What should speakers be built of ?

[asliarun]

A better link with a lot more details.

Interview with Ryan Scott, Vapor Audio

 

[jls001]

While on the topic of wood, which wood would be best for carving out a heavy turntable plinth from? To be clear, the wood must be a solid block from which the cutouts for motor and arm must be chiselled out, and NOT planks of wood to be glued together (much like plywood popularly used for multi layered plinth constructions).

Or is the whole idea a bit bonkers, without sonic merits? I understand folks like Shindo used planks of cherry wood for their Garrard 301 builds. I was just wondering if using a large block of wood has sonic benefits, especially if it's a known tone wood?

 

[captrajesh]

In my experience MDF, Plastic, Masonite - these three are too dead to make good speakers. you will end having to power your drivers more to get better sound. Having is resonance is not bad.

Interesting! However, I can relate with this view as my first of hifi speakers, made of MDF using drivers from old Kenwood speakers which though dimensionally bigger than the original drivers and without any bracing inside sounded very very good.

The jackfruit tree interestingly is a superb candidate and pretty cheap

Too bad!! I wish this post came a little earlier. I've already procured MDF panels and cut them to size for the GR Research speakers.

Tar is used on the metal horns, exactly for the same reason why they don't make good speaker body material. Horns are extending a compression diaphragm and will have a high frequency ringing which will make the sound very bright/harsh. Tar is used to damp and ensure the metal doesn't ring.

Isn't the tar same material that is in bitumen sheets? I found the bitumen sheets pasted onto the walls of Acoustic Portrait mini monitors that I once had. Also, I have seen the 'No Rez' having a similar layer onto which, PU foam is attached. For those who are not aware of the 'No Rez' offered by GR Research, it is a composite material designed to paste on the insides of boxes made for GR Research speaker kits.

 

[asliarun]

While on the topic of wood, which wood would be best for carving out a heavy turntable plinth from? To be clear, the wood must be a solid block from which the cutouts for motor and arm must be chiselled out, and NOT planks of wood to be glued together (much like plywood popularly used for multi layered plinth constructions).

Or is the whole idea a bit bonkers, without sonic merits? I understand folks like Shindo used planks of cherry wood for their Garrard 301 builds. I was just wondering if using a large block of wood has sonic benefits, especially if it's a known tone wood?

I would imagine that an end grain block would be much better for a turntable plinth as compared to a sheet of solid wood. Stiffness and hardness of wood and "lack of warping" is significantly superior along the trunk (and end grain block) than perpendicular to the trunk (most solid wood sheets). A good example of this is the butcher block which is always an end grain block - and well withstands the pounding from heavy knives without losing shape or even denting much.

But I am only saying this from my experience with knife boards. Normally, availability of a big enough end grain block is the biggest challenge - and hence not more widely used.

 

[Srinath_seshadri]

Granite plinths have been done.
So have acrylic, solid machined metal, hollow machined metal, wood rings inside metal, metal rings inside wood ... anything that could be deemed pretty -
Anyway make it and put pics up.

I found this link again, after being a regular visitor to lampizator for a few years - enjoy.

http://lampizator.eu/VINYL/New turntable Pro-Ject9.html

Cool.
Srinath.

 

[analogadikt]

So whats the conclusion?


Have been using MDF since last few years after I again got into building. I have come across two varieties of MDF here, the commercial which is kind light pink in color and the "green lam" brand which is light yellow and looks much better quality and is denser.

Pink MDF is exterior grade, it is moisture resistant and costlier than the interior grade yellow MDF of the same brand.

I use the exterior grade pink MDF for my speaker builds.

Regards,

 

[Srinath_seshadri]

In the US we refrain from getting much of the outdoor grade wood for interior use. They call it "pressure treated wood" and I dont like using it for any thing in the house. There is some chemicals in it that cause cancer, or other horrible crap.
Cool.
Srinath.

 

[jls001]

TT Plinth: Granite block? Cut and polished to a beautiful finish.

Granite (and marble) is generally not favoured as it rings. The stone of the moment is slate due to its good damping property, and its density (in mass loaded plinth designs where high mass is valued). Sandstone is also good due to similar reasons.

 

[analogadikt]

In the US we refrain from getting much of the outdoor grade wood for interior use. They call it "pressure treated wood" and I dont like using it for any thing in the house. There is some chemicals in it that cause cancer, or other horrible crap.
Cool.
Srinath.

All types of MDF, particle board, plywood are pressure treated. Pressure is used to bind the particles, layers together. Some of the binding agents can cause health problems in case of prolonged exposure; hence certain basic precautions are required when working with these materials. First is to work with them outdoors and wear a nose filter so the sawdust is not inhaled. The finished article should be painted, laminated, papered, veneered etc so the base material is sealed and not allowed to breath.

The advantages of using moisture resistant materials in a tropical humid climate can be deduced easily.

Regards,

 

[navin advani]

Going by your builds, you do look like a guy with loads of talents and experience and equipments as well. Did you ever try TL's?

OMG, don't say that. I am not very active with loudspeakers now, have not been for a while.

But yes I have made TLs. Small ones using 8" Vifa PL series woofers, large ones using 2 JBL 15" woofers, and even a TL that occupied almost the entire trunk of my Contessa car using 3 10" woofers from King Sound (Dhwani Audio). Today a lot of the magic is gone if you use MJK's spreadsheets, you can get some very accurate results.

a. Keep in mind that unless you can MEASURE the T/S specs of your woofer, making TLs is a hit or miss exercise.
b. You can also TL a midrange and they can sound lovely in a TL.

Hope this helps.

In my experience
MDF, Plastic, Masonite - these three are too dead to make good speakers. you will end having to power your drivers more to get better sound. Having is resonance is not bad.

Wood - If you have the money for it, this hardwood is the best choice.

Plywood - This is the most VFM ergo best option.

Having resonance is not bad, but controlling resonance is not easy either.

DaedalusAudio uses hard wood.

In my view pre-stressing plywood by bending it into a curve makes it stiffer and if you use many thin layers you can get a pretty good box.

As I understand, some speaker makers use stacked ply. Like Vapor Audio does.

This method wastes a lot of wood but works well when you have your speakers machine cut. For DIY bending ply is easier.

 

[navin advani]

Thanks for the advice. I have been vacillating but I think should buy the Dayton Audio's DATs for TS measurements before doing all the hard work on cabinets.

Measured specs differ as much as +/- 20% from published specs and this is with the good manufacturers aka Scan Speak, Morel, Focal, etc. hence if you intend building DIY speakers I see 4 options.

a. Stick to sealed box cabinets which are very permissive of differences in T/S specs.

b. Think about horns but these are large and require a lot of trial and error in getting them to sound just right. When they do sound right they can blow your mind.

c. Look at kit speakers where manufacturers have done some degree of QC control on the T/S specs.

d. Get LEAP/LMS, CalSod, Clio, MLSSA or some similar measuring tool to verify T/S specs as well a small room and a microphone to measure in-room response. Don't be overly concerned about the response over 200Hz as that can be managed using placement and treatment. I use to only worry about 30-150hz or so.

 

[Hiten]

While on the topic of wood, which wood would be best for carving out a heavy turntable plinth from? To be clear, the wood must be a solid block from which the cutouts for motor and arm must be chiselled out, and NOT planks of wood to be glued together (much like plywood popularly used for multi layered plinth constructions).

Or is the whole idea a bit bonkers, without sonic merits? I understand folks like Shindo used planks of cherry wood for their Garrard 301 builds. I was just wondering if using a large block of wood has sonic benefits, especially if it's a known tone wood?

I think a glued layered plinth would serve the purpose of isolation and somewhat in lesser quantity as noise drain objective. While as solid wood or unglued layers of ply tightly held by wood pegs would primarily help drain noise from turntable chassis.
Regards.
sorry for being offtopic.

 

[Hiten]

So that's what I have noticed. Feel free to add to this or to correct me.
Cool.
Srinath.

I think not so thin ply with tar sheet and very very well embraced cabinet almost serves the purpose of ideal speaker cabinet. I could be wrong though or may be it is just one alternative option.
Regards.

 

[navin advani]

I am always doing ported ones. I am not sure why, may be the sealed sound boomy to me.

I am serious about acquiring Altec 288's. Comments ?

Is Dayton Audio DATS a good choice for measuring TS parameters? Parts Express has them.

I have finished acquiring most of the drivers (the 2/3 way set ups which I already started before I got to know Alltecs). So kits are out of my profile. Though should have gone the kits-way. Less painful.

Could you suggest a low cost set up for verification? The TASCAM US-122MK2 ? And a good mic etc.

Thanks a lot.

That is odd, unless the drivers you use have T/S specs that favour bass reflex (such as very low Qts), sealed boxes usually can give tighter bass.

I have never used DATS so cannot comment on it. Most of the software I know can accept an input from a PC's sound card. I don't know why you need the Tascam Midi unit.

What horn do you intend to put on the Altec 288? Altec used to sell a matching horn that needed some damping. I would recommend that.

 

[Srinath_seshadri]

Yep, the woofers Qts recommends bass reflex and sometimes a choice between the two.

Yep, would go for that matching horn. There is guy in Germany I know who makes amazing horns. He could be of help as well.

Surprisingly, the 288's too weigh a TON !

I believe these are JABO horns. I'd be a little careful, I dont really like the way fiberglass horns sound. I prefer metal even if its a smaller horn.
In fact some of those university ones are 1/2 the size of the EV ones.
In fact its as big as the 2 center holes of a 811. It will sound so good, you will never want to listed to a fiberglass or plastic horn again.
In fact I even liked those magnavox 4X10 mid horns as well. They are cheap and plasticky for the driver, but the horn is great.
There was a german metal horn - I think Renkus Heinz - those are metal. Those are old though. Not made now.
Metal man, have you ever heard a plastic trumpet.

Cool.
Srinath.

 

[Srinath_seshadri]

Plywood and metal ? Maybe its better than the ones I have heard. No idea.
Cool.
Srinath.

 

[navin advani]

No, he makes multi cell horns out of 4mm to 5mm ply. A work of Art & Science for him. Uses metal finished adapters in between.

This should work. I once made such a horn for a Focal 7N303 and 313 (that was 20 years ago I think). That was based on Bruce Edgar's midrange horn (see if you can find old Speaker Builder articles)

http://petoindominique.fr/php/mysql_thiele_seul.php?hp=5118

http://volvotreter.de/downloads/Edgar-Midrange-Horn.pdf

http://hornloudspeakermagazine.blogspot.in/2007/11/midrange-hornsthe-edgar-midrange-horn.html

 

[analogadikt]

And here is the grandpa of the horn above




This is a pair of Altec 1505 that I have. These are the pre 1958 version, tar filled with brass throat.

Regards,

 

[yugaaa]

How about earthenware ? I used to listen to a lot of music with speakers placed in pots . Probably a box earthenware with tar lining inside and a woodenbaffle stuck with the speaker on the box with the help of M-Seal ?

Probably the box would be "dead as a brick " ?

 

[nosortf]

Different materials work for different frequency decades.
Different materials work for varying driver materials.
But in the quest to be rectangular and sensible, I have found that 15 mm chipboard or what is called particleboard to be the best material, for most driver types except aluminium woofers.
The trick is not just the material but also the bracing.
Effective bracing material in my opinion is BTC shafts.