Heritage HRW pickups, basic data

[nuke]

I was just working on a semi-hollow body guitar, 2001 Heritage H535 (which is killer by the way) which has some unique pickups, Heritage HRW's.

I had it apart to clean some powdery corrosion off the bodies of the pots. (the plating on Bournes pots seems to do that, just cosmetic in this case). I did take basic measurements of the pickups, was running out of time and fishing all the electronics in and out of 335 style guitars is a chore. So didn't do the plot. The data didn't seem to suggest anything peculiar about the pickups.

The instrument wiring has 500k volumes and 250k tone pots, with .022 capacitors. The particular manufacturer tends to do this, rather than the more common use of same value pots. 

The other novel feature is the custom switch-tip, with the black dot. It is actually drilled and the black dot is inserted and cemented in place.

Only thing I might guess is Heritage bought the materials from Schaller, and wound them slightly over.

Also, Heritage only used these Bournes pots and values on HRW-equipped instruments, so pickups, harness and cool switch tip were a package deal. The pots appear to have a custom-taper, much smoother taper than most other volume/tone pots. Very usable taper and they have a good "feel". 

The HRW pickups were a significant upcharge as well, back in the day. This particular H535 also has very figured maple, top, back and sides, wooden pickguard. So, a really nice one. I swapped the Schaller roller bridge and tail for standard Nashville and stop bar, since I'm more used to that. 


Pics of the pickups, as you can see, they are made from Schaller components. 





Heritage HRW pickups by Rendal Wall, Heritage H535 2001:  

(built from Schaller base plates and components) 
The pickup basic data (humbucker, covered, PAF style)

HRW Neck:  
Screws North, 49-52 mt, alnico magnet slightly visible through a hole in the base plate. 
Brass baseplate, chrome plated cover, 4-wire harness with Schaller color codes. Short legs, double mounting screws. 
Neck position pole spacing, metric. 

Ls  4.35 H @ 100hz
Q  1.95 @1khz
Cp 112.54 pf @ 100khz
Cs 113.12 pf @ 100khz
DCR 7.498k at 68-degrees F


HRW Bridge:
Screws North, 55-62 mt, alnico magnet slightly visible through a hole in the base plate.
Brass baseplate, chrome plated cover, 4-wire harness with Schaller color codes. Short legs, double mounting screws.
Bridge position pole spacing, metric.

Ls  5.097 H @ 100hz
Q  2.08 @1khz
Cp 111.25 pf @100khz
Cs  112.44 pf @100khz
DCR  8.174k @ 68-degrees. 


Just for comparison, I have a Schaller humbucker from about the same era, Neck position

Schaller neck humbucker (no cover from factory)
Screws North, 50-55 mt  Alnico magnet visible.
Brass base plate, 4-wire harness,  standard screws/slug configuration

Ls 3.98 H @ 100hz
Q 2.06 @1khz
Cp 96.19pf @ 100khz
Cs 96.44pf @ 100khz
DCR 7.477k @ 68-degrees F


Given the measured values, I'm not expecting a lot of difference shown in a plot, versus the standard Schallers. I don't want to try to open them up, due to the large solder seam and that they're in fantastic condition and the guitar sounds really good just as it is.

[ms]

With 250K tone pots  the "ten" setting is the same as the half resistance setting when using 500K. (The corresponding number depends on the pot taper.)  I guess heritage wanted to keep the full treble tone a bit more mellow than normal.  This might also contribute to the smoothness of the control response that you noticed.

[nuke]

Yeah, I noodled around with another guitar with 500k a-taper tone pots, and 250k is roughly the same as setting the tone knob down to "8" instead of ten. 

The Bourns volume pot definitely has a nicer taper than most, it rolls off a good bit slower through the first 1/4 of rotation, which yields a very usable volume control if you want subtle. There are a number of similar "smooth" taper pots offered for guitars. I think the standard CTS audio taper rolls off a bit too fast. 

What is very interesting about the HRW pickups is the strength of the magnetic field.  The neck is 490-520 gauss, the bridge is reading a whopping 550 to 620 gauss!!! 

For comparison, the SD59's in another guitar made around the same time, read about 380-420 gauss on the neck, and 440-490 gauss on the bridge.  I checked a couple of other SD59 and JB pickkups, and comparatively less magnetic strength is present in the SD's (all with A5 magnets). 

The HRW has a shiny metallic magnet, a corner is visible through a hole in the base plate. So I think Rendal Wall was messing around with the magnetics more than the coils.  The electrical properties of the coils measure really close to other similar Schaller humbuckers from the same era.  

I don't think I've ever measured a humbucker with magnetic polepieces of this strength. 

[nienturi]

May 2, 2024 14:34:58 GMT -5 nuke said:

What is very interesting about the HRW pickups is the strength of the magnetic field.  The neck is 490-520 gauss, the bridge is reading a whopping 550 to 620 gauss!!! 

For comparison, the SD59's in another guitar made around the same time, read about 380-420 gauss on the neck, and 440-490 gauss on the bridge.  I checked a couple of other SD59 and JB pickkups, and comparatively less magnetic strength is present in the SD's (all with A5 magnets). 

The HRW has a shiny metallic magnet, a corner is visible through a hole in the base plate. So I think Rendal Wall was messing around with the magnetics more than the coils.  The electrical properties of the coils measure really close to other similar Schaller humbuckers from the same era.  

I don't think I've ever measured a humbucker with magnetic polepieces of this strength. 

Indeed they are too powerfull. I've read those values from the humbuckers with alnico 8 magnet within. Or ceramics.

[ms]

Well, whether or not they are too powerful or not depends on what you want.  I would expect them to be a bit brighter than  the usual humbucker, but this could be exactly what you need with the 250K tone pots.  The highs lost with the pots are not exactly as those gained with the magnets, and so he sound should be a bit different from other similar guitars.

[nuke]

Definitely alnico, like many other Schaller HB pickups. I can see a little of the magnet, shiny metal, not ferrite.  I don't know if it was grain-oriented A5, or A8.  I don't really want to open them up. The H535 sounds great, so just leave it be.