# Photon Vibe Treble Loss?



## orangetones (Jan 14, 2022)

When comparing my Photon Vibe to my traditional Univibe build our even my Electrovibe, I find there is significant treble loss.  I find to have anything close to decent, the Treble or Hi knob has to be turned all the way up.  I'd actually like more treble in the signal.

What modifications would you guys suggest?  Is there anything in this circuit that would be causing that Treble Loss?


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## Big Monk (Jan 14, 2022)

orangetones said:


> When comparing my Photon Vibe to my traditional Univibe build our even my Electrovibe, I find there is significant treble loss.  I find to have anything close to decent, the Treble or Hi knob has to be turned all the way up.  I'd actually like more treble in the signal.
> 
> What modifications would you guys suggest?  Is there anything in this circuit that would be causing that Treble Loss?



I think you answered your own question.

Look to the schematic in the section where the Hi Cut knob is and tweak C18. Look at the Low Control as well.


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## orangetones (Jan 14, 2022)

Big Monk said:


> I think you answered your own question.
> 
> Look to the schematic in the section where the Hi Cut knob is and tweak C18. Look at the Low Control as well.



I am not very well versed in this stuff.  Question, when the Hi knob is turned all the way to the brightest setting (most Treble) does that cap actually do anything?  Won't changing it just affect the roll off when it is turned down?

Are you able to explain or point me to an explanation of how this Treble control works?

Also, how would the low control affect the treble cut I'm hearing?


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## Big Monk (Jan 14, 2022)

orangetones said:


> I am not very well versed in this stuff.  Question, when the Hi knob is turned all the way to the brightest setting (most Treble) does that cap actually do anything?  Won't changing it just affect the roll off when it is turned down?
> 
> Are you able to explain or point me to an explanation of how this Treble control works?
> 
> Also, how would the low control affect the treble cut I'm hearing?



I’m not 100% familiar with the circuit but I imagine changing the value of the Hi control would have more affect on the treble content because as you said, the cap really affects the Hi cut. 

The Low control is an input cap blend so it sets the amount of lows entering the circuit. Making the smaller cap smaller will shift down the minimum low setting.


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## music6000 (Jan 15, 2022)

Big Monk said:


> I’m not 100% familiar with the circuit but I imagine changing the value of the Hi control would have more affect on the treble content because as you said, the cap really affects the Hi cut.
> 
> The Low control is an input cap blend so it sets the amount of lows entering the circuit. Making the smaller cap smaller will shift down the minimum low setting.


Try 10nF @ C18 & see if that is more to your liking, it should be as *Big Monk* has suggested.


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## orangetones (Jan 15, 2022)

In can do that, but I have a question that no one seems to be answering.  When the Hi knob is turned all the way up, is that capacitor actually doing anything?  I thought this functioned to roll off the high end.  I was under the impression that when it is fully turned up, it is letting everything through on the high end and no ruling anything off. Or is it the case that when the Hi knob is turned all the way up (the brightest sound) that the capacitor C18 is still affecting the circuit.


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## music6000 (Jan 15, 2022)

It is still in the Circuit & is going to Ground so by lowering it to a lower value means a lesser value is going to give you more Treble overall!


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## orangetones (Jan 15, 2022)

Sounds good.  I'm guessing I could just eliminate that altogether if I didn't want the functionality.


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## music6000 (Jan 15, 2022)

orangetones said:


> Sounds good.  I'm guessing I could just eliminate that altogether if I didn't want the functionality.


It will still benefit from having a Cap there as it may become a redundant knob without it!


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## Big Monk (Jan 15, 2022)

Keep in mind that the Low Knob is a simple cap blend as well and changing the lower valued cap (2.2 nf) will shift the lower threshold of the Knob down (higher frequencies let through at lowest setting but not much since 0.0022 uf is already pretty small).

How are you setting the Low control @orangetones?

EDIT: @music6000 pointed out my error in identifying the lower Low cap value. I fixed my recommendation above.


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## orangetones (Jan 16, 2022)

Big Monk said:


> Keep in mind that the Low Knob is a simple cap blend as well and changing the lower valued cap (2.2 nf) will shift the lower threshold of the Knob down (higher frequencies let through at lowest setting but not much since 0.0022 uf is already pretty small).
> 
> How are you setting the Low control @orangetones?
> 
> EDIT: @music6000 pointed out my error in identifying the lower Low cap value. I fixed my recommendation above.



Often setting the low knob around half way I would guess.


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## Big Monk (Jan 16, 2022)

orangetones said:


> Often setting the low knob around half way I would guess.



Try lowering it.


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## thesmokingman (Jan 19, 2022)

why they chose a low-pass filter for a high control is decidedly lovepedal ...


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