Important thought!


The planning and hoped for results with any of our kit modifications will depend, to some degree, on the underlying health of the original amp not to mention your installation skills. Consider these helpful improvements.


Hafler Pro Amplifiers


We have given short shrift to these amps so let us begin to remedy that. The PA-XX series mods will work fine in Pro Series amps such as the P500(not our PA-8), P225, P230 and so on.

 

Pro-500 Package A: PA-7.3 Elite boards connected as a stereo amp, LC-500(30,000uF+ power supply cap pair) all installed $829


Pro-500 Package B: PA-7.3 Elite boards, your choice of power supplies(PS-500 V2B or PS-509 with 10-15KuF caps)

>>> Package B Requires removal of original unbalanced to balanced circuit board with both volume controls. Price depends on choices.


PRO-500 modifications will be installed with one pair of RCA gold jacks retaining one pair of original 1/4” jacks. Our kit instructions are aimed at home versions.


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PA-8 is here!


PA-8, for Hafler DH-200, DH-220, XL-280, is a physically larger PA-7 with directly mounted power mosfets.


PA-8 Features:



PA-8 Eliminates:



PA-8 is installed only for now. PA-8 has 12 new MOSFETS. Elite version is $899.00 installed, Ultra version is $1099 installed. Kit is coming, uh a little slowly.

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New PA-7.3 Hafler Driver Boards


The PA-7.3 is a new version of the PA-7 retaining the heart of the original but with sonic improvements and much simpler to install than the PA-7 V2.  Kit and installed versions are ready.

Elite driver boards are now ready to install into Hafler DH-200/220, XL-280, DH-500 and XL-600 amps.


PA-7.3 - Vision for excellence >Proper image to be added soon!


The Design: Our designer John Hillig has refined the PA-XX series modifications over many years. This research created new circuitry enhancing clarity and transparency without brightness or ‘etching’. You know that ‘forced detail’ sound you probably know too well with ‘high-end’ gear. With a laser focus we fashioned a new path to a new level of excellence.



The PA-7.3 is a tweaked-by-ear amplifier circuit. MOSFETs, the OEM Hafler output devices, are very easy to drive. A traditional higher current, Class-B driver stage, is not required resulting in a simpler Class-A transconductance stage(VAS) which does a great job. We used wideband video transistors for their minimal loading of the input stage. They also need only a minimum of compensation.





The PA-7.3 Sound: This is no mere Hafler. No, we don’t demean this great basic amp design which so many still love. Still the music lover ‘ear’ always wants more. PA-7.3 is a great amplifier in a Hafler chassis. Fidelity is big, not just a marketing term. You want to feel a connection to the vocalist and background vocalists too. You want to hear instruments in a striking, natural way. You want true tonal structure and timbral clarity of each instrument. Voices are clear, full-bodied and so intelligible that emotion is conveyed in the performances at a new level. You feel the mood, the intensity of the performer. Many will hear ‘new’ background vocals singing along with the lead vocal or the multi-layered vocals of the performer overdubbing ‘background’ vocals. There is a sense of gut solidity, simple majesty and air-moving power that must be heard. If your speakers play deep you’ll be thrilled. PA-7.3 amps will compare to the finest sounding amplifiers available today.



PA-7.3 New Highlights:



NOTE: (PA-7.3 photo to come soon)PA-7 kit shown has the PA-7 Ultra version boards featuring Audio Grade caps, premium resistors, more.  View the PA-7 kit installation instructions.


>>Information for kit builders. All of our front-end boards are fully tested in an actual power amp design. Settings for DC Offset and Bias are roughly dialed-in to test the function of these adjustable settings. <<



Options? Visit these pages - Amp Options  including maintenance suggestions, power supplies PS-200

See our "Connector" page for RCA jacks, binding posts, IEC sockets!




PA-7.3 Modification Range


NEW!  PA-7.3 Elite/Ultra Modification


Elite has great naturalness. The Elite version offers better imaging, focus and delicacy. Superb sounding caps are used in the and front-end power supply. Feedback loop has Audio-Grade caps on the PA-7 Elite for higher resolution, crystal-clear frequency extension, clarity and just plain naturalness.


Ultra adds near complete premium audio grade resistors array, superb front-end power supply caps.


These kits include: additional installation parts including hookup wire, solder, capacitors, etc.


>>Price Schedule<<


PA-7.3 Elite driver boards:  $529.00 kit, $679.00 installed - includes gold RCA jacks, other installation parts

PA-7.3 Ultra driver boards: $629.00 kit, $829.00 installed  - Kit or installed includes Premium RCA jacks


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 Budget choices


PA-6 Elite Modification Range - Reduced $ from original


  These kits includes additional installation parts including hookup wire, solder, capacitors, etc.


PA-6 Elite driver boards: $249.00 kit, $379.00 installed – while they last


PA-6 Ultra driver boards: $349.00 kit, $479.00 installed — while they last




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*PLUS UPGRADES FOR ALL PA-XX VERSIONS*


You not only want superior sound but extended reliability and confidence that you’re getting the best from your power amplifier. You want all this at a price that is unmatched considering the top quality of parts and sound. This more complete modification includes:


PA-XX Elite Driver Boards, pre-tested with all kit installation parts


You will receive a PS-220/500 power supply specialized for your amp, please specify your amp model when you order. See more PS-220/500 versions here, some of these items are on Exotic Parts page.


PA-XX Elite Plus for Hafler DH-200/220, XL-280 series amps:   Add $499.00* kit   -   $699.00* installed     

PA-XX Elite Plus for HaflerDH-500/XL-600 series amps:   Add $580.00* kit   -   $780.00* installed


 

OPTIONS FOR ALL PA-XXX VERSIONS


OPTIONS FOR DH-500, XL-600


PS-500M power supply , 8 premium 10KuF caps in CRC connection - add $100 to either kit or installed price above.


*For PA-7.3 Ultra driver boards add $250 to kit and installed pricing above.



Full PA-7.3 Ultra Modification

Our PA-7.3 Ultra mod is truly State of the Art and beyond State of the Art in sound as it is offered by so-called high-end manufacturers. Although we at Musical Concepts have modified many expensive well known amplifiers we've never seen build quality close to the Ultra. The superb resistors are used in nearly all slots for all Ultra driver boards. For all amps the Ultra also includes a new high in-rush current, silver-alloy power switch and a upscale IEC power cord socket with hi-current cord. Just imagine what this incomparable product might sell for if it had some fancy over-hyped manufacturers name on the front panel. This is the finest mod we have to offer.


PA-7.3 Ultra modification includes


Audio-Grade RCA Jacks - jewelry look, smooth, clear, solid sound

Audio-Grade Binding Posts - elegant rock solid connections, liquid sound - choose platings as available



PA-7.3 Ultra for DH-200/DH-220/XL-280/P225/P230:  $2550 installed only - add $100 labor for “PRO” amps


PA-7.3 Ultra for DH-500/XL-600:   $2895 Installed only - add $100 labor for PRO-500, consult for ‘noisy’ fan solution


>>>>Please Make Your Choice >>>  Keep or remove speaker fuse and output relay for more purity

Hafler Amplifier Modifications