All the speakers I made - suri

[keith_correa]

This is the work of one man - and others (one exception) have not tried their hand

Suri, can you please let me know who this exception is?

 

[suri]

Suri, can you please let me know who this exception is?

well, Keith, -

from wikipedia - "This type of loudspeaker enclosure was proposed in October 1965 by Dr A.R. Bailey and A.H. Radford in Wireless World (p483-486) magazine. The article postulated that energy from the rear of a driver unit could be essentially absorbed, without damping the cone's motion or superimposing internal reflections and resonance, so Bailey and Radford reasoned that the rear wave could be channeled down a long pipe. If the acoustic energy was absorbed, it would not be available to excite resonances. A pipe of sufficient length could be tapered, and stuffed so that the energy loss was almost complete, minimizing output from the open end. No broad consensus on the ideal taper (expanding, uniform cross-section, or contracting) has been established".

but - for martin J. king - a transmission line is one in which the remote terminus adds to the (SPL) output of the bass driver - he sought to end the confusion, debate, creativity regarding these (unknown) systems - and also sought to kill off the occasional idiot who tried to design a transmission line loudspeaker -

anyways, not many of these around no more - out of 10,000 DIY'ers who design loudspeakers there would/could be ONE who dabbled in transmission line designs- and for this one - THERE IS NOBODY TO VALIDATE HIS DESIGN - EXCEPT, GUESS WHO? -

and i do not think that those (few) commercial transmission line loudspeakers that are being sold today were developed using martin's guidelines -

i, of course, would welcome a slash and a riposte from a member (commercial or DIY) who has actually developed a superb loudspeaker based on the work of this extraordinary person (whose work has much merit)

and Keith, i can see that in these modern times - there are many DIY'ers with access to (computer) hardware, software and test-measuring equipment - all very good for ported and closed systems - many of these probably come up with good designs - but, after that, have no idea how to construct a good cabinet for their design.

all the successful commercial manufacturers have one thing in common - "they have mastered the "black art" of speaker design - and beyond that -"the art of construction of the speaker cabinet" - (Sonus Faber has touched the moon - in this respect)

nobody is going to build any reference loudspeaker using cut planks of plywood and metal screws (no matter how much computer theory supports the design) - it just will not work.

i still believe that loudspeaker design and construction is a 'black art' - but more "accessible" in these modern times for them gentlemen who "can see beyond the obvious"

 

[keith_correa]

all the successful commercial manufacturers have one thing in common - "they have mastered the "black art" of speaker design - and beyond that -"the art of construction of the speaker cabinet"

Given your experience in cabinet building, can you share and list down points that contribute to a well constructed cabinet. I'm sure many of us will find it helpful. I know I will.
As for the "black art" of speaker design - care to elaborate?

 

[suri]

Given your experience in cabinet building, can you share and list down points that contribute to a well constructed cabinet. I'm sure many of us will find it helpful. I know I will.
As for the "black art" of speaker design - care to elaborate?

sure -

i will start with one -

"do not use plywood sheets as sides for a loudspeaker" (especially, reference loudspeakers)

 

[suri]

Given your experience in cabinet building, can you share and list down points that contribute to a well constructed cabinet. I'm sure many of us will find it helpful. I know I will.
As for the "black art" of speaker design - care to elaborate?

secondly -

"never use metal screws to fix and secure the six sides of a loudspeaker (made-of wood/plywood) cabinet"

 

[suri]

As for the "black art" of speaker design - care to elaborate?

there is a saying -

and it goes likes this -

" for every successful loudspeaker there are are three hundred and eighty nine simulations and actual constructions"

these failures find their place in the attic - the garage - wherever - before the designer finds an acceptable compromise -

but - the (idiot) cognoscenti would have you believe that theory available on the world-wide-web will lead to "first success-first time"

 

[keith_correa]

do not use plywood sheets as sides for a loudspeaker" (especially, reference loudspeakers)

never use metal screws to fix and secure the six sides of a loudspeaker (made-of wood/plywood) cabinet

What is wrong with plywood sheets? What do you feel is best in lieu of plywood? And by the sides do you mean all 6 walls of the cabinet? What if the whole cabinet inner is lined with thin rubber sheets - like the ones used for bicycle tyre tubes?

Similarly, what is wrong with using metal screws? What is recommended instead? And why?

 

[captrajesh]

What is wrong with plywood sheets? What do you feel is best in lieu of plywood? And by the sides do you mean all 6 walls of the cabinet?

Similarly, what is wrong with using metal screws? What is recommended instead? And why?

Yes, even I want to know.

 

[suri]

@keith_correa
@captrajesh -

here is a project using metal screws on a loudspeaker cabinet-

Good Rubbish: I HAVE BEEN COMMISSIONED - CALL ME THE COMMISH.

but apart from that - there are two reasons why metal screws not not be used in construction of a (good) louspeaker cabinet -

1. use of screws implies that there will be greater pressure at the site of the screw than on the other lengths of the side-wall where there are no screws - this high-pressure conglomerate (of wood, metal and glue) acts as an small epicenter of resonance and adds to the resonance of an already resonant cabinet - the larger the number of screws - the more this effect - leading to a cabinet that 'sings'

the six walls of the loudspeaker cabinet must come together with even pressure along the mated lengths - and how does one do this?

in the link below look at "dovetail joints"

Wood joints, Joining wood, Dove tails, rebates, mitres

2. depending on the length, size, mass and type of metal - metal fixators will resonate at some frequency and if the resonant frequency is below 18 khz......


What about plywood? -

Plywood (by nature of its construction) is not uniformly dense - it has air-cavities, and the cheaper plywood varieties using different types of wood - trapped air will resonate at frequencies of interest to us (listeners) - and a two-way loudspeaker made of plywood usually ends up with seven transducers making music (two electrical {woofer and tweeter} and five plywood sides) -

So, if not plywood - what?

MDF is better as far as uniform density is concerned - and it is much easier to work with than plywood - even so, MDF should not be used in the form of planks and sheets -

Particle board (chip board) is cheaper than MDF and that is why Bose and Bowers & Wilkins use it -

HTGuide Forum - A look inside the B&W 683......literally

 

[goldyrathore]

Suri,

You seem to be conradicting what has been published here as far as your comment on avoiding plywood goes:-
Cabinet walls and Loudspeaker Energy Preservation - [English]
While your comments are true that ordinary ply with voids is a bad choice, there is a variety of void free plywood available, I dont seem to remember what it is called. Marine grade ply??

Even rethm uses ply.
Saadhana - Rethm Loudspeakers


Also the metal screw resonance is too simply put. The fear of screws must have a sound ground.
1) Does not the resonance reduce (in peak) with every additional screw put?
2) Does it not vary in frequency depending on where the screw is put thereby ensuring that the resonance of any two screws is not going to be same.
3) How is it concluded that the problem is so severe that it cannot be dealt with and screws should be avoided as a result?
4) Isn't it true that even a well treated room will have far more detrimental affects on sound than the screw-board-resonance?

Some pointers of existing work will really help in understanding whether it really is an issue and the use of screws is a bad compromise.

Speaker design is all about making the right compromises. Engineering makes us make the right decisions on informed choices. When some things are not understood it is assumed to be art. Yes there are many things still not known about sound/speakers but we do come across studies which provide scientific basis of why things work and why they dont and then it is black art no more. From then on it becomes science/engineering.

For example :-
1) Till some time ago it was assumed that ported boxes could not be Eqed. It was more of trial and error, till some studies were done. http://www.cordellaudio.com/loudspeakers/EQSS_White_Paper.pdf
http://www.interdomain.net.au/~bodzio/Article1.pdf

2) It was known that distortion (as in specs) was not a good indicator of the sonic signature of an amp. Then people figured out that lower harmonics were not bad as compared to higher harmonics and its common knowledge now. It is no more an art. Now we know that beyond a particular level majority of us cannot pervieve the difference between two types of amps with a different distortion signature.

3) Even today many choose amps by looking at damping factor. But look at this http://documents.jordan-usa.com/Fam...ping-Factor-and-Damn-Nonsense-Floyd-Toole.pdf

4) For many manufacturers, they would like to project that speaker design is a black art because it makes them differentiate wrt the competition and sell their products. Cables, Interconnects and Other Stuff - The Truth

I would really take your "Speaker design is black art" statement with a pinch of salt. Sound egnineering can help us to get to a very staisfying level of percieved sonic performance. Beyond which, when things are not known/measured/understood, black art comes to the rescue but by then we are already in the territory of law of diminishing returns. Zaph|Audio

Also I hope my view is taken objectively.

Regards,
Goldy

 

[suri]

Suri,
Even rethm uses ply.
Saadhana - Rethm Loudspeakers

Also the metal screw resonance is too simply put. The fear of screws must have a sound ground.
1) Does not the resonance reduce (in peak) with every additional screw put?
2) Does it not vary in frequency depending on where the screw is put thereby ensuring that the resonance of any two screws is not going to be same.
3) How is it concluded that the problem is so severe that it cannot be dealt with and screws should be avoided as a result?
4) Isn't it true that even a well treated room will have far more detrimental affects on sound than the screw-board-resonance?

hi goldyrathore -

the plywood used in rethm speakers is supplied from Kannur (where i live) - and i have been to Cochin to deliver one consignment of plywood (with a friend who manufactures that plywood - this same person supplies the plywood that is used inside the door frames of mercedes benz)-

the rethm loudspeaker does not use plywood for the working parts - the plywood used is decorative concealment side panels for the working parts, and the working parts are PVC pipes

about the screws - i do not know whether what you say is true or not - but this i know-

none of the high-end loudspeakers use nails or screws for cabinet construction - not even Bose - and no, not even Sony.
there must be a reason for this (and it should be undesirable re.....) otherwise those companies would be vying with each other to put as many nails and screws as possible - but i will find some references for you and post them -

i, personally, know quite a few manufacturers of expensive loudspeakers (some with cheap drivers!) but none of them use screws and nails.

 

[goldyrathore]

the rethm loudspeaker does not use plywood for the working parts - the plywood used is decorative concealment side panels for the working parts, and the working parts are PVC pipes

Can you provide more links to bring out the disadvantages of plywood?

about the screws - i do not know whether what you say is true or not - but this i know-

none of the high-end loudspeakers use nails or screws for cabinet construction - not even Bose - and no, not even Sony.
there must be a reason for this (and it should be undesirable re.....) otherwise those companies would be vying with each other to put as many nails and screws as possible - but i will find some references for you and post them -

i, personally, know quite a few manufacturers of expensive loudspeakers (some with cheap drivers!) but none of them use screws and nails.

The speaker cabs are not designed to dismantle the cabs in service so where is the need of screws? (Its the same thing as why remote boxes dont have screws: coz they are held together by clip-on plastic locks and never designed to be repaired.) At the most the drivers are mounted on screws so that they can be taken out in case of repairs. Or access is provided from the rear of the cabinet which is secured with screws/nuts. Glues are probably cheaper/quicker in production houses, though I am not really sure of this one. The grills are stuck to plastic frames(Sony) around the baffle . Dont you think they will rattle more than any advantage the manufacturer gets by avoiding screws? Also see the cabs carefully on the edges (again Sony satellites), they have the edges joined by tapering the edges at 45 degrees so that each edge sits perfectly on the other edge. The surface area is increased as a result of the taper, making it very easy to glue to get the box up and running.

Though you did bring out interesting topics, what I am interested in it is how good (or bad) the compromises (misfits) are in real world situations. I assume your choices have been based on some study/material/theory/examples, which is what I feel can explain what you have mentioned, more concretely.
Only then can we conclude whether it is a problem to be fixed.

Regards,
Goldy

 

[suri]

goldyrathore -

will dive into the mountain which has the fountain of knowledge soon (WWW)-

but -

plywood is known to be good for guitar cabs - especially if it has voids - because it is resonant -

birch ply is supposed to have nil voids - and if one must use plywood for constructing full-range loudspeakers void-free plywood must be used -

the best plywood available here is marine gold - but even that has voids-

even if birch ply is used - the translam method of construction is better than using them as sheets for the sides.

 

[ajay124]

@suri,goldyrathore
After a long time an interesting HiFi discussion on the forum.Keep it going.

 

[suri]

@suri,goldyrathore
After a long time an interesting HiFi discussion on the forum.Keep it going.

@ajay124-

i have made arrangements for visit to Porvorim after you have settled in.

By witchesofsound at 2010-12-09

witch heart being moved home

By witchesofsound at 2010-12-09

next to witches of ecstasy -

By witchesofsound at 2010-12-09

using thor's hammer to push out the sealing block -

 

[ajay124]

@suri
In the first picture the Witch Heart seems poised for take off.
Will you be flying down to Porvorim on it?Does it double as a broomstick
Congratulations on completing the witch hearts.

 

[suri]

@suri
In the first picture the Witch Heart seems poised for take off.
Will you be flying down to Porvorim on it?Does it double as a broomstick
Congratulations on completing the witch hearts.

ehehehe!

yes, does look like a fat broom-stick!!!

oh, but "witch heart" is about 2 months away from completion!

i have not got the driver and the keiga amp yet - and the sanding and lacquer is yet to start -

i will be very sorry to reach the end and complete the project!

BTW (by the way) - i am (right now) listening to Leonard Cohen's -Essential Collection - Disc 1 - the recording seems to be horrible - all over the place - ????

but, oops, - last song " tower of song" - is so pregnant with meaning for me - aaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhh!!!!

 

[ssf]

That is quite a bold design (and this coming from someone who knows nothing about sub-woofer designs hehe). But I should not be judging a sub-woofer by it's cover.So, if the ground that I walk on is shaken and stirred, I know whom to blame. My friendly neighborhood DIY genius, Suri.

Regards,

@ss.

 

[ajay124]

@suri
BTW (by the way) - i am (right now) listening to Leonard Cohen's -Essential Collection - Disc 1 - the recording seems to be horrible - all over the place - ????
but, oops, - last song " tower of song" - is so pregnant with meaning for me - aaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhh!!!!

I presume you are referring to this 2 CD set.
http://images.uulyrics.com/cover/l/leonard-cohen/album-essential-leonard-cohen.jpg
Although this cd is claimed to have been remastered,the sound on CD 1 is at best average.It picks up and gets better from Hallelujah.But I find the SQ of CD 2 is quite good,especially in the last 5-6 tracks.
A perceptive review from the Amazon archives
Amazon.com: Profile For Jesse Kornbluth: Reviews
YouTube - Leonard Cohen: The Stranger Song

"Stranger Song"/LEONARD COHEN
It's true that all the men you knew were dealers
who said they were through with dealing
Every time you gave them shelter
I know that kind of man
It's hard to hold the hand of anyone
who is reaching for the sky just to surrender,
who is reaching for the sky just to surrender.
And then sweeping up the jokers that he left behind
you find he did not leave you very much
not even laughter
Like any dealer he was watching for the card
that is so high and wild
he'll never need to deal another
He was just some Joseph looking for a manger
He was just some Joseph looking for a manger
And then leaning on your window sill
he'll say one day you caused his will
to weaken with your love and warmth and shelter
And then taking from his wallet
an old schedule of trains, he'll say
I told you when I came I was a stranger
I told you when I came I was a stranger.
But now another stranger seems
to want you to ignore his dreams
as though they were the burden of some other
O you've seen that man before
his golden arm dispatching cards
but now it's rusted from the elbows to the finger
And he wants to trade the game he plays for shelter
Yes he wants to trade the game he knows for shelter.
Ah you hate to see another tired man
lay down his hand
like he was giving up the holy game of poker
And while he talks his dreams to sleep
you notice there's a highway
that is curling up like smoke above his shoulder.
It is curling just like smoke above his shoulder.
You tell him to come in sit down
but something makes you turn around
The door is open you can't close your shelter
You try the handle of the road
It opens do not be afraid
It's you my love, you who are the stranger
It's you my love, you who are the stranger.
Well, I've been waiting, I was sure
we'd meet between the trains we're waiting for
I think it's time to board another
Please understand, I never had a secret chart
to get me to the heart of this
or any other matter
When he talks like this
you don't know what he's after
When he speaks like this,
you don't know what he's after.
Let's meet tomorrow if you choose
upon the shore, beneath the bridge
that they are building on some endless river
Then he leaves the platform
for the sleeping car that's warm
You realize, he's only advertising one more shelter
And it comes to you, he never was a stranger
And you say ok the bridge or someplace later.
And then sweeping up the jokers that he left behind ...
And leaning on your window sill ...
I told you when I came I was a stranger.

 

[ajay124]

@suri
'towers of song' would be a nice name for a future pair of front speakers you build for yourself or someone else