Minerva Monitor: "Patience my ass, I'm going to go build something!"

**cochinada** · 31 March 2016, 03:18 Thursday

I second that. Speedy recoveries to both of you. Here is some music for relaxation (or falling a sleep, whichever happens first):

Meditation Music for Chakra Balancing and Healing Music Sound Therapy

https://www.youtube.com/watch?v=V73uMzjkIkg

► Get your copy on iTunes: https://itunes.apple.com/us/album/chakra-balancing-2014-chakra/id881136760► Join my website http://meditationrelaxclub.com/ Relaxi...

**Steve Manning** · 31 March 2016, 09:03 Thursday

Originally posted by sdl2112

Steve...your nice work continues. I haven't done much on my project lately but I will post a small update shortly.

It's funny...not really "ha ha" funny but the day after I wish Jon good luck with his procedure...I ended up in the ER Monday. I had an atrial fibrillation event with high heart rate. I had a similar episode earlier in the year. Everything is going good and we have a plan to get things sorted out. It's just a dose of reality the older we get.8O

Scott that sucks ...... your right about the getting older part ..... I'm sure they'll get you straightened out, let us know how it goes.

**JonMarsh** · 31 March 2016, 10:18 Thursday

Originally posted by sdl2112

Steve...your nice work continues. I haven't done much on my project lately but I will post a small update shortly.

It's funny...not really "ha ha" funny but the day after I wish Jon good luck with his procedure...I ended up in the ER Monday. I had an atrial fibrillation event with high heart rate. I had a similar episode earlier in the year. Everything is going good and we have a plan to get things sorted out. It's just a dose of reality the older we get.8O

So sorry to hear about his Scott- my original hiring manager for my current job, (30+years) had this crop up in the mid 2000's; he's doing fine for some time since then, but a big part of it was managing stress and diet better- cutting out caffeine, more excercise (which for him is ballroom dancing- he's very good at it, met his new wife that way 5 years ago) and a glass of wine at the right time in th evening, if you can believe. I hope your specialist helps you get things sorted out quickly.

At times it's not fun getting older, but on the other hand, I think it beats the alternative. :W

A couple of years ago I did some Google searches for guys I used to play with in bands while working my way through college in the early 70's- most of them aren't around anymore. Heart attacks, typically. But then, a lot of guys who are musicians at some point in their lives don't always make the best lifestyle choices, either, unfortunately.

**JonMarsh** · 31 March 2016, 10:21 Thursday

Originally posted by cochinada

I second that. Speedy recoveries to both of you. Here is some music for relaxation (or falling a sleep, whichever happens first):

https://www.youtube.com/watch?v=V73uMzjkIkg

Thanks for the link!

Didn't have much trouble falling asleep last night, though it was sort of weird, I got down to a sort of trance level like what happens when I do self hypnosis, and was there for quite a while before really falling asleep. And then I had to get up again soon- after a procedure like this, you're lucky to get two hours between bathroom breaks for a few days, night or day!

**JonMarsh** · 31 March 2016, 10:22 Thursday

Originally posted by ergo

Lets hope all these nice speaker projects bring some relaxations and tranquillity through music after the completion. Seems too much work and not enough play is a general problem.

Best of luck for both of you with recoveries.

Thanks Ergo- you too, Bill and ALaric - things went as smoothly as could be expected, follow up is on the 8th, to remove another stent. I'm looking forward to this being in the rear view mirror, to mix my metaphors a little bit!

**sdl2112** · 31 March 2016, 12:10 Thursday

Thanks for the kind words everyone :T.

Jon...I'm glad to hear your procedure went well.

I feel confident I will get this resolved. The tentative plan is for a cardiac cryoablation procedure where they freeze the pathways that interfere with the normal distribution of the heart’s electrical impulses. I will likely have this done end of April. This along with more regular exercise, reduced stress and diet as you say Jon will help.

**ergo** · 31 March 2016, 14:03 Thursday

Slow but sure progress.

One box assembled. I have 10mm felt on side, back and bottom panel in mid enclosure + 100g of TWARON Angel hair filling. On woofer box I have only the 10mm felt on two side panels. Left the lamb wool meant for additional stuffing out for now to better see the box alignment. Fsb is 29Hz now, but these are fully virgin drivers that have not seen any work yet, so may be it will lower just by working them in.

**JonMarsh** · 31 March 2016, 14:28 Thursday

Well, you're pulling well ahead of us in the build completion sweepstakes! Hopefully by the weekend I may be up to working on the 2nd gen acoustical prototypes, but I have a feeling GF will be keeping a close eye on me from doing anything very strenuous, or even mildly strenuous!

Looks very nice! :t

**ergo** · 31 March 2016, 17:24 Thursday

The VituixCAD and the ARTA automator from Kimmo really triggered a big want to attempt me to make true 180deg horizontal and 360 vertical polars this time.
Now the problem is that the turntable I have would suffice for horizontal polars. But vertical would need something else. My boxes being much taller also make it hard to rotate them to lay on the side and at same time turn them.... so I had an idea for a contraption that moves the mic instead. The current plan allows 10deg steps from 0...180 and if the inner piece of the arm is turned upside down it can go the other way to 180 too. Will think about it tomorrow some more and if I still like the idea I'll try to cut this out from the bamboo scraps I have left.

[ATTACH]25519[/ATTACH]IG]25518[/ATTACH]

Attached Files

**JonMarsh** · 31 March 2016, 17:49 Thursday

Agressive and interesting. I'm planning on doing a detailed horizontal polar, but haven't convinced myself that the vertical is as necessary, considering the driver characteristics.

**ergo** · 31 March 2016, 17:58 Thursday

Sure. I predict the same for this project... but sorta using the momentum to make this happen as next projects might need the vertical polar data and then this is addon to measurement stuff will come handy.

**Steve Manning** · 31 March 2016, 19:08 Thursday

Originally posted by JonMarsh

Well, you're pulling well ahead of us in the build completion sweepstakes! Hopefully by the weekend I may be up to working on the 2nd gen acoustical prototypes, but I have a feeling GF will be keeping a close eye on me from doing anything very strenuous, or even mildly strenuous!

Looks very nice! :t

Problem is though, he's two more cabinets to do and then four stands to make it a fair match

**JonMarsh** · 31 March 2016, 21:26 Thursday

well, if you count my LBL acoustic prototypes in progress here in CA, then he has 4 more cabinets to do!!! :B

Of course, some might say it's quality, not quantity, and if he has his working first.... :W

OTOH, I do have one built crossover, that may be pretty close to final configuration, and parts for another...

**cochinada** · 01 April 2016, 03:41 Friday

Originally posted by ergo

The VituixCAD and the ARTA automator from Kimmo really triggered a big want to attempt me to make true 180deg horizontal and 360 vertical polars this time.
Now the problem is that the turntable I have would suffice for horizontal polars. But vertical would need something else. My boxes being much taller also make it hard to rotate them to lay on the side and at same time turn them.... so I had an idea for a contraption that moves the mic instead. The current plan allows 10deg steps from 0...180 and if the inner piece of the arm is turned upside down it can go the other way to 180 too. Will think about it tomorrow some more and if I still like the idea I'll try to cut this out from the bamboo scraps I have left.

[ATTACH]25519[/ATTACH]IG]25518[/ATTACH]

Ok, for the horizontal plan it is clear how you're going to do it; you just need to place the baffle axis exactly at the centre of rotation, so X marks the spot but for the vertical rotation I'm not understanding how do you plan to rotate the mic around each driver centre with that strange contraption keeping the distance constant at the same time. :scratchhead:

EDIT: or is that contraption meant only for rotating the mic on the horizontal plan instead of using your turn table?

**ergo** · 01 April 2016, 14:30 Friday

My chain of thought is...
* horizontal plot can be done relatively easily with the type of plate I have. The front panel is adjusted in line with the axis going through the center bolt.
* vertical would be harder - doing it really in vertical plane would need a different kind of solution - probably also moving the mic not the speaker
* I'm planning to tilt the speaker on it's side and do another horizontal sweep of angles, but as the coax is in about 1/4 the lenght of the box it would never be in balance on the stand. Adding a second stand will make it very hard to rotate the box.
* so the solution with above is to always rotate mic around the speaker in horizontal plane - this way I can build additional supports to keep the long box tilted on its side in balance.
* I will do 0 to 180 in horizontal as it'll be symmetric to other side
* I'll do 0..180 towards top vertically and then some angles in other direction and see if it shows any significant difference to justify really doing the 0..180 towards bottom also.

I've never done any speaker that thurally - so just interested to try the process and see the data. VituixCAD tools make it tolerable workload to later process all that data too... that used to be a problem with my prior tools (just ARTA or CLIO with LspCAD)

**Steve Manning** · 01 April 2016, 19:58 Friday

Small update ...... finished with the coax cutouts and started with the woofers. Starting to look a bit like a speaker.

**sdl2112** · 01 April 2016, 22:43 Friday

Steve...I bet you are glad that step is out of the way. Good job. :clap:

**Steve Manning** · 02 April 2016, 10:38 Saturday

Originally posted by sdl2112

Steve...I bet you are glad that step is out of the way. Good job. :clap:

Almost .... that's the first one ...three more woofer cutouts and then I'm done, and yes I will be glad to see that behind me. Yesterday I timed it and it took 25 minutes just to router out the slug of wood. All told just the routing process for the one hole was ~75 minutes. That's a lot of puckering.

**JonMarsh** · 02 April 2016, 12:13 Saturday

Indeed it is! Slow work takes time....

**ergo** · 02 April 2016, 15:34 Saturday

I did finish the 'Mic rotator helper tool' today and did some practice rounds before attacking the Minervas tomorrow.

The result sample is from my ModulaMT mkII EE version (I used the Nextel series woofer). These are just a plot of the gated responses (4.5ms gate) - so not valid below 500Hz or so but still ineteresting from there upwards.

**TEK** · 02 April 2016, 19:45 Saturday

Great progress!

**cochinada** · 03 April 2016, 05:15 Sunday

Nice contraption and beautifully made. :clap:

From what I've learned with Kimmo, there are some issues with directivity though, specially above 5KHz where there is a clear deviation from a straight line, if I'm not mistaken. I had also problems in my project and for the same reason could not optimize the on axis response as much as I would have liked. I'm very curious to see the directivity on this Minerva with the coaxial driver...

**ergo** · 03 April 2016, 12:31 Sunday

After a full day of effort I did get it all done. Twice actually as at first round the SPL was not right and then the engineer in me would not let it go and I redid all again. the repetition is a good teaching method so I'm sure I'll remember the tricks that much better next time.

I used a lab microphone thats good to 40k, so I also wanted to get the SPL right as I do have the calibrator.... Now getting ARTA to get right levels was a bit of hassle. If one does the microphone calibration, then for example the SPLmeter sub module starts to show correct level right away. The 2 channel IR measurements is different though. In end I had to calibrate both left and right input and then also the microphone SPL -> mV before I got all working.
Did the whole 0..180 deg horizontal polars -80... +170 vertical polars - will try in one of the next days to take some 4..5 angles from each and calculate average for example. Then I get to see if the verticals are needed at all.

Anyhow. Below are the setup pics + the initial gated measurements entered to VituixCAD. I'll need to follow the process of merging those with the near field measurements and baffle simulation to get it correct in lows also.
Still, not bad and reasonably close to Jon's, but not 100% match. But thats to be expected I guess.

I'll organize the data in clear folders and put it up in Onedrive too in case anyone's interested.

**ergo** · 03 April 2016, 12:32 Sunday

Mid offaxis

Woofer offaxis

**ergo** · 03 April 2016, 12:37 Sunday

I might have some luck also with the bass in room. This is a measurement of the unfiltered woofer in my listening room left and right speaker position. Seems the room modes are nicely different in both positions, so hopefully the sum is ok... but I'll need to finish the second box and crossovers before I get to know that.

**ergo** · 03 April 2016, 12:42 Sunday

By the way Jon, when taking measurents if and what value of protection capacitor you use for tweeter? I used 200uF in these. Did not dare to run these tweeters without any cap.

**ergo** · 03 April 2016, 13:25 Sunday

This one is now Jon's V1.1 cross with my polar data (horizontal+vertical). Woofer and mid have now been merged with near field measurements and baffle step simulation shape added also.

I've also uploaded all of the project files here. So in case someone wants some real data to play around with VituixCAD then it's all there.

Onedrive link

**cochinada** · 03 April 2016, 14:01 Sunday

And if someone's interested I've modeled the SEAS C18EN001/M driver in Sketchup. I just had some pictures to start with and a few measures, so this is not a very precise drawing. Anyway I guess it might be fun just to incorporate it on the box drawing. BTW I estimate the volume inside the box to be about 3.2l.

Image not available

And you can download the *.skp here:

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**Steve Manning** · 03 April 2016, 15:13 Sunday

Originally posted by cochinada

And if someone's interested I've modeled the SEAS C18EN001/M driver in Sketchup. I just had some pictures to start with and a few measures, so this is not a very precise drawing. Anyway I guess it might be fun just to incorporate it on the box drawing. BTW I estimate the volume inside the box to be about 3.2l.

Image not available

And you can download the *.skp here:

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Thanks on the drawing .... looks a lot better than the one I cobbled together.

**ergo** · 03 April 2016, 16:16 Sunday

Very nice model indeed

**cochinada** · 03 April 2016, 16:30 Sunday

I forgot to tell: you need to scale it down to 0.1 for the real size. As most will know, in Sketchup is better to work with large scale, otherwise we'll have problems when things get too little.
I'll be working on the other two drivers. They look a lot more simpler than this SEAS.

**JonMarsh** · 03 April 2016, 16:37 Sunday

Comments-

Nice setup and measurement work-

Keep in mind, my "first gen proof of concept" was using the PE box and sub woofer cube, so baffle widths aren't right, and I wouldn't expect that data to match yours in a number of areas.

It's cool to have someone else doing this measurement work also- I'm wondering if I should measure both in Fuzzmeasure as I usually do, and also with the AP setup- but as the mic and preamp and physical setup will be the same, I wouldn't expect any significant differences.

And that's why I have what I call 2nd generation acoustical prototype cabinets in build process, to get something that is dimensionally about the same as the end product:

This was the VituixCAD crossover as modeled from my first measurement data. If there are any errors in level or what not, then of course that will propagate through. I had to re-arrange the network compared with my LspCAD formulation- and I note that the midrange input resistor is quite a bit higher in the LspCAD version (12 ohm) versus 9.1 in the VituixCAD topology. I won't trust any of this until I've gone through new measurements, but as I think you are noting, running through the process more than once is competency building. That's why I do it with the crossover modeling and review, thinking about what may be interacting and double checking impedance optimization.

Looks like a very nice driver model for the C18 in Sketchup- have to see if we can export that to some other formats.

**ergo** · 04 April 2016, 00:40 Monday

My version has the coax/woofer driver spacing of 260mm (10.2inches). This should be quite close to what your proof of concept box and the boxes Steve is making also I hope.

**meb46** · 04 April 2016, 01:31 Monday

Steve - That's some might fancy Bamboo Mic Tooling - Love it!

**Steve Manning** · 04 April 2016, 09:19 Monday

Now we can sort of celebrate Scott ...... last of the driver cutouts are done.

Started into what others of you perhaps wisely avoided ...... threaded inserts for the drivers. First cabinet is done so I did a fit of the drivers.

**Steve Manning** · 04 April 2016, 09:21 Monday

New custom router bit did a great job of leaving plenty of breathing room around the back of the drivers ......

**JonMarsh** · 04 April 2016, 09:25 Monday

Inserts... In LBL. This guy is a hardcore craftsman!

Yeah, the Whiteside bit has done a great job all in all!

I'm really enjoying seeing those drivers mounted in a cabinet! :T

**ergo** · 04 April 2016, 10:05 Monday

Very nice work.

I tought about threaded inserts too, but seeing how strong and hard the bamboo is I tought that it will probably hold a regular screw also much harder than BB or MDF.

The Seas coax is so pretty from backside too that it's almost a pitty to hide it in a box... but then again the sound is what will really matter in the end and the looks comes after. And with this project the looks side is cool too still.

**Steve Manning** · 04 April 2016, 11:35 Monday

Originally posted by ergo

Very nice work.

I tought about threaded inserts too, but seeing how strong and hard the bamboo is I tought that it will probably hold a regular screw also much harder than BB or MDF.

The Seas coax is so pretty from backside too that it's almost a pitty to hide it in a box... but then again the sound is what will really matter in the end and the looks comes after. And with this project the looks side is cool too still.

Thanks Ergo ...... one could always do acrylic sides if you wanted to see the drivers from the back. At an 1 1/2" thick I don't think it would flex much.

**cochinada** · 04 April 2016, 15:32 Monday

Ladies (where are they?) and Gentlemen, please welcome the Wavecor SW223BD02...

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and the skp model...

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**ergo** · 04 April 2016, 15:56 Monday

Looks cool, but model wise I think you linked to same 'C18EN001_M.skp' - at least that what opens for me.

**cochinada** · 04 April 2016, 16:25 Monday

Sorry about that. It's corrected now.

**sdl2112** · 04 April 2016, 21:29 Monday

OK Steve now I can say good job. Inserts too :T...they give you more hardware options.

As far as the rear breathing...that's one thing I really like about the C18en with the small neo motor...along with your nice rounding job of course.

**Steve Manning** · 04 April 2016, 21:49 Monday

Originally posted by sdl2112

OK Steve now I can say good job. Inserts too :T...they give you more hardware options.

As far as the rear breathing...that's one thing I really like about the C18en with the small neo motor...along with your nice rounding job of course.

I guess now I can say thanks ..... again.

Got the inserts finished on the cabinets this afternoon, 80 in all for the cabinets. I did some tests a while back and discovered you need to go over the recommended pilot hole size or the threads shear off on the brass. Once I got that figured out they went in nicely.

I got lucky finding that bit with the ability to get a longer spindle from Whiteside. It mowed right through the lbl no problem and had plenty of reach for the 2 1/2" thick material.

**cochinada** · 06 April 2016, 06:12 Wednesday

And voilà the last of the three...

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and the model...

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