Cort GB Shortscale Preamp Question

[TeeSee]

I have taken stock of a lovely little shorty, the Cort GB active only short scale.
I already knew it was active only by reading reviews about it but I figured that at the price of the guitar new, I could switch out the pre with the likes of the Glockenklang I had installed into another of my basses which had the pull/push volume for P/A.
Unfortunately since it is only a single pickup guitar I could not use the glokenklang as that pre also has a blend pot, something I don't require.

Plan B would be to stick with the existing pre-and fit a new mini switch to switch A/P. The existing Pre is reported to be the Markbass MB-1 grabbed here from Corts site

When searching for the MB-1 however it looks like a completely different animal to whats in my guitar

this seems to have 5 pots I assume a blend pot, and it has the barrel jack out whereas mine is the bog standard jack out - obviously as it's an always on pre.

The question is, were I to fit an A/P switch how would the bass/mid/treble boost work in my configuration in active, would the passive circuit just bypass these, they would not act as tone circuits as there are no caps as such? The Glockenklang allows the boosts to be used in passive mode as tone controls but that is a much more complex animal to the "MB-1"

User @mikecd1 helpfully posted in another thread a diagram which they think is the way to fit a A/P switch. does this look about right to the guru's on here? Bear in mind they are talking about a pull push volume pot instead of the dumb pot already in the Cort. Is the numbered box referring to the pot connections on a pull push volume? I'm really not any good with electrical stuff, but I can wire a passive with the best of you - even if I don't understand half of it

Added complexity is the phase switch, I'm nervous about that, where would that fit into the diagram?
I have 4 options I could use some advice on;
1. Leave as is - don't really want to
2. Wire in a mini switch to switch active/passive - going to be really hard at my skill level
3. Used a stacked pull/push to switch between A/P - as 2
4. Source a preamp with a PP vol or switch to take care of switching A/P - big caveat - control cavity will not take a barrel jack as jack out position will clash with treble boost. Pre-amp would need to be for a single pickup, no blend pot required just V, Bb Mb, Tb - does something like that exist and then how would I wire in the Series/Single/Parallel switch, I have absolutely no experience in that at all.

Any advice on 4 particularly on a recommended 3band pre would be gratefully appreciated as long as a standard (not barrel jack) out can be used - I'm scratching my head to figure this out as most pre's that switch between A/P need the barrel to send the jack lead in to switch over to active, and when out conserve the battery life to become inert.

Is there an easy way?, am I overthinking as I'm wet behind the ears? It's a strange guitar to be active only, but wondering what you would do in this situation.
Some photo's but quality is bad as difficult to hold phone and take picture, I will update later when I got an extra pairs of hands to hold the pre out of the way.

.

 

[mikecd1]

In pursuit of an active / passive switch I had a wiring help thread a couple months ago trying to figure out if the green wire input to preamp now goes to the bottom lug in the switch and the pickup input from pickup switch now goes to the input on the A/P switch above it (I'm okay so far) but in diagram the brown wire output of the preamp now goes to the the switch (bottom right lug) and the output of switch above goes to the tip on the output jack what happens on the volume control if you've disconnected those two wires? The middle lug and the right lug of the volume control now have nothing if you've moved those two wires to the A/P switch and I wonder how the active electronics work if the output of the preamp doesn't go to the volume control anymore. I just don't know if this would work and nobody really replied with an answer. Its also a fair assumption even if it does work that none of the tone controls would work when bypassed. A push-pull pot is probably the way to go and I may have some info on that wiring coming soon as it would close the loop on the volume control operation. If its as easy as the bartolini diagram where the yellow wire is the preamp input and the green is the output this might work. Just take the output of the pickup switch to the new push pull volume pot.

 

[mikecd1]

A push-pull pot is probably the way to go and I may have some info on that wiring coming soon as it would close the loop on the volume control operation. If its as easy as the bartolini diagram where the yellow wire is the preamp input and the green is the output this might work. Just take the output of the pickup switch to the new push pull volume pot.

The push / pull wiring on the switch part looks identical to the a/p switch wiring so I'm more inclined to try the push pull since it shows exactly what to do with the lug wires on the top of the pot plus you wouldn't have to drill an extra hole to accommodate an extra a/p switch but that pre-supposes that one is okay with the preamp which I am at the moment. It would be nice to have passive in case of battery failure, but try to keep an eye on the batteries.

 

[-Asdfgh-]

I have taken stock of a lovely little shorty, the Cort GB active only short scale.
I already knew it was active only by reading reviews about it but I figured that at the price of the guitar new, I could switch out the pre with the likes of the Glockenklang I had installed into another of my basses which had the pull/push volume for P/A.
Unfortunately since it is only a single pickup guitar I could not use the glokenklang as that pre also has a blend pot, something I don't require.

Plan B would be to stick with the existing pre-and fit a new mini switch to switch A/P. The existing Pre is reported to be the Markbass MB-1 grabbed here from Corts site
View attachment 7472672
When searching for the MB-1 however it looks like a completely different animal to whats in my guitar
View attachment 7472674
this seems to have 5 pots I assume a blend pot, and it has the barrel jack out whereas mine is the bog standard jack out - obviously as it's an always on pre.

The question is, were I to fit an A/P switch how would the bass/mid/treble boost work in my configuration in active, would the passive circuit just bypass these, they would not act as tone circuits as there are no caps as such? The Glockenklang allows the boosts to be used in passive mode as tone controls but that is a much more complex animal to the "MB-1"

User @mikecd1 helpfully posted in another thread a diagram which they think is the way to fit a A/P switch. does this look about right to the guru's on here? Bear in mind they are talking about a pull push volume pot instead of the dumb pot already in the Cort. Is the numbered box referring to the pot connections on a pull push volume? I'm really not any good with electrical stuff, but I can wire a passive with the best of you - even if I don't understand half of it
View attachment 7472688

Added complexity is the phase switch, I'm nervous about that, where would that fit into the diagram?
I have 4 options I could use some advice on;
1. Leave as is - don't really want to
2. Wire in a mini switch to switch active/passive - going to be really hard at my skill level
3. Used a stacked pull/push to switch between A/P - as 2
4. Source a preamp with a PP vol or switch to take care of switching A/P - big caveat - control cavity will not take a barrel jack as jack out position will clash with treble boost. Pre-amp would need to be for a single pickup, no blend pot required just V, Bb Mb, Tb - does something like that exist and then how would I wire in the Series/Single/Parallel switch, I have absolutely no experience in that at all.

Any advice on 4 particularly on a recommended 3band pre would be gratefully appreciated as long as a standard (not barrel jack) out can be used - I'm scratching my head to figure this out as most pre's that switch between A/P need the barrel to send the jack lead in to switch over to active, and when out conserve the battery life to become inert.

Is there an easy way?, am I overthinking as I'm wet behind the ears? It's a strange guitar to be active only, but wondering what you would do in this situation.
Some photo's but quality is bad as difficult to hold phone and take picture, I will update later when I got an extra pairs of hands to hold the pre out of the way.

.View attachment 7472699View attachment 7472700View attachment 7472701View attachment 7472702

If the PP doesn't have an attached board, and sometimes it's just for soldering convenience and no logic in it, then you could snip it out and solder in resistors and wires instead to effectively pan to the only connected pick up.

 

[crazycloud]

If the pan pot on the Glockenklang is before the preamp (most likely), then simply don't wire it in or remove it from circuit - it's not needed. Ask GK how to do it as they will actually know the details of their circuit.

 

[TeeSee]

If the pan pot on the Glockenklang is before the preamp (most likely), then simply don't wire it in or remove it from circuit - it's not needed. Ask GK how to do it as they will actually know the details of their circuit.

Well I have this week off work, which will give me some time to open up the back of GK guitar and inspect pan pot. Thanks, I'll get back on this

 

[TeeSee]

If the pan pot on the Glockenklang is before the preamp (most likely), then simply don't wire it in or remove it from circuit - it's not needed. Ask GK how to do it as they will actually know the details of their circuit.

OK I've took the cover off the GK guitar and I notice that the pan (blend) only has 2 wires (other than the pickups wires) picture here as brown and black which only feed into the Vol Push/pull circuit board, (can also see the wires far right on the BL closer to the L I wrote) by the charred remains of my less than perfect soldering ) does it look like I'd be able to snip the blend out safely without affecting the rest of the pre? - not gonna do it on this guitar but if I bought a new GK I'd simply only wire the blend pot out- not fit it.

Also on the instructions the BL obviously takes the pickup, where would I connect the pickup signals to on the GK in schematic, bearing in mind we have the series/split/parallel.
Either way - getting the GK would only be a partial fit as the boosts do not act as tones in passive, either I presume on the MB or the GK other than that, on the GK sounds spot on if boosts are flat when either in A or P. - dunno if this applies to the MB
I can see why Cort decided to make it all active, for economy and also you always have control of your tone. I'm maybe wondering if this is a bridge too far for me, I would like to have the option to switch to passive though and I think it's a missed opportunity for Cort to allay the fears of folks who do lots of gigging. Either that or a battery health LED inbuilt into the guitar somewhere, doesn't have to be fancy just single RAG would be great.
I love the idea of swapping volume out with a pull/push but as @mikecd1 has said above it's yet unproven on the MB pre. If it gets done by someone far clever than me, I'll wait with bated breath. You may here me on here in the meantime asking the question on how to fit a simple battery health LED

 

[-Asdfgh-]

If the pan pot on the Glockenklang is before the preamp (most likely), then simply don't wire it in or remove it from circuit - it's not needed. Ask GK how to do it as they will actually know the details of their circuit.

On some preamps they are connected to little daughter boards to which the connections are soldered. I just checked on the Glockenlang (this would have saved me tracing the one I have if I'd looked before) and you are right - if you connect the pickup to pin 3 and 4 of the daughterboard for the volume, all should be good.

 

[-Asdfgh-]

On some preamps they are connected to little daughter boards to which the connections are soldered. I just checked on the Glockenlang (this would have saved me tracing the one I have if I'd looked before) and you are right - if you connect the pickup to pin 3 and 4 of the daughterboard for the volume, all should be good.

Pin 3 and 4 is counting from the bottom.

I still had to do some tracing as the pot broke so I have to work out how to replace it as trying to file the pins of a new one and drill out the board, etc didn't work. Or I've killed the preamp entirely.

 

[blizzard]

In pursuit of an active / passive switch I had a wiring help thread a couple months ago trying to figure out if the green wire input to preamp now goes to the bottom lug in the switch and the pickup input from pickup switch now goes to the input on the A/P switch above it (I'm okay so far) but in diagram the brown wire output of the preamp now goes to the the switch (bottom right lug) and the output of switch above goes to the tip on the output jack what happens on the volume control if you've disconnected those two wires? The middle lug and the right lug of the volume control now have nothing if you've moved those two wires to the A/P switch and I wonder how the active electronics work if the output of the preamp doesn't go to the volume control anymore. I just don't know if this would work and nobody really replied with an answer. Its also a fair assumption even if it does work that none of the tone controls would work when bypassed. A push-pull pot is probably the way to go and I may have some info on that wiring coming soon as it would close the loop on the volume control operation. If its as easy as the bartolini diagram where the yellow wire is the preamp input and the green is the output this might work. Just take the output of the pickup switch to the new push pull volume pot.

View attachment 7472757View attachment 7472763View attachment 7472822

The Bart wiring should work. You should solder the green input on the Cort in place of the yellow wire in the Bart diagram. Un solder the Cort orange wire to the volume lug and wire it to the switch in place of the green wire in the Bart diagram. This could be done on a separate switch.

 

[mikecd1]

The Bart wiring should work. You should solder the green input on the Cort in place of the yellow wire in the Bart diagram. Un solder the Cort orange wire to the volume lug and wire it to the switch in place of the green wire in the Bart diagram. This could be done on a separate switch.

Yes, the green wire in lower left in my pic is the green wire to the input of cort preamp instead of yellow wire in Bart diagram. The orange wire bottom right is wired to where the green wire was in Bart diagram and is the output to the preamp (green wire above it is the output of the pickup switch). The green wire on top to lug 3 in pic is wired back into the switch above the orange wire (as in Bart diagram and not sure what this does) the white wire on middle lug at top goes to tip and the black wire on left to sleeve. Checked it several times and all I got was hum.

 

[blizzard]

Pretty sure it's a bad ground, the black wire to the jack sleeve needs to also ground to the back of the volume pot as well as the grounds from the other pots and preamp. Notice in the Cort diagram, there is a bundle of wires from the pre to back of the volume pot and wires from the back of other pots. Also in TeeSee's gut shots there is a plain jumper from the third lug of the volume pot to the rear of the pot.