The Schlafmutzes Mini MT’s design and progress

[5th element]

Hot melt glue is definitely your friend when assembling crossovers. I just hard wired an xover into a tiny cabinet and had real difficulty arranging the various components such that they would all fit. It was the large inductors that I had issues with, the caps I were already NPEs! I am glad I didn't try and fit some poly caps in.

[JonW]

Been a little busy here so no progress to speak of. Hopefully I can start wiring things up in the coming days. And gluing things together.

It must feel good! They're looking great! I'm quite impressed with your crossover layout ingenuity. I'm terrible at figuring out where to put the pieces

Thanks, Kevin! I don’t know that I’d say the crossover layout is really an example of ingenuity. It’s more like being backed into a corner and not having many options for how to get out.

Hot melt glue is definitely your friend when assembling crossovers. I just hard wired an xover into a tiny cabinet and had real difficulty arranging the various components such that they would all fit. It was the large inductors that I had issues with, the caps I were already NPEs! I am glad I didn't try and fit some poly caps in.

Yeah, hot melt glue seems to be the way to go here. NPE caps in a small cabinet? Man, you’re taking the easy way out! :P

In order to make sure that things bond well and don’t fall off the board when mounted on the cabinet side, I covered one of the inductors with glue. You can see it in this reposted picture. It’s 0.9 mH, has a DCR of 0.67 Ohms, and is a filter/shunt, not in the main path. I am wondering if it might get a little warm and I should shave the glue off the top. But I am leaning toward keeping it as is, for the good bonding.

I never mentioned this point but probably should: All the resistors are floating in the air, for good heat dissipation. None are glued down to the board.

[JonW]

“Daddy will you play with me?”

Hey Fellas,

I’ve restarted work on this speaker project. It’s been far too long. But I’ve got a little kid around now and they take up a lot of time (and money). Who knew? Plus I’ve got a pretty demanding job. When my son says “Daddy will you play with me?” well, that’s what I’ve got to do. At least for now, while he still wants to spend time with me. Anyways, I got a little time to get the speakers going again. I’m hoping to get them complete over the next couple of weeks. But we’ll see if that really happens.

I’ve worked on getting things wired up. One photo is shown here. It’s quite the puzzle of wires and getting everything into these tiny cabinets. Last night, I got the first speaker (of four) actually playing music for the first time. What a smile I had on my face. It sounded amazing.

Still a lot to do in terms of wiring things up and testing to make sure everything is AOK. Plus many little things that go with it like cables, getting little rubber feet, making the external jumper cables to allow switching between the n room and on wall versions. I’ll post more details on how I accomplished various aspects of the build as I get things farther along. Eventually, I’ll also make a parts list (BOM) and provide any additional info needed if someone else dares start the build.

[technodanvan]

This is the best kind of thread necro.

[5th element]

Wow was it really back in 2014 that these were last worked on!

Excellent to see you finally making progress, I know what it's like having to put projects on hold.

[Alaric]

When my son says “Daddy will you play with me?” well, that’s what I’ve got to do. At least for now, while he still wants to spend time with me.

^This. Excellent sense of priority, there.

[JonW]

Thanks, guys. Yeah, it has been frustrating to watch these speakers, so close to being done, just sit there. But other priorities have come into life. The shortest person in the house does have me wrapped around his finger. Still, I'm going to get these things completed. Hopefully sooner rather than later. There is already enough info posted here for someone else to complete a built. But I'll provide more details and tips as the project progresses.

[JonW]

Last night I got some little things done like cutting up peg board, screwing in one woofer to complete the first speaker, and soldering several wires for jumper cables. I’m making the Deluxe speakers able to switch between the on wall and in room crossover versions by a simple jumper cable change. Details to follow on all of that. Nothing too specific worth a photo for now. Still a fair amount of work to do. But it’s more done and I’m happy.

[JonW]

It’s been, ummm, a while since working on these speakers. Life is still really busy. But I’ve restarted some of it. Trying to get back into things a bit. So a little progress has been made. No idea when I can have these things finished off, but I’ll try. Here is one photo of starting to wire things up. 😀

[technodanvan]

Great to see you again Jon, looking forward to this as I start my own endeavors with small two-ways!

[JonW]

Hi Danny!

Nice to see you and be back here a bit. It’s kind of quiet around these parts. And I could not even find this thread via Google. I wonder what has happened over the years. My interest in the hobby has persisted. But life has just been so busy. Maybe it’s similar with others. Anyways, good to see some enthusiasm. Best of luck with your mini projects! 😀

-Jon

[theSven]

Google was beating up on the forum with their bots scanning content. All the content is here though, and I have worked over the last couple of years to try and restore as many images as I could in the DIY forum. The forum is updated to the latest version and things are running nicely. Search has also been improved on the forum too. Glad to see you back!

[JonMarsh]

Life can be VERY busy at times- I don't make progress myself nearly as fast as I wish I could- since to see you back and having fun!

[JonW]

Oh, interesting. Sounds like a big mess that you have had to deal with. I appreciate everything that you are doing to keep things going!

Maybe Google and the other usual suspects are scanning so as to use our speaker designs to train AI to make it’s own speakers. If we see a post "The Skynet MT speaker" it's time to be suspicious.

[JonW]

I'll be (pleasantly) surprised if anyone else ever wants to build these speakers. The cabinets are a little complex, being angled and faceted. Fitting everything inside is challenging. And the deluxe version is not cheap. ($1,200/pair is a guess, although I'll work out details later.) So not exactly a beginner build. But just in case, I'll keep showing how I put these things together. A little more work is done.

This photo shows that how 1.25", 3 layer sonic barrier covers the entire back. Except for the part where the binding posts are. I've got 4 binding posts in there because I was trying different things with the crossover as the design progressed. But if I were to build another pair of these speakers from scratch there would only be the regular two binding posts.

[JonW]

Then I put in a little piece of peg board to cover the binding posts. Stuck there with hot melt glue. As you will soon see, it's really a tight fit for all components. So this little piece of peg board will help keep any wires, parts, binding posts, etc. from making any unwanted contacts.

[JonW]

And here are the crossover boards installed. They are hot melt glued in place. I separated the crossover into two parts, woofer and tweeter. The woofer board is on the top left. The tweeter board on the bottom right. Then I have another piece of peg board at an angle to separate the two boards just to help make sure that there are no unwanted electrical contacts.

[JonMarsh]

Sure is crowded in there! I'm kind of chicken, in case I make mistakes- use wide velcro strips for mounting the crossovers to cabinet panels.

[JonMarsh]

+ on the Mills resistors. Too bad PE is closing those out- they're one of my favorites for HF stuff.

[JonW]

When gluing in the crossover boards, and also putting in the Sonic Barrier, make sure to push things toward the back of the cabinet as much as possible. To have space for the woofer and wires.

Then we've got to get the woofer in there. It's all very tight. But it fits. Not with any space to spare., really But I can get it all in there and where everything needs to be.

[JonW]

Hi Jon!

Life continues to be really busy. But something fun like speaker building is a nice distraction from things.

Oh, I’m out of the loop a bit and didn’t realize that the Mills resisters are going away. They are nice. And small, so perfect for a project like this. Fortunately, resistors are an easy thing to find. Maybe some good alternatives are there for speakers?

Yes, hot glue instead of velcro. Things are so tight in here that I really don’t want any movement of parts. For fear of any unwanted electrical contacts happening. And the crossover boards are hanging on the sides. So I want them really secure. Oh, and the hot melt glue is thinner than the velcro. I’ll take the extra few mm’s of space in here. 😀

Your reply makes the photo look bigger, as though there is a lot more space in there to work than there really is. 😀

[JonW]

I just wrote out a bill of materials (BOM) and put that in post #3 on page 1 of this thread.

The BOM had links and was flagged as spam. Someone had to check and approve it. Whoever you are- thanks. 😀

[technodanvan]

You've really got everything crammed in there! I have a similar-sized project I've been sitting on because installing the crossovers will be a major pain...I might need to assemble them inside the cab. Small speakers are fun!

[Steve Manning]

You've really got everything crammed in there! I have a similar-sized project I've been sitting on because installing the crossovers will be a major pain...I might need to assemble them inside the cab. Small speakers are fun!

If you plan on stands for them, you could look at a design to put them inside the stands.

[JonW]

You've really got everything crammed in there! I have a similar-sized project I've been sitting on because installing the crossovers will be a major pain...I might need to assemble them inside the cab. Small speakers are fun!

Hi Danny,

Yes, I’ve seen your ongoing project. Looks like you are still settling on drivers? I do not have any experience with any of the options you mentioned, so no opinions. I like low distortion, so that’s usually my first criterion when picking drivers. Although it’s not always easy to find apples-to-apples distortion (and other) data when choosing amongst options.

Small seems simple, but turns out to be a significant constraint. At least for me. There are so many places where you can let the size creep up- use a regular flange sized tweeter, add a little volume for more bass, add cabinet size for the crossovers, let the cabinet dimensions get a little bigger to make the woodworking easier…

These speakers here were about as small as I could push it without any major audible compromises, 6.5” wide, 8.5” deep, 10.5” tall. You can certainly make something smaller, but your ears will have costs to pay. 😀

[JonW]

If you plan on stands for them, you could look at a design to put them inside the stands.

Good idea. If you are willing to do so, putting the crossovers outside of the cabinets could make like a lot easier!

[technodanvan]

Yes, I’ve seen your ongoing project. Looks like you are still settling on drivers? I do not have any experience with any of the options you mentioned, so no opinions. I like low distortion, so that’s usually my first criterion when picking drivers. Although it’s not always easy to find apples-to-apples distortion (and other) data when choosing amongst options.

Yet another project! This one is actually from around 10 years ago, back when the woofer was around 1/4th the price. The 'current' project will be a bit larger I suspect... Anyway, I had some help with the crossover, tested it and liked it, and now I just have to cram it in there sometime.

[JonW]

Wow, really great woodworking there! It's nice to see something different and creative. What did you use for wood and how did you put all of that together?

I definitely approve of the slanted and faceted baffle. A long time ago I made and measured a whole bunch of different test cabinets- straight versus rounded over versus faceted edges. Tweeter centered versus offset. Straight baffle versus angled back. In the end faceted, offset tweeter, and angled back baffle measured the best. Details are in my Spassvogel MT thread. I know that there are simulation programs for examining such differences. But it's also nice to see what happens in reality. Maybe some day I should do a specific and more clear writeup on those results.

Oh, and my son would approve of the Legos. They enhance all speakers. 😀

[technodanvan]

Thanks! I used some scraps of bamboo plywood and some small purpleheart sheets I had lying around. Dimensions of the speaker were constrained by the materials I had on hand in addition to the drivers themselves. They turned out pretty sharp, though I do wish I had a little more material to work with.

I have far too many LEGO sets around the house, most of them unbuilt...yet another hobby that I should scale back on!

In any case, I could see following your design process laid out here for another set of micro speakers. Perhaps not the same Seas drivers/crossovers though, but the process itself is quite helpful to see. I'm sure others will find value in it. I'm fairly certain this thread is one of the original inspirations for those little purpleheart/bamboo speakers, actually!

[JonW]

Bamboo ply and purpleheart are interesting. I like that they are unusual for speakers. 😀

It would be nice if this project helped give you, or anyone else out there, some ideas. The speaker building community is nice and supportive in that way. I like it.

Good luck with your project. Keeping things small and also keeping the audio quality top level is a fun challenge. Different people will go in different ways. I'll keep an eye on your project. Have fun with it!

[JonW]

Confession time...

I got all 4 speakers wired up and closed. And 3 of them worked beautifully. 😉 Sounded amazing. But one was really off. No sounds from the tweeter and things from the woofer were off somehow. I took an impedance sweep and it was pretty ugly.

Remember when I hot glued in the crossover boards? And JonMarsh said how brave that was? Really, implying that I'm an idiot. 😉 Well, Jon the Wise was correct. I am a moron. So a quick check on Google to see what you can do to remove hot glue. Without needing to heat the entire speaker. Turns out some isopropyl alcohol will dissolve it easily.




I opened the speaker back up. Found that the one tweeter lead had been ripped out and it didn't look to be easily fixable. Ordered another tweeter. Put it in. And now all is well. 😀

[JonW]

By the way, when ordering the replacement tweeter, it looks like this tweeter may be discontinued? So I will look around for an alternative. At the moment and only from a quick look, this one seems like it will be a drop in replacement:
https://www.madisoundspeakerstore.co...20-00-tweeter/
Similar flange size. Maybe 1 dB less output, but a similar frequency response. So it might warrant using 1 Ohm less in the tweeter padding resistors (R1), which is a super easy change. I will look into alternate tweeters later. For now, this tweeter and padding resistor value substitution may be AOK.

Now I have 4 speakers all sounding beautifully, as intended. 😀