Author Topic: Surfybear Spring Reverb Reverb Path Volume  (Read 177 times)

lars-musik

Surfybear Spring Reverb Reverb Path Volume
« on: March 01, 2023, 02:42:18 PM »
Hi folks,
I just finished a Surfybear Spring Reverb clone and am not really content with the volume/gain of the reverberation path. Thereís a huge volume drop when I turn the mix knob slightly up. Itís the third build on the same PCB/schematic but the first time this happens.

The JFETS are mmbf5457 measured according to specifications given in a former build documentation from the surfybear forum with a Peak Atlas DC75 (Vgs(off) <-1.2V; gfs >3,5 <5 mA/V).

Hereís the schematic with the voltages. Do you happen to find anything suspicious?

Thanks!





Kipper4

Re: Surfybear Spring Reverb Reverb Path Volume
« Reply #1 on: March 01, 2023, 03:16:40 PM »
Hey Lars.
What does it sound like at C8?
Might be a cap in the tone stack?
TC my friend.
Rich
"Duck_Arse
otherwise, you might end-up with SOIC or gullwings, for surface mounts."


Smoke me a Kipper. I'll be back for breakfast.

Grey Paper.
http://www.aronnelson.com/DIYFiles/up/

lars-musik

Re: Surfybear Spring Reverb Reverb Path Volume
« Reply #2 on: March 02, 2023, 06:01:57 AM »
Hey Rich,

I will check this out!

And I again realise how "impedance-thick" I am.  The original reverb tank has an imput impedance of 8 Ohm and an output-Z of 2250 Ohm. My new unit has 10 Ohm in,  2575 Ohm out. The off-precentage seemed to be absolutely OK to me. But could this make such a difference?

Kipper4

Re: Surfybear Spring Reverb Reverb Path Volume
« Reply #3 on: March 02, 2023, 12:50:44 PM »
Iíd have gone with the specs near enough.
Hope you find the issue.
"Duck_Arse
otherwise, you might end-up with SOIC or gullwings, for surface mounts."


Smoke me a Kipper. I'll be back for breakfast.

Grey Paper.
http://www.aronnelson.com/DIYFiles/up/