JapanAxe

Thanks, I came across these when I was looking into options. I drew out the circuit in the OP and added in the second cross-connection as per the lower diagram, then compared the two. The OP circuit simply puts a resistance (let's call it R) in the path of one of the pickups at a time, to attenuate its signal. The effect of adding the cross-connection is to add a second resistive path in parallel: At zero attenuation there is no difference. At maximum attenuation the resistance in series with the pickup is now ½R instead of R. At the halfway point, it becomes ⅜R instead of ½R, so the taper of the blend has changed. Also with this circuit you wouldn't get the effect of completely disconnecting a pickup if you cut the resistive tracks near the end. It would be a quick and easy thing to try though. In the upper diagram, the second cross-connection is tied to ground, which is a different approach altogether and has the effect of loading the pickups, which the OP circuit doesn't.

I mentioned earlier today I had 'another idea' - I've implemented it, and it works! When thinking about what didn't work for me about the stacked-knob setup, the main issue was the tone pot taper, where there was little effect until the bottom quarter turn of the pot. I removed the extra 56nF caps and added a 510k resistor between the wiper and the 'hot' lug of each tone pot, thereby converting the existing 500k tone pots to 250k with a somewhat different taper. The tone pots behave much better! Curent plan is to to stick with this, but also acquire a 3-control plate and build it as Vol/Switch/Tone or Vol/Blend/Tone. Watch this space...

That’s the thing, once you back off a stacked volume control or a VVT volume more than one notch out of 10, I don’t hear any further change. EDIT: Hoping for more variation on a blend…

Well spotted! The bass came without the correct 6-32 intonation screw (actually a bolt). The original would be 1 7/16in (39mm) long. I sourced some 2in bolts and cut one a bit longer, as I suspected the original had been lost because it didn’t adequately engage with the bridge saddle. This topic is crying out for a PhD thesis!

What does the Turbo switch do? I’m kind of afraid to ask…

Yes that may be the way to go. I keep having to remind myself that this bass is basically a MIM Roadworn with some extra relic’ing, not a vintage instrument! A couple of Christmases ago I woke at 4am, and was still awake at 5am, so I got up and (with the help of a YT video) replaced the heater roller in my laser printer. That put me in a good mood for the rest of the day. In the meantime I’ve had another idea…

I decided it would be good to keep at least some of the stack-knob look by turning one volume/tone pair into master controls, and replacing the other with a rotary pickup selector or blender, using just the chromed volume knob. But can I hell get the volume knobs off? It feels like the screws have been tightened with one of those air tools that tyre fitters use. I have tried WD40 and heating the knob with a soldering iron, so far without success. The grub screws are slot-head types, and as I apply more torque the screwdriver blade starts to distort, or the blade cams out of the slot - you can only do that so many times before the screw is mullered. Any tips folks? And if you're wondering why I'm sat doing this on Christmas Eve, we've just had tea with the grandkids, and Mrs JapanAxe has sent me to my music room while she does some last-minute wrapping!

Exactly what I was going to recommend. I recently put one on my main lead guitar pedalboard to mix in wet-only signals from two delay pedals. It works a treat and was stupidly inexpensive - less than £50 on Amazon, even cheaper on eBay. It’s a clone of the discontinued OBNE Signal Blender.

I’ve never hankered after the series option, in fact I rarely use it on my Dingwall NG2. I’d be interested to see how the two volume controls interact in series mode.

With this circuit, centre position on the blend control means both pickups are connected direct to the master volume and tone controls, so that would be equivalent to both volumes maxed in a VVT setup as you say, needed to reject RF interference. Neck full / bridge 20% should also be achievable.

I've just finished reading most of the 18-page Talkbass thread, which runs from 2014 to August 2025! I'm going to go for a 100k MN blend pot and cut the traces for full isolation at the extremes, so I've ordered a pack of 5 via eBay. If I don't like it, I've found there's room in the cavity to fit a rotary selector switch.

My stack-knob Jazz is definitely bright compared to my Precisions, but I enjoy the contrast.

I’m on board with ‘simple’ but I do like to ride the tone control from song to song.

Just because you could do something doesn’t mean you should!

I recently acquired a lovely Jazz (having sworn off them for a good few years) and I find myself facing the same first-world problem that I always have - quick changes to the sound. I know that many people swear by the Volume/Volume/Tone (VVT) setup, and like to juggle the volume controls for subtle changes. Frankly I find these too subtle to be worth bothering with, and I converted my last Jazz to Volume/3-way switch/Tone, a bit like a lot of the passive Yamaha BBs. My current Jazz is a stack-knob with the later variant control circuit (no mixing resistors) and I'm starting to think a little modding might be in order. The everything-on setting alone is worth the price of admission but I have the same issue as with the VVT in that there is only any tonal change over about 1/10 of a turn of either volume knob. It has 250k volume pots but 500k tone pots, so very little happens to the tone until the bottom quarter of the pot rotation. For now I have tacked a couple of 56nF resistors in parallel with the existing 50nF ones, which has improved things from my point of view. I'm currently considering getting a 3-knob control plate and setting it up in one of the following ways: Vol/3-way/Tone Vol/Blend/Tone as per the diagram below - I originally found it on Talkbass but then found that @TRBboy had posted this thread about it last year. I could easily try both and see which I liked best of course So - what passive blends have members had success (or not) with, and who gave up and either fitted a 3-way switch, or returned the bass to stock?