Giving a old ghettoblaster a new lease on life (progress build)

[3rutu5]

As some of the other posts may have mentioned previously, i'm currently doing a few things with some Sharp gear found locally and digitally online. One was picking up an old SHARP GF5454 for 40 AUD, granted it didnt work and was being used as an display piece, i thought would it be cool to get it functioning as a boombox. The challenges are

1.Annoying the collectors out there by not keeping it stock, which also has prevented me from painting it as it has some nice labelling i dont think i can reproduce which would take away its charm without.
2.using some of the existing swtiches if possible
3.not cutting the external body of the unit.
4.powering it via Li-ion
5.putting more powerful drivers in it
6.using the existing tweater holes
7.having a working radio
8.keeping some functionality of the tape deck

there are probably more, as unlike my other builds im a bit torn with what to do as i've wanted a blaster since i was a kid growing up in the 80's and to find out that its a year younger than me, purchasing this was a dream come true.

First step was to find a good driver as i couldnt fit a decent tweater in the existing housing, which i ended up using the RS100-4 thanks to the feedback from the group.Once i figure out how to put in a divider, the internal volume with be roughly 0.15cuft each side with a box tuning to 70hz giving an F3 of very late 50's but close to a 3db bump. i went with a port that was a similar cross sectional area to a 1 1/4 dia vent, but had a thought when about to cut into the plastic, with reusing the existing vents in the back. I dont quite get what these big vents were for back then, but 3d printed something that looks like it would get star trek fans excited.

[3rutu5]

The 3d printer has been getting a bit of a work out again as first step was to design/print a housing that the RS100 driver could easily bolt into, whilst still using the existing speaker mounts. Success! i was also thinking that as i was rear mounting these drivers that i would give it a bit of a flare, which would also give the speaker a bit of clearance from the plastic front. This entire process was a bit of a mission as the calipers didnt really fit to get the measurements as close as i would normally do.

It also just so happens that i had some nice black M3 and M4 bolts that being 20mm long were perfect for both the mounting to the faceplate and the driver to the print. Even though the drivers are a bit smaller in diameter to the original speaker, im hoping these will pack more of a punch (looks like a first run of the old would have shredded them, they had a hard life).

[3rutu5]

VENT TIME....this process took 3 attempts and 30 hours of printing (due to the reworking), not to mention a few cracks in AutoCAD. As mentioned above, the suggestion from the group was to use a 1 1/4inch diamenter port that was 4inches long, which was giving me some challenges due to me wanting to 3d print it and also being in a metric country where a 31.75mm pipe wasnt readily available......so CAD time and printing was of course the avenue i took. I'm sure i could have just used a 30mm piece of PVC pipe and called it a day, but it would have meant i'd have to drill into the body, which i didnt want to do, without painting the frame. Also to note i was originally intending to print some discs to cover up those rear grills/vents, but ended up with the below to both use the existing openings and solve the port issue.I've matched the same cross sectional area but going a wider and slightly lower height with the end result having about 5mm between the magnet of the driver and the top of the print.

I would like to know if anyone sees an issue with have basically a grill over a port, i've done it before on the lowfi projects, but never on something of this size. They dont looks too restrictive, so fingers crossed they will be fine.

[3rutu5]

Still plenty more to come,

amplifier will be a Wondom JAB one, which is a 2x50w variant with DSP on the unit itselt (identical to the DA KAB board) and i have a Dayton Audio LBB3 in the garage as well which i intend to use as the BT/AMP doenst have the charging circuit.

If anyone has used the LBB's, i would be interested to know if it has more than one output on it, i've been looking and a bit confused, but would be wanting to put a RGB strip from a PC Case into this somehow (or a 5v version). One thing i'm not sure about if i could use any of the LED outputs from the boards, or if i have to hijack a lead somewhere. I did see a youtuber called Modine has done a boombox recently using the DA products and had flashing lights on it, but dont know how he did it. Gimmicky i know, but i still would like it.

[Chris Roemer]

brutus, you are one odd fellow - and come up w/some VERY weird ideas (that seem to entertain you), but your work is AWESOME (and always interesting to read about). Thanks for your participation !

[3rutu5]

Weird indeed, sometimes practical...my wife got in my head with this one and told me that if i paint it, i would surely stuff it up and waste 40 bucks....so this one on the surface at least will be true to its roots.

[Brian Steele]

Nice work!

Piezo elements might fit in those tweeter housings. OTOH you could just Dremel out the little "waveguide" thing in the tweeter mount, which should leave enough space to mount a small tweeter (hot-glued in).

Did you consider using PRs mounted to some standoffs (so they wouldn't hit the back of the enclosure) instead of vents? This would allow experimenting with a lower Fb and a "B6" type filter for the main drivers to provide a bit more than the expected bass from them. The biggest problem IMO I think you're going to run into though is how to properly seal that plastic body to actually get that low bass reproduction (through vents or otherwise).

[3rutu5]

Nice work!

Piezo elements might fit in those tweeter housings. OTOH you could just Dremel out the little "waveguide" thing in the tweeter mount, which should leave enough space to mount a small tweeter (hot-glued in).

Did you consider using PRs mounted to some standoffs (so they wouldn't hit the back of the enclosure) instead of vents? This would allow experimenting with a lower Fb and a "B6" type filter for the main drivers to provide a bit more than the expected bass from them. The biggest problem IMO I think you're going to run into though is how to properly seal that plastic body to actually get that low bass reproduction (through vents or otherwise).

Not really with the PR's I thought the size of the existing vents was maybe 4.5inches and that trying to make it air tight would be a nightmare. Has so many little holes and openings.

Very good point and I didn't think of it, vented or not the body is only 2mm thick, so not sure if this would vibrate. The hardware store has some few mm thick rubber sheets maybe j could investigate further, ie line the insides with it.

To date I was only thinking about how much of a pain it would be to design a divider due to all the little things on the inside...and was trying to figure out what the noticable difference would be if I didn't.