Yet another IDS-25 clone?

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Just snagged a syscomp usb oscilloscope/network analyzer from eVilBay for $30, supposed to be new. Looks like it should be easy to make impedance measurements/graphs with it, and hopefully will have some other uses too. It’s only got a useful range of 200khz, but should be good for audio related testing.
 
Making progress: got my impedance measuring setup working, it just needs a few tweaks to the leads in order to simplify and speed up connections. Almost time to start building some test boxes. :)

Hopefully Wednesday I get a Harmon kardon 100w amp to play with also, which will get me closer to having more than enough power to drive these speakers in my listening space. It is yet another project that needs work, but hopefully it will be an easy fix.
 
Well, I just bit the bullet and ordered 50 tc9 drivers from Madisound. Comes in at less than $400, which leaves some cash in the subwoofer budget. I was looking hard at some of them from mark audio that seemed to have pretty flat response curves in the upper range and nice reviews, but I don’t have it in me right now to make this into a thousands of dollars project!


I’ve spent a fair bit of time distracting myself with thoughts of other speakers, but I’m not going to be satisfied until I hear these, and it’s cheaper and faster to build them than to drop by in the Netherlands in the middle of a pandemic. :)

Now I need to hurry up and finish the box design before these drivers show up! At the moment I’m looking at baffle made up of either 12mm BB plywood, or from a lamination of particle board and masonite. It looks like the smart move is to mount the speakers from the front, which will make it easier to seal the entire box. Gasket material is then an issue, but I can cut pieces with a laser cutter from rubber sheet or from rubber cork sheet. I’m tempted to mount the speakers from the inside, but that means making the entire baffle removable, which doesn’t seem cut a good idea.

I had come up with a way to build the cabinets into a shape slightly more interesting to look at than a plain box, but there’s a part of me wants to make them disappear into the background as much as possible, and nothing does that quite as well as a boring box painted to match the walls.

More to come soon.
 
When I did my line arrays, I got two extra drivers, just in case.

Nothing more infuriating than starting the whole build to find a driver or two damaged or assembled poorly.

If all checks out, you'd still have an extra pair for surround duty or a small little system somewhere else or to give as present.
 
Well, I just bit the bullet and ordered 50 tc9 drivers from Madisound.

Funny, I am at almost the exact same stage as you. I picked up some eval units a while back and my Madisound order went out a couple days ago. :D

I started a build thread: (YAPLA - Yet Another Peerless Line Array) but haven't added anything to it yet.

Like you, I've been running through some cabinet designs. One thing to consider if you are still interested in rear mounting the drivers is to make the front baffle fixed and use a removable rear panel. You would need to pay attention to the layout of any internal bracing, but you may be able to make it work.

Good luck,

-bill
 
I had this brilliant idea to make the columns out of 6” SDR 35 pvc sewer pipe. Unfortunately this leaves things a little bit too small inside. Would probably be great for a different driver, and 10 foot sections are only $35 plus tax at the big blue home improvement store. Tomorrow I’ll be calling the local plumbing supply to see if they have anything larger for a reasonable price. If not, it’s back to making these out of wood, which makes making things round much more difficult. I had initially thought to stack the way Wesayso did his, but I did the math before I even saw his thread, and realized that Birch ply, MDF, and most other materials are a lot less stable than people think. Over the 7-1/2 feet, it’s 1/4 or more of expansion and contraction. Could work if I made the cuts for the drivers in the edge grain of the material, but this is less than ideal and a lot of extra work.

Fiberglass over foam is an option, but I kind of hate working with fiberglass. If 8” PVC pipe is not a viable option, I’ll try doing longitudinal cuts in the plywood so that it can bend into the shape I want, and if not, I’ll accept defeat and build a simple wooden box.
 
Getting back to baffle design for a more rectangular box, how big of a round-over is good? I suppose anything is better than nothing, but is there a point of diminishing returns on this? I’ve been reading about baffle sizes, and there doesn’t seem to be much good in going wide, unless I go really wide. Beaming from the driver is going to prevent the high frequencies from benefitting much from a wider baffle, and on the bottom end, the efficiency gains of multiple drivers help already.
 
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