Hi!
I have tapped all my electronics guru resources and understood that what I thought was a simple matter is not so straight-forward.
Essentially, I want to create an electronic "switch" that can be used to connect two electronic guitar pickup signals: first signal alone, second signal alone, both in parallel, both in series and both in parallel out of phase.
One of these could be used to control a single humbucker. Two could be used to control a three pickup single-coil instrument, etc.
To simplify matters, creating something that is an electronic version of a DPDT switch would suffice. I believe that things like impedances etc of guitar pickups make it more complicated?
Any input would be greatly appreciated. For details on my current project, please see my home page.
Thanks in advance,
Ola
I have tapped all my electronics guru resources and understood that what I thought was a simple matter is not so straight-forward.
Essentially, I want to create an electronic "switch" that can be used to connect two electronic guitar pickup signals: first signal alone, second signal alone, both in parallel, both in series and both in parallel out of phase.
One of these could be used to control a single humbucker. Two could be used to control a three pickup single-coil instrument, etc.
To simplify matters, creating something that is an electronic version of a DPDT switch would suffice. I believe that things like impedances etc of guitar pickups make it more complicated?
Any input would be greatly appreciated. For details on my current project, please see my home page.
Thanks in advance,
Ola
4 switches. Forget the impedance.
1. 1
2. 2
3. 1&2
4. 1&3
5. 4
w
There might be a smart way to do this with less switches, but I can't see it at the moment...
An externally hosted image should be here but it was not working when we last tested it.
1. 1
2. 2
3. 1&2
4. 1&3
5. 4
w
There might be a smart way to do this with less switches, but I can't see it at the moment...
ola_strandberg said:
Yes, there is a challenge in creating these, not directly because of the impedance, but the fact that passive pickups' are very low level signals. I don't know this field of electronics well, but I think that will find that solid state relay technologies will all have much too high leakage current to work in this app. I think your best option would be to read some of the forum threads on relay based attenuators. Relays optimized for small signals like used in those apps are likely your best bet.
Re: Re: Electronic guitar pickup selector
Guitar pickups put out healthy level. In fact some high OP humbuckers
can put out over 1V for a short period of string attack.
The issue is very much the high impedance. The gtr pickup wants
to see very high Z and very low C and hopefully no solid state type
capacitive modulation.
T
leadbelly said:
Guitar pickups put out healthy level. In fact some high OP humbuckers
can put out over 1V for a short period of string attack.
The issue is very much the high impedance. The gtr pickup wants
to see very high Z and very low C and hopefully no solid state type
capacitive modulation.
T
BS. This is music, not electronics. If you start ******** around with active devices you'll need a battery in your guitar.
Later production Fender Strats have a simple switch arrangement to allow adjacent pickups to be connected in parallel. There is no impedance issue.
Just connect up the switches as shown above and try it...
w
Later production Fender Strats have a simple switch arrangement to allow adjacent pickups to be connected in parallel. There is no impedance issue.
Just connect up the switches as shown above and try it...
w
Please have a look at the switches offered at StewartMcDonald (www.stewmac.com). In general, if it's not there it's not worthwhile.
wakibaki said:
I have -built- from ground up, including neck and frets, 3 electric
guitars, hand wound quite a few pickups, high and low impedance.
Designed and built discrete on board active electronics for gtrs.
Designed and built tube and SS recording equipment, amplifiers, mic pre
amps, d-a converters.
cheers
Terry
Re: Re: Re: Re: Re: Re: Electronic guitar pickup selector
I haven't posted in this part of the forum and don't know the tech
level here.
Apologies for any misunderstanding, explanation follows:
Gtr pickups are V high impedance & are sensitive to load they are
driving. Hence the sound change when you plug a longer cord in.
The poster suggested possible use of SS switching.
Capacitive load of an active device used for switching can change
capacitance with voltage swing, not ideal for gtr pickup.
My point; look at the load it is putting on the gtr pickup.
WRT relays, agreed, minimal sonic impact on the pickup.
WRT contact arrangement, wakibaki your schematic looks good.
cheers
Terry
PS, you can make an active pre amp for high impedance pickups
that doesn't change the sound, but that's another thread.
wakibaki said:
Nigel Goodwin said:
Perhaps you would care to expalin it then?
It's just a load of meaningless rubbish.
I haven't posted in this part of the forum and don't know the tech
level here.
Apologies for any misunderstanding, explanation follows:
Gtr pickups are V high impedance & are sensitive to load they are
driving. Hence the sound change when you plug a longer cord in.
The poster suggested possible use of SS switching.
Capacitive load of an active device used for switching can change
capacitance with voltage swing, not ideal for gtr pickup.
My point; look at the load it is putting on the gtr pickup.
WRT relays, agreed, minimal sonic impact on the pickup.
WRT contact arrangement, wakibaki your schematic looks good.
cheers
Terry
PS, you can make an active pre amp for high impedance pickups
that doesn't change the sound, but that's another thread.
Re: Re: Re: Re: Re: Re: Re: Electronic guitar pickup selector
Hi Terry,
I think we all understand the requirements for a guitar pickup, but what we're all baffled by is your "capacitance change" - anything you're going to connect to a pickup, that will meet it's loading requirements, won't exhibit any such effect.
As with any such switching problem, the best solution is mechanical contacts (either switches or relays), any electronic solution is merely trying to emulate such a circuit, and making a poorer job of it.
Terry Demol said:
Hi Terry,
I think we all understand the requirements for a guitar pickup, but what we're all baffled by is your "capacitance change" - anything you're going to connect to a pickup, that will meet it's loading requirements, won't exhibit any such effect.
As with any such switching problem, the best solution is mechanical contacts (either switches or relays), any electronic solution is merely trying to emulate such a circuit, and making a poorer job of it.
Re: Re: Re: Re: Re: Re: Re: Re: Electronic guitar pickup selector
http://pdf1.alldatasheet.com/datasheet-pdf/view/30581/TOSHIBA/2SK170.html
Check Crss and Ciss, page 3. With the usual supplies, it's not a
problem, however with onboard electronics running off a 9V battery,
PS = +-4V or so. This is right at knee of C versus voltage
change. So it depends on the type of semis used and the
configuration, but the low PS rails can make it an issue.
It's just one of the reasons gtr sounds great plugged straight into
tube amp. Tube = a couple of pF / zero modulation.
cheers
Terry
Nigel Goodwin said:
http://pdf1.alldatasheet.com/datasheet-pdf/view/30581/TOSHIBA/2SK170.html
Check Crss and Ciss, page 3. With the usual supplies, it's not a
problem, however with onboard electronics running off a 9V battery,
PS = +-4V or so. This is right at knee of C versus voltage
change. So it depends on the type of semis used and the
configuration, but the low PS rails can make it an issue.
It's just one of the reasons gtr sounds great plugged straight into
tube amp. Tube = a couple of pF / zero modulation.
cheers
Terry
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