custom hardwood heresy cabinets

[Johnthang]

Does anybody see a problem with making custom hardwood cabinets for a pair of  herseys. Im thinking quartersawn white oak and padauk panels, dovetailed, for the carcass. I'm thinking sound quality should not change. Any ideas??? 

Edited May 30, 2015 by Johnthang

[Frzninvt]

Hardwood is not dense enough and will resonate like crazy.  You need to use mutli-layered baltic birch or equivalent and veneer it in the wood of your choice.  They have been making them that way since 1957 for a reason.

[WMcD]

It sounds like you are about to create a masterpiece.

I would not hesitate because of concerns over resonance. The early ones were ply and the later ones MDF, to my understanding.

If there is a problem with resonance, some cross bracing inside should take care of it.

WMcD

Edited May 31, 2015 by William F. Gil McDermott

[jimjimbo]

Hardwood is not dense enough and will resonate like crazy.  You need to use mutli-layered baltic birch or equivalent and veneer it in the wood of your choice.  They have been making them that way since 1957 for a reason.

Agree with this completely.

[prerich]

I agree with the resonance issue. Klipsch is not the only speaker maker that uses birch plywood for cabinets, Audio Note UK also uses Russian Birch for their cabinets, these cabinets are actually tuned because of their wood properties 

(from my understanding FMU). 

[WMcD]

I think John deserves our support.

Using ply or MDF for production units makes economic sense.

I don't know that anyone tried solid panels and joinery. I've not seen comments by anyone who actually built something like John proposes and found them lacking because there was some sonic problem.

If John has the inspiration, time, money, and skills, I'd say, go for it.

John, post pictures, please.

WMcD

Edited May 31, 2015 by William F. Gil McDermott

[mustang guy]

The glue in plywood dampens resonance. If you made a speaker with solid Baltic Birch, it would resonate. I don't know if it would work, but there is a product called Lizard Skin that is used for cars to deaden resonance. If I were a cabinetmaker and had a pile of cherry, I would experiment with this stuff by coating the inside with it. You might want to make the motorboard and the back cover from BB plywood.

 

I think it would be a beautiful project!

Edited May 31, 2015 by mustang guy

[jimjimbo]

John asked for technical advice and he is getting our support..  It is obviously not about economics, it's about resonance and sonics.  And, apparently he does have the inspiration, time, money and skills to do whatever he decides will look the best, AND sound the best.

 

Klipsch does not make speakers of 100% hardwood

Bowers and Wilkins does not make speakers of 100% hardwood

Selah does not make speakers of 100% hardwood

 

Find some high quality Baltic Birch, veneer with some beautiful wood of your choice if you are really stuck on creating from scratch...

 

or....

 

Find a nice pair of gently used Heresy's, reveneer, and voila!  

[WMcD]

The side panels are about 1 foot x 2 feet and are completely secured at the four edges. How much can that resonate?

The top and bottom panels are even smaller.

The front is stiffened by the drivers.

The back panel John hasn't mentioned but presumable will be ply or MDF, or even joined hardwood. If there is some resonance issue, a bit of reinforcing will solve it.

WMcD

[Coytee]

Dumb question time....

 

If you already have a donor speaker on hand....  could he not built his solid wood speaker a bit larger to envelope his existing speaker, making it a speaker 'in a box'.

 

This would give him the proper internal volume and the exterior of his choice.

 

Yeah, I know it would be bigger & heavier.  Might even be a dumb idea.....  but it would work, wouldn't it?

[Fjd]

I think John deserves our support.

Using ply or MDF for production units makes economic sense.

I don't know that anyone tried solid panels and joinery. I've not seen comments by anyone who actually built something like John proposes and found them lacking because there was some sonic problem.

If John has the inspiration, time, money, and skills, I'd say, go for it.

John, post pictures, please.

WMcD

 

 

I tend to agree with what Gil has written in several posts. 

 

Sometimes it sure does seem that instead of speaking from direct experience some just want to create a “straw man” to attack by naming manufacturers that don’t use solid wood (implying solid wood must be bad) in an effort to refute the original proposition; that while wood will have different [or more] resonate peaks and different damping properties, the peaks and damping properties may just be something different that may require a different manufacturing process, which may not be very economical to address for mass production. 

 

Let's break this down somewhat and "peel back the veneer" so to speak and see what we can come up with.

 

Think about the ideal enclosure for a moment.  I believe the general description is something like that for any driver the enclosure would not contribute to its sound beyond the elimination of the back wave.  Various colorations introduced by the cabinet would most likely be considered a distortion of the original signal. 

 

Essentially, the ideal loudspeaker enclosure most likely should be highly rigid, highly damped, and does not impact the individual driver's reproduction of the pitch or tone of individual acoustic instruments in the recording.  For example, in a well-recorded piece of music, can I tell whether a Stradivari or a Guarneri violin was used in the recording or does it just come across as an ordinary fiddle?

 

Any speaker box designer will understand that there are compromises and that no single material will be ideal for both bass enclosures and midrange enclosures, and why many times we see that loudspeaker cabinets incorporate several technologies to optimize the system.

 

I suspect that a heresy-sized box for home use will not get the pounding of a sound reinforcement speaker and I agree with Gil that the resonant peaks most likely will be nothing extreme for which smart bracing shouldn’t cure. 

 

Given the above, all materials, including composites, will still resonate.  Understanding the resonate peaks and cavities through measurements and figuring out ways to incorporate or eliminate these box resonances are sometimes just part of designing speaker enclosures.  

 

An aspect that seems important in speaker box design is that I believe a person needs to determine if the resonant frequencies occupy a single band or determine if the resonant frequencies of the speaker enclosure lie outside the range where the drivers operate.  Essentially, I suspect that you will find that there are “different” resonate peaks and cavities depending upon the material used in combination with the drivers used and the overall Q of the box design.

 

Shoot, the Khorn (peak at 50Hz, cavity at 40Hz), La Scala and Cornwall all have some level of resonate peaks in the bass area.  

 

I don’t remember exactly where the Cornwall resonate peak exists, but I believe that it is this “hump” that is part of what gives it the impactful bass.  

 

In addition, even Klipsch used fiberglass for some of their pro La Scala speakers.    

 

Those that add the braces to the La Scala bass horn also note a different sound as the resonance of the La Scala box/horn has been changed by adding the brace.

 

There again, as Gil stressed, proper bracing can eliminate various resonate peaks (or move the resonate peak outside the range of the driver) in many materials such as wood or plastic and can net better sounding, and much lighter, build results.  However, there is no “free lunch” as the bracing adds construction time, complexity and expense, which few are willing to pay for in a commercially produced speaker.

 

I see the OP has quarter-sawn white oak and padauk panels.  I suspect that the type of “cut” will most likely impact the resonance of the cabinet too. 

 

The type of cut that results in the position of the annual rings is important since wood tends to cup in the direction opposing the curve of the annual rings and I’m sure many have had experience with flat-sawn wood cupping upwards.

 

However, when using quarter-sawn wood the annual rings will be nearly perpendicular to the face grain and will be essentially “cup resistant."  In addition, overall, quarter-sawn wood is much more stable than flat-sawn wood; and expands and contracts much less.

 

The quarter-sawn white oak and red oak are easy to find (vs other types of wood) and the cut tends to reveal a ‘ray-like’ look and add a very cool dimension to the appearance.

 

Here is a post where I explained the different types of wood veneer cuts, which would also apply to solid wood.

 

 

 

Interesting grain structure.

 

 

I suspect that we are primarily looking at a quarter-sawn veneer or maybe rift-sawn as opposed to the more-familiar flat-sawn veneer that we see on speakers.

 

While the grain structure is what makes the quarter-sawn cut more desirable for many people for zebra wood projects, a flat-sawn cut would give more of the traditional look that we typically see. 

 

Unless a special order, we typically see more flat-sawn veneer on speakers because the flat-sawn method of cutting the log is the cheapest to do and has the least amount of waste.

 

Sometimes I read the debates on the woodworkers forums and the acoustic guitar forums for arguments about the best method to cut the wood for a particular piece of furniture or best method to cut the wood for a part of a guitar and a lot about grain orientation.

 

The pictures below show how the grain structue of a wood board changes for the different types of cuts.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

To provide a little perspective regarding the various materials in relation to use in speaker enclosures, the descriptions, critique, and measurements below were taken from the Wilson Audio website.

 

 

MDF (particle board) is by far the most popular cabinet material. It's inexpensive and easy to mill. But as the graph shows, it has three resonant peaks (poor monotonicity). The high, sharp peaks indicate poor damping, and the resonant frequency lies in the 350hz range, (right in the midbass).

 

 

 

 

 

 

This is a graph for oak, a common hardwood. Notice the multiple sharp peaks, indicating a broad resonant frequency spectrum, with poor damping, centered at 558hz.

 

 

 

 

 

 

Baltic birch plywood shows a marked improvement in both damping (notice the smaller, blunter peaks) and resonant frequency (469hz), but the multiple peaks still indicate a material that is far from monotonic. From a practical standpoint, plywood is inexpensive (like mdf) and easy to mold and machine.

 

 

 

 

 

Aluminum (6061-T6 Aircraft Grade) is the real curiosity here. It's a very expensive material, but, as the graph shows, in regards to resonant frequen(cies) and damping, it's a real train wreck. Two widely separated peaks, both of which fall within the midrange. Note also the black line on the left, at 0hz, which indicates the material actually flexing upon impact (poor rigidity).

 

 

 

 

 

Finally, we come to Wilson's X Material.

Notice the resonant peak at 34 db (an average of 10 db lower than most of the competing materials). It also has the shortest decay time (around 7 msec.). Because it's resonant frequency is at 1064 hz, X material is used for bass enclosures, where it's properties translate into the clean, dynamic, and impactful bass response that is the hallmark of Wilson Audio loudspeakers.

 

 

 

 

 

 

"Is that a real poncho, or is that a Sears poncho?"  Of course, when it comes to real wood vs. fake wood there will be design trade-offs, compromises, and many very different things to consider including the much higher costs involved when working with real wood......

Edited June 1, 2015 by Fjd

[mungkiman]

High end speaker builders like Oswald Mill and Daedalus use solid hardwood. Solid hardwood has less dimensional stability than ply/MDF, making it better for small speakers than large ones. Go for it, and please post pictures.

[jorjen]

With a cabinet that small made of Oak with a front baffle and cabinet back installed, you guys honestly think the resonance will be worse than standard Heresy construction(any variation)? I don't.

 

Something with larger un-braced/supported surfaces, yea maybe, but I just don't see it with a Heresy sized cabinet.

[jimjimbo]

GLWS

[ricktate]

I have braced the back panel of my H1s and can feel the difference. Not sure if there is a sound difference. If he does make them out of solid wood he should seal them inside and out to prevent moisture getting in and out of the wood. But they would be cool to see and hear I think. Rick

[djk]

"Oswald Mill"

 

Their preferred cabinet is bamboo.

 

" If he does make them out of solid wood he should seal them inside and out to prevent moisture getting in and out of the wood"

 

That might work, otherwise I'm afraid it's splitsville (with changes in temperature and/or humidity), and I would use quarter-sawn (only).

 

I would also use 3/8" and glue 3/8" Celotex to all inside panels (eliminates resonance and sound transmission through the panels, better than untreated 3/4" material). Portable BBC monitors used this Celotex over 3/8" ply construction, and it tested better than 3/4" ply with fiberglass lining.

[Karsoncookie]

I'm no where as educated and experienced as many of you, nor do I have a "properly" discerning ear.

 

So I may very well be wrong here.

 

But , IMHO, if you blind A-B'd the OP's proposed wood cab's (sufficiently braced, made of sufficiently dried and 4/4 minimum,(I'd use 8/4)wood) compared to baltic birch ply or MDF, you'd never tell the difference.

 

And, if you did, it would be inconsequential. 

 

Probably the main reason sheet goods are used in commercial production is economy (in various ways)

and consistency and assembly line repeatability. 

 

Ok, they show some sonic advantage in labs, does it really matter? 

 

My opinion, I think alot of this is over the top, in some crazy search for "perfection".

 

Some sort of psychological quest for satisfaction.

 

Like having a great sound system and screwing with high end cables,pebbles in baggies, and strategically placed stickers on your walls.

 

Just my opinion, based on my minimal experience.

 

I just know in my younger years I worked toward perfection in everything I made, which was alot of varied things, until I discovered, years later,for myself anyway, it was silly and a waste of effort, and would not matter once it was done and in use.

 

Such diminished returns, ridiculous ROI on time, effort, and money.

 

Johnthang - enjoy building and listening to your Creation.

 

Lars

[djk]

"Just my opinion, based on my minimal experience."

 

And in my opinion, solid wood needs to be quarter-sawn, after being de-lignified, and then the finished piece sealed.

 

Solid wood shrinks and cracks otherwise, that's one reason why good pianos are kept in temperature and humidity controlled rooms.

 

"When wood is cut fresh it has moisture throughout the wood fibers. More in the softer cambium and sapwood areas, and less in the denser heart portion. As the wood slowly dries, the moisture reaches a point where the outside ambient moisture and the wood are equal.It still isn't stable yet. The point of stability comes when the core of the wood and the surface of the wood are the same. On woods that are very dense (ebony, ironwood, etc.) this can take many years. Until this point is reached, it still can crack because it is unstable .
Movement of the wood after being finished is a result of the wood gaining and loosing moisture content due to absorption. This can be reduced by stabilizing with a resin or oil. If the entire exposed surface is not sealed, the wood will still warp."

[mustang guy]

"Oswald Mill"

 

Their preferred cabinet is bamboo.

 

" If he does make them out of solid wood he should seal them inside and out to prevent moisture getting in and out of the wood"

 

That might work, otherwise I'm afraid it's splitsville (with changes in temperature and/or humidity), and I would use quarter-sawn (only).

 

I would also use 3/8" and glue 3/8" Celotex to all inside panels (eliminates resonance and sound transmission through the panels, better than untreated 3/4" material). Portable BBC monitors used this Celotex over 3/8" ply construction, and it tested better than 3/4" ply with fiberglass lining.

 

I like the idea of this, but Celotex is a brand so it's not enough information. Also, it doesn't mention if the layers have opposed grain, which I would assume they do.

 

This method seems the most promising. It is home made 2 ply 3/4" plywood. As I stated earlier, the glue in plywood dampens the natural resonance frequency of solid wood layers it is made up of. Perhaps bamboo tends to have a resonance frequency that is above the human threshold of hearing. Are there any labs who have tested resonant frequencies of differing woods (and grasses as is the case with bamboo)? Is that what fjd showed us above? I have trouble with waterfalls plots, especially if they are not high enough resolution to read properly.

 

edit: It seems like instrument manufacturers have the data we may need to further think this through. Unfortunately, bamboo and birch are missing...

 

click image to open site...

 

Edited June 1, 2015 by mustang guy

[mungkiman]

"Oswald Mill"

 

Their preferred cabinet is bamboo.

 

https://www.facebook.com/oswaldsmillaudio

 

http://oswaldsmillaudio.com/process