Post by jollyjon on Feb 20, 2022 13:42:36 GMT
I've got a 42 year old rock-ola 480 jukebox that had been resting in my garage unused for last 17 years (yeah I know - what a waste). After about 85 hours of trying to get it work recently (mainly the amp), I've got music. With RCA audio plugs in the amp (it was like that when I bought it in 2000), I play music but the sound quality is poor (even after testing capacitance and ESR of every E cap and replaced about 15 that didn't meet within the range it's supposed to be) and the loudness is .... not very loud - despite having 12in speakers. I feel my mini HiFi could be almost as loud (it has 6 in speakers) and it certainly sounds a lot better and it's about 20 years old. I got excited when it first started to play and I cranked it up expecting it would pump out a lot but the volume was only moderate. The quality was a bit muffled and it didn't have much high tones to hear guitar solos. I thought maybe the 8uF 35V crossovers for the 6inch speakers has worn and needed replacement but the ESR on those are on 1.5 which is really good for a 8uF E cap.
Hope someone can shed light on how to improve the quality and loudness or is this all I should expect from such an old audio system as I can't remember what it use to sound like all those years ago when I first bought it. I think it's a class A amplifier with 23VAC to 32VDC input voltage and supposedly 12VAC max output on each audio line. Now thinking about that, in next few days I should actually test the VAC while it's playing to see if it's at 12V while cranked up full. Sound quality is still an issue.
I did note the jukebox has a couple of technical flaws -
There is a bit too much hum that increases when the volume is turned up. I'm aware that a quiet hum is normal but it's a bit to loud to refer to it as quiet - it's kind of a bit annoying. Perhaps some kind of electrical interference in the amp itself. I have an extra amplifier (exact same model) and when I switch it, the hum is about 75% less (but I'm selling that amp).
When I switch the jukebox off it take about 2 seconds to cut off sound and during those 2 seconds the sound increases about 300%. It's as if the remaining charge in the caps tries to keep playing the music for those 2 seconds (the CD from different power source is plugged into the jukebox amplifier), but instead of just fading to silence in those last 2-3 seconds, it rapidly increases in volume. It's weird - but I'm far from a expert to figure out how or why it's happening. It's not a big deal but just curious to find out if it's connected to why I'm not getting as loud music one would expect from a jukebox with 2 x 12in and 2 x 6in speakers.
Any insight or feedback about these 3 issues would be great.
Hope someone can shed light on how to improve the quality and loudness or is this all I should expect from such an old audio system as I can't remember what it use to sound like all those years ago when I first bought it. I think it's a class A amplifier with 23VAC to 32VDC input voltage and supposedly 12VAC max output on each audio line. Now thinking about that, in next few days I should actually test the VAC while it's playing to see if it's at 12V while cranked up full. Sound quality is still an issue.
I did note the jukebox has a couple of technical flaws -
There is a bit too much hum that increases when the volume is turned up. I'm aware that a quiet hum is normal but it's a bit to loud to refer to it as quiet - it's kind of a bit annoying. Perhaps some kind of electrical interference in the amp itself. I have an extra amplifier (exact same model) and when I switch it, the hum is about 75% less (but I'm selling that amp).
When I switch the jukebox off it take about 2 seconds to cut off sound and during those 2 seconds the sound increases about 300%. It's as if the remaining charge in the caps tries to keep playing the music for those 2 seconds (the CD from different power source is plugged into the jukebox amplifier), but instead of just fading to silence in those last 2-3 seconds, it rapidly increases in volume. It's weird - but I'm far from a expert to figure out how or why it's happening. It's not a big deal but just curious to find out if it's connected to why I'm not getting as loud music one would expect from a jukebox with 2 x 12in and 2 x 6in speakers.
Any insight or feedback about these 3 issues would be great.
