JRDG Company Special – Model 925 and 825
Model 925
2011-2022 (was not available in the Netherlands until 2013)
Retail price in 2013 in the Netherlands 69.500 euro
Retail price in 2016 in the Netherlands 81.000 euro
For a while, the 925 was no longer available in the Netherlands. In the meantime the 725 got introduced. Was it to be the replacement for the big 925? Now we know it was not, but for a while it seemed that Rowland had phased out the 925, judging from its absence from the 2012 brochure. Not compliant with EU regulations perhaps? Who knows. Fact is that it became available again (I even heard a pair at a demo) in 2013. JRDG do not disclose the precise amplification method used but it seems that the 925 employs nCore modules, this in contrast to the Pascal modules used for all their other switching amps, although I am not sure about the 825.
Model 825
2013-2022
Retail price in 2013 in the Netherlands 38.500 euro
Retail price in 2016 in the Netherlands 42.000 euro
It’s not clear to me which amplification modules are used but it must be either nCore or Pascal.
Model 925 Pictures
Prototype with flat-sided (no air vents) power supply
Model 825 Pictures
Model 825 at an audio show in 2016 in Veldhoven, the Netherlands.
625/725 and 825/925 differences
The 725’s use ceramic boards and some other novel tricks, which are said to make them sound more nuanced and transparent than the 625. While the 625 and 725 on their basic levels share similar technology, both being “traditional” analog bipolar transistor types, the 925, and I assume also the 825 which looks like a spin-off from the 925, are actually switch mode amplifiers using Pascal modules at their core, augmented with a lot of extra power regulation.
Model 925 Features
MACHINED ALUMINUM CHASSIS
Quad chassis precision-machined from solid bar-stock T-6061 aircraft grade aluminum providing exceptional thermal heat transfer/dissipation, RFI/EMI shielding, and resonance control.
FUNCTIONAL ISOLATION
The amplifier and power supply of each channel are isolated from each other in separate chassis. High-current DC power and low-current control signals are transferred between the amplifier and power supply via custom made detachable cables.
ACTIVE POWER FACTOR CORRECTION
Active Power Factor Correction (PFC) in the power supply reduces AC line harmonic noise pollution and increases AC line power utilization to 93%. Voltage and current demands from the amplifier remain in phase with each other which eliminates the transient, out-of-phase, high current pulses common to the operation of all other non-PFC audio power amplifiers.
HIGH-EFFICIENCY SWITCH-MODE POWER SUPPLY
Powerful, efficient, 2500W switch-mode power supply provides optimum voltage regulation for all circuits and operating conditions, and allows for quiet operation over a wide range of AC mains power sources.
ZERO-CURRENT SWITCHING
The power supply is comprised of four DC to DC converters incorporating “zero-current-switching” technology for high-efficiency and greatly reduced levels of conducted and radiated noise.
4 POLE CAPACITORS
Custom-made 4-pole capacitors integrated within the power supply further reduce any remaining residual noise.
NOISE ISOLATION
An isolated, discrete component, shunt-regulated power supply, providing over 130 decibels of noise isolation, offers low broadband noise and output impedance. This supplies noise-free DC power to all low-level audio circuitry for battery-like performance.
SOLID-STATE RELAY
AC Mains power is switched via a solid-state relay. Switching occurs only during the AC mains zero voltage crossing period dramatically reducing in-rush current during turn-on surges and providing a lifetime of trouble-free switching.
CERAMIC CIRCUIT BOARDS
All input circuitry is implemented on mil-spec, multi-layer, low dielectric constant, Rogers™ ultra-rigid ceramic circuit board substrate for extremely low energy retention and absorption.
BALANCED TOPOLOGY
Inherent cancellation effects of balanced topology implemented throughout all power and input/output circuits ensures greatly reduced distortion and noise under dynamic signal conditions.
HIGH-PRECISION SURFACE MOUNT COMPONENTS
Extensive use of Lead (Pb)-free, low temperature coefficient, active and passive surface-mount components results in significantly smaller loop areas, reduced circuit capacitance and inductance, and introduces less noise than conventional leaded components.
THIN FILM RESISTORS
All resistors are low-noise, 0.1% thin film Surface Mount Devices (SMD) type for extremely low thermal noise which complements the low-noise characteristics of the active circuitry.
TRANSFORMER-COUPLING AND ISOLATION
Transformer coupled input circuitry provides universal component compatibility, excellent common-mode noise rejection (CMRR) from the input source, and virtually eliminates ground loop noise and RFI/EMI. Transformer coupling ensures identical amplifier overall gain when using unbalanced inputs.
REAR PANEL CONTROLS
Rear panel switching of input phase, overall gain, and input selection (XLR/RCA).
CUSTOM INPUT JACKS
Both XLR and RCA input jacks are custom-made Cardas connectors constructed of copper, rhodium, gold, and Teflon materials for minimal signal loss and excellent corrosion resistance.
CUTTING-EDGE OUTPUT CIRCUITRY
Innovative class-D audio power technology is based upon a non-hysteresis 5th order self-oscillating control loop taking feedback only at the speaker output.
EXTREMELY LOW DISTORTION
Unique output circuitry ensures an extremely low distortion level of less than 0.004% THD + Noise over the entire audio spectrum of 20 Hz to 20 kHz powering any load ranging from 2 to 8 Ohms.
STABILITY AND FLEXIBILITY
An output impedance of less than 0.003 Ohms (3 milliohms) over the entire frequency range of 20 Hz to 20 kHz ensures that all loudspeaker types can be driven with impunity. Stability of the amplifier is guaranteed under all conditions when driving any loudspeaker or loudspeaker cable type.
ERROR DETECTION
Extensive microprocessor controlled error detection circuitry ensures protection of associated loudspeaker components under many extreme operating conditions.
HIGH-EFFICIENCY
A power efficiency of 93% at full power output afforded by this technology ensures low energy consumption, low operating temperature, and an extended service life of all components within the amplifier.
PARALLEL BINDING POSTS
Dual CE approved speaker output terminals require no tools for secure, low resistance connections, and allow for easy bi-wiring applications.
FLEXIBLE 20 AMP AC POWER
20 amp AC power inlet accepts a wide variety of after-market high-performance power cables.
FRONT PANEL STANDBY BUTTON
Illuminated front panel push-button switches the amplifier into standby mode. Separate stand-by circuitry reduces AC mains power to less than 1 watt during stand-by, ensuring international regulatory compliance.
REMOTE ON/OFF
A 1/8” (3.5mm) mini plug connector on rear panel permits amplifier power on/standby switching in remote and home theater applications.
SELF-LEVELING SUPPORTS
Removable 3-point self-leveling Delron chassis supports provide high frequency mechanical noise isolation.
Model 925 Technical Specifications
4-chassis mono power amp
Balanced design
Class A/B
OUTPUT POWER
430 watts @ 8 ohms/850 watts @ 4 ohms
POWER SUPPLY
2400 W regulated DC SMPS per channel, with Active Power Factor Correction (PFC).
FREQUENCY RESPONSE
5 Hz – 50 kHz
INPUT IMPEDANCE
40k ohms
THD + NOISE
0.004%, 20 Hz- 20 kHz
DAMPING FACTOR
> 1000, 20 Hz – 20 kHz
OVERALL GAIN
Switchable 26/32 dB
Combined AMPLIFIER chassis & POWER SUPPLY chassis WEIGHT
160.4 lb / 73 kg (per channel)
TOTAL DIMENSIONS (H/W/D)
16.5″ x 15.5″ x 16.25″ (per channel) 419mm x 394mm x 413mm
Model 825 Features
MACHINED ALUMINUM CHASSIS
Dual chassis precision-machined from solid bar-stock T-6061 aircraft grade aluminum providing exceptional thermal heat transfer/dissipation, RFI/EMI shielding, and resonance control.
FUNCTIONAL ISOLATION
The amplifier and power supply are isolated from each other in separate chassis. High-current DC power and low-current control signals are transferred between the amplifier and power supply via custom made detachable cables.
ACTIVE POWER FACTOR CORRECTION
Active Power Factor Correction (PFC) in the power supply reduces AC line harmonic noise pollution and increases AC line power utilization to 93%. Voltage and current demands from the amplifier remain in phase with each other which eliminates the transient, out-of-phase, high current pulses common to the operation of all other non-PFC audio power amplifiers.
HIGH-EFFICIENCY SWITCH-MODE POWER SUPPLY
Powerful, efficient, 2500W switch-mode power supply provides optimum voltage regulation for all circuits and operating conditions, and allows for quiet operation over a wide range of AC mains power sources.
ZERO-CURRENT SWITCHING
The power supply is comprised of four DC to DC converters incorporating “zero-current-switching” technology for high-efficiency and greatly reduced levels of conducted and radiated noise.
4 POLE CAPACITORS
Custom-made 4-pole capacitors integrated within the power supply further reduce any remaining residual noise.
NOISE ISOLATION
An isolated, discrete component, shunt-regulated power supply, providing over 130 decibels of noise isolation, offers low broadband noise and output impedance. This supplies noise-free DC power to all low-level audio circuitry for battery-like performance.
SOLID-STATE RELAY
AC Mains power is switched via a solid-state relay. Switching occurs only during the AC mains zero voltage crossing period dramatically reducing in-rush current during turn-on surges and providing a lifetime of trouble-free switching.
CERAMIC CIRCUIT BOARDS
All input circuitry is implemented on mil-spec, multi-layer, low dielectric constant, Rogers™ ultra-rigid ceramic circuit board substrate for extremely low energy retention and absorption.
BALANCED TOPOLOGY
Inherent cancellation effects of balanced topology implemented throughout all power and input/output circuits ensures greatly reduced distortion and noise under dynamic signal conditions.
HIGH-PRECISION SURFACE MOUNT COMPONENTS
Extensive use of Lead (Pb)-free, low temperature coefficient, active and passive surface-mount components results in significantly smaller loop areas, reduced circuit capacitance and inductance, and introduces less noise than conventional leaded components.
THIN FILM RESISTORS
All resistors are low-noise, 0.1% thin film Surface Mount Devices (SMD) type for extremely low thermal noise which complements the low-noise characteristics of the active circuitry.
TRANSFORMER-COUPLING AND ISOLATION
Transformer coupled input circuitry provides universal component compatibility, excellent common-mode noise rejection (CMRR) from the input source, and virtually eliminates ground loop noise and RFI/EMI. Transformer coupling ensures identical amplifier overall gain when using unbalanced inputs.
REAR PANEL CONTROLS
Rear panel switching of input phase, overall gain, and input selection (XLR/RCA). A “link switch” permits electrical linking of both right and left channels for bi-wiring applications.
CUSTOM INPUT JACKS
Both XLR and RCA input jacks are custom-made Cardas connectors constructed of copper, rhodium, gold, and Teflon materials for minimal signal loss and excellent corrosion resistance.
CUTTING-EDGE OUTPUT CIRCUITRY
Innovative class-D audio power technology is based upon a non-hysteresis 5th order self-oscillating control loop taking feedback only at the speaker output.
EXTREMELY LOW DISTORTION
Unique output circuitry ensures an extremely low distortion level of less than 0.004% THD + Noise over the entire audio spectrum of 20 Hz to 20 kHz powering any load ranging from 2 to 8 Ohms.
STABILITY AND FLEXIBILITY
An output impedance of less than 0.003 Ohms (3 milliohms) over the entire frequency range of 20 Hz to 20 kHz ensures that all loudspeaker types can be driven with impunity. Stability of the amplifier is guaranteed under all conditions when driving any loudspeaker or loudspeaker cable type.
ERROR DETECTION
Extensive microprocessor controlled error detection circuitry ensures protection of associated loudspeaker components under many extreme operating conditions.
HIGH-EFFICIENCY
A power efficiency of 93% at full power output afforded by this technology ensures low energy consumption, low operating temperature, and an extended service life of all components within the amplifier.
PARALLEL BINDING POSTS
Dual CE approved speaker output terminals require no tools for secure, low resistance connections, and allow for easy bi-wiring applications.
FLEXIBLE 20 AMP AC POWER
20 amp AC power inlet accepts a wide variety of after-market high-performance power cables.
FRONT PANEL STANDBY BUTTON
Illuminated front panel push-button switches the amplifier into standby mode. Separate stand-by circuitry reduces AC mains power to less than 1 watt during stand-by, ensuring international regulatory compliance.
REMOTE ON/OFF
A 1/8” (3.5mm) mini plug connector on rear panel permits amplifier power on/standby switching in remote and home theater applications.
SELF-LEVELING SUPPORTS
Removable 3-point self-leveling Delron chassis supports provide high frequency mechanical noise isolation.
Model 825 Technical Specifications
2-chassis stereo power amp: 1 audio chassis and 1 power supply chassis
OUTPUT POWER
400W @ 8 ohms/750W @ 4 ohms
FREQUENCY RESPONSE
5 Hz – 50 kHz
INPUT IMPEDANCE
40k ohms
THD + NOISE
0.004%, 20 Hz- 20 kHz
DAMPING FACTOR
> 1000, 20 Hz – 20 kHz
OVERALL GAIN
Switchable 26/32 dB
Combined AMPLIFIER chassis & POWER SUPPLY chassis WEIGHT
160.4 lb / 73 kg
TOTAL DIMENSIONS (H/W/D)
16.5″ x 15.5″ x 16.25″ — 419mm x 394mm x 413mm
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Hi Christiaan,
Would you happen to know what does the Aux power input/output do on top of the DC power input/output of the JR 825/925?
Thanks and regards,
Joey
Hi Joey, Not having used these amps I’m not entirely sure but from the info available to me it looks like the 825 uses two independent DC cables with different connectors between power supply and amplifier: DC as well as AUX.
Christiaan, had you got a chance to listen to the 925 monos in comparison to the later, more evolved, but in the hierarchy lesser 735 or even brand new 555 amps? Or do you have any second hand informations about sonic differences?
I never heard the 925, or the new 735, or 555. All I can say is that the 735 is a descendant of the 725 that I did hear, and which still sound similar to the “classic” linear JRDG amplifiers like the model 6. The 925, however, is a switching design (nCore or Pascal). Knowing how much the other Rowland Pascal designs deviated from the classic sound, I would expect the 925 also to sound different. But that is nothing more than a guesstimation. The 555 is a new design of which very little info is made public just yet. I do not know if it is a linear or switched design.
and as such, knowing how much
, so alas, I cannot comment.
Thank you for any information that you can deliver.
I for myself have the Pascal powered JR Daemon for 3 years now and like it a lot, a fantastic unit. And I have different other “nice” sounding tubes like Zanden and Kondo, so I know the really organic tube sound, too.