My first project is a 4 way speaker...

[Steve Manning]

Until now I believe all votes are for the BB which is also my inclining. With my current speakers I had exactly the same problem and that is why I wasn't happy at all with the painter.

I think most painters do not have experience with mdf ..... the guy that did mine was used to painting cars and I don't think he will mess with mdf ever again! If you can find someone that knows the tricks to sealing it I think your golden. I plan on trying painting again after finding out how Wilson Audio does it, check out their videos.

[cochinada]

If you are only needing to cover the top plate, a wrap would be pretty simple. If you are thinking of doing the entire cabinet, then yes, it would be very complex and time consuming.

The tricky pieces are just the top and the bottom. Nothing else.

[cochinada]

I think most painters do not have experience with mdf ..... the guy that did mine was used to painting cars and I don't think he will mess with mdf ever again! If you can find someone that knows the tricks to sealing it I think your golden. I plan on trying painting again after finding out how Wilson Audio does it, check out their videos.

Yes, the guy that painted mine is also a car painter. Talk about coincidences...

About measuring gear... What do you guys say about Omimic vs. UMM-6 USB Measurement Microphone? The last one costs less than half and they say it works well with REW which is freeware off course but I don't remember ever using it except once long time ago.
And what about this thing? Is it a must or redundant? Don't forget that I'm on a budget. :roll:

[Face]

Omnimic comes with better software, without a doubt.

[Paul W]

Make sure you get a calibration file unique to the individual mic you purchase. Do not settle for a generic cal file. Behringer ECM8000 with a specific cal is doable in the states for less than $100...don't know about Portugal.

[cochinada]

Omnimic comes with better software, without a doubt.

Better in what sense? More accurate? More Powerful?

Make sure you get a calibration file unique to the individual mic you purchase. Do not settle for a generic cal file. Behringer ECM8000 with a specific cal is doable in the states for less than $100...don't know about Portugal.

This Behringer here costs about 60€ plus shipping but then what about the SW and where do I connect the mic?

[cochinada]

I was not happy with the previous crossover points as I mentioned so gave it another attempt. I believe I was able to push the LP lower closer to 350Hz as my initial goal as well as the band pass, keeping the higher xo at around 1700Hz.
So, here are the results:

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The one that is making me most upset is the Impedance. How can I increase it without messing the SPL, for instance?

[5th element]

Those impedance plots look wrong. The tweeter one has a fairly stereotypical shape, but the bass and midrange? The reason why the impedance from 200Hz and up is so low is because you've got the driver associated with the blue trace running in parallel with everything else up to 20k. Why is this so? If the blue trace is for the mid drivers then where is the low pass? This is vital in causing the impedance to rise as frequency rises, but even so you're going to end up with an impedance minimum throughout the midrange.

What does your crossover look like?

[cochinada]

Those impedance plots look wrong. The tweeter one has a fairly stereotypical shape, but the bass and midrange? The reason why the impedance from 200Hz and up is so low is because you've got the driver associated with the blue trace running in parallel with everything else up to 20k. Why is this so? If the blue trace is for the mid drivers then where is the low pass? This is vital in causing the impedance to rise as frequency rises, but even so you're going to end up with an impedance minimum throughout the midrange.

What does your crossover look like?

Sorry I forgot to attach the crossover yesterday. Here it is:

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The blue trace is for D31 and D32 and the green for the bigger woofers.

Since I'm gonna use 4 upper bass woofers of 8" (D21 to D24) paired in twos I thought about connecting them in series in each box and each box in parallel. I could do the other way around, that is, each pair in parallel and both boxes in series but I chosen the first option. What do you think? Where is my mistake?

[Paul W]

This Behringer here costs about 60€ plus shipping but then what about the SW and where do I connect the mic?

The mic is connected to a small preamp which drives the sound card in your PC. Preamp must also provide phantom power to the mic...Behringer and others make them. There are several freeware measurement programs available...as they say, Google is your friend.

[5th element]

Well there's your problem you have a zobel connected AFTER the low pass elements in the midrange network. This is equalising the impedance flat. If you're going to use a zobel you need to place it across the drivers terminals.

[cochinada]

The mic is connected to a small preamp which drives the sound card in your PC. Preamp must also provide phantom power to the mic...Behringer and others make them. There are several freeware measurement programs available...as they say, Google is your friend.

I see... So this would imply buying a preamp AND a sound card and they don't come cheap. At the end I would probably spend more money than with Omnimic. :roll:

Well there's your problem you have a zobel connected AFTER the low pass elements in the midrange network. This is equalising the impedance flat. If you're going to use a zobel you need to place it across the drivers terminals.

Are you talking about the branch with R=2.7 and L=220uF?

[cochinada]

After many requests I've redesigned the MTM and was able to make it deeper by 3cm. This is the before (left) and after (right):

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For simulating the volume necessary I used Jeff Bagby's Woofer Box Model and Circuit Designer but here I have some doubts. Namely, for 'Series R' should I use 034 (0.17 + 0.17) or what?

The result was this:

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I had to reduce a little the total volume as the ones with the sharpest eyes will notice. What do you guys think about it right now? Is it safe now?

Important! Please note that the crossover will have to be corrected because of a rookie mistake that 5th Element has just pointed me.

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[Paul W]

I see... So this would imply buying a preamp AND a sound card and they don't come cheap. At the end I would probably spend more money than with Omnimic.

Think I paid ~$50 for my preamp, but that was years ago. The sound card in your PC is likely quite adequate.

The key is using an accurately calibrated measurement system...inaccurate calibration produces a corresponding error in the result/your speaker.

[knowledgebass]

Most entry level usb musician soundcards have a built in preamp and ghost power. I bought mine 14 years ago.

[kevinm]

I might be missing something really obvious, but why not just use a USB mic? Sound Spectrum Labs sells 3rd party calibrated USB mics.

[cochinada]

Well, this chapter is over with. I've ordered Omnimic together with Dats V2. Unfortunately the Euro is at the lowest value vs. the USD over the last 10 years but I will consider this an investment. Major blow to my budget :cry:

[Hdale85]

I think it's funny you're planning a crazy 4-way speaker with a huge complicated CNC cut cabinet, and then talking about budget

[cochinada]

After many requests I've redesigned the MTM and was able to make it deeper by 3cm. This is the before (left) and after (right):

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After some thought and also discussing with a friend we come to the conclusion that the first box is probably better than the second. If we think of it the sound radiates more sideways than directly backwards because the magnet prevents that. OK I give that it will probably radiate in a 45º angle more or less to both sides. Perhaps I should make the enclosure more circular to the sides and just a tiny little bit deeper. What do you have to say about it?

[cochinada]

I guess from the absence of any comments that nobody has a clue then?

[---k---]

I think that it is probably theoretically debatable either way. To really answer, you probably need to build it and test it.

But, and I'm getting beyond my area of expertise here, with the crossover to the woofer, you're not really looking worried about the low end extension of the mid. I don't think having too big of a box hurts the mid. I would error on the side of too big.

[cochinada]

I think that it is probably theoretically debatable either way. To really answer, you probably need to build it and test it.

But, and I'm getting beyond my area of expertise here, with the crossover to the woofer, you're not really looking worried about the low end extension of the mid. I don't think having too big of a box hurts the mid. I would error on the side of too big.

I will use a bigger volume around 9l or so and the shape will be close to the first option but wider and a little deeper as well. I hope to be able to tune it using more or less fill. Thanks!

[Carl V]

I will use a bigger volume around 9l or so and the shape will be close to the first option but wider and a little deeper as well. I hope to be able to tune it using more or less fill. Thanks!

I am sure you are aware of back masking or having a solid boundary too close to the
midrange cone. "cupped hands..honky & peaky sound.
Also the taper is fine but it needs breathing room. Deeper is fine. The Sealed Volume
of a Midrange often times plays a part in the Acoustic Roll Off of the driver.

[cochinada]

I am sure you are aware of back masking or having a solid boundary too close to the
midrange cone. "cupped hands..honky & peaky sound.
Also the taper is fine but it needs breathing room. Deeper is fine. The Sealed Volume
of a Midrange often times plays a part in the Acoustic Roll Off of the driver.

Yes. I think there is plenty of space in this case. The driver is really very small and this is about 9.3l (twice the original volume, deeper and wider).

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[cochinada]

Impedance now is a little better. I've also replaced the manufacturer curve responses of the 12W/8524 by the simulated responses on the respective cabinet getting a little closer to the real thing. Next I will do the same with the 8" drivers. Here, because the volume available is not as big as that, I'm considering the possibility of using a series capacitor. This is an old concept and my friend's B&W 801 for instance have a 1000uF before the big woofer and all I can say is that they sound wonderful. This new crossover was also created by him and I have just tuned it a little.

As I'm getting more used to VituixCAD I'm getting also more and more a fan of it and I highly recommend it:

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I've also seen that with this crossover topology is possible to raise the minimum impedance above 4 ohm at the expense of 2 or 3dB so it's all a compromise and I'm not too concerned about it any more.

[cochinada]

As it would be expected some differences between announced specs and measured specs. I just didn't expect some were so significant.

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One thing that pleases me is that both Scan Speak drivers have greater sensibility than announced.

[cochinada]

cochinada nice looking project, can't wait to see how it turns out. I did a translam project a few years ago and I would agree with knowledgebass with his suggestions if you are going to use baltic birch. I had splitting on my project like others have, so here is my two cents worth from what I learned, they may duplicate what knowledgebass has already said .......

* If you can I would use bamboo plywood, it's a lot more stable than baltic birch.
* Seal inside as well as the outside of the wood to get even moisture absorption.
* I would not use dowels to hold the layers together, it will constrain the plywood and not allow it to move.
* Do not glue the baffle in place, same reason as the dowels, float it with a gasket. Magico did that with their original Mini.

Steve

Hi Steve,

Somehow this post slipped through my eyes. I understood your first two tips but exactly how do you suggest to hold the layers together without dowels? Just using glue? And what about the baffle? Do you mean to screw it instead of gluing it?

[Steve Manning]

Hi Steve,

Somehow this post slipped through my eyes. I understood your first two tips but exactly how do you suggest to hold the layers together without dowels? Just using glue? And what about the baffle? Do you mean to screw it instead of gluing it?

Hi Cochinada,


Glue should be all you need ....... I used the holes for clamping and alignment when I was gluing the layers together, then removed the threaded rods.




As to the baffle question ....... I glued and doweled the baffle and back into place, which I think is where most of my trouble came from. You can see the holes in the pictures I posted. I found out from looking at some construction pictures of older Magico speakers, that they have an o-ring in the back of the baffle and back insert for sealing and then bolt the baffle and back together though the cabinet. This lets the cabinet float independent to the baffle, allowing the wood to move around as needed.







Steve

[cochinada]

Thank Steve. The first part with the rods is understood but I'm afraid you lost me on the Magico speakers. You will need some giant screws for attaching the baffle to the back of the speaker I would say unless I didn't understand the idea. Do you think you can find those pictures you mention?

[Steve Manning]

Thank Steve. The first part with the rods is understood but I'm afraid you lost me on the Magico speakers. You will need some giant screws for attaching the baffle to the back of the speaker I would say unless I didn't understand the idea. Do you think you can find those pictures you mention?

They use threaded rod and since their baffles are aluminum coming up with a thread hole is rather straight forward. Using wood, threaded inserts are easy to come by to do something similar. I'll look and see if I can find some pictures of what I'm talking about for you.

[Steve Manning]

I found some pictures of Magico's construction back when they were doing BB and aluminum. They are going all the way through the cabinet with threaded rod. I think something a little cleaner could be done, but you get the idea and you can see the o-ring on the back of the baffle for sealing.









I think you could also layout your driver cutouts such that you just use a threaded stud attached to the baffle and and have it run through the wood and attached a washer and nut by reaching through the driver cut outs, or a removable cabinet bottom.

[cochinada]

Wow! This is very complicated stuff. Do you know if they use these rods for the sake of stability and expansion of the 'wood' due to the translam building technique or is there something else (aside from the fact that being in aluminium the baffle couldn't be glued of course)?

[Steve Manning]

Wow! This is very complicated stuff. Do you know if they use these rods for the sake of stability and expansion of the 'wood' due to the translam building technique or is there something else (aside from the fact that being in aluminium the baffle couldn't be glued of course)?

I would suspect that it's just one way of attaching the baffle and being able to adjust the bolt tension as desired to track wood expansion and contraction, other than that I don't know.

[deewan]

Monitor Audio does a similar construction with threaded rods through the back of their PL line. I think the Monitor Audio design would be easier to duplicate.

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[5th element]

Monitor Audio does a similar construction with threaded rods through the back of their PL line. I think the Monitor Audio design would be easier to duplicate.

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Actually I really like this approach, allowing you to do removable baffles that can be decoupled by a layer of something squishy between the baffle and the cabinet hmm..

[Steve Manning]

Actually I really like this approach, allowing you to do removable baffles that can be decoupled by a layer of something squishy between the baffle and the cabinet hmm..

Makes it nice if you want to mount your drivers on the backside of the baffle as well.

[cochinada]

Some ideas:






I will most probably design my own supports (in fact they are already finished) and will choose between the Viablue or Trackaudio or even the Soundcare spikes.
One thing is settled: due to the weight of each speaker they will have four spikes that will of course have to be adjustable.

If anyone has any suggestions please come forward.

[Hdale85]

Wow those Viablue's are nice looking.

[---k---]

I like the look of the outriggers, but when I've gone looking for them they've been really really expensive. Recently, someone on PE Tech Talk recently posted a link to a metal fabricator who had standard off the shelf brackets for a reasonable price. He then added some of the big PE spikes to it and it made outriggers very similar to shown above. I thought I had book marked the site, but now can't find it on this computer. I thought the company had 'Uni' in the name, but my memory isn't working so well these days.

[Steve Manning]

I have the ViaBlue's on my Jensen's, very well made and they have a great load rating. I also found a place that sells them for about 1/2 of MSRP is, so that also helped in making my choice.

[cochinada]

Wow those Viablue's are nice looking.

Yes, I also find them very nice notwithstanding the Trackaudio ones.

I like the look of the outriggers, but when I've gone looking for them they've been really really expensive. Recently, someone on PE Tech Talk recently posted a link to a metal fabricator who had standard off the shelf brackets for a reasonable price. He then added some of the big PE spikes to it and it made outriggers very similar to shown above. I thought I had book marked the site, but now can't find it on this computer. I thought the company had 'Uni' in the name, but my memory isn't working so well these days.

Well, if you remember please share although I don't think it pays importing them from USA. I mean with the shipping, taxes and the devaluation of the Euro these days I probably have to order some custom made supports locally.

I have the ViaBlue's on my Jensen's, very well made and they have a great load rating. I also found a place that sells them for about 1/2 of MSRP is, so that also helped in making my choice.

Great! Then you are the one that is going to clarify some doubts I have .
One thing is not clear to me and it's the length of the threaded sticks. From the Viablue site they mention 15mm but with only half of it coming out of the spike I find this too short to provide a sturdy attachment. What do you say?
My other question is about the adjustment. Is it easy to do it using our bear hands without tools, even if we have a very heavy speaker like 360lbs?

BTW if you also want to share that place where they are sold at 1/2 price please do even if it is by PM.

[---k---]

Ah yes. I forgot you were in Europe.
I did go wandering through the PE forum hoping the thread would jump out at me, but it hasn't yet. If I do come across it again or find the bookmark on another computer, I'll post it. But, I think the big point might be that there might be some places that sell parts that look very similar and can be re-purposed into outriggers.

[Steve Manning]

Yes, I also find them very nice notwithstanding the Trackaudio ones.



Well, if you remember please share although I don't think it pays importing them from USA. I mean with the shipping, taxes and the devaluation of the Euro these days I probably have to order some custom made supports locally.



Great! Then you are the one that is going to clarify some doubts I have .
One thing is not clear to me and it's the length of the threaded sticks. From the Viablue site they mention 15mm but with only half of it coming out of the spike I find this too short to provide a sturdy attachment. What do you say?
My other question is about the adjustment. Is it easy to do it using our bear hands without tools, even if we have a very heavy speaker like 360lbs?

BTW if you also want to share that place where they are sold at 1/2 price please do even if it is by PM.

I just did a measurement and the threaded rod is just over 20 mm and looking at the online specs you can adjust that by another 5 mm. I have no problem taking them on and off by hand, but I do tip the cabinet to one side to do that rather than trying it with the cabinet flat, that way your not trying to move the entire cabinet.

Here is the link to the place I got them from http://www.avoutlet.com/index.php?di...roduct_id=1577, looks like they still have them for half of what I have seen them else where ... not sure if it would be worth it getting them sent to Europe or not, might be worth crunching the numbers at that price. They also carry Viablue cable stuff as well.

Besides the looks one of the main reasons I picked them, was their ability to support almost 450 lbs, everything else I looked at was around a 100 lbs for a set.

[Hdale85]

That price isn't bad at all!

[knowledgebass]

Ah yes. I forgot you were in Europe.
I did go wandering through the PE forum hoping the thread would jump out at me, but it hasn't yet. If I do come across it again or find the bookmark on another computer, I'll post it. But, I think the big point might be that there might be some places that sell parts that look very similar and can be re-purposed into outriggers.

I think I know the ones you're talking about because I looked into it and they proved more difficult to get than I imagined (all the way up in the wilds of Canada!).

I think this is the first post with these:

http://techtalk.parts-express.com/showthread.php?239095-need-outrigger-ideas&p=1934325#post1934325

Here's the most recent thread with them:

http://techtalk.parts-express.com/showthread.php?244407-An-Outrigger-Option&highlight=outrigger+feet

It's a part made by 8020 Inc. They appear to be available in different lengths. Also appear to be difficult to get the 8020 outside of US. What I really want is some of the extruded aluminum frame pieces to make a new tablesaw fence:

http://stores.ebay.com/8020-Inc-Garage-Sale/Extrusions-Fractional-T-Slot-/_i.html?_fsub=6479546&_sid=129537225&_trksid=p4634.c0.m322