Hi,
Who said size does not count. After my divorce I only have a 10 inch (woofer), sadly, but I expect this soon to get back the normal 15 - 18 Inch (woofer) any real man should aspire to...
I expect I'll do my next speaker as 2-Way, 15" plus a Hornloaded Magnetostat with 600Hz crossover and 98dB/2.83V/1m efficiency. Probably add a subwoofer to this, something with a 21"..24" driver should do nicely.
Ciao T
You have this wrong , it's those who say size doesn't count that's hiding something ...
Who said size does not count. After my divorce I only have a 10 inch (woofer), sadly, but I expect this soon to get back the normal 15 - 18 Inch (woofer) any real man should aspire to...
I expect I'll do my next speaker as 2-Way, 15" plus a Hornloaded Magnetostat with 600Hz crossover and 98dB/2.83V/1m efficiency. Probably add a subwoofer to this, something with a 21"..24" driver should do nicely.
Ciao T
Hi,
True. At the time I could only take russian Fet's, if any, as I was stuck behind the great wall of Berlin. Actually, we still used tubes where now one would use a FET... ;-)
While I could, I think I plow ahead with my current project.
I did a few "sanity check" comparisons with other topologies I can think of and what I call "Sir Pottymouth" starts to look quite horrorshow, according to my particular set of requirements.
Actually, here a fun part.
In several of these topologies (including folded cascode CM loaded and dual differential with 2nd one CM loaded Locanti Style) I tried the inner feedback loop on/off.
In ALL of them the answer at least from Tina-Ti is unambigous.
Less local loop feedback = increased upper harmonics for both 1KHz and high frequencies like 50KHz, but lower THD...
It will be interesting to see what LT-Spice pronounces.
BTW, I would argue that what I am working on has a lot of parallels with what LAS did in the Mega 1. You would not possibly happen to have the 1980 Funkschau article in which it was described in .pfd format, would you. It seems that you are one of two people on the whole web that actually know this Amp at all!
I must say that I am by far less impressed with these, compared to the LAS Mega 1...
Ciao T
True. At the time I could only take russian Fet's, if any, as I was stuck behind the great wall of Berlin. Actually, we still used tubes where now one would use a FET... ;-)
While I could, I think I plow ahead with my current project.
I did a few "sanity check" comparisons with other topologies I can think of and what I call "Sir Pottymouth" starts to look quite horrorshow, according to my particular set of requirements.
Actually, here a fun part.
In several of these topologies (including folded cascode CM loaded and dual differential with 2nd one CM loaded Locanti Style) I tried the inner feedback loop on/off.
In ALL of them the answer at least from Tina-Ti is unambigous.
Less local loop feedback = increased upper harmonics for both 1KHz and high frequencies like 50KHz, but lower THD...
It will be interesting to see what LT-Spice pronounces.
BTW, I would argue that what I am working on has a lot of parallels with what LAS did in the Mega 1. You would not possibly happen to have the 1980 Funkschau article in which it was described in .pfd format, would you. It seems that you are one of two people on the whole web that actually know this Amp at all!
I must say that I am by far less impressed with these, compared to the LAS Mega 1...
Ciao T
You have this wrong , it's those who say size doesn't count that's hiding something ...
On a nudist beach, many bluffs in life are debunked.
Hi,
True. At the time I could only take russian Fet's, if any, as I was stuck behind the great wall of Berlin. Actually, we still used tubes where now one would use a FET... ;-)
While I could, I think I plow ahead with my current project.
I did a few "sanity check" comparisons with other topologies I can think of and what I call "Sir Pottymouth" starts to look quite horrorshow, according to my particular set of requirements.
Actually, here a fun part.
In several of these topologies (including folded cascode CM loaded and dual differential with 2nd one CM loaded Locanti Style) I tried the inner feedback loop on/off.
In ALL of them the answer at least from Tina-Ti is unambigous.
Less local loop feedback = increased upper harmonics for both 1KHz and high frequencies like 50KHz, but lower THD...
It will be interesting to see what LT-Spice pronounces.
BTW, I would argue that what I am working on has a lot of parallels with what LAS did in the Mega 1. You would not possibly happen to have the 1980 Funkschau article in which it was described in .pfd format, would you. It seems that you are one of two people on the whole web that actually know this Amp at all!
I must say that I am by far less impressed with these, compared to the LAS Mega 1...
Ciao T
I used to have it, but unfortunately, it was in that one crucial carborad box which got lost during my last move in 1989.
Believe it or not, I drew that from memory only. We elephants remember.
I think any comparison between the LAS amp and what you are doing today (if that's what you alluded to) is really quite menaningless and not really possible.
In those days, the LAS was a good example of sound technical thinking coupled with a sense for the practical and, I'm willing to bet, some hard experience in the field. But that was what it was in those days.
In the meanwhile, we have all hopefully learnt a thing or two, in the meanwhile we have better both passive and active components and we certainly have much better measuring gear. New circuitry was developed and evolved, and is still evolving. All very normal and natural.
However, what seems to be lost these days is the realization that what did sound good in those days will still sound good today - not top of the state of the art any more, bettered by a few, but still good. There seems to be an assumption that a say 30 years old gear cannot sound good any more; indeed it can't as is, but when overhauled properly and readjusted, it will return to its glory of old and very often, put much of the modern gear to shame. Sometimes, vintage makes you wonder where has the industry been over the last 30 years.
As for the East/West thing you keep mentioning, I will not comment, but simply recall my own experience. In Munich in 1990, as a guest of Compaq, I talked to their leading staff members, where only the top boss was "American" (actually, he was from Zagreb, Croatia), the others all bright young men from Germany.
One of them told me that they definitely preferred cooperating with programmers from the ex-Eastern Europe, and that for a simple reason: they had as low as you can go machines, often with two 5.25" floppy drives only and just a little memory, so the programs they wrote were necessasiry small, compact and fast executing, on all points much more so than their Western counterparts, all of whom had all of the 640 kB DOS allowed for and all had at least one hard disk in their machines.
So it was with you, I'll wager. You had to use your head far more for the same effect as your western counterparts because you had so much less than they did. This made you sharper than most so now you got used to it, you are a catana dancing with pocket knives in many cases. And you are inquisitive, a trait lost far too many times with the young generation everywhere.
Abundance makes us lazy, a shortage of everything makes us sharp. It's that simple.
People like our own John here, James Bongiorno, Matti Otala, Nelson Pass, these are the free thinkers, they are the exceptions which confirm the rule. True, there are other, less well known or even personally unknown people like that, but once again, all together they are the vast minority - and it's always the minorty which pushed the limits. Always.
It would appear somebody from LAS was a member of this minority. Or so I like to think. As you will see, the Marantz team also had somebody like that.
I would say that the limiting factor was rather the output triple
that could burst the whole thing in flame if poor compensations
are implemented , as seems to be the case with this bizarre amp.
Seems that you like anything that make a differentiation be it
a useless and non efficient one...
Besides , the input stage is not degenerated at all , surely an
other plus to improve stability....
Thorsten, does the schematic of Harman/Kardon 870 power amp vaguely remind you of something?
The other is the power amp schematic of Marantz' 300 DC, a 2*150W power amp. It's exactly the same schematic as several of their other models (with different values, of course), including my integrated amps. Their sound I really love very much.
Marantz to the left, HK to the right.
The other is the power amp schematic of Marantz' 300 DC, a 2*150W power amp. It's exactly the same schematic as several of their other models (with different values, of course), including my integrated amps. Their sound I really love very much.
Marantz to the left, HK to the right.
Attachments
Really? It may interest you to know that the Marantz schematic dates back to the first dates of production, January 1978.
There was obviously serious work done to get this stable. 3pF cap inside one of these big boxes can be achieved by moving a wire harness asside. The R/C step network in the Vas was certainly optimized with some experimentation (115pF?). That's a standard value for max range on trimmers.
Nothing more frustrating than putting your finger on a node and making a circuit behave perfectly and not being able to find a cap put anywhere that does the same thing.
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Indeed it does, and "it" is the Harman/Kardon 680 integrated amplifier, rated at 85/130W 8/4 Ohnms, using only 12 dB of global NFB.
I've had it for 13 years now, and can attest to its very lively sound. Compared to him, about half of its competitors sound positively dead.
Wrong!
They were the last series designed in the U.S.A. and manufactured in Japan, by what was later to become the one and only Marantz.
Wrong again on plural "subcontractors" - Marantz never had more than one, which was later renamed Marantz Japan Inc.
About others, you are right. Bob Carver's products, for example, were actually manufactured by Benytone and Matsushita of Japan.
Entire series of products markeked in Germany as Saba, BASF, etc were OEM-ed from Sanyo Marubeni of Japan.
Switzerland's Lenco also went down that road, and at one point, they offered generic products from Harman International, just as did Uher of Germany, which was owned by Harman.
There was obviously serious work done to get this stable. 3pF cap inside one of these big boxes can be achieved by moving a wire harness asside. The R/C step network in the Vas was certainly optimized with some experimentation (115pF?). That's a standard value for max range on trimmers.
Nothing more frustrating than putting your finger on a node and making a circuit behave perfectly and not being able to find a cap put anywhere that does the same thing.
Bull's eye, Scott, that drove me nuts.
BFT28A and 115 pF were the eternal problems of that amp.
However, things change. These days, you can't find BC414/416 C anywhere, they are still made by a small US (???) company, so like it or not, you have to stick in the nearest equivalent, which would be BC 550/560 B. You have to replace the BFT28A, and that again is more than likely to change the value of that 115 pF cap.
Obviously, depending on what comes in instead of the BFT28A, I would venture a guess that 115 pF would become something more like 110 pF, even 100 pF. Then again, there's the PC board outlay, quality, copper thickness, ...
But that's a part of the fun of it.
With a point to point soldering , you could as well try to re shapeNothing more frustrating than putting your finger on a node and making a circuit behave perfectly and not being able to find a cap put anywhere that does the same thing.
the circuit , litteraly...
That said ; i didnt know that i wasnt the only one to put fingers
on sensitive nodes to check stability...
Hi,
Well, Bart Locanthi pioneered the output tripple (and the dual differential for that) in the JBL SA-600 in 1967...
Not really. I find most differentiations rather useless...
I do think about things and as a rule, i do not simply take what is passed down to me and the rest of the great unwashed by "Authority" (Tis prob'ly the most crucial trait that comes from growing up in the east).
And thi nking for myself, I often come different conclusions.
Furthermore, what you find efficient is not what I consider efficient or desirable, in case this message still has not percolated down.
You make your designs according to certain sets of parameters, which are basically just an assembly of beliefs, unfounded in any reality or proof which is fine with me.
You then judge everyone else's work on how well it conforms with your particular set of parameters, or shall we say prejudices. This too is fine if you'd care to include a suitable qualification in your remarks. However you present your views as if they carry authority, which may only be conferred to them by providing positive proof, which alas is AWOL.
Yes, for what it is worth, I should have liked to see some input degeneration. The LAS Mega 1 is not something which we could consider the best possible arrangement, knowing what we do now, still, it seems quite an interesting design and one that will do well subjectively, in my view.
Ciao T
Well, Bart Locanthi pioneered the output tripple (and the dual differential for that) in the JBL SA-600 in 1967...
Not really. I find most differentiations rather useless...
I do think about things and as a rule, i do not simply take what is passed down to me and the rest of the great unwashed by "Authority" (Tis prob'ly the most crucial trait that comes from growing up in the east).
And thi nking for myself, I often come different conclusions.
Furthermore, what you find efficient is not what I consider efficient or desirable, in case this message still has not percolated down.
You make your designs according to certain sets of parameters, which are basically just an assembly of beliefs, unfounded in any reality or proof which is fine with me.
You then judge everyone else's work on how well it conforms with your particular set of parameters, or shall we say prejudices. This too is fine if you'd care to include a suitable qualification in your remarks. However you present your views as if they carry authority, which may only be conferred to them by providing positive proof, which alas is AWOL.
Besides , the input stage is not degenerated at all , surely an other plus to improve stability....
Yes, for what it is worth, I should have liked to see some input degeneration. The LAS Mega 1 is not something which we could consider the best possible arrangement, knowing what we do now, still, it seems quite an interesting design and one that will do well subjectively, in my view.
Ciao T
Yes, that's a good way to lose credibility. I mean, it's fine to have a different opinion, but if you want to be believed, it takes a LOT more than just saying "it ain't so".
Which is what I originally said, but in a different way. Being able to adjust DC offset in such designs is usually done by installing two resistors anda trimmer in parallel in the input stage. Not necessarily the only way, there are others, but that one is quite typical. It would also introduce degeneration, how much depends on what we want. Also resistors between current mirror tranistors and the plus power line.
And yes, it sounds really good, to me that's not an opinion, but an experience.
...
That said ; i didnt know that i wasnt the only one to put fingers
on sensitive nodes to check stability...
I concluded long ago that the engineer's finger is the electrostatic equivalent to ferrite beads.
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