Yes..i was distant from computers..i could not track forum
Your adjustment steps are fine Nordic..also the "special reduced current biasing", to find 50 miliamps is interesting too.
The off set multimeter will be there, connected into the output line, reading DC milivolts, only during those adjustments.... all multimeters must be removed, also the protective rail resistances must be removed after you finish bias and off set adjustment.
Remember to remove the input short you have made in advance to play the amplifier.
The standard biasing is 800 to 1100 milivolts measured over 10 ohms resistance.....but your heatsinks are not so enormous as we have dreamed.... a smaller current, when iddle, can be helpfull to maintain your temperature stable.
Are you using bias resistances?...or using diodes or VBE multiplier.
Before power the amplifier, i suppose you have measured resistance from plus to ground...from negative rail to ground...from positive to negative....and all those measurements made once more, but this time with ohmeter probe points inverted in polarity referenced the first measurements made. All
reading must be high...something over 30K....this will show you that no short is present into the board construction.
Before you remove your protective pillow (ahahahah) check for possible electrolitic condenser polarity inversion...and also check once more if they are 35 volts or much more related working voltage.
Beeing carefull this way...for sure you will not have surprises...well...are you sure the positive wire is really positive?
hehe....i happens dear Nordic....more often than you can imagine.
regards,
Carlos
.......................................................................................................
Greg
The standard biasing procedure, published in our home page, is correct.
The small reduction was "arranged" as i could see Nordic draws about the amplifier case, the enclosure...depending the way he will arrange the heatsinks..if fins in vertical or horizontal position, he will have reduced heatsink performance...also if he install some cover...something covering and creating problems to convection, the heat transfer to the air will be worst than we have imagined before.
I suggested to Nordic, to bias into a very small biasing point...and i hope he will not listen this amplifier with headphones using 100 miliwatts of power only...as under this power the biasing will be critical and some distortions in very low level signals may happens....the 80 to 100 miliamps biasing is much more safe..but iddle heat is bigger.....7 watts to the standard biasing...and 3 to 3.5 watts with stand by bias reduced.
Nordic environment is hot, as he told us...this turns things a little bit more problematic to heatsinking.
regards,
Carlos
Your adjustment steps are fine Nordic..also the "special reduced current biasing", to find 50 miliamps is interesting too.
The off set multimeter will be there, connected into the output line, reading DC milivolts, only during those adjustments.... all multimeters must be removed, also the protective rail resistances must be removed after you finish bias and off set adjustment.
Remember to remove the input short you have made in advance to play the amplifier.
The standard biasing is 800 to 1100 milivolts measured over 10 ohms resistance.....but your heatsinks are not so enormous as we have dreamed.... a smaller current, when iddle, can be helpfull to maintain your temperature stable.
Are you using bias resistances?...or using diodes or VBE multiplier.
Before power the amplifier, i suppose you have measured resistance from plus to ground...from negative rail to ground...from positive to negative....and all those measurements made once more, but this time with ohmeter probe points inverted in polarity referenced the first measurements made. All
reading must be high...something over 30K....this will show you that no short is present into the board construction.
Before you remove your protective pillow (ahahahah) check for possible electrolitic condenser polarity inversion...and also check once more if they are 35 volts or much more related working voltage.
Beeing carefull this way...for sure you will not have surprises...well...are you sure the positive wire is really positive?
hehe....i happens dear Nordic....more often than you can imagine.
regards,
Carlos
.......................................................................................................
Greg
The standard biasing procedure, published in our home page, is correct.
The small reduction was "arranged" as i could see Nordic draws about the amplifier case, the enclosure...depending the way he will arrange the heatsinks..if fins in vertical or horizontal position, he will have reduced heatsink performance...also if he install some cover...something covering and creating problems to convection, the heat transfer to the air will be worst than we have imagined before.
I suggested to Nordic, to bias into a very small biasing point...and i hope he will not listen this amplifier with headphones using 100 miliwatts of power only...as under this power the biasing will be critical and some distortions in very low level signals may happens....the 80 to 100 miliamps biasing is much more safe..but iddle heat is bigger.....7 watts to the standard biasing...and 3 to 3.5 watts with stand by bias reduced.
Nordic environment is hot, as he told us...this turns things a little bit more problematic to heatsinking.
regards,
Carlos
Attachments
For sure, there are errors in the construction.
Base inverted related emitter....check circuit till you discover..do not give up, as there are errors.
It is normal to check, also double check, and not to observe that assembled transistors in the wrong way.
I have made that more than hundred times...
as i have constructed many amplifiers....experience do not make you better than others....the difference is that you will insist,beeing sure, that human errors are normal.
Please inform, once again, the transistors you are using....BC640 is a hell complicated, as i could find two different diagrams of leads in two different factories.
regards,
Carlos
Base inverted related emitter....check circuit till you discover..do not give up, as there are errors.
It is normal to check, also double check, and not to observe that assembled transistors in the wrong way.
I have made that more than hundred times...
as i have constructed many amplifiers....experience do not make you better than others....the difference is that you will insist,beeing sure, that human errors are normal.
Please inform, once again, the transistors you are using....BC640 is a hell complicated, as i could find two different diagrams of leads in two different factories.
regards,
Carlos
Attachments
Observe that some brands have different pin conections
If you are using one of those ones, better to check the base with our Multimeter.
Diode position...the base will be the one that will conduct to other leads.....and also will not conduct if you invert probe point polarity.
regards,
Carlos
If you are using one of those ones, better to check the base with our Multimeter.
Diode position...the base will be the one that will conduct to other leads.....and also will not conduct if you invert probe point polarity.
regards,
Carlos
Attachments
oh man - i am having my
fingers crossed for good luck in powering this little "beast"....good luck Nordic....
Carlos has made an extremely fine piece of audio equipment here - You can count on it....
stabile,
easy to make,
relatively cheap also,
clever designed,
maaannnnnnn
it is hard to beat this nice and easy design...
fingers crossed for good luck in powering this little "beast"....good luck Nordic....
Carlos has made an extremely fine piece of audio equipment here - You can count on it....
stabile,
easy to make,
relatively cheap also,
clever designed,
maaannnnnnn
it is hard to beat this nice and easy design...
Thank you Sparkle, a nice congratulation the one you post.
I felt the same Sparkle..when doing this one, the Dx amplifier...was hard to make another amplifier so good as Aksa...i could not...Aksa is even better in treble and sound stage....i could have more power, a sligthly better voice and much more bass.
Now you are designing yours...you will face those things too.
Only simulating is very easy..we can produce 100 in a day...but listening, evaluating each modification, each option...CCS or not CCS.... mirror or not mirrored.... output darlington or triple darlington....evaluating each possible option, the way you are doing and studying, will produce, certainly a very good amplifier...but the work is hard.
regards,
Carlos
.......................................................................................................
Dear Nordic...you have a short....12 ohms...hehe...transistors shorted, burned, copper lines producing shorts....you will find.
Take a breath..go to sleep for some minutes...or wait a couple of days, if tired, and return to hunt..you will find.
regards,
Carlos
I felt the same Sparkle..when doing this one, the Dx amplifier...was hard to make another amplifier so good as Aksa...i could not...Aksa is even better in treble and sound stage....i could have more power, a sligthly better voice and much more bass.
Now you are designing yours...you will face those things too.
Only simulating is very easy..we can produce 100 in a day...but listening, evaluating each modification, each option...CCS or not CCS.... mirror or not mirrored.... output darlington or triple darlington....evaluating each possible option, the way you are doing and studying, will produce, certainly a very good amplifier...but the work is hard.
regards,
Carlos
.......................................................................................................
Dear Nordic...you have a short....12 ohms...hehe...transistors shorted, burned, copper lines producing shorts....you will find.
Take a breath..go to sleep for some minutes...or wait a couple of days, if tired, and return to hunt..you will find.
regards,
Carlos
I feel so stupid, just can't find my mistake... just finished printing greg's boards to transparency, was going to etch his power relay controller tommorrow anyway...might as well do the right thing...
Now I'm going to race a bit on Trackmania to relax then I will sit one more session with the board... cleaned up my desk nicely for it now...hope I have enough paste left to reattach transistors...
But I intend to ask the transformer place for some thermal paste as well as the discount...
I am not terribly dissapointed, about 4 out of 10 things I build works straight off... luckily normaly those include my main amps...
but with experimental boards I learned many new words due to carelessness... but I tried to be very carefull with the DX board, (will call it DXA from now on for DX Amp).
I know this amp will be good when its done, not because of schematics, but because I know when and who to trust.
Sadly I will be very short of time over the next few weeks, and any time spend on the amp, will actualy be stolen from the project that has to pay for it all... I am so glad I overcame the impatience of my early 20's nowadays I can sit and enjoy the thougth of something for long until I actualy have it...
I intend working on the amp during coffee and afternoon breaks... although tommorow is some public holiday again... so I can be as busy as the wife lets me be...
Will have to make good use of my time tonight to prepare photoresist boards etc so I can get a move on. I'd like to have at least one channel ready before the transformers arrive...
Carlos it seems that the Rails for 24V transformer sit closer to 31V after rectification and filtering than 35V... any adjustments you reccommend?
Now I'm going to race a bit on Trackmania to relax then I will sit one more session with the board... cleaned up my desk nicely for it now...hope I have enough paste left to reattach transistors...
But I intend to ask the transformer place for some thermal paste as well as the discount...
I am not terribly dissapointed, about 4 out of 10 things I build works straight off... luckily normaly those include my main amps...
but with experimental boards I learned many new words due to carelessness... but I tried to be very carefull with the DX board, (will call it DXA from now on for DX Amp).
I know this amp will be good when its done, not because of schematics, but because I know when and who to trust.
Sadly I will be very short of time over the next few weeks, and any time spend on the amp, will actualy be stolen from the project that has to pay for it all... I am so glad I overcame the impatience of my early 20's nowadays I can sit and enjoy the thougth of something for long until I actualy have it...
I intend working on the amp during coffee and afternoon breaks... although tommorow is some public holiday again... so I can be as busy as the wife lets me be...
Will have to make good use of my time tonight to prepare photoresist boards etc so I can get a move on. I'd like to have at least one channel ready before the transformers arrive...
Carlos it seems that the Rails for 24V transformer sit closer to 31V after rectification and filtering than 35V... any adjustments you reccommend?
You will laugh from yourself when discover.
The error is in front of your eyes....clear to be seen.
But we watch and we do not see...this is very normal.
Let it rest...maybe looking once more you will discover that you have installed a NPN in the place of a PNP...or other transistor that has no relations with this amplifier.
relax..this is only an amplifier..you are a man..you can fix all the mistakes you have produced.
regards,
Carlos
The error is in front of your eyes....clear to be seen.
But we watch and we do not see...this is very normal.
Let it rest...maybe looking once more you will discover that you have installed a NPN in the place of a PNP...or other transistor that has no relations with this amplifier.
relax..this is only an amplifier..you are a man..you can fix all the mistakes you have produced.
regards,
Carlos
When I first power up a new amplifier I try it on 9V batteries.
I don't worry about output bias, and nothing is likely to blow using battery power.
This gives an opportunity to feel if anything becomes warm or hot, also to go in with a voltmeter to see where the current is being wrongly drawn.
At least this way you can write voltages on the circuit diagram and sit back to puzzle it out.
Good Luck Nordic.
I don't worry about output bias, and nothing is likely to blow using battery power.
This gives an opportunity to feel if anything becomes warm or hot, also to go in with a voltmeter to see where the current is being wrongly drawn.
At least this way you can write voltages on the circuit diagram and sit back to puzzle it out.
Good Luck Nordic.
Too much small voltage Dear Nordic.
Make your testings with your Chip amplifier supply....just pick three wires and use them.
Using 9 volts you have a current unballance under a ratio of 7 to 1...bigger current in the positive rail.... positive rail consumption goes to 70 miliamps.
If battery is not good enougth.... draining this current will result in even lower voltage to the amplifier...if i understood you method
regards,
Carlos
Make your testings with your Chip amplifier supply....just pick three wires and use them.
Using 9 volts you have a current unballance under a ratio of 7 to 1...bigger current in the positive rail.... positive rail consumption goes to 70 miliamps.
If battery is not good enougth.... draining this current will result in even lower voltage to the amplifier...if i understood you method
regards,
Carlos
If you wanna use 9 volts with Dx amplifier, i have to tell you that it will work fine
Will produce 5.5 Watts rms.
Will need more than 500 miliamps each one of those 9 volts rails
You will need to adjust the offset trimpot to zero.... a very small resistance, also R7 will need replacement for a 3K9 unit, C8 will need a replacement for a 100uf unit and R10 will need replacement to 12K.
Your offset will be around 7 milivolts.
Without those needed modifications to adapt the amplifier to a very "exotic" need...you will have severe current unballance (7 by one is the ratio, bigger to positive rail)...enormous off set voltage... incredible distortions and giant sensitivity.
My dear Nordic...have to tellya.....your needs are very crazy!
- "Dx amplifier will work fine, even in the hands of crazy folks!"
*Marketing Group, Nashville Office, number 03E9956774875748
regards,
Carlos
Will produce 5.5 Watts rms.
Will need more than 500 miliamps each one of those 9 volts rails
You will need to adjust the offset trimpot to zero.... a very small resistance, also R7 will need replacement for a 3K9 unit, C8 will need a replacement for a 100uf unit and R10 will need replacement to 12K.
Your offset will be around 7 milivolts.
Without those needed modifications to adapt the amplifier to a very "exotic" need...you will have severe current unballance (7 by one is the ratio, bigger to positive rail)...enormous off set voltage... incredible distortions and giant sensitivity.
My dear Nordic...have to tellya.....your needs are very crazy!
- "Dx amplifier will work fine, even in the hands of crazy folks!"
*Marketing Group, Nashville Office, number 03E9956774875748
regards,
Carlos
- Status
- Not open for further replies.