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.