Fixing a Swedish Tube Amp

From a friend I got a badly mutilated high end preamp. Many items were missing: front panel knob, top/bottom/side cover, all RCA sockets, many resistors and diodes. Power transformer. Still, enough was still there, as a bonus even a lone ECC803S (original TFK!) so I decided to have a go at it.

The amp was designed by Lars and Anders Annerstedt from Stockholm, Sweden. Unfortunately no information about the preamp could be found except on a Japanese site. So I needed to investigate myself.

I quickly drew the schematic. Because some resistors were gone I simulated the amp in LTSpice using Norman Koren Spice models. If my assumption is correct and the amp should use ECC83 for the phono preamp and ECC82s for the post amp it solves nicely. However, the filament circuit had been modded suggesting ECC88. Only this is a VHF tube and ECC82/3 are intended or audio. I will have to do actual measurements to determine what tube to use. Maybe even the Russian 6Н1П-ЕВ, touted as an ECC88 replacement but radically different.

Next steps: I hope to get the power transformer. For testing I can use an external power supply. The solid state circuitry is functional, the missing parts easily ordered or liberated from my junk box.

To be continued!


symphonie_fp1

symphonie_fp2

symphonie_type_plate

symphonie_overview1

symphonie_overview2

symphonie_overview3

symphonie_overview4

symphonie_removed_rca

symphonie_sel_vol

symphonie_v(f)_timer

symphonie_bux

symphonie_fil_mod

symphonie_hv_psu

symphonie_led1

symphonie_led2

symphonie_phono_load

symphonie_sch_amp

symphonie_sch_psu

symphonie_sch_timer

symphonie_sch_v(f)

symphonie_sch_v(post)

symphonie_sch_v(pre)


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