Building a Wal....ish

[LukeFRC]

1 hour ago, NickA said:

Did Wal deliberately degrade the sound path to get a more "organic" sound or is it just a happy accident? !!  Who knows. 

It would be hard these days to find a IC with as low slew rate and supposedly “bad” performance as the one they use. 

[HotelX]

Is there consensus in which filter-based preamp is the best, or are they all good yet slightly different?
 

Also a related question, how is the power consumption on them? Are they all fairly power efficient?

[slowburnaz]

6 hours ago, LukeFRC said:

It would be hard these days to find a IC with as low slew rate and supposedly “bad” performance as the one they use. 

Makes you wonder what Wal does currently…

 

Do they have huge stash of those in a secret vault somewhere? 🙂

[NickA]

1 hour ago, HotelX said:

Is there consensus in which filter-based preamp is the best,

Depends what you want!  The John East ones are very clean, but clip horribly if overdriven with a less than full voltage battery. Alembic also quite HiFi.  Lusithand, we're told, a little gnarlier.  The Wal one "distinctive" in it's soft distortion .. roughs up beautifully if you play hard. 

 

I play my Wals a lot and hardly ever change the batteries... The bass with the East ACG in it once went flat mid rehearsal .. but maybe the battery was duff.  My own version less good as it derived a split +-4.5V supply voltage from a potential divider ... which used more power than the 8x op-amps!

 

As for function, all have a low pass filter for each pickup, a pickup blend and a master volume.  Filters different tho. Wal and Alembic have filter Q switches ( boosts at the cut frequency).  The East acg-eq-01 has variable Q filters ( two extra pots).  Wal and the East have a "bright boost" /"pick attack" function; switched in the Wal, variable in gain and frequency on the East ( yet another two pots!) 

 

The East has the most tweakability ( too much ..hence newer versions only available on ACG basses).  The Wal one is most organic.  Choices choices.

[funkle]

15 minutes ago, slowburnaz said:

Makes you wonder what Wal does currently…

 

Do they have huge stash of those in a secret vault somewhere? 🙂

Yes, I think they do have a huge stash. 

 

1 hour ago, HotelX said:

Is there consensus in which filter-based preamp is the best, or are they all good yet slightly different?
 

Also a related question, how is the power consumption on them? Are they all fairly power efficient?

I don’t think there’s a full consensus yet. My take is:

 

The ACG is for a clean and clear sound which allows a ton of adjustability, including control of treble boost/brightness. Seemed power efficient to me when I used it. 

 

The Lusithand gives grit and allows mainly mid control, though Nuno is going to change the EQ range on the front pickup to go down to 100Hz, but it has no bright switch. Also seemed power efficient. 

 

The Underhill I have no experience of but actually seems to give some grit I wasn’t expecting in sound clips and has a good deal of adjustability, including an adjustable bright switch. It sounds viable in a Wal project to me. No idea on power efficiency. 
 

The final pre is the mystery maker clone pre I have, which is a modern clone of the Wal preamp, based on the schematics in this thread. I will report on how it sounds as soon as I can, and will comment on power then as well. 

[LukeFRC]

29 minutes ago, slowburnaz said:

Makes you wonder what Wal does currently…

 

Do they have huge stash of those in a secret vault somewhere? 🙂

Everyone says it’s inflation but the price of Wals only went up when they had to buy their own chip factory in Taiwan 

[luthifer]

30 minutes ago, funkle said:

Yes, I think they do have a huge stash. 

 

I don’t think there’s a full consensus yet. My take is:

 

The ACG is for a clean and clear sound which allows a ton of adjustability, including control of treble boost/brightness. Seemed power efficient to me when I used it. 

 

The Lusithand gives grit and allows mainly mid control, though Nuno is going to change the EQ range on the front pickup to go down to 100Hz, but it has no bright switch. Also seemed power efficient. 

 

The Underhill I have no experience of but actually seems to give some grit I wasn’t expecting in sound clips and has a good deal of adjustability, including an adjustable bright switch. It sounds viable in a Wal project to me. No idea on power efficiency. 
 

The final pre is the mystery maker clone pre I have, which is a modern clone of the Wal preamp, based on the schematics in this thread. I will report on how it sounds as soon as I can, and will comment on power then as well. 

In a Wal configuration with two switched filters (one, two, or three Q level switchable) and the pick attack filter, the Underhill draws 3.3 mA. The power drain of all the modules is on the web site.

[slowburnaz]

49 minutes ago, funkle said:

Yes, I think they do have a huge stash. 

 

I don’t think there’s a full consensus yet. My take is:

 

The ACG is for a clean and clear sound which allows a ton of adjustability, including control of treble boost/brightness. Seemed power efficient to me when I used it. 

 

The Lusithand gives grit and allows mainly mid control, though Nuno is going to change the EQ range on the front pickup to go down to 100Hz, but it has no bright switch. Also seemed power efficient. 

 

The Underhill I have no experience of but actually seems to give some grit I wasn’t expecting in sound clips and has a good deal of adjustability, including an adjustable bright switch. It sounds viable in a Wal project to me. No idea on power efficiency. 
 

The final pre is the mystery maker clone pre I have, which is a modern clone of the Wal preamp, based on the schematics in this thread. I will report on how it sounds as soon as I can, and will comment on power then as well. 

Some of the grit from the clip I made with the Underhill could partially be coming from the amp simulation.  I listed the signal path in the description of the clip on SoundCloud, but essentially it’s this:

Bass -> Axe I/O Solo -> Amplitube 4 Bass 1 Complete Rig (all defaults) -> T-Racks 5 White 2A Compressor w/ gain dialed down a bit from default to 30

 

I typically record clips with this simple setup to give a more “realistic” example of how things will sound for most players who will most likely be running through an amp of some sort.

 

If anyone’s interested, I can also post a similar sample with the amp sim stuff disabled and only the compression on.

[funkle]

Ah, that could explain the grit I was hearing. @luthifer is your system designed to have harmonic distortion, or is it cleaner a la the ACG? 

[slowburnaz]

I just recorded this without the amp sim stuff...  just a little compression:  https://on.soundcloud.com/TJULR

 

I tend to play with a pretty heavy hand, too.

Edited April 10, 2023 by slowburnaz

[funkle]

Thanks Chris. I think you’re still getting some kind of grit from the compression, either that or there is some in that circuit as well. I guess @luthifer might be the most sensible person to comment…

[luthifer]

50 minutes ago, funkle said:

Ah, that could explain the grit I was hearing. @luthifer is your system designed to have harmonic distortion, or is it cleaner a la the ACG? 

It is very clean. The variable Q filter uses a circuit that is much quieter at full Q (and has very linear Q control - 1/2 way is 1/2 way - and base gain is dead on), but has the downside of clipping at roughly the level of 350mV with 7V supply (and max Q). With a fresh battery, gain trimmers only used to balance pickups, and normal output pickups, it won't clip. But high output pups may need more than 9V.

 

The sample is with the variable Q filter (The switched Q filter has a lot more headroom). I think it may be clipping a bit (hard to tell) but it doesn't sound harsh. Sounds pretty good, actually!  The gain trimmers are applied before the filter, so if you wanted some distortion intentionally, you could crank them up and get it for sure. The high gain is available so you can use the preamp by itself as a booster, but it can definitely overdrive the variable filter, which has internal gain above the gain coming out.

Edited April 10, 2023 by luthifer

[Passinwind]

15 hours ago, luthifer said:

It is very clean. The variable Q filter uses a circuit that is much quieter at full Q (and has very linear Q control - 1/2 way is 1/2 way - and base gain is dead on), but has the downside of clipping at roughly the level of 350mV with 7V supply (and max Q). With a fresh battery, gain trimmers only used to balance pickups, and normal output pickups, it won't clip. But high output pups may need more than 9V.

 

The sample is with the variable Q filter (The switched Q filter has a lot more headroom). I think it may be clipping a bit (hard to tell) but it doesn't sound harsh. Sounds pretty good, actually!  The gain trimmers are applied before the filter, so if you wanted some distortion intentionally, you could crank them up and get it for sure. The high gain is available so you can use the preamp by itself as a booster, but it can definitely overdrive the variable filter, which has internal gain above the gain coming out.

Nice to see you on here! And all of that sounds pretty familiar...😎

[luthifer]

5 hours ago, Passinwind said:

Nice to see you on here! And all of that sounds pretty familiar...😎

Hi Charlie! Yes, tradeoffs and design decisions... By the way, folks, Passinwind is the guy who sucked me into this rabbit hole! I don't know whether to love or hate him!

[NickA]

6 hours ago, Passinwind said:

I think it may be clipping a bit (hard to tell) but it doesn't sound harsh.

Get a 'scope on it! 

 

My homeade "Wal" 'tronics clipped when I tried playing slap; the sound of a nice slap twang is somewhat different from the sound of a squared off waveform .. but my picoscope showed the truth.  Needed to go 18V or attenuate the pickup signal ... or just buy an ACG-eq-01 🙂 ... which handles the peak signal fine (high pickup attenuation followed by high gain I guess). 

[luthifer]

12 minutes ago, NickA said:

Get a 'scope on it! 

 

My homeade "Wal" 'tronics clipped when I tried playing slap; the sound of a nice slap twang is somewhat different from the sound of a squared off waveform .. but my picoscope showed the truth.  Needed to go 18V or attenuate the pickup signal ... or just buy an ACG-eq-01 🙂 ... which handles the peak signal fine (high pickup attenuation followed by high gain I guess). 

I don't think Slowburnaz has a scope. Yeah I've measured well over a volt on the scope with slap! Slap is y'ur low battery indicator   That's exactly what the EQ-01 does. I don't like the noise at high Q (or the Q control curve), but for super aggressive playing or "one size fits all" it's a great choice.

[luthifer]

On 07/04/2023 at 10:26, Passinwind said:

 

 

I can take a stab at doing a better one later, but at least it's mostly readable now.

So I'm pretty sure C24 and C25 are supposed to be 10n.  Even with the gain of the inverting "attack" amp all the way up (2x), you would barely hear the boost at frequencies below 7 or 8 kHz. 10n caps there would bring the cutoff frequency down around 500 Hz, which gives you lots of boost around the 1-2k "pick" frequencies and above. Maybe I'm missing something; what happens with the OUTB signal before it hits the final mixing amp is very confusing without a clearer picture.

 

[Passinwind]

16 hours ago, luthifer said:

So I'm pretty sure C24 and C25 are supposed to be 10n.  Even with the gain of the inverting "attack" amp all the way up (2x), you would barely hear the boost at frequencies below 7 or 8 kHz. 10n caps there would bring the cutoff frequency down around 500 Hz, which gives you lots of boost around the 1-2k "pick" frequencies and above. Maybe I'm missing something; what happens with the OUTB signal before it hits the final mixing amp is very confusing without a clearer picture.

 

I haven't done up a Spice model of this yet, as I have a lot of customer work going on at the moment. Thanks for the heads-up!

[funkle]

19 hours ago, luthifer said:

So I'm pretty sure C24 and C25 are supposed to be 10n.  Even with the gain of the inverting "attack" amp all the way up (2x), you would barely hear the boost at frequencies below 7 or 8 kHz. 10n caps there would bring the cutoff frequency down around 500 Hz, which gives you lots of boost around the 1-2k "pick" frequencies and above. Maybe I'm missing something; what happens with the OUTB signal before it hits the final mixing amp is very confusing without a clearer picture.

 

According to the chap who drew up that particular schematic, it looks those are indeed 1n - they are clearly labelled - see this reference photo:

 

 

Sorry to be the bearer of bad news. 

[NickA]

I put a spectrum analyser on my fretless and reckoned the boost was around 6kHz ... coinciding with my maximum hearing loss!!   Which is why I hooked up the analyser to see if it was working 😁

[luthifer]

5 hours ago, NickA said:

I put a spectrum analyser on my fretless and reckoned the boost was around 6kHz ... coinciding with my maximum hearing loss!!   Which is why I hooked up the analyser to see if it was working 😁

Wow! That's as I suspected if the caps are 1n. I'm surprised the pick attack is up that high. Yeah I can't hardly hear it either. Nor can my bass amp when set flat!

[luthifer]

5 hours ago, funkle said:

According to the chap who drew up that particular schematic, it looks those are indeed 1n - they are clearly labelled - see this reference photo:

 

 

Sorry to be the bearer of bad news. 

Not bad news, just surprising they want to boost way up there. I spent enormous amounts of time playing with a pick and trying different frequencies to get the same kind of meaty pick sound, and settled on ~2k. 6k seems more like a "fret noise" boost to me...

[LukeFRC]

Glockenklang on board preamp has the treble control at 18k or something- so it being higher isn’t completely crazy. 
 

[Kiwi]

15 minutes ago, LukeFRC said:

Glockenklang on board preamp has the treble control at 18k or something- so it being higher isn’t completely crazy. 

Given the absolute limit is 20Khz...and that decreases with age...it doesn't clarify much unless the bandwidth is huge.

[funkle]

5 hours ago, luthifer said:

Not bad news, just surprising they want to boost way up there. I spent enormous amounts of time playing with a pick and trying different frequencies to get the same kind of meaty pick sound, and settled on ~2k. 6k seems more like a "fret noise" boost to me...

A lot will depend upon the cabinet/crossover design. I use an FRFR cabinet with plenty of treble response available and get a lot of ‘air’/‘sparkle’ with the Wal treble boost. I sometimes use the bright switch on the Berg B-Amp around 7k or so for a similar effect. It’s a ‘Miller-iser’ switch.