Ibanez Upgraded with John East Preamp

[SpondonBassed]

Like the title says, I'm installing a John East preamp in my Ibby SR605.  At some point I'd like to put some Nordstrand pickups in as well but for now, I have the amp to hand courtesy of @rk7.  He kindly gave me the old East pre from his Overwater bass after he had it upgraded whilst having the bass chambered.  The build thread is here.

I have been happy enough with the Ibanez from a playability aspect but the output is a bit bland with its current pre and licenced Bartolinis.  I'm exited to see if the East brings out anything interesting.

It is a five knob J-Retro (I think).  I'm winging it as far as resistance values and such are concerned.  Maybe it won't like the humbuckers that I'm going to couple up to it...  we'll see.  It's already looking like a tight squeeze unless I remove some body wood.  There is scope for that within the existing control cavity.

The John East Preamp with its long PCB

The Ibanez Preamp in its tiny cavity

The first important thing was to label the wires and photograph where necessary for reference for if I want to reinstall it.

Labelling

Pickup wire positions

I removed the control knobs and spindle nuts

Then with a few dabs of a hot iron to de-solder, the old preamp comes out (on the left).  After applying copper tape to the cavity to ground the control spindles as recommended by the East pdf, the new one goes in for a rough fit.

The board is too long to fit as is.  There is sufficient meat in the body adjacent to the output socket for me to carve out a niche for it (I think).  There should be no need for a larger cavity cover.

I put the East Knobs on to get a feel for it.  It's nice.  Beautiful action on the detents, the stacked knobs and the push pull knob for passive tone.  I only hope I can get some sound out of it too.

There is an empty hole where the mid frequency select switch went that I might fill with a dummy switch like Lee Sklar does.  He says that flicking it makes recording engineers think he's tweaked something too subtle for their ears to hear but like with the Emperor's new clothes they daren't admit it.

I'll leave off for now.  It's far too late to start carving wood.

Edited December 2, 2020 by SpondonBassed

[Tjhooker]

17 minutes ago, SpondonBassed said:

There is an empty hole where the mid frequency select switch went that I might fill with a dummy switch like Lee Sklar does.  He says that flicking it makes recording engineers think he's tweaked something too subtle for their ears to hear but like with the Emperor's new clothes they daren't admit it.

😏

[BassBus]

This is how to make a great bass even better. 

[Andyjr1515]

12 hours ago, SpondonBassed said:

There is an empty hole where the mid frequency select switch went that I might fill with a dummy switch like Lee Sklar does.  He says that flicking it makes recording engineers think he's tweaked something too subtle for their ears to hear but like with the Emperor's new clothes they daren't admit it.

  Yes - in various ways and various situations, I think we've all done similar things...works every time.

I think you will be very pleased with the John East - they are great little preamps.

[Woodinblack]

12 hours ago, SpondonBassed said:

There is an empty hole where the mid frequency select switch went that I might fill with a dummy switch like Lee Sklar does.

Not a bad idea. I put a glockenklang pre in my SR5005 when that preamp was a bit dead, but that has 4 knob pre, instead of 3, and also a bypass switch, which is covered by push/pull on the glock.

So one pot is a dummy and I am not sure whether to put the switch back in to fill the hole or put a low battery indicator in it. But I have never needed one so seems a bit superflous!

[BassBus]

14 hours ago, SpondonBassed said:

 

The Ibanez Preamp in its tiny cavity

 

I'll be interested to see what wires go on what terminals on the barrel jack. I have an East pre to fit in a Bass Collection with the same barrel jack and am left scratching my head as to what goes where.

[Woodinblack]

16 minutes ago, BassBus said:

I'll be interested to see what wires go on what terminals on the barrel jack. I have an East pre to fit in a Bass Collection with the same barrel jack and am left scratching my head as to what goes where.

I would think in that situation John Easts website will give you all the information you want, and if not, I assume the man himself will. Does this not help?

https://www.east-uk.com/wp-content/uploads/2020/06/UNI-PRE-01-3-KNOB-01-1.pdf

Also the wiring between the original pre and the east pre won't change the wiring, the output is still the same and the battery connections are still the same.

 

[SpondonBassed]

5 hours ago, BassBus said:

I'll be interested to see what wires go on what terminals on the barrel jack. I have an East pre to fit in a Bass Collection with the same barrel jack and am left scratching my head as to what goes where.

I have to confess ignorance.  Although I tagged each of the wires with a little diagram showing which tag it came from, I didn't make them clear enough to tell what orientation to look at the barrel jack from.

Doh!

I'm going to buzz the tags at some point to confirm which is tip, ring and ground.  It's easy enough by plugging in a cable and seeing which tags correspond to those locations.  I'll mention here when I do it.

[SpondonBassed]

7 hours ago, Andyjr1515 said:

I think you will be very pleased with the John East - they are great little preamps.

I am fortunate enough to have one in my Ray 34 coupled with a Nordstrand.  It's a combination I like more and more.  It will be interesting to hear what the preamp alone does for the instrument.

[Fishman]

On 01/12/2020 at 21:51, SpondonBassed said:

I might fill with a dummy switch like Lee Sklar does

I think that's known as a DFA switch 😊

I have John's uni-pre in two of my basses and a J-retro – top notch sound sculpting all round

[SpondonBassed]

58 minutes ago, Fishman said:

I think that's known as a DFA switch 😊

I have John's uni-pre in two of my basses and a J-retro – top notch sound sculpting all round

Yes.

The DFA switch operates without mains power too.  Not many people know this.  It's powered by a single PFM pellet that is embedded at manufacture and lasts for the life of the liar instrumentalist that's telling you about it.

Actually, the plan has changed with regard to the switch.  I need the room where the switch body was in the cavity for the main board on the Eastie beastie in addition taking out some timber from the inside.

The plan now is to try and put a little East badge in its place.  If I can legitimately do so that is. I must drop John East a line...

[Si600]

I don't remember, and can't be bothered to read back, but is this supposed to be reversible? If not, plug cutter, fill the hole and paint over it...

 

Edit: I have looked back and it's natural.  Find some nice wood and a plug cutter?

Edited December 5, 2020 by Si600

[Andyjr1515]

On 02/12/2020 at 12:22, BassBus said:

I'll be interested to see what wires go on what terminals on the barrel jack. I have an East pre to fit in a Bass Collection with the same barrel jack and am left scratching my head as to what goes where.

I think it's a standard stereo barrel jack.  If I remember (I've got to that age ) I'll take a photo tomorrow and mark up the terminals.

[SpondonBassed]

12 hours ago, Si600 said:

I don't remember, and can't be bothered to read back, but is this supposed to be reversible? If not, plug cutter, fill the hole and paint over it...

Yes.  I'd like it to be reversible but invisible on the outside save for the controls and a small East badge.  I can do it by removing material within the existing cavity.

I'm confident that it will fit snugly where indicated with some careful whittling.  You can see where my line intersects with the body of the original switch.

I have to be careful though.  The angled socket means I have to be absolutely sure where the first drilling goes prior to chiselling out to the final dimensions.

Up until now I have been working in the warmth of the living room in front of t'telly.  For this sort of work, I'm waiting for an opportunity when I can make enough time for it to be worth heating the workshop as it is not on the main heating system.

Also, this is risky.  I have to be centred, as they say, before I dare power up the Dremel.

Edited December 6, 2020 by SpondonBassed

[Andyjr1515]

This one has a wire clasp incorporated into the Ground tab, but the principle is the same on all of them.  Basically the stereo barrel jack socket, just like the standard clip-type stereo jack socket, has three tabs:

One is clearly on the outside of the barrel and then there are two more coming through the insulated disc: one is short and one is longer.  On this pic, the outside one (with in my case the cable grip) is on the left, the shorter one is in the middle and the longer insulated one is on the right.

The one on the outside (left in pic) is the Ground

The short one through the insulation (middle in pic) is the Tip

The longer one through the insulation (right in pic) is the Ring

 

 

So if you were wanting to use a stereo jack for a stereo output, then one hot signal would go to the tip, the second hot signal would go to the ring and the ground would complete the circuit.  The red triangles here are the spring clips that make the contact with the jack:

 

 

But if you put a mono cable - like a bass amp cable into the socket, then the shaft of the jack shorts the ring to ground:

So the folks much cleverer than me have mused, "Hmmm...we could use that to turn off the preamp when the cable's not plugged in.

So basically, you wire the black lead from the battery holder to the ring and so when you push the jack in, it connects the -ve battery to ground and therefore makes the connection to turn on the power to the preamp, and when you pull the jack out, it breaks the connection and switches the preamp off.

Which is why you never leave a pre-amp'd bass plugged in when you are not using it

Clever stuff.

 

 

 

[SpondonBassed]

8 minutes ago, Andyjr1515 said:

the stereo barrel jack socket, just like the standard clip-type stereo jack socket, has three tabs:

Excellent!

I would've worked it out step by step but that encapsulates it all nicely for me.  Thank you.

Now I can work out why the Ray34 eats batteries unless you disconnect it despite being unplugged as well.

[SpondonBassed]

As has been said by @Andyjr1515 among others; part of the pleasure of doing this is being able to take time out to work out the best way to achieve a desired result with what you have to hand.  It's easy to get caught up in a wave of enthusiasm and then go kak it up.  For the sake of a little restraint all the work to that point might as well be written off.

I've been trying to work out by eye how to conceal the East's long PCB behind the existing control panel cover by removing just enough wood to make it slot in obliquely across the cavity.  I stopped to think how best to choose the exact centreline for the PCB before I start the cut.  Using the amp itself is not a great idea because of the risk to the soldered connections through repeated bending of the many wires during the trial fits.

I needed a gauge that represents the loaded PCB dimensions closely enough to serve throughout the job.

I started with a baton of the same thickness.

 

Then I traced the outline of the PCB allowing for a little over where some wires exit from the end of the board.

 

A few cuts with the tenon saw and a quick rub on some Abranet and we have a gauge.

That's all I can get done today.  I am exited so it's perhaps for the best.  It'll allow a bit of time for me to cool off.