It would be something of a happy accident if it sounded great seeing as its been optimized for lowest possible THD (and two tone IMD). At least that's my understanding of the design - kinda like a Halcro, but with classD.
Have already mentioned a key one, that I took to that show, several times: Peter Green Splinter Group (album) - Wikipedia, the free encyclopedia - very well recorded, live sound; great instrumental bite, excellent air ...
Good example of a 'good' recording ... and then a 'poor' one, to ruthlessly expose every system shortcoming: Dionne Warwick, Walk on By - Axis CDAX701398, a cheapie compilation.
For testing 'big' sound, can't go past Led Zep I, original CD release - most systems make a complete mess of this, because they can't resolve the extreme reverb effects that were used ...
Good example of a 'good' recording ... and then a 'poor' one, to ruthlessly expose every system shortcoming: Dionne Warwick, Walk on By - Axis CDAX701398, a cheapie compilation.
For testing 'big' sound, can't go past Led Zep I, original CD release - most systems make a complete mess of this, because they can't resolve the extreme reverb effects that were used ...
The only time I heard a Halcro was in show demo mode - did brillantly with vinyl, but was very mediocre with CD; how much did system interactions play a part - who knows ... ?
No ... just the first Splinter album - I can't see anyone complaining about the sound on this.
If you want fantastic house rockin' music, just spin Hound Dog Taylor: A Tribute - Various Artists | Songs, Reviews, Credits, Awards | AllMusic. Again, excellently recorded, this should be pushed to room pulverising levels, and get the whole street dancing ...
If you want fantastic house rockin' music, just spin Hound Dog Taylor: A Tribute - Various Artists | Songs, Reviews, Credits, Awards | AllMusic. Again, excellently recorded, this should be pushed to room pulverising levels, and get the whole street dancing ...
Digital noise rears its ugly head ...
Bound to be, yep. Perhaps when Frank said CD what he was actually referring to was the unabridged 4 box dCS stack?
Just had a look, sorry, that one would put me to sleep - this is more my style, PETER GREEN Live Black Magic Woman - Splinter Group - YouTube,
....
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The "joke" is that the unit I heard was either a predecessor or something very close to it, in cost ...Bound to be, yep. Perhaps when Frank said CD what he was actually referring to was the unabridged 4 box dCS stack?
dc servo factoid --
The compl-diff was independently invented by J. Curl, as he stated. The DC servo concept as a 'solution' as we know and use it today, was invented by myself and first discussed with Walt Jung. We had just published some work on capacitors in Audio magazine and I suggested eliminating the coupling cap... I had done so and it sounded better. I used the word 'servo' to Walt as it was used and applied to other fields of science. Walt's phono stage with his dc servo design implimentation first appeared in TAA.
These are old subjects of historical interest now and well documented.
THx-RNMarsh
The compl-diff was independently invented by J. Curl, as he stated. The DC servo concept as a 'solution' as we know and use it today, was invented by myself and first discussed with Walt Jung. We had just published some work on capacitors in Audio magazine and I suggested eliminating the coupling cap... I had done so and it sounded better. I used the word 'servo' to Walt as it was used and applied to other fields of science. Walt's phono stage with his dc servo design implimentation first appeared in TAA.
These are old subjects of historical interest now and well documented.
THx-RNMarsh
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Bredren ,
Never stated Kilo-watts, stated Low-Z drive. Now if you plan on building something and seeing you are no Spring chicken
I would not even attempt to do a speaker system unless it's SOTA, why waste time building some little BS avg speaker, my time is more precious than that , might as well be listening to PC speakers like Frank ...
It's like that smarter than everyone dude, building himself an 8watt toooby, then claiming nirvana ...
I thought I had made it clear, but it seems not.
Wayne, while indeed I am far from shy, I TRY to be reaslistic, with varying results.
Sure, I know a lot about power amps compared to a typical DIY hobbyist, but that pales a lot compared to people like Demian, Pavel and John. I am here to learn and, with any luck, pick up a few pointers like Demian made a few posts ago. If I was up to SOTA standards, he wouldn't have had to make them.
They are the professionals in the SOTA range, I am at best a well informed amateur.
In addition to which my requirements are vastly different to yours, far less demanding. As a matter of fact, you are the one and only person I know of who has 1 Ohm speakers.
take your 8 ohm power and apply to 2 ohms .... it will sound better than the other way around with this 2 ohm , 2 ms BS ....
Fine, but you should put a stamp on it, let your inner D roar ...
Well, the multiplication table is simple enough. 100W/8 Ohms is 200W/4 Ohms is 400W/2 Ohms. 100W/8 Ohms is 5 A peak, is 10A peak into 4 Ohms is 20A peak into 2 Ohms.
If I want 20A peak into 2 Ohms, I would need quite a few output transistor pairs to handle that safely on any longer term basis. I agree 2 mS is ridiculously short, a literally better something than nothing "solution". As I said before, 50 mS is the shortest interval I'd consider as realistic.
Just for memory's sake, I'd like to take you back to that German made amp, LAS Mega 1, designed in 1978. The reason I mention it is because those guys had that problem licked even then. They used 1.5 Ohm/17W emitter resistors to make sure the output trannies, 4 pairs of BD 249/250 C (rated at 100V, 125W, 25 A continuous, 40A impulse) never COULD be asked to deliver more than their specs indicated. The whole amp was rated at 150W/4 Ohms and 100W/8 Ohms, with a nice 100 V/uS slew rate, and excpet for one transistor, used off the shelf parts. Unfortunately, in those days (1979), nobody thoght of testing them for 2 Ohm operation. But I bet it could stand up well to that test, and way better than most in its price class.
The point is, I've been considering low impedance aspects ever since then, and that's ben 35 years now. My views, right or wrong, have been put to quite a few tests since then, so I'm not talking off the top of my hat. I maintain that we need to have an amp capable of working into 2 Ohms, but not necessarily on a continuous basis, so long as the limitation to continuous basis are simply cooling considerations. No point chasing something that will quickly burn out one's output stage.
It is my feeling you do not quite see this and similar limitations. One needs to balance the whole design. To make the 2 Ohm continous mark, one needs to:
1. Use DAMN big heat sinks, and a lot of them,
2. Use several output device pairs, which is a hornet's nest in itself to make them work in unison,
3. Use forced air cooling (fans) to control the temperature rise, or
4. Use Class D amps.
I mentioned, and now I mention it again, some weeks ago, a friend and I really powered my system to uncomfortbaly loud levels, approximately 95-96 dB SPL at 3 m, which means 101-102 dB SPL at the usual 1m distance. The power amp PEAKED at just over 70W/8 Ohms nominal, cleanly riding out anything we threw at it. The key point - it never changed its overall tonal balance while doing so. To me, that spells a very good amp because that is a hell of hard act to pull off. Both the Marantz 170 DC and the Citation 24 did it no problemo, as did the Karan integrated, while quite expectedly, the small Philips amp choked.
Now, if my speakers were not 8 but 4 Ohms, there's no telling how it might have worked out. I suspect the Marantz would have started to seriously struggle, but not so the Citation, given that it has a dual mono topology and an effecticely better and stronger power supply system overall.
That's the problem with sweeping statements, they lose all touch with reality, which is very widely varied. In my case, this works in my favor, and in your case, this works against you because it tends to reduce your particular requirements.
Thank you for the historically correct background, Richard. It's best to get this kind of info from people who were actually involved in all that.
There is a note in W. Marshall Leach's first power amp project published in the Audio magazine, in which he says that to the best of his knowledge, the first fully complementary topology he is aware of was launched by James Bongiorno. Hence the misunderstnding.
Glad to set this right.
Please ask WJung. I have a copy of the TAA article but it is on the other side of the planet now. As I recall, there wasnt much made of it in that article but it later produced other articles and detailed math analysis of that first one and variations of the topology. I dont remember that author. (also in TAA archives somewhere). It may helpful to you.
[J.Curl was privy to our discussions about this and has also first person knowledge of the events. John, Walt and I were all close at this period in time.]
THx-RNMarsh
[J.Curl was privy to our discussions about this and has also first person knowledge of the events. John, Walt and I were all close at this period in time.]
THx-RNMarsh
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Gearslutz.com - View Single Post - Discrete Opamps
http://www.gearslutz.com/board/geekslutz-forum/500771-discrete-opamps.html
John, I was going to bring this up earlier.
Your account of the history of this would be interesting.
Dan.
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