Considering Transmission Line

[Guiria]

The DIY forum is dead lately so I thought up something to talk about...

Are there generally accepted T/S parameters for TL speaker design? I've done some reading, mostly at Martin King's quarter wave website and I'm thinking about rebuilding my Audax drivers into a TL. I noticed you can buy Martin King's Mathcad TL modeling software for 25 bucks. Has anyone bought and used that with good results? It's something I might try if I can find some kind of 'review' about it outside of Martin King himself.

If I could build boxes and use existing drivers and crossover(if some mods to the xover happened that wouldn't be a big deal) I would seriously consider doing so. It would be a fun project.

I thought about sending TLS a PM but figured someone else might find the discussion interesting.

 

[TLS Guy]

The DIY forum is dead lately so I thought up something to talk about...

Are there generally accepted T/S parameters for TL speaker design? I've done some reading, mostly at Martin King's quarter wave website and I'm thinking about rebuilding my Audax drivers into a TL. I noticed you can buy Martin King's Mathcad TL modeling software for 25 bucks. Has anyone bought and used that with good results? It's something I might try if I can find some kind of 'review' about it outside of Martin King himself.

If I could build boxes and use existing drivers and crossover(if some mods to the xover happened that wouldn't be a big deal) I would seriously consider doing so. It would be a fun project.

I thought about sending TLS a PM but figured someone else might find the discussion interesting.

Good. I helped another member with a successful TL via PM and then Email.

Martin King uses a different TL, what he calls a mass loaded TL. He himself acknowledges the controversy as to whether they are TLs or not. I personally regard them as a variety of coupled cavity reflex, with some features of the Vopight quarter wave pipe.

I have modeled my designs this decade on the model Of G.L. Ausperger published 2000. He had at last published a design CD, which I obtained a few days ago, and I'm starting to play with it. It should speed design considerably.

Now I think your drivers have too low a Qts to be optimal for a TL. For a good TL, you need a low Fs for size of driver, and Qts in the 0.35 to 0.4 range. VAS enters into the equation, as it affect pipe volume Vb. If VAS is large you can have quite a large speaker, it too small you need more drivers to make pipe dimensions practical.

A couple of these SEAS drivers, or these Peerless drivers.

You could use this tweeter with either.

I think you could build a highly cost effective, but very good TL speaker with those drivers.

 

[Guiria]

Good. I helped another member with a successful TL via PM and then Email.

Martin King uses a different TL, what he calls a mass loaded TL. He himself acknowledges the controversy as to whether they are TLs or not. I personally regard them as a variety of coupled cavity reflex, with some features of the Vopight quarter wave pipe.

I have modeled my designs this decade on the model Of G.L. Ausperger published 2000. He had at last published a design CD, which I obtained a few days ago, and I'm starting to play with it. It should speed design considerably.

Now I think your drivers have too low a Qts to be optimal for a TL. For a good TL, you need a low Fs for size of driver, and Qts in the 0.35 to 0.4 range. VAS enters into the equation, as it affect pipe volume Vb. If VAS is large you can have quite a large speaker, it too small you need more drivers to make pipe dimensions practical.

A couple of these SEAS drivers, or these Peerless drivers.

You could use this tweeter with either.

I think you could build a highly cost effective, but very good TL speaker with those drivers.

I've read previous threads here and your blogpost about a modified Thor TL using the Seas Prestige line instead of the Excel. Is that the ideal configuration if using the prestige line for a TL or would you recommend something else?

 

[TLS Guy]

I've read previous threads here and your blogpost about a modified Thor TL using the Seas Prestige line instead of the Excel. Is that the ideal configuration if using the prestige line for a TL or would you recommend something else?

I personally would make it a 2.5 way, and tweak the enclosure a little. The Peerless drivers would make for a cheaper project if budget is tight.

 

[lsiberian]

You've peaked my interest. Those driver prices aren't too shabby either.

I'd love to try a TL and compare it to my insanely sealed speakers when I finish them.

 

[MJK]

Has anyone bought and used that with good results? It's something I might try if I can find some kind of 'review' about it outside of Martin King himself.

If you take a look at Bob Brines' site you will find he uses my MathCad worksheets to model his commercial designs. He has a number of articles on his site that compare measured and calculated SPL response curves. That is probably the best documented independent verification of the worksheets.

I have also compared my worksheet results against Augspurger's program and for the same cases the results match. Augspurger's program is nice but not as sophisitacted as the MathCad worksheets for running a wide range of TL configurations. For example baffle step, floor and wall reflections, and just the physical positions of the driver and terminus are not accounted for in his program.

Hope that helps,

Martin

 

[TLS Guy]

You've peaked my interest. Those driver prices aren't too shabby either.

I'd love to try a TL and compare it to my insanely sealed speakers when I finish them.

I see I have work to do when I get back to Benedict. It will be good chance to get used to my new software.

 

[lsiberian]

I see I have work to do when I get back to Benedict. It will be good chance to get used to my new software.

Well I've not had much time to devote to projects lately either(wedding and honeymoon planning). So there is no rush on my end. I'm pretty satisfied with my current setup. Enough that I've not finished my MBMs and sub yet. I'm actually considering postponing the MBMs and starting the sub project. I feel i'd gain more from it.

Once we get a house I'll have the space to really work. Summer is ending here soon so the temperatures will be good enough to build again.

 

[Guiria]

TLS, seems like you are never home, that is, if Benedict is home

and Isiberian, better get all your DIY stuff done ASAP, that first year of marriage can be a little shaky

I probably have between 2-3 sheets of MDF sitting in my garage, I may have to take up a TL design and order drivers and components down the road. Attempting a DIY tower speaker and finishing it so it looked nice would be quite an accomplishment for me. Since I don't have the drivers and would have to do some saving I think I could build the boxes without feeling rushed to crank them out as fast as possible.

I now have 4 DIY builds under my belt with a couple of 1/2 builds between my brother in law and myself. My finishes are getting better with each build. Perhaps the TL's would be my showcase speaker.

***me, looking into neverland dreaming about a dark wood finish with glossy clearcoat that makes me want to dip my finger into it, and listening to music in my big red chair with my feet up while drinking something refreshing...like an Izze soda, ahhh...***.

Of course I said that about my latest center channel and it turned out pretty good, but not as good as I'd like. I am my worst critic I'm afraid.

 

[lsiberian]

TLS, seems like you are never home, that is, if Benedict is home

and Isiberian, better get all your DIY stuff done ASAP, that first year of marriage can be a little shaky

I probably have between 2-3 sheets of MDF sitting in my garage, I may have to take up a TL design and order drivers and components down the road. Attempting a DIY tower speaker and finishing it so it looked nice would be quite an accomplishment for me. Since I don't have the drivers and would have to do some saving I think I could build the boxes without feeling rushed to crank them out as fast as possible.

I now have 4 DIY builds under my belt with a couple of 1/2 builds between my brother in law and myself. My finishes are getting better with each build. Perhaps the TL's would be my showcase speaker.

***me, looking into neverland dreaming about a dark wood finish with glossy clearcoat that makes me want to dip my finger into it, and listening to music in my big red chair with my feet up while drinking something refreshing...like an Izze soda, ahhh...***.

Of course I said that about my latest center channel and it turned out pretty good, but not as good as I'd like. I am my worst critic I'm afraid.

I'm already married and now can no longer use my kitchen as a workshop.

 

[TLS Guy]

TLS, seems like you are never home, that is, if Benedict is home

and Isiberian, better get all your DIY stuff done ASAP, that first year of marriage can be a little shaky

I probably have between 2-3 sheets of MDF sitting in my garage, I may have to take up a TL design and order drivers and components down the road. Attempting a DIY tower speaker and finishing it so it looked nice would be quite an accomplishment for me. Since I don't have the drivers and would have to do some saving I think I could build the boxes without feeling rushed to crank them out as fast as possible.

I now have 4 DIY builds under my belt with a couple of 1/2 builds between my brother in law and myself. My finishes are getting better with each build. Perhaps the TL's would be my showcase speaker.

***me, looking into neverland dreaming about a dark wood finish with glossy clearcoat that makes me want to dip my finger into it, and listening to music in my big red chair with my feet up while drinking something refreshing...like an Izze soda, ahhh...***.

Of course I said that about my latest center channel and it turned out pretty good, but not as good as I'd like. I am my worst critic I'm afraid.

I'm home, but we have a place at Benedict, and Eagan. My workshops are at Benedict. We travel between the homes fairly often. I'm getting the machinery at Benedict ready for winter now. Ignition tune ups and oil changes.

I will be away for a while in three weeks. I'm doing a trip to the UK to visit my parents at Rochester Kent, my home town.

I'm also off to see my best friend from school on the Isle of Man. He was best man at our wedding. This is how he describes his appointment in the Isle of Man, a post he retired from last October, when he says he finally hung up his wig. He held the post for seven years. He describes it thus.

"Like a medieval bishop, I held several offices in plurality: Clerk of Tynwald, Secretary of the House of Keys, Counsel to the Speaker and Registrar of Members' Interests! The job is a curious combination of law, administration, research and agony uncle, in this tiny but ancient parliament."

The Tynwald is a very ancient institution. The House of Keys is the worlds longest Parliament, having sat without interruption for 1000 years.

I have booked passage from the Port of Heysham, Lancashire, to Douglas, Isle of Man on the Ben-My-Cree, for September 14. I have already received the tickets.

I return to the Twin Cities September 27.

I'm actually planing to build the TLs for our Eagan home.

 

[lsiberian]

I'm home, but we have a place at Benedict, and Eagan. My workshops are at Benedict. We travel between the homes fairly often. I'm getting the machinery at Benedict ready for winter now. Ignition tune ups and oil changes.

I will be away for a while in three weeks. I'm doing a trip to the UK to visit my parents at Rochester Kent, my home town.

I'm also off to see my best friend from school on the Isle of Man. He was best man at our wedding. This is how he describes his appointment in the Isle of Man, a post he retired from last October, when he says he finally hung up his wig. He held the post for seven years. He describes it thus.

"Like a medieval bishop, I held several offices in plurality: Clerk of Tynwald, Secretary of the House of Keys, Counsel to the Speaker and Registrar of Members' Interests! The job is a curious combination of law, administration, research and agony uncle, in this tiny but ancient parliament."

The Tynwald is a very ancient institution. The House of Keys is the worlds longest Parliament, having sat without interruption for 1000 years.

I have booked passage from the Port of Heysham, Lancashire, to Douglas, Isle of Man on the Ben-My-Cree, for September 14. I have already received the tickets.

I return to the Twin Cities September 27.

I'm actually planing to build the TLs for our Eagan home.

Sounds like fun. Eat plenty of Cadbury for me. I love that stuff way too much.

 

[audiofox]

Good. I helped another member with a successful TL via PM and then Email.

Martin King uses a different TL, what he calls a mass loaded TL. He himself acknowledges the controversy as to whether they are TLs or not. I personally regard them as a variety of coupled cavity reflex, with some features of the Vopight quarter wave pipe.

I have modeled my designs this decade on the model Of G.L. Ausperger published 2000. He had at last published a design CD, which I obtained a few days ago, and I'm starting to play with it. It should speed design considerably.

Now I think your drivers have too low a Qts to be optimal for a TL. For a good TL, you need a low Fs for size of driver, and Qts in the 0.35 to 0.4 range. VAS enters into the equation, as it affect pipe volume Vb. If VAS is large you can have quite a large speaker, it too small you need more drivers to make pipe dimensions practical.

A couple of these SEAS drivers, or these Peerless drivers.

You could use this tweeter with either.

I think you could build a highly cost effective, but very good TL speaker with those drivers.

Martin,

I have some extra NHT 1259 12" woofers in my garage. They have a very low Fs (16.5 Hz), Vas is 238 liters and their Qts is 0.445. I think NHT sourced these from Tonegen for their 3.3i with the side firing woofer, which I believe is a sealed enclosure. Any opinion as to their suitability for a TL enclosure?

 

[TLS Guy]

Martin,

I have some extra NHT 1259 12" woofers in my garage. They have a very low Fs (16.5 Hz), Vas is 238 liters and their Qts is 0.445. I think NHT sourced these from Tonegen for their 3.3i with the side firing woofer, which I believe is a sealed enclosure. Any opinion as to their suitability for a TL enclosure?

Sounds as if they could make an awesome TL speaker, but you would need a lot of real estate.

 

[MJK]

I agree with TLS Guy, they will probably require a pretty big enlcosure. You could try putting the driver's T/S parameters into an Excel spreadsheet that is on my site, under the TL theory link, to get some idea of the size required.

 

[audiofox]

Well, maybe the 1259 is not the best driver for a TL enclosure-the spreadsheet produced an effective length of 203 inches. Time to redesign the listening room around the speakers!

 

[TLS Guy]

Well, maybe the 1259 is not the best driver for a TL enclosure-the spreadsheet produced an effective length of 203 inches. Time to redesign the listening room around the speakers!

That's what I do! You are now reaching a satisfactory level of insanity.

 

[audiofox]

That's what I do! You are now reaching a satisfactory level of insanity.

If I fold the 1/4 wave line once, I can fit them in the corners of my HT room-they will still be 8 1/2 feet tall, but think of the bass response!

 

[TLS Guy]

If I fold the 1/4 wave line once, I can fit them in the corners of my HT room-they will still be 8 1/2 feet tall, but think of the bass response!

Now you are getting the hang of it!

 

[Guiria]

Nothing like resurrecting an old thread

I have a pair of the 3" Tang Band Bamboo full range (if you can call them that) drivers WS-1364SA in a ported box tuned around 86 Hz. This was my first speaker build ever. I run them with no crossover and they sound pretty good, although the upper end gets a little harsh when pushed and they are definitely not an spl driver. I find these best to listen to nearfield at low to moderate volume and I really like the natural sound they have.

I came across this article: http://coolcat.dk/bjoern/TABAQ_TL_for_TB.pdf that talks about the TABAQ (TAng BAnd Quarterwave) and thought maybe I should try a TL enclosure for my bamboo drivers.

Of course I have to consult the audio wizards here at audioholics before I embark on any audio adventure. What do you think? I think mostly I'm itching to try something new that doesn't cost any money (or very little!).