The Bantams Micro Speaker System

[Danger dad]

Very nice work! I have been wanting to build some with PR's for a long time. I might have to build a set, Thanks for sharing!

[Unclemo]

Tom, thanks for this design!!! I made up a set of these for one of my girlsfriends daughters. I couldn't stand her listening to music with her cell phone any longer. These are a great little desktop speaker. She loves them!!! The other daughter got a pair of scott's heliums. They are both being enjoyed on a daily basis. For anyone who is worried about output, don't. I had these hooked up to my Peachtree 125 for a couple of weeks before Christmas and they can put out some sound for sure. I was amazed how great they sound. Here are a couple pictures, I was able to sneak the xover into the bottom of the without having to use the frame of the PR but it was a tight squeeze.

[mmu7]

Tom, thanks for this design!!! I made up a set of these for one of my girlsfriends daughters. I couldn't stand her listening to music with her cell phone any longer. These are a great little desktop speaker. She loves them!!! The other daughter got a pair of scott's heliums. They are both being enjoyed on a daily basis. For anyone who is worried about output, don't. I had these hooked up to my Peachtree 125 for a couple of weeks before Christmas and they can put out some sound for sure. I was amazed how great they sound. Here are a couple pictures, I was able to sneak the xover into the bottom of the without having to use the frame of the PR but it was a tight squeeze.

Very nice. How do they compare to the heliums, since you've built both?

[stephenmarklay]

Tom, thanks for this design!!! I made up a set of these for one of my girlsfriends daughters. I couldn't stand her listening to music with her cell phone any longer. These are a great little desktop speaker. She loves them!!! The other daughter got a pair of scott's heliums. They are both being enjoyed on a daily basis. For anyone who is worried about output, don't. I had these hooked up to my Peachtree 125 for a couple of weeks before Christmas and they can put out some sound for sure. I was amazed how great they sound. Here are a couple pictures, I was able to sneak the xover into the bottom of the without having to use the frame of the PR but it was a tight squeeze.

Those are very pretty. How did you finish the sides?

[Unclemo]

They are very similar to the heliums, at least to my ear. I never really did the a/b thing but they both sound great. If memory serves me I think I preferred these at more moderate listening levels. The tweeter on the heliums was a little more relaxed to my ears at the louder end of the spectrum. So for me if I was going to build some for desktop listening I would go with these. I honestly don't think you can go wrong with either though.
As for the finish on the sides, these are just mdf with some rattle can white with a few coat of deft spray lacquer from a can.

[tomzarbo]

Tom, thanks for this design!!! I made up a set of these for one of my girlsfriends daughters. I couldn't stand her listening to music with her cell phone any longer. These are a great little desktop speaker. She loves them!!! The other daughter got a pair of scott's heliums. They are both being enjoyed on a daily basis. For anyone who is worried about output, don't. I had these hooked up to my Peachtree 125 for a couple of weeks before Christmas and they can put out some sound for sure. I was amazed how great they sound. Here are a couple pictures, I was able to sneak the xover into the bottom of the without having to use the frame of the PR but it was a tight squeeze.

They came out great. A lot more exciting than my 'basic box' pair. Those things are really snazzy!
How hard did you find installing the tweeter? The first pair I made I used foam and I had to smoosh them in my twisting... real tough. The second time I worked on the Bantam MTM's I used electrical tape I think, much easier. Just wondering how hard it seemed for you.
I'm real glad that you like them. I think in Scott's Helium's they are crossed a little lower, but still pretty high, like around 6k or so... so the ND91 is still doing the majority of the heavy lifting as in my version.

TomZ

[Unclemo]

I cut the whole for the tweeter pretty tight and the used some black caulking on the back to make sure they were sealed up good. Could i get them back out? Not easily thats for sure. It definitely tiik some finessing. Thanks again, the girls love them.

[bsl100]

Tom, did you inquire as to whether PE would be bringing in this tweeter with the faceplate used in the B652-Air's? It's the same tweeter, just a different housing. Maybe it's a marketing thing and they don't want to offer it except in the B652's.
[ATTACH=CONFIG]n1305250[/ATTACH]

I have used these tweeters in a 2.1 boombox project which was based on a 4.2BT TPA3116d2 plate amp. The sattelite duties were done with a pair of these AMTs and the Dayton RS100-8 pair. Sub duties were done by the Tang Band W6-1139SMF. Superb sound all around and the off axis response from the AMTs was excellent.

You can buy these AMTs on the other 'express' website store. The one with the famous boxer's surname...

[bsl100]

Tom... Superb write up.

I have been a ND90-8 user for some time now and have paired them with the ND20FA-6 and AMTs in Sprite type boombox projects. Have also done a 2.1 boombox set up with the ND90-8 and ND20FA-6 doing satellite duties with the ND105-8 acting as the sub.

I recently completed a pair of separates using the ND90-8 with the ND25TA-4. They are in 4.5L boxes. I was worried about the peak at 17KHz with the tweeter. But, it was not an issue after adequate padding down with an L-pad.

I just happend to read about your project. Been wanting to use the ND91-4 in a small set up. Was considering the Heliums. The Bantams look like they can go a bit lower though. One difference will be that I plan to use the AMTs (similar to the ones on the B652 Air).

[kenny_k]

Congrats Tom on your Audioxpress article. https://simplecirc.com/view_issue/3576

[tomzarbo]

Thanks Kenny,

I tried to keep it simple and interject a little humor in it.
It pays to keep a sense of humor when you make as many mistakes as I do.

TomZ

[Trdat]

Tom,

I am a avid participant on this forum and after building the Bantam's I have been meaning to write a praise post. I just would like to say firstly thanks for your effort in the design my project came out very successful and turned out beyond what I thought a micro speaker can pump out.

The speaker is absolutely awesome, not just the SPL the general quality of the sound and the bass is phenomenal. I would like to add though that my wife does hear either some distortion in the high frequencies which obviously I can't hear, this could be the cheap tweeter(which isn't that cheap) or just general high frequencies that sound too silibant or the tweeter type. It could also be the lack of time alignment which isn't something we would expect at this price point or simplicity but something makes my wife think that something isn't right then again it could pertain to my specific build.

Putting that mild criticism aside, the speakers pump I love them. There is something about the transients i adore, can it be the small woofer? I know passive radiators don't match the transients of closed box and even a ported design but perhaps it is the tiny woofer.

Now and again I got to pull out the Bantam's hook it up to a descent DAC and power amp and listen to them. And sometimes it gives more pleasure than my main DIY set up which is worth close to 10k. So thanks the design I am sure the DIY community appreciates it.

[tomzarbo]

Tom,

I am a avid participant on this forum and after building the Bantam's I have been meaning to write a praise post. I just would like to say firstly thanks for your effort in the design my project came out very successful and turned out beyond what I thought a micro speaker can pump out.

The speaker is absolutely awesome, not just the SPL the general quality of the sound and the bass is phenomenal. I would like to add though that my wife does hear either some distortion in the high frequencies which obviously I can't hear, this could be the cheap tweeter(which isn't that cheap) or just general high frequencies that sound too silibant or the tweeter type. It could also be the lack of time alignment which isn't something we would expect at this price point or simplicity but something makes my wife think that something isn't right then again it could pertain to my specific build.

Putting that mild criticism aside, the speakers pump I love them. There is something about the transients i adore, can it be the small woofer? I know passive radiators don't match the transients of closed box and even a ported design but perhaps it is the tiny woofer.

Now and again I got to pull out the Bantam's hook it up to a descent DAC and power amp and listen to them. And sometimes it gives more pleasure than my main DIY set up which is worth close to 10k. So thanks the design I am sure the DIY community appreciates it.

Thanks for the kind words, I'm glad you guys are enjoying them. They are our main speaker system combined with my "Tenacious Bass-8" subwoofer system and we don't feel like we're missing anything sound-wise. I'd love to take the credit for them turning out to be such a great-sounding design, but I think I may have gotten 'lucky' a bit with the combo.

As to the high frequency distortion your wife is hearing, I have two theories...

When I originally was testing different methods to mount the tweeters, I ended up testing slightly different "depths" with each mounting method. When I took measurements with Omnimic, I noticed that variations in depth caused somewhat different high-frequency responses. The mounting depth that gave the smoothest response -- and the one I ended up using -- was to mount the tweeter so that the tweeter body protruded just to where the barrel began to curve towards the front and no more. In other words, the roundover on the tweeter face should be fully exposed, or proud of the baffle, but no further -- the tweeter should not be flush to the baffle.


I suspect that may be what you are hearing... a response signature that has a few more 'jaggies' to it than if the tweeter is mounted exactly as pictured above. I didn't save the response graphs of those less-than-optimum mounting depths -- and they weren't awful by any means -- but they were not as flat as the above mounting and 'may' be what your wife is hearing. That's the only bad thing about using these tweeters -- the mounting can be a little tricky.

One more possible cause... did you seal off the tweeter back where the wire exits the housing with caulking or sealant? I suspect the tweeter is not 'air-sealed' as it wouldn't need to be since it is intended to be used as an automotive tweeter. That 'could' cause some weird flexing of the tweeter membrane due to pressure changes inside the cabinet which may be heard as 'distortion' of some sort.

Without seeing your speaker I can't be sure, but I haven't heard anything I would consider 'distortion' from the AMT tweeters, and it seems that the response directly from the driver itself is unlikely to be the problem. They are crossed over pretty high at around 6,500 to 7,000 Hz, and they use a third-order crossover, so they are well within their safe and 'comfortable' limits.

I've built half a dozen of these speakers and have not heard anything I would consider 'off' on the high end, even at loud volumes, so I suspect one of these issues may be the cause.

Hope this helps, take care,
TomZ

[Trdat]

Thanks for the kind words, I'm glad you guys are enjoying them. They are our main speaker system combined with my "Tenacious Bass-8" subwoofer system and we don't feel like we're missing anything sound-wise. I'd love to take the credit for them turning out to be such a great-sounding design, but I think I may have gotten 'lucky' a bit with the combo. :

I didn't get a notification that you had replied, thanks for your response. The round over is exposed so not sure what is going on with what my wife is hearing. It could also be the AMT itself with it unique tweeter sound signature all my other tweeters are soft dome with one being hard dome but she definitively hears something. Still loves it just being a critic due to everything around her being speakers and audiophilery....

Also, If I am not mistaken, apologise if it was my mistake but the cutout you gave for the AMT was slightly larger. The hole could of been a few mm smaller making the fit for the tweeter more firm, I used your method of using double sided tape to fit it in and it worked good and did seal it tight. But I am wondering why we couldn't cut the exact hole for the AMT? Is the AMT a perfect circle?

I did add sealant behind the tweeters, I am a fanatic when it comes to sealing enclosures so leakage would be minimum. But reading your post a second time do you mean sealing the tweeter off around the cutout or behind the wiring? I don't understand why the wiring would need sealing? Also can you exactly confirm where I need to seal cause I am bit confused?

[Wolf]

Tom was referring to the wiring into the tweeter needing sealed, not the perimeter of the mount. A lot of times automotive products are not under the same pressure stresses as home audio drivers because they are not installed inside the same cabinet. For example- these would likely sit atop the dash, or be placed into an A-Pillar. The wiring from rear to membrane may very well be open, allowing an air-leak from the woofer pressure to intrude to the membrane of the AMT and add some unwanted flexure to its operation.

Later,
Wolf