AudioCircle
Industry Circles => GR Research => Topic started by: russellberg on 12 May 2020, 04:38 am
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I'm an experienced woodworker but a rank novice when it comes to electronics. Im looking forward to learning a lot and have started with Danny's Servo Sub kit.
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Welcome to AudioCircle!
Starting with a kit is a wise choice. You get a good boost of confidence, plus you can listen to it while you read up on speaker design.
There's a lot to learn, but it's very fun. Please share your projects with us in the Enclosures Circle, Thanks!
Rich
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Same here. The cabinets will be easy, but I don't know an amp from an ohm and I haven't soldered anything since building slot cars as a kid 50 years ago.
Welcome aboard.
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If you're interested; PM me and I send you my CAD drawings, parts list, etc... for the speaker shown below. I just built a pair for a friend who prefers their sound over his $28K Legacy Whispers. They require bi-amping with a digital crossover, and it's not an easy build-- but if you're up for it, they're freaking awesome.
Here's a video too: https://youtu.be/9HTKh58wYlo
(https://www.audiocircle.com/image.php?id=208791)
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Welcome :thumb:
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Welcome to Audio Circle. :D
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That looks incredible! What sort of speakers is the flat panel filled with? Is the bottom driver an open baffle design? I haven't watched your video yet, but I definitely will.
-Russell
If you're interested; PM me and I send you my CAD drawings, parts list, etc... for the speaker shown below. I just built a pair for a friend who prefers their sound over his $28K Legacy Whispers. They require bi-amping with a digital crossover, and it's not an easy build-- but if you're up for it, they're freaking awesome.
Here's a video too: https://youtu.be/9HTKh58wYlo
(https://www.audiocircle.com/image.php?id=208791)
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That's what I thought, so I have started with this one, https://www.youtube.com/watch?v=BvKF38sXV60 I am building them out of solid butternut with purple heart and maple accents.
Welcome to AudioCircle!
Starting with a kit is a wise choice. You get a good boost of confidence, plus you can listen to it while you read up on speaker design.
There's a lot to learn, but it's very fun. Please share your projects with us in the Enclosures Circle, Thanks!
Rich
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That looks incredible! What sort of speakers is the flat panel filled with? Is the bottom driver an open baffle design? I haven't watched your video yet, but I definitely will.
-Russell
This is a hybrid electrostatic speaker. The flat panel ESL is a stepped-frequency/stepped phased array of copper wires driving the diaphragm from the center outward to project a curved wave front. A Peerless SLS 12 woofer mounted on an open baffle (modified H-baffle) provides bass below 225Hz via a digital crossover. I've been building ESLs for 12 years and this one is the finest speaker I've ever heard.
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I enjoyed the build videos. Have you ever measured the off axis response? I have experienced the Sanders speakers; great along one line. At shows the listening chairs are three to five from front to back. How many hours are required for you to build a pair?
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I enjoyed the build videos. Have you ever measured the off axis response? I have experienced the Sanders speakers; great along one line. At shows the listening chairs are three to five from front to back. How many hours are required for you to build a pair?
I've never measured the off axis response; although the dispersion is obviously much wider than an unsegmented flat panel like Sanders uses (I've built quite a few unsegmented flat panels so I have a good reference point). And these were not my first segmented panels BTW. In this new speaker I've actually dialed back the dispersion a bit, to regain some of the magical imaging that an unsegmented flat panel provides at its focus.
I love the imaging from unsegmented panels at their focus, but the head-in-a-vise effect comes with it. My new speakers are a pretty good compromise-- giving nice imaging without the head-in-a-vise effect.
Figure about $1k for materials and 125 hours to build the wire stretching/stator jig and speakers.
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I'm an experienced woodworker but a rank novice when it comes to electronics. Im looking forward to learning a lot and have started with Danny's Servo Sub kit.
Hi, Starting Block is really for people to introduce themselves. This question/thread is best posted in GR Reseach Circle, so I'll move it there for you now.
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Welcome!
That's what I thought, so I have started with this one, https://www.youtube.com/watch?v=BvKF38sXV60 I am building them out of solid butternut with purple heart and maple accents.
I would caution you not to use solid wood for speakers. It is not usually done. Solid wood moves too much and resonates too much. Most speakers are build using MDF and then veneered. It is more inert than solid wood.
Cheers.
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I would caution you not to use solid wood for speakers. It is not usually done. Solid wood moves too much and resonates too much. Most speakers are build using MDF and then veneered. It is more inert than solid wood.
Some people believe that quality Baltic Birch plywood is better than MDF. Has a more pleasant sound. I use it for that reason plus I just don't allow MDF into my workshop. Too many bad issues with it.
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Yeah Lou at Daedalus here on AC has been building speakers with solid wood for years and gets some of the highest praise for their sound.
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Some people believe that quality Baltic Birch plywood is better than MDF. Has a more pleasant sound. I use it for that reason plus I just don't allow MDF into my workshop. Too many bad issues with it.
From a sonic standpoint, most any contribution from the box itself is an undesirable wild card. I'm curious what "bad issues" you attribute to MDF?
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The box material is just another engineering choice. Wood, ply or MDF can all be made to work, they each have strengths and weakness. Carbon fiber and steel can also work on speakers and have advantages and drawbacks. If you were commercial mfg you would use MDF for the low cost and stability of raw MDF stock in your warehouse. If you are novice woodworker you don't have planer, edger, enough clamps or glue/fastener knowledge to use real wood safely. BB is a good choice, but it is very resonant, with high Q, so bracing and damping strategies become critical at midrange freqs with BB. MDF has low Q resonance, but a wide resonant bandwidth that can destroy midrange tone quality, but simple bracing or damping can easily tame that. BB usually makes a brighter sound that people tend to like as long as enough bracing to keep it from ringing. For natural wood, spruce and plain old white pine 1x shelving wood from homedepot can sound incredibly good.
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I would caution you not to use solid wood for speakers. It is not usually done. Solid wood moves too much and resonates too much.
Solid wood is usually only used by experienced woodworkers. Lou has figured out how but for most manufacturers solid wood is too risky. Pine and alder change dimensions as humidity changes with the seasons, about 3/32" per foot. Even seasoned hardwood has problems, when people move from Wisconsin to AZ the tops and side panels of their antique furniture crack and chairs loosen up because wood looses moisture in the single digit humidity. Solid wood speakers would do the same thing, manufacturers that sell speakers worldwide discover that everywhere has a different climate than where they were made.
As long as wood speakers stay where they are made the dimensional changes will not be catastrophic. You can even break the rules. The front baffle on my speakers is 1-3/4" thick solid mesquite because I know the wood was bone dry and mesquite doesn't move very much if at all with humidity changes. The front baffle is non-resonant, self damping and extremely stiff resulting in a tight well focused sound stage.
(http://www.wghwoodworking.com/salk/cutouts_closeup.jpg)
More photos: https://www.audiocircle.com/index.php?topic=100672.msg1015847#msg1015847 (https://www.audiocircle.com/index.php?topic=100672.msg1015847#msg1015847)
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I'm curious what "bad issues" you attribute to MDF?
The worst is the fine dust that it creates, which is partially wood fibers and partially glue. I don't like breathing it or having to clean it up all over the shop. It spreads much worse than sawdust.
Then there is problem of rapidly wearing down cutting tools like table saw blades and router bits.
MDF is also very poor at holding screw treads. Many people who use it resort to inserts for attaching drivers just to be sure of a tight attachment. Not usually a problem with real wood.
And then there is the issue of finishing. It's fine if you want to paint it, but otherwise it requires veneering, which is a lot of work. BB can be found in a variety of wood types and finished like any other wood project. There is an issue, however, with the edges that show all the layers. That can be addressed by miter corners if you are willing to give up rounded over baffle edges. Or better yet use a solid wood baffle and use BB plywood for the rest of the box. Then there will be no edges visible.
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As I recall a few folks here have posted on using superglue in predrilled holes. Might check with Peer J.
And i could have had a beverage or 2 and I am still all wrong.
Alan
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The worst is the fine dust that it creates, which is partially wood fibers and partially glue. I don't like breathing it or having to clean it up all over the shop. It spreads much worse than sawdust.
Then there is problem of rapidly wearing down cutting tools like table saw blades and router bits.
MDF is also very poor at holding screw treads. Many people who use it resort to inserts for attaching drivers just to be sure of a tight attachment. Not usually a problem with real wood.
And then there is the issue of finishing. It's fine if you want to paint it, but otherwise it requires veneering, which is a lot of work.
All valid. I hate the stuff.
BB can be found in a variety of wood types and finished like any other wood project. There is an issue, however, with the edges that show all the layers. That can be addressed by miter corners if you are willing to give up rounded over baffle edges. Or better yet use a solid wood baffle and use BB plywood for the rest of the box. Then there will be no edges visible.
Another possibility is to simply glue a strip of hardwood to the edge of the plywood. A 3/4 x 3/4 piece of hardwood could be glued to the ply edge then another piece of ply attached to that at 90° to form a corner. An advantage of that is you could use a roundover bit to smooth out the look of the edge without exposing any plies.
https://img.canuckaudiomart.com/uploads/large/427079-1668c014-one_canton_karat_300_speaker.jpg
A cool way to join two plywood edges at 90° is a bird mouth joint. It looks a bit complicated, but it's really just 45° cuts on a table saw.
http://images.meredith.com/wood/images/2006/01/p_birdsmouth3.jpg
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MDF is also carcinogenic due emission of formaldehyde vapors for 5 years so it is resistant to insects.
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MDF is also carcinogenic due emission of formaldehyde vapors for 5 years so it is resistant to insects.
Despite continually banging that drum, FRM, it's just not true of MDF manufactured in North America and hasn't been for a good long time. The insect resistance you infer is simply nonsense for anything used in the furniture and cabinetry industry and sourced in USA or Canada. Perhaps an insecticide is used in siding products, but it wouldn't be urea formaldehyde. I don't know about the rest of the world.
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it's just not true of MDF manufactured in North America
Do you could prove it?
What they use ?
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it's just not true of MDF manufactured in North America
Do you could prove it?
What they use ?
Yes, I can. The only non-NAUF products being sold now come from outside USA and Canada.
https://www.rugbyabp.com/resources/green-products/nauf-product-information
http://www.integratedwoodcomponents.com/NAUF-Plywood-Manufacturers/tabid/1989/Default.aspx
https://www.snwwood.com/Lumber-Plywood/FSC-Plywood
http://www.socomi.com/build_green.shtml
https://www.westfraser.com/products/mdf/environmental-specifications
Shall I gather more?
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Gracias I will read tommorrow.
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Yes, I can. The only non-NAUF products being sold now come from outside USA and Canada.
https://www.rugbyabp.com/resources/green-products/nauf-product-information
http://www.integratedwoodcomponents.com/NAUF-Plywood-Manufacturers/tabid/1989/Default.aspx
https://www.snwwood.com/Lumber-Plywood/FSC-Plywood
http://www.socomi.com/build_green.shtml
https://www.westfraser.com/products/mdf/environmental-specifications
Shall I gather more?
NAUF stands for No Added Urea Formaldehyde, but there is still some amount of formaldehyde in MDF. Although with fairly recent legislation it is now required to be much lower than it was in the past.
It is also possible that there are other kinds of formaldehyde in MDF, such as phenol or melamine formaldehyde, that are not covered by the NAUF standard. It only apples to the Urea type.
The standard is mainly intended for consumer protection against things such as pre-manufactured furniture and cabinets. What is not clear is how much formaldehyde is released when cutting or routing the MDF material. I'm not saying that this is necessarily a problem, I just don't know if it has been addressed by the standards or not.
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NAUF stands for No Added Urea Formaldehyde, but there is still some amount of formaldehyde in MDF. Although with fairly recent legislation it is now required to be much lower than it was in the past.
It is also possible that there are other kinds of formaldehyde in MDF, such as phenol or melamine formaldehyde, that are not covered by the NAUF standard. It only apples to the Urea type.
The standard is mainly intended for consumer protection against things such as pre-manufactured furniture and cabinets. What is not clear is how much formaldehyde is released when cutting or routing the MDF material. I'm not saying that this is necessarily a problem, I just don't know if it has been addressed by the standards or not.
I should point out that the NAUF standard also applies to other manufactured panels including plywood and, I think, OSB. MDF likely has greater glue content than plywood, so there's that aspect. For those wondering what UF actually is, this lifted from Wikipedia:
Urea-formaldehyde (UF), also known as urea-methanal, so named for its common synthesis pathway and overall structure,[1] is a non-transparent thermosetting resin or polymer. It is produced from urea and formaldehyde. These resins are used in adhesives, finishes, particle board, medium-density fibreboard (MDF), and molded objects.
UF and related amino resins are a class of thermosetting resins of which urea-formaldehyde resins make up 80% produced globally. Examples of amino resins use include in automobile tires to improve the bonding of rubber to tire cord, in paper for improving tear strength, in molding electrical devices, jar caps, etc.
FWIW, I was working in the RV business before NAUF was common and we would sometimes get new units in that were simply stifling to walk into after being closed up during shipping, and I think I'm pretty tolerant of such. I do see this as movement in a good direction, but if it's a concern to you, know that MDF is not the only source.
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The dust from many exotic hardwoods can also be toxic. That's why good dust collection and the use of N95 masks is important no matter what type of material you are working with. Every type of material has strengths and weaknesses for any given application and every woodworker has personal preferences. Whatever you choose to work with, be safe doing it.
Mike
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...FWIW, I was working in the RV business before NAUF was common and we would sometimes get new units in that were simply stifling to walk into after being closed up during shipping, and I think I'm pretty tolerant of such. I do see this as movement in a good direction, but if it's a concern to you, know that MDF is not the only source.
It's not really a concern. This discussion was about MDF vs plywood for speaker cabinets and I think that the problems with MDF make it much less desirable to use. There are only two reasons to ever use MDF.
One is that it is less expensive than plywood. And that is obviously important to a speaker manufacturer who is trying to maximize profits. But for a DIYer the cost difference is trivial compared to the total cost of drivers, crossover components, etc.
The other reason is if you think it sounds better than plywood. And like most other subjective items discussed here opinions vary.
Perhaps the best box is really no box at all.
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This has got me curious. I've seen some custom speaker builds onlinr made with inner walls of MDF, and outer walls of solid wood or plywood, (or even metal) while using some sort of rubber/tar adhesive between them to help reduce cabinet resonance. (Before any norez is added)
Does having layers of different densities & resonant frequencies also help with reducing resonance, or is it more about mass and thickness?
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It's not really a concern. This discussion was about MDF vs plywood for speaker cabinets and I think that the problems with MDF make it much less desirable to use. There are only two reasons to ever use MDF.
One is that it is less expensive than plywood. And that is obviously important to a speaker manufacturer who is trying to maximize profits. But for a DIYer the cost difference is trivial compared to the total cost of drivers, crossover components, etc.
The other reason is if you think it sounds better than plywood. And like most other subjective items discussed here opinions vary.
Perhaps the best box is really no box at all.
I find MDF to be easier than BB ply to cut profiles. BB has a tendency to blow out. Also, around here, BB is three times as expensive as MDF. True, if you are only building one pair for yourself the actual difference between a 4x8 sheet of MDF and a 5x5 sheet of BB ply is only $40. Another difference is you can get the MDF broken down into smaller pieces at the store while you can only get the BB ply as a full sheet. So a person's ability to get a full sheet home and broke down could also factor into the decision.
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This has got me curious. I've seen some custom speaker builds onlinr made with inner walls of MDF, and outer walls of solid wood or plywood, (or even metal) while using some sort of rubber/tar adhesive between them to help reduce cabinet resonance. (Before any norez is added)
Does having layers of different densities & resonant frequencies also help with reducing resonance, or is it more about mass and thickness?
This technique is called constrained layer damping and has it's adherents. I haven't studied the concept well enough to know if there are real advantages or not.
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For constrained layer damping the material between layers has to be a visoelastomer, not something like rubber. Tar is an example.
It has both liquid and solid properties.
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For constrained layer damping the material between layers has to be a visoelastomer, not something like rubber. Tar is an example.
It has both liquid and solid properties.
I didn't know that...thanks Rich. I assumed it just had to be flexible, didn't know there were specific properties involved. I wouldn't have distinguished between the two examples. Forever curious it seems, I had to do some Googling. For those interested, here's a link to what Wikipedia has to say:
https://en.wikipedia.org/wiki/Elastomer
About viscoelasticity specifically:
https://en.wikipedia.org/wiki/Viscoelasticity
I suppose the whole concept of constrained layer damping is interesting to me.
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For constrained layer damping the material between layers has to be a visoelastomer, not something like rubber. Tar is an example.
It has both liquid and solid properties.
Yeah! That's it! It's been a while since I watched those videos. (Maybe a year ago beI just remembered it was some kind of elastic material that looked kinda like tar when applied.
Definitely something ill have to dig into some more!
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Here's an interesting article from Troels Gravesen:
http://www.troelsgravesen.dk/cabinet-damping.htm (http://www.troelsgravesen.dk/cabinet-damping.htm)
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Some people believe that quality Baltic Birch plywood is better than MDF. Has a more pleasant sound. I use it for that reason plus I just don't allow MDF into my workshop. Too many bad issues with it.
+1
Except for being cheap, MDF is not that good a speaker building material.
Speakers can, and have been built from solid, but you do need to know what you are doing to keep them from cracking.
I have some here in Yew and in Douglas Fir (a pine, these built from a 70-year old floor) and we have played with Western Red Cedar (a good build material except for the soft surface that easily dings) and others.
All. built by a skilled woodworker who knows what he is doing.
Fir:
(https://p10hifi.net/FAL/images/MK70wT-fir-wWoofT-comp.jpg)
Walnut:
(https://p10hifi.net/FAL/images/blackWalnut-uFonkenSET-comp.jpg)
I have many more examples if you’d like.
If you can afford it, stranded/folized bamboo plywood is an outstanding material that bringsmany of the assets of solid with the benefits of plywood.
dave
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Another possibility is to simply glue a strip of hardwood to the edge of the plywood. A 3/4 x 3/4 piece of hardwood could be glued to the ply edge then another piece of ply attached to that at 90° to form a corner. An advantage of that is you could use a roundover bit to smooth out the look of the edge without exposing any plies.
Another example:
(http://p10hifi.net/tlinespeakers/FAL/images/Phy-HP-8-TQWT.jpg)
dave
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Does having layers of different densities & resonant frequencies also help with reducing resonance, or is it more about mass and thickness?
Contained layer damping works, but IMO the extra efforts bring no real benefits vrs a well engineered box.
dave
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Contained layer damping works, but IMO the extra efforts bring no real benefits vrs a well engineered box.
There's the rub, most affordable speakers don't have a well engineered box. I documented my 2 year journey modifying the Von Schweikert VR2 speakers. All the mods were positive and wrung out every possible improvement these speakers were capable of. The VR2's were built in China to a price point, the crossover was potted so there was no way to see what parts or values were used, drivers were OK but nothing special. After the mods they punched well above what I paid, about 1/2 of retail in a 2006 closeout sale.
Part 2 of the mods document cabinet bracing and woofer damping
https://www.audiocircle.com/index.php?topic=44748.msg400398#msg400398 (https://www.audiocircle.com/index.php?topic=44748.msg400398#msg400398)
Part 3 documents the addition of constrained layer damping inspired by Albert Von Schweikert's triple wall laminate construction article below.
https://www.audiocircle.com/index.php?topic=72808.msg683847#msg683847 (https://www.audiocircle.com/index.php?topic=72808.msg683847#msg683847)
"The Audibility Of Cabinet Panel Resonances and Pat. Pend. Method Of Reduction Of Audible Coloration" by Albert Von Schweikert, Chief Design Engineer, VSA Corp.
https://www.audiocircle.com/index.php?topic=70291.0 (https://www.audiocircle.com/index.php?topic=70291.0)
(https://www.audiocircle.com/image.php?id=20758)
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This has got me curious. I've seen some custom speaker builds onlinr made with inner walls of MDF, and outer walls of solid wood or plywood, (or even metal) while using some sort of rubber/tar adhesive between them to help reduce cabinet resonance. (Before any norez is added)
Does having layers of different densities & resonant frequencies also help with reducing resonance, or is it more about mass and thickness?
This both tips mentioned help.
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There's the rub, most affordable speakers don't have a well engineered box.
I totally agree. Even some very pricey boxes are not that great. I strongly suspect that this is the reason so many like OBs (which i built a few of and heard many more) and they all had a common issue which i could not live with (and i can only suspect what the casue was).
dave
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What are important to a DIY builder are the kind of sound the wood will delivery, I managed to find these characteristics in the CommomSense site some years ago, what match with my experience.
MDF: detailed and bright.
Baltic Birch: soft and warm sound.
Particle Board: neutral, mid on BB/MDF.
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As a diyer i always try to remove any sound from the box, panel resonance, diffraction effects, vented boxes moving out of tune with the dynamics of th emusic or the volume control. I am still learning stuff all the time.
dave
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I totally agree. Even some very pricey boxes are not that great. I strongly suspect that this is the reason so many like OBs (which i built a few of and heard many more) and they all had a common issue which i could not live with (and i can only suspect what the casue was).
dave
Not exactly sure what you are saying. Is it a common issue with the OBs or with the boxes?
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An issue common to every OB i have made or heard.
dave
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What are this? Let us know Dave.
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I still haven’t figured ou thow to describe it. Possibly due to the time smear from the rear radiation.
dave
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An issue common to every OB i have made or heard.
dave
Then we have different experiences, because the best speaker I've ever heard was OB. Better than the Wilsons, the Magicos, or the TADs.
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I fell bored after listening 10 secs of a speaker that emit sound only to front, the back sound wave are part of the music recorded and will make a 3D soundstage to my ears.
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I fell bored after listening 10 secs of a speaker that emit sound only to front, the back sound wave are part of the music recorded and will make a 3D soundstage to my ears.
+1
I heard a pair of Maggies a few months ago at a high end stereo store and they blew my mind away. Have never heard anything like it from boxes.
I'm about to build my first OB speakers. Took a pair of AN Classic 10s out of their ported box and plan to put them onto a simple baffle as a starter. Will go from there as I figure out the room, which is rather small. I know there won't be much bass to start with, but will address that later if the midrange is as good as I expect it to be.