Hi!
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
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
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
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
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.
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.
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DH-120
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...
...
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...
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.
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.
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.
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?
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?
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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.
Off to look for a Mk II.
No Mk II's out there right now. Missed last week I guess.
Pablo, what about your mods on the 200? There is not a lot to work with keeping the same topology. Lower noise parts, a bit of moving grounds off the board and back to the star point, a bit of PS work. Cascode the IPS maybe? Switch to JFETS on the input?
Pablo, what about your mods on the 200? There is not a lot to work with keeping the same topology. Lower noise parts, a bit of moving grounds off the board and back to the star point, a bit of PS work. Cascode the IPS maybe? Switch to JFETS on the input?
Checked schematics, 535 Mk II has third output. Went back to standard bias spreader. No protection and no relays. The RB 951 has an advantage there. Mk I was DC coupled, Mk II, AC coupled, DC servo. Mk II is odd in that it takes the input off the inner of the LTP. Different amps that's for sure.
here I am!
sorry guys for the delay, I happen to work (way too much, lately) so the time left for the rest is really scarce...
You guessed almost all the mods "tvrgeek" (I suppose this is not your real name, but that's ok, neither Pablo is mine). The circuit remained the same. The pcbs are new, I used (matched) 2SK1058/2SJ162 as output devices, matched bjt also in the rest of the circuit (2N5551 here too), mf resistors, wima caps. The ground connections are completely different of course. Bigger trafo, sprague electrolytics, etc, etc... Basically all "standard" mods, after all. No magic here... Ah, forgot to say that the chassis is not the original one.
Yes, it is very difficult to "trust" the results of listening tests, even more if they are reported by someone else. That's way I was really surprised by your firm statements about the superiority of 150$ amps respect to Haflers. I'm not going to argue about the gift of your wife, but I cannot consider this gift as my way to judge power amps
So, as usual, that's my experience. And of course YMMV.
Ciao
Paolo (not Pablo)
sorry guys for the delay, I happen to work (way too much, lately) so the time left for the rest is really scarce...
You guessed almost all the mods "tvrgeek" (I suppose this is not your real name, but that's ok, neither Pablo is mine
). The circuit remained the same. The pcbs are new, I used (matched) 2SK1058/2SJ162 as output devices, matched bjt also in the rest of the circuit (2N5551 here too), mf resistors, wima caps. The ground connections are completely different of course. Bigger trafo, sprague electrolytics, etc, etc... Basically all "standard" mods, after all. No magic here... Ah, forgot to say that the chassis is not the original one.Yes, it is very difficult to "trust" the results of listening tests, even more if they are reported by someone else. That's way I was really surprised by your firm statements about the superiority of 150$ amps respect to Haflers. I'm not going to argue about the gift of your wife, but I cannot consider this gift as my way to judge power amps
So, as usual, that's my experience. And of course YMMV.
Ciao
Paolo (not Pablo
)
Apologies for miss spelling. Don't know used prices on the Continent, but I don't think I went over $150 for any of my Hafler's either.
Careful matching is a really big plus combined with 1% resistors. I bet the second harmonics dropped a bunch as it does not look like they matched the inputs originally, or at least not as close as you can get out of a batch of 20. Actually 40 for the 5551's and 5401's. The first batches were On-Semi, and I would consider them only semi-usable. Gain was "maybe". Fairchilds for the second batch. I think you have shown execution is as important as topology.
The Rotels of the vintage I speak are also simple on paper, but they just work better. I don't know why, which is what got me started in amps. There must be a reason. They don't use exotic parts either. Naim, MusicFidelity, and Creek are all highly respected and have very simple topology.
I have been scoping out newer transistors. 2SC970 and the like. Far lower noise, more linear. I am not going to spring for a new transformer, as lets face it, the transformer and heat sinks are half the cost. I would be more inclined to derate a 220 into a 75W by regulating the IPS and VAS rails at a lower level.
You are still left with no remote power control, no mute, or output protection system that one finds in newer amps.
It would be fun to know which gives more payoff, twin rectifiers and caps, or single rectifier and pi filter the same 4 caps. Did you do everything at once? I wonder, was the power supply and grounding what made the difference, or the exotic caps? Newer outputs?
Careful matching is a really big plus combined with 1% resistors. I bet the second harmonics dropped a bunch as it does not look like they matched the inputs originally, or at least not as close as you can get out of a batch of 20. Actually 40 for the 5551's and 5401's. The first batches were On-Semi, and I would consider them only semi-usable. Gain was "maybe". Fairchilds for the second batch. I think you have shown execution is as important as topology.
The Rotels of the vintage I speak are also simple on paper, but they just work better. I don't know why, which is what got me started in amps. There must be a reason. They don't use exotic parts either. Naim, MusicFidelity, and Creek are all highly respected and have very simple topology.
I have been scoping out newer transistors. 2SC970 and the like. Far lower noise, more linear. I am not going to spring for a new transformer, as lets face it, the transformer and heat sinks are half the cost. I would be more inclined to derate a 220 into a 75W by regulating the IPS and VAS rails at a lower level.
You are still left with no remote power control, no mute, or output protection system that one finds in newer amps.
It would be fun to know which gives more payoff, twin rectifiers and caps, or single rectifier and pi filter the same 4 caps. Did you do everything at once? I wonder, was the power supply and grounding what made the difference, or the exotic caps? Newer outputs?
Yup. 1KW into 1 Ohm, continuously, for each of two channels. It's right on the specifications page in the official service manual.
The seller's last line in the ebay listing was "She'll bring the thunder!".
I haven't tried one-Ohm loads, yet, though. My MG-12s are rated at 4 Ohms and the 585 is rated for 400 Watts into 4 Ohms. But I'm sure that I use only a small fraction of that.
I'm thinking that it might be very interesting to try paralleling four identical pairs of Magnepan 4-Ohm speakers. They seem to be at their clearest at lower volume levels, which is not extremely low (more like the "natural-sounding" level) but the MG-12s at least are not quite as good-sounding, I think, when they are pushed to extremely-high SPLs. So maybe with more than one pair, I could get much higher SPLs but with the total clarity of the lower volume level for each one.
Or imagine paralleling eight pairs of 2Ces, with one amp! <grin>
I wonder if those two scenarios would just be a mess, or if there would be a way to get a good soundstage image, if they were all in one room and devoted to one stereo listening position. I could see experimenting with stacking the MG-12s vertically in pairs, too!
Maybe then I'd want another 585 or two, so I could biamp or triamp! <grin>
Actually, I did purchase two of the 545 II amps, and the 535 II and the DH-220, thinking I might biamp or triamp some things. I even have schematics and everything I need (probably x100-to-1000) to build an analog active line-level crossover that would duplicate the (two-way) MG-12s' original crossover characteristics. I guess I need to spend less time at the computer and throw those things together and try it!
But for now, back to some Steely Dan!
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hey, c'mon, no need to apologize!
Quite often I find myself doing a "cut and paste" when replying to an email in order to not spell wrongly the names
Actually the number of Haflers you can find used around here is not high. That's why I decided to go for a clone instead of modifying one
I agree with you. The first clone I have built wasn't using matched 5551/5401 nor 2SK1058/2SJ162. The result was not so impressive. The rest of the amp (grounding, caps, etc) remained the same in the second clone, but using matched devices really gave a big step forward
And this is really fascinating, quite often a simple topology gives best results. Simple, but not naive, and I think that this is the secret!
Nice idea the 2SC970, did you manage to try them?
I was also thinking about a low power version, mainly to test the difference in using a pair (or three as I do in the latest clones) output devices
yeh, protection IS the main weak point of this amp. But it is quite easy to install a simple circuit to perform mute/output dc protection without spending too much/degrading the sound (not like the original fuse....).
In my experience a preamplfier is needed in order to get the best from them. So remote control is done in the preamplifier.
I can't say exactly, but my feeling is that grounding/layout are quite important. "Exotic" caps (well, wimas are not really exotic), 1% resistors, output devices are "second order" improvements. As I said, a big step forward is given from matched bjts.
There are still some other improvements that I would like to test (different bridge rectifier, changing VAS transistors, regulating the voltage of the board, etc). And then, the next step is trying to change something in the topology.
The "perfect" amplifier doesn't exist. When you reach a good quality, then quite often it becames a matter of individual taste. A friend of mine cannot live without extreme micro details but he doesn't care too much for a correct soundstage, for example.
For this reason there are on the market hundreds of different power amps..
Ciao!
Paolo
I have not tried the new parts. I am working my way through analysis trying to actually understand what I am doing and why. Q7, 9, 10 and 11 in the 120 need more average power than the 907/1085 should provide so I am looking at other parts. KSA916/KSC12316 or 2SA695/2SC2235 maybe. I am waiting on more books to learn a bit more about the transistor parameters so I can pick them with more than just SOA and NF. I want to pick current production parts.
In my study, it turns out good protection circuits are really hard. Big second on the preamp as you must have a low Z source for lowest noise through the IPS. By remote, I meant remote power on and off.
In my study, it turns out good protection circuits are really hard. Big second on the preamp as you must have a low Z source for lowest noise through the IPS. By remote, I meant remote power on and off.
gootee,
Don't Maggies get really ugly when over driven and have a habit of going "
poof"? Maybe two pair of Peerless XLS's as woofers. They are good clear up to 200 Hz or so which would be a big help to the MG-12's. ( old paper ones, no idea about the new metal cones. I don't like metal cones). I am sure the guys in the sub threads could come up with ideas to tax the Adcom while getting every cop in town knocking on the door which you won't be able to hear anyway.
Don't Maggies get really ugly when over driven and have a habit of going "
poof"? Maybe two pair of Peerless XLS's as woofers. They are good clear up to 200 Hz or so which would be a big help to the MG-12's. ( old paper ones, no idea about the new metal cones. I don't like metal cones). I am sure the guys in the sub threads could come up with ideas to tax the Adcom while getting every cop in town knocking on the door which you won't be able to hear anyway.