I can design phonostages and preamps of high quality but i do not have such a good relationship to poweramps.
The first amp i tried to build when i was 13 years old was a desaster.
I had made the classic mistake of reversing the Elcaps in the PSU.
Bang, and it was gone and all the hard money that i had saved.
Since then i am still a bit traumatised.
I then made a deal with the univers and limited myself to 1A maximum and plus-minus 24V.
The first amp i tried to build when i was 13 years old was a desaster.
I had made the classic mistake of reversing the Elcaps in the PSU.
Bang, and it was gone and all the hard money that i had saved.
Since then i am still a bit traumatised.
I then made a deal with the univers and limited myself to 1A maximum and plus-minus 24V.
Build a simpler chipamp, to get confidence in your POWER building.
Learn how the Mains Bulb Tester is your friend, that is always looking over your shoulder to protect from disastrous mistakes.
Try deliberately shorting the secondary of the transformer to see what happens to the Bulb filament.
Try deliberately miswiring the dual primary, or dual secondary and see what the bulb shows.
Try adding on an ENORMOUS smoothing cap bank. See what the Bulb has to show.
Learn how the Mains Bulb Tester is your friend, that is always looking over your shoulder to protect from disastrous mistakes.
Try deliberately shorting the secondary of the transformer to see what happens to the Bulb filament.
Try deliberately miswiring the dual primary, or dual secondary and see what the bulb shows.
Try adding on an ENORMOUS smoothing cap bank. See what the Bulb has to show.
I got my kick from an 100uF cap of an old surplus shortwave transmitter charged to 450V that discharged from my left hand all over to my right hand. This stopped my endeavers with tube amps for a lifetime and I built transistor amps since then.
Most failures occured with bjt amps, when high-frequency oscillations grilled the output devices. With latFETs appearing in the eighties, a new era began. These were nearly indestructable, gave wide bandwidth and no biasing problems at all. These were the best devices for linear amps of all times imho.
So if you go for linear amps, go for latFETs.
Just my 2c
Most failures occured with bjt amps, when high-frequency oscillations grilled the output devices. With latFETs appearing in the eighties, a new era began. These were nearly indestructable, gave wide bandwidth and no biasing problems at all. These were the best devices for linear amps of all times imho.
So if you go for linear amps, go for latFETs.
Just my 2c
I use 10ohm 10watt safety resistors in between the PSU and amp during startup for first time and look at voltage across to check current. This has saved me countless times form blowing up output stages. It's amazing how often we have mistakes even though we do this all the time. A mains bulb will do the same thing and glow as an indication of over current (or something is amiss). I never startup an amp for first time without one.
I have experimented with 10r 600mW as "fuses" or current limiters/voltage droppers for power amplifiers.
I don't think they do much for protecting circuits from a wiring or component insertion mistake.
They fizzle for a while until they finally go open circuit. During that first moment of overcurrent the semiconductors are already destroyed/damaged.
Properly rated secondary fuses (after the mains smoothing capacitors) will blow much more quickly than overheated resistors.
But even fuses cannot protect semiconductors. They rupture too slowly.
Whereas the bulb limiter in a Mains Bulb Tester detects the overload DURING the start up and goes to GLOWING, or BRIGHT.
The partially lit bulb is a good indicator, but the BIG ADVANTAGE is that it reduces the voltage available at the transformer primary.
If the transformer primary were to see only 20Vac (dimmly glowing bulb) instead of 230Vac, then the maximum secondary voltage of a typical 35-0-35Vac transformer in a 100W amplifier would be down to just 4.3Vac (total input power <¼W) and the rectified voltage is down from 50Vdc to about 5Vdc.
The potential for damage inside the amplifier is massively reduced. But it gets better. If the miswired circuit tries to draw substantial current the bulb goes straight to bright and the output of that big transformer never rises much above 2Vdc. Some of the semiconductors don't even get a chance to turn on.
I don't think they do much for protecting circuits from a wiring or component insertion mistake.
They fizzle for a while until they finally go open circuit. During that first moment of overcurrent the semiconductors are already destroyed/damaged.
Properly rated secondary fuses (after the mains smoothing capacitors) will blow much more quickly than overheated resistors.
But even fuses cannot protect semiconductors. They rupture too slowly.
Whereas the bulb limiter in a Mains Bulb Tester detects the overload DURING the start up and goes to GLOWING, or BRIGHT.
The partially lit bulb is a good indicator, but the BIG ADVANTAGE is that it reduces the voltage available at the transformer primary.
If the transformer primary were to see only 20Vac (dimmly glowing bulb) instead of 230Vac, then the maximum secondary voltage of a typical 35-0-35Vac transformer in a 100W amplifier would be down to just 4.3Vac (total input power <¼W) and the rectified voltage is down from 50Vdc to about 5Vdc.
The potential for damage inside the amplifier is massively reduced. But it gets better. If the miswired circuit tries to draw substantial current the bulb goes straight to bright and the output of that big transformer never rises much above 2Vdc. Some of the semiconductors don't even get a chance to turn on.
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At this moment i have 3 candidates and i have build parts.
One is this :http://www.andiha.no/articles/audio/nostalgia/nostalgia.pdf
One is this :http://www.andiha.no/articles/audio/nostalgia/nostalgia.pdf
I build this complete but i could not make it work without noise :
https://linearaudio.net/article-detail/2224
Also my " expert " friends could not make my build work.
I had great hopes for this because it is so simple.
https://linearaudio.net/article-detail/2224
Also my " expert " friends could not make my build work.
I had great hopes for this because it is so simple.
The third amp i am building is this :
http://www.diyaudio.com/forums/solid-state/236056-axl-amp.html
Reasons are : i have a stash of the power mosfets
it has enough power to drive my high efficiency speaker project
i like the circuit, it is of cause not brand new but with refinement and it is simple
as far as i can see it has simple miller compensation and here comes the titel of this thread : can it be improved by TMC or other more complex compensations ?
http://www.diyaudio.com/forums/solid-state/236056-axl-amp.html
Reasons are : i have a stash of the power mosfets
it has enough power to drive my high efficiency speaker project
i like the circuit, it is of cause not brand new but with refinement and it is simple
as far as i can see it has simple miller compensation and here comes the titel of this thread : can it be improved by TMC or other more complex compensations ?
That s a good design overall, TMC can decrease high frequency residuals but probably that H2/H3 will be the most proeminent and TMC wont reduce those two components since they are basicaly function of the exact design, on this subject i would use other transistors than the BFs for the VAS.
The class A USSA series by Fab, sound superb and very silencious.
My amplilier:
http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-463.html#post4696547
pinnocchio amplifier:
http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-467.html#post4737062
http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-467.html#post4737245
My amplilier:
http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-463.html#post4696547
pinnocchio amplifier:
http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-467.html#post4737062
http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-467.html#post4737245
You should try some of the simple amp projects by Apex Audio. Low parts count and easy to make. They sound fantastic too. His amp naming convention ends in the number of active components (transistors). So stay below 10 if you want a simple amp. FX8 is real easy to make.
Look in the directory in post 1 for amp ideas. My favorite is the FH9 which uses low cost IRFP power MOSFETs for output.
http://www.diyaudio.com/forums/solid-state/292226-directory-apex-audio-amplifiers.html
Look in the directory in post 1 for amp ideas. My favorite is the FH9 which uses low cost IRFP power MOSFETs for output.
http://www.diyaudio.com/forums/solid-state/292226-directory-apex-audio-amplifiers.html
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