I know Dumble always used relay switching, but was wondering if anyone has built using vactrol (optical) switching instead in a Dumble-inspired circuit?
I have a bag of vactrols and it would simplify some issues with space on my home-brew scratch build.
Optical (vactrol) vs. relay switching?
Moderators: pompeiisneaks, Colossal
Re: Optical (vactrol) vs. relay switching?
Can't say for sure, but I have spent many, many, (too many? 
) hours reading through threads on the Dumble forums and cannot recall anyone doing this. Not saying it hasn't been done or tried-just that I don't recall any threads about it.
It's an interesting idea, I wonder if it would color the tone any being Solid State?
) hours reading through threads on the Dumble forums and cannot recall anyone doing this. Not saying it hasn't been done or tried-just that I don't recall any threads about it.It's an interesting idea, I wonder if it would color the tone any being Solid State?
Glenn
I solder better than I play.
I solder better than I play.
Re: Optical (vactrol) vs. relay switching?
Mesa uses optical relays. I notice a lag when using, unlike mechanical relays. FWIW.
I build and repair tube amps. https://www.monkeymatic.com
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Richard1001
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Re: Optical (vactrol) vs. relay switching?
I used two vactrols in my C' lator to create a volume boost for soloing that can be switched with a footpedal.
In this situation it works really well and the switching is silent. In my amps i have used relays but there is no reason why it should not work using vactrols. The Mesa MK3 uses kind of the same way to create overdrive as an ODS. The only downside is that vactrols can wear out over time.
https://ampgarage.com/forum/viewtopic.p ... 34#p449734
In this situation it works really well and the switching is silent. In my amps i have used relays but there is no reason why it should not work using vactrols. The Mesa MK3 uses kind of the same way to create overdrive as an ODS. The only downside is that vactrols can wear out over time.
https://ampgarage.com/forum/viewtopic.p ... 34#p449734
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dorrisant
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Re: Optical (vactrol) vs. relay switching?
Also, who knows how long Vactrols will be available? I have been a Mesa factory service tech for a long while and they are less and less available as time goes by... even from Mesa stock. Ymmv.
"Education is what you're left with after you have forgotten what you have learned" - Enzo
Re: Optical (vactrol) vs. relay switching?
I don’t think it would color the tone much. The side that handles the signal is just a light dependent resistor. The other side is just a red LED.
When dark, the LDR is >10-megohms. When lit, it is like 100 ohms. So it isn’t a hard switch like a relay. But they ramp up and down in a few fractions of a second. The on/off release rate depends on which vactrol you pick.
I have some, of the somewhat better than poo-quality China ones. Nothing like old ones made by Perkin-Elmer.
They have different on/off rates. Some are meant as switches, some are meant as variable resistors.
They just easy to tack on an eyelet board and LED on-off is easy to implement.
When dark, the LDR is >10-megohms. When lit, it is like 100 ohms. So it isn’t a hard switch like a relay. But they ramp up and down in a few fractions of a second. The on/off release rate depends on which vactrol you pick.
I have some, of the somewhat better than poo-quality China ones. Nothing like old ones made by Perkin-Elmer.
They have different on/off rates. Some are meant as switches, some are meant as variable resistors.
They just easy to tack on an eyelet board and LED on-off is easy to implement.