ACG EQ01 in Cort B4

[DorsetBlue]

Similar to Steff's recent Audere topic, I thought I would do one on my current modification to my Cort B4. I love my Cort, it is excellently built for the price (although found one defect doing this, see below) but I have never got on with the preamp in it - most of the time I just run it in bypass mode. After recently acquiring a ACG Graft which didn't have one of Alan's filter based pre-amps in it (single pickup), I thought I would buy one of the EQ01 preamps and fit it to the Cort, to see if I could get my head around a filter pickup before maybe ordering a 5 stringer with one fitted in the future.
I was intending to do this all today but the repair (see below) will need 24 hours to dry, so I thought I would put post 1 on now.
Here she is before any work:



Note that it has 5 knobs plus the bypass switch, so I have bought the 5K version of the EQ01. I intend to fill the gap left by the bypass switch with a battery status LED from John East if this all goes according to plan.
On removing the back cover I found that the wood has split around one of the screwholes, this is the repair that has been done.



There is pretty good screening inside, with foil on the cover underside and conductive paint used throughout, so I am umming and ahhing about putting anymore in. The Bartolini pickups are apparently split coil humbuckers and I have never had any problem with noise up to now. One to think about before the installation phase.
All of the knobs were allen key secured, so they came off easily. I have written numbers on top of the pots for future reference (re-installation or if selling).



Removing the existing loom was very easy. The existing preamp was installed with in-line solder joints with heatshrink covers for the pickup connections and battery connections. The outputs to the jack are soldered directly to the volume pot and there are screen wires to the bridge and pickup cavities, all soldered to the shell of one the pots. A quick application of the soldering iron and these were all disconnected.



So the preamp and associated loom largely comes out of the bass as one unit. I put some tags on the in-line wires, again for future reference and the pots that had soldered connections also were additionally numbered on the bottom too (there were additional photos taken during de-soldering again for future reference).



So the Cort is currently sitting in the conservatory whilst the glue dries on the repair to the screw hole. My guitar tool proved to be just the right size to act as a clamp.



I hope to do the installation phase tomorrow, depending on whether my girls want to go out somewhere (half term!).

[DorsetBlue]

Managed to spend a couple hours on the bass last night and have progressed things somewhat. After re-reading the manual/s, I noted that Alan recommends you still use foil where the pots touch the bass even with screen paint - so I stuck some tape in this area and also improved the earthing to the backplate whilst I was at it.



I used my multimeter to confirm that there was very low resistance between the strips of foil, I also attached a new common cavity earthing point to the strip of foil going to the back plate. Now it was on to fitting the units that make up the EQ01, which is a modular design. This has significant benefits in some ways but has a couple of drawbacks for retrofits.



Drawback one, in your excitement to get everything fitted you may install all of the modules into the spaces you want them...you may also secure them in space. It will be at that moment you realise that the, admittedly very nice to have, screw terminals have the screw holes in the horizontal and the wire attachment holes in the vertical. Now although you need to use a very very small electricians screwdriver to tighten these terminals, you cannot do this in a populated cavity - there is not enough room, so you have to take everything out again and wire it up before inserting the modules. Luckily I realised this with only the main board and one of the LF boards fitted. In my opinion, it would have been better to have had these terminals with the screw head in the vertical. This would allow for in-situ wiring, still it is only a minor niggle.
Drawback two, these modules are quite bulky when faced with a cavity that has been routed for pots and a single pre-amp board. This does limit your orientation options somewhat and makes routing of the interconnecting ribbon cables a challenge. In my case, this has proven impossible with the length of the ribbon cable provided to reach the terminal of the bridge LF board. Not to be daunted by such a minor engineering annoyance, and noting that the ribbon cable is really just a 5 conductor solid core cable, I intend to create an interconnection cable from an appropriate equivalent - probably either Cat5 or telephone cable.
Unfortunately I cannot show any photos at this point, as my smartphone decided to die for some unknown reason overnight. Hopefully service and the fit will all be back on schedule shortly.

[skelf]

Drop John East a line he may be able to supply a longer flexi.

[BigRedX]

In order to get the pots of the ACG EQ01 in the positions I wanted them in my Pedulla Buzz, Alan supplied me with a ribbon cable extension.

[DorsetBlue]

[quote name='skelf' timestamp='1392981941' post='2374863']
Drop John East a line he may be able to supply a longer flexi.
[/quote]

Thanks Alan, that is an option. However I think the bend radius required might be too extreme for this ribbon cable. Just going to have another gander at it to see.

[DorsetBlue]

Perhaps it just needed a sleep break but after re-looking at the routing, it was possible to get the ribbon cable to reach (although it does indeed have a bit of a bend in it.



Just had the battery back in and plugged it into the amp - it works!!! Well kind of.
The preamp is definitely working but the bridge LPF is markedly stronger in it's effect than the neck, so I think some tweaking with the level pots on the LPFs is in order. I did take the bridge pup out last night (was hoping that it might have some extra lead length cable tied back in the cavity, alas this was not the case hence the Orange/Green extension I have had to solder inline) and noticed that it had an 'R' printed on it. I suspect this means it is actually a Neck pickup, which I believe is the same case on the Ibanez SR600, showing that these basses are essentially the same except for the Ibanez neck profile. I think this means the bridge pup is rather stronger in its output.
So hopefully this means I just have to do the tweaking and then final fittings, which will lead us to an issue with one of the knobs I have bought from AxesRUs for the Passive Tone control. But that will have to be later, swimming awaits apparently.

[HowieBass]

Wouldn't 'R' stand for 'Rear' pickup? I've a B4FL and have both pickups set at essentially the same height which, as I think you're suggesting, means the rear/bridge pickup has a higher output than the front/neck pickup (which I find convenient as I have a makeshift ramp between both PUs with everything at about the same height).

[DorsetBlue]

You could be right, I was thinking in Gibson mode where R=rhythm and I was assuming the other pickup would say T. Not going to take it out to check though now, have the finishing line in sight. :-)

[DorsetBlue]

Right, after a day driving around Poole/Bournemouth looking at cars - managed to get back to more important stuff. It was just a case of putting everything back together basically. However, one final issue arose at this point, the knob (actually they sent me two by mistake) I had bought from AxesRUs, whilst great for the concentric pots, turned out to be for a splined 6mm pot and not a smooth one - which the Passive Tone pot is.



I attempted to drill the splines out of the first knob but that has produced a result that is less than satisfactory (it doesn't turn flat) and after looking at the Knobs on my ACG, which are bigger and look far more in keeping with the concentric pot knobs, I have decided to pick up another proper knob from John East when I order the battery status indicator from him in the next week or so. So here the nearly finished result is:





So aesthetically speaking I am reasonably happy. The stacked knobs look excellent and have a nice weight behind them. Definitely recommend them and they also have the, I think essential for this Pre-Amp, position markers. Once the remaining hole is filled with the LED and Tone knob is changed, its going to look nice.
Now for the far more important functional result. I have not had anywhere near enough time to play with it yet but even my girlfriend was staggered by the difference in sounds that could be produced by this Pre-Amp, it is an amazing piece of kit. It is such an upgrade from the original MK1 preamp as to be incomparable. I was umming and ahhing about upgrading the MK1 pups but they seem to work really well with the EQ01, so I don't think I will now.
It is all packed up and in a hard case now, ready for transport up to the Dorset Bass Bash.

[DorsetBlue]

Right, last bits done. The Battery Status Indicator and Knob arrived from John East on Friday:



The BLI-01 is very easy to install, it is just wired to the Battery +V and Ground connections:



Then I desoldered the 18V wire (Orange) as it was not needed and then soldered the LED wires into place:



Then it was just a case of putting it all back together. Not managed to test the LED yet, tried putting a Rechargeable PP3 (7.2V) into the bass but this is obviously not low enough voltage to set the LED off (the EQ-01 is running fine at this voltage).
The John East knob for the Passive Tone control fits perfectly and now fits in better with the other knobs already used. So I am content that this is job done, very happy with the results and still playing around with the pre-amp (found a few settings that I really really like). Definately recommend the EQ-01 for retro fitting.

[BassBus]

Nice job. I've just started using one of these on an ACG and getting to grips with it quite quickly. Some good tones from it.