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Surfy Bear / buffers

Started by 29palms, May 07, 2015, 04:24:04 PM

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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


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

Quote from: 29palms on May 07, 2015, 08:09:55 PM
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

Quote from: MacHeath on May 07, 2015, 09:04:40 PM
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


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?