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Modding Hafler Amps?

Hi all. I've been away from the boards here for about a year, but I've got the audio bug...again.

The power switch on my Hafler DH-500 broke last month, giving me the lame excuse I needed to fork out the bucks to have it modded. An internet search found not only John Hillig (Musical Concepts), who I already knew about, but also Van Alstine. Has anyone compared the mods to recommend which company I should use to mod the amp? I'm not looking for all the exotic stuff- I just want the most bang for my buck.

Then the next problem: I also have a McCormack .5 amp (Rev A) that I love with my McCormack RLD-1. I could do a number of things - bi amp using both amps (Hafler for bass and McCormack for mid/high), toss the .5 (which I'd hate to do) and use either the Hafler by itself or purchase another used Hafler 500 and have it modded as well for biamping.

I can't really assess power needs right now, as I won't upgrade to speakers that really need the Hafler's power for another year, and I have no idea what speakers I'll buy. I'm thinking if I have more power than I need, no problem. Some day I'll probably want/need all that power, even if not in the near future.

Sorry this is so long, but thanks in advance for your advice!

aggielaw
sean
6,231 posts
 
Van Alstine probably has a greater degree of design experience although he is just learning about the differences in passive parts ( caps, resistors, etc... ). Hillig has probably modified WAY more gear but has more experience with the various sonic attributes of the passive parts that one would normally work with when modding gear. Only thing is, John may not have the technical design prowess that Frank has. So long as one is simply doing direct parts substitutions i.e. upgrading caps, etc.. Hillig may be the way to go. Then again and in your specific case, Van Alstine used to work directly with David Hafler ( if i remember correctly ) and may have greater insight into the actual design of these amps. Obviously, these are just my personal thoughts and ramblings, so take them for what they are worth. Sean
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jw94055
125 posts
 
Pooge. If you are a DIY type, you may want to get ahold of the POOGE articles from Audio Amateur.
himu's avatar
himu
6 posts
 
let me transform your DH500, 200, 220 etc. you will not be disappointed.
I can send you a modified one to listen too and you can
decide for yourself. There are many levels to mod too.

My major mod takes you way beyond pooging and passive part
replacement. I can explain all the mods if you care to
listen. The major requirement is a solid running amp
to start with!!! I can also repair if necessary.

Please feel free to ask questions I will try to explain.

Ralph
sean
6,231 posts
 
I guess i was "thinking inside the box" on that one. I agree with the others. That is, there are GOBS of info available about modifying these amps. Much of what either of these guys would do and charge a high hourly labor rate, you can do yourself. That is, it is simply a matter of unsoldering one part and replacing and resoldering with another higher grade part. That part could be capacitors, resistors, wiring, etc... There's nothing hard about doing something like this, but it can seem VERY scary at first. Just take your time and make notes along the way. Having a schematic and then looking at how the schematic equates to the actual parts layout on the board can help you with signal flow and what parts play key roles. Sean
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jw94055
125 posts
 
Something I should have mentioned in my original post. If they are not soldered in, VERY CAREFULLY remove each mosfet and clean the pins. Of all the things I did to improve the sound of my old DH 200, I don't think anything I did made as big a difference. I got that advice from some post on a Hafler user group site. P.S. I was satisfied with my Hafler until I got an original Son of Ampzilla. The Ampzilla is better in everyway.
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