Don’t know about the standard Eppi IV caps or Pups.
The Goth pups are wound heavy with a resistance of up around 14.5K for both the bridge and neck. They also have a high value tone cap of .068uf with 500k pots. Installing a .022uf tone cap in the Goth completely transformed the bass. It really opened up the tone palette and drastically increased the volume level. It basically lets the pups breath vs choking them down.
Pre cap change, I’d run the volume around 7 and the tone at about 5. After the change I’m running the volume around 3 and the tone at about 1. If I take the volume up to 7 or 8 those hot pickups tear the house apart.
Here’s a flashback to the original testing from 2020…
Just wrapped up the first leg of the Goth tone cap and pot test where the 500K pots were in the control circuit.
Keep in mind this test was done with fresh Cobalt Flats and stock Goth pups. String or pup changes could give different results. I also limited the tests to finger playing only, between the neck and the neck pup with the neck pup soloed. No adjustments were made to the amp, everything centered.
The first run through was wired with a specific cap and the tone pot set at zero and the volume knob at two, followed by volume settings of 4,6,8,10 with notes taken at each volume setting.
The second run was the same cap with tone set at 3 and volumes at 2,4,6,8,10.
The third run was the cap with tone set at 5 and volumes at 2,4,6,8,10.
That's 15 data points for each cap.
I didn't bother to record data above a 5 setting on the tone pot because I found no significant change in tone with any tested cap above that setting. I eliminated a few caps in pre-testing, the 1.0 cap ended up being nothing more than an off/on switch. At a tone setting of zero there was no signal to the amp, great if you want a mute switch, settings above that were deep and dark but resulted in very little tone change regardless of the setting. I eliminated the caps with values less than .022uf because they seemed to have very little impact on tone, it was nearly the equivalent of hardwiring the pups to the output jack.
The caps that were tested were .001, .082, .068, .047 and .022 (my apologies to those of you who use commas in place of decimal points, I'm sticking to the American standard on this one).
Findings were different than I anticipated but did highlight a huge interplay between the volume and tone knobs. Some of the caps that sounded best at a given volume were completely unuseable at other volumes. And louder is better doesn't always hold true.
Findings:
.082uf cap - smooth, deep and dark, nice low mids BUT very little adjustability. A tone knob setting of zero requires a volume knob setting of 8 to get any useable level of sound, and at a volume setting of 9 or higher it sounds very harsh and unpleasant (my notes actually say "yuck"). This is the cap that I thought would sound best, so much for confirmation bias. Kick the tone knob up to 5 and you have nice smooth useable lows starting at a volume setting of 4 to 6. At a volume of 8 the high mids start to kick in and quickly ruin the party. Bottom line - not ready for prime time.
.068uf cap - this is what the Goth comes stock with. Unfortunately my stock cap got fried in the desolder so I had to wire a couple of orange caps together for a .069uf value, close enough. Good deep tone, a bit muddy at the low tone settings and moving to more mid focused as the tone pot value is increased. Loud and boomy at volume settings of 9 or higher. Sweet spot on the volume knob is between 4 and 8. Below that and not enough useable volume, above that it's boomy and undefined. Bottom line - ok but could be a lot better.
.047uf cap - I found this one surprising. At zero tone it's much to quiet until you get the volume knob up to about 7 or 8. At that point it sounds great, but then takes a massive volume jump when the volume knob hits 9 and sounds harsh as it's maxed. The good news is it takes on a different personality when the tone knob is set at 3. Sounds very nice and balanced, smooth, deep but defined at volumes of 2 to 8 very linear and predictable, then falls apart again at a volume of 9 or higher when an upper mid hump sets in. If the tone knob is set at 5 the mids kick in much sooner and sound nice until you hit a volume setting of 8 or higher. Bottom line - I could live with this one. Lots of useable tones once you get off the zero tone setting.
.022uf cap - not what I expected at all. At zero tone setting it was very smooth and balanced across all strings. At a tone setting of 3 it had very musical lows and low mids, very useable tone at volumes of 3 or higher. At a volume of 9 still quite nice. Volume maxed at 10 brought out the yuck factor with an almost overdriven distortion boomy obnoxious sound. But again, a picture perfect sound from volume settings of 3 to 8 and tone settings of zero to max. bottom line - this is the keeper cap of the bunch for the 500K pots. Will be interesting to see how it works with the 250K pots.
.001uf cap - tone on zero gives super loud deep lows even at volume settings as low as 4, thunderous at a volume of 6, destructive at 8, then at a volume of 9 the upper mids mix in and you better have hearing protection and a spare set of speakers for your cab. Increasing the tone cap setting drastically increases mids. On this bass this is the cap to use if all you want is lows and low mids and don't mind leaving the tone pot on zero and the volume at 5 or less. Truly makes a one trick pony (or wrecking ball) out of the Goth. Bottom line - "nuke em from orbit"
And there you have it (well, half of it, the other half will happen when the 250k tone pot arrives).
TB rules, pic or it didn't happen...
Note: the cap labeled .1 in the pic is actually a .001uf cap
