Hello Michael,
Slow down
To have it playing you must have the outputs connected up. Yes ?
Read carefully,
Measuring the voltages across R17 and 22 (without the outputs connected) was just a way of checking that all was working O.K.
Did you move those 270 ohm gate resistors up to the legs on the FET's by the way. Good !
With the FET's connected and the pot set back to zero ohms is the output at zero volts DC. Do not connect any speaker while doing this and have nothing connected to the input as well. Post the reading I am interested in what it is
The pot is used to set the current in the output stage -- not voltage-- and the easiest way to set this is to measure the voltage across one of the 0.22 ohm resistors that go to the FET's.
You need to turn the pot to give around 22 millivolts across either resistor, it does not matter which you use. That will give a current of 100ma - dont worry if it seems to alter as the FET'S warm up -- just get it somewhere near.
Let me know how you get on.
Slow down
To have it playing you must have the outputs connected up. Yes ? Read carefully,
Measuring the voltages across R17 and 22 (without the outputs connected) was just a way of checking that all was working O.K.
Did you move those 270 ohm gate resistors up to the legs on the FET's by the way. Good !
With the FET's connected and the pot set back to zero ohms is the output at zero volts DC. Do not connect any speaker while doing this and have nothing connected to the input as well. Post the reading I am interested in what it is
The pot is used to set the current in the output stage -- not voltage-- and the easiest way to set this is to measure the voltage across one of the 0.22 ohm resistors that go to the FET's.
You need to turn the pot to give around 22 millivolts across either resistor, it does not matter which you use. That will give a current of 100ma - dont worry if it seems to alter as the FET'S warm up -- just get it somewhere near.
Let me know how you get on.
hi mooly,
As you have seen on the picture, it was only for showing that it is assembled. Actually I had changed the cables into very short and all are separated. I had to change where ever as it’s require. it’s operate quite cold, not really gets hot. I don't know why you all worry about vro-board. I even made 500w RMS used only vroboard, microchip with LCD and it is operating very, very well. I made for my uncle with two pair of 2sc5200/2sa1943 sumsym amp using 70v and he is using almost three months now without having any problem. That was also on vr-board but well constructed. Until now he is very pleased with that amp. I even got surprise the sound quality coming out from that amp, very clean.
I never use only vro board. I use some places thick copper plate to have higher amp where ever need to use.
Mooly actually i need to do more and check more. I just made it just try to get the sound first then later I will tune more btr for performance. This is the way I do all time.
Thanks for your help. Sound will be more btr when I will use proper circuit and power supply.
Great amp, very nice….
Best regards,
michael
As you have seen on the picture, it was only for showing that it is assembled. Actually I had changed the cables into very short and all are separated. I had to change where ever as it’s require. it’s operate quite cold, not really gets hot. I don't know why you all worry about vro-board. I even made 500w RMS used only vroboard, microchip with LCD and it is operating very, very well. I made for my uncle with two pair of 2sc5200/2sa1943 sumsym amp using 70v and he is using almost three months now without having any problem. That was also on vr-board but well constructed. Until now he is very pleased with that amp. I even got surprise the sound quality coming out from that amp, very clean.
I never use only vro board. I use some places thick copper plate to have higher amp where ever need to use.
Mooly actually i need to do more and check more. I just made it just try to get the sound first then later I will tune more btr for performance. This is the way I do all time.
Thanks for your help. Sound will be more btr when I will use proper circuit and power supply.
Great amp, very nice….
Best regards,
michael
hi mooly,
today i have tuned even more btr then last time. it will takes time to do. now even more nice music sound can produce. the vocal still not get sweet. now i am operating on 36vdc. heat is not get worst. quite stable now. bass is not very deep. anyway over all very nice, very musical..
many thanks for help.
best regards
michael
today i have tuned even more btr then last time. it will takes time to do. now even more nice music sound can produce. the vocal still not get sweet. now i am operating on 36vdc. heat is not get worst. quite stable now. bass is not very deep. anyway over all very nice, very musical..
many thanks for help.
best regards
michael
Hello Michael,
You still having fun Do make sure you do as per the previous post, if you have not got the 22 millivolts across the 0.1 ohms there will be crossover distortion.
What I did not show on the circuit was a 10 ohm 2 watt across the output coil. It should really be present but may not make any audible difference.
Have you grounded it all properly, keeping the input and PSU ground "separate".
You still having fun
Do make sure you do as per the previous post, if you have not got the 22 millivolts across the 0.1 ohms there will be crossover distortion. What I did not show on the circuit was a 10 ohm 2 watt across the output coil. It should really be present but may not make any audible difference.
Have you grounded it all properly, keeping the input and PSU ground "separate".
Hello Michael,
Listen carefully ,
1. Adjust R8 (The pot) for 22 millivolts across R23 with no load attached and with no input signal.
2. Try adding a 10 ohm 2 watt (or 1 watt) carbon or metal film resistor across L1 the coil at the output.
Have you built just one channel or two ?
Nobody else got one going yet.
Listen carefully
,1. Adjust R8 (The pot) for 22 millivolts across R23 with no load attached and with no input signal.
2. Try adding a 10 ohm 2 watt (or 1 watt) carbon or metal film resistor across L1 the coil at the output.
Have you built just one channel or two ?
Nobody else got one going yet.
Hi mooly,
1. Adjust R8 (The pot) for 22 millivolts across R23 with no load attached and with no input signal.
2. Try adding a 10 ohm 2 watt (or 1 watt) carbon or metal film resistor across L1 the coil at the output.
i understand this for adjust bias level at R23....to 22millv....ok i will do that....
i already done L1 coil got one resister that is 0.22ohms 3W as you shown. should i replace it with 10ohms 2w?
i just build one chanel.....i will build another one later on until it is working fine. then just follow same. i am still testing, how its operate. until now there is no unusual sound heat i have found. all looks quite well. i think it is quite fine working...its not rough at all.
thanks for advice.
1. Adjust R8 (The pot) for 22 millivolts across R23 with no load attached and with no input signal.
2. Try adding a 10 ohm 2 watt (or 1 watt) carbon or metal film resistor across L1 the coil at the output.
i understand this for adjust bias level at R23....to 22millv....ok i will do that....
i already done L1 coil got one resister that is 0.22ohms 3W as you shown. should i replace it with 10ohms 2w?
i just build one chanel.....i will build another one later on until it is working fine. then just follow same. i am still testing, how its operate. until now there is no unusual sound heat i have found. all looks quite well. i think it is quite fine working...its not rough at all.
thanks for advice.
hi mooly,
ok....just send you an email about ampire meter.
i really need one circuit for analog ampire panel meter. i have one panel meter it is analog showing 0 to 10ampire. i need a circuit for it to check my power supply for various transformer dc voltage ampire.
pls help me to make this.
thank you.
ok....just send you an email about ampire meter.
i really need one circuit for analog ampire panel meter. i have one panel meter it is analog showing 0 to 10ampire. i need a circuit for it to check my power supply for various transformer dc voltage ampire.
pls help me to make this.
thank you.
KLe,
your pondering is reasonable. Many years ago a friend of mine had a British style single ended input amp, despite many impurities and low quality parts the sound was kinda pleasant and I just could not understand why. It took a long while to find out due to extremely sluggish thinking but enlightening spiritual exercises expand our consciousness and enhance our ability to perceive clearly the inner nature of reality around us. There is no doubt in my mind that this amp is as musical as Mooly says, however, the transcendental guru`s penetrating insightfullness cannot pass by unnoticed, stating: everything can get better. Reassuringly, later on in chapter twelve, indicating nearly infinite wisdom, we also find: all problems have solutions.
Now, the bothering problem with the bias current in the drivers still remains, leaving them without a chance when encountering those huge input capacitances. Moreover, something deep inside tells me that output stages should not have voltage gain...
your pondering is reasonable. Many years ago a friend of mine had a British style single ended input amp, despite many impurities and low quality parts the sound was kinda pleasant and I just could not understand why. It took a long while to find out due to extremely sluggish thinking but enlightening spiritual exercises expand our consciousness and enhance our ability to perceive clearly the inner nature of reality around us. There is no doubt in my mind that this amp is as musical as Mooly says, however, the transcendental guru`s penetrating insightfullness cannot pass by unnoticed, stating: everything can get better. Reassuringly, later on in chapter twelve, indicating nearly infinite wisdom, we also find: all problems have solutions.
Now, the bothering problem with the bias current in the drivers still remains, leaving them without a chance when encountering those huge input capacitances. Moreover, something deep inside tells me that output stages should not have voltage gain...