Isiris evolution to Osiris Jr? Summary of Isiris build and new update

[meb46]

TEK - Time... a commodity many of us simply don't have... I spend endless nights in hotels thinking what I could do come the weekend, usually to be disappointed in having to attend social occasions. My wife isn't accepting... yet... of the excuse, "Sorry, cant make that birthday party on Saturday night for your best friend as I want to work on my speakers"... one day maybe

[Steve Manning]

Looking good Mike ..... what are you using for the sealer?

[JonMarsh]

TEK - Time... a commodity many of us simply don't have... I spend endless nights in hotels thinking what I could do come the weekend, usually to be disappointed in having to attend social occasions. My wife isn't accepting... yet... of the excuse, "Sorry, cant make that birthday party on Saturday night for your best friend as I want to work on my speakers"... one day maybe

To paraphrase an old commercial (maybe well before your time) "Wives are like that, yes they are..."

[sdl2112]

Looking good Mike...At this stage there is no reason to rush things. At least that's what I kept telling myself. The finishing part just takes time. Heck I just noticed I passed my 1 yr construction start date. Also funny...my girlfriend asked me this weekend how many more months till I finish...I was thinking to my self, she used the right unit of measure.:B Little does she know I'm already thinking of what's next.

[meb46]

I see we all have similar challenges

Steve - I'm using a local Singaporean Sealer and Lacquer Finish... one thing I have learnt, given the extreme humidity we have in Singapore, coupled with the difficulty of getting flammable products into Singapore, its just easier to use something tailored for the local market. Its a nitro-cellulose Sanding Sealer and compatible Lacquer Top Coat. Thus far the sealer has gone on well, and sands down to a chalky white finish. These are all Matte finish, as that is the look I am after. So far, surprisingly enough, dust and dirt has not been a problem during the application using a Fuji Mini-Mite 3. The build of the Sealer is also good, and I am just working through a flattening process to ensure each of the big surfaces are perfectly flat... harder said than done. Unlike Jon, the Mirka Sander I have is performing exceptionally well. The last coats that have gone down will have had about two weeks to harden, so I'm expecting some good results this coming weekend. All in all, I think each cabinet will have had about 15-20 thin coats of the sealer by the time I am looking at top coats. Its important they get seriously sealed to avoid the effects of humidity. I had noted in some areas, the application of the first light coat made some of the Bamboo Ply separate slightly. This has been corrected, and looks to be a subtle reaction between the Sealer Thinner and the Glue used on the Bamboo Ply. I just need to ensure the external surfaces are thoroughly sealed to avoid the nasty Singapore Humidity creeping in and destroying the finish over time. On that note, I have recently checked out the finish on my original ones, and have noticed some deterioration in some areas caused by humidity and the veneer underneath the painted finish... wont be making the same mistakes again! Unfortunately sourcing a decent epoxy spray on finish to use initially in Singapore was difficult, and I subsequently choose not to start with this...

[Steve Manning]

I see we all have similar challenges

Steve - I'm using a local Singaporean Sealer and Lacquer Finish... one thing I have learnt, given the extreme humidity we have in Singapore, coupled with the difficulty of getting flammable products into Singapore, its just easier to use something tailored for the local market. Its a nitro-cellulose Sanding Sealer and compatible Lacquer Top Coat. Thus far the sealer has gone on well, and sands down to a chalky white finish. These are all Matte finish, as that is the look I am after. So far, surprisingly enough, dust and dirt has not been a problem during the application using a Fuji Mini-Mite 3. The build of the Sealer is also good, and I am just working through a flattening process to ensure each of the big surfaces are perfectly flat... harder said than done. Unlike Jon, the Mirka Sander I have is performing exceptionally well. The last coats that have gone down will have had about two weeks to harden, so I'm expecting some good results this coming weekend. All in all, I think each cabinet will have had about 15-20 thin coats of the sealer by the time I am looking at top coats. Its important they get seriously sealed to avoid the effects of humidity. I had noted in some areas, the application of the first light coat made some of the Bamboo Ply separate slightly. This has been corrected, and looks to be a subtle reaction between the Sealer Thinner and the Glue used on the Bamboo Ply. I just need to ensure the external surfaces are thoroughly sealed to avoid the nasty Singapore Humidity creeping in and destroying the finish over time. On that note, I have recently checked out the finish on my original ones, and have noticed some deterioration in some areas caused by humidity and the veneer underneath the painted finish... wont be making the same mistakes again! Unfortunately sourcing a decent epoxy spray on finish to use initially in Singapore was difficult, and I subsequently choose not to start with this...

Despite the uphill battle with available finishing products and the environment, it sounds like your making good progress. I've been working on Jon to send the Mirka back and have it repaired/replaced ..... I think he just happened to get a bad unit with all the raving reviews I've seen on them.

I just became a member of the Fuji sprayer crowd ...... if I could get the lid on the gravity feed cup to stop leaking, I'll be very happy with it.

[meb46]

Steve,

The Gravity Gun Lids do need the seal replaced every couple of times you use it. I had purchased a number of spares including the Lid Seal, Pressurizing hose and directional valve. Replacing these every two - three sessions keeps things optimum. I also purchased a 1L Gravity Cup... which is great as it supplies enough paint for a single coat on both Subwoofer Cabinets... Downside is that it is so heavy to hold when full, I need two hands to hold it steady until its about half full.

Awesome machines, nearly fool proof!

[meb46]

Progress from this past weekend...

1. All Cabinets now have the base sealer coats excluding the bottom surfaces.
2. Still need some further filling (See Green Filler), should have this wrapped up and ready for recoat next weekend. I will probably aim to have the bottom surfaces also painted.
3. Have finally tracked down a spray booth to use for the top coats. Thus far I have just been spraying in the workshop... and actually turning out quite well despite the lack of dust control. Spray Booth is a good size with full dust extraction/control, so is perfect to use... aside from having to transport the cabinets to the other side of town.

[JonMarsh]

Well, if you have a truck around to match that boat you guys were refitting, should be no problem to transport the cabinet. And across town in Singapore is no trivial matter... I've spent some time there and have an idea of just what that means!

[CraigJ]

Well, if you have a truck around to match that boat you guys were refitting,

Wait, I thought the "Just a small vessel..... Cruiser for tripping around one of the Pacific Island Reefs" belonged to Mike?

Very nice job on the Osiris Jr., and thanks again for sharing another fantastic build with us.

Craig

[meb46]

Jon - Yep, not an easy task, but I have that sorted

Craig - Ha, not the case... I run the Shipyard that is building the vessel... it has some perks, very useful for building speakers!

Update - Finished designing the Cabinet Separator Plates, and Base Plate last night, these are away being machined at present, but will need some post-machining work as I got lazy with Solidworks last night and a screaming baby. The Separator Plates are 12mm Aluminum, and the base is 30mm Aluminum... most likely add a fair few kilos, but the are essential for the right finish.

At present, I am going to screw the separator plates to the cabinet Bottoms, and then apply an anti-slip foam matting to them. This will then sit on the cabinet below... given the weight of these things, this should rest fairly secure. My last build just had foam strips as anti slip, and they never move. It does mean that they are all just stacked together, not screwed/bolted together... but what will be pushing 350kgs+ when finished, I double anything will move.

Also purchased 15lb of Acousta-Stuf from Parts Express... this will be a trial an error process once the Subwoofer Cabinet is completed... however, keen to try something a little more scientific - Does anyone have a link to a step by step process of Cabinet Damping Tuning for Sealed Subwoofers?

This weekend plan is to finish the last of the filling, then spray on the last of the undercoats... then its time for Spray Booth and Top Coats. Thus far I have used about 12L of Sealer/Under Coat and 25L of Thinner... these things are thirsty!!

[cochinada]

Hi Mike, did I understand well? 350kg EACH speaker :E ???

Anyway if the cabinets are not coupled like you said don't you think that the smallest at the top could fall if someone inadvertently gives it a bump? I mean how much does it weight?
BTW they look awesome! :T

[meb46]

Joaquim - Yes, they are "fattening" up quickly. 350kg is a guesstimate at this stage, but there are a few key items that really push up the weight... 1. Sheer size and volume of Bamboo that has gone into them. The Subwoofer cabinets now require three people to lift them. I haven't put them on the scales yet, but the bottom cabinet is already well over 100kgs. 2. Aluminum Plate spacers and base add nearly 60kgs to each them. The Base Plate the speakers sit on is machined out of 35mm plate, and then the cabinet separators are 12mm plate. 3. The drivers - The AS250 is about 13kgs alone, and the 15" Subs are no feather weights. 4. The DS8.0 Amplifier mounted into the middle cabinet is nearly 6kgs, and I have no doubt the crossover design will add more than this again. 5. The Bitumen lining - 35kg's of Bitumen went into the cabinets - so all stacking up.

In terms of the cabinet stacking, with the anti-slip foam rubber matting, and the weight of the cabinets, i'm confident they wont move or topple. As I mentioned, my current ones don't move at all, and they are lighter, and sit only on some foam strips. Weight is our friend on this front...

[cochinada]

I'm wondering how will you manage to position them inside your house then... Comparing to yours, mine are simply feather weights at about 170kg each and even so I simply cannot move them anymore due to the spikes I'm using having very small plates that oppose sliding with all the weight they are supporting. This is something I wanted to ask as well. Will you use spikes under that heavy aluminum base? If so, which ones?

[Evil Twin]

I'm wondering how will you manage to position them inside your house then... Comparing to yours, mine are simply feather weights at about 170kg each and even so I simply cannot move them anymore due to the spikes I'm using having very small plates that oppose sliding with all the weight they are supporting. This is something I wanted to ask as well. Will you use spikes under that heavy aluminum base? If so, which ones?

Very relevant questions... these endeavors render my current project to be more on the scale of a light weight set of HT towers such as one might purchase at a local Home Theater emporium, like a PSB T2 tower, which could be carried out from the shop one under each arm, and do not even weigh what a Halcro DM10 preamplifier weighs in at.

I too, am wondering how an associate will move a pair of Eggleston Savoy Signatures out of his apartment in the coming months, much less from Munich to Singapore...

[TEK]

When it comes to get the right filling Jon habe explained a method that could be used before.
I do of course not remember how, but it is something about adding fill and measure the q until it changes around.
I'm sure Jon can chime in with some input on the matter...

[meb46]

At the moment, I will most likely assemble in place... i.e. Build from base upwards in my lounge and then disassemble completely when I need to move them. Not ideal, but the alternative is a pallet trolley!

No spikes, I'm using machined aluminium discs as feet... will post some photos once I have the base plates...


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[JonMarsh]

When it comes to get the right filling Jon habe explained a method that could be used before.
I do of course not remember how, but it is something about adding fill and measure the q until it changes around.
I'm sure Jon can chime in with some input on the matter...

It's simple, if you have an inexpensive tool like woofer tester 2, or even if you just have an amp and tone generator on PC and a small 50-100 ohm power resistor and volt meter. Basically, you want to keep adding stuffing and checking the frequency of the impedance peak- it will be going down as you add stuffing, until you hit the optimum point, at which adding more will cause it to go up! So back off to the optimum point. This gives the lowest sealed tuning for the size of enclosure and driver you have, and the highest damping. Now, if you have a large enclosure, and the Q the box is too low (below 0.5, which means the near field response at resonance is 6dB or more down from say, the 100 to 150 Hz level, then you don't want to go below a Q of 0.5, as that is critically damped. But this should have been figured out in the original design phase with Unibox, regarding the target volume.

[meb46]

Jon - I assume I should really do this for both the sealed Subwoofer Cabinet and the Sealed Woofer AS250 Cabinet? I haven't got the woofer tester, but seems like prime time to get it! Thanks!


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[Evil Twin]

For such an inexpensive device, it is quite useful- I also can testify to it's utility.

[meb46]

Top separator and base plates have arrived... heavy things... opted for a 32mm thick base plate and they top 30kg each. Now for drill/tap tonight and then will need to find a powder coater! The Mid separator plates should arrive today...



One area I will need to progress is the mounts for the crossover boards. At the moment, I will allow room in both the Mid and Top Cabinet for some crossovers, but will also need to incorporate a shield from the DS8.0 in the mid cabinet... um... Aluminum anyone?

Expecting to be laying down some top coats in the Spray Booth this week, coupled with trying a new Mirka 8" Pneumatic Sander... Big cabinets = Big sanders, well, more of a case of equipment evaluation for the factory!

[cochinada]

Well, considering all the care and detail you have put onto this project I would recommend copper for shielding

If you can't find it there you might get a copper chassis used on some vintage amplifiers or CD players for instance like Pioneer PD-91 and try to use it.

[JonMarsh]

Top separator and base plates have arrived... heavy things... opted for a 32mm thick base plate and they top 30kg each. Now for drill/tap tonight and then will need to find a powder coater! The Mid separator plates should arrive today...



One area I will need to progress is the mounts for the crossover boards. At the moment, I will allow room in both the Mid and Top Cabinet for some crossovers, but will also need to incorporate a shield from the DS8.0 in the mid cabinet... um... Aluminum anyone?

Expecting to be laying down some top coats in the Spray Booth this week, coupled with trying a new Mirka 8" Pneumatic Sander... Big cabinets = Big sanders, well, more of a case of equipment evaluation for the factory!

Some serious stuff, there, Mike! I wouldn't want to be your floor.... but then, I wouldn't want to be mine, either.

The biggest problem with using aluminum as an electrostatic shield plate is keeping a reliable electrical connection to it, to connect to ground or return, however you describe it. Aluminum oxidizes in the air, and becomes non-conductive over time. The same thing can happen to simple clamp on connections to it. It is possible, but not easy, to solder to aluminum. I'd consider copper sheet foil, in this situation. If you want to limit magnetic fields, then you need to consider mu-metal or similar magnetic shielding also. OTOH, distance works pretty well, and mounted in the back and base of the woofer cabinets, I wouldn't expect much trouble, especially as they have linear power supplies.

Otherwise, you could consider using a bit of Halcro technology in your layout...

[Steve Manning]

That's some crazy aluminum plate there Mike ...... I love it. :T Soft steel plate works well for shielding as well. We used it to keep stray magnet fields away from sensitive beam line components all the time.

[meb46]

Great progress over the last couple of days...

1. Separator and Base Plates now have Red-Oxide Undercoat on them and should get their first lick of top coat later today.
2. Cabinets are home from the Spray Booth... pretty happy with the off-gun finish, but they will require a polish once the lacquer hardens... will leave them a few weeks before starting this.
3. Tweeters test fitted - Fit perfectly... I love CNC!
4. Woofer has been Test fitted, now just waiting on suitable Machine Screws to retain them.
5. DS8.0 Test fitted, will need some slight modifications, but relatively good fit.

[Steve Manning]

Getting there Mike ..... looking very nice, always been a fan of the black and white contrast.

[cochinada]

Very nice indeed! :T
BTW, what slack did you consider for all the wholes? I mean the extra size needed for the drivers to fit, considering for instance the paint and the finishing.

[meb46]

Cochinada - Overall slack was about 1.5mm in radius in addition to the documented driver size. That said, I sealed the inside edge and limited the top coats to 2 - 3 layers, then masked them off. The Sealer/Lacquer I used has a tendency to be "high-build", so the type of material/paint you use will be a serious driving factor.

[wkhanna]

fricken amazing, Mike....

[meb46]

Welcome to the family...

Little Brother, meet Big Brother...



Subwoofers have been fired up and initial impressions exceedingly positive. The DS8.0 has power to burn and now begs the question... how do the neighbors "feel" about this?

Lots to progress with whilst I await the Lacquer to harden, Base and Separator plates are currently mid-paint, aiming to complete this weekend. Focus will move to the crossover in a few weeks, but in the mean time need to get my Speaker Tester to tune the Subwoofers.

[meb46]

Oh, did I mention... these are LARGE! Standing them next to the first generation puts things into perspective. Granted, they are still on their roller dollies which adds probably 100mm to their height, but they still tower well above me...

[scottvalentin]

Just wow. Unbelievable work Mike, those look beautiful (both of them!) and extremely impressive!

[cochinada]

Very impressive!

P.S. now you have a pair of monitors for the surround channels :B.
All you need is a center speaker and perhaps a subwoofer or two with some big 18" drives .:surround:

[Steve Manning]

Holy crap those are beasts ..... very nice Mike.

[Face]

Now you only need a matching center for a surround setup.

[Juhazi]

But is it a bit uncomfortable to sit on a kitchen/bar stool when listening?
Respect!

[TEK]

Little Brother, meet Big Brother...

[ATTACH=CONFIG]26648[/ATTACH]

Subwoofers have been fired up and initial impressions exceedingly positive. The DS8.0 has power to burn and now begs the question... how do the neighbors "feel" about this?

Lots to progress with whilst I await the Lacquer to harden, Base and Separator plates are currently mid-paint, aiming to complete this weekend. Focus will move to the crossover in a few weeks, but in the mean time need to get my Speaker Tester to tune the Subwoofers.

It would have been very cool to see a Ardent on the left of these!
You probably have to build a pair so that you can take the picture ;-)

[JonMarsh]

It would have been very cool to see a Ardent on the left of these!
You probably have to build a pair so that you can take the picture ;-)

Now that's an idea... after all, he may needs some additional surrounds if Mike does 7.1...

[5th element]

Boom boom shake the room...I hope your house is built on solid foundations!

[TEK]

I'n just waiting for the (ardent) center design so that I can build that :P

[TEK]

What caused you to not mount the sub amp in the bass cabinet?

[meb46]

TEK - Volume requirements and how much it would remove from the final Sub enclosure. It is something that would have been better in the one enclosure, but alas not to be. Part of the driver was to bring better bass to the design from my initial version, so I wasn't going to compromise anything on the bottom cabinet.

[JonMarsh]

Some measurement updates for MEB's Osiris project:

Here is the composite polar plot for the C168-6-990 taken with the target enclosure design front baffle- from 0 degrees to 60 degrees at 15 degree intervals.






Note that the roll off from 1 kHz downwards is due to both the combination of baffle step (6 dB impact) and the actual driver roll off due to T/S parameters. Note, the C168-6-990 is the only 6" class high performance midrange from Accuton that doesn't use damping ears on the cone (the small black circles); this is possible in all likelihood because it is driven around the periphery of the driver, not at the center with a conventional voice coil, and the spider itself is actually attached at the center rear of the cone.



The motor is a relatively slender combination of neodymium and steel wrapped around the periphery of the cone, and uses a very short titanium voice coil. This is how the driver achieves an acoustic origin in the mourning plane, so that no crossover gymnastics are necessary for phase alignment of the filter behavior.

At 7 kHz the primary breakup mode is quite high for a 6-1/2" class driver; one thing that is striking is how high the relative amplitude remains far off axis. This will require a carefully designed notch filter and choice of crossover frequencies to make this inaudible.

Which brings up the polar response- this is a driver with very pistonic behavior, and that alone poses upper limits on the usable off axis response due to phase cancellation from difference in arrival time as one goes off axis and higher in frequency. With the C168-6-990, I'm inclined to go with a crossover no higher than 2000-2200 Hz, and possibly as low as 1800Hz.



Good thing that the tweeter for this project is the very robust ScanSpeak 7140 - it will need some special attention in the presence regions, where what is effectively a short waveguide for the dome (most likely to increase off axis response at higher frequencies) also boosts output in the 3 - 8 kHz area.

[meb46]

Nice work Jon, assume you got a cabinet knocked up and used the baffle I sent you? Hope things fitted nicely...

[JonMarsh]

The C168 fit was a bit of an issue... a bit snug on this one, around the driver leads.


BTW, after working on this and agonizing over it, I sort of concluded that I don't really have the confidence I'd like to have in my synthesized AS250-8 model, so today I contacted Madisound and arranged a special order with them, for one driver, because they don't list it on the web site yet. (they said "Oops" over that- according to Adam, they intended to have it up there.

That's the good news, bad news it's probably as much as 30 days away. In the meantime I'll work on the crossover with what I have, then refine when I can measure in a suitable box with some real data.