Salas, you walk on shaky ground. You see, SOME people do actually design components for 'effect' but Charles and I don't, and I would not purposely work with someone who did.
This would be the equivalent of defect in an auto so that it would not perform properly.
I have spent my lifetime trying to make better audio designs, and I take it very seriously.
This would be the equivalent of defect in an auto so that it would not perform properly.
I have spent my lifetime trying to make better audio designs, and I take it very seriously.
Hi Jacco,
You mean there are people that the datasheets very serious, not just as a rough guide to what things may be?
Whatever next?
Next you will tell me that there are people who take chips that have good looking Datasheets, apply them based on the notes in the datasheet and think they have "designed" "world class" Audio Gear!?
Pull the other one please...
The Late and Great Bob Pease had one crucial thing to say about manufacturers data sheets (including one supposes those by Nat Semi - though they often tell more than most): "They never tell what is really important about the part."
Ciao T
You mean there are people that the datasheets very serious, not just as a rough guide to what things may be?
Whatever next?
Next you will tell me that there are people who take chips that have good looking Datasheets, apply them based on the notes in the datasheet and think they have "designed" "world class" Audio Gear!?
Pull the other one please...
The Late and Great Bob Pease had one crucial thing to say about manufacturers data sheets (including one supposes those by Nat Semi - though they often tell more than most): "They never tell what is really important about the part."
Ciao T
Goedemorgen Mynheer VerMeulen,
I actually had you more down as Zdeněk Miler's Krtek (to stay in Prague), Schwejk is so early last Millenium...
But I must admit, the way things go hear do at times remind me of "Die Feuerzangenbowle".
Ciao T
I actually had you more down as Zdeněk Miler's Krtek (to stay in Prague), Schwejk is so early last Millenium...
But I must admit, the way things go hear do at times remind me of "Die Feuerzangenbowle".
Ciao T
Which brings up the issue of data sheets. I have found that for example the ON semi data sheets on their PNP audio devices to be accurate to slightly optimistic but the NPN data to be low on Ft and Gain in particular. So where the devices are shown to be typically complimentary, you would have to sort to get the "bad" NPNs to really match.
The technique I have looked at is to mount the PNP devices on a separate heatsink and add a power resistor with temperature monitoring on both heatsinks to keep the PNPs warm and happy! I have done this with input pairs. Turns out there is a sweet spot in operating temperature for input devices. The difference can be used for a DC servo.
The technique I have looked at is to mount the PNP devices on a separate heatsink and add a power resistor with temperature monitoring on both heatsinks to keep the PNPs warm and happy! I have done this with input pairs. Turns out there is a sweet spot in operating temperature for input devices. The difference can be used for a DC servo.
I think that I understood what Salas was saying. However, it tends to promote a stereotype of audio design that is not usually correct. That we design for 'effect' rather than quality. I have dealt with this device difference, and still do today. You don't win listening contests with such parts. I measured the difference, as well, once, about 10 years ago, and had Parasound replace certain parts in our amps.
The 12AT7 has fairly high 2nd harmonic, but a nicely falling waterfall harmonic plot in general. Third harmonic is fairly low, and since the second is mostly canceled in the OPT the overall result can be quite good. Other advantages include high transconductance, (relatively speaking) low rp and relatively high current operation for good bandwidth particularly when driving triode connected beam tubes or pentodes. It is a very reasonable design choice in this application. (I do prefer the 6SN7, 6CG7/6FQ7 or ECC99 for phase splitter duty, but since I no longer really design PP tube amps this is probably moot.)
Remarkably though, when talking Lateral versus Vertical, opposite sides seem to meet.
Both Mr Hansen and Mr Curl, as Mr Stuart and Mr Popa, seem to prefer Lateral over Vertical when talking MOSFET shop.
This sums it up rather nice :
(wish to see a thousand Lateral power devices before me drop down the hole again ?)
Both Mr Hansen and Mr Curl, as Mr Stuart and Mr Popa, seem to prefer Lateral over Vertical when talking MOSFET shop.
This sums it up rather nice :
20-25 years ago, Laterals were the De Facto parts, and Vertical MOSFETs were oddball switching parts for high NFB amps as a lower cost alternative.
(wish to see a thousand Lateral power devices before me drop down the hole again ?)
Yeah, I saw you wearing your "VERTICAL MOSFETS DO IT STANDING UP" t-shirt at the show.
se
I've *finally* made it through all bazillion posts of both parts One and Deax, and would like to thank everyone for a very interesting master class that seems to still have some real life in it. Hoped to comment on two things left unresolved in earlier parts:
First, with respect to wet-playing of vinyl records, folks whose opinions I trust, like Scott Dorsey for example, believe that the noise in later dry play is caused by subsurface changes to the vinyl itself. Normal dry play operates at tremendous temperature and pressure, maybe up into the several hundred degrees F, with deformation and resolidifying. Wet-play is thought to interfere with this high temperature process. Stuff at this tiny level is borderline PFM anyway.
Second, with respect to the audio file sent to and from an audio workstation, any DAW made in the last ten years at least will automagically include proper dither for any reduction in word length. The importation of a 16 or 24 bit file to a 64 bit workspace is lossless (padded with zeros), but the truncation back to 16 or 24 bits is *always* dithered. Therefore the file will be changed slightly (by addition of the dither) and a very careful listener will be able to tell the difference.
Thanks again to all, especially Mr. Curl for keeping the class alive and so worthwhile.
First, with respect to wet-playing of vinyl records, folks whose opinions I trust, like Scott Dorsey for example, believe that the noise in later dry play is caused by subsurface changes to the vinyl itself. Normal dry play operates at tremendous temperature and pressure, maybe up into the several hundred degrees F, with deformation and resolidifying. Wet-play is thought to interfere with this high temperature process. Stuff at this tiny level is borderline PFM anyway.
Second, with respect to the audio file sent to and from an audio workstation, any DAW made in the last ten years at least will automagically include proper dither for any reduction in word length. The importation of a 16 or 24 bit file to a 64 bit workspace is lossless (padded with zeros), but the truncation back to 16 or 24 bits is *always* dithered. Therefore the file will be changed slightly (by addition of the dither) and a very careful listener will be able to tell the difference.
Thanks again to all, especially Mr. Curl for keeping the class alive and so worthwhile.
Chris, I am glad that you went back to the beginning. This is where we were the most successful in conveying circuit designs relating to the Blowtorch and similar designs. As I later tried to talk about 'more subtle' factors, rather than topology, shielding, etc, more and more confrontation and interference set in. Now, the thread has examples of real information, mixed with 'off' comments tending to dilute or confuse the thread. I call this P'ing on the thread '-) Unfortunately, I have no control over what is said or what stays.
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