@itsjust me-
I’m certain everyone is duly impressed, with your expertise.
Just keep in mind: you don’t stand alone, with however many decades of experience you’ve under your belt.
As I mentioned: aside from the very possible failure issues, which could easily be created by someone without the experience to prevent them, there are the EMI/noise effects that can be created.
I’ve had to undo some bonafide abortions, in the past 40 years, created by those that didn’t know what they were doing.
The OP’s only interest was that of a power cord replacement.
And, directly to the point of my previous post: You failed mention anything about, "reasonable sizes", when you said, "THE BIGGEST CAPACITANCE POSSIBLE".
There’s enough room in the typical Hafler chassis, to install much more capacitance than advisable.
Happy listening!
" ...with reasonable sizes, say 33k-50k uF, its simply not an issue."
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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
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Thanks to everyone for your input. It spoke to John Hillig at Musical Concepts and he is really the Hafler upgrade guy. Lots of experience. I think I will have them upgraded by John for a second system. Thanks to BPoletti for the contact.
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@itsjustme -
In my book: informing another on ways to prevent catastrophic failures (ie: upgrading rectifiers, etc), BEFORE they cause them (ie: by installing biggest capacitance possible), is simply sagacious, but- that’s just me.
A transformer failure is a real possibility and much more expensive than $3.00.
But then: why should YOU have, "worries", about THEIR results, right?
ie:
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.
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Have fun. Cord will certainly cost more and do less.
Some think zero, others disagree.
Certainly the other mods you suggest would make real differences.
Including the outlet.
Compared to the cord, they are useful things.
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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.
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Be careful with your acceptance of advice!
When choosing the values of a power supply's filter caps, it's important to understand how the supply/circuitry functions.
ie: When a DH-120 is switched on: the capacitors initially present (what appears to be) a dead short to the amp's 8A (OEM) rectifier bridge. The greater the filter capacitance: the higher the current necessary to charge the caps.
Increasing the capacitance beyond a certain point, in most amps; it's easy to end up with blown rectifiers (possibly: a burnt transformer).
Of course: much of the above depends on how well the amp is protected, but: too much capacitance is simply asking for trouble.
It's always been my practice, when addressing power amp improvements (50+ years now), to first upgrade the rectifiers/rectifier tube/bridge, as that's always made the most marked/audible uptick in presentation. WHY? Because, in most cases: manufacturers don't use the best/most expensive parts they can find.
An increase in filter capacitance can reduce ripple in a power supply, but: going too far can change (decrease) conduction angles, increase peak currents and result in EMI/noise generation, in/from SS rectifiers. The harmonics of that EMI/noise can easily defeat any performance gains, gleaned from ripple reduction.
https://electronics.stackexchange.com/questions/217212/how-can-i-observe-rectifier-switching-noise
'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). "
+1 for the rest of that post, of course.
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Agree with the above comments, especially in terms of the priority/order in which things ought to be done. Go ahead and replace that old power cord--but do the other stuff first. Could be a very satisfying project!
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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.....
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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
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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.
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The Hafler DH 120, owned by the OP, has a " captive " cord, not an IEC connection.
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I started another thread that presented the perspective of one electrical engineer that works in the audio industry doing analog circuit design here. That might be interesting reading on why power cords MIGHT make a audible difference in how your amplifier sounds.
Practically speaking, a no cost way to try this out if you are an Amazon Prime member might be to buy several power cords via Amazon. Plug them into your Hafler amp and see if you hear a difference. If you hear a difference, you've answered your question. Hear no difference? Power cords go straight back to Amazon. In my experience, any difference you might hear should be immediately evident OR perhaps power cords make no difference (or at least no difference on your amp).
I personally think a Shunyata Research Venom V14 power cord at about $150 is a great starting point based on listening to a number of power cords loaned to me by a friend, but I don't see that Amazon sells Shunyata products. Amazon does have Audioquest power cables & Pangea power cords available through Prime. For an amp, perhaps ideally find a power cord with greater current carrying capacity.
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I have changed out hundreds of captive ac cords since before the net, and obtained my parts from either HD or Lowes. Now I order everything from the web. As far as a difference ? Absolutely ! Every possible " sound quality " description we all use in this hobby, based on our ears, is enhanced / enlarged. This, just by a heavier gauge wire and superior connector / plug. Your Hafler is a nice amplifier, and would easily exhibit improvements from the design, benefiting your ears. Enjoy ! MrD.
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BTW, one of my band mates brought his ancient Hafler amp to see how it sounded in my system. I was shocked that it more than held its own against my McCormack DNA 0.5 Rev. A. Not sure which model his Hafler was though, but I was really impressed and could’ve easily lived with that amp, so rehabbing it might not be a bad idea and a good investment. FWIW.
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Thanks for all of your input. Much appreciated!
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@wlp3
Sorry you were surprised with some of the responses. I think most of it is due to extra tight underwear. Or, possibly a lack of naps.
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Replace the power supply caps and any electrolytic bypass caps on the individual amp channels. You'll get much better return on investment.
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Contact John Hillig at Musical Concepts to determine REAL options for spending your money for amp improvements.
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@wlp3 I might suggest you get a really good drill bit and power through the steel and find a grommet that will capture the cable of your choice. Forget an IEC--worthless additional connection in this case and would be a pain in the rear cutting through all that steel. Go with the cable you desire and size accordingly.
I might suggest Supra Lorad would be a good choice. Go for the heavier gauged one. Flexible, easy to work with.
Also, agree with replacing those caps
Lots has changed over the past 30 years, especially civility. Very sad but there are still those out their willing to give a hand. Good luck.
PS-built a Hafler pre/power amp years ago. Good memories.
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Hafler rock solid and worth investment imo having built many back in the day. I would go the IEC route if you plan on refreshing / modifications.
Best to you, glad you are back into audio after a hiatus…..
Jim
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Not sure I’d spend too much a 25 year old amp, but a better PC can definitely make a difference. I’d recommend trying Cullen Cable as they’re a solid upgrade over stock cables but don’t break the bank, and they offer a good trial period so if it doesn’t make a significant difference you can just send it back. They just got bought by Wyred4Sound so I’d think you’d need to go to their site to order but not sure. Definitely worth a try though. Best of luck.
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it can be a fun project..I'm having a Classe' Five refurbished, similar vintage to yours...Classe' actually back then, recommended an upgrade power cord on many of their amps and preamps...
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Thanks to all for your responses. I appreciate your input.
The belligerence from some in response to someone innocently asking questions after having just gotten back into the hobby after 30 odd years is interesting and unfortunate.
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@wlp3-
No one can tell you whether YOUR system/ears will (or can) resolve/discern any improvement(s), if your Hafler's PC is upgraded.
Having done a number of such upgrades, on Hafler equipment: I will state that the move invariably brought a smile their owners' faces.
I would, however, recommend replacing any and all electrolytic capacitors, of your DH120's power supply and driver boards, before bothering with the PC. Yours are around 30 years old.
It's been my experience: the better the condition of any unit's stock circuitry, the better (more audible) the result of any upgrades/tweaks.
Happy listening!
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I find it funny in that in one post the OP is trying to get the best out of his fiber optic internet.....and now he posts about adding a power cord to a amp that is over 30 yrs old.
you could get the amp modded, but the mod alone costs more than the amp is worth.
Hafler Amp (musicaldesign.com)
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The local Master Of The Deluded ("Trust ME, I’m a fictitious operative!"), recommends joining a delusional, "Society".
Reverse psychopathy?
Projection?
Either or both =
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@carlsbad : those old Hafler SS amps/preamps were made before IEC outlets were in common use. I have a Hafler 220/110 pair - both with captive AC cords.
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If you want to experiment buy an IEC outlet. Cut off most of the old power cord, leaving several inches. Strip the two conductor ends. Attach each copper conductor to a screw terminal on the back of the IEC outlet. Now you can use any power cord with a male IEC connector.
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Does it have an IEC connector? If so, it is Easy to start with a generic one off ebay for less than $50 and see if you hear a difference. read the fine print to make sure it is 10ga. I like the woven GR research cable. I think just about all amps benefit from a larger power cable unless the power supply is choked by a long 14 ga wire in the wall or a power conditioner.
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Power cables do make a difference, If you haven't heard it you either aren't listening or didn't try the right one. You will have to solder the connection to the amp board and a large diameter power cable will require you to probably drill out the case and find the right grommet. The GR is good because you can specify only one end but getting the other to match up is going to take some work.
For my Dynaco amp I used an inexpensive heavier gauge power cord because getting really large wires or cutting the case to put a plug adapter was more than I was prepared to do.
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The sound of an electronic component starts with its power supply. NOT with the wire connecting it to the AC outlet. If you believe otherwise then I recommend joining the Flat Earth Society.
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