Prof - at your instigation, I’ve spent a lot of time with the 02 during this past year. It is small, shipable, simple and inexpensive. It provides a good development platform and test bed for many ideas which can be inexpensively iterated multiple times. I presently have 6 units for comparison and beta use and would buy more if they came along.
I don’t yet have a way to measure impedance. The woofer is 6 ohms and the tweeter is 8. The Stereo Magazine review states the bass double peak at 18 and 17.5 ohms (quite mild) with the saddle at 5.4 ohms and absolute minimum of 4.75 ohms at 170 and 10kHz - averaging 6 ohms, which is what we called it. Those loads are mild and easy to drive compared with modern Thiels. Several of us here agree that a minimum of 4 ohms would make Thiel products so much friendlier to such a wider range of users.
That said, the 02 has no Zobel or other corrective networks, so it presents a less resistive load than modern Thiels. More reactivity is harder to drive. The crossover is a straight-forward second order x polarity correct design. So, the tweeter signal arrives before the woofer, but the soft diaphragms allow a sweet, seamless crosspoint transition. The Gefco woofer has a proprietary pulp cone which is quite exceptionally smooth over its entire range, gently rolling off up to fully 10kHz. The Peerless fabric dome (we called it silk, but I don’t know) was the darling of the day, used by Polk and nearly everyone else. Nice, smooth tweeter with no real misbehavior. All that said, the drivers use conventional motors, coils and materials, unlike later Thiels that reduced distortion by more than a factor of 10x. Similarly, the cabinet is unbraced albeit veneered both sides on industrial particleboard for greater stiffness than MDF. And the crossover components preceded audiophile components. We self-wound the unpotted coils from standard CDA110-ETP wire. Resistors and caps were "better" grade parts bin quality and hookup wire was standard, stranded in PVC or vinyl. In other words, nothing special except attention to simplicity and longevity.
My work this year would take an essay to summarize, but let’s say that every change I made created a clearer, tighter, more Thiel-like presentation. Potting the coils in varnish - then replacing with CDA101, solid CDA101 wire in teflon, etc. etc. etc. But nonetheless, the original stock speaker has an easy, friendly presentation, like coming home to love. I hear it, I get it and I even have developed some theories about whys and wherefores. One summary thought is that the stock 02 sounds like what we (especially from our long-ago youth) expect to hear. Audio neurology is very synthetic and wired to clues, cues and expectations far more than we generally realize.
As a reference, my lab mule has migrated from stock 02 to hot-rodded 02 with original drivers > time aligned at second order. (That is the SCS format.) Then I substituted CS.5 drivers which are stellar.The woofer is cellulose / wool pulp with all the Thiel motor juju. I compared first vs second order crossovers executed (eventually) with CS7 style components, and landed firmly on the first order x time-aligned configuration. The workhorse value of this hot-rodded version is far superior. It no longer has that ’old shoe’ familiarity that you appreciate, but it shines with joy. The present iteration has rounded (1.5" radius) grille edges, braced cabinet, and lots of new technologies. Since it's not coincident, its coherence varies with ear position. I made an easily adjustable stand for seated through standing tweeter height. And the fun never ends.
The form-factor is an original 02, the execution incorporates some beyond-Jim elements. But no coaxes or x.7 style drivers. Presently I'm looking for new lab space while liquidating my tonewood enterprise.
I don’t yet have a way to measure impedance. The woofer is 6 ohms and the tweeter is 8. The Stereo Magazine review states the bass double peak at 18 and 17.5 ohms (quite mild) with the saddle at 5.4 ohms and absolute minimum of 4.75 ohms at 170 and 10kHz - averaging 6 ohms, which is what we called it. Those loads are mild and easy to drive compared with modern Thiels. Several of us here agree that a minimum of 4 ohms would make Thiel products so much friendlier to such a wider range of users.
That said, the 02 has no Zobel or other corrective networks, so it presents a less resistive load than modern Thiels. More reactivity is harder to drive. The crossover is a straight-forward second order x polarity correct design. So, the tweeter signal arrives before the woofer, but the soft diaphragms allow a sweet, seamless crosspoint transition. The Gefco woofer has a proprietary pulp cone which is quite exceptionally smooth over its entire range, gently rolling off up to fully 10kHz. The Peerless fabric dome (we called it silk, but I don’t know) was the darling of the day, used by Polk and nearly everyone else. Nice, smooth tweeter with no real misbehavior. All that said, the drivers use conventional motors, coils and materials, unlike later Thiels that reduced distortion by more than a factor of 10x. Similarly, the cabinet is unbraced albeit veneered both sides on industrial particleboard for greater stiffness than MDF. And the crossover components preceded audiophile components. We self-wound the unpotted coils from standard CDA110-ETP wire. Resistors and caps were "better" grade parts bin quality and hookup wire was standard, stranded in PVC or vinyl. In other words, nothing special except attention to simplicity and longevity.
My work this year would take an essay to summarize, but let’s say that every change I made created a clearer, tighter, more Thiel-like presentation. Potting the coils in varnish - then replacing with CDA101, solid CDA101 wire in teflon, etc. etc. etc. But nonetheless, the original stock speaker has an easy, friendly presentation, like coming home to love. I hear it, I get it and I even have developed some theories about whys and wherefores. One summary thought is that the stock 02 sounds like what we (especially from our long-ago youth) expect to hear. Audio neurology is very synthetic and wired to clues, cues and expectations far more than we generally realize.
As a reference, my lab mule has migrated from stock 02 to hot-rodded 02 with original drivers > time aligned at second order. (That is the SCS format.) Then I substituted CS.5 drivers which are stellar.The woofer is cellulose / wool pulp with all the Thiel motor juju. I compared first vs second order crossovers executed (eventually) with CS7 style components, and landed firmly on the first order x time-aligned configuration. The workhorse value of this hot-rodded version is far superior. It no longer has that ’old shoe’ familiarity that you appreciate, but it shines with joy. The present iteration has rounded (1.5" radius) grille edges, braced cabinet, and lots of new technologies. Since it's not coincident, its coherence varies with ear position. I made an easily adjustable stand for seated through standing tweeter height. And the fun never ends.
The form-factor is an original 02, the execution incorporates some beyond-Jim elements. But no coaxes or x.7 style drivers. Presently I'm looking for new lab space while liquidating my tonewood enterprise.