Hello Daniel,
Nice to see it is all working. The big caps will take some time to completely show their potential. I will keep reading your stories on this special amp which can be regarded as a real solid state classic. Greetings, Eduard. P.s just get used to the sound before you start changing components or adding the power supply chokes.
Nice to see it is all working. The big caps will take some time to completely show their potential. I will keep reading your stories on this special amp which can be regarded as a real solid state classic. Greetings, Eduard. P.s just get used to the sound before you start changing components or adding the power supply chokes.
lt spice and the hiraga
Maybe I should post this on a new threat. I tried to simulate the 20 Watt Hiraga circuit using LT spice (input is a .asc file where the model is set up). Has anybody done this before? Ofcourse, I would think. For some reason or another the simulation underestimates the idle current (the 20 Watter as described in the 1983 article has in reality around 800-1000 mA current, but the model predicts around 200-300. The same applies for the 30 Watt version (higher rail voltage, some resistors changed). I guess the transistor models I use (which are in the program by default) are not that accurate, but on the other hand: 1) in other simulation / amps this is not an issue at all, 2) reality shows that substituting the original transistors with bc550/560 and 2N3055/2955 is without trouble concerning the proper working of the amp (same idle current etc roughly).
Maybe I should post this on a new threat. I tried to simulate the 20 Watt Hiraga circuit using LT spice (input is a .asc file where the model is set up). Has anybody done this before? Ofcourse, I would think. For some reason or another the simulation underestimates the idle current (the 20 Watter as described in the 1983 article has in reality around 800-1000 mA current, but the model predicts around 200-300. The same applies for the 30 Watt version (higher rail voltage, some resistors changed). I guess the transistor models I use (which are in the program by default) are not that accurate, but on the other hand: 1) in other simulation / amps this is not an issue at all, 2) reality shows that substituting the original transistors with bc550/560 and 2N3055/2955 is without trouble concerning the proper working of the amp (same idle current etc roughly).
I have spiced Hiraga 20 W
Using 800 mA. ( no spice simulator can know real components values)
You have to adjust to get 800 mA.
Actually, The level chosen, 0.8 Ampere for max 1.6 A output
is a very good choice. Do not go too much above this !!!!
I was not too impressed with the spice results
But this is probably why it has very good sounds
this SIMPLE but classical Class A push-pull amplifier.
Using 800 mA. ( no spice simulator can know real components values)
You have to adjust to get 800 mA.
Actually, The level chosen, 0.8 Ampere for max 1.6 A output
is a very good choice. Do not go too much above this !!!!
I was not too impressed with the spice results
But this is probably why it has very good sounds
this SIMPLE but classical Class A push-pull amplifier.
spice
Ok, let's see if I get this right. When I adjust the values of the resistors in spice so that the current gets 800 mA then reality of building proofs that the current will be around double of even more (nothing to do with output in class A etcetera, just static standing current). So I don't understand what you mean: Suppose that in reality I want the current to be 800 mA, that's easy enough, just build the circuit as described in 1983. But if I want to predict (without building or trying) the right values using different power supply and zeners I have a problem.
Do I understand correctly that when you do the spice simulation and tweak values to 800 mA on your screen, then in reality this happens to be the case roughly?
Ok, let's see if I get this right. When I adjust the values of the resistors in spice so that the current gets 800 mA then reality of building proofs that the current will be around double of even more (nothing to do with output in class A etcetera, just static standing current). So I don't understand what you mean: Suppose that in reality I want the current to be 800 mA, that's easy enough, just build the circuit as described in 1983. But if I want to predict (without building or trying) the right values using different power supply and zeners I have a problem.
Do I understand correctly that when you do the spice simulation and tweak values to 800 mA on your screen, then in reality this happens to be the case roughly?
Hi R.
It has been quite a few years since I last simulated the Hiraga circuits but, from memory, my findings were similar to yours. The problem is that the models for most transistors (particularly power types) are grossly inaccurate.
I have spent many hours with a simulated 'test rig' generating various parameter curves and then comparing the results with the relevant datasheet and most models differed significantly.
In fact, there was one simulation program that only had six transistor models (low, medium and high power, low and high frequency) and all the individual device numbers were aliased to one of these six. So identical results would be obtained for a BC560, a BC560C or a 2SA970 etc.
With circuits like the Hiraga that rely heavily on specific transistor parameters to determine the output stage current, the simulation predictions will not match reality.
It has been quite a few years since I last simulated the Hiraga circuits but, from memory, my findings were similar to yours. The problem is that the models for most transistors (particularly power types) are grossly inaccurate.
I have spent many hours with a simulated 'test rig' generating various parameter curves and then comparing the results with the relevant datasheet and most models differed significantly.
In fact, there was one simulation program that only had six transistor models (low, medium and high power, low and high frequency) and all the individual device numbers were aliased to one of these six. So identical results would be obtained for a BC560, a BC560C or a 2SA970 etc.
With circuits like the Hiraga that rely heavily on specific transistor parameters to determine the output stage current, the simulation predictions will not match reality.
true
and correct info, Geoff
I did once compare the actual spice model of standard small signal transistors
'BC550C model'
.. probably also the same model as BC547C
was found copied straight off and multiplied
100% identical in a great number of similar transistors
from different Manufacturers
Was both 2Nxxx and MPSxxxx transistors together with some BCxxxx
so results of my simulation did not change one decimal whatever of those I used
!!!! how about this?
are all those transistors really same die as BC547C .. or .....
2SA970 and 2SC2240, those models I use, are different
and have their own (and very good) parameters.
Maybe because I downloaded and imported my models from some website.
Not originally found in my simulator software.
and correct info, Geoff
I did once compare the actual spice model of standard small signal transistors
'BC550C model'
.. probably also the same model as BC547C
was found copied straight off and multiplied
100% identical in a great number of similar transistors
from different Manufacturers
Was both 2Nxxx and MPSxxxx transistors together with some BCxxxx
so results of my simulation did not change one decimal whatever of those I used
!!!! how about this?
are all those transistors really same die as BC547C .. or .....
2SA970 and 2SC2240, those models I use, are different
and have their own (and very good) parameters.
Maybe because I downloaded and imported my models from some website.
Not originally found in my simulator software.
Thanks Geoff (good to see you are still alive and kicking in audio!). This has to be the explanation. You are right, the number of transistors to choose from is very limited and I just pick one. Normally it doesn't matter a lot (Linsley Hood, Sugden, MF A1), but the Hiraga is more sensitive to the parameters because it is all DC-coupled which means many interdependencies in the model.
Hello All,
If you want the sim to operate closer to the real device parameters
perhaps you can use a "default" component value and edit its parameters to mirror the parameters of the real device you wish to simulate.
If anyone has simmed the amp I would be interested to see the results
-Dan
If you want the sim to operate closer to the real device parameters
perhaps you can use a "default" component value and edit its parameters to mirror the parameters of the real device you wish to simulate.
If anyone has simmed the amp I would be interested to see the results
-Dan
the problem is to sim
without having those default components
I know you have the original transistors used by Hiraga.
But this is not some thing many can get.
And some of us will not build Hiraga 20 W.
We see this amplifier more like a good audio amplifier idea.
One idea we would like to explore a bit more using sim without any build.
Now, you ask me, why explore one idea.
If probably not use it, for real.
It is about human nature to investigate all things.
To increase knowledge and understanding.
For some strange reason.
One human quality children are born with.
And some never will forget.
No matter how old we get (I am close to 60).
And so, our lives will be at a constant learning,
as long as our minds will work & function as it should.
Hope for all my few remaining days.
In the short intervall in time, the period we usual call the lifespan of one man.
Lineup - knows human nature well - as being one of those
without having those default components
I know you have the original transistors used by Hiraga.
But this is not some thing many can get.
And some of us will not build Hiraga 20 W.
We see this amplifier more like a good audio amplifier idea.
One idea we would like to explore a bit more using sim without any build.
Now, you ask me, why explore one idea.
If probably not use it, for real.
It is about human nature to investigate all things.
To increase knowledge and understanding.
For some strange reason.
One human quality children are born with.
And some never will forget.
No matter how old we get (I am close to 60).
And so, our lives will be at a constant learning,
as long as our minds will work & function as it should.
Hope for all my few remaining days.
In the short intervall in time, the period we usual call the lifespan of one man.
Lineup - knows human nature well - as being one of those
josh
I tried the Monstre amplifier a while with 19 Volts on the power rails and around 1 Amps idle current. This worked okay and is roughly the setting of the Hiraga 20 Watt amplifier. Technically speaking it seems plausible that they will work in the 20W too. But 1) the Monstre transistors can have less voltage/current/heat so be careful, 2) they have greater bandwidth etc so I don't know about possible HF instability issues.
I tried the Monstre amplifier a while with 19 Volts on the power rails and around 1 Amps idle current. This worked okay and is roughly the setting of the Hiraga 20 Watt amplifier. Technically speaking it seems plausible that they will work in the 20W too. But 1) the Monstre transistors can have less voltage/current/heat so be careful, 2) they have greater bandwidth etc so I don't know about possible HF instability issues.
