JRDG Company Special – Model 735
Model 735 (mono)
2020-2022
Retail price 49.900 euros per pair in the NL (incl. 21% BTW)
Externally very similar to the 725 but with a silver top-plate
Ah, yes, that’s what a JRDG-button should look like! Thumbs up!
Official Announcement April 29, 2020
Since the ending of production of the popular Model 725 Mono Amplifier in 2018, there has been an increasing demand for a replacement of this fine amplifier for use by discriminating music lovers and audiophiles worldwide.
By using the Model 725 as an acclaimed platform for ongoing research and development, a number of changes have been incorporated into the design of the new Model 735, which are discussed below.
After many hours of critical listening tests done on several input transformer types, and consultation with Per Lundahl of Lundahl Transformers AB in Sweden, it was decided to incorporate a custom designed cobalt-based amorphous core input transformer instead of the standard high permeability, mu metal lamination core type previously used in the 725. Despite a slight increase in measured low order harmonic distortion in the
low frequencies due to the amorphous construction, the increase in overall musical resolution, richness and expression throughout the overall frequency range due to the inclusion of this particular transformer became immediately apparent during listening tests.
Due to the continuing increase of electromagnetic and radio frequency interference and pollution throughout the world, an improved input filter
characteristic was incorporated in the input stage of the Model 735 to address this issue. Very small amounts of EMF interference from any source can have deleterious effects on sensitive input stages of all solid state circuitry, therefore these measures taken in the Model 735 yielded enhanced musical reproduction and background silence. A reduction of amplifier bandwidth to approximately 90 kHz was chosen and careful filter alignment achieved a very minimal group phase deviation, which guarantees signal fidelity.
Additional refinement of the error correction circuitry lowered the distortion well above 30 kHz to levels difficult to measure with modern test equipment. Although it may be difficult to determine if these measures yield substantial sonic benefit at this time, I feel it is still an exercise worthy of effort towards the advance of knowledge and understanding of amplifier circuit operation.
The ceramic substrate circuit board material is carried over from previous models and has been redesigned in some areas to accommodate some minor circuit improvements and additions. A new color has been chosen for a unique visual identifier.
A new muting circuit has been incorporated in the output circuitry to reduce noise during turn-on and turn-off transitions.
A new amplifier bottom cover has been designed with machined cavities to accept a proprietary damping material, secured in place with machined covers, which act as supporting feet for the amplifier. During the testing and evaluation of various damping materials and supporting elements, a material and configuration was found that completely isolates the amplifier chassis from its supporting structure, allowing the amplifier to express its full potential.
A new faceplate power standby button, similar to those used on other products in our line, augments aesthetic compatibility with other JRDG products. Operational status is now indicated with a subtle, white pin-point LED, reducing distraction in darkly lit listening rooms.
A new non-anodized machined top cover extends the clear faceplate elegance towards the rear of the unit, enhancing contrasting elements of the entire “machined from a solid block” chassis.
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