Help, Transmission Line Box Specs + Diagram Here, What Driver Should I Use?

[DTMPWR]

Hi Guys,

Following on from the Sub Driver thread that i posted, I have drawn up the dimensions of the exising box i have been using over the past few years.

The driver was reciently damaged and needs to be replaced. I was hoping of you guys can tell me what driver I should buy to replace the damaged one.

The diagrams I have drawn are pretty rough but it does have the internal and external areas of the box, however it doesn’t take into account things like rounding of the internal corners or dampening material.

Suitable drivers have a fairly high Qms (3 to 6), a fairly low Qes (0.30 to 0.40) and a correspondingly low Qts (0.30 - 0.40).

Sub Box Diagram

Thanks in advance,

Adam

[norpus]

Hi Guys,

Following on from the Sub Driver thread that i posted, I have drawn up the dimensions of the box and was hoping of you guys can tell me what driver I should use.

The diagrams I have drawn are pretty rough but it does have the internal and external areas of the box, however it doesn’t take into account things like rounding of the internal corners or dampening material.

Suitable drivers have a fairly high Qms (3 to 6), a fairly low Qes (0.30 to 0.40) and a correspondingly low Qts (0.30 - 0.40).

Sub Box Diagram

Thanks in advance,

Adam

Why these TS parameter ranges exactly DTMPWR? Is that from the original designer or from say specs on the Tumult 12?

How much leeway have we got or are you locked in?

What amplification do you have to drive?

Is this for HT only or music also?

If mainly music, what type?

What SPL levels are you looking for at X mtrs at listening position in Y m3 of room?

[betty boop]

this thread herre has some good info

http://www.planetaudio.com.au/forum/index.php?showtopic=2067

[DTMPWR]

Why these TS parameter ranges exactly DTMPWR? Is that from the original designer or from say specs on the Tumult 12?

How much leeway have we got or are you locked in?

What amplification do you have to drive?

Is this for HT only or music also?

If mainly music, what type?

What SPL levels are you looking for at X mtrs at listening position in Y m3 of room?

Norpus, this is my exising box so this is why i am using these dimentions

There is a bit of leeway there, it doesnt have to be perfect it only for HT use.

I have the 350W jaycar amp in it, there top of the line model the one with the remote control.

100% for HT.

And i dont know the answer to this but i really like a lot of bass

[Tweet]

Why do you want to build a TL subwoofer ? They are not a very efficient design.Here is some background on the technicalities involved.........

http://www.t-linespeakers.org/design/MJK-f...mies/index.html

A good Bass Reflex design is difficult enough let alone the hassles of constructing a 'proper ' transmission line for a particular driver.

Note that the typical T/S parameters of a driver are just ballpark figures as individual drivers can be wide of the mark in spec., so unless you can measure its actual characteristics you will not be able to optimize the box or T/L with the driver, especially for the higher power levels.

Better to use a proven design than a roll-your-own if you can.

C.M

[DTMPWR]

Guys this is an exising box, I built it around 8 years ago, the woofer in it was reciently damaged and needs to be replaced.

The design came out of a book, they are the dimentions the box had.

All i need is help finding a replacement driver to work with the paramaters of the box i have given.

[Tweet]

Guys this is an exising box, I built it around 8 years ago, the woofer in it was reciently damaged and needs to be replaced.

The design came out of a book, they are the dimentions the box had.

All i need is help finding a replacement driver to work with the paramaters of the box i have given.

Sorry DTMPWR,

Do you have the Brand name, driver model, anything that might point us in the right direction ?

The problem is loudspeaker drivers are like tires, the greater majority all look much alike, they all work but don't perform equally well under any given circumstance, so trying to match a cabinet design to a loudspeaker driver often leads to disappointing results.

It will be a hit or miss affair I'm afraid.

C.M

[DTMPWR]

Sorry DTMPWR,

Do you have the Brand name, driver model, anything that might point us in the right direction ?

The problem is loudspeaker drivers are like tires, the greater majority all look much alike, they all work but don't perform equally well under any given circumstance so trying to match a cabinet design to a loudspeaker driver often leads to disappointing results.

It will be a hit or miss affair I'm afraid.

C.M

Unfortunatly i dont have any info, the old driver was not really matched.

I was under the impression that if you had the box dimentions, area etc, then you can find a driver to suit.

I thought we where able to go through these lists and find the most sutiabe driver, if we found something with the right FS, Qms, Qes, & QTS, then it would be a match for my enclosure.

List 1

List 2

[Tweet]

Unfortunatly i dont have any info, the old driver was not really matched.

I was under the impression that if you had the box dimentions, area etc, then you can find a driver to suit.

I thought we where able to go through these lists and find the most sutiabe driver, if we found something with the right FS, Qms, Qes, & QTS, then it would be a match for my enclosure.

List 1

List 2

Loudspeaker design all comes down to juggling a whole of set of compromises in driver parameters and cabinet loading, maximum SPL's ,bandwidth, damping etc...etc ...etc.

If the Jaycar driver appears to be relatively close to what you need then that may meet your needs.

Keep in mind though that (from personal experience) such drivers are generally out of spec. with published data. Quality control with the cheaper Asian imports tend to be around the + 20% mark of published data.

If you cannot measure the parameters of the driver (after a run-in period ) you'll have to take data at face value.

An infinite baffle (closed box) design is much more forgiving of variant driver parameters than Bass Reflex or T/L so as an interim measure, closing off the port would provide this and give a less compromised cabinet for the driver.

Unfortunately loudspeakers need to be designed from the ground up to get the performance one hopes and requires a lot of tweaking and patience to even come close.

C.M

[DTMPWR]

[Tweet]

I did a quick calculation on the internal volume of your cabinet, 167.8 litres - volume of bracing and duct material.

That's a BIG box.

I just checked an old Jaycar catalogue (2004) the 12 " carbon fibre driver (cs 2246) would work in a 95 -100 litre bass reflex design.

Reducing the internal volume of your cabinet to 100 litres and using the recommended port diameter (pipe) 85mm diameter/137mm long should give you good results

Tuning with large box volumes is very broad and a few millimetres either way won't make any difference audibly.

That's possibly your cheapest outcome though it isn't quite what you wanted, but for HT it's largely booms and bangs anyway that is handled by the subwoofer.

C.M

[DTMPWR]

I did a quick calculation on the internal volume of your cabinet, 167.8 litres - volume of bracing and duct material.

That's a BIG box.

I just checked an old Jaycar catalogue (2004) the 12 " carbon fibre driver (cs 2246) would work in a 95 -100 litre bass reflex design.

Reducing the internal volume of your cabinet to 100 litres and using the recommended port diameter (pipe) 85mm diameter/137mm long should give you good results

Tuning with large box volumes is very broad and a few millimetres either way won't make any difference audibly.

That's possibly your cheapest outcome though it isn't quite what you wanted, but for HT it's largely booms and bangs anyway that is handled by the subwoofer.

C.M

I just called Jaycar thats mode is discontinued.

This is the replacement model New Jaycar Sub

Yes the box is massive its about the size of a wheely garbage bin.

How about a car sub? there are 1000's of them on the market.

This is so annoying why does it have to be so hard

[RodN]

In essence you are trying to find a driver for a TL design where one would normally create a TL enclosure for a specific driver.

[Tweet]

I just called Jaycar thats mode is discontinued.

This is the replacement model New Jaycar Sub

Yes the box is massive its about the size of a wheely garbage bin.

How about a car sub? there are 1000's of them on the market.

This is so annoying why does it have to be so hard

I just looked at the T/S parameters and noted in the text......

" Thiele Small Parameters (measured with voice coils in parallel) "

I had a look through the Jaycar site and to be honest what they stock now is really just rubbish speakers.

The only subwoofer driver I had bought from them was the 12" Response 'Precision' driver (double magnet/dual voice coil) for $289 but I notice they don't stock that anymore, it was quite effective in a 100litre B/R design , but as I say Jaycar are only stocking Asian 'junk' at the moment.

Personally, I would go for one of the Peerless XLS drivers in a cabinet recommended by them (saves a lot of frustration) , the cabinet suggestions are usually associated with the driver specs.

You might like to look at this ...if you like your bass.

http://www.geocities.com/adrian_mack/

C.M

[CAVX]

In essence you are trying to find a driver for a TL design where one would normally create a TL enclosure for a specific driver.

Yes a real spin on "reverse engineering"...

Mark

[byte-me]

This one might come close.

TIW 300 Ohm 12"

[DTMPWR]

I have made my mind up.

I have just bought the 12" dual voice coil sub from Jaycar was $150, on my trade account. This will get me by for HT use for the next month or so.

Then i am going to buy a 12" Tumult once they are back in stock, probably around march & build a box around that.

This long weekend i am going to be doing a lot of work to my HT room, have a new JP coming, new Speakers & have to get the sub going again.

Will get up some pics next week.

Thanks for everyones time, i will let you know how i go with the Tumult when they are back in stock.

Adam

[RodN]

I have made my mind up.

I have just bought the 12" dual voice coil sub from Jaycar was $150, on my trade account. This will get me by for HT use for the next month or so.

Then i am going to buy a 12" Tumult once they are back in stock, probably around march & build a box around that.

This long weekend i am going to be doing a lot of work to my HT room, have a new JP coming, new Speakers & have to get the sub going again.

Will get up some pics next week.

Thanks for everyones time, i will let you know how i go with the Tumult when they are back in stock.

Adam

Sounds like a great project Adam, I look forward to hearing of your progress.