Aleph 30).
__________________
Twisted Pear Audio
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Custom Wooden Audio Enclosures zeroed4x Vendor's Bazaar 0 24th June 2009 10:50 PM
Wooden Enclosures and Consoles Phatriff Parts 5 21st September 2007 09:36 AM


New To Site? Need Help?

All times are GMT. The time now is 02:37 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2