Effects loop for SV20ish amp

[audiosalvage]

Hello. I have a newly built 1987 plexi circuit which is cathode biased. I'm very pleased with the sound, but I'd really love to add my reverb and delay pedals. Using them in front sounds terrible. I'm currently using an attenuator and experimented with running the LINE out into the reverb and then into a second amp. Sounds okay with reverb but the delay sound like crap. I dug into the secret sv20 schematic and am attempting to replicate their FX loop section. It does however require a 9v source, how do I get that from my amp? I have the 275-0-275 PT with 6.3v heater taps.
Does anyone have ideas or suggestions?

[Latole]

https://www.eleccircuit.com/9v-power-supply-circuit/

[Latole]

Or bough for $2 (?) a complete P.S in second hand store and put it in you amp

[pdf64]

Maybe the line out you’re using is crap or unsuitable, eg intended for +4dB when -10dB is required, or the wet amp is crap / unsuitable / set up inappropriately, eg getting overdriven somehow?
Or the effects can’t be set for 100% wet, 0% dry?

[tubeswell]

sv20 schematic and am attempting to replicate their FX loop section. It does however require a 9v source, how do I get that from my amp?

Latole's idea could get you close enough to get the relay to work - depending on how well the reservoir cap holds up and how much current the relay you're using draws. If you find Vout isn't good enough in the real world, try a voltage doubler in series with primitive shunt regulator (in the form of a lowish-resistance limiting resistor with a 9V zener to clamp Vout to 9V)

[audiosalvage]

I built the definitive lnd150 loops and ended up with blaring noise even with volumes off.  I then tried the 2 jack passive approach will great success, but only works with my reverb and delay pedals.  Chorus and flanger sound horrible and go in the front door with this setup