GFS Boston Blues, Analysis and Review

[antigua]

www.guitarfetish.com/Boston-Blues-Alnico-Strat-Pickup-Set-Vintage-Wound-SUPER-blues-Power_p_140.html

I just bought a this set, because it had the output level I was looking for, and the coils are blue! How neat is that?

I haven't installed them yet, so this first post is just an analysis of their physical properties, which is useful for comparisons to other pickups for which there exists similar measurements.

If anyone has tried these pickups out, I'd love to hear what you think about them.



GFS Boston Blues Bridge
DC R: 6.21K
L: 2.807 H
Q: 2.274
Peak: 10.0 kHz
Calculated C: 90pF
Coil width: 0.565"

GFS Boston Blues Middle
DC R: 5.72K
L: 2.489 H
Q: 2.160
Peak: 10.5 kHz
Calculated C: 91pF
Coil width: 0.565"

GFS Boston Blues Neck
DC R: 5.57K
L: 2.320 H
Q: 2.038
Peak: 11.4 kHz
Calculated C: 84pF
Coil width: 0.565"


The set features AlNiCo 5 poles pieces. Gauss readings on the poles was between 900 and 1100.

The only interesting thing I see in the specs off the bat is a relatively low capacitance and low Q, I predict they will sound decent enough in the guitar.



Here is a "loaded" plot, with 200k and 470pF C across each pickup:



Special thanks to Ken Willmott kenwillmott.com/ for designing the integrator used for the measurements.

[reTrEaD]

I noticed you measure all pickups with a 200k load. That makes sense with HBs. For single-coil pickups, especially those we would expect to see as replacements in a Strat or Tele, I would think 100~115k would be more appropriate?

[stratotarts]

Sept 27, 2016 10:04:14 GMT -5 reTrEaD said:

I noticed you measure all pickups with a 200k load. That makes sense with HBs. For single-coil pickups, especially those we would expect to see as replacements in a Strat or Tele, I would think 100~115k would be more appropriate?

There was a discussion that led up to the adoption of 200k on strat-talk. JohnDH posted the most succinct explanation:

"1.Humbuckers commonly use two x500k pots, which with 1M amp input, equates to 200k

2. Singles, also often see a single 250k pot plus amp input (ie the same as 1), based on bridge positions on Strats, either classic wiring (no B tone), or modern Am Standard with a no-load tone pot.

3. This loaded point, while it needs to be significantly away from the unloaded tests, reveals information about the pickup more sensitively with less load, than if you match with say 2x250k pots plus amp input. With many pickups, if you model them with 2x250k pots plus 1M = 111k, or thereabouts, the resonant peak is largely killed off, making the data much less useful."

[antigua]

Sept 27, 2016 10:04:14 GMT -5 reTrEaD said:

I noticed you measure all pickups with a 200k load. That makes sense with HBs. For single-coil pickups, especially those we would expect to see as replacements in a Strat or Tele, I would think 100~115k would be more appropriate?

There's a funny story here. John H, stratotarts and myself were discussing dummy load values here www.strat-talk.com/threads/measured-electrical-differences-between-a-fat-50-and-a-texas-special.390958/page-33 , and so the reasoning behind those values is discussed there. Then John H noticed later on that Helmuth Lemme used the same dummy load values here, 200k and 470pF, www.planetz.com/wp-content/uploads/2014/10/Pickup_Measuring_Technique.pdf , but for different reasons. 

I agree with you for the most part, but it's easy enough to assume that in the case of an actual Strat, you will see a diminished Q factor, perhaps a -2dB to -3dB drop at the resonance (potentially causing it to disappear), and in a Les Paul, you'd perhaps see a +2dB increase. It's kind of interesting when you consider that Strat pickups have such a high Q factor due to the utter lack of eddy current losses, and then guitarists use 250k pots to basically cause similar losses. It suggests that a high Q factor is not such a prized quality, and that guitarists are looking for a softer knee at the peak.

If you know the inductance, and total capacitance (probe included), it's possible to calculate the resonant peak for any load. Since we have that data, we can back fill it later, if we want. It's also possible to do comparative modeling, either with a circuit simulator like LTSpice, or John H's GuitarFreak dynamic spreadsheet, that will even model the eddy current losses, so just about anything you'd want to know can be calculated or visualized with the data and tools at hand.  

[JohnH]

Sept 27, 2016 11:38:47 GMT -5 stratotarts said:

Sept 27, 2016 10:04:14 GMT -5 reTrEaD said:

I noticed you measure all pickups with a 200k load. That makes sense with HBs. For single-coil pickups, especially those we would expect to see as replacements in a Strat or Tele, I would think 100~115k would be more appropriate?

There was a discussion that led up to the adoption of 200k on strat-talk. JohnDH posted the most succinct explanation:

"1.Humbuckers commonly use two x500k pots, which with 1M amp input, equates to 200k

2. Singles, also often see a single 250k pot plus amp input (ie the same as 1), based on bridge positions on Strats, either classic wiring (no B tone), or modern Am Standard with a no-load tone pot.

3. This loaded point, while it needs to be significantly away from the unloaded tests, reveals information about the pickup more sensitively with less load, than if you match with say 2x250k pots plus amp input. With many pickups, if you model them with 2x250k pots plus 1M = 111k, or thereabouts, the resonant peak is largely killed off, making the data much less useful."

Yes this!

The tests presented here are a careful balance of several intentions:

1. Having a consistent set up so that results can be compared to each other or between different experinenters.
2. Getting the maximum useful data out of just two tests and some meter readings.
3. Having results that can either be used just to directly view without needing any theory, or
4. To go deeper and use them to predict performance in any different circuit.

Lots more to write about all that. But I have a daft mental analogy about this that helps when Im working out equivalent models for use in GuitarFreak. It goes like this:

There is treasure in the north-west corner of Farmer Jones's field and I want to draw a map so I can find it (represents a tonal result that Im seeking). I want to know where his field is and which direction is north.

I can read the equivalent of manufacturers pickup specs and find out the the farm is 35 miles from London or that it is east of Salisbury. I haven't found the treasure yet.

I can go to the equivalent of Antiguas loaded data and find an exact point in the centre of the field. I know I am close but I dont yet know how to orientate my map or where to head.

So I also use the equivalent of the unloaded test. This is a distant point, that I dont actually want to go to, but I can see it on the horizon and it allows me to correctly orientate my map. I can now use it to find any point in the field quite accurately.

So the idea is (back to the pickups), we have one load point that is close to representing real use, even if not exact for every case, and another that represents a distant load point. This allows models to be derived that track along a reasonably correct course for different loads.

/rambling analogy

[reTrEaD]

Hello stratotarts,

I've seen your name previously mentioned along with antigua's in John's Guitar Freak thread. Apparently the three of you have collaborated in the past. It's a pleasure to meet you.

2. Singles, also often see a single 250k pot plus amp input (ie the same as 1), based on bridge positions on Strats, either classic wiring (no B tone), or modern Am Standard with a no-load tone pot.

That makes sense. I've always hated the sound of the bridge pickup on a Strat when used alone. It just sounds horribly brittle to my ears. A bit less so on one that has been modified so the middle pickup alone is the one without a tone control.

With many pickups, if you model them with 2x250k pots plus 1M = 111k, or thereabouts, the resonant peak is largely killed off, making the data much less useful.

Thanks for the explanation.

[reTrEaD]

It's kind of interesting when you consider that Strat pickups have such a high Q factor due to the utter lack of eddy current losses, and then guitarists use 250k pots to basically cause similar losses. It suggests that a high Q factor is not such a prized quality, and that guitarists are looking for a softer knee at the peak.

I would imagine in some cases it's a conscious choice after trial and error but in more cases it's because that's what Leo did so that must be what we should do.

All this technical stuff can be a bit daunting but I reckon as one gets more familiar with it, they can begin to understand how certain things factor into what appeals to their personal tastes.

I tend to gravitate toward "smooth" and prefer the sound of HBs with covers to those without. I would imagine that I'd prefer single-coil pickups with a peak that is at a higher frequency but has been tamed down in amplitude to a very modest level.

[antigua]

Sept 27, 2016 17:23:00 GMT -5 reTrEaD said:

It's kind of interesting when you consider that Strat pickups have such a high Q factor due to the utter lack of eddy current losses, and then guitarists use 250k pots to basically cause similar losses. It suggests that a high Q factor is not such a prized quality, and that guitarists are looking for a softer knee at the peak.

I would imagine in some cases it's a conscious choice after trial and error but in more cases it's because that's what Leo did so that must be what we should do.

All this technical stuff can be a bit daunting but I reckon as one gets more familiar with it, they can begin to understand how certain things factor into what appeals to their personal tastes.

I tend to gravitate toward "smooth" and prefer the sound of HBs with covers to those without. I would imagine that I'd prefer single-coil pickups with a peak that is at a higher frequency but has been tamed down in amplitude to a very modest level.

It sounds like you prefer a low Q factor. Something a lot of people don't realize is that you can also lower the Q factor just by rolling to tone knob back slightly, to 8 or 9, and then adjust the treble on your amp if there is too much loss of treble as a result.