Burns Tri-Sonic set for Strat, Analysis & Review Nov 20, 2018 0:53:16 GMT -5
Post by antigua on Nov 20, 2018 0:53:16 GMT -5
The Burns Tri-Sonics pickups are mostly associated with Brian May, who put a set of three of them in a guitar he put together called the "Red Special", but otherwise were found in Burns guitars.
These Stratocaster versions are smaller than the original, and appear to be constructed somewhat differently. I know that both designs feature ceramic magnets. They have a "BHK" sticker on the back , which is apparently the mark of a pickup manufacturer in Korea that has made pickups for various budget priced instruments, though most of the pickups I have seen from them are well made, especially the Fender Fideli'trons.
But since these are meant to be fitted into a Strat, the more important question is probably, how do they compare to AlNiCo Strat pickups? Similar to Strat pickups, they have a magnet in the coil, rather that below the coil, like a P-90 or a Filter'tron, but it's just one large, ceramic bar magnet. The ceramic magnet is non conductive and likely non permeable, unlike AlNiCo or steel, so the ceramic magnet core neither increase the inductance, not causes eddy currents, but nevertheless, there are a high degree of eddy current losses due to the metal cover and base plate, causing the Tri-Sonic to have virtually no resonant Q factor. Most all Fender single coils little or no extra metal parts involved, show very little eddy current losses, and have a high resonant Q, which is a feature of the "Fender sound". Otherwise you're left with a soft roll-off of the treble.
Looking at the top of the pickup, you see six holes and some textured black vinyl below. Under that layer is foil shielding that surrounds all of the coil except for the ends, and then under the foil is the large ceramic bar magnet core.
Speaking of the Fender Fideli'trons, the Tri-Sonic for Strats are comparable to Filter'trons in a few respects, despite the lack of screw pole pieces and an AlNiCo magnet. First, the large about of steel and conductive metal causes the Tri-Sonic for Strat to show a high degree of eddy current losses, very similar to a Filter'tron. Second, the shape of the base plate and the chrome cover somewhat resemble a Filter'tron. Third, both have unusually low inductance values for a hi-Z guitar pickup. Another pickup they're probably very similar to are Danelectro "lipstick tube" pickups, because though I have yet to test one, there are notable similarities in terms of the structure and the electrical values.
The very low Q factor makes for a somewhat flat treble, with a soft foll off, but that doesn't mean the pickup is necessarily dark, because it has a very high resonant peak due to the very low inductance. The loaded resonant peak of the Tri-Sonic for Strat is around 5kHz, which begins to approach the limit of what a guitar amp will even put out, meaning the LC resonance of the pickup attenuates almost nothing that is audible. Most Strat pickup have resonant peaks around 4kHz, and most PAF type pickups around 2.5kHz. I haven't put these in a guitar yet, but I expect they will be fairly bright and thin, but the big roll off causes by the eddy currents might counteract the brightness, so I'll have to try them out and report back.
The magnetic pull at the strings appears to be very high, since there is a large ceramic magnet directly below the black vinyl which you can see though the cover holes. The gauss measures 1250G, which is even stronger than AlNiCo 5 Strat pole pieces, which I usually measure at around 1050G. Most guitar pickups with screws or slugs don't get much past 400G. I'll have to see whether "wolf tones" are a problem with these pickups as they tend to be with a regular AlNiCo 5 Strat pickup. OTOH, I think there's probably less temptation to set these pickups close to the strings, since the magnet does not protrude out the top of the pickup.
The chassis has it's own green wire, so that you can wire the pickups in phase / out of phase, like the Brian May Red Special, without any trouble.
Another note, a stock Strat comes with 250k pots, but the intention of that is to roll off the high Q of an AlNiCo poled single coil pickup. Since the Tri-Sonics have almost no Q factor, you'd probably get better results with 500k or even 1 meg pots. I understand the Brian May Red Special might have used 300k linear pots, but you can always replicate the effects of a lower value pot with a higher value but by just turning it down slightly. The higher value pot just gives you more range.
Burns London Mini Tri-Sonic Bridge
- DC Resistance: 9.56K ohms
- Measured L: 0.93H
- Calculated C: 315pF (325 - 10)
- Gauss: 1250G
Burns London Mini Tri-Sonic Middle
- DC Resistance: 8.63K ohms
- Measured L: 0.74H
- Calculated C: 350pF (360 - 10)
- Gauss: 1250G
Burns London Mini Tri-Sonic Neck
- DC Resistance: 8.59K ohms
- Measured L: 0.73H
- Calculated C: 310pF (320 - 10)
- Gauss: 1250G
Bridge unloaded: dV: -2.9dB f: 9.16kHz (black)
Bridge loaded (200k & 470pF): dV: -1.7dB f: 4.95kHz (blue)
Middle unloaded: dV: -3.6dB f: 9.70kHz (red)
Middle loaded (200k & 470pF): dV: -2.1dB f: 5.48kHz (green)
Neck unloaded: dV: -2.0dB f: 10.4kHz (pink)
Neck loaded (200k & 470pF): dV: -1.3dB f: 5.61kHz (black)
Note the big roll off, caused by the excessive eddy currents, but notice also that the drop off is past 5kHz, which is well into the high treble frequencies.
The pickups are wax potted:
base plate removed: