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Directiva r2 monitor prototype build
- Thread starter Rick Sykora
- Start date
OP
- Thread Starter
- #162
Yes, can share but we are starting with the baseline @TimVG provided.
From here on out, it is a matter of the materials we have on hand and some trial and error. It is mainly a matter of varying the poly fill. The foam lining the sides appears to be beneficial as well. It is mainly a balance between loading the woofer and ensuring enough dispersion from the slots across the target frequency range.
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OP
- Thread Starter
- #163
Here is an early look using a sim with the anechoic data gathered over the weekend. In this case, the crossover is BU5 at 1600 Hz. We are still experimenting with dampening and crossover variations, but this shows some promising potential. NOTE: we are not sure of the anechoic data below about 300 Hz. Bear this is in mind as this heat map below looks overly optimistic.
Will know more once we get to measure the fully implemented design.
Will know more once we get to measure the fully implemented design.
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So that there are no misunderstandings, here is only the relevant part down to 200Hz. It is planned that the crossover frequency to the bass module will be between 150-300Hz - depending on the maximum sound pressure level targeted for Directiva r2.
CTA-2034 and normalized hor and ver sonogram**
*** 
**In the vertical frequency response measurements, the speaker was lying on its side and the slots were partially blocked, so the vertical measurements show a transition to omnidirectional radiation below 400Hz, which would not occur if the slots were not partially blocked
*** In the CTA-2034 diagram, the lowest gray curve shows "ERDI vertical" (which is not shown in the standard). Above is ERDI and the red curve above it is SPDI.
The VCAD simulation of the crossover (here in the example active BU5@1600Hz) is based on anechoic data measured by @Justin Zazzi for the individual drivers of Rick's Directiva r2 prototype. A big thank you to Justin, because this step in the development is very time-consuming and crucial for the crossover design.
What the diagrams show is the real expected radiation behavior of the speaker when using the specified crossover.
CTA-2034 and normalized hor and ver sonogram**
*** **In the vertical frequency response measurements, the speaker was lying on its side and the slots were partially blocked, so the vertical measurements show a transition to omnidirectional radiation below 400Hz, which would not occur if the slots were not partially blocked
*** In the CTA-2034 diagram, the lowest gray curve shows "ERDI vertical" (which is not shown in the standard). Above is ERDI and the red curve above it is SPDI.
The VCAD simulation of the crossover (here in the example active BU5@1600Hz) is based on anechoic data measured by @Justin Zazzi for the individual drivers of Rick's Directiva r2 prototype. A big thank you to Justin, because this step in the development is very time-consuming and crucial for the crossover design.
What the diagrams show is the real expected radiation behavior of the speaker when using the specified crossover.
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OP
- Thread Starter
- #165
Wow, between other tasks and such, another month has slipped away. Not much new to report on r2 unfortunately. Along with holidays, Justin has changed jobs and is the process of moving. I have had a sudden spike in amplifier business and this should help cover some Directiva project costs.
Am waiting to hear from Justin and one of us will post another update soon.
Am waiting to hear from Justin and one of us will post another update soon.
OP
- Thread Starter
- #166
Justin is moving halfway across the country and the r2 prototype is with him.
Expect he will need a few weeks to settle in!
Expect he will need a few weeks to settle in!
OP
- Thread Starter
- #168
For the monitor, the driver costs are under $400 for a stereo set. Justin just got in another spin over the weekend and the results look pretty good but the current crossover is active only and will need to develop a passive one. The spin will give us the raw driver data to do that and then can tally the parts cost. The cabinet is labor intensive but not much MDF is needed. Expect we will have that cost by end of month.
For total cost, the system needs a bass driver and at a minimum that will be $150 for a pair of decent 6.5 inch woofers. With this approach could turn the monitor into a 3-way. Would likely double the cabinet size and then add another $100 for crossover parts. Double that for a set of four and a couple of minitowers knock-down cabinets. Those cabinets should be less than $100 each but am waiting on PE to get new ones. For more serious bass, figure the cost of a set of 4 Dayton RS225s and enough MDF to build a couple of 2.5 cubic foot cabinets.
Hope this helps. When the design is more complete can be more specific. My original cost target was $1600 for an active system without amps. That seems very doable. With passive crossovers in a small 3-way monitor, I estimate around half that.
For total cost, the system needs a bass driver and at a minimum that will be $150 for a pair of decent 6.5 inch woofers. With this approach could turn the monitor into a 3-way. Would likely double the cabinet size and then add another $100 for crossover parts. Double that for a set of four and a couple of minitowers knock-down cabinets. Those cabinets should be less than $100 each but am waiting on PE to get new ones. For more serious bass, figure the cost of a set of 4 Dayton RS225s and enough MDF to build a couple of 2.5 cubic foot cabinets.
Hope this helps. When the design is more complete can be more specific. My original cost target was $1600 for an active system without amps. That seems very doable. With passive crossovers in a small 3-way monitor, I estimate around half that.
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OP
- Thread Starter
- #169
Fyi, Justin has done some more spins of the r2 prototype and we are still working out some kinks in the data. After comparable struggles with r1, was hoping a more proven test setup would get us to closure more rapidly but has not turned out as I hoped. As have been revamping my test rig (has a lot of shimming to deal with using a plastic carousel), am considering building something better as it slows my other projects too. Hope to be posting a release candidate r2 VCAD project soon.
Would any of these help? https://www.mcmaster.com/products/lazy-susans/round-turntables-7/
OP
- Thread Starter
- #171
It is the right idea. These can be found on Amazon too. The primary issue is you spend more to get something better and is so smooth it needs a mechanism to lock it in place. An indexing table solves that but is even more.
When I used to make ceramic pots we used metal wheels for applying finishes, removing features, etc. The wheels were rock solid and were just turned by hand.
Something like this?
OP
- Thread Starter
- #173
Interesting, am not sure. Ever done a top heavy 4 ft tall pot perched on half the turntable? That is the speaker use case.
Hmm, half on makes in interesting.
How about a moving dolly (https://www.homedepot.com/p/Anvil-800-lbs-Capacity-18-in-Wood-Furniture-Dolly-HDWD002/315649433) with a captive pin to act as a center of rotation?
OP
- Thread Starter
- #175
Yes, have seen one like that where one wheel was removed. It is not just the one axis of rotation though and measurement angles need to be repeatable as you change height for each driver. I have a decent idea of how to implement but the fabrication would be more difficult with my current turntable. Enough here for now unless you want to start a new thread or PM me.
I've started a thread called DIY spinorama turntables. Haven't worked out how to post a link to it though (still wobbling around on my L plates lol)
somebodyelse
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OP
- Thread Starter
- #179
Finally, a clean set of measurements. Special thanks to @Justin Zazzi!
The crossover is a hybrid active/passive....
Now we can experiment a bit more and tune it. To integrate a passive crossover, the cabinet needs more depth. We already know the internal damping needs to be consistent and so are looking for better material(s) for that. We think we should be able to reduce the number of slots and see indication that we need to move them further away from the woofer. A clean spin helps us determine how well the sims correlate to the real world.
Special thanks to @Justin Zazzi!The crossover is a hybrid active/passive....
Now we can experiment a bit more and tune it. To integrate a passive crossover, the cabinet needs more depth. We already know the internal damping needs to be consistent and so are looking for better material(s) for that. We think we should be able to reduce the number of slots and see indication that we need to move them further away from the woofer. A clean spin helps us determine how well the sims correlate to the real world.
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