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jhewes

Inputs on Scott 299C

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On my Scott 299C amplifier, I have the following inputs on the input selector knob:

Mic

NAB Tape

RIAA NAB Ortho

Tuner 

Extra

 

On the back, I have the following RCA connectors:

MAG 1 High

MAG 1 Lo

MAG 2 High

MAG 2 Lo

Tuner

Extra

Recorder

Playback

Headphone

 

I'm having some trouble reconciling the front of the unit with the back, in other words I can't match up the inputs on the rar with the positions on the selector switch.

 

Tuner and Extra are easy. These are line level inputs with matching positions on the front selector knob.

 

RIAA NAB Ortho is the phono input, either 1 or 2 as selected on the slide switch, and either lo or high level.

 

The Playback input is heard when the tape monitor switch is IN, no matter the position of the input selector knob. This is a line level input.

 

I hear the RECORDER input no matter what position the input selector knob is in, and this appears to be a line level input. Is this normal? What is the function of this input?

 

I hear nothing on the NAB TAPE and MIC positions, and find no correlating RCA inputs on the back of the unit. What are these inputs for?

 

Is the HEADPHONE an output on the back for headphones? These are two R and L RCA connections. There is also a 1/4-inch headphone jack on the front panel. 

 

Any assistance is much appreciated. 

 

 

 

 

 

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The "Recorder" jacks may be a line level output for a tape recorder.  If you are sending signal into these jacks, then you will hear that signal regardless of which input you use.

 

The idea behind the inputs is that the tuner and the extra are what we would consider "line level".  The magnetic input would be a moving magnet phono cartridge, or magnetic tape heads, with Mag Low being the appropriate impedance for a moving magnet phono cartridge, and Mag High being a higher impedance input for tape heads.  

 

NAB Tape and RIAA/NAB/Ortho selects an adjustable EQ.  The presence of the Mic option would lead me to believe that this selection is for no EQ on the magnetic input.

 

Are you 100% sure that you hear nothing with Mic selected and sending signal through Mag High?

 

On the 299D (the only readable schematic I could find was for the 299D), there is a switch for speakers on/off.  Turning the speakers off disconnects the rear panel speaker jack connections, and instead connects a resistor across the output of the amplifier.  This will stabilize it with no load.  The headphone output is taken from the 4 Ohm tap and fed by a few 150 Ohm resistors.  This worked pretty well back in the day when headphone impedances were pretty high, but will give you pretty mediocre performance with today's low impedance headphones.  A better choice would be to add a 10 Ohm resistor from ground to ring and ground to tip on the headphone jack, which will clean up bottom end performance and fix the output attenuation a bit better. 

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On ‎10‎/‎11‎/‎2016 at 10:49 PM, jhewes said:

On my Scott 299C amplifier, I have the following inputs on the input selector knob:

Mic (this along with NAB Tape and RIAA NAB Ortho is part of the Mag inputs by choosing one the preamplifier applies the proper EQ curve for that type of source you have plugged into the Mag 1 or 2 inputs)

NAB Tape See above answer

RIAA NAB Ortho see above answer

Tuner 

Extra

 

On the back, I have the following RCA connectors:

MAG 1 High  Used for unamplified magnetic sources with 6mV or more of raw signal almost never used today

MAG 1 Lo same as above but for 2mV to 5mV of signal

MAG 2 High Used for unamplified magnetic sources with 6mV or more of raw signal almost never used today

MAG 2 Lo same as above but for 2mV to 5mV of signal

Tuner Line level source

Extra Line level source

Recorder Unaltered source signal for recording purposes

Playback Play back from an amplified tape deck (not magnetic tape head) This input can be used as a 3rd line level. You use the tape switch in the "In" position to listen to this input.

Headphone In most cases the head phone jack/or these RCA jacks on this and any earlier produced Scott are not very useful since they gave you no way to turn the speakers off. To use them you have to provide dummy load on the speaker terminals or have speakers attached. But the 299C had no less than 7 different versions one version actually had a headphone jack on the front that when plugging in the headphones the speakers would shut off and have the proper load in place. Its not common but I've seen a few of them.

 

I'm having some trouble reconciling the front of the unit with the back, in other words I can't match up the inputs on the rar with the positions on the selector switch.

 

Tuner and Extra are easy. These are line level inputs with matching positions on the front selector knob.

 

RIAA NAB Ortho is the phono input, either 1 or 2 as selected on the slide switch, and either lo or high level.

 

The Playback input is heard when the tape monitor switch is IN, no matter the position of the input selector knob. This is a line level input.

 

I hear the RECORDER input no matter what position the input selector knob is in, and this appears to be a line level input. Is this normal? What is the function of this input?

 

I hear nothing on the NAB TAPE and MIC positions, and find no correlating RCA inputs on the back of the unit. What are these inputs for?

 

Is the HEADPHONE an output on the back for headphones? These are two R and L RCA connections. There is also a 1/4-inch headphone jack on the front panel. 

 

Any assistance is much appreciated. 

 

 

 

 

 

Answers above in bold print

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Craig, excellent answer, that all makes sense and reconciles everything nicely. Thanks very much. 

 

BTW my model does in fact have a headphone jack on te front. Haven't tried it yet so i don't know if it cuts out the speakers or not. I

am not a headphone guy so I don't even have a pair with the 1/4-inch plug. 

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