The Hafler DH-222 Bridging Kit is available to enable conversion of the DH-220 into a high power monophonic amplifier, bridging the two conventional channels into a single floating output which can deliver in excess of 400 watts into an 8 ohm load. Its rated power output is 350 watts across the audio band.A Stereo Power Amplifier available ready built or as a kit. Intended for 120 V AC 60Hz in the USA, for use in other countries a multi-voltage power transformer is available at extra cost for 100, 110, 120, 200, 220 and 240 volts 50 or 60 cycle AC mains.I have access to literally hundreds of thousands of Obsolete User Manuals, Lots of Repair Manuals, Service Manuals, Rare Schematic Diagrams, PDF Books, How to Repair Manuals, Lost Operating Manuals, Old Handbooks, Lost Parts Lists, Hidden Service Bulletins, Informative Repair Tips, Complete Disassembly Routines, and Much, Much, More!. I carefully scan and arrange each document into a downloadable and printable PDF FILE of high quality. It will take me years to scan and create all of the files I have access to. So if you use the search feature on our website and do not find your document simply use the Contact Form and ask for your document. More than likely I will have it. I will quickly scan and upload the file and then send you back a link so you can purchase.There was a time when my good friend Luigi was bringing HiFi gear by our house for testing on a regular basis. And although there were lots of interesting discoveries to be made, somehow the devices did not strike a chord with us to the extent that we actually wanted to own them. One day, as I was climbing up the staircase from an evening teaching classes, I could hear music playing in the living room that sounded very realistic, even from a distance. Whatever this is, I was thinking to myself taking the last few steps, this is going stay. The system Luigi had set up for us was a Hafler combo consisting of the DH-110 preamplifier and the 60 watts DH-120 power amplifier. And its musicality was beyond anything we had heard at the time. When I later asked my wife at which point she knew that this would stay, she said that she had already heard it was very special from the kitchen – which is about thirty feet down the hall.
We gave the Citation a final listen and then hooked up the DH-220 for comparison. The improvement in this scenario was immediately audible even though the amp was still warming up. The slight dreaminess of the Citation was gone, music now had a more intense and realistic dimension to it which became especially striking when playing live recordings. Whereas the Citation had caressed the listener, the Hafler had a straightness and insistence to it that was familiar to me from some Quad amplifiers. The DH-220’s midrange is tonally very accurate and at that pleasingly broad. Its bass lines are powerful and controlled which develops into a pleasing fullness of sound. Spatial representation is highly accurate and piano notes are flung deep into the room. The Halfer played so well that we were able to remove the weights that I had placed on top of each speaker for better imaging and could pull the speakers further into the room without losing foundation. We will certainly keep this amp around for a while to enjoy the new dimension in sound. The Hafler DH-220 is well worth exploring. Wherever this amplifier fits in, it is going to be very hard to beat.From my own experience I know that the DH-220 can be quite a princess, in the sense that it does not play with everybody. Some time ago we had borrowed it from Luigi to test it on our smaller system. In this scenario it had to play with some mediocre preamp and mid-fi speakers. The result was less than pleasing, and we soon returned the amp to look for something more appropriate. I was therefore surprised when Luigi insisted that I give this amp a second chance, now that all our other components had gradually been upgraded. In the current scenario the DH-220 was to replace the Citation Twelve Deluxe, a power amp that we have come to enjoy. And the playing partners were a Lenco L75 turntable, the Restek V1 pre, and Tannoy DC6t speakers at 8 ohms.
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’ i.e. that ‘forced detail’ sound you probably know too well. With a laser focus we fashioned a new path to a new level of excellence.The planning and hoped for results with any of our mods will depend, to some degree, on the underlying health of the original amp. Consider these helpful improvements.Because MOSFETs are very easy to drive a traditional higher current driver is not required so a simpler Class-A transconductance stage can do a great job. We use high-performance low capacitance video transistors. Also since MOSFETS don’t experience ‘thermal runaway’ there is no need for volt-amp limiting circuitry further simplifying the design and enhancing clarity. Your ears will agree that ‘simple is good’.Okay all you guys who bought PA-7s please calm down. PA-8, for Hafler DH-200, DH-220, XL-280, is a physically larger PA-7 with directly mounted power mosfets.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 PA-8), P225, P230 and so on. The kit prices will be unchanged, but some of the amps require more labor, i.e. installed prices go up. Other modifications touted for the home versions work quite well. At present our instructions are more tuned for the home versions of amps.
The PA-6 is an enhanced, effective tweaked-by-ear amplifier circuit An enhanced front-end power supply design, called CRC, inherited from PA-5 series with four front-end power supply caps provides a much cleaner, quieter voltage for the critical front-end circuitry.Superb high-end audio grade caps are used in the feedback loop and front-end power supply positions on the PA-6 Elite for higher resolution, crystal-clear frequency extension, clarity and just plain naturalness. See Ultra build details in full mod description below. These kits includes additional installation parts including hookup wire, solder, capacitors, etc.