Surfy Bear / buffers

[29palms]

Hi all,
just built a Surfy Bear FET Reverb and have a question.

I built this to replace my Hardwire RV-7 (fantastic pedal BTW). I plugged the Surfy Bear  in before my Cardinal trem, where the RV-7 normally sits on my board and I got a very quiet reverb signal compared to dry even with the mix up full.

If I run the Surfy Bear into the RV-7 and then to the Cardinal it sounds great. Would I be right in thinking this is  a buffering thing?

thanks,
George

[rumbletone]

What tank are you using?

[29palms]

I'm using the 4AB3C1B tank by MOD as recommended by Bjorn who designed the circuit.

[MacHeath]

Well, judging by the schematic it seems the output impedance of the surfy bear is determined by the 250k mix pot, which can be quite high. I guess it could be a buffer problem then. If the input impedance of the Q1 transistor in your cardinal tremolo is too low it could be loading the surfy bear.

Do you have a boss or some other buffered bypass pedal you could try in between, to make sure?

[rumbletone]

I'm using the 4AB3C1B tank by MOD as recommended by Bjorn who designed the circuit.

Yeah that's the same tank I use and it is fine into the trems I've tried it with. Agree with the above suggestion to try something (buffer, etc.) between it and the cardinal trem to see if that makes a difference.

[29palms]

Do you have a boss or some other buffered bypass pedal you could try in between, to make sure?

Yeah the Hardwire is buffered bypass and the Surfy Bear works if I run it through that before the Cardinal, that's what made me think it might be a buffer thing. Sounds like you're in agreement?

[MacHeath]

Yup

[29palms]

thanks for the help guys, looks like I'll be adding a buffer to the Cardinal...
George

[midwayfair]

Huh. The input impedance if the cardinal is 2.2m -- which is higher than the other pedals. Can someone explain why a buffer is changing anything here?

[MacHeath]

Great that you chime in Jon, so is the input impedance of the cardinal determined by the pulldown resistor R1? I thought it would be Q1.

[29palms]

Sorry I'll try to clarify this.

I am running direct into a mixer rather than an amp, so I've always had a buffered pedal in the chain as a substitute for a DI box.

If I remove my Hardwire from the chain and replace with the Surfy Bear I will be losing the buffered bypass in the Hardwire and going to the Cardinal (last in the chain before the mixer) which I have wired for true bypass.

So if it's bypassed I wont be getting the 2.2M impedance and hence a low signal? Does that sound feasible or am I completely on the wrong track?