You know, a lot of guitar players could be interested by this concept. They rarely blend, like to use multiple very different pickups and love accessing their preference settings at the toggle of a witch.
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Natural tone preamp
- Thread starter Jeff Siddall
- Start date
Passinwind
I know nothing.
- Dec 3, 2003
- 23,042
- 45,890
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
Hopefully that's true! I expect most of this is too niche for almost everyone, but the idea was too interesting for me to leave alone. Despite the amount of time it has taken, I am learning a tremendous amount along the way, and still find it entertaining.
I am still pretty new to this whole bass building thing, starting my first kit bass just over three years ago, but I pretty quickly (too quickly) decided that if I was going to invest enough time to make anything, I might as well jump straight to making things that would amaze me if I found it in a shop somewhere.
Unfortunately that immediately sets me up for failure, but if I do actually manage it then the sense of accomplishment will be worth it.
EDIT: there is nothing about this preamp that makes is bass specific. It would work equally well in a guitar or a bass.
That typo seems oddly apropos here, no?
Hah! I suppose that, compared to typical analog bass electronics, pretty much all of this would be considered heresy and witchcraft.
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Passinwind
I know nothing.
- Dec 3, 2003
- 23,042
- 45,890
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
I was thinking more of guitar players, who are seemingly often all about The Voodoo.
I think most guitar players would go running to find a crucifix to ward off a preamp with a computer in it!
On a totally different topic...
A couple of days ago, through some sequence of clicks I don't even remember, I landed on a video of Mark King playing World Machine. I probably hadn't heard that song in 30 years, but remembering that riff of 16ths part starting at 3:55:
got me thinking I should try to figure out how to play that song. The bass line is cool for sure, though I still can't play the 16ths part cleanly at full speed. As always, Mark makes it look easy, chewing gum, looking at the audience and singing while appearing to hardly raise a finger.
Anyway, all that got me to the Status Graphite site to check out some of those sweet carbon basses, and there I came across their price list. They offer triple color LEDs (versus millions of colors for programmable LEDs) as options, but the add-on price for the LEDs is truly eye watering: about $1,100 US. Made me pretty happy I was able to add those for an incremental cost of about $10!
On a totally different topic...
A couple of days ago, through some sequence of clicks I don't even remember, I landed on a video of Mark King playing World Machine. I probably hadn't heard that song in 30 years, but remembering that riff of 16ths part starting at 3:55:
got me thinking I should try to figure out how to play that song. The bass line is cool for sure, though I still can't play the 16ths part cleanly at full speed. As always, Mark makes it look easy, chewing gum, looking at the audience and singing while appearing to hardly raise a finger.
Anyway, all that got me to the Status Graphite site to check out some of those sweet carbon basses, and there I came across their price list. They offer triple color LEDs (versus millions of colors for programmable LEDs) as options, but the add-on price for the LEDs is truly eye watering: about $1,100 US. Made me pretty happy I was able to add those for an incremental cost of about $10!
Shipping is something I just don't understand. My order of 197 parts, including the elusive voltage regulators, just arrived:
Hooray! The strange part is that they spent 5 days making it from Grand Prairie, TX to Memphis, TN, and then just 17 hours making it from Memphis to Canada and on my doorstep.
Also in the order was this part:
...which I have never had occasion to put into a bass before!
Hooray! The strange part is that they spent 5 days making it from Grand Prairie, TX to Memphis, TN, and then just 17 hours making it from Memphis to Canada and on my doorstep.
Also in the order was this part:
...which I have never had occasion to put into a bass before!
Passinwind
I know nothing.
- Dec 3, 2003
- 23,042
- 45,890
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
I knew there was a reason I used a D-sub connector in this bass, that'd pop right in:
And yeah, deliveries from Mouser have been taking some pretty strange turns lately.
Holy moly!
The best part of that chart is that fully one-third of the 18 combinations result in the same slant single-coil pickup! Also notable is that none of those 18 combinations have any coil taps/series/parallel/phase combinations on any of the pickups!
The best part of that chart is that fully one-third of the 18 combinations result in the same slant single-coil pickup! Also notable is that none of those 18 combinations have any coil taps/series/parallel/phase combinations on any of the pickups!
If anyone is interested in some geekery, the natural tone preamp allows 900 unique pickup combinations, plus 4 level controls of 256 levels each, for another 4 billion (or so) combinations. Glad I don't have to draw a diagram showing all that!
Huh, that's really interesting. That setup looks like it's crosspoint switch based. There are still several things I am scratching my head about with their implementation, but it is amazing how many ways there are to solve the same problem.
Not surprising is that it was rather niche and never sold well. I'm sure the several thousand dollar (!) price tag didn't help.
One premise of the the natural tone preamp is the fact that series coils are additive because... physics, so 1+2 is the same as 2+1. In fact, I never built a user configurable combination for 2+1 because I considered it a duplicate. But at least one of the guitarists claims there is a difference. I kind of wonder if that's due to crosspoint switch limitations (crosstalk, capacitance etc.). Oh well, once I can start testing I will try reversing series order and see if I can hear a difference.
By far the biggest difference between this an the EBMM implementations is blending. Because the EBMM one is entirely passive they have no amplifiers and no ability to blend. Am I game changing a game changer here?
Wiring of the 2-coil prototype version of the preamp is done! Definitely a rats nest but hopefully functional:
I made some progress on my pickup mule build, though it still has a long way to go before it is ready for strings so I may just rewire my J-bass pickups to allow me to do some testing in the near term.
Unfortunately, I took a chunk out of the index finger on my plucking hand while building the neck for the mule so I may not be making a demo video as soon as hoped. I should be able to make enough bass noises to actually test out the preamp though, and if it goes well put in a PCB order and start testing the full circuit.
I made some progress on my pickup mule build, though it still has a long way to go before it is ready for strings so I may just rewire my J-bass pickups to allow me to do some testing in the near term.
Unfortunately, I took a chunk out of the index finger on my plucking hand while building the neck for the mule so I may not be making a demo video as soon as hoped. I should be able to make enough bass noises to actually test out the preamp though, and if it goes well put in a PCB order and start testing the full circuit.
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Success! Well, at least some success anyway. Because I didn't want to hand wire any more parts than necessary I only had one buffer amp and one mixer. That meant one pickup was un-amplified and was quieter than the other, but I could still successfully adjust the level of both of the pickups and rewire them from the command line, plus set the tone and master volume levels.
I did find one small problem on the schematic with reversal of the A and B pins of the master volume and tone pots, so level 0 was full and 255 was off. I could correct that in software but the right solution was to update the schematic and regenerate the traces, so I made that change. Oddly, running a DRC after the autorouter finished showed a single trace missing. Looking back at the ratsnest in the autorouter, it didn't include that connection. Hmmm... KiCad DSN export bug? Freerouter import bug? Not sure, but the DRC also found a few minor courtyard infringements and while I was making those adjustments I decided to add pads on each of the buffer amp inputs to allow for optionally adding a load resistor to any pickup if desired. Unfortunately, adding 4 more resistors on an already full board required a major component reorganization.
After spending most of an evening finishing the new board layout I ran it through the autorouter again. It churned overnight and after several thousand passes still had not finished all the traces. I think there simply wasn't enough board space left for everything to fit. Another hmmmm...
I decided to make a design change to remove the current limiting resistors on the mixer amp. Since the digipots are software controlled I can write code to make sure the pot wiper always has a minimum resistance to the A terminal, thus preventing shorting buffer amp outputs together during mixing.
Another schematic and board layout revision, and hand routing a few key components, and it was off to the autorouter again. This time it got close to finishing, but a few traces from the end got into a loop where it would undo and redo the same set of trace changes over and over, never completing. Sigh.
I could see some pinch points so tried moving a few components around to allow more space in some areas and set the autorouter to work again. This time it did complete, albeit with 154 (!) vias, so the board looked like it was made from swiss cheese. The optimizer ran for about 12 hours and got that down to down to 72 vias, and importantly, the DRC shows no traces missing. Hooray! Perhaps not as pretty as routing everything by hand (well, assuming someone with some skill was doing it!) but I was just glad not to have to do most of it myself!
PCBs are ordered and should be here in a month or so.
I did find one small problem on the schematic with reversal of the A and B pins of the master volume and tone pots, so level 0 was full and 255 was off. I could correct that in software but the right solution was to update the schematic and regenerate the traces, so I made that change. Oddly, running a DRC after the autorouter finished showed a single trace missing. Looking back at the ratsnest in the autorouter, it didn't include that connection. Hmmm... KiCad DSN export bug? Freerouter import bug? Not sure, but the DRC also found a few minor courtyard infringements and while I was making those adjustments I decided to add pads on each of the buffer amp inputs to allow for optionally adding a load resistor to any pickup if desired. Unfortunately, adding 4 more resistors on an already full board required a major component reorganization.
After spending most of an evening finishing the new board layout I ran it through the autorouter again. It churned overnight and after several thousand passes still had not finished all the traces. I think there simply wasn't enough board space left for everything to fit. Another hmmmm...
I decided to make a design change to remove the current limiting resistors on the mixer amp. Since the digipots are software controlled I can write code to make sure the pot wiper always has a minimum resistance to the A terminal, thus preventing shorting buffer amp outputs together during mixing.
Another schematic and board layout revision, and hand routing a few key components, and it was off to the autorouter again. This time it got close to finishing, but a few traces from the end got into a loop where it would undo and redo the same set of trace changes over and over, never completing. Sigh.
I could see some pinch points so tried moving a few components around to allow more space in some areas and set the autorouter to work again. This time it did complete, albeit with 154 (!) vias, so the board looked like it was made from swiss cheese. The optimizer ran for about 12 hours and got that down to down to 72 vias, and importantly, the DRC shows no traces missing. Hooray! Perhaps not as pretty as routing everything by hand (well, assuming someone with some skill was doing it!) but I was just glad not to have to do most of it myself!
PCBs are ordered and should be here in a month or so.
A bit more than a month later and these showed up today:
They look great, and I am excited to start wiring this up! First step will be to get the power supply components installed and tested to make sure none of the expensive silicon gets fried when running off battery and adding/removing phantom. Next add will be the microcontroller to confirm the digital stuff all works. Then all the remaining SMD stuff. I have plans to work on some necks as long as the weather is good, but the next rainy day the soldering iron will get fired up.
They look great, and I am excited to start wiring this up! First step will be to get the power supply components installed and tested to make sure none of the expensive silicon gets fried when running off battery and adding/removing phantom. Next add will be the microcontroller to confirm the digital stuff all works. Then all the remaining SMD stuff. I have plans to work on some necks as long as the weather is good, but the next rainy day the soldering iron will get fired up.
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Some small progress to report. Certainly not the prettiest soldering, but for my first time doing SMD I am glad that at least it is functional:
After some reading about how to make soldering SMD easier and ended up building myself one of those SMD beaks:
vpapanik: The SMD beak
I didn't have exactly those parts on hand so instead I used a piece of 3/4" copper pipe and a piece of 10 AWG copper wire. It was too light on its own so I added a lead weight I had on-hand from some old plumbing jobs and now parts are held down tight enough that they don't move with "gentle" soldering:
It all worked pretty well and let me get about a dozen parts down in about 30 minutes. It is clear the small discrete 1206 and SOT parts will take more time per-pin than the big SOICs so looking forward to getting the fiddly little parts done.
Unfortunately my SMD diodes are MIA. I know I had them a few months back but can't locate them anywhere now. I placed an order for some more but will need to wait for them to get here. Should be a week or two and will let me test the switching power supply once I get them.
After some reading about how to make soldering SMD easier and ended up building myself one of those SMD beaks:
vpapanik: The SMD beak
I didn't have exactly those parts on hand so instead I used a piece of 3/4" copper pipe and a piece of 10 AWG copper wire. It was too light on its own so I added a lead weight I had on-hand from some old plumbing jobs and now parts are held down tight enough that they don't move with "gentle" soldering:
It all worked pretty well and let me get about a dozen parts down in about 30 minutes. It is clear the small discrete 1206 and SOT parts will take more time per-pin than the big SOICs so looking forward to getting the fiddly little parts done.
Unfortunately my SMD diodes are MIA. I know I had them a few months back but can't locate them anywhere now. I placed an order for some more but will need to wait for them to get here. Should be a week or two and will let me test the switching power supply once I get them.
Freekmagnet
Commercial User
I’ve been tacitly following along on this project and actually was catching up this morning as I’ve been barely keeping up at all on TB.
But I had to comment on this video as a huge Mark King and Level 42 fan. They never cease to absolutely knock me out with just how friggin’ great they are! I’ve seen this and when I get home, I’m gonna look up some more from that concert. That Live at Lugano full show video just slays me every time. Their recent stuff is great, too, I just wish there was more of it!
I wish you continued success on this project!
