# New project: 80s Emerson Boombox!



## K2e2vin (May 18, 2009)

I had this sitting in the shed and thought I'd recondition it. It works completely fine and I've already ordered another boombox that's cosmetically sound to swap the guts. I've also thought of integrating an iPod dock but I may just use an external one instead since it would hit the handle when mounted on top.

I'm wondering, would there be a way to improve the sound while I have it apart? Maybe a more efficient amp(bypassing stock amp, since it can run off of 12v/D batteries in series) and possibly replacing the speakers? Though I haven't tore it down and not sure how it's amped(due to the EQ and separate volume channels).

I'd like more bass(so I can turn up some Afrika Bambaataa and whip out the track suit  ) but as you can see, you can't really fit large speakers compared to other boomboxes of that generation.

As for replacing the amp; I'm not new to electronics(soldering, etc.) so that is not a problem, but I just don't know how to go about finding a more efficient amp(assuming there's one much better than this one made in the 80s). I'm still waiting on the "spare" boombox to take measurements and use as a mock-up.


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## BowDown (Sep 24, 2009)

Given the whole thing is constructed of plastic maybe some sound deadening is in order. Could try stuffing the chambers with polyfill? It's going to be tough to integrate a new amp into the mix as the original amp is prbly integrated into the pre-amp circuit.


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## XtremeRevolution (Dec 3, 2010)

BowDown said:


> Given the whole thing is constructed of plastic maybe some sound deadening is in order. Could try stuffing the chambers with polyfill? It's going to be tough to integrate a new amp into the mix as the original amp is prbly integrated into the pre-amp circuit.


x2 on this!!! Your actual sound quality will be severely limited because its made of plastic. There's a reason why high quality speakers aren't made of plastic, and BOSE is not high quality. The most recent project I'm building uses a 1.25" thick front baffle made of MDF.

With regard to SQ, you may look into replacing some of the capacitors with higher quality ones. Mouser.com will have what you need in that regard. Old electrolytic capacitors eventually dry out and need to be replaced as sound quality suffers. As for amps, look into the DIY class-d amp boards. 

These comes with a power supply as well.

2*[email protected] TK2050 ClassD Audio Amplifier Upgraded + 27VDC 13A 351W Power Supply (AA-AB32181 + PT-IP012)_Audio Amplifier Boards_Audio Amplifier and other Audio Boards_Audio, Video Equipments_Sure Electronics' Webstore
4*100w TK2050 Tripath Audio Amplifier + 27V 13A 351W MW Power Supply(AA-AB33182 + PT-IP012)_Audio Amplifier Boards_Audio Amplifier and other Audio Boards_Audio, Video Equipments_Sure Electronics' Webstore

Not sure how you'd hook up the tuner or the rest of the buttons available on the original unit, but its something to look into if you're inclined. This would also make connecting an ipod a cakewalk.

I honestly think you'd be better off building your own portable ipod boombox with one of these amps unless you have some sentimental or nostalgic attachment to these old ghetto blasters.


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## alm001 (Feb 13, 2010)

I want to do more of this! I've done it once, and I played Afrika Bambaataa on it at an 80's party.


Pics are here: https://picasaweb.google.com/alm001/LenoxxSound#









I used a dell computer speaker amp, some 9v batteries (F those D-cells)
I was really surprised by the volume I got with the 80's speakers and a more modern amplifier.

I have some Dayton RS100's under my desk in case I want to take it to the next level this summer, but it works great.


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## K2e2vin (May 18, 2009)

I love the way these boomboxes look and I don't always use the iPod(big fan of the FM tuner; and mic input for karaoke! lol). The boombox already has an audio-in jack, I was just interested in just wiring in an ipod connector(using line-out instead of the headphone jack). When I worked at UPS, those HU/iPod "boomboxes" were popular with the drivers but it just wasn't aesthetically pleasing. I'm sure it's possible to make it pretty(not wood/carpet or metal) but I already have something I like.

Thanks a lot guys! I'll definitely try filling the case and replacing the caps.

I'll be disassembling the circuit sometime tomorrow if I have time; I hope it's not integrated. But, if the circuits are on the same PCB but separate, so to say, that's not an issue at all.


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## BowDown (Sep 24, 2009)

Don't make it too heavy.. you wont be able to carry it on your shoulder. :lol:


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## K2e2vin (May 18, 2009)

alm001 said:


> I want to do more of this! I've done it once, and I played Afrika Bambaataa on it at an 80's party.
> 
> 
> Pics are here: https://picasaweb.google.com/alm001/LenoxxSound#
> ...


Sweet! Though, how long does it last with the 9v batteries? 



BowDown said:


> Don't make it too heavy.. you wont be able to carry it on your shoulder. :lol:


lmao!


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## BowDown (Sep 24, 2009)




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## XtremeRevolution (Dec 3, 2010)

For wall padding, I would recommend one of two options. 

The first is fiberglass insulation, the pink stuff from home depot. This is actually the material that has tested best out of all other commercial acoustic foams and polyfill-type substances. However, you need to wear gloves, and you need to use contact cement from my understanding, which not only emits tons of harmful fumes, but takes a while to attach. You need to paint it on both surfaces, wait 15 or so minutes, then bond the two together. 

The second is acoustic foam. PartsExpress sells it:
Acoustic Foam 1-1/2" 24" x 18" UL 94

I actually used it on my brother in law's speakers that we just finished building:
My version of Don Radick's AURBACS - Techtalk Speaker Building, Audio, Video, and Electronics Customer Discussion Forum From Parts-Express.com

This can be adhered with 3M adhesive spray. It actually works extremely well, and its very light. 

You might look into upgrading the input capacitors to larger ones to potentially improve dynamic range.

For replacement electrolytic caps, go with either Nichicon audio grade, or Panasonic low ESR caps.


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## K2e2vin (May 18, 2009)

I'm actually very familiar with insulation and acoustic foam(I've helped with construction including a "padded room" for recording); though I was thinking of using the filling material they use in subwoofer enclosures. Which would work best? I know there's also the foam boards used in conjunction with insulation but I'm sure those do not work well for sound?


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## BowDown (Sep 24, 2009)

Ya just your standard poly fill from a craft store will do it. That along with the dynamat style material to take the resonance out of the plastic.


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## XtremeRevolution (Dec 3, 2010)

BowDown said:


> Given the whole thing is constructed of plastic maybe some sound deadening is in order. Could try stuffing the chambers with polyfill? It's going to be tough to integrate a new amp into the mix as the original amp is prbly integrated into the pre-amp circuit.


As long as its open cell foam and its not too thick, you can use it. I wouldn't go over 1.5". 

As for the new amp, it can be done easily. Get a high level RCA converter for a car and wire that up to the speaker outs on the original amp. Then, add a switch somewhere so you can run either the pre-amp circuit or a 3.5mm aux jack for an ipod. 



BowDown said:


> Ya just your standard poly fill from a craft store will do it. That along with the dynamat style material to take the resonance out of the plastic.


Polyfill is TERRIBLE for use in speakers. For subs it might be fine, but for speakers, it is the absolute worst material you can possibly use aside from using nothing at all. I don't know how many speakers you've built, but I've attempted to use polyfill on several occasions, from lightly filled to heavily stuffed, and the results were always terrible. It also tests terribly compared to acoustic foam and fiberglass.

Lightly stuffed gave me better bass but did not eliminate the standing waves and caused serious distortion in the lower midbass range, and heavily stuffed all but eliminated my bass output. I started using fiberglass insulation and acoustic foam and never, ever went back. 

Its not just about resonances or increasing the effective size by slowing down the sound waves, its also about eliminating standing waves so they don't bounce back into the driver and create distortion. It does make a pretty big difference. 

Save your money, skip the polyfill and dynamat (or equivalent), and just glue on either acoustic foam or fiberglass fill.


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## BowDown (Sep 24, 2009)

Well I haven't done much in the way of speaker boxes that aren't subs. You are correct in that. All I know is the acoustic foams don't work as well as the poly in that situation. Waves being longer I guess would account for this. 

Anyway, carry on.


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## ryomanx (Feb 18, 2011)

a little bit off topic but has anybody seen this new tdk boombox?









I've been thinking about upgrading the speakers in my box as as well. Right now it's just got a line in I soldered in and I made special tape case for my nano.


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## XtremeRevolution (Dec 3, 2010)

Looks like there's a lot of improvement to be made with these given the right drivers. Just keep in mind that you will need to thoroughly dampen the walls of these boxes to make them sound good once you start increasing bass output.


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## XtremeRevolution (Dec 3, 2010)

BowDown said:


> Well I haven't done much in the way of speaker boxes that aren't subs. You are correct in that. All I know is the acoustic foams don't work as well as the poly in that situation. Waves being longer I guess would account for this.
> 
> Anyway, carry on.


Yeah, it really starts to distort your midbass. I keep a couple bags of it on-hand anyway for when I build sub boxes that benefit from it.


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## alm001 (Feb 13, 2010)

2 9v batteries will last at least 2 days of beach use. Haven't given it a "Thorough" testing

But I know its wayyyyyyyyyyyyyyyyy cheaper than buying 8 Dcell batteries.
My previous iteration used the original amp, and cost $20 to fill up.


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## K2e2vin (May 18, 2009)

Thanks for the tips and suggestions guys!

Should I separate the speakers and fill the enclosed speaker area or should I just dampen/fill the whole case?

Here's a picture of the inside I found btw:









Also, should I switch to an oval speaker setup(moving from 3 drivers per side to two) or should I just replace the drivers with different units(maybe something closer to a component setup; can 4" speakers go pretty low?) with a passive crossover?

And as for the battery, I think I'll stick with D-cell since I already have a lot of them(due to my flashlights using the same size) and they should have higher capacity than the 9v cells(drive them at higher volumes longer  ). I may try using a rechargeable battery pack or something later on.


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## Fus1on (Feb 25, 2011)

Cool project, i'm interested in seeing where you go with this 

I recently sold this on eBay, it had a handle on it (mine was missing the handle) and at 35 lbs was considered to be portable waaaaay back in the day .... Maybe the 1st ever boombox and it used a horn speaker lol
Antique 1924 RCA Radiola Superheterodyne AR-812 | eBay


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## XtremeRevolution (Dec 3, 2010)

K2e2vin said:


> Thanks for the tips and suggestions guys!
> 
> Should I separate the speakers and fill the enclosed speaker area or should I just dampen/fill the whole case?
> 
> ...


You're going to need to line the walls, not stuff the whole speaker. You want to keep those walls from resonating in addition to breaking up standing waves. 

As far as going lower, you're going to have some serious issues making it sound good with a thin plastic case. That was never designed to produce a large amount of bass. 

Your replacement driver options are very limited as there aren't a whole lot of affordable 4" drivers that sound good full range. 

These are the only drivers I'd actually recommend:
https://www.madisound.com/store/product_info.php?cPath=45_241_282&products_id=1372
https://www.madisound.com/store/product_info.php?cPath=45_241_282&products_id=8781

The TangBand has a much better top end frequency response, but they both sound great and the NS3 has amazing bass output for such a small driver. I can't stress enough though that you will need to dampen the walls extremely well.


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## K2e2vin (May 18, 2009)

You think cuts of acoustic foam would work? The case has some raised areas so putting a board would take up too much space and I'd still need to fill the cavity between the board and plastic with fiberglass. I may still use a board to separate the speaker area and the PCB board. I don't think the bass would be *that* strong since it's a 4" driver in a portable setup.

After taking a look at the amp section(the OE speaker are rated 4W each but I doubt they get anywhere close to that); I'm definitely going to swap in another amp; hopefully I can tuck it away behind the EQ. Would there be a noticeable difference between AB or D? I'm going to hook the speakers up to a crossover also.


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## XtremeRevolution (Dec 3, 2010)

K2e2vin said:


> You think cuts of acoustic foam would work? The case has some raised areas so putting a board would take up too much space and I'd still need to fill the cavity between the board and plastic with fiberglass. I may still use a board to separate the speaker area and the PCB board. I don't think the bass would be *that* strong since it's a 4" driver in a portable setup.
> 
> After taking a look at the amp section(the OE speaker are rated 4W each but I doubt they get anywhere close to that); I'm definitely going to swap in another amp; hopefully I can tuck it away behind the EQ. Would there be a noticeable difference between AB or D? I'm going to hook the speakers up to a crossover also.


No noticeable difference, but class D will get you more power and run cooler.

I think cuts of acoustic foam or fiberglass insulation are about the best you can do at this point with what you have.


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## gregory_ (Sep 7, 2011)

Emerson! That brings back some memories!


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## Old Skewl (May 30, 2011)

Reminds me of my Aiwa Boombox I bought in the early to mid 80s(seems I remember paying around$300-400 at the local highend shop.) It had detachable wooden speakers that ported into a passive radiator in the bottom of the base. Boy did that thing sound good for a boom box. Heavy as heck though! Electronics crapped out in the mid 90's. Nobody would fix it. Went in the trash.


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## Old Skewl (May 30, 2011)

Finally remembered what is was:

Aiwa CA-70.


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