80's boomboxes - how did they power the amps?

[Yves Smolders]

I'm looking at some old 80's ghettoblaster/boomboxes which could play really loud just running of 8 D cell batteries (12V)

How did they power the amplifiers in these days? I don't believe there was SMPS in these days, so what did they do then?

Reason I'm looking into this is to give old ghettoblasters "new guts", running class-d into improved drivers...

Thanks for the feedback.

 

[maxw]

They are powered by STYLE!

Seriously though, I don't know the answer, but post some pics of your work when finished!

 

[paulb]

Probably 4 ohm speakers, amp driven into clipping. Distortion makes music sound loud when it isn't really. Car radios could play really loud back then too, and only on 13.8V.

 

[theAnonymous1]

Don't forget about the high Qts paper cone drivers with decent efficiency.

 

[AP2]

Unfortunately or..fortunately, the power is not an absolute measure.🙂

 

[richie00boy]

Actually just 1 or 2 watts sounds pretty loud. I don't think class-d will give you any noticeable benefit in this situation.

 

[UncleArt]

Upwards of 8-10% THD
+ battery life measured in minutes.
+ very aggressive tone controls
+ fairly low-fi sources to begin with, i.e. commercial radio, cassettes, 8-tracks
(maybe 55-60 db SNR

Square waves are LOUD.
No one said they sounded good, but they're attention-grabbingly LOUD.

Ask your local commercial FM station.

Or worse, commercial AM station.

regards

art

 

[xeclipse]

I have a dead 90's one,TEN size D cells.Bi amped stereo (4 channels) 7.5 watts each,and my dad swears 'its the best music system ever bult'.I never got the chance to have a listen,but i hope i'll get it back to life.

 

[Yves Smolders]

They are almost mythical, aren't they? 😛 Well I'll get a hold of an old lasonic l-30m soon...

I'm far from an electronics guy myself (only slapped together a UCD amp, that's it) but I'll open it up and post some pics of the guts - we'll know soon enough what's in there. 🙂

What I'm thinking is just to put some very small class-d amps in there, some rechargeable batteries (don't know what type yet) and see if I can connect a portable MP3 player to it. 🙂

 

[Th3 uN1Qu3]

Probably 4 ohm speakers, amp driven into clipping. Distortion makes music sound loud when it isn't really. Car radios could play really loud back then too, and only on 13.8V.

I've had a few on hand that were LOUD even before clipping. You're right with impedance - i've seen custom 3.2 ohm jobs on one. Also the drivers were wound with as small of a space as possible between magnet and coil (i forgot the technical word but i'm sure you know what i mean), and also they used as thin wire as possible. 2 more watts than what they were rated for and the speakers would blow.

This is how they could get upwards of 95dB/W AND also the reason why the speakers' voice coil would invariably start rubbing against the magnet if played too loud for too long.