Yet another IDS-25 clone?

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I've just kinda turned into a old guy whose mellon gets tired and wants to know "what works? .... what matters most, and in what order?" LoL

I have always been that guy. It can be frustrating trying to find what should be very basic info in that regard (what works, matters most) on so many topics. Who's got time to reinvent the wheel with every project??? I have too many hobbies and interests to figure everything out from scratch...

The internet has been such a boon towards broadening what is possible for amateurs and hobbyists to learn and know things with a relatively short time frame of R&D/experimentation invested. I remember being a kid and having to dig up info at the library, and pray you could find some knowledgeable, more experienced person to help explain the things that didn't make sense no matter how many times you read about them.

Very grateful for forums like this where people can bounce ideas off of one another and learn from the successes and failures of others, along with hopefully helping others in the same way.
 
If you want to know how the inside works out, a simple impedance sweep tells us a lot. The TC9 impedance is pretty clean. So if the sweep of drivers in enclosure shows some weird bumps, you'd have internal resonances. Even a small bump like that can result in dips in the frequency response. Easy enough to check.

I guess I've got some more reading to do :) and maybe I'd better dig my HP audio generator out of storage and check that it is in prime shape. I either dug it out of a dumpster in high school or bought it at a surplus store. Long time ago when nobody cared to save such things, but it looked nice, so I rescued it. Glad to finally have a reason to have hoarded - er, I mean collected it. I could probably do with the computer, but I don't have any sort of sound card options to work with, just a giant iMac at work.

This looks pretty straight forward: Loudspeaker impedance measurement using a multimeter and 2 resistors

If anyone has other tips about how to get this done, let me know! I was wondering where everyone is collecting their data on the speakers. Somewhere I have some (I think) decent condenser mics, and my EQ on the stereo at home has a pink noise generator and a tiny display that shows 20 or 30dB of levels across the audio spectrum. I've always used that to trim the EQ on my system close enough that it reads flat, and it tends to sound like balanced tonal spectrum when listening to music.
 
If anyone has other tips about how to get this done, let me know! I was wondering where everyone is collecting their data on the speakers. Somewhere I have some (I think) decent condenser mics, and my EQ on the stereo at home has a pink noise generator and a tiny display that shows 20 or 30dB of levels across the audio spectrum. I've always used that to trim the EQ on my system close enough that it reads flat, and it tends to sound like balanced tonal spectrum when listening to music.

Impedance measurement is quite simple with REW (Room EQ Wizard) Free software works on a Mac and the onboard sound should be fine if there is a line in.

Impedance Measurement

A calibrated measurement mic like the MiniDSP UMIK is a good investment and really quite cheap, it works via USB so no sound card needed.

Unless the condenser mic is calibrated it is not really that much use unless you can borrow a calibrated mic to calibrate it against!

The EQ can be dialled in by ear, I got pretty close to my design target by tweaking parametric EQ in realtime but the measurement mic really helps to know what you actually have.

REW really is a gift to anyone interested in DIY audio.
 
I tried to stay as narrow as i could too, just because 'why not?'
And i at least managed a 1/4" roundover on the edges.
Beyond that seemed impractical to chase for my goals.

And honestly, I'm glad I didn't try to do more there.
From experimentation so far, I think driver size and spacing have one or more orders of magnitude more impact, than potential diffraction issues.

But don't let me be a downer when it comes to overthinking...it can sure be fun, huh?:)

I've just kinda turned into a old guy whose mellon gets tired and wants to know "what works? .... what matters most, and in what order?" LoL

Sorry Mark, to (mis)quote you here...

Think about what happens out in the room. Diffraction is a cause of a secondary sound source. It's effect won't be exactly equal if you move around in the room. So we can't EQ it away. The more you can avoid it, the better it will be. There's no point in comparing it to other compromises. Just look at everything separately and try to get the best result.

If we start with: the driver spacing will probably be "more orders of magnitude more impact" we can neglect a lot more, should we really? Even if it is relatively simple to avoid? Control what you can, let go of the part you can't control. That would be my advise.

Fill a tub with water, tab your finger on the water to make waves. Create some disruption at an edge and tab again, observe what happens... Or just simply use something like Hornresp to simulate it :D.

I see a lot of denial about the effects diffraction on this forum. Statements like "I can't hear it..." It probably has no big influence, etc.
You know what? Things like diffraction of speakers can lead our listening brain back to the source of the sound. If you want your speaker to disappear, avoiding diffraction is one of the helpful tools to get there. Even if you don't make a mental note while listening to your speakers, saying to yourself: I can't hear anything. But the brain will be smarter, it's trained to be. It will analyze the sound and it's source and will point you at the speaker.
This part we don't "think" about, but it does work. Same goes for early reflections, they work very similar. We are a lot smarter than we think, we are always "measuring up our environment". Without thinking about it! How cool is that!
Just saying...

Me, I'm interested in "fooling our brain". So I keep focused on these tiny details.
 
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Hi Ron, I'm not saying ignore diffraction...not by any means.
I was just saying to Anchorman, given the debate he has been having with himself about how deep to get into his initial cabinet design (for example post#8),
....that there are bigger fish for him to fry right now, than diffraction.

That said, it is pretty clear you and i have different approaches. I try lots of things in lots of locations. I've built nearly 25 boxes in the last three years, because of different objectives.
Don't really have the desire to optimize details that don't seem to present a problem.
I'm always asking myself, what is the biggest issue I need to address....that's my idea of optimization.
If I ever do get to the point diffraction is the biggest, I've won :D
Of course, I do try to adhere to all the common sense advice to be found on the forums regarding good practices....it was actually a real pain to engineer a way to have even a 1/4" round over on the driver baffles, in a way that could work with both the cbt and straight box...but I did it :)

BTW, yes, couldn't work without impedance plots...the one below is all 24 drivers in the straight box together, a little higher in freq than i hoped
 

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Impedance plot looks good! No problems there.

Every design can be improved on, no matter what you start with. It is the mechanisms we as humans recognize our environment with, that points to diffraction playing a role in that.
Just try it, on any design that shows potential. Improve it by improving the diffraction avoidance and listen again. Throw in some cross talk avoidance and things get even more interesting.

How would you know what role diffraction plays, if you don't make it the only variable at play or "devise under test". This whole Stereo game is based to our two ears and our ability to use a few different mechanisms that allows us to recognise and place that sound, once you start playing with those mechanisms, you can even "adjust" them to suit your taste.

I'd say the biggest hurdle is your own brain and how it functions. No no no, I'm not solo-ing you out here :D. As long as we have 2 ears and a brain in the middle, that's the part that needs to be satisfied. Yes, our bone structure, in fact our body works with it too, as do our eyes, which can be pretty deceiving.
The more you start playing with the different mechanisms our brain uses to "identify our world", the more powerful the presentation of the music can become.
You,as well as me, have already concluded phase (or timing) being important. Well, diffraction creates partial copies that arrive slightly later than the main sound: not a good thing.
The whole cross talk between our ears is a pretty big disturbance too, however most people simply ignore that. But that does not mean it is not happening. An observant listener can check this easily.

Even the perfect speaker, as far as measurements go, does not solve that part.
 
This whole Stereo game .........

Aaah, here is another area of different objectives...

I prefer mono about equally with stereo....never know, depends on the tune.

I feel source material varies so much, that a mono-vs-stereo test is a necessary starter to get the most from a song.

And it also varies so much that I have separate level controls for each driver section for tonal control while maintaining linear phase, as spoken of before....

I know probably not many people agree with such practices.

But to me, those are big picture details that continually make a huge difference in how well i enjoy a particular tune....
and imho make much more of a difference than many of the details commonly given attention.
 
If you're concentrated on a perfect speaker, it will do much better in mono.
Get the stereo principle in play with all it's quirks, adjust for that and more and more songs fall into place, I promise.

All it means you are getting a different balance than you're supposed to get.
Most of the people mixing, mastering this stuff do know their job. If it sounds good in mono, it can sound good in Stereo. But good mono performance is the ultimate test of a speaker. Stereo includes way to many variables.

Mono is missing out, for what i like though. I just like it too much, so I've spend more time understanding it's principles.
First goal was to get as good a phantom center (in balance) as it sounds in mono.
Getting both center and sides well balanced is a whole different ballgame. It won't happen accidentally.

I'm not a mono or stereo aficionado. I just love music and want to hear the stuff I like the best i can. :)
 
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If you're concentrated on a perfect speaker, it will do much better in mono.
Get the stereo principle in play with all it's quirks, adjust to that and more and more songs fall into place, I promise.

All it means you are getting a different balance than you're supposed to get.
Most of the people mixing, mastering this stuff do know their job. If it sounds good in mono, it can sound good in Stereo. But good mono performance is the ultimate test of a speaker. Stereo includes way to many variables.

Mono is missing out, for what i like.

Yes, easy to agree that good mono is the test for a perfect speaker.

I'm quite sure I'm getting the balance I'm supposed to get... I've run literally thousands of transfer functions over the last few years, and have very accurate prosound boxes for comparative evaluations.

It is as you say,... more songs fall together the better a speaker is tuned, particularly in mono.
That's one of my main judgement criteria, past listening and measuring.

But i find the correlation between excellent speaker tuning, and songs falling together, weakens substantially in stereo.
However, when stereo is right, it's awesome.

The mixing, mastering folks may know their stuff, but you have to admit...source material varies greatly. It's nice to be able to override them. :)
 
I'm quite sure I'm getting the balance I'm supposed to get... I've run literally thousands of transfer functions over the last few years, and have very accurate prosound boxes for comparative evaluations.

I'm not questioning those speakers, I'm questioning what you really get, at your ear. Even outside without a room, it should even be more clear to hear under those circumstances.
 
OK you asked for it LoL....
Some good point sources might change your mind again ;)

Why? Because you question the effectivity of line arrays based on the half tests you have run so far? :D
You haven't even started unlocking their potential! That part I am serious about. There is much more to have than what you've heard them do so far.
I'm not new to point sources you know... I've heard other speakers too ;).

This has nothing, absolutely nothing to do with point sources or line arrays.

Try some ambiophonics, do it outside with your favorite point sources. Try a few different race algorithms. One of them just might show you what's there, potentially ready to be unlocked. The speakers will be placed close together for such an exercise, that alone should be a worthy first advantage.

Not that I would want to run ambiophonics, I'd hate the tought of having to sit behind each other to get to listen with the best benefits (lol). But I have played with it, extensively. (with point sources :eek:)
It did not bring me what I wanted, but one thing it did do was to show it's potential. Now I try and do the same with a Stereo setup, which means all processing needs to be adapted to that.

Whatever speaker we use, get it to behave at the listening spot as they should, and they will sound more alike than different. If that's done well, you simply forget about the speakers completely, and all that is left is music.
 
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You're right, it is much more clear outside. Almost discouragingly so....

THAT is what I'm talking about. :) And it need not be!
(although we could be talking way past each other, making up an entirely different meaning of what is typed here)

P.S. we should move this discussion. We are a guest on this thread. We could continue on my thread, I don't mind a little light blabber :D

My apologies to the OP :eek:
 
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Thanks for your continued enthusiasm and comments...
I don't mean to sound unresponsive, but it's hard for me to convey how much I don't want to be confined to a listening spot, or work to make one the primary focus.
Part of the joy of outside music for me, apart from the overarching sound quality, is being able to play/party/lounge in a wide area with a bunch of friends.
Back to different objectives I guess :) I like hi-fi PA..

Anyway, it's probably time to move on...i feel bad so off topic from Anchorman's thread...thx again
 
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My sample drivers showed up in the mail yesterday, a little sooner than I had expected! I guess I’d better get cracking at making some test boxes. I was kind of surprised just how tiny they are. I had gotten to thinking exclusively about the big sound that these will make in pairs of 25, and so seeing just a couple of them in a box was a shock.

I’ve got my eye on an oscilloscope/network analyzer/waveform generator that can hook up via USB, and will do the graphing for me, then just need to get the microphone for frequency measurements sorted out.

I made some headway regarding how I might make something more than a plain box that I can still cut the pieces on the router, while also avoiding stack type construction. Even MDF and particle board expand and contract significantly more in thickness than in width and length with basic humidity changes. It’s mostly because they are short wood fibers essentially formed into a mat, so even though across the panel the grain seems random, in thickness the grains are still relatively planar/parallel to one another. One place I read something like 5% dimensional change, which almost seems excessive until you think about the garbage wood that gets used to make them. The best figure I’ve read about for wood is 1/8” per foot, which you get with Honduran mahogany and a few others. Most oak is closer to 1/4” or foot, and most pines are worse from there. As you look at the grain from the end radiating out from the center of the tree gives a different figure than looking at how it expands across the direction of the rings. Along its length almost no change with moisture.

Once I get a little further along, i’ll Post pics of some cad renderings. The program I use is evolved from autocad’s inventor, so look for some tall speakers sitting in the same field that wesayso used for his renderings :)
 
Get the Peerless TC9FD18-08 and not the Dayton PC83-8. I bought 10 of the Dayton PC83-8 full range drivers when they were first introduced because they had a larger magnet. The frequency response shown seemed ideal but none of the 10 were even close to that. There is extreme breakup in the top octave on some and big dip on others. I have a test setup on a very large baffle using a pair of the PC83-8 and another pair of the TC9FD18-08 wired in series parallel to give an 8 ohm mono load. I chose the best ones of each driver to blend together. The result is smooth powerful sound you would not believe. If you sit close to an array you will hear the comb filtering that does not sound very good; however, if you bounce that sound off an angled wall and listen many feet away the sound is fantastic. Like the organ is in your room. The combined power rating is 120 watts. Efficiency is high.
 
That’s the thing, isn’t it? I hadn’t considered consistency of product yet. I was more looking at the specs they publish... I’ll hopefully have a way to make some decent measurements soon enough, along with using the measuring devices mounted on either side of my head.
 
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