Volume control questions

My first question is on the volume control and
Cancel assembly in the bottom rear/back of machine.

I see from photos online there are several resistors and
Capacitors in there, ( this is a rockola #414 ), can these
Cause a sound degradation if out of spec.? What might
This sound like? Amp has been rebuilt and sound is good,
But I never realized those were even in there and have not
Been looked at.

Second question:
Can there be a difference in sound quality if rear volume is
Turned up while amp volume is kept relatively low, or visa/versa
Back volume low, amp high?

I know on my guitar amp, if amp volume is kept low and guitar volume
Is cranked up you get that distorted overdrive effect.
Or is that a totally different application?

Just curious,

George Raven

The volume controls on those old R-O's are standard dual-tapped pots with a fairly heavy amount of bass boost at low settings.

If the capacitors lose value the sound will appear thinner at low settings. This is more a problem with Seeburgs which used paper caps in this application. R-O, at least the ones I've seen used plastic or mylar caps and these are generally quite stable.

As you turn the control up, midrange should gradually increase as you reach the 2/3 position. After that there is no boost and the caps are not in the circuit. If the midrange appears somewhat louder at the lower settings, then reduces at midpoint and then increases again, that would indicate that the caps on the lower tap have changed. Also if the two channels change and sound different as the pot is increased that too indicates a change in the components associated with the taps on the control.

I am not too sure what you are talking about re:"Can there be a difference in sound quality if rear volume is
Turned up while amp volume is kept relatively low..."

If you mean the internal trim pots on the amplifier, those are to set the level that the first stage delivers to the AGC/thermistor stage and yes, if they are set too high it will cause distortion.

The best way to set these is to adjust them so that a very loud record doesn't blast too much before backing down to average level. Try also to keep the channels balanced when adjusting these. It's a rather crude method of leveling various records. they could have done a better design but the emphasis was to keep it cheap and simple.

Has the amp been rebuilt? It should be.

Rob/NYC

Thanks rob.

On the volume controls, I'm meaning the volume on
The back rear/bottom, and the volume on front of
Amp next to treble / bass controls.

Would it be different with rear volume slightly up
With amp volume totally up. Or, rear volume up
All the way, with amp volume slightly up?

Im wondering which way might be cleanest
Sounding from your experience? Maybe it would
Make no difference?

Amp was rebuilt 6 mos. ago by Bill Bickers, I believe
Amp is working great.

Just wondering if there was a rule of thumb on
Those settings. I'm also sure I need to clean all
Volume pots real good.

Thanks,

George

If you mean the control that is marked "machine speakers" -that is a cross-fader to balance the machine speakers with externals. It is an ancient wasteful concept and I don't know why R-O was still using it in the era of 70volt remote speakers with tapped transformers.

Always set it to maximum level for the machine speakers and control overall volume with the one on the rear of the cabinet.

Rob

Rob,

Thanks, it is the one marked ' machine speaker pad',
On the amp that I was wondering about.

Always been curious about that
Thanks for info!

George