Pickup transplant

[bobmeyrick]

A few years ago I replaced the Gibson "The Original" HBL and HBR pickups (the "circuit board" pickups) and wiring harness in my '89 ES335 Dot Reissue with a pair of Seth Lovers and some new pots, caps and switch, with a resulting improvement in tone. Recently I'd been thinking about replacing the Schallers in my Trans Black H150, and it occurred to me that I had these "Originals" lying around. Unsoldering the pickups from the harness, I measured their DC resistances - 7.3k for the HBR (neck) and 8.9k for the HBL (bridge). After a bit of research on the web, it seems they have Alnico 5 magnets and are either loved or hated. Hmm...

I installed them in the H150 and they sounded fine, not unlike the SD 59s in another of my H150s, with a touch more mid-range. They had more clarity than I remembered when they were in the 335, which set me thinking... I measured the volume pots on the original harness from the 335, and what do you know, one was 300k (bridge) and the other 100k (neck)! The H150 already has 500k pots, which explains why the pickups sound better. Remember that Doug and Pat Show video (Shootout #2), where they found that changing from 250k to 500k pots opened up the guitar?

I wonder if the reason the "Originals" are disliked is that they've been paired with pots with too low a resistance.

[rockabilly69]

1 hour ago, bobmeyrick said:

A few years ago I replaced the Gibson "The Original" HBL and HBR pickups (the "circuit board" pickups) and wiring harness in my '89 ES335 Dot Reissue with a pair of Seth Lovers and some new pots, caps and switch, with a resulting improvement in tone. Recently I'd been thinking about replacing the Schallers in my Trans Black H150, and it occurred to me that I had these "Originals" lying around. Unsoldering the pickups from the harness, I measured their DC resistances - 7.3k for the HBR (neck) and 8.9k for the HBL (bridge). After a bit of research on the web, it seems they have Alnico 5 magnets and are either loved or hated. Hmm...

I installed them in the H150 and they sounded fine, not unlike the SD 59s in another of my H150s, with a touch more mid-range. They had more clarity than I remembered when they were in the 335, which set me thinking... I measured the volume pots on the original harness from the 335, and what do you know, one was 300k (bridge) and the other 100k (neck)! The H150 already has 500k pots, which explains why the pickups sound better. Remember that Doug and Pat Show video (Shootout #2), where they found that changing from 250k to 500k pots opened up the guitar?

I wonder if the reason the "Originals" are disliked is that they've been paired with pots with too low a resistance.

Yep it's a pretty well known fact that Gibson choked their pickups with those 300K pots, but i've never heard pf them using a 100K pot. That sounds like a defective pot.

[cobo]

2 hours ago, rockabilly69 said:

Yep it's a pretty well known fact that Gibson choked their pickups with those 300K pots, but i've never heard pf them using a 100K pot. That sounds like a defective pot.

Agree, 100k, if it was truly in the full clockwise (or counterclockwise) position is unheard of. Are there different markings on the back of pots that would indicate they should measure so differently?

 

Also, increasing the volume (or tone) pot impedance would generally boost the signal you hear. Louder always sounds “better” and/or makes it easier to hear details, and that increased value in the tone pot would definitely make the pickups sound brighter, so I think the original poster is spot on in thinking the higher impedance pots provided more “clarity”. 

[bobmeyrick]

2 hours ago, cobo said:

Agree, 100k, if it was truly in the full clockwise (or counterclockwise) position is unheard of. Are there different markings on the back of pots that would indicate they should measure so differently?

I measured across the end terminals of the pot, i.e. across the whole track. Interestingly a bit of searching revealed that Gibson apparently sometimes used 100k tone pots in the '70s and '80s, so perhaps the wrong pot was used when the guitar was initially wired up.

[davesultra]

I had a '79 LP Custom back in 1991. It had 100k tone pots stock. Gibson had been known to use them.

[rockabilly69]

I stand corrected, I was never aware of the 100K pots! I just checked and some people have reported them being used from 1977 to 1980. But the OPs guitar is a 1989! I have a Gibson L5s from 1978 I will check the tone pots to see what they used there! And I can just imagine hot a dark a 100K tone vol pot is with a neck pickup! I always put the highest K pot in a set on the neck vol!

[High Flying Bird]

Some detective work going on here.  What a cool forum.

[bobmeyrick]

I just re-measured the resistance of that "100k" pot, and it now reads 527k. D'Oh! Not sure how that happened... I can only put it down to my own incompetence. Also looking again at the  arrangement of the wiring, that pot was for the bridge pickup. All the other pots are around 300k. Here's a picture of the wiring harness...

You'll notice that the bridge volume pot is different from the others. I was slight puzzled by this, then I remembered that many years ago (I've had the 335 since the early '90s) I had a problem with the bridge pickup sounding weak. My repair man fixed it, presumably because the original pot had developed a fault and was consequently replaced with a 500k pot.

What can we learn from this? Well,

• Gibson in the '80s used 300k pots which didn't do the pickups any favours.
• Gibson "The Original" HBL and HBR pickups may not be as bad as some people say they are.
• I need to take more care when measuring resistances.
• It's much easier to change the pickups on an H150 than it is on a 335...