{"id":9544,"date":"2010-04-26T21:03:18","date_gmt":"2010-04-26T19:03:18","guid":{"rendered":"http:\/\/www.hifi-advice.com\/blog\/?page_id=9544"},"modified":"2018-02-03T13:46:03","modified_gmt":"2018-02-03T11:46:03","slug":"jrdg-company-special-model-302-301-312-304","status":"publish","type":"page","link":"https:\/\/www.hifi-advice.com\/blog\/jeff-rowland-power-amplifiers\/jrdg-company-special-model-302-301-312-304\/","title":{"rendered":"JRDG Company Special – Model 302, 301, 312, 304"},"content":{"rendered":"

<\/b>Model 302<\/strong><\/h2>\n

2002-2009<\/strong>
\nRetail prices in 2007 in Germany:
\nModel 302 2 x 300 W – ICE-Pack-Amp \u00a017.398,00
\nModel 302-handles 2 x 300 W – as above, with handles\u00a0 17.998,00
\nModel 302\/4 – 2 x 300 W – 4-Module-Amp for\u00a0Bi-amping. \u00a018.698,00
\nModel 302\/4-handles – 2 x 300 W – as above, with handles 19.398,00<\/p>\n

\"rowland-model-300-front_550pix\"<\/p>\n

Rowland’s 302 was the first high end approach to using ICE-power. Inside is a huge power transformer but it isn’t used in the regular way, instead it is used for filtering. After that follows the power factor correction, followed by a switched power supply. This amp can be fitted with one, two or four ICE-power channels according to taste. With 2 channels installed, 300 watts are available, dropping to 250 watts when 4 channels are installed. This is because the modules are fed from the same 1200 watt power supply.<\/p>\n

\n

Model 301, 312, 304<\/h2>\n

Approx 2009-2012
\n<\/strong>Retail prices\u00a0unknown<\/p>\n

\"rowland-312-front_550pix\"<\/p>\n

Housed in the same chassis, but following up on the model 302 this is the next high end approach to using ICE-power. As far as I can find out these models use the same electronics as thhe previous 302. Perhaps it was only a nomenclature change. Inside is a huge power transformer but it isn’t used in the regular way, instead it is used for filtering. After that follows the power factor correction, followed by a switched power supply. This amp can be fitted with one, two or four ICE-power channels according to taste. With 2 channels installed, 300 watts are available, dropping to 250 watts when 4 channels are installed. This is because the modules are fed from the same 1200 watt power supply. The 301 is mono, 312 is stereo and 304 is 4-channel.<\/p>\n

Two generations of 301<\/strong><\/p>\n

There were two generations of 301, the second gen starts with serial number 72. The most obvious difference is in the ICE power module used but there’s more. See below for a complete overview.<\/p>\n

Serial numbers and production years:<\/strong><\/p>\n

    \n
  • Original version units of the Model 301 have serial numbers ranging from MA0002 through MA0071. These units were manufactured from March 2003 through October 2005<\/li>\n
  • New version units of the Model 301 have serial numbers starting from MA0072 and higher. These units were manufactured from November 2005 to the present.<\/li>\n<\/ul>\n

    Different front end power supplies for the second generation:<\/p>\n

      \n
    • Original version utilizes a isolation power transformer followed by two 700W power factor correction (PFC) modules, followed by two 600W<\/li>\n
    • Vicor DC-DC converters.<\/li>\n
    • New versions eliminates the transformer and utilizes a single universal AC input 1200W active PFC\/SMPS module.<\/li>\n
    • Both utilize the same low voltage power supply.<\/li>\n<\/ul>\n

      ICEpower modules:<\/p>\n

        \n
      • Old – ICEpower500A MK2 modules<\/li>\n
      • New – ICEpower1000ASP modules<\/li>\n<\/ul>\n

        Output power rating differences:<\/p>\n

          \n
        • Old, parallel: 400W @8 ohms, 650W @4 ohms<\/li>\n
        • New, parallel: 600W @8 ohms, 1200W @4 ohms<\/li>\n<\/ul>\n
          \n

          Model 301 Pictures<\/h2>\n

          \"rowland-model-301_new-500pix\"<\/p>\n

          \"rowland-301-back-mooi_550pix\"<\/p>\n

          \"rowland-model-301_new-rear_467pix\"<\/p>\n

          \"rowland-model-301_new-inside_311pix\"<\/p>\n

          Above you can see the bottom section of the 301’s insides. The metal plate divides the unit in two sections and the ICE power units are in the top section.<\/p>\n

          \n

          Model 302 Pictures<\/h2>\n

          \"rowland-model-302-rear-500pix\"<\/p>\n

          \"rowland-model-302-in-stereo-500pix\"<\/p>\n

          Switching powersupply on the left, bottom circuitboard and Power Factor Correctors on the right<\/p>\n

          \"rowland-model-302-inside-stereo-500pix\"<\/p>\n

          Above: 2 channel version of the model 302. The big transformer isn’t used in the normal fashion but as an extra filterstage before the swithcing power supply.<\/p>\n

          \"rowland-model-302-inside_516pix\"<\/p>\n

          Above: 4 channel version of the model 302<\/p>\n

          \"OLYMPUS<\/p>\n

          Above: input board<\/p>\n

          \n

          Model 312 Pictures<\/h2>\n

          \"rowland-312-rear_550pix\"<\/p>\n

          Model 312 rear is almost identical to the 302 rear panel<\/p>\n

          \"rowland-model-312-1_550pix\"<\/p>\n

          Model 312 utilises more modern ICE power modules.<\/p>\n

          \"rowland-model-312-2_550pix\"<\/p>\n

          \n

          Model 301 Versions<\/h2>\n

          There were two generations of 301, the second gen starts with serial number 72. The most obvious difference is in the ICE power module used but there’s more. See below for a complete overview.<\/p>\n

          Serial numbers and production years:<\/strong><\/p>\n

            \n
          • Original version units of the Model 301 have serial numbers ranging from MA0002 through MA0071. These units were manufactured from March 2003 through October 2005<\/li>\n
          • New version units of the Model 301 have serial numbers starting from MA0072 and higher. These units were manufactured from November 2005 to the present.<\/li>\n<\/ul>\n

            Different front end power supplies for the second generation:<\/p>\n

              \n
            • Original version utilizes a isolation power transformer followed by two 700W power factor correction (PFC) modules, followed by two 600W<\/li>\n
            • Vicor DC-DC converters.<\/li>\n
            • New versions eliminates the transformer and utilizes a single universal AC input 1200W active PFC\/SMPS module.<\/li>\n
            • Both utilize the same low voltage power supply.<\/li>\n<\/ul>\n

              ICEpower modules:<\/p>\n

                \n
              • Old – ICEpower500A MK2 modules<\/li>\n
              • New – ICEpower1000ASP modules<\/li>\n<\/ul>\n

                Output power rating differences:<\/p>\n

                  \n
                • Old, parallel: 400W @8 ohms, 650W @4 ohms<\/li>\n
                • New, parallel: 600W @8 ohms, 1200W @4 ohms<\/li>\n<\/ul>\n

                  Model 301 Technical Specifications<\/h2>\n

                  (second generation)<\/p>\n

                  Output Power @ 8 ohms
                  \nContinuous RMS 1800\/600 watts (ser\/par)<\/p>\n

                  Output Power @ 4 ohms
                  \nContinuous RMS NA\/1200 watts (ser\/par)<\/p>\n

                  Frequency Response
                  \n10 Hz – 60 kHz, 3dB<\/p>\n

                  Peak Output Current
                  \n> 90 amps<\/p>\n

                  Dynamic Range
                  \n120 dba<\/p>\n

                  THD + Noise
                  \n0.1W-500W\/4 ohm
                  \ntyp. .006% @ 1kHz<\/p>\n

                  CCIF Intermod. Dist.
                  \n19\/20kHz < .002%<\/p>\n

                  Damping Factor
                  \n60<\/p>\n

                  Common Mode Rejection Ratio
                  \n>90dB, 20 Hz 20 kHz<\/p>\n

                  Amplifier Weight
                  \n80 lbs each<\/p>\n

                  Amplifier Dimensions
                  \n10.6″ x 15.5″ x 18.3″<\/p>\n

                  \n

                  Model 302 Features<\/h2>\n

                  XLR input connectors for balanced system configuration.<\/p>\n

                  RCA input connectors for unbalanced system configurations.<\/p>\n

                  Dual Speaker Output Terminals on each channel for bi-wiring applications.<\/p>\n

                  User selectable switching between balanced and unbalanced connections.<\/p>\n

                  Transformer coupled inputs provide universal compatibility with other components and eliminate
                  \nground loop noise and EMI.<\/p>\n

                  Ultra-high efficiency output section generates high power output with very little heat.<\/p>\n

                  Fully-balanced circuit topology implemented from input to output.<\/p>\n

                  Power Factor correction in power supply reduces AC line harmonic noise pollution and increases
                  \nAC line power utilization to 99%.<\/p>\n

                  Proprietary switch-mode power supply technology ensures consistent performance under all
                  \noperating conditions.<\/p>\n

                  12V remote ON\/OFF remote power switching via 1\/8\u201d jack on rear panel.<\/p>\n

                  CE approved speaker output terminals require no tools for secure, low resistance connections.<\/p>\n

                  Standby power mode reduces warm-up time.<\/p>\n

                  Fail-safe operation provided by user-resetable thermal circuit breaker located on rear panel.<\/p>\n

                  Quiet, transient-free operation during power ON\/OFF and input configuration switching.<\/p>\n

                  Selectable overall gain of 26 or 32 dB.<\/p>\n

                  Ultra-low resonance, structurally rigid chassis constructed of precision-machined aircraft grade
                  \n6061-T6 aluminum.<\/p>\n

                  3-point self-leveling chassis support.<\/p>\n

                  Model 302\u00a0Technical Specifications<\/h2>\n

                  Output Power: Continuous RMS watts, both channels driven<\/strong>
                  \n@ 8 ohms 300 watts
                  \n@ 4 ohms 500 watts<\/p>\n

                  Power Bandwidth:<\/strong>
                  \n5 Hz – 60 kHz, -3 dB.<\/p>\n

                  Peak Output Current:<\/strong>
                  \n>45 Amps<\/p>\n

                  Dynamic Range:<\/strong>
                  \n117 dBA<\/p>\n

                  THD + Noise, 0.1W-500W\/4 ohm:<\/strong>
                  \n<.05%, typically .006 @ 1kHz.<\/p>\n

                  CCIF Intermodulation Distortion, 19\/20 kHz:<\/strong>
                  \n<.002%<\/p>\n

                  Damping Factor @ 1kHz:<\/strong>
                  \n275<\/p>\n

                  Overall Gain: (Balanced or Unbalanced)<\/strong>
                  \nSelectable Internal Jumper,
                  \n26 or 32 dB<\/p>\n

                  Input Impedance:<\/strong>
                  \n40k ohms<\/p>\n

                  Common Mode Rejection Ratio:<\/strong>
                  \n>90dB, 20 Hz – 20 kHz<\/p>\n

                  Absolute Phase:<\/strong>
                  \nNon-inverting, Pin 3 Positive<\/p>\n

                  Inputs:<\/strong>
                  \nUser Selectable,
                  \n2 x Balanced XLR
                  \n2 x Unbalanced RCA<\/p>\n

                  Outputs:<\/strong>
                  \n2 Pairs Parallel Binding Posts per Channel<\/p>\n

                  Power Consumption:<\/strong>
                  \nStandby Switch OFF 45 watts
                  \nStandby Switch ON (idle) 55 watts
                  \nMaximum 1200 watts<\/p>\n

                  Amplifier Weight:<\/strong>
                  \n95 lbs.\/43 kg.<\/p>\n

                  Shipping Container Dimensions:<\/strong>
                  \n27\u201d (L) x 21\u201d (W) x 16\u201d (H)
                  \n68 cm (L) x 54 cm (W) x 41 cm.<\/p>\n

                  Shipping Weight:<\/strong>
                  \n103 lbs.\/47 kg<\/p>\n

                  \n

                  Model 304 Features<\/h2>\n

                  XLR input connectors for balanced system configuration.<\/p>\n

                  RCA input connectors for unbalanced system configurations.<\/p>\n

                  User selectable switching between balanced and unbalanced connections.<\/p>\n

                  Transformer coupled inputs provide universal compatibility with other components and eliminate
                  \nground loop noise and EMI.<\/p>\n

                  Four channel capability allows use in multi-channel systems as well as providing four channels of
                  \ndiscreet amplification for multi-amped stereo systems.<\/p>\n

                  Ultra-high efficiency output section generates high power output with very little heat.<\/p>\n

                  Fully-balanced circuit topology implemented from input to output.<\/p>\n

                  Power Factor correction in power supply reduces AC line harmonic noise pollution and increases
                  \nAC line power utilization to 99%.<\/p>\n

                  Proprietary switch-mode power supply technology ensures consistent performance under all
                  \noperating conditions.<\/p>\n

                  12V remote ON\/OFF remote power switching via 1\/8\u201d jack on rear panel.<\/p>\n

                  CE approved speaker output terminals require no tools for secure, low resistance connections.<\/p>\n

                  Standby power mode reduces warm-up time.<\/p>\n

                  Fail-safe operation provided by user-resetable thermal circuit breaker located on rear panel.<\/p>\n

                  Quiet, transient-free operation during power ON\/OFF and input configuration switching.<\/p>\n

                  Selectable overall gain of 26 or 32 dB.<\/p>\n

                  Ultra-low resonance, structurally rigid chassis constructed of precision-machined aircraft grade
                  \n6061-T6 aluminum.<\/p>\n

                  3-point self-leveling chassis support.<\/p>\n

                  Model 304 Technical Specifications<\/h2>\n

                  Output Power: Continuous RMS watts, all channels driven<\/strong>
                  \n@ 8 ohms 300 watts
                  \n@ 4 ohms 500 watts<\/p>\n

                  Power Bandwidth:<\/strong>
                  \n5 Hz – 60 kHz, -3 dB.<\/p>\n

                  Peak Output Current:<\/strong>
                  \n>45 Amps.<\/p>\n

                  Dynamic Range:<\/strong>
                  \n117 dBA.<\/p>\n

                  THD + Noise, 0.1W-500W\/4 ohm:<\/strong>
                  \n<.05%
                  \ntypically .006 @ 1kHz.<\/p>\n

                  CCIF Intermodulation Distortion, 19\/20 kHz:<\/strong>
                  \n<.002%.<\/p>\n

                  Damping Factor @ 1kHz:<\/strong>
                  \n275.<\/p>\n

                  Overall Gain: (Balanced or Unbalanced)<\/strong>
                  \nSelectable Internal Jumper, 26 or 32 dB.<\/p>\n

                  Input Impedance:<\/strong>
                  \n40k ohms.<\/p>\n

                  Common Mode Rejection Ratio:<\/strong>
                  \n>90dB, 20 Hz – 20 kHz<\/p>\n

                  Absolute Phase:<\/strong>
                  \nNon-inverting, Pin 3 Positive.<\/p>\n

                  Inputs:<\/strong>
                  \nUser Selectable
                  \n4 x Balanced XLR
                  \n4 x Unbalanced RCA.<\/p>\n

                  Outputs:<\/strong>
                  \n1 Pair Binding Posts per Channel.<\/p>\n

                  Power Consumption:<\/strong>
                  \nStandby Switch OFF 45 watts.
                  \nStandby Switch ON (idle) \u00a055 watts.
                  \nMaximum\u00a01200 watts.<\/p>\n

                  Amplifier Weight:<\/strong>
                  \n95 lbs.\/43 kg.<\/p>\n

                  Shipping Container Dimensions:<\/strong>
                  \n27\u201d (L) x 21\u201d (W) x 16\u201d (H)
                  \n68 cm (L) x 54 cm (W) x 41 cm.<\/p>\n

                  Shipping Weight:<\/strong>
                  \n103 lbs.\/47 kg.<\/p>\n

                  \n

                  Model 312 Features<\/h2>\n

                  XLR input connectors for balanced system configuration.<\/p>\n

                  RCA input connectors for unbalanced system configurations.<\/p>\n

                  Dual Speaker Output Terminals on each channel for bi-wiring applications.<\/p>\n

                  User selectable switching between balanced and unbalanced connections.<\/p>\n

                  Transformer coupled inputs provide universal compatibility with other components and eliminate ground loop noise and EMI.<\/p>\n

                  High efficiency ICEpower\u00ae power conversion technology generates high output power with very little heat.<\/p>\n

                  Fully-balanced topology implemented in both input and output circuitry.<\/p>\n

                  Power Factor Correction (PFC) in power supply reduces AC line harmonic noise pollution and increases AC line power utilization to 99%.<\/p>\n

                  Proprietary switch-mode power supply technology ensures consistent performance under all operating conditions.<\/p>\n

                  12V remote ON\/OFF remote power switching via 1\/8\u201d jack on rear panel.<\/p>\n

                  Standby power mode reduces warm-up time.<\/p>\n

                  CE approved speaker output terminals require no tools for secure, low resistance connections.<\/p>\n

                  Fail-safe operation provided by user-resetable thermal circuit breaker located on rear panel.<\/p>\n

                  Quiet, transient-free operation during power ON\/OFF and input configuration switching.<\/p>\n

                  Selectable overall gain of 26 or 32 dB.<\/p>\n

                  Ultra-low resonance, structurally rigid chassis, precision-machined from a solid block of aircraft grade 6061-T6 aluminum.<\/p>\n

                  3-point self-leveling chassis support.<\/p>\n

                  Model 312 Technical Specifications<\/h2>\n

                  Output Power, Continuous RMS watts, both channels driven<\/strong>
                  \n500 watts @ 8 ohms
                  \n1000 watts @ 4 ohms<\/p>\n

                  Frequency Response<\/strong>
                  \n5 Hz \u2013 45 kHz, -3 dB @ 8 ohms<\/p>\n

                  Peak Output Current<\/strong>
                  \n40 amps<\/p>\n

                  Dynamic Range<\/strong>
                  \n120 dBa<\/p>\n

                  Load Impedance Range<\/strong>
                  \n2 ohms \u2013 16 ohms<\/p>\n

                  Input Impedance<\/strong>
                  \n40k ohms<\/p>\n

                  THD + Noise, 0.1 watts \u2013 500 watts, 4 ohms<\/strong>
                  \n< 0.1%, Typically .01% @ 1 kHz<\/p>\n

                  CCIF Intermodulation Distortion, 19\/20 kHz<\/strong>
                  \n< .002%<\/p>\n

                  Damping Factor @ 1 kHz<\/strong>
                  \n> 1000<\/p>\n

                  Overall Gain (Balanced or Unbalanced)<\/strong>
                  \nSelectable Internal Jumper
                  \n26 or 32 dB<\/p>\n

                  Common Mode Rejection Ratio<\/strong>
                  \n> 90 dB, 20 Hz \u2013 20 kHz<\/p>\n

                  Absolute Phase<\/strong>
                  \nNon-inverting, Pin 2 Positive<\/p>\n

                  Inputs<\/strong>
                  \n2 Balanced (XLR), 2 Unbalanced (RCA) (user selectable)<\/p>\n

                  Outputs<\/strong>
                  \n2 pair Parallel Binding Posts per channel<\/p>\n

                  Power Consumption<\/strong>
                  \nIdle \u2013 35 watts
                  \nMaximum \u2013 2000 watts<\/p>\n

                  Amplifier Weight<\/strong>
                  \n70 lbs. \/ 32 kg Amplifier<\/p>\n

                  Shipping Weight<\/strong>
                  \n83 lbs. \/ 38 kg Overall<\/p>\n

                  Amplifier Dimensions (H) x (W) x (D)<\/strong>
                  \n10.5\u201d x 15.5\u201d x 18.3\u201d
                  \n267mm x 394mm x 465mm<\/p>\n

                  More Jeff Rowland<\/h2>\n

                  Jeff Rowland Company Special Main Page
                  \n<\/a>                  Jeff Rowland Company Special Power Amplifiers
                  \n<\/a>                  Class AB vs Class D – Model 525 compared to Model 201, Model 10 and Model 6
                  \n<\/a>                  Trends TA-10.2, Wadia 151, Jeff Rowland 102 and OEM ICE Power module compared<\/a><\/p>\n

                  Also Read<\/h2>\n

                  “Digital” Switching Class D or Class T Amplifiers<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

                  Model 302 2002-2009 Retail prices in 2007 in Germany: Model 302 2 x 300 W – ICE-Pack-Amp \u00a017.398,00 Model 302-handles 2 x 300 W – as above, with handles\u00a0 17.998,00 Model 302\/4 – 2 x 300 W – 4-Module-Amp for\u00a0Bi-amping. \u00a018.698,00 Model 302\/4-handles – 2 x 300 W – as above, with handles 19.398,00 Rowland’s […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":8319,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-9544","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/pages\/9544","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/comments?post=9544"}],"version-history":[{"count":8,"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/pages\/9544\/revisions"}],"predecessor-version":[{"id":9837,"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/pages\/9544\/revisions\/9837"}],"up":[{"embeddable":true,"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/pages\/8319"}],"wp:attachment":[{"href":"https:\/\/www.hifi-advice.com\/blog\/wp-json\/wp\/v2\/media?parent=9544"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}