# Muroidea no sound.



## Travis (Dec 11, 2020)

I built a Muroidea, try with some ICs and with some 2n5458... It's doesnt sound.

Some help please?

Thanks


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## Nostradoomus (Dec 11, 2020)

Which ICs have you tried? 4558 is a dual opamp and this build calls for a single. LM308 is the standard but people have had good results with TL071, OP07 etc.


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## Travis (Dec 11, 2020)

Ok I Will buy some LM308 and try. Thanks


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## Travis (Dec 11, 2020)

Now I remember first time I turn It on was with a LM308N and It doesnt sound too


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## Nostradoomus (Dec 11, 2020)

Where did you get the lm308 and 2n5458 from?


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## Travis (Dec 11, 2020)

Tayda


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## BuddytheReow (Dec 11, 2020)

Does bypass work? Also did you make sure your amp an guitar are plugged in to the right jacks?


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## Travis (Dec 12, 2020)

Yes bypass works and I use the right jacks


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## Travis (Dec 12, 2020)

I try with a LM833N from Tayda and it's doesnt sound


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## Untro (Dec 12, 2020)

Well ive always used either an op07 op amp or a TL71, both from tayda. The LM833 seems to be a dual op amp again, so make sure to check to see if you have any single channel op amps.


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## Travis (Dec 15, 2020)

I replace with TL071 and new 2N5458 and nos it's sound but It makes Huge whistle when I turn gain more than 60%


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## Nostradoomus (Dec 15, 2020)

With a TL071, snip out the 30pf cap from pins 1-8. I have had to add small buffer circuits to the front end of rats after running in to the same issues. Does turning the filter knob change the frequency of the oscillation?


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## Travis (Dec 15, 2020)

Nostradoomus said:


> With a TL071, snip out the 30pf cap from pins 1-8. I have had to add small buffer circuits to the front end of rats after running in to the same issues. Does turning the filter knob change the frequency of the oscillation?


Just the oscillation come Down when I turn gain less than 60-50%...
So I must remove 30pf?


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## Travis (Dec 16, 2020)

I try to remove the 30pf and the whistle stay there


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## Travis (Dec 16, 2020)

I replace Gain with 50K pot and now its everything ok


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## Tanner30 (Mar 10, 2021)

hi all, I just built this same pedal and I'm having the whistle oscillation sound as well. I am using a TL071. I was troubleshooting and referenced the data sheets. I noticed the TL071 has a different pinout than the LM308. Pin 8 on the TL071 is not connected. the pin 5 on the LM308 is not connected. Initially i was not getting audio to pass until I used a jumper to get from the 30p cap to pin 5, connecting pin 1 to pin 5) and clipped pin 8 on the IC. I now have sound but I'm experiencing the same issue of the loud whistle. I tried removing the 30p cap and it doesn't change the whistle. I also replaced the A100k pot on the filter with an A25k (didnt have A50k on hand) and there is no change in the whistle. 

I checked each component during install to make sure the values were correct. I have also checked the caps, diodes, IC and the JFET for proper orientation.  

Any ideas what could be causing this?


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