Hafler
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Mods for Hafler DH-120, SE series and 9000 series

PA-3D Front-End Circuit Boards: for Hafler DH-200/220/500 and XL-280/600, plus we do some custom installations in other MOSFET amps.

THE DESIGN: Design simplicity has always been a trademark of Musical Concepts products. The new PA-3D is a straightforward, effective amplifier topology with a single-ended front-end. Now we have LED biasing of the current source in the differential 'front-end' to complement the original LED biasing in the driver stage. The DC offset control has been improved. Added space allows even larger power supply caps in the Platinum version. Some eyelets have been increased in size for easier wire insertion. The resistor outlines have been enlarged making conversion to the Platinum version upgrade easier and more attractive. The copper 'thickness' on the board has been increased by 50%, while we have reduced the 'trace' width in signal carrying areas for less 'bounce effect' from the board material. 

THE SOUND: Forget all the new technical improvements, the sound quality is the real treat. The degree of perceived dynamic range, bass power and overall delicacy is astonishing. Yet, there is a tremendous sense of effortless power. The delicacy, liquidity and naturalness make you think you are listening to a vacuum tube amp. Then along comes bass detail and overall clarity that makes you reconsider that thought. There is a sense of majesty and air-moving power that must be heard. PA-3D modified Hafler amps will honestly compare to the finest sounding amplifiers available today.

Attention kit builders --- you must set the output stage bias current with a multimeter (digital type with 2 Amps DC or more capability preferred). Then you set the DC offset voltage at the speaker outputs.

PA-3D modification
  $329 kit, $459.00 installed - kit includes all items shown including specially alloyed eutectic solder. 

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PA-3D Signature 
$479 kit*, $659.00 installed
Incomparable BlackGate® caps (FB and current source) for higher resolution, clarity and just plain naturalness, IXYS or Schottky Rectifiers for great bass, smoothness and that same word naturalness that keeps coming up. We use additional power supply bypass capacitors for superior resolution from top to bottom and a taut, resolved bass quality.
*kit is for a more experienced modifier

PA-3D Platinum
$1299 kit*, $1599.00 installed 
This exotic modification includes all Signature mods, plus about 50 exotic Platinum-Grade resistors, Cardas Copper Binding Posts, exotic OFC RCA jacks, additional PS bypass caps. See some of these items on Components page, see the RCAs and binding posts on our Connectors page. Our latest PA-3D Platinum is truly a superb amp that demands comparison to any amp available!
*kit is for a more experienced modifier

PA-3D Platinum Ultra
$2995 installed only for DH-200/220 & XL-280, $3195 for DH-500, $3395 FOR XL-600 
Our magnificent, incomparable PA-3D Platinum Ultra mod is truly State of the Art and beyond State of the Art as it is practiced by so-called high-end manufacturers. Although we at Musical Concepts have modified many expensive well known amplifiers we've never seen build quality even remotely close to the Ultra. Just imagine, if you dare, what this incomparable product might sell for if it had some fancy over-hyped manufacturer's name on the front panel. Consider that the Platinum Ultra has all the mods included with the Platinum mod plus far more. The DH-200/220 and XL-280 has a 625W dual secondary toroid power transformer. The main power supply is dual-mono with four large BlackGate® caps which are the finest you can buy for power supply applications. The DH-500 and XL-600 have twin 500W toroid power transformers and four BlackGate® main filter caps which supply totally dual-mono operation. Since the original Platinum Ultra was offered we have added the BlackGate FK 100uF/100V caps to the front-end power supply. At the new price we also include a new high in-rush current power switch and an IEC power cord socket with hi-current cord.

• Resistors: 1% Metal Film Resistors, Platinum Grade TaN resistors for Platinum version

• Circuit Board Material: Highest quality FR-4, G-10, mil-spec, dual-sided, 'plate-thru' circuit board with 3 ounce copper (twice as thick as the foils in many so called "audiophile" designs)

• Capacitors: High Performance Film and Electrolytic caps, BlackGates® in FB and CS for all models except standard

• 1st. Stage: Very tightly Hand-matched differential transistor pair with LED biased current source

• Driver Stage: Class-A, Cascoded driver stage features LED biasing and Ultra-Linear connection

• Front-End Power Supply: 4.7 times more capacitance than the original Hafler circuit board design, BlackGate® for Platinum Ultra

• RCA Jacks: High Quality Gold-Plated with Teflon® insulation (OFC/Gold-plated with Platinum)

• Binding Posts: Cardas® Copper with Platinum version and Ultra, optional on other versions

• On-Board fuses allow removal of originals from chassis for even more 'mod room'

• Pre-assembled circuit boards - hand soldered with sonically superior eutectic alloy solder

• Sonically superior bypass caps, extra pair provided for XL-280 and XL-600, multiple bypasses for Signature and up

• Special Eutectic alloy solder provided in kit version too

• Up to 12ga wire can be used with 'hi-current' pcb eyelets

More Power Amplifier options:
TP-200 and TP-500 toroidal power transformers

LC-200/LC-500 replacement power supply caps

Comment: We are often asked if these dual-mono mods are "worth it". "I mean I can buy a more expensive amp and maybe I should go that way", says the customer. Well, stop and think about it! In the case of the smaller amps you have 108,000 microfarads of capacitance and a dual-wound toroid power transformer with twin bridge rectifiers. Now consider the larger amps! You have 156,000 microfarads, twin bridge rectifiers and twin toroid power transformers. These are items that don't come cheap. You would expect to pay much more than your outlay for these massive power supplies if you buy a new amplifier, period! Suddenly it becomes a "no-brainer"!

Dual-Mono Power Supply Conversions

Improve the transparency, focus, imaging, bass solidity and resolution abilities of your amplifier with the tried and true optimization of your power supply for a mono amplifier level of sonic results. The ability of the amplifier to sound more "together" and unstrained is greatly improved. 

$599 factory installed into DH-200/220, XL-280 - these include four of the LC-200 filter caps and one dual-wound TP-200 toroid power transformers plus all extra hardware and installation!!! 

$749 factory installed for DH-500/XL-600 - these include four of the LC-500 filter caps and twin TP-500 toroid power transformers plus all extra hardware and installation!!! To see a sample dual-mono installation in a DH-500 click here!

We install Cardas connectors and/or OFC RCA jacks into any amp stock or modified. See our "Connector" page for these hi-quality RCA jacks and binding posts!

Hafler LX Modification: for SE Series, DH-120, 9000 series amps - We do THX® Stuff, Too!