Hafler DH-200- modded or not?

[wizargoz]

I bought a near mint Hafler DH-200 from a Craigslist seller for $25 (not that I needed another power amp), and plugged it into my system. I was using Soundcraftsmen pieces (A-2502 power amp (swapped for the DH-200) and SP-4002 pre-amp) driving 2 pair of Klipsch Cornwalls, which sounded quite good. The Hafler, however, sounded cleaner(?), a bit punchier and more articulate (don't know if I'm describing this well). It just sounded better- not profoundly, but noticeably, better.
I have the DH-200 manual PDF file, though I don't see any instructions about removing the cover. A lot of screws in the sides in the heat sinks. I know that the Hafler's gained significant musicality after being modded- so if I do take the cover off, what would I be looking for? I added the PDF pic of the original Hafler as a reference.

 

[dshoaf]

Post a pic of the innards of yours. The cover comes off with a series of small sheet metal screws located in the heat sink fins.

If this has been a kit-built version, the folks here will be able to tell. Sometimes it can be difficult to determine if the unit has been modded or just kit built.

Yes, these can sound quite good but to really get to the next level of performance, you'll need to replace the entire driver boards. Outside of that, I'd recommend that the old electrolytics be replaced for sure.

Hope that helps.

Cheers,

David

 

[avionic]

MOSFETS ? I like MOSFET's.....

 

[himm37]

I've had my DH-500 since I built it in 1981! Finally lost a channel a year or so ago, I think it was lightning. I moved on to tubes, and don't see myself ever looking back, but one of these days I'm going to restore/upgrade my old friend!

When I got into the 5.1 phase, I bought an extra 500 and a 220, that I put a bridge switch in. When I ran all 3 and my 56 HD rear projector set, I could see my electric bill go up about $50.00 a month! When The 500 died, I unbridged the 220 and used it for my main amp, I actually think it sounded better then the 500, warmer would be the way to describe it. These amps are "giant killers" stock IMHO, and when modded correctly are supposed to be hard to beat.

 

[Blue Shadow]

The top comes off with the top screws in each column along the heat sinks. The bottom screws in each stack are for the bottom of the unit. The silver screw in the center is not to be removed to remove the top. Four screws per side. The top may come up more easily if you push down on the heat sinks a bit to spread them a bit.

Nice clean amps. I have two that I built years ago. These amps have a couple issues that are known by the techs. Like if there is some kind of short, it blows a resistor which is fairly easy to replace. The DC offset may be off. One AKer swapped the predriver transistors to correct this but it didn't and when he changed the electrolytic caps, all was good. Great sounding inexpensive amps.

They can be upgraded by musical concepts for $$$. Makes em world class to hear folks talk about that. Quite a bit about them hear at AK.