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Sugden Super Mod
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We can modify your vintage amplifier to suit your requirements

You might wish for different connectors (e.g. RCA in place of DIN sockets) or improve the electrical safety.
Maybe you love the look of your amplifier but want to take the sound to greater heights.
Whatever your requirement, contact us on 044 01905 821737 and we will advise.
The Sugden A21 mod discussed below is an example of what can be done.

Premium A21 modification

By popular request we can now offer a major modification service for your Sugden A21. This raises this lovely vintage amplifier
to much greater heights with a vastly improved sonic performance. Putting it on par with today's greats.  Many Sugden fans love
the wooden case and black and silver front panel but want that extra ounce of musical clarity and separation. After this mod, you
have it all!

See the features below:

New ripple free PSU Assembly,

 New Power Output and Rear Heatsink Assembly,

Inside view of a modified A21

Inside view of original A21

Rear view of the modified A21

Front view  of the modified A21

 

bulletWe have totally redesigned the output stage with a vastly improved pre-driver, VAS, and  complementary triple output.

Power Amplifier PCB

 
bulletFrequency response 10Hz to 100kHz.
bulletDistortion @ 1kHz and 10kHz. less than 0.005% THD at 15W rms
bulletMax Class A RMS output power per channel 20 W rms into 8 ohms
bulletUses specially chosen  high quality ROHS semiconductors and components (output devices 2SC5200 and 2SA1943)
bulletThe 'direct/normal' switch when set to 'direct', removes the tone control stage to allow you to use an alternative pre-amp.
(In the direct mode the volume control functions as normal, the balance and tone controls are bypassed.)
bulletTwo operating modes 'cool and 'hot' allow you to switch from class AB to  Class A* 
bulletThe class A section includes Improved DC feedback current stabilization  

 

bulletNew rear aluminium panel with extra large heat sinks and extra room for improved socket spacing

 
bulletFeatures:
bulletNormal/Direct switch to switch the Sugden tone control stage in or out
bulletClass A/B selector switch. This allows reduced heat dissipation (particularly useful in the summer months)
bulletHigh quality gold plated conformal** loudspeaker binding posts
bulletGold Plated RCA sockets for Radio, Aux and Phono inputs
bulletIEC Mains input with fused and DPST on-off switch
bulletTwo massive 0.7 oC/W heat sinks, one for each channel
bulletTwo single layer output stage PCBs nest between the heat sink shields

 

bulletTwin power supply (separate rectification,  smoothing and ripple reduction circuits for each output stage
bulletIn the case of the early serial number Sugden A21s a new Toroidal transformer is used  for reduced magnetic field and extra power handling
bulletThe preamplifier screening cover is split in two to allow easy service access. (See top left picture above) 

* The word 'mainly' is used to signify the grey areas in the A/B classification. A class B amplifier needs a small amount of bias to remove cross over distortion, so at very low signal
 levels the amplifier works in class A.  Class A amplifiers work in class A for signal currents up to the set class A current typically up to an amp or so, and then reverts to class B on larger current peaks.

** According to the  ROHS and LV directives the original 4mm loudspeaker sockets and 4mm banana plugs must not be used for loudspeaker connections on new equipment, due
 to exposed metal contacts and risk of electric shock.         

If you are interested in having your Sugden A21 or A51 converted please contact us on 044(0)1905 821737 for pricing and lead times.

 

 

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Last modified: September, 2011 15:23:31