I made a boombox

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
An she is pretty. I took the bling off a Helix 4636 and built a new body.
I did no math. None, lol. But she pretty?

I had a Lvpin 2020A+ amplifier in it, and I was happy enough with the result... I'm not sure if the Lvpin has a genuine tripath chip.

But - I was in the shed rummaging and found a 41hz Amp32 from years ago.... and now the box is singing. It's so nice.

sBLmRgT.png


G36Z5rB.png


I stole this guys clothes

wCzxPO7.png


Initial mockup:

srasyoI.png


I bought the Helix back in 2004, and modified it several times with different speakers, but it never sounded right. In 2008 I bought these Visaton B200's, and fitted them into the plastic shell of the boombox, but it never sounded good. So 2019 I have the solution.

The box is unfinished. I think I'm going to wood veneer it, I need to seal it, these are things I have not done before.
I bought a bluetooth module for it, I might put DB needle meters on it, not sure. The next thing to do is to fill the box with seeds or rice or something, to measure the volume. I can rebuild the box to get the optimum volume for the B200's

The B200's are pleasing me at low and medium volumes, very pleasing. More bass at increased volumes would be nice.
I have been looking at the Dayton Audio PS220-8 full-range, with the hopes of building a box with better bass. I'm going to spend some time with it as it is though.

So yeah. That's that. Thank's for reading.
 
Last edited:
The next thing to do is to fill the box with seeds or rice or something, to measure the volume. I can rebuild the box to get the optimum volume for the B200's

The B200's are pleasing me at low and medium volumes, very pleasing. More bass at increased volumes would be nice.

Nice work!

Optimizing the interior volume for the Visatons should fix this or at least get them closer to what you want.
 
Thats nice of you to say man. I'll disassemble it this week and get the literage. Perhaps you guys would be kind enough to direct me from there, as to what volume would be suitable?

I have been massively enjoying this speaker. The B200's are superb I think. Worth the money, all day long
Deff one of the better things I've ever built. I build a lot of stuff that never gets used, because I have a need to burn energy. This is getting heavy use, which is a relief,
not everything is a folly.

TsCyL20.png


wZ1lgYD.png
 
Last edited:
So I measured the box at 25.2 litres. Can anyone advise what would be the ideal for 2x Visaton B200 speakers, please?

krfKBF0.png


I applied a woodstain to the box also, I like it so far, but its not finished, I'll post some pics when its assembled and cleaned up.
 
Visaton recommend a closed box volume of 70 litres for a single B200 because it is a high Q driver.

B 200 - 6 Ohm | Visaton

70 litres is equivalent to 2.5 cu ft which would be rather large for a boombox!

Instead of a closed box you could use aperiodic loading which would permit the use of a smaller box volume.

Please confirm whether each B200 has 25.2 litre of volume available to it, or if this volume is shared by both the B200s, and we may proceed further down the design path.
 
@Galu, you are a legend, thank you sooo much.

The interior volume of the box without the speakers is actually 24.8 litres (predicably I miscalculated)

So the 2 speakers are going to take up some of that space.


From what I understand of aperiodic loading, its basically a leaky box? Or is that heresy, apologies if it is.

I'm about to go drinking so wont be around for repies for this evening, thank you again for your help, its needed! Pic of my garden set

3Yys71E.png
 
The interior volume of the box without the speakers is actually 24.8 litres
OK, after looking at your volume measuring photo, I will assume that each B200 presently has a volume of approximately 12 litres available to it, or approximately 0.4 cu ft.

Using your existing boombox design, you could experiment by resistively ventilating the solid backs of your two B200 enclosures. If this improves the sound then well and good, if not you can always return to solid backs.

By my calculations, here's what you have to do to each of the two speaker enclosure back panels:

Drill 5 rows of 4, 1/2" diameter, holes through each back panel (That's 20 holes per panel.)

The centres of the holes should be spaced 3/4" apart.

Cover the holes on the inside of the back panels with a felt cloth like that used in winter overcoats.

Line the side, top and bottom interior walls of the enclosures with a thick absorbant material like fibreglass.

You have now made aperiodic enclosures! P.S. Make sure the rest of the enclosures (apart from the ventilated backs) are airtight.
 
Last edited:
Account Closed
Joined 2018
A centrally located port tube near the bottom, below the amplifier, going through the amp mounting panel, might be a good way to extend the bass.
I've built a stereo radio with such a port out the rear, and it enhances the bass quite nicely.
Make the port about 20 to 25 CM diameter, flush with the interior area behind the amp board, and flush with the rear panel.
Alernatively, a "slot" could be designed across the bottom of the amp board - the full width of the amp panel, and perhaps 15 CM high inside dimensions.
 

Attachments

  • RADIOFT.jpg
    RADIOFT.jpg
    13.7 KB · Views: 97
  • RADIOBK.jpg
    RADIOBK.jpg
    12.2 KB · Views: 101
  • RADIOINSIDE.jpg
    RADIOINSIDE.jpg
    21.7 KB · Views: 93
The high Q of the B200 makes it unsuitable for reflex port loading and diy buffs use large sealed enclosures, slightly smaller aperiodic enclosures or open baffle mounting.

Consequently, a B200 is not the best choice for a boombox application and any suggestions we may offer are unlikely to significantly enhance the bass performance in such a small cabinet.

Still, it may be fun trying to do so before spending money on more suitable drivers. :)
 

Attachments

  • B200 Aperiodic.jpg
    B200 Aperiodic.jpg
    26.6 KB · Views: 102
PRR makes a valid point and you did say that the B200s were pleasing you, except at high volumes.

If you do wish to experiment with resistive venting then, using a router, you can cut out narrow slots in each of the backs instead of drilling holes.

4 slots in each back, each 4" x 1/4", will do the same job as the 20, 1/2" diameter, holes I suggested earlier and will produce a neater finish.

As I said, it will be easy to revert to solid backs if the resistive venting does not prove to be of advantage. Nothing ventured, nothing gained! :)
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.