the amplifier is -3dB @ approx 160kHz.
this is due to the input filter.
without the filter its response extends to ~1MHz. (tapering off)
however the relatively large supply capacitance is only bypassed with 2.2uF and 0.1uF on the busbar and the PCB respectively.
I think I could improve the >10kHz sq. wave response by some improvements in this area.
Thanks for the nice comments lineup - It definately sounds clean
your -3dB estimate was pretty close
Salas I agree with you in regard to the 10kHz square wave.
I will make some adjustments and re measure with a DSO which has higher resolution than the CRO i used.
-Dan
this is due to the input filter.
without the filter its response extends to ~1MHz. (tapering off)
however the relatively large supply capacitance is only bypassed with 2.2uF and 0.1uF on the busbar and the PCB respectively.
I think I could improve the >10kHz sq. wave response by some improvements in this area.
Thanks for the nice comments lineup - It definately sounds clean
your -3dB estimate was pretty close
Salas I agree with you in regard to the 10kHz square wave.
I will make some adjustments and re measure with a DSO which has higher resolution than the CRO i used.
-Dan
ok people,
here is some better quality square wave results:
sadly i shorted the outputs of one channel after testing with a test lead.... so i have to replace the output stage *&%$ !!!!!
hopefully only the output pair 2SC5200/2SA1943 is gone not the "vintage" transistors in the driver stage.
-Dan
here is some better quality square wave results:
sadly i shorted the outputs of one channel after testing with a test lead.... so i have to replace the output stage *&%$ !!!!!
hopefully only the output pair 2SC5200/2SA1943 is gone not the "vintage" transistors in the driver stage.
-Dan
Attachments
Working pair of Le Monstre free to a good home.
If anyone wants these stuffed, and tested boards; send an address. I still have the 10 volt, 250 va power transformer, 6 Jensen 47,000 ufd 25 volt four pole caps, and four chokes to make it sing. None is usable in this next amp.
George
I needed my chassis for another amplifier, so my KK boards stuffed with original matched transistors and AB carbon comp resistors were pulled. Used these with 15 ohm, 1oo dB efficient speakers, they had plenty of power. But today there are 88 dB ,6 ohm and use at least 50 watts to drive.bluevas said:
If anyone wants these stuffed, and tested boards; send an address. I still have the 10 volt, 250 va power transformer, 6 Jensen 47,000 ufd 25 volt four pole caps, and four chokes to make it sing. None is usable in this next amp.
George
Balanced Hiraga???
Hello
I would like to ask some help with my Hiraga Class A amplifier .
The amplifier works well , I like really the sound , now I increase the power supp voltage +/-36V with 2A bias . It is about 50W the power .I really I don't want to use bridged mode to get the balanced verision input .
My question is it possible to used in a balanced mode .
Now in all my system I use balanced cables , balanced preamp ,I know the Hiraga does not need a preamp but it would be easier to connect to the preamp everything than buy to all my amplifiers high quality poti.
If is possible to be done would you please someone help me to modify the attached schematic .
Would you please somebody give me some idea .
Thank You very much .
Hello
I would like to ask some help with my Hiraga Class A amplifier .
The amplifier works well , I like really the sound , now I increase the power supp voltage +/-36V with 2A bias . It is about 50W the power .I really I don't want to use bridged mode to get the balanced verision input .
My question is it possible to used in a balanced mode .
Now in all my system I use balanced cables , balanced preamp ,I know the Hiraga does not need a preamp but it would be easier to connect to the preamp everything than buy to all my amplifiers high quality poti.
If is possible to be done would you please someone help me to modify the attached schematic .
Would you please somebody give me some idea .
Thank You very much .
Attachments
Al the info , schematic ,PC board layout
Hello
I post again all the information about my Hiraga , I used these PC board layout and these schematic .
I don't know if is possible to connect in a balanced mode with out modifying all the schematic .If not I have to go to used in bridged mode but I have to lower my power supp voltage which now +/-36V .
I really would like to used in a balanced mode with out bridging because I have one pair Scan Speak 4Ohms speakers to .
Sometimes I use to use that to .
Another speakers are 8 ohms so with that even the bridged mode would be OK .
My question do it possible to used in a balanced mode with out bridge connected ??
If yes would you be so kind please help me with .I really don't want to spend another $200 for a new transformer .
Right now I have a Plitron 1KVA power transformer in my amp .To lower the voltage I would have to purchase a new transformer in case only possibility the bridge mode far balanced input .
Thanks for the help for all of you !!!
http://www.mohm.ru/index.php/artcls/42-amps/58-hiraga
Greetings
Hello
I post again all the information about my Hiraga , I used these PC board layout and these schematic .
I don't know if is possible to connect in a balanced mode with out modifying all the schematic .If not I have to go to used in bridged mode but I have to lower my power supp voltage which now +/-36V .
I really would like to used in a balanced mode with out bridging because I have one pair Scan Speak 4Ohms speakers to .
Sometimes I use to use that to .
Another speakers are 8 ohms so with that even the bridged mode would be OK .
My question do it possible to used in a balanced mode with out bridge connected ??
If yes would you be so kind please help me with .I really don't want to spend another $200 for a new transformer .
Right now I have a Plitron 1KVA power transformer in my amp .To lower the voltage I would have to purchase a new transformer in case only possibility the bridge mode far balanced input .
Thanks for the help for all of you !!!
http://www.mohm.ru/index.php/artcls/42-amps/58-hiraga
Greetings
what i mean is seperate the base of the 2SA872A and the 2SC1775A input pair and feed direct balanced in. you will need to put the hf filter (680ohm series connection with 33k and 68p in parallel to ground for each transistor base)...... this is just a theory i have not tried it so..... if you want to maybe see how it goes using a dummy load resistor and low bias on the amp.
PS i got my Le class A working again and i now have approx 35V rails, I am running approx 0.8A bias
-Dan
PS i got my Le class A working again and i now have approx 35V rails, I am running approx 0.8A bias
-Dan
Hello Danieljw
Why you run your amp so low bias? That is max 20W in Class A or less .
I want to use the same power size supp. like you but around 2A bias . I want at least 35W in Class A .I know we can not double the power transistor because it use Darlington circuit.
The new ON semi MJL4XXX power transistor can take higher bias . I don't know about Toshiba what you using if it can take higher bias .
My heat sink more than double than yours .
I purchased a OPA that will help me so I can connect to the Aleph1.7 preamp which is balanced .
More info from the OPA what I will use
http://www.thatcorp.com/datashts/1200data.pdf
I think I will not modify the amp I just put these OPA to the front of the amp so I can use it in balanced mode with preamp ,DAC etc.
I do not have the knowledge to modify the amp input so these would be the easiest mode to do the amp to receive balanced signal .
Only possibility to use these OPA .
The best solution it would be to me to trade my 1KVA 30V transformer to lower voltage like 20V (but who need these transformer and same time he has 1KVA 20-0-20V transformer to trade) and put together two more PC board and run it in bridged mode and Balanced input .
To buy a new power transformer more than ($200)from Plitron that to much investment to me now.The truth is the transformer is brand new ,I never powered up yet , I purchased to the Krell KSA clone but I think the Hiraga better choise . With these high voltage transformer to much heat to take care ..
Thanks any way for your advise .
Greetings
Why you run your amp so low bias? That is max 20W in Class A or less .
I want to use the same power size supp. like you but around 2A bias . I want at least 35W in Class A .I know we can not double the power transistor because it use Darlington circuit.
The new ON semi MJL4XXX power transistor can take higher bias . I don't know about Toshiba what you using if it can take higher bias .
My heat sink more than double than yours .
I purchased a OPA that will help me so I can connect to the Aleph1.7 preamp which is balanced .
More info from the OPA what I will use
http://www.thatcorp.com/datashts/1200data.pdf
I think I will not modify the amp I just put these OPA to the front of the amp so I can use it in balanced mode with preamp ,DAC etc.
I do not have the knowledge to modify the amp input so these would be the easiest mode to do the amp to receive balanced signal .
Only possibility to use these OPA .
The best solution it would be to me to trade my 1KVA 30V transformer to lower voltage like 20V (but who need these transformer and same time he has 1KVA 20-0-20V transformer to trade) and put together two more PC board and run it in bridged mode and Balanced input .
To buy a new power transformer more than ($200)from Plitron that to much investment to me now.The truth is the transformer is brand new ,I never powered up yet , I purchased to the Krell KSA clone but I think the Hiraga better choise . With these high voltage transformer to much heat to take care ..
Thanks any way for your advise .
Greetings
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