Ibanez SR preamp hacking

[geoham]

Hey guys,

 

I've been using an Ibanez305E as my main gigging bass for the past few months. While it's fairly entry level, the weight of it means I avoid backache the next day. It plays well enough, but I miss the safety net of a preamp bypass and flexibility of switchable mids that my last bass had. I also don't really need the coil-tap, but no harm in it.

I had a poke around inside, with a view of perhaps upgrading the pre-amp and maybe the pickups too. I noticed the pre-amp module has unconnected mid-frequency and bypass sockets.

 

I'm wondering how best to utilise them? Ideally I'd like to replace the volume with a push-bull to control the bypass and a dual-concentric mid controller - both with drop-in parts similar to the solderless connections already in there. Presumably they do exist and are being used on other models, but the power of Google isn't helping me find what I need.

 

Alternatively, I know I could hack something together with regular pots - I'd just need to know where to find those little push-in connectors to attach to the PCB.

 

I'm really keen to hear from anyone with any knowledge, or experience in upgrading the electronics on these basses.

 

Thanks,

George

[itu]

Mouser, RS, all big electronic component dealers should have, if not the same, then similar connectors. And pots. If you find a beaten Ibanez, you could ask for parts.

[PaulThePlug]

Loves an SR... for a few...

As for the electronics try Ebay - 4 Pin PCB Connectors.

 

Some SR like my SR600 had a Mid Freq Switch, others had a dual concentric 'sweep' pot.

 

I have gone the other way removing the pre and gone passive.

 

SR300 with a Single Tonerider P

 

SR300 with 2 Maida Vale Stacked Jazz

 

SR400 with 2 DiMarzio Twin Coil Jazz

 

[geoham]

31 minutes ago, PaulThePlug said:

Loves an SR... for a few...

As for the electronics try Ebay - 4 Pin PCB Connectors.

 

Some SR like my SR600 had a Mid Freq Switch, others had a dual concentric 'sweep' pot.

 

I have gone the other way removing the pre and gone passive.

 

SR300 with a Single Tonerider P

 

SR300 with 2 Maida Vale Stacked Jazz

 

SR400 with 2 DiMarzio Twin Coil Jazz

 

Thanks, that's helpful about the 2 mid frequency options. 

I do like the Tonerider P pickup - one transformed my old Mexican P immensely. The red one look the best though - lovely.

[lemmywinks]

I have a box of connectors at home, if you put a pic up of what they look like (inc where the locating ridges are) I can see if they're compatible. You can also buy Ibanez preamp spares online from Banzai, Meinl etc, think Thomann did them at one point.

 

Assuming the bypass connector is 2 pin it may just be a simple switch so that should be easy to rig up to a push/pull if your current volume pot is just a standard potentiometer. Spares from the other Ibanez 3EMP preamps might fit, the mid and mid freq switch were sometimes linked with two separate connectors so you might need to buy that whole assembly.

[geoham]

6 minutes ago, lemmywinks said:

I have a box of connectors at home, if you put a pic up of what they look like (inc where the locating ridges are) I can see if they're compatible. You can also buy Ibanez preamp spares online from Banzai, Meinl etc, think Thomann did them at one point.

 

Assuming the bypass connector is 2 pin it may just be a simple switch so that should be easy to rig up to a push/pull if your current volume pot is just a standard potentiometer. Spares from the other Ibanez 3EMP preamps might fit, the mid and mid freq switch were sometimes linked with two separate connectors so you might need to buy that whole assembly.

Thank you, I'll get in to again and see if I can get a good picture. 

[geoham]

Having spent some more time a bit more time trawling the internet, I've found the parts I need for the mid-frequency mod. However, I've no idea where (or if) I can buy these!

 

Dual concentric pot:

https://cs.hoshinogakki.co.jp/pcw.nsf/item.xsp?documentId=0C425671AE1BCBD449258A580032410A&strItemKey=3VPVM44A__5C_01&curSuffix=5C01&curFromYMTX=&curToYMTX=&strMode=newpage#

 

4 pin connector cable
https://cs.hoshinogakki.co.jp/pcw.nsf/item.xsp?documentId=0C425671AE1BCBD449258A580032410A&strItemKey=3CH4075HH__5C_01&curSuffix=5C01&curFromYMTX=&curToYMTX=&strMode=newpage

 

There's a link to a parts catalog on the Ibanez site. From there, I could find the same pre-amp module - then other basses it was used with, and found one with a sweepable mid.

 

Regarding the bypass - it appears that this is a non-starter. There are two almost identical versions. Mine, which says 'Bypass short' and another that says 'W / Bypass'. It appears that all basses with a bypass switch use the latter. I tried simply shorting the pins, but it has no effect. Following the PCB tracks, it looks like they are shorted on the board. Seems a weird design choice - probably done to keep manufacturing costs down.

 

@lemmywinks Below is a picture of the 4 pin connector for the mid-frequency control. If I can't find the above part, I may just use a generic pot if I can find the correct connector type. (I'll also need to figure out how to wire a 3 pin pot to 4 connectors - 3 are labelled "SIG' and one "BIAS". But that's a problem for another day!)

[Obrienp]

I wrestled with how to make a passive switch on a Mezzo, which is also active only OEM. The trouble is you have to build a whole separate passive circuit, if the preamp isn’t set up with a passive option. Easily checked by removing the battery and seeing if you get a decent signal at the jack, or not. In the end I gave up on the standard preamp (which was crude anyway) and got a Glockenlang with a built in passive option, including tone control: much easier in the long run and much better than the OEM.
 

As it happens I am selling the Glockenlang but it’s only two-band, so won’t be of interest to you. There are plenty of 3 band replacements, which offer push/pull active passive and sweepable mids, with various numbers of knobs (some using stacked pots). A lot less hassle in the long run but I suspect you like the challenge 😀.
 

[geoham]

On 06/08/2024 at 17:47, Obrienp said:

I wrestled with how to make a passive switch on a Mezzo, which is also active only OEM. The trouble is you have to build a whole separate passive circuit, if the preamp isn’t set up with a passive option. Easily checked by removing the battery and seeing if you get a decent signal at the jack, or not. In the end I gave up on the standard preamp (which was crude anyway) and got a Glockenlang with a built in passive option, including tone control: much easier in the long run and much better than the OEM.
 

As it happens I am selling the Glockenlang but it’s only two-band, so won’t be of interest to you. There are plenty of 3 band replacements, which offer push/pull active passive and sweepable mids, with various numbers of knobs (some using stacked pots). A lot less hassle in the long run but I suspect you like the challenge 😀.
 

I do indeed like a challenge. Although replacing the pre-amp with something a bit more capable is probably a good idea. I may even do the pickups too.

This is my main gigging bass now due to its light weight and it didn't cost me much, so don't mind spending a few quid on it.

Cheers,

George 

[basstone]

Does anyone out there have a schematic or even a simple wiring diagram showing how the controls connect to the board? The 3 sig and ground is probably fairly straightforward but for the middle frequency with 3 sig plus bias it is not obvious how to add this in. Maybe someone with an SR Ibanez with mid sweep could trace it out. It would be a really good asset for the Ibanez owners on the forum. As for the connectors, they are readily available from multiple sources including:

 

https://www.ebay.co.uk/itm/134781932915?var=434274031445

 

It pays to get the correct wire size and a good crimping tool to make reliable professional quality pin connections.

[geoham]

18 hours ago, basstone said:

Does anyone out there have a schematic or even a simple wiring diagram showing how the controls connect to the board? The 3 sig and ground is probably fairly straightforward but for the middle frequency with 3 sig plus bias it is not obvious how to add this in. Maybe someone with an SR Ibanez with mid sweep could trace it out. It would be a really good asset for the Ibanez owners on the forum. As for the connectors, they are readily available from multiple sources including:

 

https://www.ebay.co.uk/itm/134781932915?var=434274031445

 

It pays to get the correct wire size and a good crimping tool to make reliable professional quality pin connections.

 

The only thing I've been able to find myself is the dual-concentric pot, which also has a 4 pin connector. I know the basics of how a potentiometer works, and can't quite figure out what a 4th pin would do. (From https://cs.hoshinogakki.co.jp/pcw.nsf/item.xsp?documentId=0C425671AE1BCBD449258A580032410A&strItemKey=3VPVM44A__5C_01&curSuffix=5C01&curFromYMTX=&curToYMTX=&strMode=newpage#)

 

What I though would be a straightforward mod may be a little more complex. 

 

That little crimping set does look like a useful tool though, it would also make swapping the pickups a much easier task - thanks.

[basstone]

5 hours ago, geoham said:

 

The only thing I've been able to find myself is the dual-concentric pot, which also has a 4 pin connector. I know the basics of how a potentiometer works, and can't quite figure out what a 4th pin would do. (From https://cs.hoshinogakki.co.jp/pcw.nsf/item.xsp?documentId=0C425671AE1BCBD449258A580032410A&strItemKey=3VPVM44A__5C_01&curSuffix=5C01&curFromYMTX=&curToYMTX=&strMode=newpage#)

 

What I though would be a straightforward mod may be a little more complex. 

 

That little crimping set does look like a useful tool though, it would also make swapping the pickups a much easier task - thanks.

From the picture, I suspect that this is a dual gang 20K pot(C taper) and a single  gang 10K (B taper). That makes some sense as often variable frequency middle controls use a dual gang pot for the sweep and a single gang for the level.