RD AUDIO TRANSFORMERS

SIMPLE TECHNOLOGIES  .... BETTER SOUND QUALITY

 

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since 24-3-2006

Royal Device AUDIO  TRANSFORMERS

The Royal Device HIGH QUALITY industrial standard Audio signal transformers have been expecially designed for audio applications into the BLU EYES 20 - 30 - 50 - MONOBLOCK - BLU BAY and BLU SKY series  AMP INTERSTAGE SECTION and for the  BLU EYES 3 - 5 PREAMPLIFIER, RUBINA 3, RUBINA EVOLUZIONE and RUBINA RIVOLUZIONE phono STAGE series where they are either used as INTERSTAGE section for ACTIVE TONE CONTROL without the use of any type of FeedBack neither any voltage amplifying stage.

Last but not the least is the application in interstage coupling and output stages of all the CD Players MODIFICATION boards.

Of course, all transformers are designed for the application they are applied to.

Many transformer are assembled with dual windings on the primary and on the secondary providing a wide range of impedance matching for the Blu EYES series as input, interstage and ouptput applications.

RD also design all the OUTPUT POWER transformers for the Blu EYES and BLU BAY power amplifiers.

 

All transformers are designed and produced by  Royal Device. All frequency and transient response details are shown hereafter:

 

Royal Device signal transformers

Dimensions: L 34 x d 28 x h 27,5

 

 

 

 

RD 15-101S

primary/secondary:  1+1:1+1 (nominals)

primary nominal impedance: 75+75 ohm

secondary nominal impedance: 75+75 ohm

frequency response: 10 Hz-100 KHz (+/- 0,1 dB) on 2K2ohm load

-3 dB @ 430 KHz

phase response (dotted line):

20 Hz-20 KHz (+8,9° /-4,2°)

STEP Response: 0.8 microseconds - Test voltage 10 KHz 2 Vpp square wave -  5 Vpp output

 

 

 

 

 

 

 

 

 

RD 15-102S

primary/secondary:  1+1:2+2 (nominal)

primary nominal impedance: 75+75 ohm

secondary nominal impedance: 300+300 ohm

frequency response: 10 Hz-60 KHz (+/- 0.5 dB) on 3K9ohm load

- 1.3 dB @ 100 KHz

-3 dB @180 KHz

phase response (dotted line):

20 Hz-20 KHz (+9.2° /-10,2°)

STEP Response: 2.3 microseconds - Test voltage 10 KHz 2.5 Vpp square wave -  5 Vpp output

 

 

 

 

 

 

 
 

RD 15-4

primary/secondary:  1+1 : 8+8 (nominal)   1:8 / 1:16

primary nominal impedance: 9 + 9 ohm

secondary nominal impedance: 600 - 600 ohm

frequency response: 19 Hz-200 KHz (+/- 1 dB) - load 1K5 ohm

16 Hz - 225 KHz  -3 dB   (parallel-parallel)

Pahse response (dotted line):

20Hz - 20KHz (+4,9° / - 5,6°)

PRIMARY coils IN PARALLEL mode- SECONDARY coils IN PARALLEL mode - X 8,5 (18,6 dB)

PRIMARY coils IN PARALLEL mode - SECONDARY IN SERIES mode - X 17,8 (25 dB)

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PRIMARY coils IN PARALLEL mode- SECONDARY coils IN PARALLEL mode - X 8,5 (18,6 dB)

SQUARE WAVE RESPONSE: 1,5 microseconds - square wave 10 KHz 0,5Vpp (red trace)- OUTPUT 5 Vpp (blue trace) - PRIMARY IN PARALLEL mode - SECONDARY IN PARALLEL MODE - X 8,5 (18,6 dB) LOAD 1,5 Kohm

PRIMARY  IN SERIES mode - SECONDARY IN SERIES mode - X 8,5 (18,6 dB)

 frequency response: 9 Hz- 70 KHz (+/- 1 dB) - load 2K49 ohm

 

PRIMARY IN SERIES MODE - SECONDARY IN PARALLEL MODE - X 4,6 (13,2 dB)

frequency response:: 9 Hz- 205 KHz (+/- 1 dB) - LOAD 820 ohm

 
 

RD 15-6

primary/secondary:  1+1 : 7+7 (nominal) - 1:7 / 1:14

primary nominal impedance: 15+15 ohm

secondary nominal impedance: 700 - 700 ohm

frequency response: 12 Hz-230 KHz (+/- 1 dB) - load 2K2 ohm

-3 dB @ 250 KHz (parallel-parallel)

phase response (dotted line):

20Hz - 20KHz (+ 3,5° / -3,8 °)

PRIMARY COILS IN PARALLEL MODE - SECONDARY COILS IN PARALLEL MODE - X 7,5 (17,5 dB)

 PRIMARY COILS IN PARALLEL MODE - SECONDARY COILS IN SERIES MODE - X 14,6 (23,3 dB)

 

 

PRIMARY COILS IN PARALLEL MODE - SECONDARY COILS IN PARALLEL MODE - X 7,5 (17,5 dB)

 SQUARE WAVE RESPONSE: 1,1 microseconds - square wave 10 KHz 0,6Vpp (red trace)- OUTPUT 5,2 Vpp (blue trace)

PRIMARY COILS IN PARALLEL MODE - SECONDARY COILS IN PARALLEL MODE - X 7,5 (17,5 dB)

 PRIMARY COILS IN PARALLEL MODE - SECONDARY COILS IN SERIES MODE - X 14,6 (23,3 dB)

FREQUENCY RESPONSE: 16 Hz-86 KHz (+/- 1 dB) - LOAD 3K3 ohm
 

 

RD 15-3A

primary/secondary:  1:3+3 (nominals)

primary nominal impedance: 75 ohm

secondary nominal impedance: 675+675 ohm

frequency response: 10 Hz-60 KHz (+/- 0.5 dB) on 3K ohm load

-3 dB @ 80 KHz

phase response (dotted line):

20 Hz-20 KHz (+21.3° /-15,7°)

STEP Response: 4.8 microseconds - Test voltage 10 KHz 3 Vpp square wave -  10 Vpp output

 

 

 

 

 

RD 15-104S

primary/secondary:  1+1:1+1 (nominals)

primary nominal impedance: 300+300 ohm

secondary nominal impedance: 300+300 ohm

frequency response: 10 Hz-100 KHz (+/- 0,15 dB) on 3K9ohm load

-0.7 dB @ 100 KHz

-3 dB @ 170 KHz

phase response (dotted line):

20 Hz-20 KHz (+5.2° /-10,2°)

STEP Response: 2.4 microseconds - Test voltage 10 KHz 2 Vpp square wave -  2.5 Vpp output

 

 

 

 

 

 

 
 

 

RD 15-4B -41

primary/secondary:  1:4+4 (nominals)

primary nominal impedance: 35 ohm

secondary nominal impedance: 600+600 ohm

frequency response: 10 Hz-80 KHz (+/- 0.5 dB) on 2K7 ohm load

-3 dB @ 100 KHz

phase response (dotted line):

20 Hz-20 KHz (+16,4° / - 14,8°)

STEP Response: 3.6 microseconds - Test voltage 10 KHz 1 Vpp square wave -  4.6 Vpp output

 

 

 

 
 

 

RD 15-4B -45

primary/secondary:  1:4,5+4,5 (nominals)

primary nominal impedance: 30 ohm

secondary nominal impedance: 600+600 ohm

frequency response: 10 Hz-60 KHz (+/- 0.5 dB) on 2K7 ohm load

-3 dB @ 88 KHz

phase response (dotted line):

20 Hz-20 KHz (+22,3° / - 18,8°)

STEP Response: 3.8 microseconds - Test voltage 10 KHz 1 Vpp square wave -  5.2 Vpp output

 

 

 
 

 

RD 15-5

primary/secondary:  1:5+5 (nominals)

primary nominal impedance: 35 ohm

secondary nominal impedance: 800+800 ohm

frequency response: 10 Hz-50 KHz (+/- 0.5 dB) on 3K ohm load

-3 dB @ 70 KHz

phase response (dotted line):

20 Hz-20 KHz (+19,9° / - 22,3°)

STEP Response: 3.8 microseconds - Test voltage 10 KHz 0.9 Vpp square wave -  5 Vpp output

 

 

 
 

 

RD 15-105S

primary/secondary:  1:1.5+1.5 (nominals)

primary nominal impedance: 75 ohm

secondary nominal impedance: 150+150 ohm

frequency response: 20 Hz-100 KHz (+/- 0.1 dB) on 1K8 ohm load

-3 dB @ 170 KHz

phase response (dotted line):

20 Hz-20 KHz (+7,8° / - 8,7°)

STEP Response: 2.3 microseconds - Test voltage 10 KHz 2.7 Vpp square wave -  5 Vpp output

 

 

 

 

 

 
 

RD 15-106S

primary/secondary:  1+1 : 6.5+6.5 (nominals)

primary nominal impedance: 75 + 75 ohm

secondary nominal impedance: 3 K + 3 K ohm

frequency response: 20 Hz-40 KHz (+/- 0.25 dB) on 15K ohm load

-3 dB @ 63 KHz

STEP Response: 5.6 microseconds - Test voltage 10 KHz 0.7 Vpp square wave -  5 Vpp output

 

 

 

 

 

 
 

 

RD 30-101S

primary/secondary:  1+1:1+1 (nominals)

primary nominal impedance: 50+50 ohm

secondary nominal impedance: 50+50 ohm

frequency response: 5 Hz-200 KHz (+/- 0,1 dB) on 2K2ohm load

-3 dB @ 12 Hz  - 430 KHz

phase response (dotted line):

20 Hz-20 KHz (+11° /-4,3°)

STEP Response: 0.76 microseconds - Test voltage 10 KHz 9 Vpp square wave -  10 Vpp output

 

 

 

 
 

The  figure beside shows the phase response at open loop of the Burr Brown Operational Amplifier  OPA 2604 that features a 0 dB bandwidth up to  20 MHz, one of the many used into the Hi-Fi applications (CDP outputs, amplifier inputs etc.)

It can be clearly seen that already from 100 Hz up to 2000 Hz (red arrows), phase response vary up to 75°.

This means that a tough delay exist between input and output in the more important range of the audio band, introducing distortion when feed back will be applied. This means also annoying material be introduced in terms of sound reproduction.

A lot of intemodulation and temporal distortion will be generated when Feed back will be applied, because the delay is very important when there is a relationship between output and input.

What does it mean to have a 100dB amplification, when maybe needed a 20 dBs or so and apply a 80 dB Feed back to make the amplifier  usable?

A transformer, gives the right gain without introducing intermodulation and temporal distortion because there is no relationship (feed back) between output and input.

And in Royal Device, we do not use any form of feed back at all.

 

OPERAZIONALE BURR BROWN OPA 2604
 

Here follows what can be achieved with 5 transformers using ONLY ONE VOLTAGE AMPLIFIER into the last stage (power amp) without using any form of feed back.

It can be possible to amplify from 0.2 millivolt (MC cartridge) up to 50-75 Watts channel and over with more than 30 possibilities of adapting the amp output to the load even in a SIMIL B-AMP manner.

 

 

 

 BE 51 output 50 watts transformer
 

 

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