Help Please!! - Hohner Jack upgrade to series wired pickups

[GrahamT]

Hi All,


I have a mint condition original, unmodded Jack headless which has active J type EMG select pickups. I have seen on the forum posts about an upgrade which puts the pickups in series (thanks to geoffbyrne for his advice on this), but I would prefer to utilise the existing holes, not drill another one for a switch or use the red LED hole - I quite like the light .

Whilst I am not a total space-cadet when it comes to electrics, I am a little lost with electronics so I would be very grateful if any if you who have knowledge in this area could help me. I know that there has to be a switch to select parallel or series which has been achieved by others using a push-pull, but is there one available which also incorporates the facility to blend the inputs from the pickups? Would it be possible to have one volume pot to serve both parallel and series modes and a blend-with-select switch? Maybe I could use a second concentric pot as is used for the treble/bass...?

As you can see I am somewhat confused.

This is the wiring diagram that I have cribbed from another Basschat post (thanks to Sean) :-


[color=#282828][font=helvetica, arial, sans-serif][/font][/color]

[color=#282828][font=helvetica, arial, sans-serif]All help gratefully received.[/font][/color]

[color=#282828][font=helvetica, arial, sans-serif]Ta,[/font][/color]
[color=#282828][font=helvetica, arial, sans-serif]Graham[/font][/color]

Edited October 9, 2013 by GrahamT

[GrahamT]

Bump..

[SparkBird]

I might be abvle to help you Graham but first ; As i remember the emgs in the Jack were passive but with an active circuit .Thats suggested in the diagram as well because there is no battery power to the pickups. The more common 'expensive' EMGs are just about the only active pickup opn the market , that is they have a preamp inside each pickup . An active tone bass or guitar is almost always a passive pickup with an active tone circuit , not the same thing .
Anyway if they are passive then the pots will probably be 250k or 500k , I'll guess 500k . I need to know that , have a look, it should be marked somewhere on the pots . Once i know that i'll tell you the available options that i know of .

[GrahamT]

Hi SparkBird,

Thanks for looking at this for me - I had all but given up hope of sorting this out!
I will have a look inside tomorrow and let you know.

ATB,
Graham

[brensabre79]

I think the EMGs must be passive looking at the above.

DO you like the volume for each pickup layout? I don't, so when I modded my Jazz I configured as follows:

Rotary 5 position PU switch: Neck - Neck+50%Bridge - Both - Bridge+50%Neck - Bridge (or you could have a blend knob)

Master Volume with S-1 switch in the top (push/push) to connect pickups in series and override switch (you could use a pull up vol pot instead).

Stacked active tone controls.

I can post diagram if that's of interest.

[GrahamT]

Thanks, Brensabre79, that is [u]exactly[/u] what I was looking for. Please post the diagram. Where did you source the pots? I have a Maplins nearby.

I have yet to find the time to have a look at the pots regarding their k rating.

Thanks for the help so far, guys.

[brensabre79]

OK Here's the diagram. I think it's right, it was a long time ago when I did this... (series parallel switch on the left may be mirror image depending on what default state you want) - BPU –ve should also go to earth!



You need the Fender S-1 pot. I got mine with a Jazz bass but you should be able to source one [url="http://www.allparts.com/006-1260-000-250K-Pot-Assembly-for-Tele-S-1-Switch_p_72.html"]online[/url].

Also a 2 pole 5 position rotary switch (should just fit in the place of second volume pot) - a bit fiddly to wire up. ([url="http://www.maplin.co.uk/rotary-switches-2417"]Maplin[/url] or [url="http://www.ebay.com/itm/1pc-Rotary-Switch-2-Pole-5-Position-for-G-ES345-5P-/300645910911"]eBay[/url])

This circuit also uses [url="http://www.maplin.co.uk/cermet-preset-potentiometers-2200"]mini-preset variable resistors[/url] (250k) to pre-set the blend level of the pickups (you can use a blend pot if you prefer - much simpler wiring, but slower to get 'that' sound on stage). (Maplin) - I'd set up the blend while the control panel is open, once you're happy, put it all away and you'll have that blend every time

Edited October 17, 2013 by brensabre79

[GrahamT]

I had a look inside and they are 500k pots. Does that mean that I should buy 500k resistors to match?

I have followed your link to Maplins for the resistors and if I am looking at the correct product, they are called Cermet preset potentiometers and do not have 250k, let alone 500k values. Am I on the wrong page?


Also, if I go the push/push S1 route, will I have to use a Fender knob? If so, to keep the bass looking authentic, I would prefer to use a pull up vol pot and the original knob.

Edited October 17, 2013 by GrahamT

[SparkBird]

Graham,
yeh i guessed they'd be 500k makes more sense . You don't need cermet .

To keep the knobs , you need to know the diametre of the hole the pot shaft goes into . Or pack them or drill if they turn out to be too small/big . But best get it right one , no ?
You need to know the length of the shaft , cos too short would be a proper bugger .
You need to know the diameter of the pot case to make sure theres space for whtever you buy . 16mm or 24mm normally .
Finally i'll send you a link for how to wire it up , its simple really. IF you have problem i can help .
Do you really want blend instead of two volumes (I'll have to think about that too tired right now) .,two vols is more versatlie anyway but.....
Anyway if you do , you need a dual 500k 'blend' pot . i'll get to where you can buy it all later , depending on what you want to do.
And a cheaper option than the fender S-1 ( i don't know off hand if they are available as 500k ) is the master vol push pull or easier still , at least for me , is a push on , push off ( not S1). i'll get to where you can buy it all later depending ....

Edited October 17, 2013 by SparkBird

[brensabre79]

[url="http://www.maplin.co.uk/sub-miniature-fully-enclosed-carbon-preset-potentiometers-6499"]Sorry, These[/url] should do if you go down that route.

But SparkBird is right, there is a much simpler way than S-1 and Presets.

If you're happy with a blend pot or even two volumes then that saves a LOT of hassle.

However you do it, the wiring for the Series/Parallel is really simple - and you can do this with a pull up volume pot.

[attachment=146406:ser-par-lp-N.gif]

[GrahamT]

Guys,

I think that a pull up vol pot and a blend pot should do it. I will take measurements of the existing pots and holes and try to match up with the offerings from Maplin etc. With this config, which wiring diagram should I use?

I am hugely grateful to you for spending your time helping me with this. I really love the Jack and enjoy playing it.

Graham

[brensabre79]

500k Volume pot with pull up should replace existing. You'll also need a 500k blend (Basically two 500k volume pots back to back).

You may have to translate the wiring diagram i put above for the series parallel for pull up vol pot (but the switch bit should be separate to the traditional volume pot connections anyway...) Below is how to wire up a Vol, blend, tone - it says Jazz bass but will work for any 2 pickup bass.

So you'll need to just substitute the pickup switch in the one above for the blend in the one below... (White is the Pickup +)

[GrahamT]

Okay, i'll order the parts and give it a go.

I will report back presently.

G

[SparkBird]

Bren , hang on , am i missing something ?
In the series/parallel diagram there is only one output , there are no vol pots or dual between the pickups and series switch .
So he could only have a series switch , master vol and no control over individual pickup volumes .

In the jazz diagram he can blend pickups but , if he has the series switch before the dual ... well he can't blend as there is only one output from the series switch to the blend and he can't put series after blend because theres only one output from the blend .

I think he's maybe obliged to have two volumes between picks and series switch isn't he ? and i'm not even sure he can do that .

No .... Its been a long day i'm tired ,maybe i'm missing something obvious , but i've no time tonight, i can't force my poor head round this instantly, i have to eat and go play so ... what do you think ?

Edited October 18, 2013 by SparkBird

[brensabre79]

I think the blend control works just like a pickup selector switch (2 inputs one output) it's just you have more control - however, I've not tried this because I really don't like blend controls (for the simple reason that on a gig, where you have to get the right sound quickly, and usually without auditioning it, switches are more reliable).

For the OP, the series / parallel switch above should knock out the blend control (i.e. it will be useless) - I think Fender do this slightly differently though because, their way (with 2 vol controls) it's possible to turn the bass off if you flick the switch while the bridge vol. is full and neck vol. is off - which is a no-no for me!