Modified Ampro for use with an external amplifier

[Patrick Ryan]

Hi again,
I recently brought 3 Ampros for a bargain price. Still testing the two Stylists. Already advised by you good folk on the first one, on a sound problem. Now on the second one, which has been modified, with the original amp stripped out, and a new HLX 15volt projector bulb replacing the old system. The photocell is neatly fixed in a wooden ! cork like component and is wired direct to a lead with a 6.5 jack, which plugs into an external amplifier. I have tested it on an old Cub 7 guitar amplifier and the sound is working okay, but not much volume at all, okay if you were actually sitting by the amplifier! I wonder how I can vastly improve the volume? Would a more quality amplifier do the trick? Any help appreciated.

[Nick Regan]

It could be the actual output level going into your combi amp is switched to the incorrect level on your amp. try it in the line in socket with the amp switched to line, or the same with the phono socket failing that try it in the microphone socket switched to mic. make sure the volume is down to start with then gradually increase it.

The level required on each of these input signals is different and the curcuitry to deal with them on the amp is geared differently, if plugged incorrectly it could result in either a distorted or a low sound.

let us know how you get on

Nick

[Nantawat Kittiwarakul]

What type of that photocell in use?

AFAIK for solar-cell pickup the output level would be more or less the same as microphone output level. That means you should be able to input that directly to any sound system with microphone input. Some resistor would be necessary to tame out the varying output current (forgot the recommended value at the moment, maybe trial & error?) At least that's how I once get the audio from my 35mm projector optical pickup.

But for another type of pickup...that's another story.

[Patrick Ryan]

Thanks gents, will try. The Cub 7 is a very basic guitar amplifier for kids I suppose, with just an input jack and a phones socket! only brought it for a song to test the projector. Anyway wait out! The photocell is a small rod, pencil like object embedded into the wooden cork that slots into the photocell/ exciter recess. Homemade.. However it seems to be working well when rotated for best response...

[John Burgess]

Hi Patrick, you could do with picking up a PA amp say about 15/20 watt output ; then plug your cell lead straight into the mic socket input, should work no problem. Have done this myself on a few occasions and it never fails.
good luck John

[Patrick Ryan]

thanks John, will try that

[Nick Regan]

Patrick,

I have just got 2 x complete Ampro Premier 20 Systems, I have only plugged them in so far as I am running around trying to get ready for Blackpool. One of the machines has a loud hum when the motot is running. Looking to save some time, and with you being currently playing with Ampro amps, have you come across the motor suppression curcuit on these things.

I will eventually get time to concentrate on them and strip them down, just wondering if there was a "quick fix"

Nick

[Patrick Ryan]

No sorry Nick I haven't. As yet I haven't got around to the Premier 20. I have intelligable sound now on the converted Stylist number 1, after running it through a cheap amp as a test. So I am assuming that a decent amp would do the trick now.
On my other Stylist, (number 2) which is a straight forward unconverted model, I can get good hum feedback from the speaker, the exciter lamp is working and I can get a slight plopping noise from the photocell, but still no evident sound on running a film through. So I am unsure what to do next. As you know the amplifier in the Stylist is a nightmare to play around with, even replacing caps needs the fingers of a four year old, so I am loathe to touch what I am unsure of anyway! Any advice would as always be appreciated.

[Nick Regan]

Patrick, Did I send you the ampro service manual? I am just about to get "Heavy" with a pair of the Premier 20 machines, I have sold the stylists I had and am now left with a New Educational machine, the 240 vac version of the Stylists, which has a beautiful amp and sound, a silent Imperial and at last count 3 x Premier 20's. I should be able to let you know how I get on when you get round to your Premier.

As an operational sound engineer in my younger days I feel the sound level problems you are having are caused by the original signal size from the machine. An amplifier will amplify anything that it has going through it but the input signal type is dealt with differently.

If possible I would suggest getting hold of an old sound mixer, one that has seperate eq on each channel, test the input by selecting the different imput modes 440mv- old line level 770mv new line level - 2v CD level - microphone level power mic level, phono - gramaphone level.

Each signal type is dealt with seperately with pre amps ricc etc so the output will sound different, oh, and the old favourite, dont plug an amplifiers output into another amp input or amplify from a headphone output.

Let me know

Nick

[Patrick Ryan]

Yes you did send me details of the service manual thanks. I have got one now. thanks for the other info. I will soldier on with that info!

[Patrick Ryan]

Reference the Ampro amp problem, problem solved with using mic input on an external amp. Thanks to you all for your help.