Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jonathan_kea on August 07, 2020, 11:06:35 am

Title: Stromberg-Carlson Phono Amp to Line Level?
Post by: jonathan_kea on August 07, 2020, 11:06:35 am

Picked up a Stromberg-Carlson New World AF-102 tube record player cabinet yesterday. The record player is shot, but the amp still works. Plugged an old iPhone into the phono input, and was able to get a low volume signal through.

I suspect that the reason for the low volume has to do with the input circuitry, designed to provide RIAA EQ to the phono signal (maybe?). Any recommendations on how to turn this input into a line level input?

Title: Re: Stromberg-Carlson Phono Amp to Line Level?
Post by: PRR on August 07, 2020, 11:16:01 am

> to provide RIAA EQ

No. It is a crystal needle and the EQ was built into the cartridge.

Title: Re: Stromberg-Carlson Phono Amp to Line Level?
Post by: jonathan_kea on August 07, 2020, 11:31:27 am

Got it - Do you see any components in the input section that would lead to low volume from an mp3 player cranked?

Title: Re: Stromberg-Carlson Phono Amp to Line Level?
Post by: shooter on August 07, 2020, 03:20:32 pm

Do you see any components

start with vdc checks and see how close they match the schematic

Title: Re: Stromberg-Carlson Phono Amp to Line Level?
Post by: jonathan_kea on August 07, 2020, 04:36:31 pm

Will do - it’s semi-attached to its console at the moment, making it difficult to open up. Have some rca extension cords coming tomorrow that will make it easier to pull out and have a speaker load.

I will say that after an hour or so of fiddling with the knobs it has come alive, much louder and the turntable is moving too. I’m thinking it might just need some deoxit in the controls then check voltages as you mentioned.