Correction - I do NOT sell them any more, I used to. I am too old to do manufacturing in my country, where everything is a big problem. That's for the young.
For the recond, I used to offer three versions: one using BJTs, one using FETs on the input and MOSFETs at the output, and one using tubes. I did not design the tube version, an associate of mine did.
Personally, I like the BJT version best, so I kept one of those for myself, as well as the original trial version, I'm a bit sentimental.
That goes for Jean Hiraga Le Monstre and JLH class A. This little amp is mighty cunning. It uses the source device as drive current for the bootstrap CCS.The output stage is a SE class A complimentary feedback pair with a loop of feedback around itself. The distortion is about <0.02 %. As it is SE class A there are no switching issue.
The feedback is merely for linearity and low output impedance. Slewing will not be an issue. The feedback is summed at the input not in the Tr1 emitter. As the sources I intend to use are low output impedance it stands a chance.
The design brief is to be supper small and sound better than an iPod. The rub is it will be fed by an iPod. As a CfbP can sing almost rail to rail it helps ( 3 V pk to pk from 3.7V DC = > 1 Vrms ). As the aimed for input impedance is about 2K it will ask less of the iPod output stage. As the iPod is designed for 32R then 2K it might even find class A operating point in the iPod ( bias overlap ). Thus it might just be possible to sound better than the original ( just). Total stability should be guaranteed which I supect is not true of iPod op amp. That could be the vital game changer.
In about 1977 Bob Stewart put it in my mind that ever time a signal entered a transistor something is lost. Bob suggested by careful design a specification can be met with fewer devices. His last belief being that the measured results may show no difference worth speaking of. The object of the exercise being to win customers by offering " musicality". That is a fluidity and depth without a feeling of a thin paper curtain between the music and the listener.
Wireless World ran a feature in valve days comparing a 3 and 4 valve circuit of identical spec (their words). The 4 valve was an off the peg design. The 3 valve had to use much calculation to get there. Some positive feedback used. W W were not interested in the ultimate sound. What was shown is that simple design is far from simple. As they said it would in commercial terms pay off. PYE Mozart comes to mind as the pinnacle of economical design. Onguku was inspired by it.
The design concept I speak of is East to West signal path. House keeping circuits run North South. To me where possible a house keeping circuit is a resistor. I can design a CCS at the drop of a hat in my sleep. If I can avoid one I do. Sometimes for a very practical reason. Less PCB space giving closer to Dead Bug performance. If you build Dead Bug often the PCB one is less good. As PSU most often is external, a separate PSU to the quieter stages might be easier to do and a better use of cheap semiconductors. CVS via a resistor becomes CCS or so the text books say. It will be especially true for conventional op amp style amps.
The little headphone amp will help the battery life of the iPod (or whatever). Itself 15 hours per recharge. If I were to add one transistor it would be the CCS. I would use an LED reference as it would also be power on inductor. The reason to do it is I can then almost guarantee the iPod will be in overlap bias class A. One LED to two CCS. The LED CCS is thoughts to offer better HF PSRR. At 20 kHz on the Hitachi LTP. PSRR when resistor - 92 dB, CCS two transistor -100 dB, LED -127 dB. Theses figures are above audio band.
Nige, why don't you take a lesson from Nelson Pass and do one of those "one MOSFET is all it takes" amps?
To avoid copyrights, you can call it "Buddha", "Allah" or "JC".
Distortion seems a bit high. The design brief is to be better than the original. I don't mind doing a Jesus on that, a lie would be too much. Jesus said Render unto Caesar etc. One has to draw a line at what one considers to be a lie. Better than the original can just about be done but requires considerable walking on water. A bootstrap does that so we sometimes can. Negative feedback also comes close. A haircut is my personal favourite.
Jesus wasn't even his name I suspect? Who can you trust in this world ?
As far as I know they are older and being wired stereo is the only difference. They are used because they always have been used. Our Beyer rep was Mr House . The delightful gentleman always carried that model in stock for historic reasons. If you listen to the Bruckner No 9 recorded on my birthday in 1944 Karajan through those phones you will have a rare insight. Musically it rates as one of the better pieces I have ever heard. Is Bruckner some composer hey? Beethoven + Brahms + Wagner = Bruckner?
Joachim. If you don't mind me saying your speakers have a fluidity that few equal. As I was saying yesterday hearing is not exactly about these tests. It is being able to know when something is like real music. That seems to endure if we have it. We can measure what we don't hear and ask friends if we doubt things. Your speakers used for the great turntable shootout in Munich look so very USA meets Germany meets Denmark circa 1978. They didn't sound that way and melted out of my thoughts when listening. They looked boring and sounded sublime. Was the boring deliberate? I wouldn't do better so not a criticism. I guess JBL does Spendor is how they looked. I loved them for that so please do not be offended. It's a big shock when the sound defeats what the ears thought they would hear.
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Frankly, I don't think that little thingie is comparable to Hiraga, for example. Hiraga did simplify the signal path, but overall, he kept his feet on well trodden paths. Stuck to input-VAS-driver-output scheme.
...
That's very easy to agree with, HOWEVER, there are twists which simply cannot be done with a few transistors, or not as well.
Does it not strike you that most (though not all) well regarded amps over the years used a lot of semiconductors, certainly way over what the DIY crowd considers as reasonable?
You have already spoken your mind about Krell amps, and here I beg to differ. I will easily agree that they are not as unselective of speakers as the makers would have us believe, but I have heard them in their full glory more than once. Well, in his 90ies series, d'Agostino used 118 transistors just for the input stage, meaning input and VAS.
We both know the classic amp outlay uses about 6 transistors at most for the input stage and VAS, if you are willing to work your bakcside off to get just the right outlay, so your VAS boils down to just one transistor, and that with a small Miller compensation cap so as not to compromise the slew rate. If you use resistors for your CCS stages, that can be brought down to 4.
It has been done often enough. However, in comparison with a slightly less frugal diet, all that will work even better, and by "work" I mean sound better. After all, we actually have learnt from the good, old days, nd the prices of transistors have gone to the dogs, so there is no more compelling reason to save on their prices - as was once the case, in addition to a much smaller selection capabalitiy. These days, you have specialized transistors which scratch you behind the ears.
My point is, extremes generally don't work too well. Too little is just as bad as too much.
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On the strength of the above statement, I don't think so for two reasons.
First, Krell amps are often praised for "a bass to die for", so I think bass would be of crticial value to Mr d'Agostino. Also he stated in the said interview that he uses headphones for evaluation because dirt and grime live low down in amps, or some such. Electrostatics are not exactly know for their stunning bass lines.
And second, to use electrotatics he would need some kind of something in between to make them work. Throwing whatever in between sort of defeats his purpose, doesn' it, as it's an extra layer in between?
But this is conjecture only.
The Elephant in the room with that idea is. No human on the planet supposedly will hear the distortion. The point of the circuit is ? I have so little space and do not want an op amp solution. 4 transistors 0.04 % THD class A SE seems an OK solution. I see a transistor as a lie in the circuit. The more the transistors the more the lies. Equally a circuit not able to do it's job is a lie. What we all do is like to practice our skills. Here it would be highly damaging to my design goal. I would guess the THD of headphones to be 0.2% best typical. As I said I will use 4 transistors as I don't want the source providing the CCS current. I would hazard a guess this circuit will considerably outperform the Krell with a dropper resistor.
Aircraft can not be built without respect to weight. My training was at an RAF college. There was a small belief that UK aircraft were safer because we worked to a higher proof stress. This was not born out. Aircraft have to be built to the facts. Recently a glass fibre aluminum composite was used. Carbon fibre in some ways not giving the required things on the worlds largest passenger aircraft. Glad to see they can still think logically and not go with the flow.
Aircraft can not be built without respect to weight. My training was at an RAF college. There was a small belief that UK aircraft were safer because we worked to a higher proof stress. This was not born out. Aircraft have to be built to the facts. Recently a glass fibre aluminum composite was used. Carbon fibre in some ways not giving the required things on the worlds largest passenger aircraft. Glad to see they can still think logically and not go with the flow.
If it was the DT-48, that headphone still sells for over $400 today and is still used in some studios and at audiologists.
Last time I went to an audiologist for custom IEM ear impressions, here in Asia, I saw they had a Beyer DT-48A I think it was.
It doesn't look very good, not the A model at least, the E model looks much better. Then there's an S model and different variations over the years.
If a studio still buys a DT-48E made in 2014, they do it for a reason.
Not sure what the exact reason is.
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Nige, as you know i am a furniture designer.
My ethos is " design is invisible " so no, i have no problem with boring.
Did more spectacular looking pieces but many customers still prefer the simple box shape.
Retro feelings ?
When you think the Bayer is fine thats fine with me too.
When the swiss are using them i already thought they had good reason.
So it is a kind of industry standart.
My ethos is " design is invisible " so no, i have no problem with boring.
Did more spectacular looking pieces but many customers still prefer the simple box shape.
Retro feelings ?
When you think the Bayer is fine thats fine with me too.
When the swiss are using them i already thought they had good reason.
So it is a kind of industry standart.
The headphones they used to test my ears looked a bit like those but even more ancient when i remember correct :SOLD: Vintage Beyerdynamic DT48 5 Ohm (Beyer DT48A)
Do you know the model number of those speakers ? It was when testing Transrotor turntable costing as much as a nice house. I liked the Technics 1210. More my cup of tea. Shame we did not have a Lenco GL 75 to try. That could have upset many people. Can you imaging cost of a house verses off of the garbage tip? I suspect garbage tip could win as it might have more verve? You may also remember we used Clear Audio cheap phono stages? They were perfectly OK considering how I thought they would be awful. Mackintosh power amps. The Clear Audio I think is almost the Douglas Self design.
Those 1936 headphones.
https://www.facebook.com/notes/beye...years-beyerdynamic-experience/214690631903923
Ah, I've never seen the model you linked before, with "W. Germany" on the side and a shiny, metallic red finish. An ancient Beyer logotype as well.
I like the current DT-48E model.
Here's a few pictures of the driver http://alexmod.do.am/forum/14-2-1
Side note, anyone considering a custom IEM, I recommend to avoid China.
In my personal experience, well, let's just say I sent them a custom IEM, then after much hassle, they sent the insides back to me, only the insides, my C-IEM was ruined.
They are not ugly at all, in my view, but they are too small for my taste. And WAY too expensive.
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Alright, I finally have time to answer this, time to underline a few points.
I apologize, for this really long post!
Just continue as usual and nevermind me, if you prefer.
1 - I'm not sure, like you say, we can't really be certain at all without evidence.
I think we need some kind of intuition, hunches, technical theories or perhaps have some faith in our illusions, to arrive at the ideas of what to test at all.
We need to imagine how audio works from A to Z and imagine how to improve it to the fullest to achieve the highest accuracy or the highest detail ever served.
If that accuracy is within reality or not, well, that depends on the focus of the listeners and how revealing the test equipment is.
I am honestly not sure how revealing all the usual test equipment is, let alone all the blind tests.
Let's take capacitors.
Despite a string of null results in testing and an internet full of people saying there are no differences visible in advanced equipment, equipment which far excel human hearing......
Later, I see a magazine article, which shows clear differences, differences which should be clearly audible, there's high spikes up to -45 dB for example.
How does this make any sense?
In fact, personally, it only instills a slight disbelief in the internet, the null results and the usual test equipment.
Links to the magazine articles on capacitors......
http://www.scribd.com/doc/2610442/Capacitor-Sound
Pro Audio Design Forum • View topic - Cyril Bateman Capacitor Sound Archive
2 - Yes, you are perfectly correct...... however, I may lack the sophistication to actually address the concerns.
I may be concerned about penguins, I'm not sure if I have the sophistication to actually address them!
I'll try to highlight my concerns, they are......
X - Do capacitors really sound or feel different and unique? The links I provided seem to say so.
Y - Do op-amp and DAC chips sound or feel uniquely different? Is there a unique difference between, let's say, AD8610 and OPA627?
Y.1 - AD8610 and OPA627 functioning perfectly, at their higher performance level?
Y.2 - AD8610 and OPA627 in nearly any piece of equipment, not functioning correctly, are there still unique differences here?
-- Side-note, I believe I can hear the difference in Y.1 clearly, no A/B necessary. I'd like to prove this somehow, someday.
Z - Does the typical AB or ABX test remove differences?
Z.1 - Are the tests truly neutral, or are they sometimes aiming for null results, due to the preconceived idea, that a null result is the only one acceptable to them?
See example......
Z.2 - Does the typical AB or ABX test remove real differences?
I accept that this paper is not very valid, I looked closer at it and they only asked each participant for their preference or x/y/z value once.
Plus, it's performed by the company which is selling the capacitors.
However, it is at least something new, something fresh.
The point is, they say their ABX testing nulled and their preference testing prevailed......
http://www.partsconnexion.com/t/claritycap/Reseach_Summary.pdf
Another example......
Another......
Personally, I don't believe in SACD or DXD very much at all, I don't even believe in FLAC very much!
Any differences they have, are too slight for me to really care about.
Pretty much every single DAC I've heard sounds different though, sometimes really different!
I remember one day, I tried comparing my little tiny portable Sony player to my desktop DAC, by switching the cable really fast.
I was playing the same track at around the same volume, I pressed play on my PC and the Sony player at the right time so the track time would coincide.
Suddenly, when I switched the cable, they sounded the same! It was unbelievable! Ever since that day, around two years back now, I've been quite skeptical of this kind of switching in AB and ABX.
These are just my views. I could be in error, if I'm inside an advanced illusion, but then that illusion is pretty advanced!! It means my tiny Sony player is all I really need and these advanced desktop DAC's are nonsense!
I think your test sounds fine, if you are looking for a pretty large difference.
If the difference is tiny, I'm not sure if you will find it.
I have another idea, you make people sleep under fluorescent light and LED light, or constant LED and flickering LED, for a few weeks.
They are not aware of what the test is.
As soon as they wake up, they have to play a game on their computer for 10 minutes to test their reflexes.
After a few weeks, you switch the lights, so flickering LED is changed to normal LED.
At the end, you look at their reflex scores.
You can also ask them to write little notes, like, how they felt when waking up, during the day, normal or different.
I don't think I have any specific difficulty. I think I prefer my apartment with LED light, rather than fluorescent light, it could just be expectation effect.
I didn't like the way the fluorescent lights looked, I couldn't see the actual flicker, but you have to admit they don't look like LED and especially not incandescent.
Actually, there's a Starbucks near me full of fluorescent lights, I don't mind it, but I've always thought it would look much better with LED light or incandescent, especially for a multi-national corporation like that where I need to pay $4.15 for my Venti Java Chip.
'K, let us note that the believers in subliminal advertising could not step up with positive results, from 1957 until 2011!
They tried to and it never worked, so they had to rely on faith.
I know, that's a special case, but I think it deserves a highlight.
|
Alright, I finally have time to answer this, time to underline a few points.
I apologize, for this really long post!
Just continue as usual and nevermind me, if you prefer.
Let me provide an example.
- LED lights which flicker and LED lights which don't, zero flicker.
You can not visually ABX the difference, since you can not --see-- any difference.
However, you can still --feel-- the difference, since it is interacting with you subliminally.
Whether you believe this statement to be true or not, how would one evidence it?
1 - I'm not sure, like you say, we can't really be certain at all without evidence.
I think we need some kind of intuition, hunches, technical theories or perhaps have some faith in our illusions, to arrive at the ideas of what to test at all.
We need to imagine how audio works from A to Z and imagine how to improve it to the fullest to achieve the highest accuracy or the highest detail ever served.
If that accuracy is within reality or not, well, that depends on the focus of the listeners and how revealing the test equipment is.
I am honestly not sure how revealing all the usual test equipment is, let alone all the blind tests.
Let's take capacitors.
Despite a string of null results in testing and an internet full of people saying there are no differences visible in advanced equipment, equipment which far excel human hearing......
Later, I see a magazine article, which shows clear differences, differences which should be clearly audible, there's high spikes up to -45 dB for example.
How does this make any sense?
In fact, personally, it only instills a slight disbelief in the internet, the null results and the usual test equipment.
Links to the magazine articles on capacitors......
http://www.scribd.com/doc/2610442/Capacitor-Sound
Pro Audio Design Forum • View topic - Cyril Bateman Capacitor Sound Archive
2 - Yes, you are perfectly correct...... however, I may lack the sophistication to actually address the concerns.
I may be concerned about penguins, I'm not sure if I have the sophistication to actually address them!
I'll try to highlight my concerns, they are......
X - Do capacitors really sound or feel different and unique? The links I provided seem to say so.
Y - Do op-amp and DAC chips sound or feel uniquely different? Is there a unique difference between, let's say, AD8610 and OPA627?
Y.1 - AD8610 and OPA627 functioning perfectly, at their higher performance level?
Y.2 - AD8610 and OPA627 in nearly any piece of equipment, not functioning correctly, are there still unique differences here?
-- Side-note, I believe I can hear the difference in Y.1 clearly, no A/B necessary. I'd like to prove this somehow, someday.
Z - Does the typical AB or ABX test remove differences?
Z.1 - Are the tests truly neutral, or are they sometimes aiming for null results, due to the preconceived idea, that a null result is the only one acceptable to them?
See example......
Z.2 - Does the typical AB or ABX test remove real differences?
I accept that this paper is not very valid, I looked closer at it and they only asked each participant for their preference or x/y/z value once.
Plus, it's performed by the company which is selling the capacitors.
However, it is at least something new, something fresh.
The point is, they say their ABX testing nulled and their preference testing prevailed......
http://www.partsconnexion.com/t/claritycap/Reseach_Summary.pdf
Another example......
Another......
canonical said:
Personally, I don't believe in SACD or DXD very much at all, I don't even believe in FLAC very much!
Any differences they have, are too slight for me to really care about.
Pretty much every single DAC I've heard sounds different though, sometimes really different!
I remember one day, I tried comparing my little tiny portable Sony player to my desktop DAC, by switching the cable really fast.
I was playing the same track at around the same volume, I pressed play on my PC and the Sony player at the right time so the track time would coincide.
Suddenly, when I switched the cable, they sounded the same! It was unbelievable! Ever since that day, around two years back now, I've been quite skeptical of this kind of switching in AB and ABX.
These are just my views. I could be in error, if I'm inside an advanced illusion, but then that illusion is pretty advanced!! It means my tiny Sony player is all I really need and these advanced desktop DAC's are nonsense!
I think your test sounds fine, if you are looking for a pretty large difference.
If the difference is tiny, I'm not sure if you will find it.
I have another idea, you make people sleep under fluorescent light and LED light, or constant LED and flickering LED, for a few weeks.
They are not aware of what the test is.
As soon as they wake up, they have to play a game on their computer for 10 minutes to test their reflexes.
After a few weeks, you switch the lights, so flickering LED is changed to normal LED.
At the end, you look at their reflex scores.
You can also ask them to write little notes, like, how they felt when waking up, during the day, normal or different.
I don't think I have any specific difficulty. I think I prefer my apartment with LED light, rather than fluorescent light, it could just be expectation effect.
I didn't like the way the fluorescent lights looked, I couldn't see the actual flicker, but you have to admit they don't look like LED and especially not incandescent.
Actually, there's a Starbucks near me full of fluorescent lights, I don't mind it, but I've always thought it would look much better with LED light or incandescent, especially for a multi-national corporation like that where I need to pay $4.15 for my Venti Java Chip.
'K, let us note that the believers in subliminal advertising could not step up with positive results, from 1957 until 2011!
They tried to and it never worked, so they had to rely on faith.
I know, that's a special case, but I think it deserves a highlight.
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Makes perfect sense to me. By the repetition, you steadily built up a short term memory image of what the music piece was about, which had all the qualities of the best version of it, presumably the 'proper' DAC's rendering,
. Finally, the brain was able to overlay the 'inferior' replaying of the piece with the optimum, internally built up version - your mind 'masked' the deficiences of the poorer version, it interpolated the extra qualities it knew should be there.So, as a parlour game these ABX exercises might be OK, but it doesn't help resolve what's going on when you listen to music replay in the normal fashion,
- once only, all the way through ...
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