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  1. tschrama

    I can't decide what to do

    15..45 dollar soldering station, fix the cable ur self. Secondhand clothing store to pickup some comfy fabric to make you guitar strap comfy. By the wife and or childeren something good, safe for education or a rainy day. 3600 dollar on a gibson? Nfw
  2. tschrama

    Glen's Trainwreck.

    Yeh steel is harsh, alu is where the tone is. Lmao
  3. tschrama

    ~1985 broken in V30s or new Marshall V30s

    Eh. Depends on what you think sounds best…?
  4. tschrama

    Replacement speaker for DSL40CR, Creamback G12H or V30

    Yesterday I measured eight V30s … you wont believe the amount of difference between them. Between 6.5kHz and 8kHz, were they start to drop off dramatically, I measured differences of 21dB no less. So one V30 sound cool en creamy yet articulate, yhen another one sound very shrill. I hope you...
  5. tschrama

    JVM410H BIAS problem after modding and retubing - SOLVED :-)

    Good photo of ur solder job could help.
  6. tschrama

    JVM410H BIAS problem after modding and retubing - SOLVED :-)

    Double check the resistor values. Metalfilm resistor color codes can look different. So measure them.
  7. tschrama

    JVM410H BIAS problem after modding and retubing - SOLVED :-)

    That ‘ mod bible’ is useless disinformation.
  8. tschrama

    JVM410H BIAS problem after modding and retubing - SOLVED :-)

    Set bias to -55volt. And see what happens. Adjust bias supply resistors if nessecerry.
  9. tschrama

    Marshall Valvestate 8080 vs Marshall Valvestate 8100

    The 8080 and 8100 are actually the only two from that series that are the same. All other models have a slightly different preamp tuning.
  10. tschrama

    You're a skilled Technician with a Vintage Modern on the bench . What do you do ?

    schematic? What is your problem with the tone now? What direction do you what to get the tone to?
  11. tschrama

    Lead 12 effects loop?

    I dont see a line ouput, except a DI output from the power amp. Dont use that. But if you just take the signal from the wiper of the volume pot, and use that as FXsend, and use C8 as the FXreturn, it wil prolly work. Allbeit a bit low-fi and maybe with lowish output. But you wouldnt even need...
  12. tschrama

    Just finished this JTM50

    Beautifully build
  13. tschrama

    Filament "0" Volt Center Tap?

    You could be right, but the PT radiation is in sync with the current slike, that is twice the mains frequency. On top of that, I never had a amp build that suffered from 50Hz heater interference, wether I used marshall style heater wirkng or Soldano style wiring. But I have experinced rectifier...
  14. tschrama

    Filament "0" Volt Center Tap?

    I think the magnetic flux caused by the AC heater is low because it is only a single loop. While the power transformer has many windings. Furthermore, the HT AC wires contain high peak current, representing high frequencies, but the heater wires and low frequency without current peaks.
  15. tschrama

    Filament "0" Volt Center Tap?

    I had to re-think about it for a bit. I focussing magnectic/inductive coupling. That happens due to a large AC current through a loop causing an AC magnetic field. This happens in the power transformer and a bit around the AC wires from the power transformer. Such a AC mag field can couple into...
  16. tschrama

    Filament "0" Volt Center Tap?

    True, bit it might capture the stray ac magnetic field from the power transformer, not?
  17. tschrama


    1. Tr1 with Tr6 simulate an inductor. It’s a inductor based resonance circuit. 2. no idea. Might be just a bandlimmited gain stage to get the voltage swing up again after the FX level. Cannt see from the tiny schematic snippet. Please post complete schrmatics.
  18. tschrama

    Rest In Peace Howard Alexander Dumble

    sincerely hope he forgave himself for that electron lattice fragile harmonics episode. May he rest in peace and be forever proud of his accomplishments.
  19. tschrama

    NAD x2!! Jose Arrendondo modded 1971 Marshall Super Leads

    Hope you made shot gut shots before you send it away…….
  20. tschrama

    Overdrives ... If you had to pick Three (3)

    1) RAT 2) ts9 3) horse 4) ge7