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4thtry's InDIYana 2025 theme prototype
This will be a simple 1.5 way in a small 0.26 cu. ft. sealed box. Drivers will be the Dayton PS95-8 and the TB W6-1139SIF. A padding resistor will go directly on the PS95-8. A cascaded HF contour will also go on the PS95-8 as well as the woofer. A big inductor/cap combo will go on the woofer in an attempt to achieve a flat 500Hz baffle step blend.
The boxes are glued up and I'm currently in the process of gluing foam padding to the entire outside of each box. A 3" to 1.5" PVC adapter will be used as the enclosure for the widebanders. Tomorrow I should be ready to take measurements. I'm going to give these the full 360 degree horizontal and vertical spinorama treatment. The box is small and will be very easy to clamp and flip sideways to take all the needed measurements. It will be interesting to see what kind of directivity match (or mismatch) I will be able to achieve with this driver/box combo. Stay tuned.
Comments
Quote from Wolf's initial post:
"Contours out front are allowed but then affect both or more units, padding on widebander allowed, but no actual electrical highpass on widebander allowed."
I think he is referencing using a notch of some kind, as he calls it a contour filter. Might be splitting hairs at this point.
Edited initial post, which was poor worded on my part. I am well aware of the rules.
I'm glad you made the error in wording, I think what I had planned in my head was not within the rules.
Not trying to bust you out. Just the way it read I felt I should bring it up so that you didn't spend a lot of time on a project and find out the day of the demo that it didn't meet the criteria. I know I was a bit confused with the rules until Ben clarified them and gave my conceptual xo design the ok.
All good. I think this is definitely one of those situations where almost anyone could misinterpret the rules. I am pretty sure I understand the rule you quoted. Going forward, I think I need to get my xover model set up in VituixCAD first to see what I can come up with. Then I will probably have additional questions for Ben. Rules are rules, but sometimes I like to bend the rules, if I can get away with it.
I'm glad you get to wear the rule bender collar as I was the worse for the longest time
It's not a collar, it's a crown!
Gluing the PVC enclosure in place. Notice that I am placing the 3" diameter PVC adapter slightly off center of the PS95-8 driver cutout. This was done to distribute internal reflections around somewhat. Same concept as not putting a driver directly in the center of a small, round baffle, which is the worst thing you can do. The cap on the back will not be glued. I want to add a 1.5" PVC splitter later on for dual chamber experiments.
Edit: I should add, when I get done experimenting, I will be adding a top box cover over the top of the PVC pipes and/or whatever pipes or dual chambers I have going on the top side. The total volume will be within the 1.25 cu.ft. limit, with 0.26 cu. ft. being eaten up by the woofer and the remaining 1 cu. ft. being used by the widebanders experimental chamber system. But the first experiment will be to load the widebander into a very small sealed enclosure and give it a power handling test to see what happens. Then go from there.
Progress report: I'm finally to the point where I can start doing measurements. I got bogged down gluing lots of thin foam rubber sheet material to the sides, top, and bottom. Then I starting adding red inlays and accent bars, which took even longer. It is a little rough looking here and there, but I think it looks OK. What do you think?
Photo below: The black foam also serves as the gasket to seal & flush mount the driver.
Photo below: The PVC adapter end cap is removable, so I can add branches later, if needed. The initial port tuning, if any, will be external, then enclosed inside later to be compliant with theme rules.
Below photo: I made two banana jack input brackets from scrap material on hand. The initial xover will be external, then enclosed inside later to be compliant with theme rules.
Photo below: I installed two banana jacks on the PVC adapter/enclosures. To keep them from coming loose over time, I mixed up a batch of epoxy and glued a small masonite block between the two jacks. I poured the epoxy along the sides of the block and onto the mounting nuts. This will never come loose.
Photo below: While I was at it, I also finished the bottom with another red inlay and accent bar.
I like the red on black. Very bold statement and they were my high school colors. Seems so long ago... I digress!
I always forget about pvc as enclosures on mids.
https://www.jfcomponents.com/
Makes sense here where trying to limit/control lower end without HP filter. My preference is open back (-ish) on mids to attenuate reverb back through driver.
Have you not found any stuffing combo that nullifies this effect? (Anyone?)
Wolf mentions constructing a dual chamber with different volumes/stuffing for mids in the past . . .
Another nice thing about this particular PVC enclosure is that I can convert it into a single or dual chamber reflex by simply removing the back plug and swapping in some PVC crosses or Tee fittings. I currently have an extended bass shelf model set up in software that shows that I can feed 50 watts into each PS95 and get an SPL up to about 100dB above 200Hz without exceeding X-mech ( 8mm). The cone never goes above 5mm all the way down to 19Hz. Sounds too good to be true. Personally, I think the modeling software is wrong, but I plan to test this idea to see if it really works.
No. The stuffing dissipates some of the resonance as heat. That is it. But at least you do not have the problem of room resonances (open back) or strange 200Hz to 1kHz peaks (bass reflex) vented out the port hole.
Thanks, Craig! And the colors just happen to match PE's banana jack colors as well.
It's all a compromise. Over stuff the mids and it is lifeless, no stuffing and it leads to distortion, no housing and you loose cone control. ABC chamber can give bass and cone control at the expense of volume and complexity. There is a reason all these methods exist and are used. No one has any exclusive knowledge when it comes to midrange design. This is also an area where the measurements don't tell you everything.
Same here...
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My understanding is that a cone is mass controlled above resonance? According to a brief conversation that I had with Curt Campbell.
Agreed. For the 1st experiment, I'll be stuffing the small, sealed PVC enclosures with a handful of denim Ultratouch, then swap in a handful of Acousta-stuf, then swap in a handful of poly fil. Run impedance curves and listen. Then I'll build and try out a small, extended bass shelf alignment. Run impedance curves and listen. Will also attempt to model and build a small Aperiodic Bi Chamber (ABC). The box volume sizes are not that gigantic for this small driver, but the port lengths start to get very long and need several 90 degree elbows to keep everything within the 1.25 cu.ft. spec.
I also have a design that I am considering that uses a dual chamber aperiodic for the mid or 2 mids in my case
Sorry, i may have misunderstood, no enclosure as open back . What is ABC?
One of the programs calls a double chamber reflex design an ABC. Bass Box?
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Aperiodic Bi Chamber.
I use ABC as DCR is widely used electrical term, life is confusing enough.
An aperiodic dual chamber isn't a DCR or DBR. DCR and DBR aren't aperiodic, but i understand your perspective. I use MAPD for the multichamber aperiodic design from Northcreek fame. I see ABC used interchangeably between MAPD and DCR types, which gets really confusing, even if the program models both under the same name.
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I'm going down this rabbit hole as well. I have one speaker set up and I'm currently swapping out enclosure types and running impedance curves on each setup. The PS95-8 in small sealed PVC enclosure with a handful of Ultratouch denim stuffing gives an in-box Qtc of 1.2. Sounds kind of punchy. So I'm boosting the size of the PVC enclosure by adding PVC extensions, elbows, branch pipes, etc. I'm trying to get the lowest possible Impedance peaks and Qtc measurement, while still obtaining good cone control on low bass notes. So far, the best one that I have stumbled on uses a pair of small 1/2" aperiodic, lightly stuffed vents along a short 7" x 1.5'ID PVC section that is also lightly stuffed with denim Ultratouch. It reduces the single monster free air impedance peak of roughly 70 ohms all the way down to two or three smaller 12 to 15 ohms bumps. The Qtc, according to DATS, comes in at about 0.65 (almost critically damped). Cone motion on deep bass tracks is slightly higher on the aperiodic configuration, but not too bad at all. I can still crank it up fairly high on material with lots of deep bass percussion stuff and the driver holds together. The small sealed PVC enclosure, for comparison, had less cone motion, but it had an impedance peak of nearly 50 ohms and a Qtc of 1.2.
Sorry for the rambling. All this talk about multichamber loading is starting to go to my head!
No apologies needed. This kind of info on these type of alignments seems rare to get.
So funneling the mid's back pressure wave down to a smaller enclosure through some light stuffing and then opening the exit of the funnel to a larger cavity sounds like a good possible solution?
Sounds about right to me [logically].
Yes, that would be best practice.