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Old 12th March 2012, 12:31 PM   #1001
pidigi is offline pidigi  Italy
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Hi!

Quote:
Originally Posted by tvrgeek View Post
TO get better sound, well a $150 e-bay Rotel suits us far better. Jump up a notch or two: Acrus, Forte, Aragon, Parasound, Adcom. A bit more, Nak, Krell, or whatever. Far cheaper. If you know which ones, Denon, Onk, Marantz all have made super units.
Well, I don't want to start the usual flame, but I have compared a Krell against a "modified" (by me) DH200: the owner of the Krell was a little bit disappointed
No need to report test results against $150 amps, but it is worth reporting a comparison with a 300B SE: the 300B amp sounded better. No discussion. But 8W aren't always enough, so the owner of the "modified" DH200 is looking for a 3 x 300B PSE (yep, very inefficient speakers..), meanwhile he keeps listening to the DH200. He is not going to search for a Krell, that's sure.

So, I agree with the "still is, bro!" version.

Ciao

Paolo
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Old 12th March 2012, 09:14 PM   #1002
tvrgeek is offline tvrgeek  United States
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One of the problems is that no amp is perfect. Each has certain faults. The Haflers fail my wife's ultra sensitive issue with loud horns and are marginal on my guitar string "metal-ness" test. So did a modified B&K 140 (smoother but still failing) , Parasound HCA 1200 (more detailed) and many others. Yet even my baby RA 840 Rotel passes both these tests. (The 951 is the same basic amp with modern mute and protection). Everyone has a different tolerance for one fault over another.

Obviously, I have not heard your mods. It would be interesting to compare to what I have done to my DH-120. Maybe you hit the magic parameters. I will gladly give them a try on my 220 if you would like to share them.

One thing for sure, it is easy to find things to improve in the Haflers without changing his basic topology. They were budget products. The 220 had Erno's full complementary input, but they did it with cheap parts, poor wiring and no protection system. 99.9% of the customers would not know the difference, so I would say it was well designed for it's target. If you follow his DIY progression ( 60, DC 100, Servo 100) in AA, you will see he made quite a few changes himself in understanding the outputs and in the way he addressed stability.

I have been trying to understand amp design and driving a lot of very skilled and esteemed designers crazy asking why the cheap Rotels sound so darn good. They are better than they should be. I was looking at a Niam schematic, it too is very simple in topology, but highly acclaimed. I have not had one to live with, so I do not know if it passes the horn test. I remember when I bought the B&K, the Aragon was the only amp I heard that I would say was better. I could not afford it at the time. The Acrus came out only a little later and I also remember being highly impressed. Having had neither at home, don't know if it can pass the test that so far, only 8x and 9x series Rotels pass.

A test against a $150 amp is worth reporting when it wins
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Old 12th March 2012, 09:15 PM   #1003
tvrgeek is offline tvrgeek  United States
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and read gootee's thread.
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Old 12th March 2012, 11:17 PM   #1004
gootee is offline gootee  United States
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Doh! Sometimes when you mention the Devil's name, it summons him. (So watch out for THAT...<grin>)

Actually, I am almost always forced to try to discount reports of listening tests, even when it's someone I know and trust. There are just WAY too many unknown variables.

Besides, my goal has always been the most accurate reproduction, even if it "sounds worse" to me. I'm not saying that I necessarily always know how to discern or even test which amp is more accurate. My point is simply that hearing "sounds better" in a report is an automatic red flag, for me, because it points straight into the morass of "personal preference", which is a term that I feel should be banned from all serious discussions of sound reproduction.

Edit: But my Adcom 585 sounds better than my Adcom 545 II, which sounds better than my Hafler DH-220, through either Magnepan MG-12 or Vandersteen 2Ce speakers, according to 100% of the people who have extensively evaluated all three of them with both types of speakers (both me and my son <grin>). None of them are tweaked at all but, to be fair, the Hafler has one channel for which I couldn't adjust-out the offset, completely, after receiving it (ebay, $130). So something is going on, there, that might need some attention before it can do its best.

Last edited by gootee; 12th March 2012 at 11:29 PM.
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Old 13th March 2012, 12:02 AM   #1005
fab is offline fab  Canada
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Default DH-120

Quote:
Originally Posted by tvrgeek View Post
...
Obviously, I have not heard your mods. It would be interesting to compare to what I have done to my DH-120. Maybe you hit the magic parameters. I will gladly give them a try on my 220 if you would like to share them.
...
Hi

I have not heard the DH-120 but its schematics shows a front end circuit that is not symmetrical at all and a cascode VAS thus the DH-200/220 topology is quite a different design so the sound might be quite different too...

Also, I am not sure if we can characterize an amp sound on one single test...
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Old 13th March 2012, 01:53 AM   #1006
tvrgeek is offline tvrgeek  United States
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Quote:
Originally Posted by fab View Post
Hi

I have not heard the DH-120 but its schematics shows a front end circuit that is not symmetrical at all and a cascode VAS thus the DH-200/220 topology is quite a different design so the sound might be quite different too...

Also, I am not sure if we can characterize an amp sound on one single test...
true and true. Also, I moved the DP from the VAS output where it loaded it asymmetrically to standard Miller comp, removed both comp caps in the IPS and the one on the cascode. Far more symmetrical. I also have Exicon outputs and the gate resistors are 680 & 470, moved to the sockets. The 2N5550's are now 5551's. Bias is lowered to 110mA.

I am not anywhere experienced to take sides on the symmetrical vs. not input. Many top designers say yes, some others say no. It is the result that matters. The well regarded mod cards for the 220 were not symmetrical, neither was the B&K.
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Old 13th March 2012, 02:12 AM   #1007
tvrgeek is offline tvrgeek  United States
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gootee
Ah yes, the 2Ce. The speaker that does nothing very wrong other than being ugly. It is one of only three my wife approved of the sound, but not the looks. Sequal and an Epos only when driven by Cary were the other too. Other than visuals, I don't understand why anybody buys any speaker other then the 2Ce up to about 2 grand. It is one of those products that is way better than it has any tight to be.

I was looking over the small Adcoms to play with next. 535 maybe. I remember "in the day" every store was pushing the 555 which I thought sounded harsh but had really good bottom end. I tend to like smaller amps, but that may be because I have only heard good smaller amps. Anyway, the 535 starts out with higher quality parts, mute and protection of a modern amp. Design by yet another luminary who haunts these pages, Mr. Pass. I don't think it has his patented bias spreader though. The 585 looks a bit big for my tastes, but then I run active crossovers for my woofers and don't have the need for low end power. I thought about applying what I have learned over in the lounge to an RB 951, but I hate to mess one up!

I was hoping Pablo would let us in on the mods he found so successful. I have a guinea pig in the shelf.
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Old 13th March 2012, 03:51 AM   #1008
gootee is offline gootee  United States
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I also have an Adcom GFA-535 Mk II, which supposedly has better parts than the non-II. I have read that the 535 is the best-sounding of the three (535, 545, 555), but haven't seen any comparison of the 535 and 535 II.

I like the 535II a whole lot, through my MG-12s (4 Ohms). I don't remember trying it with the 2Ces.

I do love the 2Ces, a whole lot. But I love the MG-12s quite a bit more than that. The only drawback I've found, with the MG-12s is that they are best used by only one person at a time, in only one location. I love that sweet spot but it is small.

The Adcom 585 was purchased because I wanted to see what the MG-12s could do, loudness-wise, before the bass started to audibly modulate the rest. With the 545 II I couldn't quite get there before the clipping/distortion indicators lit up, on the amp.

After I got the Adcom 585, I found out that the 2Ces have OVER-TEMP indicators, behind the socks, that flash red when they get too hot!

I later read about someone who I think had either the same amp (or was it the same speakers?) who turned it up "real loud" and left the room and when he returned one of the speakers was literally engulfed in flames, and the amp was still just playing merrily along. <grin>

Anyway, the 585 has significantly-better THD and IMD specs than the 535/545/555. And it sounds better (more accurate, more real; but not by a lot), to us, with both of those types of speakers. But having a lot of reserve power and therefore operating nearer to the bottom of its output power range might help it sound better, I would guess. Unfortunately, it cost more than three times what any of the others cost. And yes it is MUCH larger and much heavier than the 545II. The toroidal power transformer that's in it is the size of a small BIRTHDAY CAKE. On the bright side, it's rated to do 1000 Watts RMS per channel, continuously, into ONE (1) OHM loads (but the service manual didn't give any distortion specs for that).

Edit: Wait a minute! UGLY?! I LIKE the way the 2Ce looks!

Edit: I thought that NP also designed the 545 and 555. No?

Last edited by gootee; 13th March 2012 at 03:56 AM.
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Old 13th March 2012, 08:23 PM   #1009
tvrgeek is offline tvrgeek  United States
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My wife said something like not having those ugly toumbstones in her living room.
She puts up with this, but I had to promise to hide the woofers.
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Old 13th March 2012, 08:30 PM   #1010
tvrgeek is offline tvrgeek  United States
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I think he did the entire line. The larger have his spreader circuit from the schematics I saw. I find looking at cost constrained main-line examples to be interesting as you can see where their real priorities are vs. icing on the cake. 1K into One? No wonder the sub guys love them. Not scrimping on outputs I suspect is one of those priorities I mentioned.

Off to look for a Mk II.
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