First diy project: Bose buster

[augerpro]

EDIT 5/12/2007 For final XO and enclosure build go here:

https://htguide.com/forum/showpost.php?p=336408&postcount=65

Hi everyone! I've started my first project finally. It's a 5.1 sub/sat system using HiVi M series drivers and the Dayton ND20. L&R are MTM (M3N), center is WMTW (M3N and M4N), and an M8N for the sub. I've built the test enclosure for the mains so far. The finish will be a maple veneer with piano black caps on the top and bottom like the speaker in the picture. Here are some pics.

[joecarrow]

Looks great! Good choices on the drivers; with a sufficient highpass and good room placement for the sub, it could be miles better than Bose (and similar names) with a very similar form factor. I look forward to seeing more.

Edit- I had a thought- did you have any trouble with the tweeter centered on the baffle like that? I was playing around with The Edge a little while ago, and placing it off-center really seemed to help smooth the response.

[augerpro]

Looks great! Good choices on the drivers; with a sufficient highpass and good room placement for the sub, it could be miles better than Bose (and similar names) with a very similar form factor. I look forward to seeing more.

Edit- I had a thought- did you have any trouble with the tweeter centered on the baffle like that? I was playing around with The Edge a little while ago, and placing it off-center really seemed to help smooth the response.

Thanks for the comments JoeC. Ya know I was in such hurry to get a test enclosure done so i could start on the XO that I spaced simulating diffraction before I drilled the hole. Now I'll justt use it to verify the woofer performance. Good catch

[ThomasW]

Those are really cute. It's funny to see them on the bigger speaker. Only then does one understand how tiny they really are. Good job.... :T

[---k---]

Yeah, what Thomas said. Those are tiny! Keep us updated.

[JonMarsh]

Very cute- amazing how small they are, the proportions look like a bigger speaker.

Curious to see how this turns out.

[joecarrow]

Thanks for the comments JoeC. Ya know I was in such hurry to get a test enclosure done so i could start on the XO that I spaced simulating diffraction before I drilled the hole. Now I'll justt use it to verify the woofer performance. Good catch

I didn't play with such narrow baffles... might as well sim this one to see if you don't have to throw it out, you know?

I've got to think about this kind of project. I love my Modula MT's but... I can't fit a larger TV on the stand unless I make the speakers smaller. WAF won't allow anything else

[augerpro]

Thanks for the kind words everyone. This project is for my mom now that she has "one of those fancy bigscreens" :lol: It seems when you're not trying to make the "ultimate" speaker you can have alot of fun. That's what this system is for me, fun. And tiny. I can't wait to hear how those tiny speakers sound.

I'm hoping to have a crossover and final enclosures done this coming weekend. JoeC I did a sim and the main difference to the offset was a smaller dip at @4k. Since the baffles are so narrow I really couldn't move the tweet all that much. Regardless I decided to make some small changes to the baffle so a new box is in order anyway.

[JonW]

They're very cute. It's kind of like "baby's first MTM."

[garto]

I may have missed it, but what are the exact dimensions as of yet.

[---k---]

This project is for my mom now that she has "one of those fancy bigscreens" :lol: It seems when you're not trying to make the "ultimate" speaker you can have alot of fun. .

That is what I was thinking. These are the type of speaker I would love to build for my dad or someone else that can't tell the difference between a HTIB and my system. And it would let me build something. A lot of projects are too expensive to do, just to do something.

What is the build price of these?

[augerpro]

garto- 4.25"w x 9"h x 8"d I started with 3 liters for testing and raised that to 3.9l for the finished box to make room for the XO. Which I hope fits in there, it's a tiny inside the box.

---k--- About $300 for parts for the whole 5.1 I think. With boxes and veneer maybe $400-450 or so.

[garto]

Yea wow these sound attractive for my dorm room where bigger speakers really don't fit. I can throw a sub under the bed but I can't exactly put regular bookshelf speakers on my desk (too wide). If you don't mind, pm with your plans. I'm very interested in these.

[PoorboyMike]

I really like your idea as I've been thinking about something similar for my parents. They just purchased a 50" Sony 3LCD but don't have anything as far as sound goes other than the speakers on the TV. I built a couple of "office speakers" with the B3N alone and was quite pleased with the sound considering the very small cash outlay. I'm really interested in hearing how these turn out for you.

[augerpro]

What do you guys think of the graph I attached. Both FRs are for the M8N in identical enclosures. The FR with lower extension is modeled from imported info from SPLTrace and the manufacturers graphs. The other FR is using my actual measurements of the woofer using SE. Why the big difference in response? I ran the M8N at high volume for 24 hours playing a bass heavy song. Maybe it didn't get broke in enough? The VAS measured 43L where the manufacturers specs are 53L I think. BTW I did try using sine waves for breakin at first, but I don't think my amp likes it. It pops randomly during the track and after a while it makes some really bad noise.

Brandon

[jdybnis]

How does it model using the manufacturer's t/s params?

[augerpro]

How does it model using the manufacturer's t/s params?

The FR with better extension is from HiVi's numbers. I copied the TS into SE and SPLTraced the response. So either my woofer wasn't broke in, HiVi is overly optimistic, or my FR measurement was wrong. I'm pretty sure my measurement was ok, just a standard nearfield measurement.

[dlneubec]

I'm not that experienced, but that looks like an awfully flat nearfield FR. Can you explain what settings you used in SE for that measurement? What gated window width or time did you use? The Hi-Vi one looks more like a sub output. Somthing looks amiss to me.

[augerpro]

I'm not that experienced, but that looks like an awfully flat nearfield FR. Can you explain what settings you used in SE for that measurement? What gated window width or time did you use? The Hi-Vi one looks more like a sub output. Somthing looks amiss to me.

This particular graph I did not include Le so they seem very smooth above the rolloff.

[augerpro]

I've made more progress on my project after spending the weekend seting up better dust control and building a new workbench. I have some camphor and bubinga veneer that looks cool as hell. But I've decided to go with some maple that should be in soon. Pianolac will be used a finish.



Well here is my first official XO EVER!! Woohoo! Please any helpful pointers would be nice. I would like to take the tweeter to 2nd or 3rd order, 4th costs more and takes up more space. Both of which fall outside the goals of this project. Jon M a while back I asked about calculating Q of the XO and you reminded me it was inherent to the filter class, Butterworth, LR, Bessel, etc. Well I remembered what made me ask that in the first place- no one ever uses the textbook Butterworth or LR, so now how do you calculate the Q? The Speaker building 201 book had an equation, but the syntax was wrong I believe so I couldn't use it. Anyhoo here are the results of my toil. In the FR pic the top blue line is the summed response of speaker.

Image not available

[augerpro]

Also reverse polarity on the tweeter shows a 15 dB null. I had a better one at one point with a 2nd order topo but couldn't get the 4th order rolloff I was looking for.

And Joecarrow- I forget to offset the tweeter...again. The diffraction simulations weren't that different though, i think the small size of the baffle limits how much that changes i think.

[joecarrow]

I wouldn't worry about it too much! It's a very small sin, compared to what some small cubes try to get away with.

[augerpro]

JoeC I'm beginning to regret not offsetting that tweeter. That 4K hump is in a bad spot and it's making good phase integration near impossible. Although judging from the sims I think i would be stuck with that hump even with the small offset I would be limited to doing. I did manage to use 2nd order topos on both HP and LP which accomplished a a little better then 3rd order rolloff. The rolloffs are slightly assymetrical so I could better phase integration. But I never did get great null, only about 9 dB deep. I tried moving the XO point around but it was either good null and a huge hump at 4k or a small null and an acceptable hump. I used actual values from PE for the XO. Unless anyone sees something amiss with the XO I'm inclined to stop here and buy the parts and build my first speaker!


EDIT: pictures of XO accidentally deleted ops:

[augerpro]

Does anyone have any opinions on the Jantzen/Solen/Dayton caps? They are all similar prices at PE.

[timber_mg]

I'd say rather even move the x-o up a little or live with the poorer phase integration because a 3-4dB relative bump at 4kHz will sound a little sibilant and when the woofer is played a little louder and compresses as it will invariably do its response will shelve down a little more than the tweet and then it's likely to sound a little strained. If you'd look at power response it'd be wise to put in a bit of a "bbc-esque" dip there anyways as you'd be looking at more than just the on-axis peak.

I have also been playing with a little project using two cheap 4" drivers and a shielded TDFC and have found that a bit of a shelf in that frequency range helps maintain respectable sound when you do start asking more of them. I do however cross @ 1k4 active most of the time where I can afford some more leniency as this is more of a joke project (Behringer digital crossover).

[timber_mg]

It is lightly documented here http://www.avforums.co.za/index.php/...7.html#msg3317
very rough quick and dirty proto (and the cut-out was originally for another tweeter though I've settled on a 2" TB on a small waveguide)

DRC for EQ and a helpful room mode at 55Hz makes for some astonishing results.

[augerpro]

Thanks timber for the comments. My mind was kind of going in the direction of what you had mentioned already. After getting some info on tweaking filter Q I made the shoulder of the HP a little shallower, resulting in a 2 dB difference between the dip at 3k and the peak at 4k. That's livable i think. I also dropped the entire 1k to 2k Hz area. I was afraid the speaker might sound shouty.

[69Stingray]

How does the impedence peak at 2.5 kHz effect sound quality? I think it is larger then I am use to seeing (or is it?).

[joecarrow]

I think it looks good, although crossover behavior is not my area of expertise. Giving it a little more of a critical eye, I wonder if the tweeter might be crossed over a tad low. It's only a 3/4", after all. Zaph's tests said it's best over 3.5khz. If you already knew that and made the choices you did, I say build it.

Regarding caps, any of the poly caps are miles better than what you generally see in cheap commercial speakers. The same goes for the air core inductors, compared to iron core. I used a combination of Dayton caps and GE surplus caps (from madisound) for my Modula MT, and it sounds great. Just keep in mind that you can build your non-standard caps by building up standard ones in parallel, thereby getting reduced prices for buying more.

[jonathanb3478]

Very nice project. I am very interested to see how it sounds. I might buy the parts to build a test unit (maybe even a pair) when I finally order my RS TMWW parts from PE.

One thing, though. What is your approach to BSC? I assume you are planning for on-wall placement. Is this correct?

And just one last... are you using 1/2", or 3/4" MDF for the enclosures?

[jonathanb3478]

garto- 4.25"w x 9"h x 8"d I started with 3 liters for testing and raised that to 3.9l for the finished box to make room for the XO.

I did the numbers (with 1/2" MDF construction), and those external dimensions still give 3 liters of internal volume.

If you actually want 3.9 liters internal, at least one of those external dimensions needs to be increased.

[augerpro]

I HATE WEBSENSE :M I write a whole reply and it gets blocked and lost. So this reply will be shorter.

69Stingray- I don't know what to think of that Z peak either.
joecarrow-Zaph did 3.6k with 2nd order acoustic rolloff. I'm doing 3.2k with better than 3rd order acoustic rolloff, almost 4th order. So should be ok.
jonathanb-Full BSC because these will be used on stands about 2 feet from the wall. They were originally intended for my Mom's entertainment center so I hadn't planned on full BSC. Now my parents want to get inwall speakers so they aren't visible. I'm using 1/2" MDF. I'll post the newest enclosure measuremnts, I did tweak them a bit. My goal was 3 liters AFTER the XO and driver displacement was accounted for.

I'm going to some offaxis measurements and see how they work with the XO. I should have done this first place. I fought with hump at 4k before I realized it was solely caused by the baffle and may not appear at say 15 degrees of axis. I'll know Monday night if this is the final XO after I do that comparison. Tuesday I'll order the parts to finish the L&R and the M8N subwoofer off. Th sub model reahced Xmax at 40 watts so I'm thinking this should be ok: http://www.partsexpress.com/pe/showd...number=300-784
Any other small but good plate amps out there?

Thanks everyone for the reply so far!

[augerpro]

Well I've done some offaxis measurements and the XO parts are ordered. I'm going to try two different caps for the tweeter. It seems with a 5uF the onaxis is relativley flat, but 15 degrees offaxis there is the big bump at around 4k. The 4uf cap puts a bit of dip in the onaxis but the offaxis is better. I think the 4uF cap is the way to go because it will give me some room for toe in adjustment for the best sound.
Here is the FR witht the 4uF cap. Blue is 15 degrees offaxis and purple is on axis:





EDIT 4/25/2007 Because I screwed up slightly when I measured the woofers I added a 1.5 Ohm resistor just before the tweeter . With this the actual measured FR on axis will look like the blue FR above.

[tyler]

I've made more progress on my project after spending the weekend seting up better dust control and building a new workbench. I have some camphor and bubinga veneer that looks cool as hell. The pictures are too red though, the veneer is brownish. But I've decided to go with some maple that should be in soon. Pianolac will be used a finish.

Nice build. Post some pics of the veneer when it is on.

[joecarrow]

My money's on the 4uF, but it looks awesome regardless of which way you go. I look forward to hearing how it fares with the subwoofer.

[Nathan P]

Those would be sweet as rears on a small room system.

[augerpro]

Finished the XO's. I used hot glue to attach everything to the board. I also hot glued wherever the the inductor's lead crossed the coil. I know they are plastic coated wires but I figured if they touch the vibration may wear away the coating and short. Boards are 3" x 7", I could have probably stuffed them on something smaller. I used Jantzen 18 gauge coils and Dayton caps. So do these look acceptable?





Enclosures are waiting for veneer:





The top and bottom caps will be piano black and the rest maple pomelle veneer. I'm doing test run with some camphor veneer on an old box tonight since this is my first time veneering. If all goes well I'll veneer the actual enclosures tomarrow. So I should a finished speaker this weekend! Waiting for some Pianolac to arrive for the caps. The baffle measures 4.25" x 9.5" without the caps. With caps the height is 10.5" The subwoofer box will have teh same general look as the MTM's.

[joecarrow]

Crossovers look great! Just double check that everything has a good solder joint- I hate when I put something together and forget to solder one, just leaving it twisted together.

Piano black is ambitious- I wish you luck with it! Once again, this looks like a cool little project.

[MuaDibb]

Hey Auger, nice work. I was in the process of attempting to make some computer speakers with the same drivers that you are using. I'm still really new and I was wondering if any of the work you have done will apply to what I am doing. These will be nearfield monitors placed close to the wall so I think BSC will not be needed. My configuration was going to be TMM and look like this(roughly).





Could it be as simple as moving the placement of the drivers or will it be necessary to design a new crossover. My thought was with the listening position the tweeter would be closer to ear level.

If anyone has thoughts or helpful comments they will be greatly apreciated.

[augerpro]

MuaDibb you would have to copy my front baffle for the XO to be usable. Are you able to take FR measurements of the drivers on your baffle? If you are we might be able to cook up an XO for you. I like the shape!

[MuaDibb]

Thanks for your reply. Thats pretty much what I expected. I can put them on a baffle and measure, I'll go ahead and order the speakers. Worst case scenario, I just copy your design if it doesn't work out and I still get new computer speakers. :T

As for cabinet construction, my intent was to house only the Hi-Vi's in an actual box, where the tweeter is located the baffle extends above the box, so the tweeter will be in free air. Will this present any problems?

Last question, do any of the diffraction programs simulate an odd shaped baffle so I could optimize the speaker placement before I cut the baffle?

Edit- I downloaded the Edge and have simulated the baffle but I'm not really sure about what I should be looking for as far as the graph.

Its not my intention to 'jack this post, should I start another thread?

[augerpro]

MuaDibb teh tweeter has a sealed back I think so it will be fine mounted on an open baffle. Were you able to model your baffle shape on the edge? Just place the drivers where they would be on the real baffle and remember to move the microphone dot on axis with the tweeter. Since you will be listening nearfield you may want to move the mic to represent the listening position too, just to get an idea of what has changed between that and the on axis tweeter postion. Once you graph the results try moving the drivers to the side or vertically a small amount and see how the FR changes. You want to find the position that is acceptably smooth to you. I will say though that your original baffle shape with that tweeter position will probably be as good as you will get. Just verify that it will not cause any large dips or peaks anywhere.

[augerpro]

1)I need some advice from the woodworking studs around here. I need a sprayer for teh Pianolac. I'm looking at what Lowe's and HD carry. At Lowes is a nice looking Kobalt HVLP sprayer model 577A for $90. I would post a link but it's not shown Lowes site. Then HD also has a couple HVLP for a bit cheaper. Anything I should look for in particular?

2)Also on the veneering front I was going to try Heatlock last night and teh bottle was setup solid. Apparently if it freezes it solidifies and it's junk. Joewoodworker is being very cool and sending me another bottle. In the mean time I wa going to try using the Titebond iron on method. I'm going to be placing the veneer on the sides and wrap it around the front where it will have a seam in the center of the baffle. In the Heatlock FAQ it says not to use if there is seam since the shrinkage will pull the edges away from each other at the seam. My question is is this a problem with the iron on Titebond method too?

3) What kind of primer should I be looking at? Anything that WILL NOT work with Pianlolac or similar?

[crackyflipside]

What's the budget per pair. (Drivers + X-Over)?

[PoorboyMike]

What's the budget per pair. (Drivers + X-Over)?

I'd like to know also.

And more importantly, how do they sound?