So I have a Hiraga, it's over 30 years old and may well have been an original build by Hiraga or created by another for Expolinear speakers - it's branded Expolinear and i was told was used to demo their speakers back in the day.
It sounds very very good, beating my big Cary valve amps in almost every area except soundstage. To fix this id like to try changing some components but as there are so many different schematics out there I have no idea which applies to my amp. So, if I take some pics could someone point me in the right direction?
Adey
It sounds very very good, beating my big Cary valve amps in almost every area except soundstage. To fix this id like to try changing some components but as there are so many different schematics out there I have no idea which applies to my amp. So, if I take some pics could someone point me in the right direction?
Adey
Interesting. Hiraga has designed several amplifiers, you may consult the (elaborate) threads about them at this diyaudio forum.
In order to reflect on your question, the specific schematic of your amplifier would be helpful. Do you have the original schematic? If not, can you please re-engineer the schematic, preferably inclusive the type of components? An existing schematic as can be found on this forum or on internet may help you getting started. The type of output transistors as found in your amplifier can point towards the appropriate design.
BTW, I do not grasp the meaning of the word 'idiot' as used in the heading of your post. If meant as is in 'we are all idiots building and modifying diy-stuff', it is superfluous. Otherwise, Hiraga is all but an idiot.
In order to reflect on your question, the specific schematic of your amplifier would be helpful. Do you have the original schematic? If not, can you please re-engineer the schematic, preferably inclusive the type of components? An existing schematic as can be found on this forum or on internet may help you getting started. The type of output transistors as found in your amplifier can point towards the appropriate design.
BTW, I do not grasp the meaning of the word 'idiot' as used in the heading of your post. If meant as is in 'we are all idiots building and modifying diy-stuff', it is superfluous. Otherwise, Hiraga is all but an idiot.
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Wow... never seen that! The Hiraga 20W Class A I know of is that in the image I posted.
By the way I found this: For sale - General Amp Clear Out, Jean Hiraga, Gate Audio, Yves cochet
They say it is the clone.
By the way I found this: For sale - General Amp Clear Out, Jean Hiraga, Gate Audio, Yves cochet
They say it is the clone.
The PCB looks right, but I've never seen that chassis. I visited the production line of the Lectron amp a few times, and built a couple of my own, but don't know that model you have.
What I don't understand is why you want to change it? It's a wonderful amp, why mess with it? You can buy kits to build from scratch on eBay. Maybe you want to try that and use your power supply? What are your goals?
What I don't understand is why you want to change it? It's a wonderful amp, why mess with it? You can buy kits to build from scratch on eBay. Maybe you want to try that and use your power supply? What are your goals?
It's the simplicity, the well chosen and matched parts, the massive power supply that make it such a good amp.Hello,
A rather easy modification is changing the two 1K8 ohm resistor which are right above the soldering connection of the wires going to the output transistor. I did change them into 2 watt Allen Bradley 2Kohm or even 2K2 ohm. I changed them more than 30 years ago!! It is not the value change that gives the improvement but probably the bigger wattage and/or type of resistor. I did use the Shinko tantal resistors at that time as used in the original design.
A REALLY nice improvement would be replacing the two resistors in the power supply by two chokes like Lundahl LL1694. Look for the value of the resistors calculate how much there is running. Probably the choke will give a little bigger voltage drop but that is ok!
Greetings, Eduard
A rather easy modification is changing the two 1K8 ohm resistor which are right above the soldering connection of the wires going to the output transistor. I did change them into 2 watt Allen Bradley 2Kohm or even 2K2 ohm. I changed them more than 30 years ago!! It is not the value change that gives the improvement but probably the bigger wattage and/or type of resistor. I did use the Shinko tantal resistors at that time as used in the original design.
A REALLY nice improvement would be replacing the two resistors in the power supply by two chokes like Lundahl LL1694. Look for the value of the resistors calculate how much there is running. Probably the choke will give a little bigger voltage drop but that is ok!
Greetings, Eduard
Hello,
I did ask the people in Paris who were selling amps like the Hiraga if i could use a choke that was developped for another design. They said SURE.
Besides the LL1694 there is also the LL2733. It has more mH but also higher serie resistance. I think both Lundahl should be used with their two coils in parallel to reduce DCR.
Hifi collective in the UK has 2k2 AB 2 watt in stock. There could be resistors who could give a bigger improvement but i dont know which one. Maybe the audio note tantal 2 watt or the Mills mra 5. The AB are cheap. If you like the improvement you can decide to try other 2 watt resistors.
BUT i am alomost sure that AB resistors and two LL1694 will give more improvement than 4 audio note resistors.
Greetings, Eduard
I did ask the people in Paris who were selling amps like the Hiraga if i could use a choke that was developped for another design. They said SURE.
Besides the LL1694 there is also the LL2733. It has more mH but also higher serie resistance. I think both Lundahl should be used with their two coils in parallel to reduce DCR.
Hifi collective in the UK has 2k2 AB 2 watt in stock. There could be resistors who could give a bigger improvement but i dont know which one. Maybe the audio note tantal 2 watt or the Mills mra 5. The AB are cheap. If you like the improvement you can decide to try other 2 watt resistors.
BUT i am alomost sure that AB resistors and two LL1694 will give more improvement than 4 audio note resistors.
Greetings, Eduard
Hello,
It seems this thread is about to die soon.
There are not many people who tried Lundahl chokes like the ll1694 or ll2733 in solid state power amplifiers. If there is a choke used it will usually be a Hammond with something like 10 mH.
The original choke i bought in Paris was 200 mH. I also used it in a 20 watt Hiraga built for a friend.
A friend in Vietnam will finish his Nelson Pass amp with LL2733 choke input power supply. Choke input will need much more AC voltage from the transformer to get the right DC voltage for the circuit. So switching to choke input will need another transformer.
Hiraga amp seems to be sensitive to the quality of the power supply. These chokes will have infinite lifetime so i guess it is one of the best investments to make for this amp.
With choke input you will need another transformer and i would switch to 35/40 volt caps for the first cap. Would be wise to install a bleeder to assure a minimum current flow all the time. For the 30 watt Hiraga the cap right after the rectifier is used to close to its rating.
greetings, Eduard
It seems this thread is about to die soon.
There are not many people who tried Lundahl chokes like the ll1694 or ll2733 in solid state power amplifiers. If there is a choke used it will usually be a Hammond with something like 10 mH.
The original choke i bought in Paris was 200 mH. I also used it in a 20 watt Hiraga built for a friend.
A friend in Vietnam will finish his Nelson Pass amp with LL2733 choke input power supply. Choke input will need much more AC voltage from the transformer to get the right DC voltage for the circuit. So switching to choke input will need another transformer.
Hiraga amp seems to be sensitive to the quality of the power supply. These chokes will have infinite lifetime so i guess it is one of the best investments to make for this amp.
With choke input you will need another transformer and i would switch to 35/40 volt caps for the first cap. Would be wise to install a bleeder to assure a minimum current flow all the time. For the 30 watt Hiraga the cap right after the rectifier is used to close to its rating.
greetings, Eduard
Hello,
I tried to get a closer look at your amp. The original one has one cap after the rectifier, then a resisistor and then two final caps. Because there is a + and a - side you will end up with 4 or 6 caps.
The ones i made use 6 caps and a choke instead of the resistor. If there is enough space inside your chassis it is easy to install!!
The original French 20 watt used 6 68000 µF caps. The 30 watt i built used 2 68000µF caps and 4 330000µF caps.
If your caps are rated 40 volts ( i think they are) you could switch to choke input by adding a 40 volt cap on the + and - side . So both sides ( + and -) will have one choke, one cap with bleeder resistor!!, one resistor and then the two final caps.
The new cap can be something like 33000 µF so you can mount it on the inside.
Like i wrote before with choke input you will need a new transformer! Of course you can start by replacing the original resistor by a choke. If you like it you can switch to choke input which will give a bigger improvement.
I have added Lundahl files so you can check if the LL2733 will fit.
Greetings, Eduard
Hello,
Are you talking to me?
I dont have the photos because i build this amp before the breakthrough of internet. But i can draw the circuit on a piece of paper and post a picture of that.
I remember well the discussion on paper and in real life about the right transformer. The French did not like toriodal transformers but preferred double c core or EI core. I remember seeing a dac built by Jean hiraga using R core transformer sold by Selectronic company in France but manufactured in India. Selectronic however did cease to exist.
One big advantage of choke input is that the transformer '' sees '' a much easier load to drive. So does the rectifier!
Greetings, eduard
p.s
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