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)