Small Thor ML-TL Transmissionline speaker project

[asliarun]

Thanks kapvin.

Most likely it will be cherry finish, Mahogany also looks beautiful. I am getting the spikes machined next week.

I do not know to calculate speed of sound through of Dacron, pls throw some light on it.

The long wool fibers generally better at attenuating than Dacron at low frequencies, even fiberglass have much smaller fiber diameters and much better attenuation at high frequencies. It's hard to find long fiber wool here but fiberglass is a nasty stuff to handle.


Regards,
Anil

Hi Anil,

You have made amazing progress, and your speakers are looking really good!

How did you fit the input terminals or binding posts? I thought I saw a circular plastic shape in one of the "in progress" pictures. Is this available in India?

What did you do for sealing as well?

Have you also kept the back (or baffle) removable via screws?

Thanks,
Arun

 

[Anil kumar]

How did you fit the input terminals or binding posts? I thought I saw a circular plastic shape in one of the "in progress" pictures. Is this available in India?

What did you do for sealing as well?

Have you also kept the back (or baffle) removable via screws?

Thanks,
Arun

Input terminals are from MX, quality of square terminals are better than a circular one as they are made of thick quality plastic i could not get them as they are out of stock. You should get it in any MX shop at your place. Terminals have holes for 4 mm screws for fixing.

For sealing i am using foam gasket between the driver and the baffle to prevent any air leak they are 1/2" wide & 1/8" thick made of foam material with self adhesive type, very very useful.

Cabinet is completely sealed, so no air leaks or panel vibrations. You can add or remove Dacron stuffing by removing the drivers, you have access only from front.


Regards,
Anil

 

[avidyarthy]

Uffffgh ........ stupendous.

The brush alum amps are ..... just can't take my eyes off them. And your DIY speakers ....... 'pure' as extra-marital sex ....

Many guys here would wish to own such a great-looking, hand-built work of art. You should start thinking of starting a small scale speaker manufacturing firm ........ serious.

 

[kapvin]

Hi Anil,

TLs are also called quarter wave length speakers.

TL theory from martin j King-define a transmission line loudspeaker as a driver mated to a resonant tube where the natural frequencies and mode shapes of the air in the tube are used to tailor the total system response. This definition does not include any restrictions on the location of the driver in the tube or the boundary conditions at either end of the tube. Also, this definition does not place any requirement on the amount or type of fiber stuffing material that may be placed inside the tube to attenuate the standing waves associated with the tubes natural frequencies.


for a line length of 4ft; that corresponds to 68hz quarterwave if the transmission line is air-filled. now when you stuff it with another substance, say dacron, wool or whatever, the speed of sound changes, therefore the wavelength also changes.

just suppose the speed of sound changes from 332m/s in air to 250m/s in dacron - that would give you 51hz quarterwave .. stuffing with the right material (which slows the speed of sound) can allow you to get away with a smaller line length and still deep bass extension.

I thought you had data on that and I was hoping you'd share. I've searched a bit on the internet on the speed of sound through various mediums, but have not got any good data!

hope that clarifies the question I asked?

thanks for sharing all your info. I'll be follow this thread to see your finished product. just my two pennies worth - mahagony finish would be a great choice..

 

[gobble]

. just my two pennies worth - mahagony finish would be a great choice..

No No ... Make it Orange!! Anything but the personal choice of Anil the creator or his cousin the owner Ultimately to satisfy everyone on this forum, it may end up with Holi colours ... hyeah:

Speaking with nothing more than common sense - The medium of propagation (that matters most) will be mostly air inside the speaker will it not? So you should consider the speed of sound in air. The darcon has the primary function of damping and absorbing resonant frequencies so its interaction will be complex (and incomprehensible) by measurement and weight. Anil is playing it by ear precisely for this reason ... Right?


PS: Changing wavelength will change the frequency - am I missing something here?

Regards

 

[suri]

No No ... Make it Orange!! Anything but the personal choice of Anil the creator or his cousin the owner Ultimately to satisfy everyone on this forum, it may end up with Holi colours ... hyeah:

Speaking with nothing more than common sense - The medium of propagation (that matters most) will be mostly air inside the speaker will it not? So you should consider the speed of sound in air. The darcon has the primary function of damping and absorbing resonant frequencies so its interaction will be complex (and incomprehensible) by measurement and weight. Anil is playing it by ear precisely for this reason ... Right?


PS: Changing wavelength will change the frequency - am I missing something here?

Regards

no,no,non,no-

i demand that anil finish these excellent speakers in Honda (MOTO GP) racing colours -

and i will go to bengaluru to listen and see!

 

[iaudio]

Suri, When ?

 

[suri]

Suri, When ?

july 3rd week?

 

[iaudio]

Fandastik! That would be fine I think, or at the most 4th weekend, 24th...

 

[kapvin]

Speaking with nothing more than common sense - The medium of propagation (that matters most) will be mostly air inside the speaker will it not? So you should consider the speed of sound in air. The darcon has the primary function of damping and absorbing resonant frequencies so its interaction will be complex (and incomprehensible) by measurement and weight. Anil is playing it by ear precisely for this reason ... Right?


PS: Changing wavelength will change the frequency - am I missing something here?

Regards

changing the wavelength will change the frequency?? of course - if the propogation speed remains constant. but the point here is that propogation speed change causes the wave length to change, give the the freq is constant

frequency (hz or per second) x wavelength (m) = velocity of propogation (m/s)


but you cannot change the frequency of an emitted source (unless you count doppler effect.. or interference- but that still does not change the frequency).

I am talking to the speed of sound of sound changing as it moves from one medium to another (And sound needs a medium to propogate) - consequently the wavelength changes.

this idea is used in TL design to use a shorter physical line length while still having the bass extension of theoretically longer line.

i'll be happy to elucidate that perspective via pm

the impression I got from the visuals was that's it's fully stuffed..

 

[Anil kumar]

TL theory from martin j King-define a transmission line loudspeaker as a driver mated to a resonant tube where the natural frequencies and mode shapes of the air in the tube are used to tailor the total system response. This definition does not include any restrictions on the location of the driver in the tube or the boundary conditions at either end of the tube. Also, this definition does not place any requirement on the amount or type of fiber stuffing material that may be placed inside the tube to attenuate the standing waves associated with the tubes natural frequencies.

for a line length of 4ft; that corresponds to 68hz quarterwave if the transmission line is air-filled. now when you stuff it with another substance, say dacron, wool or whatever, the speed of sound changes, therefore the wavelength also changes.

just suppose the speed of sound changes from 332m/s in air to 250m/s in dacron - that would give you 51hz quarterwave .. stuffing with the right material (which slows the speed of sound) can allow you to get away with a smaller line length and still deep bass extension.

Thanks for some gyan on stuffing kapvin, but critical stuffing density can increase effective box volumes up to 30% but we do not need this density for effective damping of the internal mid range sound waves. I had a problem with one of the cabinets, i had stuffed 100 grams more of Dacron that resulted in reduced lower ends ( less bass), so stuffing is critical.

Rahul, Suri & iaudio: thanks for your inputs, i am planning to veneer the cabinets next month. I am working on a new spike design, 3D model is almost ready. It will be a combination of MS & Aluminum.

You are most welcome to audition the new TL's. As they are not mine, i will keep them till the end of July for audition purpose. I have some plans on building SHORT THOR by year end using the same mid bass & Vifa P17 combination. Here the cabinet depth will be 23 inches with additional 2 braces, this cabinet is much tougher to build as it requires 200+ holes :sad:


Regards,
Anil

 

[kapvin]

Thanks for some gyan on stuffing kapvin, but critical stuffing density can increase effective box volumes up to 30% but we do not need this density for effective damping of the internal mid range sound waves. I had a problem with one of the cabinets, i had stuffed 100 grams more of Dacron that resulted in reduced lower ends ( less bass), so stuffing is critical.

that's true for sealed boxes. where a sealed box speaker with no stuffing behaves adiabatically and stuffing makes the system box behave isothermically (And therefore appear larger).

stuffing(preferably lining) in a BR system and Lining in a TL system with absorbtive material works towards absorbing the backwave. I guess that's what you were trying to achieve, but that's a bit different from what I was talking about.

for gyan on lining and stuffing in sealed boxes, here's an interesting resource -

Lungster.Com - excerpts

I would love to hear soundsgreat's midwoofers in another application, so i hope you'll invite me over the next time I am in town.

cheers.

Kapvin

ps - in case you wanted some resources on line length and stuffing, lemme know, i'll send you the stuff via pm

 

[Anil kumar]

Thanks for the link kapvin, please do drop in for a audition when you are in town. I am planning to keep the speakers till July end.



Regards,
Anil

 

[rallynut]

do post pics when they're done,anil.dying to see/hear them.rest assured,will be there in blore with the others to audition :licklips:.cheers

 

[gobble]

changing the wavelength will change the frequency?? of course - if the propogation speed remains constant. but the point here is that propogation speed change causes the wave length to change, give the the freq is constant

frequency (hz or per second) x wavelength (m) = velocity of propogation (m/s)


but you cannot change the frequency of an emitted source (unless you count doppler effect.. or interference- but that still does not change the frequency).

I am talking to the speed of sound of sound changing as it moves from one medium to another (And sound needs a medium to propogate) - consequently the wavelength changes.

this idea is used in TL design to use a shorter physical line length while still having the bass extension of theoretically longer line.

i'll be happy to elucidate that perspective via pm

the impression I got from the visuals was that's it's fully stuffed..

Great thanks! I was thinking very rudimentary physics when I asked. Obviously, it's a little more "kombligated" than that


Sent from my iPod touch

 

[Anil kumar]

Here is the 3D rendered image of the spikes which i am planning.

Anil

 

[murali_n]

Hai Anil,

Congrats for all your hard work and efforts. Pl keep us posted about the performance of the speakers after it burns in.

N.Murali