# Radium Springs (4 knob) white noise issue



## Iago (Mar 17, 2019)

I got what I think is the last of those PCB's and it took me a while to build it. Love the tone but the background white noise is a bit too much.

Details:
I'm using a 1 Spot power supply. I cannot, at the moment, try another PS.
The noise is there even if the Radium Springs is isolated in the signal chain.
The noise is there no matter how the Mix control is set, except it decreases a bit when I'm close to 100% wet.
It's too noisy to me even before reaching unity volume with the amp.
No mods where done to the circuit but using a 100K Log pot for Mix and 100K B for volume (I prefer the feel).


The only way I found to kind of counter the problem is to set the level of the Radium Springs really really low - to the point  its low even for bedroom playing - and then boost the signal back up with the volume of an overdrive pedal placed before it - so I get the desired volume increase but no white noise (the white noise doesn't increase using this method, only the reverb effect. Now, boost AFTER the reverb makes the white noise creep back in). However, doing that is very impractical in the real world - it means I must have an OD or boost always on and if I turn the reverb off, the pedal will make everything super loud.

Are there any mods I can do to help counter the white noise? I really don't want to part with this pedal! 
(pdf file of the build document goes attached).


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## Robert (Mar 17, 2019)

Remove R9 and install a jumper across R10 and see if that is acceptable to you.   This is going to lower the output volume considerably but will cut back on some of the hiss.


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## Iago (Mar 17, 2019)

Robert said:


> Remove R9 and install a jumper across R10 and see if that is acceptable to you.   This is going to lower the output volume considerably but will cut back on some of the hiss.



Hello! You mean I remove R9 _*and *_R10 and install a jumper in R10's place or should I leave R10 in?


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## zgrav (Mar 18, 2019)

I think the suggestion was stated correctly -- jumper r10 and remove r9.  Check the diagram in the build document and you can see that removing r9 takes out any amplification through the last op amp while the circuit still has a feedback loop through the capacitor c13.

Also go ahead and touch up your solder joints at the 100uf and two 47uf caps.  A bad connection on the electro caps can put a lot of noise in your signal path.


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## Iago (Mar 18, 2019)

zgrav said:


> I think the suggestion was stated correctly -- jumper r10 and remove r9.  Check the diagram in the build document and you can see that removing r9 takes out any amplification through the last op amp while the circuit still has a feedback loop through the capacitor c13.
> 
> Also go ahead and touch up your solder joints at the 100uf and two 47uf caps.  A bad connection on the electro caps can put a lot of noise in your signal path.



Ok guys, I did that (removed R9 entirely, left R10 in and soldered a jumper across it). It decreased the final volume (turning it up to 100% is now shy of unity volume) still, the noise is the same, the only difference is the amount of output volume I'm getting. 

I was thinking about trying a different approach. Since boosting the reverb gives me great results (while keeping the volume knob on the Radium Springs on very low settings, around 9 o'clock or so) I think that driving the input of the reverb harder would give me, possibly, better results. Are there any components I could change in order to drive the input of the pedal for more volume (without having to add a separate boost circuit)? 

Zgrav, I'll make sure to hit those caps with the soldering iron again.


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## Robert (Mar 19, 2019)

You can modify the input stage for some gain but you'll have to cut a couple traces and tack on two resistors.   

You can only go so far though before the FV-1 begins to clip.


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## Iago (Mar 19, 2019)

Robert said:


> You can modify the input stage for some gain but you'll have to cut a couple traces and tack on two resistors.
> 
> You can only go so far though before the FV-1 begins to clip.



I guess I'm keeping the pedal as is (without R9 and jumpered R10) - I think I was being a bit unfair and took my time to compare the hiss a little better (without staying too close to the amp is a good idea) and I'm more satisfied with the noise level now. I cannot point how quieter it is now... (30-50%?) but it definitely is quieter. 

I don't really want to risk damaging the PCB, but, out of curiosity, how could I increase the gain at the input? I think it will envolve breaking the connection between IC pins 1 and 2 and using a resistor there? What else?


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## Iago (Apr 17, 2019)

Solved in the following way: 

I built a mini SHO on a veroboard (10x5) with a gain trimpot and tucked that in front of the Radium Springs. I turned the volume down to 9:00 where couldn't hear the white noise, and turned the gain on the boost up until I reached unity. 

Then I removed the 10K resistor (R9) and made the feedback loop resistor (R10) 10K instead of 22K (not really necessary, I just wanted to get unity volume closer to noon on the knob). 

Can't hear white noise anymore, just good old 60 cycle hum. Unity volume is now 10:30-11:00 on the vol knob.  

(I also tried increasing gain at the front end of the opamp but I got the FV-1 into clipping very quickly... for this reason, I went with a boost I could fit inside the 1590B enclosure). Cheers everyone.


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