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

[Fdas]

When will listening impressions happen on the 'final' product?

[Steve Manning]

I'm hoping a few weeks for the pair I have. I have a good chunk of the second crossover board done and the some finishing work on the cabinets to do. Budget constraints had put things on hold for a while, though at this point I have most everything I need to finish.

I'm pretty sure Jon's are a ways out due to all the stuff he has going on at the moment.

[JonMarsh]

I'm pretty sure Jon's are a ways out due to all the stuff he has going on at the moment.

Sadly, that's very true- I'm starting to get the fall out from my Danish colleague that quit and re-located back to southern CA... stuff getting dumped in my lap with increased urgency, and boss wanting updates while he's in Europe this week. Fixing other peoples problems and lack of planning and execution.

Oh well, I figure just 15 more months to go...

Another long delayed issue- have an appointment tomorrow with orthopedics about possible hip joint replacement surgery. GF has been bionic on both legs for some time- it's been an issue for me for several years. Helped her get through the process and rehab. Figure I need to do this while still employed. Not looking forward to it, having seen up close and personal what the rehabilitation process looks like. OTOH, the functional improvement is substantial.

Cross fingers...

[Alaric]

I think it's very much dependent on the recipient. My Pop had both hip joints replaced and he said it was a breeze. My ex had a partial knee replacement and it was an ordeal. If I ever need a leg joint replacement I'm hoping the 16 leg surgeries I've already had will have prepared me. As much as one can really be prepared for that sort of thing, anyway.

[TEK]

I think it's very much dependent on the recipient. My Pop had both hip joints replaced and he said it was a breeze. My ex had a partial knee replacement and it was an ordeal. If I ever need a leg joint replacement I'm hoping the 16 leg surgeries I've already had will have prepared me. As much as one can really be prepared for that sort of thing, anyway.

My Pop? What does that refer to?
16 leg surgeries?:blink:

[Alaric]

My Pop? What does that refer to?
16 leg surgeries?:blink:

My father, I call him Pop. I got hit by a car while riding a motorcycle, years ago, and had 15 operations to put my left leg (somewhat) back together, and had a screw put in my right ankle 10 or 11 years after that.

[Caisa]

Hey guys,

I am thinking about building a Minerva like floorstanding speaker with the new C18EN002/A coax but different woofer. Is the x-over layout confirmed to work with the new version of the SEAS coax?

Did anybody made a in depth comparison? I talked (better wrote) with Troels Gravesen and he told me that he had trouble to get a good sound out of the coax and he did not recommend to use it. Now I am a little bit doubtful because the drivers are not beeing very cheap.

Furthermore I will not build a whole passive x-over network, but using a 2 channel DSP. This approach follwos the SEAS KingRO4Y.

The purpose of this passive crossover is to get a proper band limiting of the midrange and tweeter, and also make sure that they have a good phase tracking, so that they are perceived as a single unit. The EQ is easier and better to do in the DSP.

Crossing to the woofer will also be active between 200-300Hz.

I am not a x-over design guru as Jon and really appreciate his work. Build his Modula MTM few years ago, very impressive! Unfortunately I do not now, wich part of his x-over network is best to keep passive, and which parts are for EQing and can be omitted, or better be done active via DSP. Any advice is highly appreciated.

Thanks in advance and sorry for some curious wording, I am not a native speaker.... ;-)

Stephan

[Caisa]

Double post....

[Steve Manning]

Hey guys,

I am thinking about building a Minerva like floorstanding speaker with the new C18EN002/A coax but different woofer. Is the x-over layout confirmed to work with the new version of the SEAS coax?

Did anybody made a in depth comparison? I talked (better wrote) with Troels Gravesen and he told me that he had trouble to get a good sound out of the coax and he did not recommend to use it. Now I am a little bit doubtful because the drivers are not beeing very cheap.

Furthermore I will not build a whole passive x-over network, but using a 2 channel DSP. This approach follwos the SEAS KingRO4Y.



Crossing to the woofer will also be active between 200-300Hz.

I am not a x-over design guru as Jon and really appreciate his work. Build his Modula MTM few years ago, very impressive! Unfortunately I do not now, wich part of his x-over network is best to keep passive, and which parts are for EQing and can be omitted, or better be done active via DSP. Any advice is highly appreciated.

Thanks in advance and sorry for some curious wording, I am not a native speaker.... ;-)

Stephan

Hi Stephan,

I'll answer what I can for you, though Jon is the man for detailed questions on the crossover stuff, though his free time is pretty much non-existent these days.

We have not confirmed the new version of the coax driver. By all appearances the specs look identical and should work just fine.

I also read that Troels had some issues with the coax. Apparently Jon has a few more tricks up his sleeve and the results have been very good.

As for going with a different woofer and using active for part of the network .... I can imagine you would be talking a fairly major redesign of the crossover in general. Again Jon's the man for that question. Do you have a particular reason for going the route you have described?

Steve

[Steve Manning]

Since we are here in this thread, here's a few updated pictures of things.

Both crossover boards are complete and starting to go in the stands.








Cabinet wiring is also going on with the first cabinet. I did some additional work with the the fit up of the aluminum trim, since I was not completely happy with it. This required some additional painting and top coat rework as a result. The second cabinet is still in the middle of that rework.

[Alaric]

After hanging around the 'Guide for a smidge over 10 years I've seen a lot of crossover pictures. Yours are outstanding. I've seen some that looked like a Radio Shack blew up. LOL

[Steve Manning]

Thanks Lee, hopefully mine don't blow up when I turn on the power.

[ergo]

These look very neat indeed. Nice job.

Crossovers and PCB design is interesting. People will usually prefer nice tidy parallel lines / components etc. but in this case technically it is often much better to put coils at different angles by purpose. Not run parallel wires and so on. So sometimes a ratnest type of 3D wire and component mesh works well while a nice and tidy PCB will oscillate as hell. Makes this hobby that much more interesting.

***

In theory one can replicate the passive xover also in DSP - I copied the 'transfer responses' of the Minerva filter below (VituixCAD limits the range so I sort of zoomed in on second one to capture the mid range notch).
If the DSP you are planning might allow this type of transfer curves then it is doable.

[Caisa]

Hi Steve, ergo,

thanks for your help. I first read about the healthy issues of Jon's GF yesterday ... Sad to hear such things. Jon, if you read this and have time for a reply regarding the crossover I would be happy but there are more important things on earth than speaker building.... I wish you and your GF all the best!

Steve, the reason to go active, at least in parts is because I already have the DSP in my setup. Flattening the speaker response and filtering of the room is a lot easier using a DSP. Nevertheless, I will do the crossing of the coax unit (midrange and tweeter) passive like in the minerva, just try to do the equalizing part digital. I think that should be possible but calculating the right filters is still a bit tricky. The woofers will be AT 10C77 which should do fine. The more important part for me is the coax unit where I will to copy Jon's take on the crossover.

Ergo, the transfer function you posted is the whole circuit incl. the band limiting circuits (highpass, lowpass) if the drivers right? Can you help identifing the parts if the whole crossover which are not responsible for high or lowpass but for the EQ to glatten the overall response?

Thanks and greetings,

Stephan

[BobEllis]

Stephan, my experience with changing the Wavecor Ardent to the new model woofer was that despite appearances, Jon's crossover designs use the minimum number of parts to get the job done. That means there are few/no parts dedicated to just high pass or response smoothing. Even changing what appeared to be the padding resistors altered the response significantly. I'd considered a mixed active/passive setup for which Jon suggested a passive mid/tweeter XO and active mid/woofer XO. I wasn't able to pull what appeared to be the high pass parts of the crossover without destroying the mid/tweeter crossover performance.

My suggestion is build as designed or use a fully active crossover with the transfer functions provided. Be forewarned, though, that a dsp based solution may not nearly as good as a passive with a good DAC. I suspect the resolution of the Minervas is good enough to differentiate between various electronics. With my Ardents, my girlfriend (whose music source was a B*** Wave Radio before me) notices whether I'm using my Oppo BDP-103's analog outs or a Cambridge 851D. That's without prompting - "Ah, you've got the good DAC going, it's so much clearer." With my previous speakers (Seas Excel based) I couldn't hear a difference with a miniDSP doing bass bin crossover duties. Now it is totally unacceptable for anything other than subwoofer EQ.

[Caisa]

Dear Bob,

thanks for your reply. If the mix of passive/active will not work for the coax unit, I will try the passive xo version as presented and compare it to a fully active setup which I try to emulate with the transfer functions. Either way, the woofer will be crossed and EQed active.

I am not a fanboy of the miniDSPs. But, my experiences with DSP equipped power Amp's, or DAC/Pre's (as you like) from the german manufacturer "Hifiakademie" are very positive. Besides the very good DSP technology they are also famous for their digital poweramps. They are also involved in the active speaker designs like the "German Physics Unicorn".

BR
Stephan

[ergo]

Hi Stephan,

If you send me a private message with your e-mail I'll send a link to the Minerva project file for VituixCAD. VCAD is freeware nowadays, so you can open the project files and play around with exporting the transfer functions or even trying to create active DSP crossover. VCAD has all the basic active modules you'd expect in a DSP available. The project is based on my version of the box - it's front panel is taller but the speaker spacing is same and Seas being a coax - so the physical setup of tweeter/mid is anyhow the same.... though the older version which presumably is still very similar.

[Caisa]

PM sent.... THX!

[meb46]

Steve - Is there any such this as "Crossover Artwork"? Awesomely made, and great attention to detail... I can only hope for half as good as this

[Steve Manning]

Steve - Is there any such this as "Crossover Artwork"? Awesomely made, and great attention to detail... I can only hope for half as good as this

Thanks Mike ..... I'm sure yours will be every bit as good, looking forward to seeing them.

[Steve Manning]

The end of the road .....

Well I finally made it to the end of the road ...... both cabinets are finished and making music. Here are a few pictures of the finishing steps.


Wiring pig tails for drivers.



Cabinets wired and waiting for drivers.



Drivers installed.



PR and connectors.



First cabinet done waiting for move into listen room.

[Steve Manning]

Moving everything into place ......

Getting stands set into position. Starting with the same location as my 1071's and go from there.





Cabinets and stands together.

[Carl V]

WOW, looks great....but yer killing us.
Vicariously we want to hear & appreciate
this ambitious design & construction.;x(

Throw us a bone fer cryin out loud8)

[ergo]

Congrats Steve, getting out of the tunnel into the light finally. Hope you do like the sound - though I do understand that it always takes at least a few days of long listening to get used to a new set of speakers and start to tell whats good etc.

I still enjoy mine. Got some evaluations done also between the NAC C390DD DAC/pre/amp combo versus Soekris DIY DAC + DIY Bruno Putzey's Balanced Preamp + DIY B&O ICE powereramp I finished recently. The Minerva's sure are revealing enough to be able to tell the differences

[cochinada]

Your attention to detail is simply outstanding! Have you ever consider doing this for a living?

I couldn't help noticing that the mid/tweeter seems to be a little over recessed by perhaps 0,23mm or so . Am I right or is it just an illusion from the pictures? I'm being incredibly picky of course but taking into consideration your level or perfection I'm sure if that was the case you noticed it as well. In my case the subwoofers are almost 1 mm too deep.

[Steve Manning]

OK Carl, here's a bone for ya. :W

Now that I have them in a reasonable location in the room and had a little time to listen, it's safe to say in typical Jon fashion, another killer design. These have very tight deep base and a nice detailed presentation, everything blends very well together. Like Ergo said, it takes a little while to come to terms with what the differences are over what came before. One thing to note, these things like power, little flea watt amps will not cut it. I can imagine a pair Hypex mono blocks making these things sing.

Joaquim as for the the perceived recess, I think it's the low res picture, at least to the finger the drivers are pretty flush. Not something I worried about enough to pull out a set of calipers on anyway. By the way the business thing is under investigation, thanks for thinking they are worth selling.

All in all, it's certainly a design that is well worth building as it can certainly be done without doing all of the translam work that we did for this version which would reduce time and cost.

[5th element]

Wow it's nice to see these finally getting there. For some reason I thought they already had!

Compared to the 1071s I'd expect these to do a few things quite a bit better than they.

[Steve Manning]

Hey Matt .... financial considerations put things on hold on the crossovers for a while. That and I'm a picky SOB and was not happy with some cosmetic issues that have been resolved.

As compared to the 1071's your right, overall this is a better speaker. Though I think I would give a nod to the 1071's as far as the tweeter goes, I'd say maybe a little more detail in the top end. I need some more listening though to make that final call. The Minerva's beat the pants out the 1071's in low end and mid bass punch though, as well as mid-range integration.

[BobEllis]

Hey Steve, those look great and it sounds like you’re happy with them. I accidentally hit the laugh button when my phone slipped out of my hand, please don’t think it was intended. Can’t figure out how to undo that.

[Steve Manning]

Thanks Bob .... no worries I would not have even noticed it had you not said anything.

[JonMarsh]

Hello Guys,

Steve has been updating me regularly with his progress and a few questions now and then; it's really great to see his pictures of the final assembly and installed in his listening room.

I've got all the pieces on hand to finish my pair, but I swear, the last year+ feels more like the phrase "Life Interrupted", which has been used by both a book and a TV comedy movie, both with very different topics, but the basic concept is pretty clear to anyone...

Mine are going to be the "monitors" for my eventual music playing and recording area, probably part of a family room in the future. I'm having to play a long game here, as realization of this is now probably at least two years away. (I guess long game is a relative term- I'm still a bit of an instant gratification guy normally, but these days I have a lot of banked deferred gratification).

This has been a rewarding project, especially with the three way collaboration with Steve and Ergo. I've been trying to encourage a similar approach at work, and that is working very well for me and one of my colleagues based in Toronto, but unfortunately others have yet to pick up on that...

I've only heard the one table saw prototype, with an initial build test crossover, which is brighter and not quite as well integrated, but it did seem to do what I expected,







30 degree off axis




45 degree off axis





And the final version of the crossover with the last set of measurement data sims very well, I think, incorporating the voicing concepts we've discussed else where on the forum.




Interesting side note, yes, this crossover uses a partial elliptic filter, and this last week I interviewed Jason Caudra for a potential AE manager position at our company- he is one of the earliest experimenters I know of using that approach for speaker crossovers, and pre-dates the AES paper on the topic.

http://www.mariobon.com/Glossario/___Filtri/Filtri_ellittici.pdf

Jason is a nice guy, and unlike most of the candidates I've interviewed, even fairly knowledgeable about the real dope for LLC multi-resonant converters. (one of my acid tests in interviews...)


So, yeah, as one of my colleagues in Boston would say, in his texting vernacular, "ANTICIPASHUN!"


But this holiday is going to be spent working on a crash project for work, another collaboration with my colleague in Toronto for a short fuse commercial opportunity we just can't pass up, and then next Monday on the 27 I go in early in the AM for a replacement hip joint surgery on the right side. It's been bothering me since 2010 and has been bone on bone for a number of years. OTOH, the left one looks practically factory fresh on the films, so this should be a big quality of life/functionality improvement. I'll be off on medical leave of absence for three weeks, so I can catch up with some stuff here and in the audio world... possibly. We'll see... :W

[Carl V]

Good luck with all your Projects
& Good luck with the 3 weeks
of HIP surgery recovery. I recall you
talking about Back injury/recovery many years
ago....causation or correlation or just bad luck?

[csmielke]

Jon,
Happy Thanksgiving and best of luck with the surgery on Monday as well as the recovery period on the back end.
Chris

[JonMarsh]

Good luck with all your Projects
& Good luck with the 3 weeks
of HIP surgery recovery. I recall you
talking about Back injury/recovery many years
ago....causation or correlation or just bad luck?

Not really related- that was a herniated L5-L6 disk, due to a misspent youth hauling around a Hammond B3 organ. These days I'm much more sensible, and my KeyB III organ, which is quite a bit more flexible and complete than my old B3 (for one thing, it has tone samples of three generations of B3's) is only about 50lb.




I think this is just being right handed, I tend to favor putting the work on the right side. I helped GF through two hip replacements, but being an amateur competitive runner, (with about a dozen placing medals for her age group of women in local races from back in the day) she had it coming, given all the high impact stuff this involves. I'm a hiker, but more an elliptical trainer kind of guy for exercise... The left hip looks fine on the X-Rays

[JonMarsh]

Jon,
Happy Thanksgiving and best of luck with the surgery on Monday as well as the recovery period on the back end.
Chris

Thank you very much, Chris- appreciate the well wishes!

I have a pretty good idea of what I'm getting into, so I'm looking forward to 3-6 weeks out, but not the first two weeks at all! :W

But it's definitely been a growth experience getting ready for it, even had two echo cardiograms, one in stress test mode, one resting- but it all looks good.