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I have a question to add. Would the circuit you're recommending work coming off the plates of V1 to switch the 'Volume' pots pre coupling cap in a 5F6a circuit? I don't see why not but just want to confirm...
Cheers
C_S
Cheers
C_S
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No. You always need to have a coupling cap before going to any pot. High voltage from the plate going to something you will touch with your hand? You do the math....
This would work fine afterthe coupling cap and before the grid.Comment
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Cheers for the reply. Lack of description on my part. The cap would come before the pot, but the relay will come before the cap. I suppose it would be better to put the relay after the cap though eh?
C_SComment
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Chris
Good proposal to use the compromise. I added a schematic like I would assemble it.
Do you think there would another pair of 1M resistors around relay1A be necessary to calm the pop?
And what value should the resistors R1 and R2 have? I believe they don't have to be that big (around 100 K?).
This is similar to the master volume section in the Peavey 5150 amp, except they don't switch the ground of the volume pots with a relay. I think there must be some influence in the range of either pot caused by the other pot in case they are not switched "out" of the schematic completely. Right?
MattAttached FilesComment
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Yeah. You want to avaoid switching DC if at all possible. It would be very noisy swithcing at best.Comment
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Chris
Thats right. I want to switch the ground, cause I use a footswitch too (stereo phone plug for channel and master volume switching) and I don't wanna send the DC over the footswitch. Ground feels better to me to be switched. Do you think it'll work the way I drew it?
C_S
Have you done that before, or are you looking for a way like this for the first time?
I think it would be best to have the complete switching section in between two caps (one cap from the preamp - switching relays and master volume controls - cap to the PI).
You might leave out the cap to the PI, cause I don't think it would do any harm. I used both kinda ways in two different amps and either works fine. Never leave out a cap before a pot... you know the rest. HV over the pot = no goodLast edited by txstrat; 03-19-2008, 10:25 PM.Comment
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It's OK to send low voltage DC down to the footswitch and use the footswitch to route the DC somewhere. That's no problem at all and it is down all the time.
I was referring to the Colonels question about putting the relays in the circuit between the plate & the coupling cap. Not a great idea.Comment
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I don't think so either, even over a good relay I wouldn't feel good to send the HV.
Do you think it would be less noisy to switch the DC instead of the ground? What about the current draw? I sometimes use a footswitch cable a long as about 20 feet.
Not that I'm used to the big stages all the time. But sometimes lay the cable around the drumset and other stuff ;-)Comment
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That would work but I was thinking something more like the attached sketch. I've never used the "attach" feature here so I hope it works.
Sorry for the hand sketch but it was the quickest way for me.Attached FilesComment
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It really shouldn't be a problem. Relays are very forgiving. A 12V relay usually has a minimum "on" voltage somewhere around 7-8 Volts.
I also have a very long footswitch cable (switching the LV DC) and a very low DC supply for my relays but even that works.Comment
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Well this is a fourth way to switch.
I believe this is it. As far as I'm concerned I think it will reduce the pop to a minimum and ALSO have the not used pot switched to ground.
Absolutely great. The hand sketch is pretty OK. Thank you.Comment
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I could use a different IC instead of the IC7812. Is there a IC 7814. I read in the manual of the relays they have max voltage of around 30 volts. 14 or 15 volts shouldn't be a problem. Is this really the less noisy way to switch?Comment
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Thanks Chris, legend.
TX, Its my first time using relays, and switching pots. I'll go after the coupling cap, but I'll leave the PI cap off for now.
Cheers,
C_SComment
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