The 565 will drive a 1 ohm load , i think it has a 1.7k transformer and 10pr outputs / monobloc, I just did not like the sonics vs my other amps, it is a power house thou ....
I think i said 585 before, my error it was the 565 mono units i jad meant to say , no the 585 wont go there ....
I think i said 585 before, my error it was the 565 mono units i jad meant to say , no the 585 wont go there ....
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Yes, I'm sure it will handle low impedance loads, but for me a true measure is whether it can be done continuously, until the output devices start to overheat and the protection cuts in. Even the 4ohm continuous rating only holds if an optional fan assembly is fitted, which I suspect the majority won't have.
The good thing about the Adcom is that it has decent voltage drive, 80V rails which helps to give it good headroom on transients. I still have a Perreaux 2150B, with 90V rails, but originally with relatively weak smoothing caps; the lack in the latter makes all the difference ... the first heavy duty tweaking I did, years and years ago, was to rip this out, and add a vast array of small, paralleled caps, I think about 4 x the original capacity ...
Frank
The good thing about the Adcom is that it has decent voltage drive, 80V rails which helps to give it good headroom on transients. I still have a Perreaux 2150B, with 90V rails, but originally with relatively weak smoothing caps; the lack in the latter makes all the difference ... the first heavy duty tweaking I did, years and years ago, was to rip this out, and add a vast array of small, paralleled caps, I think about 4 x the original capacity ...
Frank
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The 565 will drive a 1 ohm load , i think it has a 1.7k transformer and 10pr outputs / monobloc, I just did not like the sonics vs my other amps, it is a power house thou ....
I think i said 585 before, my error it was the 565 mono units i jad meant to say , no the 585 wont go there ....
The 585 is essentially two 565s in one case, but with only one (really-huge) transformer.
I can't identify any "sonics" when listening to it. It seems extremely neutral and transparent. But maybe I'm too old and my high-frequency hearing ability is too far gone. It sounds literally identical to the Luxman 1050 and HK 560 that I mentioned, when all else is equal; just extremely clear and clean, with perfect imaging. None of them contribute anything of their own, to the sound, as far as I can tell.
There is at least one known problem with the 585 and 565: A bad batch of some well-known high-end 220 uF caps was used on the servo boards, which began to leak. If that happened, you might have been starting to get DC on the outputs, which might have biased your speaker motors off-center, changing the sound.
Walt Jung was on the design team for those amps and has posted here on diyaudio about the servo board cap problem.
@Tom, @Frank
I've mentioned this before, but just in case you didn't catch it ...
One of the oldest trick in the book, and one of the first I came across, was introduced by the Japanese tweakers. They called it a composite cap.
The reasoning is that each and every material used for capacitors has its own properties, weaknesses and strong points, and essentially that none is perfect. To get nearer to perfection, one should combine three materials, for example, polyester, polyprolyene and polycarbonate. Say you need a 3 uF cap somewhere - put one of each in parallel for the best audible result. If they cannot be of equal value, then make sure that the fastest among them (polycarbonate) has the largest value.
In my day, I experimented quite a bit with this and I think they are definitely on to something. No single value I ever used could match a composite one, even if by a small bit.
My general feeling is that the best decoupling capacitor is the one not there, i.e. I am pro DC servo arrangements, I am not against cap coipling, but if I'm going to do it, it will definitely be a composite cap. It's not like you need tons of them.
@Frank
What you propose for critical listening is what I have been doing for decades now. Honestly, I haven't come up with a better method yet.
Regarding chip power amps, a friend of mine is kinda nuts about them and has been fooling around with them for quite some time. I have heard some of his work, and truth be told, some of the results he obtained are impossible to ignore, simply because they sounded really very, very good.
His best work was an amp with a Nat Semi chip power amp, I think around 50 WRMS/8 Ohms, which was preceeded by a FET input op amp as a buffer, and he was generous with both the main electrolytics and on board local power supply decoupling. Now, that one made many other much more expensive amps sweat tryuing to cach up at room volume, and I should mention his speakers do someting like 91 dB/2,83V/1m, meaning reasonably efficient.
Another friend bought via the Internet one of those DIY boards which use Nat Semi's all-but-the-output-stage driver chips. The actual output used four pairs of 2SC5200/2SA1943 trannies, and with 22,000 uF/63V caps per power line (88,000 uF total), he did obtain some rather good results.
The point is, there are a lot of worthwhile options floating around.
I've mentioned this before, but just in case you didn't catch it ...
One of the oldest trick in the book, and one of the first I came across, was introduced by the Japanese tweakers. They called it a composite cap.
The reasoning is that each and every material used for capacitors has its own properties, weaknesses and strong points, and essentially that none is perfect. To get nearer to perfection, one should combine three materials, for example, polyester, polyprolyene and polycarbonate. Say you need a 3 uF cap somewhere - put one of each in parallel for the best audible result. If they cannot be of equal value, then make sure that the fastest among them (polycarbonate) has the largest value.
In my day, I experimented quite a bit with this and I think they are definitely on to something. No single value I ever used could match a composite one, even if by a small bit.
My general feeling is that the best decoupling capacitor is the one not there, i.e. I am pro DC servo arrangements, I am not against cap coipling, but if I'm going to do it, it will definitely be a composite cap. It's not like you need tons of them.
@Frank
What you propose for critical listening is what I have been doing for decades now. Honestly, I haven't come up with a better method yet.
Regarding chip power amps, a friend of mine is kinda nuts about them and has been fooling around with them for quite some time. I have heard some of his work, and truth be told, some of the results he obtained are impossible to ignore, simply because they sounded really very, very good.
His best work was an amp with a Nat Semi chip power amp, I think around 50 WRMS/8 Ohms, which was preceeded by a FET input op amp as a buffer, and he was generous with both the main electrolytics and on board local power supply decoupling. Now, that one made many other much more expensive amps sweat tryuing to cach up at room volume, and I should mention his speakers do someting like 91 dB/2,83V/1m, meaning reasonably efficient.
Another friend bought via the Internet one of those DIY boards which use Nat Semi's all-but-the-output-stage driver chips. The actual output used four pairs of 2SC5200/2SA1943 trannies, and with 22,000 uF/63V caps per power line (88,000 uF total), he did obtain some rather good results.
The point is, there are a lot of worthwhile options floating around.
Good to hear ...
50W amp, 91dB sensitivity is all you need to get impressive sound levels. Currently, the setup here uses 15W chip amps into speakers of that sensitivity, and that creates deafening levels, ringing in the ears with a modern, restricted dynamics recording.
I just mentioned on Curl's Blowtorch thread that a Marshall 350W guitar amp uses just 4 chip amps to do the job well enough for muso's ...
Yes, that's the key, there are myriads of ways to get there. Only, from my POV, too many people sabotage their chances of getting impressive sound because of silly shortcomings, little weaknesses that undermine the real potential ..
BTW, that email address you posted didn't work for me, bounced ...
Frank
Good to hear ...
50W amp, 91dB sensitivity is all you need to get impressive sound levels. Currently, the setup here uses 15W chip amps into speakers of that sensitivity, and that creates deafening levels, ringing in the ears with a modern, restricted dynamics recording.
I just mentioned on Curl's Blowtorch thread that a Marshall 350W guitar amp uses just 4 chip amps to do the job well enough for muso's ...
Yes, that's the key, there are myriads of ways to get there. Only, from my POV, too many people sabotage their chances of getting impressive sound because of silly shortcomings, little weaknesses that undermine the real potential ..
BTW, that email address you posted didn't work for me, bounced ...
Frank
Frank, I have two functional e-mail addresses, and they are:
dvv@beograd.com
dvv@bitsyu.net
Both worked this morning just fine.
Regarding amps, I agree, too many people are locked into their point of view beyond redemption.
Not too long ago, if you didn't have a FET input, some would swear it wouldn't even work. Next, there was a FET input with a casocde - again, some people think that's the ONLY way.
I am not trying to dispute the merits of such topologies, but just to spite such people, my HK 6550 uses a simple as can be differential input, and I'll wager it will outshine many with complex circuitry at the input.
So, I need not go outside my own house to verify that any topology, when applied knowingly, will produce good results, more often than not better than many a device slapped together according to current fashon.
Zigactly! (Drunken Obelix to Asterix in "Ceasar's Laurel Wreath").
If for some reason not possible to obtain with equal values, it was suggested that the largest value used should be polycarbonate. It seems nothing else on this planet can match its extraordinary speed.
Well aware and all my adcoms are in tip top shape , no issues anywhere (565,555) fresh caps etc ..
I'm currently redoing the 200cx, Imo the best value in power amps if spending below 1k, you usually can find them in the 500-700 region ..
http://www.stereophile.com/solidpoweramps/741/index.html
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Zigactly, too ...
I always get a bit twitchy when people use the word "speed" with audio stuff ... to me, they really mean low distortion when they say this. Good sound has tremendous drive, PrAT is another term for this, and it only really falls into place when the level of audible distortion is sufficiently low.
To me, people are confused about distortion: there's obvious distortion - a cheap radio overloading; compression, when an amp sounds like it's got no more to give; edgy, hifi style sound; or flat, grey, poorly detailed sound. These are all forms of distortion, all are not true to the source, what the recording has encoded in it. So a system that lacks "speed" is a distorting system, it's not reproducing what's on the recording correctly ...
Frank
Vac, don't take it at face value, that was just an example. I suppose half the fun of tweaking is in finding the just right combination for you.
And the Good Lord knows you have your choice of materials.
Oh, BTW, I never said polystyrene - I said poyester, polyproypelene and polycarbonate.
Personally, when I need small values in the pF range, whenever possiblem, I go for silver mica, or, better yet but often hard to find, multilayer ceramic caps by Siemens. Damn expensive, but second to none.
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Zigactly, too ...
I always get a bit twitchy when people use the word "speed" with audio stuff ... to me, they really mean low distortion when they say this. Good sound has tremendous drive, PrAT is another term for this, and it only really falls into place when the level of audible distortion is sufficiently low.
To me, people are confused about distortion: there's obvious distortion - a cheap radio overloading; compression, when an amp sounds like it's got no more to give; edgy, hifi style sound; or flat, grey, poorly detailed sound. These are all forms of distortion, all are not true to the source, what the recording has encoded in it. So a system that lacks "speed" is a distorting system, it's not reproducing what's on the recording correctly ...
Frank
I know what you mean, Frank, but there is some merit in talking about speed.
Here's an example - what use your amp's capability to slew at say 40 V/uS, and much more important, say 10 A/uS, if your filter caps will knock this down to say half the nominal value?
This may well be more of a technical point of view, because even if they do limit the amp's speed, the final speed may well be at or above what we actually need in real life, but I for one would be seriously stressed if I busted my behind ro make an amp fast only to have the caps cut it down.
I have said this before, and I'll say it again - the ONE AND ONLY capacitor spec sheet which even mentioned this speed was that of Siemens Sikorel professional series, they clearly stated that it did 100 V/uS and 8A/uS. You don't really want to know their price. It's all EPCOS these days, as Siemens and Matsushita established EPCOS as a joint capital manufacturing company some years ago.
And while speed is not everything, and maths may show we only need like 5 V/uS, I agree with John on this point 100%, we should, just in case, aim for something like say 40 V/uS. This necessarily forces us to consider the caps in that light as well.
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And, perfect timing. Courtesy of another audio forum I've found a YouTube clip, recently posted, which has captured extremely well the key failing of current setups. This clip is intended to demonstrate how impressive the "best" high end can be but mainly serves to do other ...
The clip is Hi-End System vs percussion band - YouTube. The latter plays first, is recorded and then you hear immediate playback. First problem is that the system playback is too soft in comparison, so you need to turn the volume up, to match levels. Which more acutely reveals that key problem I referred to ... and that is, poor rendition of the treble. The recording as compared to the live version badly lacks a sense of realistic dynamics, essentially because the treble content is not "right" - I have no trouble picking this on my ordinary PC monitors, which have very average treble by most standards. This is something that I've always focused on, to me this is absolutely key to getting audio to be "correct"!
I've captured the HD version of the clip, which has excellent sound by YouTube standards; and intend to do some comparative analysis of the two sections of the audio track, see what I come up with ...
Frank
The clip is Hi-End System vs percussion band - YouTube. The latter plays first, is recorded and then you hear immediate playback. First problem is that the system playback is too soft in comparison, so you need to turn the volume up, to match levels. Which more acutely reveals that key problem I referred to ... and that is, poor rendition of the treble. The recording as compared to the live version badly lacks a sense of realistic dynamics, essentially because the treble content is not "right" - I have no trouble picking this on my ordinary PC monitors, which have very average treble by most standards. This is something that I've always focused on, to me this is absolutely key to getting audio to be "correct"!
I've captured the HD version of the clip, which has excellent sound by YouTube standards; and intend to do some comparative analysis of the two sections of the audio track, see what I come up with ...
Frank
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The difference is obvious, I'd say.
The reproduced version has lost a lot of sheen and bite and overall sounds diluted.
I checked and rechecked the above comment by several runs over my speakers (Luxman C-03 preamp > Marantz 170 DC power amp > speakers) and headphones (HP PC > Luxman C-03 preamp > Sennheiser HD 598 cans).
The reproduced version has lost a lot of sheen and bite and overall sounds diluted.
I checked and rechecked the above comment by several runs over my speakers (Luxman C-03 preamp > Marantz 170 DC power amp > speakers) and headphones (HP PC > Luxman C-03 preamp > Sennheiser HD 598 cans).
Of course. But, to me, to my ears, this encapsulates perfectly where normal audio gets it wrong; I listen to an expensive system, in the flesh, and they sound just like that system does via the clip, or worse. They should sound like the live version that comes up first; you have no problem picking up the much higher quality, realism of the musicians performing -- and this is a YouTube clip, for heavens sake! Supposedly a cheap and nasty way of putting up snippets of sound, but it still gets the message through!
So what's the problem? Well, we're hearing a recording of system playback at close to live levels, and it's not working in spite of all the expensive machinery thrown at the "problem". It's not the recording that is being played by that system that's at fault, because we can hear what's on that through a set of headphones, PC monitors, being the first half of the clip! That leaves the playback mechanism as the guilty party, but why is that so ...?
This is precisely the problem that I've been working on for the last couple of decades, and it's not an easy one to knock over. You mention "loss of sheen and bite", and that to me is another way of saying distortion of the high frequency component of the playback. Some may say that this is a generic problem of speakers at decent volumes, and I say this is wrong. Over and over again I've dealt with systems sounding like the second half of the clip, the speaker version, which I then tweak to perform, sound like the "live" section, the first half. The speakers stay the same, the amp, the source, etc, are all retained; but all the issues that drag down the quality, create a "diluted" playback, are sorted out ...
Frank
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dvv, I am surprised ... projects for electronic volume control are extremely thin on the ground; these were what I found on a first scan: MiniVol PGA2320 Volume Control - error404's Audio DIY Endeavours and a thread mentioning others, http://www.diyaudio.com/forums/analog-line-level/212749-looking-pga2320-pcb.html. All use processors to do the fiddly stuff, but the first one, MiniVol, seems to be well done - the processor is put to sleep when not needed - , people have had success with it.
Personally, I have no hangups about digital volume controls, they give me the sound that I'm after. In that live vs. playback clip, the "diluted" quality is exactly what I find mechanical, analogue, gives; hence I steer well away from it ...
Frank
Personally, I have no hangups about digital volume controls, they give me the sound that I'm after. In that live vs. playback clip, the "diluted" quality is exactly what I find mechanical, analogue, gives; hence I steer well away from it ...
Frank
Fig. 1 here shows the problem:
http://www.jensen-transformers.com/an/an004.pdf
Maybe you could ask John, but it appears to be the AC power line current from the capacitance of the transformer windings and core that goes to the chassis ground and then (in a modern 3-wire power connection) to the ground pin at the power plug. Also, some power entry modules have capacitors between hot and ground and between neutral and ground (especially when connected to a switching power supply), and a small amount of power line current flows through these capacitors as well. Since wire (specifically the ground wire in the power cable) has greater than zero resistance, this causes a small AC voltage on the chassis relative to the ground in the power plug, and also relative to the "ground" on the chassis of some other equipment, even when plugged into the same outlet. This usually makes it into the signal path as shown in the above file.
Balanced connections are in general less affected by such ground currents, as well as being more immune to other kinds of interference. I recall an article in Audio Amater a few decades (!) ago titled something like "Is it time for balanced interconnects in consumer audio equipment?" I thought back then it would be expensive, but considering all the "high end" crap with unbalanced gold plated RCA connectors and expensive boutique interconnects, balanced connections would solve a lot of problems at minimal expense.
Here's a lot more - he's selling his own brand of transformers and balanced input buffers as solutions, but he describes the problems very well:
http://www.jensen-transformers.com/an/generic seminar.pdf
http://www.aes.org/sections/pnw/pnwrecaps/2005/whitlock/whitlock_pnw05.pdf
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