Design: Help!

acesand8s

Member
2020-02-18 7:56 pm
{lol} Using a Peerless 6.5" Aluminum HDS series woofer, and 1" Copper/Beryllium tweeter from China, "DavidLouis". I want help to design a transmission line tower and the crossover, I have a Linkwitz-Riley 12dB/octave @2300 Hz chosen, with 8.2 uF in series with the tweeter, .60 mH across it, and .80 mH in series with the woofer, 6.2 uF across it. The woofer is 8 ohms nominal and the tweeter is 6 ohms nominal. The woofer has a really good low-end extension for a 6.5" and the sensitivity of the tweeter is about 5 or 6 decibels higher at the test point, on the spec sheets. Can someone on the forum contact me to address this build? I don't have the software to fine-tune the crossover, nor do I have a box designer, but I'm going to design a transmission line tower, with front-firing woofer and front-firing tweeter closely placed.

I can provide further information if you can help. Building with 19 mm MDF from Home Depot, and maybe using some 12 mm MDF as well. All glue joints, and cleat and clamp methodology. No screws, except to mount the drivers and the terminal plate and crossover board.

I'm a build amateur, since 1979, and need design help with the crossover.
I hope someone will respond. Using 20 gauge air-core inductors. I could spend more and use 14 gauge. The .8mH choke is .64 ohms with 20 gauge and .22 ohms DCR with 14 gauge. I'm thinking 14 gauge for the low pass section, 20 gauge for the high pass section.
 

AllenB

Moderator
Paid Member
2008-10-18 11:31 am
You might look for the Augspurger transmission line alignment tables.

You might consider and discuss the shape and size of the baffle around or in front of the drivers.

There are a number of good crossover simulators, some written by members here such as Xsim, and Vituixcad. Search here for those.

You could also post links to details on the drivers.
 
No screws, except to mount the drivers and the terminal plate and crossover board.
No screws but bolts and nuts like the one pictured.
Crossover board is better kept outside the enclosure.
Terminal plate is another useless thing, once the crossover is OUT and all the electrical joints are reduced to minimum.

About the crossover thingy, I'd keep the HP part for the tweeter which seems " ad hoc" and try some bigger inductor for the woofer. Also L-pad for the tweeter, of course!
 

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If you are going to design your own speakers you need to invest in the tools that are required. That includes crossover design software, box design software, a microphone, and analysis software such as REW. A lot of very good software is free, but you'll have to buy the microphone. And then you are going to have to spend time, lots of it probably, learning how to use everything.

To expect others to do all of this for you is asking a lot of other people, although there are a few here who might provide some amount of help. But you'll never get it right if you can't design, test, analyze, and tweak things yourself. To expect others to do that remotely for you is unrealistic.

And designing your own speakers is fine if you are not in a hurry for very good sound quality and are willing to make the time and money investment. But if you want to have something to enjoy right away consider building a kit designed, tested, and refined by one of the experts.

If you insist on a transmission line speaker then your best bet is to buy a kit with one of Curt Campbell’s designs. There are three to choose from depending on how much money you want to spend.

TriTrix is the least expensive from Parts Express, and they even offer an MDF enclosure kit with all precut parts.

Next up is the Campbell’s Invictus from Meniscus Audio using a Scanspeak 7” woofer and CSS Tweeter in a transmission line enclosure.

And if you like the idea of a 6” woofer with a 1” tweeter in a transmission line enclosure, then consider the MoreTrix 2-way speaker kit designed by Curt Campbell and using excellent Morel drivers. It is offered by Madisound.

The chances of you achieving a speaker with sound quality even close to any of these transmission line designs as a first time builder are very small.
 
...and nuts like the one pictured.

818260d1582106757-design-help-ragno-jpg


i do not like these. I currently have 7 (of 8) KEF B200s marooned in their box because the t-Niuts have pushed out and are just spinning.

This seems to happen fairly often.

Threaded inserts acomplish the same thing but have less issues as far as failing.

dave
 

acesand8s

Member
2020-02-18 7:56 pm
If you are going to design your own speakers you need to invest in the tools that are required. That includes crossover design software, box design software, a microphone, and analysis software such as REW. A lot of very good software is free, but you'll have to buy the microphone. And then you are going to have to spend time, lots of it probably, learning how to use everything.

<snip>


You don't have to tell me this...I know I am asking for help...you're a pretty severe person...maybe yoga?
 
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... a Peerless 6.5" Aluminum HDS series woofer…

Looks OK for a TL if this is the one https://www.parts-express.com/pedocs/specs/264-1086--tymphany-hds-p835025-spec-sheet.pdf

Augspurger & Martin King brought proper TL modeling to use, using 2 different modeling analogies, that argreed very well. Martin actually continued developing his models. The MJK website is a wealth of info on modern TLs.

MJK has alignment tables, but they only handle the simpliest of TLs. Leonard’s TL modeler and HornResp (do use damping in your model) do good jobs of simmming, unfortunately the MJK modeler is NLA.

Building with 19 mm MDF from Home Depot, and maybe using some 12 mm MDF as well.

You can’t find good plywood? Althou popular (because it is cheap) MDF is not a great speaker building material.

dave
 
You don't have to tell me this...I know I am asking for help...you're a pretty severe person...maybe yoga?

Apparently you think that my comments were severe, but I hope you realize that I was really trying to help you.

It's been over a week since your original post and there have been no responses to any of your requests for help. So again I would like to point out that you are asking for too much.

If you can narrow your questions down to things more specific and focused you might still get some help.

If you really insist on pursuing a transmission line enclosure, which is a difficult design, then I suggest a post just on that topic and at least include in it the T/S parameters of the driver you want to use. Someone then might give you a response. But there aren't many good modeling tools readily available for TL enclosures, so you still may not hear from anyone.

And leave the crossover issue out of it for now. Consider making that a separate post also and again include the driver's performance parameters.

You need to give people more information, a better starting point, and a more focused request. That might get you some responses.
 
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