funkle

@Kinkh has threatened to build a pre based on the schematic but not sure if it will be in an external box, as this would negate the ‘per pickup’ filtering that would happen.

It’s fascinating. I guess the only way to know for sure is to build a ‘modern’ version of the circuit and see if it sounds similar. Perhaps though, @mhoss32or Nuno from Lusithand have basically done this already. Or the Underhill chap. With their own twists. I am interested to see that that circuit is apparently relatively even in the low end and low mids until you sweep the filter down there. That largely leaves the pickups, the neck, or the body, or a mix thereof, as the source for the low mid boost that Wals seem to enjoy. The neck should be ready soon…

I still plan to video the Lusithand preamp and get it on YouTube for your collective pleasure. Lots of personal stuff last few months which has gotten in the way. However I really want to also do a trial of @slowburnaz’s pickups with the John East Uni Pre system, to show what they sound like flat. I have one handy, just need to get to that as my next step after the Lusithand. The guy making the Wal clones (Octave Basses) comments on his FB page that he feels the Underhill preamp is similar in sound to the ACG EQ-01 and sounds good.

Well, I was today years old when I heard about the Underhill Bass Preamp, which has switchable modules, including a low pass filter module. https://www.underhillbass.com/about-4 The filter module page is here - https://www.underhillbass.com/copy-of-pd1-dual-preamp-1 No experience with it, but may be of interest to others looking at different makes of filter preamps. EDIT - found a review. https://www.talkbass.com/threads/review-underhill-dual-filter-onboard-preamp.1564526/

Yes, BC549 NPN transistors and a TAB1043 Programmable Quad Op Amp. People have attempted to try and find a suitable replacement. https://music-electronics-forum.com/forum/music-electronics/16236-looking-for-an-alternative-to-tab1043-ic. There seems to be debate elsewhere about whether the op amp makes much odds to the sound or not. Newer Wals appear to keep the same op amp. https://www.talkbass.com/threads/desparately-trying-to-recreate-wal-tone-club.1162886/page-3#post-17987143. The implication might be that it is indeed part of 'the sound'.

Beautiful!! Almost a roasted look, I love that. I can’t wait to hear if it makes a difference to the sound of the build, as I hope. @Bass Culture’s build was fascinating to see and the sound clips/videos he did recently were interesting to me. Mainly because I still thought the sound he got out of his Wal clone was cleaner/less low mid heavy than I expected, even with all of the attention to Wal-like detail. (Sounds great BTW) This raises the possibility again of the sound mostly being the pickups/preamp, as alluded to by many on this thread. Alan @skelfwas clear to me that he thought the Wal sound mostly was in the preamp. I guess this is how R&D goes. At least I can share what I find publicly…my successes and failures… The chaps working back a Wal Custom preamp schematic from my photos tell me the topology is different to what has been generally thought. I quote them directly from a recent message: ’The thing that struck me the most was the filter topology used in the original. Most people on the net assume that the Wal uses a "state variable filter" topology. This type of filter is a bit more complicated (more components), but can easily change cut off frequency and Q factor (boost at the cutt off freq) independent of each other. From what I can see, the original uses a Sallen-Key topology - which isn't that flexible at all. It has fewer components, but gain, freq and Q can't really be adjusted independently, maybe to a degree and with some wild twists. And the original Wal is using all those wild twists. The Attack function is also very interesting - a signal is taken from one of the pickups (I think it's the bridge pickup) and passed through a high pass filter, leaving only the high end of the raw pickup signal. Then later at the end of the signal chain, that signal is added to the total mix for the attack effect. Really clever idea!!!’ I briefly note in passing Alan’s use of a similar idea for adding treble back in for the ACG EQ-01. Though his lets you pick which pickup to take the signal from. I attach a draft very early version of a preamp schematic, though without values or second pickup yet added, for your pleasure.

Just bought Steve's Godin Shifter bass, a pleasure to deal with, easy communications and quick postage. What more can you ask for? Thanks Steve. Pete

Ryan bought my Sadowsky MV4E. Completely straightforward deal, easy communications. Thanks Ryan! You can deal with him in good confidence.

True. Even so…Jazzes sound like Jazzes in my hands, Precisions sound like Precisions…etc. There are variations within the type, but the type is characteristic.

I agree the player is the most important part. I spent 6 months working daily on right hand technique and it helped my sound a lot. That said. Now I know what a Wal sounds like in my hands. So I kind of know what I want to aim for.

Lol, of course! 😄

Great sounding clips @eude! Got to say, those clips sound solid, sounds to me like the ACG DFP and the ACG multicoil pickups can do a great job of the Wal BSSM sound. I can hear you hitting the bass harder and it sounds right for Flea's tone to me. Cleaner than the Wal/Lusithand preamp too. It may not have quite the built in low mid push of the Wal, but I'd bet it is a good bit more flexible overall. The Uber spec of Alan's basses is expensive, but it sounds great. I think it's £3k upwards for that spec of bass? Might be a good deal for some folks....

FYI, a friend on Talkbass has finished tracing out the Wal preamp circuit. It’s not yet clear if the photos I supplied gave enough detail for all the resistors to be correctly identified, but he was going to test it out anyway in software and see if how it acted looked reasonable or not. I hope to be able to provide accurate schematics at some point in the near future.

I have never liked the look of multilaminate headstocks. One of the things I like about some Yamahas, for example, is that they cover it up. Same for many Warwicks. @LukeFRC it’s more about aesthetic than strength.

Andy, I will also sort out the check of neck profile for you as well. I’ve been slack.

Really interesting, thanks for that. Your inventiveness has been incredible to watch. I am really interested in buying one of these to test out. I love the tweakability and the pick attack, although I would lower the frequency range to the Wal type range myself. 80Hz catches that first harmonic of E and I like the ability to use one pickup for ‘bass’ and the other for mids emphasis, adding in the pick attack to taste. Equally doing both pickups as ‘bass boost’ and activating pick attack allows for the modern scooped sound as you say. Can I ask. There is something about the Lusithand that adds a little grit to the tone; the ACG EQ-01 design lacks this though is marvellously flexible. I assume the Lusithand must add a minor amount of harmonic distortion which is pleasing to the ear. The Wal does this also. Does your own system tend to the ‘cleaner’ side, or do you think it adds something more like the Lusithand and Wal preamps do?

I am fascinated by your frequency range choices. You’re not far off what Nuno at Lusithand came up with, though my quibble with his pre is that it lacks the bright switch of the Wal/your preamp, which I think is important. I’m interested that you did not extend down into the bass range, but stuck to mids up to the low treble region. Can I ask your thoughts behind that? (I have felt that going down to 80-100Hz to be quite useful, but would like to hear your experience).