Hobbyist Bluetooth Boombox Build FINISHED. Looking for specific feedback

[Hi-Fi Luggage]

Hi all, new to this forum.

Finished this boombox last week. Most components available at PE. The main feedback I was looking for is if someone with speaker enclosure building experience could take these measurements, and tell me if this enclosure is at all close to the recommended specs. I spent hours trying to figure this out on my own using speaker box calculators but could not come to any conclusions. My hunch is, this box is a too small for 4 of these drivers, however I have been very pleased during the initial listening sessions. Much more low-end extension than expected.

Enclosure measurements (W x L x H): 7" x 7" x 24"

(4) 3" Aurasound NS3-193

Wood thickness: 1/2" + roughly 1/8” sound deadening material: 5/8"

Port tube diameter: 2”

Port tube length: 4”

SURE Amplifier: 2 x 15 RMS

SURE Bluetooth board: 4.0 aptX +EDR

Battery: 4.5 mAh NIMH.

Black coating: Acry-Tech DuraTex

This build has a main on/off switch, separate on/off for bluetooth, AUX input, and a battery voltage meter on a momentary switch. The battery is mounted to an access panel via 3M industrial tape. All electronic boards are removable with appropriate cable lengths. Poly-fill added.

I was also looking for general feedback on the design, initial impressions, or any tips welcomed. I will also answer any questions. I don't have a lot of experiencing with wood working, no formal training, all of these builds just kind of came together with a table saw, jig saw, and whole saw bits haha. This is about the 5th wood boombox I’ve built. The first 3 were not battery powered. The third had a very small enclosure and sounded terrible and I never listened to it. I ended up taking it apart and using all of the components to build this current one with a much larger, ported enclosure. I also have a company called Hi-Fi Luggage and we make vintage suitcase bluetooth boomboxes.


Current build:

 

[TheWarrior]

Hi all, new to this forum.

Finished this boombox last week. Most components available at PE. The main feedback I was looking for is if someone with speaker enclosure building experience could take these measurements, and tell me if this enclosure is at all close to the recommended specs. I spent hours trying to figure this out on my own using speaker box calculators but could not come to any conclusions. My hunch is, this box is a too small for 4 of these drivers, however I have been very pleased during the initial listening sessions. Much more low-end extension than expected.

Enclosure measurements (W x L x H): 7" x 7" x 24"

(4) 3" Aurasound NS3-193

Wood thickness: 1/2" + roughly 1/8” sound deadening material: 5/8"

Port tube diameter: 2”

Port tube length: 4”

SURE Amplifier: 2 x 15 RMS

SURE Bluetooth board: 4.0 aptX +EDR

Battery: 4.5 mAh NIMH.

Black coating: Acry-Tech DuraTex

This build has a main on/off switch, separate on/off for bluetooth, AUX input, and a battery voltage meter on a momentary switch. The battery is mounted to an access panel via 3M industrial tape. All electronic boards are removable with appropriate cable lengths. Poly-fill added.

I was also looking for general feedback on the design, initial impressions, or any tips welcomed. I will also answer any questions. I don't have a lot of experiencing with wood working, no formal training, all of these builds just kind of came together with a table saw, jig saw, and whole saw bits haha. This is about the 5th wood boombox I’ve built. The first 3 were not battery powered. The third had a very small enclosure and sounded terrible and I never listened to it. I ended up taking it apart and using all of the components to build this current one with a much larger, ported enclosure. I also have a company called Hi-Fi Luggage and we make vintage suitcase bluetooth boomboxes.


Current build:

Looks neat! How do YOU like the sound?

Cause that's really all that matters. Speaker design is an incredibly deep rabbit hole. And for this type of application, there's a lot of inherent compromises. So as long as you are happy with what you've built, that is all that matters!

 

[Hi-Fi Luggage]

Looks neat! How do YOU like the sound?

Cause that's really all that matters. Speaker design is an incredibly deep rabbit hole. And for this type of application, there's a lot of inherent compromises. So as long as you are happy with what you've built, that is all that matters!

Well I am pleased with how it sounds, however that's not really what my original post was about. Because I am new to speaking enclosure design, I'm trying to understand if this design is, at all, close to the recommend specs, and also what this enclosure is tuned to.

 

[ski2xblack]

Maybe try an aperiodic port for a taste of non-resonant bass. Aperiodic loading is very forgiving of enclosure volumes and driver t/s specs, which will come in handy given you've already built the box and installed the drivers. You can gauge the proper amount of stuffing for the hole by looking at the impedance (do you have a Daydon woofer tester by chance?); when you eliminate or severely reduce the lowest impedance peak you're in the ballpark. You'll end up with a slightly higher f3 but gentler roll-off, and non-bonky bass.

 

[TheWarrior]

Well I am pleased with how it sounds, however that's not really what my original post was about. Because I am new to speaking enclosure design, I'm trying to understand if this design is, at all, close to the recommend specs, and also what this enclosure is tuned to.

Well ok then:

You need to learn what the front baffle is for, and why mounting the drivers to the inside of the enclosure doesn't work.

You need to understand cross-bracing is essential no matter how thick the cabinet's walls are.

You need to learn that port tuning is determined from the drivers T/S Parameters.

And I could go on.

Looks like you know how to wire speakers and amps, and cut plywood. But you have no concept of loudspeaker design. It is as much a science as it is an art form.

And realize that this site was created to help educate consumers against products such as yours.

So please, give yourself the necessary education to make your products better!

 

[TLS Guy]

Interesting speaker.

I have now had time to model it for you. Yes, the cabinet should be braced, that is the most important omission. It would have been better if the speakers had been front mounted.

Now your box inside volume should be around 0.5 cu ft with a port flared at one end with a diameter of 2.5" and a length of 5.8". I enclose the file for you to view.

It is actually a very nice speaker. Those are very good little drivers. When starting to build speakers building a full ranger is a very good way to start. Properly built that speaker will be far better than the majority of 0.5 cu.ft speakers talked about on these forums.

I would revise to optimize it, and I bet you will enjoy it for years. It will be well worth building a matched pair.

The fact is there are nowhere near enough full range driver designs on the market. In fact things would be much better if the majority of small speakers were full rangers. Those little units are among the best of them and there should be far my choices to design with this approach.

Despite my more complex designs of my later years, I'm a committed full ranger at heart. In my view every designer and especially transducer designer should be too.

The biggest pity in this whole filed is the plethora of restricted bandwidth drivers.

So stay engaged and perfect this design. This is probably the most sensible first design for a small speaker that has appeared from a novice all the time I have been on this forum.

 

[Hi-Fi Luggage]

Maybe try an aperiodic port for a taste of non-resonant bass.

Thanks for the suggestion, an no I do not have a speaker tester.

You need to learn what the front baffle is for, and why mounting the drivers to the inside of the enclosure doesn't work...

You're right, there is a lot to know, and most of it is loud speaker design. I'm learning that my original question is leading to other questions and is very difficult to answer. Side note: I've seen many projects use this driver and they mounted it on the inside, but it sounds like that's not ideal. I don't have the wood-working skills (yet) to create a notch for the terminals otherwise I would have mounted them in the front. Also, there are two, 1" cross braces (wooden dowels haha) evenly spaced that I hope will do something. The cabinet is quiet and vibration free. Lastly, I felt that those last few lines were a bit of a jab, considering what I make, and what the boombox I made here, is not intended to be a traditional loud speaker that you plop in your listening room. I think that is a belief many builders have...that all speaker projects need to have audiophile quality output, otherwise it's a waste of time. I will take your advice, though, and continue to learn about the correct way to design a loud speaker.

 

[Hi-Fi Luggage]

Interesting speaker. I have now had time to model it for you. Yes, the cabinet should be braced, that is the most important omission. It would have been better if the speakers had been front mounted....

Thank you so much for the detailed reply and for the kind words. So according to NA response graph, this boombox drops off around 55 Hz if the port size was different? Also, on page 3, what do some of those measurements mean to you? That was all new to me (just downloaded WinISD) and I'm trying to make sense of it.

Side note: There is some bracing, but I know it's not enough and not done correctly..hopefully it does something. The enclosure is quiet and vibration free. I have (2) 1" dowels evenly spaced from left to right side. And mounting the drivers in the front would require notches to be cut and I don't have the wood working skills to do that yet. Maybe I could have dremeled them out, oh well next time. Is there somewhere I could see some of the work you've done?

 

[TheWarrior]

Thanks for the suggestion, an no I do not have a speaker tester.



You're right, there is a lot to know, and most of it is loud speaker design. I'm learning that my original question is leading to other questions and is very difficult to answer. Side note: I've seen many projects use this driver and they mounted it on the inside, but it sounds like that's not ideal. I don't have the wood-working skills (yet) to create a notch for the terminals otherwise I would have mounted them in the front. Also, there are two, 1" cross braces (wooden dowels haha) evenly spaced that I hope will do something. The cabinet is quiet and vibration free. Lastly, I felt that those last few lines were a bit of a jab, considering what I make, and what the boombox I made here, is not intended to be a traditional loud speaker that you plop in your listening room. I think that is a belief many builders have...that all speaker projects need to have audiophile quality output, otherwise it's a waste of time. I will take your advice, though, and continue to learn about the correct way to design a loud speaker.

If you knew how often we had to sort thru the respectable people trying to gain knowledge, like yourself, with the 'snake oil salesmen', it would seem less harsh. But I do not mean any offense!

This site has a wealth of knowledge! Keep asking questions, post pics, engage! I myself am learning speaker design, and believe me, it takes a lot of studying to get it all down.

TLS Guy is extremely knowledgeable, and I recommend utilizing his info.

Welcome!

 

[Hi-Fi Luggage]

Thanks thewarrior, and I hear ya on sifting through the sneaky sales approach. Thoughts about if I ditched the port and installed a 6.5" passive radiator?

https://www.parts-express.com/6-1-2-high-excursion-passive-radiator--299-018

 

[TheWarrior]

Thanks thewarrior, and I hear ya on sifting through the sneaky sales approach. Thoughts about if I ditched the port and installed a 6.5" passive radiator?

https://www.parts-express.com/6-1-2-high-excursion-passive-radiator--299-018

Theres some math involved in selecting and properly weighting a passive speaker. So without running those numbers I cannot say: 1) whether a passive radiator would help and 2) if this particular model is what you need.

Have you tried resizing your port tube? TLS gave you exact dimensions, I would start there, first!

 

[ski2xblack]

A passive radiator performs the exact same function as a port tube and requires the same degree of consideration of driver t/s parameters and box volume. Also worth noting, the volume TLS calculated is greater than your existing cab. If you re-mount the drivers to the front of the baffle, which as mentioned above is advisable anyway, you may get closer to his recommended volume, but it's still probably a bit off.

Working with the existing cab, it would be nice to model it as sealed, leaky (aperiodic vent), and reflex, using the actual volume you're working with, to compare different approaches. Or you could build a new cab to TLS' recommended volume.

If you're going to pursue this, and it looks like you're already doing so since this is project #4, you owe it to yourself to get a copy of Vance Dickason's book or similar reputable speaker building reference.

 

[Hi-Fi Luggage]

I was able to change the port to this one. The length I am using now is 2.5 X 5.5: http://www.parts-express.com/parts-express-speaker-cabinet-port-tube-2-1-2-id-adjustable--260-386. I noticed immediately the low-end cleaned up and is louder at lower frequencies, with no port noise.

I haven't decided if I am going to front mount the drivers yet. Part of the reason I rear mounted them was to protect the drivers as this boombox is used outdoors on the play ground. It throws quality sound pretty far. Also, I was able to track down a copy Dickason's book via PDF so I'll spend some time with it.