Vibrasonic unit

[hermitcrab]

Took out the unit to clean all the dust bunnies out and to replace the foam padding that it rests on... all crumbling away... anyone know what the purpose of the lightbulbs are for? They seem to be in parallel with 120 ohm resistors.. are they like some sort of fuse?, shows them in the schematic , but nothing for replacements...

[William]

I have the same thing in mine Elton, and have no idea what they are used for. I still need to do the restoration on mine so I have not bothered to check out there purpose. My Rogers 33E Theater Organ has light bulbs as well, and I have no idea what they do either.

Bill

[TC Chris]

A variable resistance is the best guess. I have read about using small lamps as a fuse on power transformers, too.

Chris Campbell

[electra225]

I'm not wild about this link, but it may help you guys with the Vibrasonic.

https://antiqueradios.com/forums/viewto ... 6&t=327013

[Firedome]

Norm Braithwaite knows what he's talking about, he's a true expert.

[electra225]

Tthere isn"t much on the net about the console version
There is plenty about the automotive version. The link I provided had the best explanation . I don't know Norm very well, but defer to his superior knowledge on this subject.

[Moto_TJ]

The lamps are called Compression lamps, I think their purpose is to dissipate excess energy that the reverb circuit cannot handle. I know if you turn the volume up they will light up on bass heavy parts.

[hermitcrab]

on the schematic they showed in the thread, the speakers were all in phase... the woofer on mine is not... I thought it might be a mistake , but the schematic also shows the bass woofer wired out of phase... anyone know what the purpose of that is?
Elton

[TC Chris]

on the schematic they showed in the thread, the speakers were all in phase... the woofer on mine is not... I thought it might be a mistake , but the schematic also shows the bass woofer wired out of phase... anyone know what the purpose of that is?
Elton

I read Stereophile magazine and their speaker reviews always report phasing of woofers and tweeters. They are often out of phase, intentionally. I think it's because the big heavy woofer takes a while to get going, and being out-of-phase electrically makes them in-phase sonically. It's a common design practice, not a mistake.

Chris Campbell

[hermitcrab]

Chris , I have a Fisher Regent console ... one of the mid-range speakers had a bad rub , so I replaced it and noticed the woofers on that are also 180 out of phase ...I never knew that was a thing that manufacturers do...