I hate to break it to you but AD797s are just not that magical. I put two of them next to a sink full of dirty dishes and they only cleaned half of them! 🙂
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Relief!
I don't know if any of y'all have seen this, but I am so relieved, I just found out that there can be no problems with digital audio, even at 44.1KHz/16bit:
Xiph.Org Video Presentations: Digital Show & Tell
Phew! When I think of all the time I have spent worrying abut it...
Sorry, Bowie dying ruined my week, so I wanted to ruin yours...
Howie
I don't know if any of y'all have seen this, but I am so relieved, I just found out that there can be no problems with digital audio, even at 44.1KHz/16bit:
Xiph.Org Video Presentations: Digital Show & Tell
Phew! When I think of all the time I have spent worrying abut it...
Sorry, Bowie dying ruined my week, so I wanted to ruin yours...
Howie
Since you're one of the smart guys here, blessed with experience and common sense, I'm really curious about your specific critiques. This is usually a pretty reliable source, but if they got things wrong, I'd really like to understand what the errors are.
Why did-you say this ? They don't suffer from secondary breakdown, so they are safer than BJT. Just stay in the security area. If you need more power, just multiply them, with the benefit to reduce crossover distortion.
Oh, and some more advantages, they are fast by nature, and around 100 /150mA of quiescent, don't need any thermal compensation. And > 100 mA is good to get an amp working at class A at normal listening levels.
Lateral ? Hitachi type .........
A whole other world than I.R. types ......
You can have 0 feedback and maintain decent specs ...
Why settle for one or the other.
http://www.diyaudio.com/forums/pass...sults-comments-suggestions-2.html#post1541760 (1987)
http://www.diyaudio.com/forums/pass...sults-comments-suggestions-2.html#post1541760 (1987)
Relief!
I have wasted so much on hi-fi gear...The video proves a 10-year old POS DA interface transfers audio perfectly. Or maybe steady tones are not audio...sorry this attempt at a joke has gone stale, I apologize.
Having performed the experiments he does myself 25 years ago using Sony 1630s and others, I have no issues with the theory as demonstrated in the video, however I do have issues with a few unspoken assumptions:
1) That all music is digitized at each stage to optimize peak levels just under digital FS.
2) That much average listening levels involve all 16 bits and therefore the acoustic noise floor is ~15 bits lower (after the addition of dither). Much music has a crest factor of 20dB or more, so the effective number of bits being used during much of the program uses more like 12 bits or less. That it can sound as good as it does is a testimony to the effectiveness of dither.
3) That all algorithms present in digital equipment treat the signals in a way that does not compromise them.
4) That engineers like the guy in the video who believe that a simple 16-bit 44.1KHz system can do no wrong will not pay adequate attention to the analog stages necessary to get the signals in and out of the system without degradation. I have personal experience with this one, there is a certain conceit and disdain for audio which some otherwise skilled digital engineers have. They then assume to make a perfect piece of audio equipment is child's play. The resulting circuitry can be surprisingly poor.
But this is just repeating what we have been taking years in this forum discussing. I return you to your educated and erudite conversations already in progress...I'm off to do transmitter maintenance.
Cheers & 73,
Howie - WA4PSC
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
WXYC Chapel Hill, North Carolina - 89.3 FM
I have wasted so much on hi-fi gear...The video proves a 10-year old POS DA interface transfers audio perfectly. Or maybe steady tones are not audio...sorry this attempt at a joke has gone stale, I apologize.
Having performed the experiments he does myself 25 years ago using Sony 1630s and others, I have no issues with the theory as demonstrated in the video, however I do have issues with a few unspoken assumptions:
1) That all music is digitized at each stage to optimize peak levels just under digital FS.
2) That much average listening levels involve all 16 bits and therefore the acoustic noise floor is ~15 bits lower (after the addition of dither). Much music has a crest factor of 20dB or more, so the effective number of bits being used during much of the program uses more like 12 bits or less. That it can sound as good as it does is a testimony to the effectiveness of dither.
3) That all algorithms present in digital equipment treat the signals in a way that does not compromise them.
4) That engineers like the guy in the video who believe that a simple 16-bit 44.1KHz system can do no wrong will not pay adequate attention to the analog stages necessary to get the signals in and out of the system without degradation. I have personal experience with this one, there is a certain conceit and disdain for audio which some otherwise skilled digital engineers have. They then assume to make a perfect piece of audio equipment is child's play. The resulting circuitry can be surprisingly poor.
But this is just repeating what we have been taking years in this forum discussing. I return you to your educated and erudite conversations already in progress...I'm off to do transmitter maintenance.
Cheers & 73,
Howie - WA4PSC
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
WXYC Chapel Hill, North Carolina - 89.3 FM
Esperado, the American vertical mosfets made over the last 35 years have not had the safe area that the Hitachi lateral mosfets have. They are actually WORSE than the best quality bipolars overall. The Hitachi mosfets have good safe area but have limited peak current capability. This means that twice as many must be used to make very powerful amps in order to supply adequate peak current.
I'm pretty sure Monty isn't suggesting recording/mixing/mastering in 16/44
the crit is over the "hi res" hype for consumer digital distribution, the common chatter, marketing claims about why hi res is needed by the consumer
in addition to knowing a lot of the Psychoacoustic research, he does have considerable practical listening experience himself from his Ogg Vorbis development days, supervised other testers, debugging their listening equipment, background noise interference...
the crit is over the "hi res" hype for consumer digital distribution, the common chatter, marketing claims about why hi res is needed by the consumer
in addition to knowing a lot of the Psychoacoustic research, he does have considerable practical listening experience himself from his Ogg Vorbis development days, supervised other testers, debugging their listening equipment, background noise interference...
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8 amps is peanuts, jacco. I would have to use 18 pairs of Hitachi mosfets to get to what we get with 9 pairs/channel with bipolar. With my latest design I would have to use 28 Hitachi mosfets/channel. Is this reasonable? Then, there is the low gm voltage loss problem.
Mr. Curl,
you'd have to use 18 anyway, half the Pd of the 200W Sanken MT200.
[If it's 8 amps (7 for the 100W types), why values higher than 8 in Id/Vds curves, J55/J56/K175/K176]
you'd have to use 18 anyway, half the Pd of the 200W Sanken MT200.
[If it's 8 amps (7 for the 100W types), why values higher than 8 in Id/Vds curves, J55/J56/K175/K176]
I think the answer is in the power dissipation/thermal resistance curves. The peak current can be much higher on some parts but not by audio standards. The weakness is driving the large non-linear input capacitance of the big FETs. That can add up to a lot of peak current if you have a lot of FETs in parallel.
Personally I'm not impressed by uber big amps. If amps sound different then smaller amps usually sound better.
Personally I'm not impressed by uber big amps. If amps sound different then smaller amps usually sound better.
In the eighties I designed 5kW-Mono-Blocks with 36 complementary hitachi pairs paralleled.
Supplied by +- 80V, with peak currents upto +-200amps.
Driving reactive load with +-60 phase angle.
I think these devices have been the best for linear audio power amps for all times.
Just my 2c
Supplied by +- 80V, with peak currents upto +-200amps.
Driving reactive load with +-60 phase angle.
I think these devices have been the best for linear audio power amps for all times.
Just my 2c
You should know, Mr Martin.
Laterals are better suited for smaller power amps, better than BJT's, imho.
>>10A/device for a 1ms peak may not be audio standard.
(Still have the hybrid monaurals I posted a link of, Full 80W class A at 2.4A quiescent current, 4 pairs of J50/K135. The N-channel devices of both amps are from the same area of one wafer, same same for the P-channels, cost me more than twice the going rate of the laterals back then. Likely why I now have over a thousand NOS ones, probably an ego problem thing
)
one good simplification :
( for 2sk1058 et. al. )
each device has a 1 Ohm built in resistance
AND !
the temperature coefficient : ) ( I'd use darlingtons that had that coefficient )
( for 2sk1058 et. al. )
each device has a 1 Ohm built in resistance
AND !
the temperature coefficient : ) ( I'd use darlingtons that had that coefficient )
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