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

[JonMarsh]

Let's see if this is more readable- it's slightly shrunken from the PNG in pixels, and quite a bit in file size

[ergo]

I have the project in VituixCAD and LspCAD both. Correlation between them seems very good. I used LspCAD for this because the way VituixCAD handles the component designations and list is a bit cumbersome with this many items (one can show schematic with values or component designations, but not both)

[JonMarsh]

I have the project in VituixCAD and LspCAD both. Correlation between them seems very good. I used LspCAD for this because the way VituixCAD handles the component designations and list is a bit cumbersome with this many items (one can show schematic with values or component designations, but not both)

That is DEFINITELY true- we should put together a little list of suggested improvements- it may be that it's not feasible to do because of how he handles the schematic entry. There are some other points, too, at some time I've got to send him an email or two.

And I think I just found where to export measured data into an Excel file- need to review a few more points, but I'm getting comfortable.

One cool thing is that be default the software detects the location of the first reflection and windows on that automatically- and the software does NOT do any smoothing- so you can push it beyond that point, but then you get all the stuff from the reflections. The nice thing is you don't even have to figure it out and it shows you where the LF data is invalid/untrustworthy due to sample length by overlaying a gray region. I think I could get used to this, but I also think I want to master Fuzzmeasure 4; right now I've been using three still, because there really isn't much documentation on 4, and it works quite differently.

One of my biggest productivity sinks is needing to learn new software...

[ergo]

Will be interesting what that auto gating will do for tw / mid / woofer. The impulse of each will have a peak in different places and shape wise different, so the start point might get interpreted differently too.

I have an NTi Flexus FX100 at work (a cheaper competitor for AP). Tried that the other day out of interest. One can also use gated measurements there and that side works, but phase plot will be a on a different plot and one can't export the frd and phase into same txt file. So another post process will be needed etc.

All in all it seems that the 'perfect' speaker measurement system is still to be found/made

PS. I have started that list for VituixCAD already, we can sync those ideas at one point indeed.

[sdl2112]

Quick Update ....... finished fabricating the trim pieces for the stands this afternoon, after the lawn got mowed. Clean up, scratch removal and polishing remain on all of the trim, as well as applying a clear coat.

[ATTACH=CONFIG]25627[/ATTACH]

That's going to look nice Steve. What are you going to clear coat the Al with?

[JonMarsh]

All in all it seems that the 'perfect' speaker measurement system is still to be found/made

PS. I have started that list for VituixCAD already, we can sync those ideas at one point indeed.

That's certainly true...


Working with the AP, I have to setup the specific measurement data results that I want for a measurement (RMS value, phase, Distortion level, distortion ratio, etc) do the measurement, clip or export the graph images if I want to save them, and then for each measurement export an XL file which will have all the measurement data for each graph on a separate sheet. And something like RMS level and phase can't be conveniently combined, and require post processing in XL to make a combined graph or to create an FRD file.


Thing I do like about the APx500 Acoustics measurement:

• Very simple equipment setup- just plug the BNC output of the ACO Pacific 9200 interface into an unbalanced BNC channel input on the AP
• Sensitivity and dynamic range on the input of the AP covers even low level mic signal
• Put the calibrator on the microphone, turn-on, and go to Inputs>Reference Levels and set what's coming in as the reference for dBSPL1 (std 94dB) and you're all set to go
• Inputs and outputs can have limits preset on them so you don't fry downstream gear
• AP Equiripple windowing seems to be a very good measurement window...
• Easy to set individual graphs as free floating windows and on a large screen monitor workflow give good overview- 2560x1440 or 2560X1600 recommended
• Automatic windowing and separate impulse window for manual adjustements and override

Things I don't like are the lack of a straight forward minimum phase function such as Fuzzmeasure has; best solution is to use Excess phase display and window the response area of likely minimum phase (such as selecting 400Hz to 3 kHz for the midrange of the C18EN001). Also, it would be really desirable to have a project function which saves all the data in your measurements and allows you to go back through them; bench mode testing doesn't seem to support that, though I believe Sequence mode does.

I still have a lot of documentation to read and re-read, so I may find the answer is a lot simpler than I expect... or not. :B


I could see the possibility/likelihood of splitting up tasks for measurement, depending on the task at hand; for fast driver investigations and measuring and tweaking a system in room, seems like the AP may be a great tool. For generating driver measurements for design, I'm likely to keep using Fuzzmeasure, though I think I need to bit the bullet and see if I can get up to speed on version 4, now that there have been a few updates to it. There are some basically different things about it's work flow, though- OTOH, it is a lot more flexible and powerful for some new activities. And it does support calibrators in the new version. I do need a different mic preamp/computer interface, and have ordered something new to try out- a Tascam unit with more mic gain- should be here before the end of next week.

[Steve Manning]

That's going to look nice Steve. What are you going to clear coat the Al with?

Thanks Scott ..... I was thinking of just picking something up at Lowes in a spray can. It's mostly going to be on there to prevent oxidation.

[Steve Manning]

With all this talk of crossovers ..... here's something for you to mount all of your bits and pieces on Jon. I knocked some boards out this afternoon for all of the components to mount to. The boards will mount upside down in the compartment, with, you guessed it, threaded inserts. McMaster got an order for some more 8/32" inserts and 316 SS screws this morning.

[JonMarsh]

Looks very good, Steve... I'll be sure NOT to build anything on one of THOSE boards until it's completely debugged!

Been working a bit on that today...

Mostly getting some driver testing and data export experience with AP, but also tried the old V1 crossover, which though a little bright doesn't sound bad at all with the new cabinet setup, and the 851D as the source.





I was so focused on data extraction I didn't get hardly any driver measurement clips, but I did do a few with checking the 1.0 crossover (old topology on LspCAD 6)


On axis





30 degrees Off axis




45 degrees Off axis

[5th element]

One of the things I like about this design is the width of the cabinet. Usually people like to go for as skinny as possible, but going wider has its advantages too. Most notably because it shifts the baffle step transition down in frequency and the diffraction peak/dip usually encountered before it, down with it too.

Given the targeted xover frequencies here and the width I'm guessing that the baffle step transition occurs completely outside the range of the midrange driver, meaning nothing is required, in terms of compensation, to flatten it out. That and the diffraction bump should be off the radar too. Whether or not this actually results in a better sounding design it certainly makes things easier to design.

[ergo]

I would say we have a very good matching now with our measurements.

These graphs are my measured data + simulation with Jon's V1.1 crossover values and gray REF line is the AP measurement Jon just did

At 0deg


And at 30deg

[JonMarsh]

One of the things I like about this design is the width of the cabinet. Usually people like to go for as skinny as possible, but going wider has its advantages too. Most notably because it shifts the baffle step transition down in frequency and the diffraction peak/dip usually encountered before it, down with it too.

Given the targeted xover frequencies here and the width I'm guessing that the baffle step transition occurs completely outside the range of the midrange driver, meaning nothing is required, in terms of compensation, to flatten it out. That and the diffraction bump should be off the radar too. Whether or not this actually results in a better sounding design it certainly makes things easier to design.

It's close to being the case-- BSC is occurring at 400-500Hz, I'll take my data exports and make some graphs in Excel or Numbers to show what the measured driver response looks like.

[JonMarsh]

I would say we have a very good matching now with our measurements.

These graphs are my measured data + simulation with Jon's V1.1 crossover values and gray REF line is the AP measurement Jon just did

At 0deg
[ATTACH=CONFIG]25649[/ATTACH]

And at 30deg
[ATTACH=CONFIG]25650[/ATTACH]

After reviewing this and the measurements done yesterday, I have a few conclusions/suggestions how to proceed-

I think I had an issue with SOME of my initial data used for design becuase I was taking long gate measurements and smoothing the data, which is NOT (as I realize) the same thing as short gated measurements in the appropriate frequency range.

I think an efficient way to proceed considering the agreement above is to take your measured data (to save time for now of processing what I did yesterday) and do design checks with the 1.1+ network and any considered tweaks (such as the down slope voicing) and focus on 0, 15, and 30 degree data, as combined the 15 and 30 particularly will dominate the power response and the typical listening angle.

Sound OK to you? I'm hoping we can further improve the flatness in the 1500Hz to 5kHz area where the ear is quite sensitive, and come up with a voicing that works well with agreed psycho-acoustic principles and our gear. If you favor the full 6dB/decade slope, let me know, should be able to accommodate both. Also, I'll start reviewing your Excel in detail, hopefully I can download to disk, figure out any updates if desired, and then go back online and update yours.

I've got a very busy week with three days of advanced simulation training Wednesday through Friday, conference calls re FAE training today, and will be in the office all day tomorrow on logistic issues, so progress on my end will likely be slow until next weekend.

[Steve Manning]

It's close to being the case-- BSC is occurring at 400-500Hz, I'll take my data exports and make some graphs in Excel or Numbers to show what the measured driver response looks like.

Jon are your cabinets the same size as the one's I'm building?

[ergo]

I think an efficient way to proceed considering the agreement above is to take your measured data (to save time for now of processing what I did yesterday) and do design checks with the 1.1+ network and any considered tweaks (such as the down slope voicing) and focus on 0, 15, and 30 degree data, as combined the 15 and 30 particularly will dominate the power response and the typical listening angle.

Sound OK to you? I'm hoping we can further improve the flatness in the 1500Hz to 5kHz area where the ear is quite sensitive, and come up with a voicing that works well with agreed psycho-acoustic principles and our gear. If you favor the full 6dB/decade slope, let me know, should be able to accommodate both. Also, I'll start reviewing your Excel in detail, hopefully I can download to disk, figure out any updates if desired, and then go back online and update yours.

I've got a very busy week with three days of advanced simulation training Wednesday through Friday, conference calls re FAE training today, and will be in the office all day tomorrow on logistic issues, so progress on my end will likely be slow until next weekend.

Sound good - yes. I did similar with above, meaning I looked at 0..40deg plots as power response and used that as a main check.

The Fuzzmeasure data I did includes also the raw Fuzzmeasure files, so you could also try to gate them different if that helps.

For woofer I took the short gate measurement and then merged it with VituixCAD with the nearfield data + VituixCAD baffle simulation. The final resulting plot I compared to the long gated plot measured at 30cm on side of the box.

Take your time with this. I have always an option to pull the trigger on the part list I have and assemble the xover. I plan to leave them outside the box for the first ... time. So it'll be possible to tweak and experiment further. It's a sort of a dilemma that bass/mid crossover is the most expensive, but also at same time the hardest to measure in 'domestic house' conditions.

Thanks for looking into these things.

[JonMarsh]

Jon are your cabinets the same size as the one's I'm building?

Very close- might be off an inch in height, half inch in width.

[Steve Manning]

Did a test fit up of the trim for the stands ...... since I recessed the trim by a 1/16" to account for surfaces irregularities and less than perfect bending of the aluminum, I beveled the edges of the grooves to give things a smoother transition from wood to metal. Of course this had to be done by hand rather than router, just due to the lack of good access with a router.

[JonMarsh]

Looks very good, Steve! it's why you're the "Go - to" guy around here!

[JonMarsh]

Sound good - yes. I did similar with above, meaning I looked at 0..40deg plots as power response and used that as a main check.

The Fuzzmeasure data I did includes also the raw Fuzzmeasure files, so you could also try to gate them different if that helps.

For woofer I took the short gate measurement and then merged it with VituixCAD with the nearfield data + VituixCAD baffle simulation. The final resulting plot I compared to the long gated plot measured at 30cm on side of the box.

Take your time with this. I have always an option to pull the trigger on the part list I have and assemble the xover. I plan to leave them outside the box for the first ... time. So it'll be possible to tweak and experiment further. It's a sort of a dilemma that bass/mid crossover is the most expensive, but also at same time the hardest to measure in 'domestic house' conditions.

Thanks for looking into these things.

[ATTACH=CONFIG]25651[/ATTACH]

Snagged your Fuzzmeasure data... Thanks!

[JonMarsh]

Version 1.4 EM+J

Using measured data supplied by Ergo, I've gone back through the version of the crossover which he sent as 1.1ALT- which is based on my original 1.1, and looks pretty good with the new data, good measurement agreement as he notes. I've reviewed component by component and have a proposal which may be similar to 1.3 in some regards, but maybe we should just call it 1.4 EM+J, to reflect Ergo measured and Jon pondered... :W I'd like to go through with the AP measured stuff, too, but this week is going to be heck, and there's some things I'd need to refine with it, as regards process flow, and then, too, there's always FM4 and the new preamp.

But based on what I've heard and measured at home this weekend with the old 1.0 crossover, I think this will work pretty well and be close or identical to what I want to build- so I'll layout the thinking behind the updates.





On the woofer crossover, the C1 for the Zobel network, changing from 91 to 150 flattens the SPL response and linearizes phase in the region between 80 and 200Hz.

On the woofer crossover, modifying the first inductor from 2.2mH to 2.3 also has a positive impact in the same area, with regard to adhering to the voicing curve.

On the midrange crossover, adjusting the HF elliptic tuning capacitor from 1.2 to 1.0 uF moves the suppression up a bit higher in frequency and does a better job of suppressing the HF spikes of the midrange cone, without messing anything else up (as far as I can tell)

On the midrange crossover, in the first shunt network, R2031 in series with the 15uFG cap, dropping to 2.0 or 2.2 ohm improves flatness, phase matching and reverse null behavior.

On the tweeter crossover, I've gone over to the 1.3 configuration removing the lone shunt inductor,
Adjusted the elliptic network values for the high pass - to 47uF and 0.47mH (not the same as the 1.3 version) to better shape the high pass function and phase
Changed the series input resistor from 9.1 to 10 ohms, for the sake of the power curve voicing taper.


Overall focus was on obtaining a 4-5 dB voicing slope and improved flatness and phase behavior in transition regions between drivers, optimizing the power curve, as I think we just have to live with the direct on axis quirks of the tweeter- at 10 degrees and beyond things are pretty manageable and I think more important overall.

[ergo]

This looks very good. This coax has quite ok on axis response, most of the other Seas ones are much worse. I'll expect to use less toe in with these speakers and that should result in good direct and reflected sound.
I'll update my part list later today and perhaps put in an order.

I was wondering if the Janzen Cross Coil versus C-coil (toroid core) would be of an upgrade in woofer xover? C-Coils are very low resistance, but in this case we have heavy currents too due to close to the 2ohm load - so perhaps a no core would be better to shoot for?

[kimmosto]

Just for information, at the moment VituixCAD needs 0-180 deg. measurement data to give correct level and shape to power response and directivity index. For example if measurement data contains only 0-90 deg. with step of 10, a single off-axis response to 90 degrees will get weighting factor of 85...180 degrees sector. That will cause some error for sure. Simplest way is just measure 0-180 with step of 10 using (manual) turning table. If 19 measurements per driver is too much, you can save few seconds by leaving every other out e.g. above 70 deg: 0, 10, 20, 30, 40, 50, 60, 70, 90, 110, 130, 150, 170. This will work fine.
I will add half space option for IB speakers within a week. That will suit better for truncated off-axis response set because program won't expect and use angles >90 deg.

[ergo]

Thanks Kimmo.

This is the new V1.4 xover with my old full horizontal (0..180) polar data. Still looks good

[JonMarsh]

Thanks for the update, Kimmo. Glad to have your feedback and hear about the upcoming option... Some of us newcomers still have a lot to learn about the ins and outs of VituixCAD software, but I'm definitely enjoying using it, and appreciate you monitoring our efforts and commenting on key points like this.

Ergo, I agree this still looks pretty good, should be usable, no doubt.

On the other point, re woofer, I do wish that we had a bit "nicer" load to drive, on general principles, but as I started this project to make a demanding speaker which would be likely to differentiate different levels of success with Class D amplifier developments both at work and personally, this striking variety of loading with impedance curve is potentially a benefit. Now, in principle, putting two woofers in series and using a large cabinet and doubling the PR count and re-designing the LF crossover would allow making a much more amplifier friendly version, albeit considerably larger and somewhat more expensive.

Now, on the subject of crossover coils, I have used the Jantzen C coils in the past, they have a pretty high power capability, but have observed one odd characteristic which makes me a bit nervous - using several kinds of LCR tester, which all test at low current, there must be a linearity or hysteresis issue with the core material, because they measure considerably higher in the initial inductance than the stated value. OTOH, this doesn't happen with the 500W Erse laminated steel core inductors. I wish I had an inductance tester for which I could ramp up the test current to say, 5 or 10 amperes, but I don't have anything like that. They exist, but are rare and tend to be expensive.

DIY testing would involve apparatus as described here:

http://elm-chan.org/works/lchk/report.html

The problem with air core inductors is they have much higher DC resistance unless you use stupendously heavy gauge wire, and they are expensive. However, we are close to the range needed for DCR... AWG14 for 2.4mH will be about 0.34 ohms, about 0.3 ohms for 1.8 mH. This higher than I would prefer to see, considering the driver RDC is about 3.2 ohms. 20% of power would be lost in coils.

Erse 500W 2.5 mH inductor is 0.16 Ohms; 1.8mH is 0.136 Ohms; much more desirable figures. These are available from PE in the USA, others carry them.

AWG 12 inductors used to be available from NorthCreek, but I think he's retired now based on the web site landing page- all products and services discontinued in 2016.

In foil inductors, a Goertz AWG12 1.8 mH is a DCR of 0.191 ohms; a 2.7 mH (needs to be unwound) is 0.275 ohms. Still a bit too high. I allocated DCR values typical for various solid core inductors. I expect to use the Erse. If you have problems getting those, let's talk about what it costs to ship to Estonia prepaid from the US. I can do UPS Worldwide service... get you some inductors!

[ergo]

Thanks Jon for the kind offer. If I would be patient enough to wait until end of May then I'm flying to Seattle area myself too and could hand carry this stuff.... but I'm probably gonna choose the faster way below.

Seems that I could get these direct from PE too and with a shipping cost that is still tolerable. Also it seems to indicate that the sum covers the import tax - if so then that would be great. Otherwise Estonias import tax+VAT is taken on full sum, parts + shipping. I've always found it very unfair. To pay VAT on goods I get is ok, but for transportation service too makes it very cost prohibitive to order especially the heavy stuff like speaker units.

I'll work through the rest of the partlist tonight and see if anything else pops up that would be available in PE and not over here.

[cochinada]

What about the C-Coil - Toroidal Core from Jantzen? The specs says:

2,5mH +/-5% 0,07Ω +/-10% 1500W / 8Ω wire 1,6mm=14AWG dia.83 h.28mm
1,8mH +/-5% 0,06Ω +/-10% 1500W / 8Ω wire 1,6mm=14AWG dia.84 h.26mm

Moreover, as they write "The C-Coil is designed for the bass section of crossovers and for passive Sub-Woofers, available in different core and wire sizes.", which is exactly what you need.

http://www.jantzen-audio.com/wp-content/uploads/2013/07/C-Coils-List-02-04-2016.pdf

Your neighbour sells it at a much more affordable price than importing from USA:

https://www.audiohobby.eu/en/jantzen-c-coil-toroidal-core/6865-jantzen-c-coil-25mh-14awg-007-ohm-r30-16-000-6100.html

https://www.audiohobby.eu/en/jantzen-c-coil-toroidal-core/6855-jantzen-c-coil-18mh-14awg-006-ohm-r30-16-000-6050.html

[ergo]

Jon wrote above

Now, on the subject of crossover coils, I have used the Jantzen C coils in the past, they have a pretty high power capability, but have observed one odd characteristic which makes me a bit nervous - using several kinds of LCR tester, which all test at low current, there must be a linearity or hysteresis issue with the core material, because they measure considerably higher in the initial inductance than the stated value. OTOH, this doesn't happen with the 500W Erse laminated steel core inductors.

One option of course is that I'll go with the C-coils at first and then when going to US also pick up the ERSE ones as without shipping it becomes much better deal... and then do the 'listen and decide' exercise which would anyway be most interesting and tell if I can differentiate them in listening..... writing this I start to like that approach the best actually.

[ergo]

Parts ordered from audiohobby. Getting them by end of month, so then the V1.4 xovers will be built and evaluated.

[JonMarsh]

Cool. Will be interested to hear your feedback. I've got to put a crossover order together, too- been focusing on electronics though, this week. Probably this weekend...

Actually been too busy at work to get much of anything done, other than ordering a few parts (chassis, special OpAmp modules, etc).

[TheWaveCarver]

Wouldn't the ERSE Super Q introduce audible distortion given that they're not air core inductors?

[JonMarsh]

Have you ever measured one? And in comparison to what other inductors? At what power level? Any test data you have would be appreciated, as my own tests show that that they have pretty dang good performance in the range up to 3kHz; I do usually only use them in LP networks below 1 kHz.

It's also important to be specific about cored inductor, becuase performance varies considerably based on core material; ferrite bobbin cores are pretty OK at low levels, but when you get to where they start to saturate, they do so very suddenly and hard- liked amplifier clipping, in some cases (this I heard at a demo at Leagacy Audio factor years ago, when the guy demoing the Whispers cranked them up- when I explained what we were hearing, he didn't believe me at first until I got him to get a scope of the back room and found the inductor that was "collapsing at the high signal level.

The peak power/current ratings are based at 5% distortion; what one really has to be concerned with is how far up the BH curve a given inductor goes; the more turns, the lower the maximum current you should use them at. I've always had rather good good results for parts under 5 mH.

The other issue is DCR versus inductance, and the resulting insertion loss in the crossover from the DCR... This has to be controlled, especially with low Z driver loads.

And cost has to be considered, particularly for midrange performance level speaker designs- a SuperQ 2.5mH inductor with AWG14 conductor is about $20, with a DCR of 0.114 while the AWG12 foil inductor is $72, with a 0.345 ohm DCR.

[JonMarsh]

Parts ordered from audiohobby. Getting them by end of month, so then the V1.4 xovers will be built and evaluated.

I'm probably going to try ordering direct from Erse this time, instead of PE, because they have lower DCR AWG14 versions. May try some of their foil coils, too. Also will be looking at the Obligattos film caps through Parts Connexion for hopefully some cost/performance optimization, though I have Clarity MR's for the next tweeter build...

[TheWaveCarver]

Have you ever measured one? And in comparison to what other inductors? At what power level? Any test data you have would be appreciated, as my own tests show that that they have pretty dang good performance in the range up to 3kHz; I do usually only use them in LP networks below 1 kHz.

It's also important to be specific about cored inductor, becuase performance varies considerably based on core material; ferrite bobbin cores are pretty OK at low levels, but when you get to where they start to saturate, they do so very suddenly and hard- liked amplifier clipping, in some cases (this I heard at a demo at Leagacy Audio factor years ago, when the guy demoing the Whispers cranked them up- when I explained what we were hearing, he didn't believe me at first until I got him to get a scope of the back room and found the inductor that was "collapsing at the high signal level.

The peak power/current ratings are based at 5% distortion; what one really has to be concerned with is how far up the BH curve a given inductor goes; the more turns, the lower the maximum current you should use them at. I've always had rather good good results for parts under 5 mH.

The other issue is DCR versus inductance, and the resulting insertion loss in the crossover from the DCR... This has to be controlled, especially with low Z driver loads.

And cost has to be considered, particularly for midrange performance level speaker designs- a SuperQ 2.5mH inductor with AWG14 conductor is about $20, with a DCR of 0.114 while the AWG12 foil inductor is $72, with a 0.345 ohm DCR.

Interesting. I have no tests to back up my claim, just what I've read online. Seems like most guides just tell you to avoid anything but air core inductors to prevent others from just picking ANY inductor that matches their specs. It seems that depending on the core, certain types may cause potential issues. Your explanation on the ferrite bobbin cores was insightful (Along with the story). What did it sound like exactly when the Whispers were cranked? Quick clipping?

[JonMarsh]

It was a bass transient both on synthesizer and drum, that at first they thought was amplifier clipping (they were controlling levels, and it wasn't turned up beyond what is usually OK- and yes, it sounded like clipping, becuase there was a sort of snap transient coming through the woofers that shouldn't have been there.

Magnetic materials have greatly varying characteristics; among other things in my day job, I design power conversion equipment, including the transformers and inductors. The Erse SuperQ inductors have been used in several designs, including the Wavecor Ardents. A properly designed air core inductor will certainly be superior to a poorly designed solid core inductor, but for LF applications it will be VERY large and expensive. Possibly a "statement" class speaker would justify going with AWG 10 or better inductors, or paralleling AWG12 inductors (two 5mH AWG12 inductors could be paralleled to create a 2.5mH inductor with lower DCR) but that is pretty rare.... Especially with copper prices the last several years!

[kimmosto]

..hear about the upcoming option...

Power response and DI calculation is now improved in version 0.1.4.9. See changelog.
There is no separate option for half space (IB) constructions. Just load measurement data to 0-90 deg sector. Shape and tilt of power response and DI curves will be okay with actual IB. Levels have 3 dB offset but that's just theoretical issue.
Full space constructions should be measured to 0...180 deg sector in order to get correct shape and tilt and level in power response and DI. Software cannot skip that reality.

[JonMarsh]

Thanks again! Will go online on both systems for the update this morning!

The last week at work has been 5:30AM to 7:30PM door to door, so no spare time to speak of- I've really been looking forward to the weekend!

[Steve Manning]

I'm probably going to try ordering direct from Erse this time, instead of PE, because they have lower DCR AWG14 versions. May try some of their foil coils, too. Also will be looking at the Obligattos film caps through Parts Connexion for hopefully some cost/performance optimization, though I have Clarity MR's for the next tweeter build...

Going to be interested in what you think of the Obligattos .......

[JonMarsh]

Going to be interested in what you think of the Obligattos .......

Well, I'm curious, too, Steve, but I think using them in this design is appropriate - I think of the Minerva as a upper end bang for the buck system, not an all out statement system, more a NatalieP on serious 'roids, and all bulked up on the bottom end and what not...

Of course, when we see the final tab for the two pairs we're building, I may have to revisit that statement... :roll:


I loaded up the update from Kimmo to VituixCAD, and took another look at things- the midrange level being the only thing that sticks about a bit, and changing the input resistor to that network from 9.1 to 10 ohms seems to take care of that as regards the power response slope, so without further adieu or discussion, we present the wholly options 1.4A crossover suggestion:




I suggest downloading this to disk, unless your browser will display 2400 pixels horizontally on your current display, and printing. (mine does easily, but I'm cheating with a Dell 5K display... it's disgusting how many Dell displays I've bought in the last few years, and one Dell laptop recently that came with a 4K display built in, but that's something Dell seems to know how to do fairly well...)

Today I hope to update my Eagle Schematic with the reference/component designator sequencing that Ergo has been using on his LspCAD files, for consistency and clarity when we contrast and compare and disseminate documentation to others.

While I've been working here I have my one Minerva with the old 1.0 crossover with the tweeter tweak playing- Edie Brickell, "What I am", and now Spyro Gyra "East River Blues"- heck, it's pretty dang good even at this point, but I do believe the final ones will be even better, and I thank everyone for the collaboration to date on this project.

Better go order some parts, too!

[ergo]

Thanks Kimmo - update installed.

Jon, my updated partlist for v1.4 as I ordered it is here just in case. I did order some extra resistor values so I can also adjust mid resistor accordingly.

I've been checking out the new Dell monitor models for few months now, trying to come up with good justification why would I need one.... now I have a reason - to be able to look at Jon's screenshots 1:1

I did discover though that LspCAD hits window size limits with 1920x1200 already (especially for clone windows). So another "+" for VituixCAD

[JonMarsh]

Yeah, I've noticed that for a while with LspCAD, too. My older 2010 MacPro is the official "windows workstation" at casa de Juan, and there I have a 25" Dell 2560X1440 display, works very nice for Windows because Windows really has a mishmash of graphics API and it's hit or miss whether a given program will work properly with Retina style displays- for example, that Dell 4K XPS15 notebook usually gets run in 1920x1080, or in 2560x1440 on an external monitor, because the two key programs I bought it for, Audio Precision AP500, and SIMPLIS/Simetrix, don't work properly yet with HiDPI displays due to how they implement some of the UI. Vituix is OK, though. LspCAD, not so optimum.

Something to keep in mind about some of these resistors is power dissipation, if you crank things up- particularly for R2, R1, given the area under the curve they're working in. I often double up on the resistors, and double the value, as I did for the Ardent.

Today I ordered Obligatto film caps and Mundorf resistors, in this case through Parts Connexion in Canada, because they are running a 20% off sale on film caps this month, and their "normal" price for the Mundorf resistors is very close to the Hobby price, especially considering when you toss in the difference in shipping.

I'll probably put together one of my normal Number's BOMs, as you've got some tricky stuff setup with embedded links and what not in yours- after a few minutes messing around with it, I said to myself, "Ok Jon, put the keyboard back on the table, close the program, and just back away from this one...." :W

[Steve Manning]

Well we've started into what Jon would call the "fiddley bits" stage ....... Most of the major construction is done at this point, so it's now onto things like sanding, appling sanding sealer, fixing voids, etc. One of my favorite parts of working with wood is when you put some kind of finish on it and it all of a sudden comes alive with color. Just putting a little shellac on the first set of sides made a huge difference in the way it looks. I think our color choice changes will look pretty good Jon. :T

Got the inserts in for the circuit boards so got those installed ....





With wanting to make sure that I don't have an epoxy squeeze out problem and mess up the aluminum trim when the sides get attached, I've opted to go lite on the amount of epoxy and add some pocket hole screws to take up the slack .....



First set of sides to get a coat of shellac .....

[ergo]

Sorry about that Jon - not intentional. That was Windows trying to be helpful - I copied the part names from website to excel and those came with link attached 'automagically'. I did a copy and 'paste values only' to a new sheet here. That one should be less nerving.

Great progress Steve. Not far from getting the boxes to have 'volume'.

[JonMarsh]

Sorry about that Jon - not intentional. That was Windows trying to be helpful -


Great progress Steve. Not far from getting the boxes to have 'volume'.

No worries, mate- I just backed away from the computer and all was well! But I'll take a peek at your other copy, too. The unnerving thing was that when I had you last one download, and "cleared contents" on one of those cells that had a part link, then tried to type in something else, it would still start up the browser and go out to HobbyHiFi... unnerving! Like the dead will rise... zombie apocalypse Excel Cells.

Now, there's two kinds of volume we need to achieve...

the one deriving from an enclosed space (check... Steve is getting close...)

And the one driving from the amount of SPL generated from some good music playing through that enclosed space!

[JonMarsh]

Well we've started into what Jon would call the "fiddley bits" stage ....... Most of the major construction is done at this point, so it's now onto things like sanding, appling sanding sealer, fixing voids, etc. One of my favorite parts of working with wood is when you put some kind of finish on it and it all of a sudden comes alive with color. Just putting a little shellac on the first set of sides made a huge difference in the way it looks. I think our color choice changes will look pretty good Jon. :T

Got the inserts in for the circuit boards so got those installed ....

[ATTACH=CONFIG]25690[/ATTACH]

[ATTACH=CONFIG]25691[/ATTACH]

With wanting to make sure that I don't have an epoxy squeeze out problem and mess up the aluminum trim when the sides get attached, I've opted to go lite on the amount of epoxy and add some pocket hole screws to take up the slack .....

[ATTACH=CONFIG]25692[/ATTACH]

First set of sides to get a coat of shellac .....

[ATTACH=CONFIG]25693[/ATTACH]

[ATTACH=CONFIG]25694[/ATTACH]

Seriously looking better and better! :T

With work like this, everyone else is going to get sick of this thread and the mutual admiration society we have going here!

[TEK]

If it is some comfort, I to think this looks great - and I do not consider myself a insider in this build ;-)