Skip Navigation Website Accessibility
216.291.7172 |


ThroBak KOSS-301 MXV set Shiny Nickel

Koss-301 MXV P.A.F. Pickup Repros - Made in USA
Neck 8.6k , Bridge 7.6k (Sam Li repair spec.), 7.7k bridge (Pre Repair Spec.)

Koss-301 MXV Specs.:
• Unequaled accuracy, copied from Koss Burst under supervision of current owner Kris Blakely.
• Available as a "Sam Li Style" Post-Repair Set or Pre-Repair Factory Spec. set.
• Neck pickup coils and bridge slug coil wound with vintage, Kalamazoo-era, Meteor ME-301 winder. 
• Bridge screw coil reverse hand wound "Sam Li Style" for Post Repair set.
• ThroBak Custom Vintage formulation long Alnico 2 magnets custom Made in USA.
• 1010 Steel Bobbin Mounting Screws.
• 42 AWG Plain Enamel Magnet wire and 42 AWG Heavy Formvar wire on bridge screw coil (Post-Repair Set).
• ThroBak Maximum Vintage™ PAF clone Butyrate bobbins, Made in USA.
• ThroBak Maximum Vintage™ PAF style baseplates, Made in USA.
• ThroBak Maximum Vintage™ PAF style covers, Made in USA.
• ThroBak Maximum Vintage™ PAF style vintage alloy pole screws and slugs, Made in USA.
• Vintage correct braided wire, Made in USA.

Koss-301 MXV Details

Paul Kossoff with uncovered PAF pickups photo.Paul Kossoff with Koss Burst.
How do you capture classic Paul Kossoff tone in a P.A.F. replica? Well the dream case scenario would be access to the very guitar once owned by Koss. When Kris Blakely, current owner of the Kossoff Burst, contacted ThroBak to make a set of Kossoff repro pickups, that dream became a reality. Under the supervision of Kris Blakely we were able to take careful gauss and resistance measurements and closely inspect the uncovered vintage PAF pickups in the Kossoff Burst. By applying this information to the prototype pickups and comparing them both in real time and in recorded tests against the Kossoff Burst, we feel we have nailed the P.A.F. tone of the pickups in the Kossoff Burst and made a set worthy of the guitar's legacy. The ThroBak Koss-301 MXV. A set with bridge pickup tones that are surprisingly hot and searing given the low resistance and a neck pickup tone that is rich and full.

As part of the research required to do a repro correctly we discovered some amazing details about the Kossoff PAF's that explain their distinctive tone. These details also led us to some interesting connections and mysteries that are shared with another legendary guitar, the Peter Green Burst, "Greeny".

The Unique Koss Wind

Paul Kossoff bridge PAF pickup photo.

Koss Burst bridge pickup.
Two important details of the PAF pickups in the Koss Burst informed how ThroBak chose to wind the reproduction pickups. The first of these details is the use of Steel bobbin mounting screws in the Koss PAF's. Based upon over a decade as the go to shop for vintage accurate PAF repairs, we recognized that PAF's with Steel Bobbin mounting screws from the late '58 to '59 era usually show the signature winding pattern of the Meteor-301 pickup winder. One of 4 four known pickup winding machines used by Gibson in the 1950's. With this knowledge we used ThroBak's vintage Meteor ME-301 for the machine wound coils of the ThroBak Koss-301 MXV P.A.F. pickup repros.

The second compelling detail is the fact that the bridge pickup screw coil of the Koss Burst bridge PAF has a very old rewind repair. The screw bobbin is physically mounted backwards on the baseplate and reverse wound with Formvar magnet wire! The age of the tape, repair history of the guitar and manner of the repair strongly point to an old hand guided rewind done by the legendary Sam Li, a U.K. luthier known for his finishing and wood working skills but also known for his "unconventional" pickup repairs.

The Koss Alnico Magnets

?Close inspection of the original uncovered Koss Burst pickups revealed long Alnico magnets with gauss readings at the poles that are perfect match for block charged A2 or A4 Alnico magnets. After A/B comparisons in the prototype pickups, it became clear that our ThroBak long A2, USA Made, repro magnets were a perfect match. Interestingly, previous efforts by Gibson to clone these pickups have used long A3 magnets which are not capable of the gauss levels of the original Koss PAF magnets. So the magnets in the vintage pickups cannot possibly be A3.

The Kossoff Burst - Peter Green Burst - Connection

Steel bobbin mounting screw PAF Pickup photo.Steel bobbin mounting screws on Koss PAF.
Both the Kossoff Burst and the Peter Green Burst are legends in their own right, but are there details common to both that contribute to the legendary voices of these guitars? When it comes to the PAF pickups, both guitars have PAF's with Steel bobbin mountings screws. Although a small detail, the Steel screws impact the tone and output of the pickup by adding an extra measure of aggressive bite when compared to Brass bobbin mounting screws. Less frequently used than Brass bobbin mounting screws, it is notable that fate would put Steel bobbin mounting screws in the PAF pickups of both guitars.

The Sam Li repair connection. Both the Greeny Burst and the Kossoff Burst have previously known repairs by U.K. luthier Sam Li. The Greeny Burst has a known pickup repair done by Sam Li and the Koss Burst has a neck repair done by Sam Li. But when it comes to the Kossoff Burst, we now know it has a bridge pickup that also shows the hallmark quirks of a Sam Li PAF pickup rewind repair.

Peter Green Pickup Repair Points
Perhaps the most legendary and mysterious guitar story, when it come to vintage PAF pickups, is how did Peter Green's Burst get the middle position out of phase tone and why does it have such a distinctive neck pickup tone. We will not know for certain what is going in with the Peter Green neck pickup until the covers comes off again one day, but as a pickup maker, the most plausible explanation of the Peter Green PAF repair came to me through Bharat Khandekar, a well know luthier and friend of Sam Li's. As a PAF pickup expert in his own right, Bharat was kind enough to share his knowledge with ThroBak when we were planning ThroBak Maximum Vintage parts more than a decade ago. In my conversations with Bharat the Peter Green Burst tone and pickup repair question came up. Below is a point by point outline of my reconstruction of the Peter Green neck pickup repair as I believe it to be when taking into account the information provided by Bharat.

• While playing with John Mayall, Peter Green brought his guitar to Sam Li for a neck pickup repair.
• Sam Li determines that one neck pickup coil needs a rewind.
• Sam Li rewinds the coil with Heavy Formvar wire on hand from a previous Fender pickup repair.
• Inexperienced with pickup repairs, Sam Li rewinds the failed PAF coil in the reverse direction using a record turn table.
• Because of the reverse wound coil, the assembled pickup is out of phase with itself and Peter Green returns the pickup saying it does not sound right.
• In his quest to fix the problem, Sam Li reverses the start/finish wiring of the repaired coil which fixes the internal pickup phase issue but accidentally flips the magnet in the process, causing the neck and bridge pickups to be out of phase in the middle position.
• Not fully understanding the phase relationship, Sam Li also mounts the neck pickup backwards into the guitar as a possible remedy.
• Peter Green picks up the guitar, with Sam Li recounting the episode to Baharat that, "Since the guitar did not come back, it must be fixed".

For me as a pickup maker, the most interesting tonal details of this story are the reverse wound Formvar wire rewind, changing the signal direction of the rewound coil and the magnet flip. All of these impact the tone of the pickup. Since Sam Li was not well experienced in the phase relationship of wind direction, signal direction and magnet polarity his approach to the repair makes sense given the early days of electric guitar repair and the limited need for rewind repairs.

Paul Kossoff PAF Pickup Detail PhotoKoss Burst bridge pickup.
The Koss Burst "Sam Li Style" Pickup Repair
Lets look at what we know about the Koss Burst bridge pickup repair. We already know Sam Li repaired the neck of the Koss Burst but are there common details with the Peter Green pickup repair that might also point to Sam Li as the repair person of the Koss Burst pickup? The first common detail is a screw pickup coil reverse wound with Formvar on the Koss Burst pickup. The Second detail common to both is a reversing of the start finish relationship of the rewound coil. The third detail is a neck magnet flip, yes that's right, the Koss Burst has a neck pickup magnet flip also. However the Koss middle position is in phase because the bridge pickup also has been accidentally rewired to reverse the electronic phase of the pickup. If we were looking at just one guitar, with one pickup repaired, these repair errors seem random. But to see these same errors repeated in two famous guitars, that both were serviced by Sam Li, strongly points to Sam Li as the PAF repair person for both the Peter Green Burst and the Koss Burst.

So the question then remains, if Sam Li did repair the pickup in the Kossoff Burst, when was it done? Well we know that Sam Li repaired the neck of the guitar after the last Free show. Was it done then? The covers came off the pickups after this repair and stayed off through Paul Kossoff's Backstreet Crawler days. Perhaps this is an important clue. We do know the repair is very old, looks like a Sam Li job and the repair resulted in a pickup that sounds fantastic! However, to cover the full range of historical possibilities, we are offering both a Post-Repair, "Sam Li Style" set and a Pre-Repair, Factory Spec. set. We will leave it up to as to which set to buy, but I for one am going to have to have both!

Meteor ME-301 Wound

Vintage Metero pickup winder.
Sparing no expense in the quest for absolute accuracy, ThroBak located a vintage Meteor ME-301 winder and restored the machine's wire guides, tensioning and traverse to the configuration of the original Kalamazoo era Meteor ME-301 winders. We contacted former Kalamazoo plant employees, scoured historical records to gather detailed vintage photos in order to pull off the daunting, but crucial task of recreating the vintage ME-301 winder as they where in the old Kalamazoo plant. Changes made to the traverse and fixtures following the Kalamazoo move meant that crucial lost vintage details to wire guides and tension had to be accurately reproduced to meet the ThroBak Maximum Vintage standard. But we are proud to say we did it! Accuracy in these details combined with the unique winding pattern that is the signature of the ME-301 mean we can turn back the clock and offer unsurpassed vintage accuracy for the Koss-301 MXV set.