In most cases, I buy pickups to study them a bit closer in this case I had some help because these pickups were on sale a few weeks back. The pickups I am talking about are the Golden Age series from StewMac, named the “Vintage Vibe”. Even though I hade some bad luck with one of their Gibson style pickups, the Parson Street ones, some time ago I went ahead and bought them. What happened to these Parson Street HBs was a result of poor construction that ended in them being unusable. The output lead was was soldered directly to the thin copper wire without the usual lead wires that are firmly attached with the tape wound around the coil. So these fancy pickups never got tested or ending up in a guitar. Anyway, I showed good faith by getting the Vintage Vibe and testing them. Usually, I take a pickup apart completely when I do this, but this time I do not want to do that because I will try them out in a guitar before I do that, if I do.
First thing I did was a parametric evaluation of the pickups, one was for the Bridge and the other for the Neck positions. I have described how I measure and calculate parameters elsewhere. In this and many other situations, I use my LCR meter to measure resistance and inductance, not the “fancy” way of determining inductance as described before. Same thing with resonance frequency and flux density, measured as already described. Capacitance was as always calculated using the method described.
I was intrigued about the “Vintage Vibe” description and wanted to see what that was about. The pickups are the slug/screw type which is not why I got them, since I do not really like the screws in a pickup, I prefer a slug/slug type or even better a rails PUs. I got the black/black version without the cover, I think I have some covers that could be used. The first thing to be examined is the construction. The pickup itself is pretty standard so the next step is the cable which is the wound foil with a drain wire type, not my favorite, but the type has proven to be sufficient for guitar PUs to provide shielding. Besides that, there are 4 wires connecting to the coils, green and red to the screw side and black and white to the slug side. The red and white come soldered together, they are the “finish” wires for the two coils, where green and black are the “start” wires. The two coils are wound the usual way opposite each other and with poles being of opposite “polarity” as a humbucker should be. If you have read the main page “Guitar Electronics”, you know that I dislike any other connection that the standard connection that would not necessitate the red and white wires to be brought out, but it comes in handy for measurement of the individual coils, so I might as well use that. A lot of different connections and combinations are shown in the instructions also different soldering methods which I do not recommend in case where you shield your guitar. As described elsewhere, you are well under way to shielding just with the cable provided with the PUs. As you may know, I also have series issues with the “hot” and especially with the “ground” designations, none which have any place when it comes to shielding, all that and much more under “Shielding Your Guitar”.
Static Measurements
Starting with the measurements of R, L and fo for the total HB and for the individual coils and calculate C. I also measure the flux density at the pole surfaces with a flux meter. The first set of results can be seen in Table 1.
| kOhm | Henry | kHz | pF | |||||||||
| Golden PU | Rgb | Rgrw | Rbrw | Lgb | Lgrw | Lbrw | fogb | fogrw | fobrw | Cgb | Cgrw | Cbrw |
| Bridge | 9.34 | 4.65 | 4.68 | 5.42 | 2.29 | 2.34 | 10.2 | 14 | 10.52 | 44.9 | 56.4 | 97.8 |
| Neck | 8.01 | 4.03 | 3.98 | 4.55 | 1.93 | 2.01 | 10.75 | 15.2 | 10.8 | 48.2 | 56.8 | 108.0 |
The only data that were indicated for the pickups from StewMac was the total coil resistance, in this case listed as Rgb, green to black with red and white soldered together. This value does not mean a whole lot other that it may give you an idea (in connection with L) how many turn on the coil, if you know the wire size used in winding the PU. So you only know one of three parameters necessary, as I said, not very useful. The inductance values are not unexpected for what it supposed to be a “vintage” pickup, in general lightly wound. The measured resonance frequency, fo, is a bit on the high side for an HB pickup, but since it is lightly wound, that would be expected. The higher fo for the green to red/white, is undoubtedly because that coil has the screws resulting in a much lower coil capacitance, see Cgrw compared to Cbrw. As the Table 1 shows, the three capacitances for each pickup are “in harmony”. That means, that Cgb is a series connection of the two individual coil capacitances. Same for the inductances, where the total inductance in roughly the sum of the two individual inductances. Why it is not exactly the sum of the two is explained under “Pickup Inductance”.
| Flux, Gauss | Slug | Screw | Sc slot |
| Bridge | 290 | 300 | 264 |
| Neck | 275 | 270 | N/M |
Table 2 shows the measured flux densities, Bo, at the top of the slugs and screws, the “Screw Slot” column is the density measured right over the slot in the screw, the probe used is so tiny that it can sense the difference between the solid part of the screw and the slot, it was only measured for the Bridge PU. The point is, will it affect the sound, a string can be tiny too.
Dynamic Tests
The following tests were performed using one of my PU Testers. These testers have been described elsewhere on this site, but simply put, the use a real guitar string that moves in a way that would produce a sinusoidal signal if the pickup was a linear device. Since a PU is not a linear device such a tester will bring out the harmonics produced by the pickup only, without influence from the string movement that is typical in a guitar. This means we are evaluating the pickup and only the pickup.
The interesting part here is to find out what makes this a pickup “vintage” and how does that distinguish it from other pickups. Fig 1 will show the signals from the two different PUs at the 3rd pole position and a string height of 5 mm.
Both pickup types are equipped with AlNiCo 5 magnets arranged as is typical for a humbucker. Looking at the static data above, the curves should not be very different and they are not. What makes this PU “vintage”, the shape of the curves are pretty standard (see other examples on this site), the signal output is one the low side of an HB pickup maybe that is the “vintage” part. Your guess is as good as mine.
Looking at individual coils
Now that we have the red and white wires brought out, as we used it in the static measurements we may have a look at what the individual signals look like, Fig 2.
Now they act as single coil pickups and as would be expected with a lot of noise. As can be seen in Fig 2, they are also out of phase. And just to confirm that we can recreate the real humbucker signal we “add” the two signals as it would happen in a HB.
Back to the noise free signal from a HB as we can see in Fig 3. I guess at some point I might do an “on paper” frequency analysis of the signal just to investigate the “vintage” thing a bit further. At some point, I will add a frequency analyzer measurement to it, after it has been mounted in a guitar, using my ProTools with Blue Cat plug-in.
Simulation Analysis
Now that we have the individual parameters measured and calculated, we might as well try to run some calculations in a circuit analysis program. Here it is done in three steps, with the PU alone, the basic spectrum analysis after that with a single resistor as a load and finally with a cable and amplifier attached by adding a 600pF capacitor (cable) and a 1M resistor representing the input impedance of an amp in a simplified version. The schematic for the total is showed in Fig 4.
As mentioned, except for the PU itself, the circuit is simplified which should suffice to indicate what happens to the PU signal. The expanded circuit schematic will not bring much in that respect, other than complicate the explanation of the issues. The frequency spectrum that is shown in Fig 5 shows all three situations on the same graph sheet to make it easier to compare.
The blue curve is for the complete circuit as shown in Fig 4, even though it is not mentioned, it amp input impedance is included as well. The red curve is for the PU alone without the external load (cable, resistor and amp). The “control” circuit has not been added here, it has been discussed elsewhere and as you probably know by now, I do not use traditional “control” circuitry in my guitars. The orange curve is the characteristic with the 320k resistor as the only load for the PU, this is my favorite and is also a representation of what you would get with an active PU, assuming that the active part is designed as indicated one the main ” Guitar Electronics” page.
Conclusion
All in all a pretty regular PU set. Again the vintage part is most likely the modest output from the PU since there is not anything else special about them. Bottom line a pretty good buy from my present stand point. This is a strict technical evaluation not a subjective test where someone plays. Finally, I have to repeat myself concerning the use of the word “ground”. I know it has been and still is used instead of what we electronics engineers call the part of the circuit: “Common”. In this case, I want to point your attention to the instructions that accompany the pickup. There is a page that is showing six different switch combinations and there is a symbol used for “ground” and it is not the symbol used in Fig 4 for “common”. The symbol used is specifically assigned to “Earth Ground” which is nowhere to be found in a guitar, for one thing and another thing is to use this symbol indicates that whatever is connected to it is connected to a copper pole rammed into the ground (earth ground). The symbol indicates that there is a safe connection to Earth Ground guaranteeing electric safety. I have in a long career in electrical engineering had to be very careful using that symbol because advertising Earth Ground where it does not exist (like inside your guitar) can get you sued! Another thing I am opposed to as you may know if you have read the rest of this website, soldering anything to the pots is really foolish, especially when the guitar is shielded and normally it will just enhance the noise. Pot cases and “ground” have nothing in common (no pun intended). The background for this has been explained on other pages on this website as mentioned. I think that is it for now.