I don't know what happened. . . .

[MrBoat]

I was cleaning out my workshop a bit, found some mahogany boards, and before I knew it, I pulled the trigger on a pair of Bagby's Continuum speakers. It was the solid wood construction partly and having read about these intriguing little bookshelf. . . . things.

A write-up from Jeff Bagby here.

Most people here are probably already familiar with these speakers, being I have been away from audio with any seriousness in 2 decades while kids were being grown, and very little to do with kit speakers. So, what is new news to me is likely old news to the old salts here.

I have some nice Japanese dovetail saws/chisels so perhaps I can keep myself from out of piecework mode long enough to build something nicer this time. Especially since I am not lacking good music. Perhaps a pair of custom stands to perch them on as well.

And, I did just get that Dayton RSS315HF-4, 12" subwoofer driver recently and it may be a good companion with these.

 

[Swerd]

I was cleaning out my workshop a bit, found some mahogany boards, and before I knew it, I pulled the trigger on a pair of Bagby's Continuum speakers. It was the solid wood construction partly and having read about these intriguing little bookshelf. . . . things.

A write-up from Jeff Bagby here.

Most people here are probably already familiar with these speakers, being I have been away from audio with any seriousness in 2 decades while kids were being grown, and very little to do with kit speakers. So, what is new news to me is likely old news to the old salts here.

I have some nice Japanese dovetail saws/chisels so perhaps I can keep myself from out of piecework mode long enough to build something nicer this time. Especially since I am not lacking good music. Perhaps a pair of custom stands to perch them on as well.

And, I did just get that Dayton RSS315HF-4, 12" subwoofer driver recently and it may be a good companion with these.

I don't doubt that you'll do a great job with the joinery of those mahogany boards. But remember, there is a sound quality reason why MDF or void-free plywood (such as Baltic Birch) is preferred. All solid woods have natural resonances. That may work well for musical instruments, but can interfere with good sound in a speaker cabinet. MDF or plywood has fewer natural resonances.

Equally important is dimensional stability. Hardwoods swell and shrink as humidity changes. They can warp. In a rectangular speaker cabinet, this can result in split joints or cracked panels. MDF and ply remain flat. That's why you don't see speakers with solid hardwood cabinets. Veneer over a flat material like MDF with stable dimensions gives better results.

Maybe you can plane the mahogany down to flat ¼" thick panels and use those as a thick veneer over MDF or ply.

You already ordered the Continuum kits, but you should read up on what the "BBC dip" is in a crossover and how it sounds. It's somewhat controversial, some people like it, and others (like me ) don't.

Here is an example of a frequency response with a pronounced BBC dip. The red line is the on-axis sound. See the dip between 2 and 3 kHz. Right around the crossover frequency.

 

[KEW]

That looks like a neat kit!
Reminds me of the SVS Ultra (Aluminum tweeter and ~2kHz crossover) except for the woofer size!
Since the continuum has a smaller woofer and crosses a little lower, it should, in theory, perform a little better in the upper range of the woofer which is pretty impressive (the Ultra is quite nice)! On the other hand, making the tweeter dig down deeper would, in theory compromise that region. Of course that is in theory assuming the drivers have roughly the same characteristics (obviously they don't since Bagby emphatically states that the KEF woofer is the only driver he could find to work the magic he demanded!).
I looked and did not see the kit for sale without the cabinet. Are you having to buy parts individually or did I miss something?
Look forward to seeing your craftsmanship on that Mahogany cabinet!
If you ever get the chance to A-B them against the Ultras, please do! That would be an interesting read!

 

[Pogre]

I know what happened!

 

[Pogre]

I don't doubt that you'll do a great job with the joinery of those mahogany boards. But remember, there is a sound quality reason why MDF or void-free plywood (such as Baltic Birch) is preferred. All solid woods have natural resonances. That may work well for musical instruments, but can interfere with good sound in a speaker cabinet. MDF or plywood has fewer natural resonances.

Equally important is dimensional stability. Hardwoods swell and shrink as humidity changes. They can warp. In a rectangular speaker cabinet, this can result in split joints or cracked panels. MDF and ply remain flat. That's why you don't see speakers with solid hardwood cabinets. Veneer over a flat material like MDF with stable dimensions gives better results.

Maybe you can plane the mahogany down to flat ¼" thick panels and use those as a thick veneer over MDF or ply.

You already ordered the Continuum kits, but you should read up on what the "BBC dip" is in a crossover and how it sounds. It's somewhat controversial, some people like it, and others (like me ) don't.

Here is an example of a frequency response with a pronounced BBC dip. The red line is the on-axis sound. See the dip between 2 and 3 kHz. Right around the crossover frequency.

I've always wondered why hard woods weren't used more often. I thought it was a cost thing.

 

[Swerd]

I've always wondered why hard woods weren't used more often. I thought it was a cost thing.

Jim Salk, who does some of the best woodwork and finishes in any speaker cabinets I've seen, also does custom made designs for customers who can pay for it. He'll do any kind of veneer that's available and he'll do hand rubbed glossy finishes that look spectacular. These can add thousands to the cost of speakers. But if customers want solid hardwood cabinets, he does his best to talk them out of it.

 

[KEW]

I don't doubt that you'll do a great job with the joinery of those mahogany boards. But remember, there is a sound quality reason why MDF or void-free plywood (such as Baltic Birch) is preferred. All solid woods have natural resonances. That may work well for musical instruments, but can interfere with good sound in a speaker cabinet. MDF or plywood has fewer natural resonances.

Equally important is dimensional stability. Hardwoods swell and shrink as humidity changes. They can warp. In a rectangular speaker cabinet, this can result in split joints or cracked panels. MDF and ply remain flat. That's why you don't see speakers with solid hardwood cabinets. Veneer over a flat material like MDF with stable dimensions gives better results.

Take this with a grain of salt and recognize that it is a subjective sample of one!
When I was first getting back into audio, I listened to many speakers. One of them was the Totem Rainmaker. Totem advertises the resonance of natural wood as part of their design.

I found them to sound wonderful on non-complex acoustic music played at room filling, but casual levels; however, they faired less-well on complex music, especially if played louder.

Here are my original comments on this speaker (read into the Studio20 section).
http://forums.audioholics.com/forums/threads/notes-from-auditioning-speakers.57469/page-4#post-614015

My SWAG ("scientific" wild a$$ed guess) on this ties to the fact that resonance is non-linear. A common example of this is the feedback that can happen on a PA system where everything works fine until a volume threshold is reached where the sound from the speaker excites a resonance in the microphone driver. Backing off the volume just a little bit makes a huge difference.
A solid wood cabinet would not be near so sensitive as a microphone-amplified speaker system, but the same principal applies: Increase the volume from 40 to 60dB may not increase resonance by much, while going from 60 to 90dB (both 50% increases in SPL) is going to result in a proportionally greater increase in resonance.

But, again, I may be full of $hit, it is not like the cabinet material was the only difference between the Rainmakers and the Paradigms I was comparing at the time!

 

[MrBoat]

I don't doubt that you'll do a great job with the joinery of those mahogany boards. But remember, there is a sound quality reason why MDF or void-free plywood (such as Baltic Birch) is preferred. All solid woods have natural resonances. That may work well for musical instruments, but can interfere with good sound in a speaker cabinet. MDF or plywood has fewer natural resonances.

Equally important is dimensional stability. Hardwoods swell and shrink as humidity changes. They can warp. In a rectangular speaker cabinet, this can result in split joints or cracked panels. MDF and ply remain flat. That's why you don't see speakers with solid hardwood cabinets. Veneer over a flat material like MDF with stable dimensions gives better results.

Maybe you can plane the mahogany down to flat ¼" thick panels and use those as a thick veneer over MDF or ply.

You already ordered the Continuum kits, but you should read up on what the "BBC dip" is in a crossover and how it sounds. It's somewhat controversial, some people like it, and others (like me ) don't.

Here is an example of a frequency response with a pronounced BBC dip. The red line is the on-axis sound. See the dip between 2 and 3 kHz. Right around the crossover frequency.

It seems that Bagby is known for making a few controversial designs. The Tempests I own are a Bagby design and there are mixed reviews and I love the sound of them to where I listen to them hours on end nearly every day for months now. Lets also remember that there are speakers designed with perfect measurements that are riding on a heap of room EQ, a variety of crossover selections with subwoofers and a lot of talk of near continuous troubleshooting with measurement tools etc., as part of the sport these days. That this design was chosen as the best sounding small speaker at a few DIY events among quite a number entries.

As far as plywood or MDF vs solid, these are pretty small boxes. One way to mitigate warpage etc, is to rip the boards and alternate the pieces and glue them back together. One of the reasons I am looking at genuine mahogany is, that it's a relatively stable, durable hardwood used in the marine industry because of that. The boards I have stashed I have had for years by now and have completely acclimated to my environment and are not warped. Also this design has the front baffle removable and the rear can be as well so there can be some room for acceptable movement. Add dovetailed corners for the main casework and this should be pretty redundant.

I built this small chest out of ash scraps nearly 30 years ago and it's been abused and forgotten to the garage and it's still together. I have threatened to restore it and bring it back out now that the kids are grown, but it was just a learning exercise in dovetails instead of anything with a purpose. I have others, including a tiny one I made from cherry around here somewhere that has held up as well.

I did read up on that "dip" and it has me somewhat curious as to how close to the measurements do our ears really care. There are a lot of speakers that measure better yet people still choose different brands. You would think that once measurement nirvana was achieved, that there would be no need to look further than any given brand, other than size or power and aesthetics perhaps and everyone would just build their speakers the same. I don't know. I am new to all this and you folks surely know better than I. This may instead teach me where 'not' to go when looking at measurements or what they actually mean to my ears from here on out.

 

[Pogre]

I wonder if living in the desert (like I do) would alleviate some of the issues with swelling and shrinking from humidity? It's pretty dry most of the year here in az. Not that I'm considering a hard wood speaker or anything. Just curious.

 

[MrBoat]

That looks like a neat kit!
Reminds me of the SVS Ultra (Aluminum tweeter and ~2kHz crossover) except for the woofer size!
Since the continuum has a smaller woofer and crosses a little lower, it should, in theory, perform a little better in the upper range of the woofer which is pretty impressive (the Ultra is quite nice)! On the other hand, making the tweeter dig down deeper would, in theory compromise that region. Of course that is in theory assuming the drivers have roughly the same characteristics (obviously they don't since Bagby emphatically states that the KEF woofer is the only driver he could find to work the magic he demanded!).
I looked and did not see the kit for sale without the cabinet. Are you having to buy parts individually or did I miss something?
Look forward to seeing your craftsmanship on that Mahogany cabinet!
If you ever get the chance to A-B them against the Ultras, please do! That would be an interesting read!

It comes as a kit with the drivers, crossover parts and diagrams and other associated hardware.

I did see some post on PE after I already bought the kit and a builder tested them against some pretty stiff competitors, albeit he did end up choosing another commercial design as the best bookshelf he had ever heard which did not surprise me. This kit is rather inexpensive. Maybe it will surprise me.

 

[MrBoat]

I wonder if living in the desert (like I do) would alleviate some of the issues with swelling and shrinking from humidity? It's pretty dry most of the year here in az. Not that I'm considering a hard wood speaker or anything. Just curious.

Sure it would. Furniture holds up better in places like Colorado where there is less seasonal humidity extremes. Besides, most of us live with climate control as well most of the time and this is not the same as things that live in open environments or outdoors.

 

[MrBoat]

Take this with a grain of salt and recognize that it is a subjective sample of one!
When I was first getting back into audio, I listened to many speakers. One of them was the Totem Rainmaker. Totem advertises the resonance of natural wood as part of their design.

I found them to sound wonderful on non-complex acoustic music played at room filling, but casual levels; however, they faired less-well on complex music, especially if played louder.

Here are my original comments on this speaker (read into the Studio20 section).
http://forums.audioholics.com/forums/threads/notes-from-auditioning-speakers.57469/page-4#post-614015

My SWAG ("scientific" wild a$$ed guess) on this ties to the fact that resonance is non-linear. A common example of this is the feedback that can happen on a PA system where everything works fine until a volume threshold is reached where the sound from the speaker excites a resonance in the microphone driver. Backing off the volume just a little bit makes a huge difference.
A solid wood cabinet would not be near so sensitive as a microphone-amplified speaker system, but the same principal applies: Increase the volume from 40 to 60dB may not increase resonance by much, while going from 60 to 90dB (both 50% increases in SPL) is going to result in a proportionally greater increase in resonance.

But, again, I may be full of $hit, it is not like the cabinet material was the only difference between the Rainmakers and the Paradigms I was comparing at the time!

We have to remember also that these are pretty small cabinets. Density changes with regard to scale too. Birch plywood that is often suggested is probably half the weight of MDF and yet it is being used for larger enclosures. Plywood is just more dimensionally stable due to it's alternated layers but it is still comprised of solid wood and the glue lines are very thin so they don't add anything. These small speakers are not SPL monsters either. Add damping, bracing and whatnot, the choice of material in this case probably becomes rather redundant.

 

[Pogre]

Sure it would. Furniture holds up better in places like Colorado where there is less seasonal humidity extremes. Besides, most of us live with climate control as well most of the time and this is not the same as things that live in open environments or outdoors.

I thought so. You make a good observation in your previous post. We buy these ruler flat speakers that measure very well in an anechoic environment then EQ the living crap out of them so they work in our room. lol

I have definitely been listening to a lot more music than I used to before I joined this forum. Listening to my stuff on an upgraded system is almost like having all new music again. I love my system.

I can't wait to see what you do with the mahogany. One thing for sure, I know they'll look amazing.

 

[MrBoat]

I thought so. You make a good observation in your previous post. We buy these ruler flat speakers that measure very well in an anechoic environment then EQ the living crap out of them so they work in our room. lol

I have definitely been listening to a lot more music than I used to before I joined this forum. Listening to my stuff on an upgraded system is almost like having all new music again. I love my system.

Heck, I like your system. If I was buying a commercial set, I would probably have what you chose. It looks right to my eye. I can imagine it sounds as good as it looks!

 

[MrBoat]

I built a wood boat that has been used heavily. It has solid mahogany frames clad in marine plywood with glued construction. It's still in perfect condition. It's been as wet inside as out. The mahogany is sealed well.

The solid wood in this case doesn't really concern me. The removable front (and rear panel, if I so choose) is part of this consideration. There are ways around this. It would likely be expensive for Salk to include this in his practices.

 

[KEW]

It comes as a kit with the drivers, crossover parts and diagrams and other associated hardware.

I did see some post on PE after I already bought the kit and a builder tested them against some pretty stiff competitors, albeit he did end up choosing another commercial design as the best bookshelf he had ever heard which did not surprise me. This kit is rather inexpensive. Maybe it will surprise me.

The kits I saw came with an assembled cabinet!
http://www.diysoundgroup.com/catalogsearch/result/?q=continuum

• 1 - Aruum Cantus 5.25" woofer

• 1 - Dayton Audio RS28A tweeter

• 1 - Fully assembled enclosure

• 1 - Set of crossover parts (optional assembly)

• Screws for woofer and tweeter

• Acoustic foam or polyfill

• Internal wiring

• Terminals

 

[slipperybidness]

@MrBoat
Yeah, I could see how constantly designing speakers to achieve ruler-flat accuracy could get to be a bit tedious, so as a speaker designer it is likely a bit fun to do something different or unexpected every now and then.

But, why another JB design? There are a lot of other designers out there to choose from! If I were to do a JB design, I've really been wanting to do those PE Solstice kits with the all-Morel drivers!

Anyway, just in case you have never seen Murphy Blaster, here is a link. I'm sure you hear us talk about Dennis Murphy and Philharmonic audio, here is a link to his DIY design page:
http://murphyblaster.com/content.php?f=main.html

 

[Swerd]

It seems that Bagby is known for making a few controversial designs…

Jeff Bagby also has an excellent reputation among experienced DIY builders and designers.

The example that I posted above of the frequency response curve of a speaker with a BBC dip is probably an extreme one. When I actually looked at Bagby's frequency response curve on page 2 of his write up, it looked pretty good to me (see below). I'd call that flat within two octaves of the 1.8 kHz crossover. So I spoke too soon.

I did read up on that "dip" and it has me somewhat curious as to how close to the measurements do our ears really care.

Our ears are most sensitive to variations in the mid range. We can detect changes smaller than ±1 dB in that range. At the extremes of the audio band, we are much less sensitive.

There are a lot of speakers that measure better yet people still choose different brands. You would think that once measurement nirvana was achieved, that there would be no need to look further than any given brand, other than size or power and aesthetics perhaps and everyone would just build their speakers the same.

There are measurements and there are preferences. Some people like a flat frequency response and others don't. People's preferences often have a lot to do with what speakers they have become used to hearing. That can vary all over the map.

As far as plywood or MDF vs solid, these are pretty small boxes…

Yes, and their small size is a key point. Maybe you can get away with using that mahogany. You certainly have the experience. It might help to seal the inside and outside surfaces of the cabinet.

For what it's worth, Jim Salk does build and sell a version of Bagby's Continuum. Note all the screws on the front baffle.

 

[Pogre]

$1300/pr for the Salk version. That's getting into very good bookshelf speaker territory price wise.

 

[shadyJ]

Things can be done to damp resonances, so that wood might not be a bog deal. Line the interior with some kind of viscoelastic material, and then stuff the cabinet chock full of Dacron. Install extra bracing. I think that will be enough to eliminate resonances from almost any kind of wood.