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InDIYana 2025 theme announcement, "Tweeterectomy"... but build look-alikes if you want....
Chuck and I conversed recently on what we thought would be good here. Since the premise has dominantly been that of a technical nature rather than aesthetics, we have decided the Tweeterectomy fits very well. We have not really done full-range or widebander themes thus far, and it would be outside the comfort zone of many attendees. However, since they were thought highly of, we would also encourage an aesthetic choice. For those building either a non-competing or competing entry, which means all presented builds, if a famous brands' aesthetics aligns with or without the theme in tow, feel free to build a project that looks like a famous brands' aesthetics. There are many to choose from.
"Tweeterectomy" - no tweeters used, wideband plus woofer in 1.5way arrangement. 3" or larger widebander, must be cascaded style contour network to the 0.5 woofer section. Contours out front are allowed but then affect both or more units, padding on widebander allowed, but no actual electrical highpass on widebander allowed. Multiple woofers allowed, keep gross volume under 1.25ft^3. Insertion point of 0.5 woofer section must occur below 1.0kHz. Yes, this could wreak havoc on impedance with certain choices. I will draw up an example electrical network shortly to clarify any misunderstandings...
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Interesting theme. I look forward to seeing your example network. Any bass alignments for each driver not allowed? OB allowed for the full ranger?
Yeah, I'll need some clarifications. It sound like a conventional 2-way with a wide band non-tweeter is not allowed. Running wide bander with no cap does not sound like a good idea.
2-inchers would have a better chance of filling in the top end. Are single drivers are also excluded? Wide bad drivers need to be sealed or is open back acceptable?
There are, imo, a few really solid 3+ inch full rangers that will carry out towards 20Khz (and beyond) with relatively low fs to run full range with supplemental .5. I've worked with AN 6.5s (and 4s but prefer the 6.5s), and Markaudio. And, allowing a front-end contour network makes the 1.5-way transition. Interesting.
Yes- OB for the wideband is allowed, but if you don't want it flapping in the breeze I would advise against it. Remember that the widebander and the 0.5 woofer share the same initial signal. This means the bass is not filtered out of the widebander.
Different box or cabinet alignments are definitely allowed for the multiple drivers. I foresee this being how the smaller widebanders don't poop their pants. This is why we specified for 3" or larger.
Correct- this is not to have widebanders as tweeters in 2ways. No single driver builds. They must be 1.5way designs. The 1.5way premise is the entire goal.
Woofers and widebanders do not have to be the same drivers. If more than one woofer, then they must be the same.
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Please elaborate on what defines 3" full range. Outside diameter or actual cone. If cone, actual cone, cone + half surround...ect..
Okay, how about we express legitimacy by frame diameter; 90mm diameter and up. This is a normal diameter for those of HiVi 3" for example.
Since next question would likely be 'what if they are not round frames?' Then take the minimum frame spec width, and that has to 90mm or larger. This way the corners/etc are not a factor.
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I dig it! Two areas I've not attempted before. Now I can learn more about the ".5" way setups and try a proper full range driver!
Rules out PC83 with more effective cone area than FE85
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Can we use more than one widebander, as in a line array?
Not this time. Use one, and choose and implement carefully and wisely. Being the box volume requirements, I don't think you can shoehorn in very many anyway.
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I have a pair of PS95-8's that I'd like to use as my widebanders. They pass the 90mm flange test. Will have to find a small woofer to go with them. In terms of internal volumes, can the widebander be mounted in an extremely small subchamber to control excessive cone motion at low frequencies? Or must the windbander and woofer share the same internal volume of air (1.25cu.ft. max)?
I would never suggest 2 different drivers use the same air volume. You can box design as you wish, within the 1.25ft^3 gross dimension.
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I also have some PS95's that I could use but I do not think that I could protect them from thermal damage in this application. They are designed with a very low mass voice coil.
It could be turned into a closed back extended range to limit excursion but that would cause even more heat build up.
Just as long as the voice coil doesn't burn up before the 3 minute house track ends! My pair were red-tag buys at the MWAF tent sale a few years ago, so I would only be out a few bucks if they can't handle the heat.
I might actually end up building something under 50lbs this time...
Diagonal is over the limit. I would assume this would be treated like a truncated frame where you would use the larger size not the smaller.
If you are correct this would kill a lot of drivers, almost all 3-inch "pincushion" frames.
I think the PC105 is better for most applications.
I can already smell smoking brain cells, hear the gears turning, etc....
I can tell this will be a fun one!
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Very compromised designs with no HP filter allowed on the FR. Might have some decent sounding designs... at low SPL levels. Certainly not sota speaker design.
Yeah.. prob'ly right.
Can we horn load the FR driver? Asking for a friend
Sure, it it fits within the 1.25ft^3.
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I told you it was outside of the average builders' comfort zone....
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Choose wisely.... I have faith what I'm thinking about doing will work.
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LOL
So maximum outside volume is 1.25?
There's an old saying, just because you can doesn't mean you should...
What about irregularly shaped enclosures? Does the actual area count? (as in water displacement) Or is it gross height, width, and depth? (as in smallest rectangle box it would fit inside)
Gross volume inside the exterior walls of the enclosure. Bracing, xovers, drivers, ports, PRs, damping, etc all come out of the 1.25ft^3. IE, absolute maximum internal volume if nothing were there but outer shell of cabinet should be 1.25ft^3 or less.
I look at this challenge as something we have not done before. We are trying to get the most out of a full range or wideband driver as possible. This time really not using a xover at all as average xover design methods typically go. This keeps the xover out of the widebander altogether. Limiting the volume of the widebander enclosure will likely be the ticket to keeping its composure since we can't electrically highpass it. How would you accomplish that goal? The woofers take over the BSC duties and the playing low. This is likely to force builders to choose a larger (than 3") or more sensitive widebander to do the deed. Essentially, this is intending the builder to contour the situation by typically abnormal means, and really think outside the box.
Bandpass woofers are allowed, since I've been asked this more than once now... 😁
Just watch your impedance....
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Then that would omit the widebander premise from the get go, and yet, many builders love them worldwide.
Have fun with it! Remember what fun is?🤪🤔
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