New Power Cable on a 1990 Hafler DH120?

Without gtting into the flat earth debates, i think it is clear to say that before spending money on a power cord, one should address the extensive known areas for improvement in that excellent design with budget parts. search for an get a copy of "pooge" by walt jung from the audio amateur and follow his list of upgrades, starting with bypassing signal chain electrolytic caps with itsy bitsy films.  jack up the bias.  clean all the contacts. replce the stamped metal RCAs (unless they improved those on the -220 over the -200 on whcih they sucked, that's a thechnical term.

Have fun. Cord will certainly cost more and do less.

Some think zero, others disagree.

eric makes another solid point.  The two large power supply capacitors, being 30 years old and electrolytic, probably only have about 1/3-1/2 of their original capacity.  Buy new drop-in replacements - the largest that you can fit into the band-clamps (in other words same form factor, same or higher voltage, biggest capacitance possible).  That will produce a staggering difference. The power cord, well.....

BTW Mr Decibel makes a reasonable point.  One area that, IMO, all components fall short is the quality of the connection to the wall AC.  This has two parts - the plug on your cord and the outlet in the wall. I routinely put in heavy duty outlets, and also replace the plugs with higher quality ones. You are looking for a tight connection and a large contact area.  The DH220 only draws about 1-1,5A most of the time and dynamics draw n the large filter caps, so the 14 agg cord diameter ought to be fine. On my much larger, vastly costlier amps i cannot really tell the difference between 14 and 12 guage. But i have good outlets, good plugs, power conditioning and massive power supplies int he amps. You can turn them off and they keep plying for a bit :-)

G

So, with a big, heatsinked 35 amp bridge i have put 1/4 Farad (eread that again, yes F) in a DH-200. and if you do blow it up its $3 online for a new bridge. So a giant "meh" to the worries.

That said the comments are true. There WILL be a bigger inrush. I would either build a slow-turn on circuit (series R, parallel relay, 15V trigger for coil) or place an appropriate surge-suppressing NTC varistor in line with it. They will absorb the surge with maybe 5 ohms, then cool back down and drop to near zero. Work great, cheap, easy. There’s an opposite approach possible with a PTC unit. I would insert a link, but every time i try to help out the mods here block my link thinking it must be a way to circumvent Audiogon making money on a sale :-(

realityu note: the 1/4F was a "hero experiment". Way past diminishing returns. But i’d go for 30-50,000 uF ( at as i recall 63V or higher). That ought ot make it sing. Bypass each (across the terminals) witha 100V dc film type which will have dialectic absorption ( the big sonic parameter) of roughly 50-100x better than a typical electrolytic.

Rodman - Your concern for the OP's gear is fine/ But please dont call my intentions into question. I was clear - I have the experience to tell him that the risks were small to nonexistent.  Why? its too long to get into but begin with the fuse and the effective series resistance of the transformer, combiend with the exponentially decreasing load of the charging capacitors.  with reasonable sizes, say 33k-50k uF, its simply not an issue. It simply can;t pass enough current to kill itself before the capacitor are charged. Even if it DID continue the fuse would blow.

Which brings me to the real reason for protection - which i suggested, although you conveniently ignored it.  Or maybe didn't understand it - i cant say.  The REAL reason, IMNSHO, is that once a bigger capacitor storage bank exists,a larger fuse is required, therefore less protection for myriad faults.

I believe the Hafler DH200 came with a 5A slow blow line fuse. My gonzo-filtered unit with a surge supression circuit, employed a 3A slow blow.  That means MORE protection.

I have built 100s of prototypes and experiments.  I have supervised the building of even more.  This is not idle speculation.

BTW through various ham fisted errors I have dead shorted the secondaries of transformers. I never saw one fail.  Eventually it will fail due to heat, but not nstantly, back to the fuse.

These are not mysterious error methods. The infinite current zero impedance transformer, sadly, does nto exist.  I'm still looking tho.

G