Revised Passive Treble Bass Midrange (PTB-M) for HH

[frets]

Hi Guys, Happy 2021!!

As most of the gang know, I’m high on PTB systems and have been attempting to integrate a Midrange Control within Wiring that maximizes it’s true effect without muddying the tone.  I had, some 9 months ago, posted a PTB-M Wiring; however, I have revised it.  The following incorporates the Midrange without darkening the tone as much as the original; as well as, improving upon the usability of the bass cut.

[ssstonelover]

Kind of a long shot but do you have any ideas on adapting this to a P/J bass?

[frets]

Hi SSStonelover,

I have actually done a bass using a concentric pot, a midrange pot and a regular volume pot. The first concentric does the treble cut and bass cut. It uses 47nF and 4.7nF caps, the midrange pot is the typical midrange pot. I will try to remember to draw it up for you.

[ssstonelover]

Thanks, I'd like to see that. I have 4 pot holes to work with, so yes, one or 2 concentric pots makes sense... to cram in everything needed.

[frets]

Hi ssstonelover,
I was getting ready to post the wiring and then noticed it is a PJ bass.  I drew one up for a P bass! (My attention deficit).  I’ll have it up in a day or two.  Sorry for the delay.

[frets]

Hey ssstonelover,
Here is your PJ Bass harness using 3 concentrics.  I threw it together quickly.  You’ve got your Volume/Midrange, Passive Bass and Treble Cut and the Bridge/Neck Blender.  I built this wiring for a PJ about 2 months ago using Alpha Mini Concentrics. Without Center Detente’s.  I’d say the minis are a must.  You can find them on EBay for about $7.75 USD a piece shipped. I remember when I made it I did not use orange drops - too big.  I just used greenies.

[ssstonelover]

Thanks for that!

Just saw your post (sorry about that) and it looks perfect. I use greenies and Alpha pots almost exclusively, so those will not any issues whatsoever.
For this build I just received the Guitar Fuel Tone Monster SBK-3AD (my P/J copy has 4 pot holes strangely enough) so I'll use your 3 pot schematic on the next build. Probably won't be long as I have another bass perfect for that!

[ssstonelover]

Hi Frets,
Getting ready for the next P-J build!
--For the mini concentrics, any preference between the 250K or 500K for the blender pot? I'm guessing there is no functional difference, and that all the pots at 250K makes the best sense, but maybe not as this is a PTB-M system. Let me know.

--Also I checked your drawing and had a question about the Xicon 42TL018. You show it attached in 2 places, but the Xicon drawing shows 6 leads with a primary and secondary side, and I haven't used these items before... so want to match up your shorthand to the actual part...and get the soldering right, and know if there is a side orientation. Thanks!

[frets]

High Ssstonelover 😺😺!!

Actually, I favor A500k pots. I find it has more tonal range with 500k’s.

On the Xicon Mouser Transformer you’ll see a “P” in the middle of it. Go one over to your right and cut that middle leg. Now, you have two legs on the side with the “P”. Next, cut off all the three legs on the opposite side. You now have a two legged transformer. The cap goes into the first leg and the second leg goes to ground. Easy Peasy. I think you’re going to like it.

[ssstonelover]

Hi Frets,

Ok, think I understand. it should be arranged this way (x = removed leads)
I did notice the resistor is in a different location between the guitar (parallel to the cap) and bass iteration (in parallel to the transformer) of the design. Is that intensional?

[frets]

Ssstonelover, the resistor goes between the legs of the capacitor. In parallel. I will draw you a picture tomorrow 😸

[ssstonelover]

So it should look more like this ...?

[frets]

Yes, that’s it. Did I leave the resistor off of my diagram? I’m sorry. But you’ve got it right.

[ssstonelover]

Hi Frets,

I really did not mean to hijack your post and morph it to bass, so it's a good thing you like them too! Thanks for being gracious! This is real interesting stuff you've got going.
Could you go through this new iteration and let me know of issues? I spent some time comparing it to other PTB circuits at Rothstein and on a bass site, and outside of some discretionary items (cap values) some of the wires leads in slightly different places. \
If the electrical truth is the same, that's no big deal, but if it is... and as this is my first PTB/M I'm a little more hesitant than where I know the footing well.

I noticed that some others have 1000K resistors on the treble or bass pot (hm)....and I left an unmarked resistor attached to one bass pot which can be either eliminated or given a value (it was on your HH guitar version interestingly).
I'm mainly showing 500K pots based on your input, but should I be looking at Linear taper for the tone pots? I hate tone dropping off a cliff and could use your advice. I have both A and B taper pots in 500K
If you like what you see and/or have some minor update the soldering and testing, then move the final drawing to a new thread with credit to you (of course).

The big change is that I routed out the control cavity to accept lots of pots, so there will be no need for concentric pots and so there will be less fumbling around. I know this is a bit different that the usual strictures of P/J basses, but I love woodworking.
If the orientation look a bit strange is simply a leftie build.




Thanks, Bethi

[frets]

Bethi, we gals need to stick together!! You didn’t hijack anything and your diagram is absolutely gorgeous and correct. You don’t need the 1M resistor on the bass cut. Not with single coils. Gosh, it looks great. You’re going to love it. If you need a 2.65H 42TL018, just PM me and I’ll mail you one. I got a deal on 60 of them. Ha! I love working on bass guitars and you’re right, the Ibanez Bass’ have plenty of room in the cavities. I would stick with A logarithmic pots. That’s just my preference. I don’t think you’ll find any drop off in this system. I just love your diagram.

[ssstonelover]

Thanks Cindi,

I will order the missing parts from eBay, but thanks for the offer. I'm in the greater Los Angeles area, if you just happen to live somewhere close, though that's unlikely!

* 1M Okm resistor: I removed it though technically the P-bass pickup is a (split) humbucker LOL
* I saw that the blue wire from the volume pot to the treble looked unnecessary as the purple wire from the bass pot was already making a connection the the treble pot, meaning the blue wire might confuse the bass filtering. I further noticed the HH diagram had no such corresponding wire, so take a look at that to confirm if the blue is redundant and even negative and that I took the right action.
This update shows the 2 changes, and I better labeled the pots



The cavity started pretty small, but I have routers, bits, and can make a  paper 'blueprint' and then make the templates for routing. On this one I even plugged the existing holes (kit body) so i could really be free to place all the holes most efficiently.
The test fit turned out OK, so some final drilling, staining and painting before the final parts arrive and I start soldering this up.



Beth

[frets]

Beth,
Everything looks terrific!!😺😺

Nice rout. I love working with the wood. That’s probably my favorite part of building a guitar.

I’m so far away from LA. I’m down here in NC. I get some good Swamp Ash down here if you ever need any. I get a lot of good wood down here. I hope you’ll continue to show your bass as you move along. It’s exciting !!

[ssstonelover]

Hi Cindi,
OK, let me give you the update. The bass is done (parts took some time to arrive) and it looks nice (picture below).
Unfortunately the 3 tone controls are not correct as installed (the balance and volume work fine however).

Treble control: this will be an easy fix of adding a wire (already tested with jumper cable and alligator clips, so not a real issue.

Mid control: No idea what's wrong, as I followed both your drawing plus my revision pretty precisely. What I can tell you is that when the knob is rotated the volume is killed entirely. I did find I goofed big time on the cap value by a factor of 10 (misplaced zero) but that should only effect tone not kill volume (I think). In any case new caps are ordered so I can make the substitution to 33nF soon.... I also measure the Xicon Henry value and come up with 1.2H (not 2.6H) but based on some of the other conversations I've had here that is normal as this is frequency based?

Bass control: Twisting the knob has no effect in tone or volume.... I noticed the wiring I copied/transposed matches your ideas, but not that of G&L PTB (or other tone circuits) but as you have made this circuit before I want to get your advice before i desolder the pot and try alternatives with alligator clips.

Hope you and the gang can get me going. Thanks!

Beth

[frets]

Hi Beth,

First off, let me say I’m so sorry you’re having this problem, it is frustrating when guitar harnesses don’t work. Later today or tomorrow I’ll thoroughly review the wiring. I have the same harness in an Ibanez SDGR and it works. I’ll be back a new diagram or thoughts. It should be working.

[ssstonelover]

Hi Cindi,

I appreciate that and no need to be sorry. This is one that took me a few days to figure out until I had my eureka moment link

The replacement 0.033uF/33nF CAP (for the mid control) probably won't arrive until Thurs/Friday so there is no rush and fortunately this is not a customer's axe.
I really blew proper cap value on the first pass and was off by a significient digit on the first order 0.33uF/333nF so that's on me entirely.

[frets]

Beth,

I think I see the error and this would be my fault. On the bass cut, break the link between 2 and 3. Move the .0047 to 2 & 3. Let me know if that works.😇. The Midrange pot looks correct. I know you have to wait on the cap, but you have the cap in parallel with the 220k, running through the transformer (into leg one on the P side) and out to ground on leg 3.

Before I wire it up, let me know.

[ssstonelover]

No worries. I'll do the bass pot in the morning....need to do some bass practice right now..
As far as the mid pot, I used 300k for the resistor in parallel with the cap (you had 300K on the drawing). I'll adjust as needed, just let me know your current thinking. I do have some 220K if you think that's a better choice now.

[frets]

Beth, 300k is right, I was thinking electric guitar.

[ssstonelover]

Thanks for confirming 300K (mid control)

I did go ahead and play with the bass cut...

I tried a number of combinations:

1. I cut the connection between leg 2 and 3 and moved the .0047 cap there as suggested and soldered it all back together. No tone difference (regretfully)

2. I then tried the "G&L" way (see drawing) after desoldering all from the pot and then alligator clipping the circuit back together. No tone difference.

3. I tried the "Rothstein" way (also on drawing), same situation, no tone difference.

I also (to make sure I'm not losing my mind) checked the pot and it works normally between 1 to 421K (A500K nominal value). The cap is actually 4.8nF (.0048uF) using the multimeter...

I'm wondering now if the cap value is too low...I have not tried bigger caps to see what happens, or if there is something else we're missing

[frets]

Beth,

Give me a day or two to rebuild the whole thing and track down my error.

[ssstonelover]

Cindi,
I did some more experiments this morning and they are pointing to another and simpler to solve issue. In other words I don't think the bass cut control circuit is fundamentally flawed, but that the issue is likely other wires. I refer to your original HH diagram and the connection to SW1 from P2, the magenta wire connection (though it is different from you bass ideas). The White wire is moved from the volume pot to the treble pot and from there goes to the balance pot (sw1). 
This also would follow the idea on this link tonefiend.com/guitar/two-band-ptb-tone-control-useful-easy-cheap-awesome/ which has a lot in common with your HH (less the mid control of course)

I'm thinking that needs to copied to the bass harness (see revision below). What do you think!

[frets]

Beth,

I think that might solve the issue. I see your point. If this fix does not work, I will rebuild and find the error. I’ve just been up to my neck in guitars. Please know I’ll help you in any way I can. Once the wiring is confirmed. I will update my diagram for guitars. Your diagram is beautiful,
Cindi😸

[ssstonelover]

Cindi,
Switching the white wire does deal with the issue. I did a test with alligator clips and lots of leads.

I did notice cutting the bass also affects volume which makes sense as most of the volume is in the low end since it's a bass (hm).... but I may try with another cap to see if I can control it so the effect is less. I noticed the control is 'backward' as it is a A500K pot (not a reverse log taper "C" type assuming you can even buy one).... I can live with that unless you have some ideas.

The treble works normally....as mentioned it's pretty light, but I have plenty of caps, and anyway need to wait until the 'real' mid cap arrives so i don't overlap the cut frequencies.

Here is a fun pic for you LOL

[frets]

Oh my goodness!! I’m glad you got to the bottom of it and again, I’m sorry you had to go through all this work.

I just love how you finished the bass. Is that a Crimson Guitar Water Based Stain?😺

[ssstonelover]

I used the Keda Dye stuff (water based). Easy buy from eBay plus the info on their site and on Youtube is pretty straightforward.
The only mistake I made was unrelated. I sprayed 2K directly over the dye and the end grain kept soaking it up like a sponge instead of building.
Usually I seal with CA (Gluboost) but I did not this time as it was not an open grain (probably bass wood so did not need pore filling plus I did not want to sand back and expose raw undyed wood inadvertently). Next time I'll wipe on shellac as a sealer with a little build.... such as silly mistake. It took two cans of 2K instead of one (had to let can one to dry and do a first rough flattening for adhesion, so one day extra and $20 of extra paint.... yeech.

After I get the mid cap I'll see if I can balance all the cuts and make a final posting -- assuming it does not cause any fits, fingers crossed .