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Altec 353A input selector wiring

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I am helping a pal of mine with his partially gutted Altec 353A. The input selector switch was removed when he received it.
He just wants a simple line selector on there to select 6 inputs. I have a 6pdt rotary switch that would be great. He is using primarily phono, and line level sources. All interface with the RCA inputs on rear of unit.

Im having a heck of a time making sense of the original rotary selections for the Section 3 Rear Deck.

Without these localized feedback networks, the amp is unusable with regard to line noise.
Can anybody throw out some ideas for taming this beast.
Here are the 2 scenarios:

Phono source impedance.

Line level 1v type input.

I've tried to mock up (clip in) what I'm able to follow and the noise reduction is there, along with signal reduction too. But it's not right. My test source currently is my phone audio sent to RCA ins. The parts wired onto the RCA jacks themselves stand (phono) but that deck with the feedback elements are not present, and I'm seeing double from staring at em and trying to decode what switches in/shorts with the deck of the switch. I attached a link to the schematic and a zoom of the area in question. Any basic pointers would be great! Thanks.
https://2.bp.blogspot.com/-4Df_rARe8Xc/V_CnQszSX2I/AAAAAAABaAo/WtphxNDKofEVyTYcVlaDyigwHzWtgpdIgCLcB/s1600/altec%2Blancing%2Bpower%2Bamp%2Bvalve%2Btype.jpg
 

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Don't need to switch the RIAA eq parts, and don't need mic/ceramic/tape head inputs.
Probably don't need a tape out either. Just hard wire the RIAA parts (C6, C7, R11) and (C26, C27, R40)
on the pcb, to where the wires for the switch come from, and delete the tape out wiring.

Then wire the 5 line inputs, and RIAA stage outputs (from C9 and C29), to the new selector switch.
Grounds all remain the same, except delete any connections to the shorting sections of the old switch
(this is section 1-front and section 3-front).
 
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Rayma, thanks.

However, I'm totally confused on how to do this.

The original switch is not present.

Without the .047uf network off of the preamp sends to the power amp.
(.1uF/.047uF junction)
Where the feedback is introduced, it is in essence wired like a direct source to grid, like the mic input, I think????? For all my inputs. No network except the grid leak on v1 (47K).

It's got so much noise as soon as any source rca lines are terminated to the inputs, that you can't even listen, so I know that feedback network is the ticket. But I simply don't understand the circuit when it's switched in.

I hope I'm making sense. If i need to draw my simplified input topology, I'd be glad to do it. I'm at a loss, so I really appreciate the help.
 
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Was only the original switch removed, or was additional new wiring installed also?
That would confuse matters.

Line sources (other than phono) should work ok, have you tried a line source?
The phono stage will not work right if the switch was removed and nothing else done,
since the switch connected the RIAA components to the phono stage.
The switch did not alter the line stage, it just changed its input.

This schematic is kind of similar to what you want, where the op amp is the phono RIAA stage.
You may have to draw a schematic of what you now have.
 

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PRR

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You do NOT want the preamp (and NFB networks) for smartphone, CD, DAC, tape-deck, etc.

Take-out V1 V2.

Wire the MULTIPLEX RCA jacks *only* to the Standard/Reverse switch. Or if you know your left from your right, skip the switch and go to the BALance pot. Input sensitivity will be about 130mV full-up to 2V turned-down, covering all likely sources except a naked microphone, phono needle, or tape head.
 

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Thanks very much!!!
I figured I was ramming it!!!!

I’ll ponder over how the drive calculations were figured.

Now the RIAA for his phone input.
It’s a PTP assembled amp, so I’d like to stay away from active components being added.
Any links for a good RIAA network tag on for mag?
 
You first have to describe how many inputs you need.
Then, is one of those a magnetic phono cartridge . . . If so, retain V1 and V2.

To retain V1 and V2, hard wire the RIAA equalization.

Then add a new switch that selects the output of the phono preamp, the other line level inputs, and the output of the switch is connected to the top of the balance pots.

Of course, you may desire to have all the options that the original amplifier had:
channel reversal switch
mono - stereo switch
loudness contour
tape equalization
etc.
In that case, it needs the original switch and all the rest.
(Most modern stereo systems and modern signal sources, and modern recordings do not need any of that).
 
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I wired as proposed.
Hooked up my pioneer table. Seems to be attenuating the phono preamp signal quite a bit. Without the feedback it shrieks.

All other line selections are doing good.
Neat Max phone volume in sounds good but I really gotta crank the altec to get loud listening level.

I’m thinking this thing is 30w a side or so.
Sound about right to you.
Using some crappy pioneer towers from the 80’s impedance matched.

Thanks for the help. Any thoughts?
 
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