Hafler DH200 Power Upgrade?

[gerryc]

OK, I have perused through the DH200 / DH220 threads here including the uber thread of about 695 posts! I'd like to ask a specific question about a reasonable power upgrade to a DH200, but couldn't find a direct answer to my question in these threads, so here goes.

Many years ago Walt Jung reviewed the DH200 in Audio Amateur magazine. In fact here's a link to the article:

http://www.nulltime.com/DIYAudio//pr...200review.html

Here's a quote from the article:

"... I measured outputs of over 130 watts (8 ohm) from both channels at the clipping level. Into 4 ohms I was able to get about 250 watts from a single channel! ..."

Now, knowing about the limitations of the power supply in these amps, this seems to imply that if the power supply was beefed up, either with a higher current transformer (maybe around 800VA) and possibly separate sets of windings for each channel one could possibly get 250 watts / 4 ohms with both channels driven, or 500 watts into 8 ohms bridged (these things were normally rated at 300 watts / 8 ohms bridged).

Has anyone done any such modifications / measurements that would verify that this is possible? I've seen where some have boosted the voltage to the driver stages as well but is this necessary to obtain these kind of power levels? I don't care about the lowest distortion since I'm interested in using this for musical instrument use. If I can do this relatively inexpensively (like around $100 or so) I'd do it, otherwise I'll just look for a used power amp that suits my needs. Thanks.

[Stormrider]

Leave the old Dh200 alone and buy a Pro audio amplifier if you need more power.

You could get another Dh200 and bridge each amp, but you could only use them for 8ohm loads.

[mlloyd1]

agreed. i would be concerned about high power into 4 ohm loads with just two pairs output mosfets while using almost 65v rails.
begging for trouble ....

mlloyd1

Originally posted by Stormrider
Leave the old Dh200 alone and buy a Pro audio amplifier if you need more power.

You could get another Dh200 and bridge each amp, but you could only use them for 8ohm loads.

[gerryc]

Yeah, I figured as much. If an upgrade were relatively straightforward and inexpensive then it would make sense, otherwise it makes more sense to put the money towards a proper amp for my needs. I'll have to say that the DH200 has been a great amp for home audio (I have another that I'm using on my stereo). I guess I'll just keep this as a backup or other uses. Thanks, guys.

[amp-guy]

you should at least upgrade the power supply caps, it makes a very noticable improvement, besides the originals are probably in need of replacement anyway.

[amp-guy]

O yeah bridging will give you around 350watts but quality degrades.