Hi Guys
Sajti, the current sources are tied to the wrong end of the 22R emitter resistors. This might skew the results. Should be better with the correct connection. Low-level performance is also important to test, since THD is a ratio and high signal levels can easily be made to look impressive in this manner. Besides, do you run the amp at a full 30W or 80W level all the time?
It is good to see that low-currents through the front end work well as this allows the use of TO-92s and similar, which have a wide range of performance to choose from and are small. My board posted above has a TO-92 diamond.
It is unknown whether there is a resolution below which the distortion spectrum is unimportant. I believe it is best to have the most unobtrusive or balanced spectral response possible.
Have fun
Kevin O'Connor
Sajti, the current sources are tied to the wrong end of the 22R emitter resistors. This might skew the results. Should be better with the correct connection. Low-level performance is also important to test, since THD is a ratio and high signal levels can easily be made to look impressive in this manner. Besides, do you run the amp at a full 30W or 80W level all the time?
It is good to see that low-currents through the front end work well as this allows the use of TO-92s and similar, which have a wide range of performance to choose from and are small. My board posted above has a TO-92 diamond.
It is unknown whether there is a resolution below which the distortion spectrum is unimportant. I believe it is best to have the most unobtrusive or balanced spectral response possible.
Have fun
Kevin O'Connor
Sruth, you have right, I was not careful enough. I have changed the schematic. The results are still impressive 0.00022% with 100W/8ohm. The 5th harmonic is -112dB comparing the +30dB output. The distortion mainly 2nd and 3rd harmonic
This is just a simulation, and it was never build before. BUt the output triplet is well working, and I used it with many other amplifier.
Maybe I will plan the PCB for it tonight, if I have time to do it.
Sajti
This is just a simulation, and it was never build before. BUt the output triplet is well working, and I used it with many other amplifier.
Maybe I will plan the PCB for it tonight, if I have time to do it.
Sajti
Very interesting. Basicaly the same than the Ampliwire 100 from Electrocompaniet - go to post #3 about
http://www.diyaudio.com/forums/newreply.php?do=newreply&p=3227049
but with other kind of stages in front of and behind the interfaces between the amp and buffer sections.
What is to do for convert the push pull output version in a single ended version - to get for an enhanced version from Andrea Ciuffoli's Power Follower e. g. ?? - go to
the Power Folllower
for looking the genuine topology.
The only reason I could find in your posts was that they are capable of being bolted together.
What have I missed?
Hi Guys
It is not simply a matter of preferring one case type to another - although that is a valid basis of choice for many applications - but also picking the right devices that come in that preferred case.
Like many things in audio, the BDs and the TO-126 are "old school". There are nice devices in this line that are very inexpensive. However, if you are willing to look beyond 1970s US and European parts production, you find a world of better parts, newer production techniques, all around better value. Semi prices have fallen to the point that there is no cost justification especially for small builders to choose the cheaper part just because it's cheaper. For pennies more, you get a far better part.
Either package is over-kill for the input section and CSs of certain versions of the LU buffer. However, if you push the supplies and the currents as Lineup likes to do, then you are better off with the larger case if you want reliability. The 2SA/2SCs are colloquially "TO-220Fs" as they are fully epoxy encapsulated. This makes their mounting supremely simple. I've used these drivers and their predecessors since the 1980s. Despite claims to the contrary, their linearity and performance outshines any BD you wish to throw at them. So, for me it saves inventorying many different devices as these fit many apps.
The actual dissipation of the device in a given circuit position is further complicated by ambient temp, particularly if the amp is biased hot, or if airflow within the chassis is limited in any way. You might have a fairly open mechanical design, but then you stick the amp in a wooden cabinet with the other stereo and video gear. Things might cook.
A place where one should always pick the larger case is when selecting mosfets for linear applications. Most mosfets are designed for switching circuits, as that is where their incredible speed can truly be used. Dissipation ratings for a given case size are quite "optimistic". It used to be that the TO-264 was good to about 150W, then 300W - now there are 2k4W devices. But... those parts rated >300W in this case require liquid cooling even for the switching app. If you look at the SOA, they really are weany for DC operation. Same goes with a TO-220 rated for more than 50-75W. It just won't work reliably in a linear app.
Have fun
Kevin O'Connor
It is not simply a matter of preferring one case type to another - although that is a valid basis of choice for many applications - but also picking the right devices that come in that preferred case.
Like many things in audio, the BDs and the TO-126 are "old school". There are nice devices in this line that are very inexpensive. However, if you are willing to look beyond 1970s US and European parts production, you find a world of better parts, newer production techniques, all around better value. Semi prices have fallen to the point that there is no cost justification especially for small builders to choose the cheaper part just because it's cheaper. For pennies more, you get a far better part.
Either package is over-kill for the input section and CSs of certain versions of the LU buffer. However, if you push the supplies and the currents as Lineup likes to do, then you are better off with the larger case if you want reliability. The 2SA/2SCs are colloquially "TO-220Fs" as they are fully epoxy encapsulated. This makes their mounting supremely simple. I've used these drivers and their predecessors since the 1980s. Despite claims to the contrary, their linearity and performance outshines any BD you wish to throw at them. So, for me it saves inventorying many different devices as these fit many apps.
The actual dissipation of the device in a given circuit position is further complicated by ambient temp, particularly if the amp is biased hot, or if airflow within the chassis is limited in any way. You might have a fairly open mechanical design, but then you stick the amp in a wooden cabinet with the other stereo and video gear. Things might cook.
A place where one should always pick the larger case is when selecting mosfets for linear applications. Most mosfets are designed for switching circuits, as that is where their incredible speed can truly be used. Dissipation ratings for a given case size are quite "optimistic". It used to be that the TO-264 was good to about 150W, then 300W - now there are 2k4W devices. But... those parts rated >300W in this case require liquid cooling even for the switching app. If you look at the SOA, they really are weany for DC operation. Same goes with a TO-220 rated for more than 50-75W. It just won't work reliably in a linear app.
Have fun
Kevin O'Connor
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No they dont outperform the BDs, please show proof, I will then show proof otherwise. The bd137-140 series has less than half the Cob of parts like the toshibas. They also are much faster, 150Mhz compared to 100 that toshibas can manage. The important factor is that the toshibas need to be biased at 100ma and higher to be able to even reach 100Mhz wheres the BDs do this at 30ma. Where does one usually bias drivers for class AB at, 100ma and up, I dont think so. Further the BDs display hfe near twice as high as any toshiba.
They are only inferior when it comes to VA and SOA, use two in paralell and till their rated Vceo they easily outperform any toshiba or any other make of driver.
Actually they are, the old philips ones but you could just experiment by yourself and see it in real life, just dont use onsemi BD parts, they are nowhere close to original spec.
Hi Guys
The Philips data books provide Ft info for the BDs where Motorola's does not.
You are free to use my share of BDs in all your amps for "superior" performance. I've never had to bias the 2SA/2SCs any hotter than any other device to have amazing performance, but maybe things work differently in this time zone?
Frankly, I think my hearing must be going because I can't hear anything over 1MHz.
Have fun
Kevin O'Connor
The Philips data books provide Ft info for the BDs where Motorola's does not.
You are free to use my share of BDs in all your amps for "superior" performance. I've never had to bias the 2SA/2SCs any hotter than any other device to have amazing performance, but maybe things work differently in this time zone?
Frankly, I think my hearing must be going because I can't hear anything over 1MHz.
Have fun
Kevin O'Connor
Hi Guys
Ah... germanium. Very leaky. Have to wear a bib when eating them.
Dadod, your circuit is nicely simplified. The same current-source treatment could be used effectively with larger output stages, although the CSs won't provide the slew rate of the local-feedback type CSs - still great performance, though
Have fun
Kevin O'Connor
Ah... germanium. Very leaky. Have to wear a bib when eating them.
Dadod, your circuit is nicely simplified. The same current-source treatment could be used effectively with larger output stages, although the CSs won't provide the slew rate of the local-feedback type CSs - still great performance, though
Have fun
Kevin O'Connor
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