desk tower 3way WIP.. (BlieSMa t25b + ETON 3-212 + Seas l26roy) + Hypex + PE boxes

[headshake]

TLDR: the speaker uses a laser cut baffle to hold the tweeter/mid on the smallest denovo box. The box uses edge moulding to form the 44mm radius. All of that sits on the top of a sub that is on a stand. …It is a stacked 3way will sit on each side of my desk.

I wanted a nice set of speakers for my desk and decided on gambling on myself rather than dropping coin on something that did not suit my needs. If I listen to loud music my ears will ring the rest of the day so I wanted to see what it was like to build something that was to my specs.

No speaker is perfect. I don’t expect my first speaker to be without major flaws . I am ok with bumps and warts just to go A-Z with the process. This speaker is not going to look like a slim-n-shiny commercial speaker. I do hope to outperform most commercial designs in some ways- just not max spls.

Project aims: Be domes, lots of bass, clean 2khz-5khz at many angles, small size, easy to breakdown (I move lots), minimal tools, neodymium magnets, keep it simple-no waveguides or complex cabinets, and around $3000usd with tools. Now these were my initial aims. I had to bend things around a little to get there. I also wanted to use drivers that were not 1st gen and that had 3rd party measurements. One last aim was to have the ability to mix and match parts in the future. I like the idea of making a coaxial next and having the ability to just swap things out. I used 4 wire SpeakON for EZ swaps.

I would not have attempted this at all if not for the help from users on this site and on diyaudio. Thanks to you all! I hope I can get more advice/guidance to wrap it all up.

Also, a big thanks to the creator of VirtuixCAD. I was able to learn lots by simulating different drivers, baffles, and XO’s using 3rd party measurements. He also answered my questions via email. Thanks, Kimmo.

And a huge thanks to a diy loudspeaker builder I found in town- hifijim on diyaudio. You are the best! Thanks again for all of the help (and the future help measuring).

Project features:

• Less than ½ the wavelength of the XO c-to-c distance for the tweeter and mid
• ¼ the wavelength of the XO c-to-c distance for the mid and woofer
• 44mm edge radius - https://fypon.com/products/mld605-12?variant=30373559697501
• Uses Denovo boxes – the box for the l26roy is good to go! The tweeter /mid box needs a custom baffle.
• 4mm space between the mid and the tweeter – Lasers make is so I don’t have to become a wood worker.
• Minimal tools required. Just clamps, a drill, sandpaper, miter saw, allen wrench, and a soldering iron. (I might be missing some things but the point is an apt/condo dweller build) The baffle for the tweeter/mid is laser cut using an online service. The sub does not require anything custom.
• Dual sealed subs

Right now I am waiting for a couple of new parts and then I should be able to wrap up the baffle. Next up: lots and lots of measurements. I have access to an indoor pool with high ceilings and hope to get cleaner measurements once the TM box is wrapped up. This won’t help with the bass though. I’ll get into the weeds of each part of the speaker as I get it done.

The last mile is the hardest and I hope to get this wrapped up soon.

Photos:

• The layers of the baffle. The top baffle layer is hardboard and walnut. Based on https://www.witpress.com/elibrary/wit-transactions-on-the-built-environment/59/18 I decided to toss some in since bamboo should help for mids. The bamboo material that is made up from layers of bamboo veneer. The small rings are for adjust of the height as needed. They are .5mm tall and also bamboo veneer.
• Bamboo graph from paper
• Dry stacked baffle with unfinished walnut veneer.
• VCAD sim that is made from 3rd party measurements- NOT REAL. This is just my guide made from traced measurements run through the baffle sim.
• Early temporary baffle made from pink foam sheets (an idea from hifijim). Jim made a whole speaker out of the foam and it sounded awesome. A person could cut a baffle with just a razor blade. I wanted to test of the speaker was loud enough before committing to the laser cut baffle.
• Temp baffle with 44mm edge radius. The TM box is about 9” tall and 8” wide.
• “”
• L26roy in its temporary position. I don't have it sealed up yet because I still want to compare measurements with diff. amounts of stuffing.
• Distortion at 1 meter and around 83db.
• My latest measurement at 24”. I've been trying to clean up the XO at 1700hz and 320hz. I did a partial sweep to cover this.
• XO timing measurements.
• rt60 decay
• A very rough and close polar.
• Unsmoothed gated 24" measurement.

 

[headshake]

inching along...

I just got the last stand done.

I needed something to hold the 22lb l26roy (i need to weigh to confirm) and the PE sub box. I think they are around 60lb combined. The "Prefinished Decorative Square Edge Shelf "from the local hardware is $5.32usd ea. Add some screws and metal corner brackets for strength and call it a day. The pair of stands cost just under $60USD with hardware. I left the stands separate so I can fold them up when I move.

https://www.menards.com/main/storag...edge-shelf/2114198/p-1444428244369-c-5702.htm

For me, clamps were cheapest from harbor freight tools.

Photos:

• The glue dries clear and leaves a nice seam. I did a dry fit first and marked the holes for the metal corner clamps. Predrill!
• Corner clamps and 2" clamps.
• The PE sub box on the stand. The sub has 3 coats of "Tried & True Original Wood Finish". I like the stuff because there are no VOC's. The stuff is wax and oil. I like the color and it should offer some water protection. Really it was a lazy way to get it done. More about the sub later.
• A dry mockup of what I hope to hear in stereo very soon. It will be even nicer not to see tape.

 

[headshake]

I was curious about how much my room/baffle was messing with measurements so I did a little test moving the mic closer and closer from 1 meter.

I am not gonna focus on things below 300hz until the speakers are in a better spot in the room but did a little test eq. I will do MMM in the future.

The "Mileseey X5 Classic " laser distance tool on ebay for $21USD is how I measured from the mic to the tweeter.

The laser marker from harborfreight is used to shoot down the mic and across the measuring distance to line the mic with the tweeter. It is nice having a laser line instead of just eyeballing it.

 

[LearningToSmile]

Cool project. Out of curiosity, is the mid/tweeter box a smaller rectangular box with the moulding on top just to form the baffle, or is the the moulding actually acting as the side wall of the speaker enclosure?

 

[headshake]

Cool project. Out of curiosity, is the mid/tweeter box a smaller rectangular box with the moulding on top just to form the baffle, or is the the moulding actually acting as the side wall of the speaker enclosure?

Hi. Thanks!

The moulding is just on the outside.

 

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pics

box: I got the main amp box all ready. It uses a laser cut mdf + walnut veneer for the top. The hex screws are off ebay. That seemed to be the easiest place to get 10mm-15mm screws. I use them on the speakers too. Only the one side has a remote cable cut-out. The top is glued to a "Bud AC-411" box using "loctite power grab". I had to clamp it down on top of a 5 gallon bucket because most of my clamps are 2 feet.

baffle: The laser cutter goofed on the top baffle layer by 1.2mm and sent me a replacement part to make up for it. I put a quick layer of oil/wax on it to see what it looks like. The walnut veneer + hardboard looks nice to me! I was not expecting to have matched pairs. This might be a perk of making something so small.

Friday I should have the last parts I need to wrap up the baffle. Fingers crossed.

 

[headshake]

A storm stopped my box from showing up Friday. Next week I will finally be able to complete the baffle. The universe wants me to listen in mono a bit more.

Speaking of listening...

My jbl 580's have glass in the plastic horn cover to dampen sound. This fact always has me thinking about dampening on the baffle. I've seen lots of posts on the benefit of wool on the baffle and thought I would give it a try. Worst case- it is a dead-end and I wasted $70USD. From my measurements of a few different shapes, it looks like it could work.

The first round of felt tests used a bad eq, bad xo timing, and taped felt. The next round will be on a flush baffle and glued. When I get my box next week I'll have 6 parts that evolved out of the first run of shapes. My hope is to only dampen things where the measurements say it will improve things.

Pics

• The "full felt" shape. It is cut a little long to blend into the sub. This is my first attempt at gluing it. I used rubber cement to hold down the felt. A sheet of melamine is in the background.
• A bunch of spl's from diff felt shapes. There are a few repeats to confirm things. I did a few sessions like this.

 

[bigjacko]

A storm stopped my box from showing up Friday. Next week I will finally be able to complete the baffle. The universe wants me to listen in mono a bit more.

Speaking of listening...

My jbl 580's have glass in the plastic horn cover to dampen sound. This fact always has me thinking about dampening on the baffle. I've seen lots of posts on the benefit of wool on the baffle and thought I would give it a try. Worst case- it is a dead-end and I wasted $70USD. From my measurements of a few different shapes, it looks like it could work.

The first round of felt tests used a bad eq, bad xo timing, and taped felt. The next round will be on a flush baffle and glued. When I get my box next week I'll have 6 parts that evolved out of the first run of shapes. My hope is to only dampen things where the measurements say it will improve things.

Pics

• The "full felt" shape. It is cut a little long to blend into the sub. This is my first attempt at gluing it. I used rubber cement to hold down the felt. A sheet of melamine is in the background.
• A bunch of spl's from diff felt shapes. There are a few repeats to confirm things. I did a few sessions like this.

Very interesting to test the effect of felt in front of speaker, I think it should reduce some mid frequency going 180 degree back and bounce off front baffle, but not sure how much the effect is and whether it is worth it. How did you take the measurement? Did you move the microphone or surrounding furniture? The deviations are within two dB, I think maybe measure with MMM is better. BTW what is the glass in the pastic horn cover on your JBL 580? How does it damp sound?

 

[headshake]

BTW what is the glass in the pastic horn cover on your JBL 580?

https://www.jbl.com/loudspeakers/STUDIO+580.html

The Studio 580 features a 1-inch (25-millimeter) tweeter mounted on a glass-filled Bi-Radial® horn – the technology used in JBL concert sound systems – to deliver concise, sustained high frequencies.

As for how it dampens, I really don't know. It could be something that benefits a horn and not a flat baffle. Phonons?

How did you take the measurement? Did you move the microphone or surrounding furniture? The deviations are within two dB, I think maybe measure with MMM is better.

Mic is on axis with the tweeter 1m away. The speaker did get bumped a little between moving the felt pieces on/off the baffle- this is why there are many repeat measurements. I've also tested out 0 and 90 degrees to see what is happening with the felt. You are right about the off-axis loss of power. I will be sure to try MMM.

but not sure how much the effect is and whether it is worth it.

Me neither. I do have one foot out the "this is a waste of time" door. I really did it just because I could. I kinda went laser-cutting crazy. I also made wool felt plugs for the woofer mounting holes if I don't use a sheet to cover the baffle. There will be felt somewhere when this is over!

 

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Some pics from today's box....

Pics:

• I grew up throwing stickers on my pc to show what was inside. It seemed right to make a little badge for the speaker. This is a blonde bamboo wood veneer sticker with some laser-etched branding. Eton was easy since they have a vector on their site. Seas have the tiniest raster graphics on their site and it needed the most effort (seas, how bout some svg's?).
• This is how the laser items show up- with paper on both sides.
• Round 2 shapes. Fingers crossed that one of them works out.

Ok, measuring time...

 

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Did some felt vs no felt measurements- round 2. Well, I thought I had an understanding and now I am back to start.

I noticed that some of the dips and peaks that happen when felt is added to a baffle were at the same spots as the filters I was using. So I then decided to start clean with a felt sheet on the baffle and make it flat.

The first image shows the different felt shapes on a baffle with an eq made to be flat w/o felt. The rest of the images is a comparison of flat with felt vs flat w/o.

I did a MMM and compared it to my 2ft gated and they were similar so I stuck with single measurements for now. From 1khz and up is still my focus until the speaker is all stacked up. One thing the MMM did show is how much of the noise floor is reduced off of a felt baffle.

So my felt side project has more questions than answers. Next up is a looks at the off-axis and I will try to stack up the felt and see what going too far looks like. The vs measurements below used one of my smaller sheets of felt and only a single 3mm layer.

I do also plan on a side-by-side mono shootout once things are done and felt will probably be a part of that.

 

[bigjacko]

Nice! From first image I can see that 4 to 5k increased and 7 to 9k decreased, interesting finding but not sure why it is. The RT60 and waterfall had some offset difference, not sure if it is just time offset or felt did the work. Do you have image for difference setup in your first image? That would be easier to see the result.

One thing the MMM did show is how much of the noise floor is reduced off of a felt baffle.

What did you mean by this?

 

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but not sure why it is.

Me neither. Being a newb I am just shooting tiny spitballs of what I know in the dark. My guess is I am changing the shape of the baffle in 3d and this is causing crazy things.

What did you mean by this?

The high frequencies had a different curve down with a MMM with and w/o felt. I hoped a little experiment would show you.

I used REW's RTA to measure my room in a few spots. Blue is 2 ft from the baffle.. a room measurement. Orange is the picture- the mic in the middle of the baffle with felt. Green is w/o the felt in the same spot. I really should have moved it 3mm closer once I moved the felt out to be fair.

So it looks like when it comes to the room bouncing off the baffle, I might want to keep it just around the tweeter. And if I was a bat, felt would sound quieter than the room.

 

[bigjacko]

For close up with felt or without felt, the results showed very little change, probably even smaller than the tolerance of the mic. So MMM measurement compare to normal way shows a bit less noise bouncing off front baffle, was this what you mean?

 

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For close up with felt or without felt, the results showed very little change, probably even smaller than the tolerance of the mic. So MMM measurement compare to normal way shows a bit less noise bouncing off front baffle, was this what you mean?

It is still early morning so I did a 500-2000hz Pink Periodic speaker cal. with a MMM at 2 or so feet away. The eq was made to be flat with the felt. The bump at 7k is me hitting my chair. If I smooth things the felt is almost -3db at 2.6khz. This is what I meant by saying "One thing the MMM did show is how much of the noise floor is reduced off of a felt baffle.".

I will do more measurements to confirm. It does also look like the felt drops off sooner/sharper.

 

[bigjacko]

Wow, did not expect the felt can reduce noise floor that much, it is worth to dig more from here.

 

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I did a couple more tests.

One, a mmm with 3 layers with the same setup as above. The eq is flat for the blue felt setup.

Two, a 4 layer felt baffle (really it is only 4 layers in the middle) with and without. The rt60 decay at 2ft does not show much benefit. My measurements before were closer than 2ft after using a laser distance meter to get things down. The spl's are off because I did this in the early am and did not calibreate.

Maybe this does not matter at a meter? I will do 3 measurements and average for the next run. I am now thinking of a 9mm felt baffle and ditching the walnut veneer + hardboard if more tests show this is ideal for nearfield.

 

[bigjacko]

For the first two pictures, with felt 4k to 5k and 12k to 15k Hz actually increased. The last picture under 500 Hz always goes up and down, is it because not enough resolution? The high frequency for blue and orange looks similar, both are better than no felt but only 1dB or less. Is RT60 measuring the room? If it is measuring the room then no wonder the felt had no effect when measuring at 2ft.

 

[headshake]

For the first two pictures, with felt 4k to 5k and 12k to 15k Hz actually increased. The last picture under 500 Hz always goes up and down, is it because not enough resolution? The high frequency for blue and orange looks similar, both are better than no felt but only 1dB or less. Is RT60 measuring the room? If it is measuring the room then no wonder the felt had no effect when measuring at 2ft.

I think it is how I am doing the MMM. To test things out I did a wide and narrow MMM with and w/o a single felt sheet. The "wide" measurement would go wider than the baffle. Narrow would stay within the baffle. I did it twice and averaged them. The mic was 1ft to 1.5 ft forward and backward. Each MMM RTA had a min of 40 averages. The EQ is made to keep the w/ felt flat. I did a speaker cal tone because it is late.

It looks like when I go off-axis from the felt all benefit disappears.

"no wonder the felt had no effect when measuring at 2ft" I had that there for reference.

 

[bigjacko]

Seems like wider than baffle the noise floor is higher with felt.