Anyone built this amp? Having problems finding the transistors...
Does the PSU have to be so big, I think it is over 0,5F/ch!
It looks like a very fine amplifier.
http://www.gmweb.btinternet.co.uk/monster31.htm
Does the PSU have to be so big, I think it is over 0,5F/ch!
It looks like a very fine amplifier.
http://www.gmweb.btinternet.co.uk/monster31.htm
It is a Class A amplifier.chrille said:
Do you know how much idle Current it is?
It is also a Current feedback amplifier,(fb goes to emitter of input transistors)
and they are a little more demanding on Power Supply things/disturbance.
In this amplifier it is also not possible to decouple
the pre- and output power supply from eachother.
But you are right. It is a great amplifier!
Only 8 watts.
But those 8 watts will be of very high quality
Like first 8 watts of a 100-200 watts normal class AB amp, maybe.
/halo
Halojoy
This is the reason why monstrous capacitors are needed.
This amplifier can give very superior sound quality, but is now very difficult to build, because of the very hard to find transistors. Substitutes are not possible without audible degradation of the sound quality.
Regards, Pierre Lacombe.
I agree with Nelson.Nelson Pass said:
There are even better substitutes of transistors.
Not to mention low voltages high uF Electrolytic Caps.
And toroid trafos.
Regarding power supply to suit this amplifier,
there is a lot to find in Pass Sites and Forum.
This class A amplifier is a bit like some Pass Amplifiers
when it comes to what is needed in a pure and well filtered supply.
An alternative to big cap bank is
a cap-inductor-cap filter (CLC) that the Pass-builder-guys
sometimes uses and Nelson recommends.
A big selfmade air-inductor is a lot cheaper
then those big high quality electrolytes, like RIFA and those.
The good thing regarding the Caps to this amp is
the low voltage. 25 volts caps are half the price of 50 volts.
/halo
P.Lacombe said:
Here are some suggested replacement transistors
http://www.gmweb.btinternet.co.uk/hiragatrans.htm
substiutes
but that the substitute can take and work well
at the current and the voltage that is in the circuit.
Of course if you have ratings same or higher than the original
it is never any problems.
But if you in a circuit with 24 max voltage,
substitute the original transistor, 45 max volt,
with a transistor with max 30 volt,
it is perfectly okay.
As the circuit only demands 24 volt.
There are other data that can be more important.
Ft= the speed of the transistor MHz
the noise and and the gain, hfe.
---------------------------------------
In Class A amplifier where a lot of current and heat is involved
there is also important how well the transistor
can cool itself down.
This is the data C/W.
It is related to the Max Power data.
It is good if C/W is as low (or lower) than the original
output transistor.
If it is higher you might need a bigger heatsink,
and heatsinks cost more money than a transistor
with good data.
And if C/W is too high there is a limit, where not even
the biggest heatsink will be enough.
---------------------------------------
The circuit sets the demands on the transistor.
The max data sets a limit for, IF transistor can do the job
without breakdown.
And secondly HOW WELL it will do the job.
/halo
The important is not that it is same,RobPhill33 said:
but that the substitute can take and work well
at the current and the voltage that is in the circuit.
Of course if you have ratings same or higher than the original
it is never any problems.
But if you in a circuit with 24 max voltage,
substitute the original transistor, 45 max volt,
with a transistor with max 30 volt,
it is perfectly okay.
As the circuit only demands 24 volt.
There are other data that can be more important.
Ft= the speed of the transistor MHz
the noise and and the gain, hfe.
---------------------------------------
In Class A amplifier where a lot of current and heat is involved
there is also important how well the transistor
can cool itself down.
This is the data C/W.
It is related to the Max Power data.
It is good if C/W is as low (or lower) than the original
output transistor.
If it is higher you might need a bigger heatsink,
and heatsinks cost more money than a transistor
with good data.
And if C/W is too high there is a limit, where not even
the biggest heatsink will be enough.
---------------------------------------
The circuit sets the demands on the transistor.
The max data sets a limit for, IF transistor can do the job
without breakdown.
And secondly HOW WELL it will do the job.
/halo
I'm old enough (unfortunately!) to perfectly remember that famous 8 W pure class A amplifier.
I still keep some original articles published on the magazine "L'Audiophile" around '83-'84.
I also remember that all the transistors were carefully choosen for their sound, not only for specs.
Probably you don't know that the preferred PS was using two large batteries (12 V / 45 A) bypassed by several big caps!
The original schematics came from a prototype made by a famous Japanese company (could be Accuphase, but I'm not 100% sure) and never launched on the market. The idea was to develop a SS amp that could compete with the famous tube WE 300 B in SE (that's why the output power was 8 W)
J.Hiraga simply "imported" that idea in Europe and wrote some articles introducing few mods and a beefy PS with car batteries and huge caps. A "C" core trafo was used to recharge them after few hrs.
P.S. Sorry, just read again the first article: the manufacuter that introduced the prototype was Stax and not Accuphase
I still keep some original articles published on the magazine "L'Audiophile" around '83-'84.
I also remember that all the transistors were carefully choosen for their sound, not only for specs.
Probably you don't know that the preferred PS was using two large batteries (12 V / 45 A) bypassed by several big caps!
The original schematics came from a prototype made by a famous Japanese company (could be Accuphase, but I'm not 100% sure) and never launched on the market. The idea was to develop a SS amp that could compete with the famous tube WE 300 B in SE (that's why the output power was 8 W)
J.Hiraga simply "imported" that idea in Europe and wrote some articles introducing few mods and a beefy PS with car batteries and huge caps. A "C" core trafo was used to recharge them after few hrs.
P.S. Sorry, just read again the first article: the manufacuter that introduced the prototype was Stax and not Accuphase
DISCLAIMER THIS IS MY HONEST OPINION THAT HAS ONLY TO DO WITH THE FACT I BUILT ALL THE AMPS I AM GOING TO TALK ABOUT.
I built both the Hiraga amps (Monstre and le classeA)and the AX and while the Hiraga do sound very nice the AX simply blow them out of the water.
I don't know if it's because of the balanced AX vs SE hiraga, the different trannies I used for the hiraga, the SANKEN 2sc2922/pnp? pair that are said to be the among the best bjt out there, the regulated PS of the hiraga vs the 1F pi filter in the AX.
I believe I used better components than were used on the original Hiraga, and I got a little bit harder time to get the 0 DC offset. As of right now it starts at 120 mV and goes to ~0 during the course of 1/2 hr.
I am just gonna throw it out there, you make whatever you want out of it.
Frank,
Sorry, I could not resist. There seems to be a lack of humor in the forum these days.
I built the Monster a few years ago (many) and it was a great sounding amp, being a current feedack device we can convert it into a x-amp. ( See other thread) Maybe we could convince you to build one.
Jam
Sorry, I could not resist. There seems to be a lack of humor in the forum these days.
I built the Monster a few years ago (many) and it was a great sounding amp, being a current feedack device we can convert it into a x-amp. ( See other thread) Maybe we could convince you to build one.
Jam
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