Juma Amplifier

With Juma, we set new standards for quality, craftsmanship and creativity in guitar amplification.

First, you see it.  A glowing deep purple wood with a glossy finish.  Your interest peaks.  You get closer.  Aahhh, tea stained hemp fabric covering two 12 inch speakers.  You touch the case.  Your heart is racing.  What could be under this lid labeled Juma?  You unlatch the fasteners that you've never seen in your life.  You lift the lid off and there it is.  Two shining chrome chassis, six tubes, three knobs, three cylinders covering transformers, all set on top of a carved out, solid aluminum block.  You turn the first knob.  A heavy, gliding click into 24 positions of separately set resistors for volume, trebel and bass.  The tubes start to glow, yet you still hear nothing.  Is it really on?  Then you play.  The sweetness that you feel from this work of art, is now pouring your notes across the room.  You start to tweak the knobs.  The beast starts growling.  You are in control.  Or is it taking on a life of its own?  You then decide that you will never regret your decision to bring one of these masterpieces into your home.

Juma Details

The Juma amplifier is a single ended amplifier with three power tubes in parallel.  Output power ranges from 18 to 36 watts depending on what power tubes you install.  There are no electronic adjustments to be made for tube swaps, this enables you to try many different combinations of power tubes.  6V6, 6L6, KT66, KT88, 6550, 7581 and EL34's to mention some of the more common power tubes that can be used.  You are not limited to using all the same tube either, you can mix and match for endless tonal colours.

There are three controls on the Juma ;  Volume, Treble and Bass.  Pre-amplifier tubes can also be swapped for different tones as well.  The rectifier tube controls the touch responsiveness of the amplifier and that too can be swapped for many different feelings.

The Juma is constructed with top quality parts in a point to point manner with .999 fine Silver wire.

The concept of using two chassis is to isolate 60 Hz AC hum from the audio section.     The Power Chassis takes in AC  or Alternating Current from the wall.  This carries with it a 60 hz hum.  The AC is then converted to DC or Direct Current.  The power is then run cleanly through a shielded umbilical cord to the Audio Chassis. By running everything in the Audio section on DC, we eliminate the hum interference from the speakers.

The Juma amplifier is separated from the speaker cabinet with isolation cones.  To minimize speaker vibrations to the amplifier.  The speaker cabinet houses a pair of 12" Celestion Alnico Blue  'Bulldogs'.  We used Alnico for its musical attributes.  The speaker enclosure is sealed and damped for lower end extension.

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Read 3585 times Last modified on Thursday, 27 February 2014 04:34
Published in Mill Hill Gear
Jonathan Edward Glynn

Jonathan Glynn has professional electronic training from Air Force, Military Contracts and Motorola as well as self-education.

Website: www.millhillaudio.com

CONTACT: Jonathan Glynn | 805.415.9878 | California, USA | Jonathan@MillHillAudio.com