Professor smith
If you still not sure who to believe, just chose to listen to one or two persons and stick closely to what they said, Hugh would be the first, and for a second one I can suggest anatech who have a deep experience in electronics.
Bye
Gaetan
If you still not sure who to believe, just chose to listen to one or two persons and stick closely to what they said, Hugh would be the first, and for a second one I can suggest anatech who have a deep experience in electronics.
Bye
Gaetan
Professor smith said:
If source means CD player then I use a Cambridge 840C and a Sony CDP-X55ES in the AKSA system.
The output I have at the transformer secondaries should be 50vac but i am getting a reading of 59v.
So what is going on here?
So what is going on here?
Interesting.... AndrewT have disappeared...and believe me or not
I am missing him. (Stockolm syndrome)
Interesting those things...he used to make those kind of questions Professor makes.
Maybe this is because i am missing him.... he used to answer, and professor makes questions.
They are very complementary in my mind.
I hope AndrewT is fine.
regards,
Carlos
I am missing him. (Stockolm syndrome)
Interesting those things...he used to make those kind of questions Professor makes.
Maybe this is because i am missing him.... he used to answer, and professor makes questions.
They are very complementary in my mind.
I hope AndrewT is fine.
regards,
Carlos
At last a measurement I asked fore long ago
Could you please measure each rail
positive to ground and negative to ground
And please on both channels
And make precise note of each one
Could you please measure each rail
positive to ground and negative to ground
And please on both channels
And make precise note of each one
Re: Interesting.... AndrewT have disappeared...and believe me or not
Hello Carlos
AndrewT is fine, he did post in a chip amp thread last friday.
Bye
Gaetan
destroyer X said:
Hello Carlos
AndrewT is fine, he did post in a chip amp thread last friday.
Bye
Gaetan
Hello Professor smith
There is a good thread about grounding and noise;
http://www.diyaudio.com/forums/showthread.php?s=&threadid=115698&perpage=25&pagenumber=1
Bye
Gaetan
There is a good thread about grounding and noise;
http://www.diyaudio.com/forums/showthread.php?s=&threadid=115698&perpage=25&pagenumber=1
Bye
Gaetan
Professor smith said:
NAD C162
No hum, buzz or other nasties. I have a layout as you've seen with signal and speaker wiring at the back with transformers and power supply at the front. That way the signal etc are not close to any AC or DC power wires. Very similar to the clear case amp that's just been posted in the AKSA thread.
re post 206.Professor smith said:
The PCBs have male spade connectors soldered in.
The new interconnections should have female spade connectors crimped on to clean copper wire ends.
This avoids the difficulty of heating those big speaker wires and spades up to a high temperature to ensure correct soldering.
It also makes correction so much easier if the wiring is wrong.
It also makes disconnection easy to go back a stage and measure what you have, before adding complicated extra circuitry.
Re: Re: Interesting.... AndrewT have disappeared...and believe me or not
finished dancing at:
0430hrs Friday night/Saturday morning.
0330hrs Saturday night/Sunday morning.
0615hrs Sunday night/Monday morning.
I'm home in one piece and my feet survived.
I think I can still think. Maybe?
I have been away on a Jive weekender.gaetan8888 said:
finished dancing at:
0430hrs Friday night/Saturday morning.
0330hrs Saturday night/Sunday morning.
0615hrs Sunday night/Monday morning.
I'm home in one piece and my feet survived.
I think I can still think. Maybe?
heheheh... this was fine... a very human way to have fun
yeah..i like that.... but tell me..how many dance steps have you made..have you counted them?
ahahahhahaahha!
regards,
Carlos
yeah..i like that.... but tell me..how many dance steps have you made..have you counted them?
ahahahhahaahha!
regards,
Carlos
off topic
I took a step counter with me to a class night.
9500 steps in 3hrs.
second class night 10300steps in 3hrs.
did a party night on the Saturday and >20000steps in 4.5hrs
I'm fitter now, that was a couple of years ago.
Sorry, to all those that have to read this trash.
I took a step counter with me to a class night.
9500 steps in 3hrs.
second class night 10300steps in 3hrs.
did a party night on the Saturday and >20000steps in 4.5hrs
I'm fitter now, that was a couple of years ago.
Sorry, to all those that have to read this trash.
would it be possible to adjust the bias by freehand? meaning twist the trimpot 30degrees then measure and see what happens? I am assuming that the trimpots are sufficiently fine to be able to do it like this.
The present bias for both channels are 75mv and 73.5mv and they ought to be 55mv.
Would I be able to get them down to 55mv in this way?
I dont have a clip on DMM so i would have to adjust then measure then adjust then measure and so on..
The reason i want to tweak the bias is because I suspect this might be why i am (still) getting a variation in the sound.
The present bias for both channels are 75mv and 73.5mv and they ought to be 55mv.
Would I be able to get them down to 55mv in this way?
I dont have a clip on DMM so i would have to adjust then measure then adjust then measure and so on..
The reason i want to tweak the bias is because I suspect this might be why i am (still) getting a variation in the sound.
That really is not a significant bias error. If that accounted for a difference in sound it is a poorly designed amplifier. Which it isn't.
Yes, you can adjust and measure, but chose a very small increment to ensure you are going in the right direction.
Yes, you can adjust and measure, but chose a very small increment to ensure you are going in the right direction.
Hugh or Carlos,
can you please help? i am faced with another precarious situation. I have turned the trimpot a good half to full turn (anti clockwise) and this has only dropped the bias from 76 to 75mv.
If a full turn equates to 1mv drop, then it woud require in the order of 20 turns CCW to get it to 55mv?
This cant be right.
can you please help? i am faced with another precarious situation. I have turned the trimpot a good half to full turn (anti clockwise) and this has only dropped the bias from 76 to 75mv.
If a full turn equates to 1mv drop, then it woud require in the order of 20 turns CCW to get it to 55mv?
This cant be right.
Maybe you have turned the DC adjust, and not the bias
Without distortion measurements, adjustment may not mean much anyway
Touch the heatsink and "measure" how hot
That big heatsink ought not be very hot
Personally I adjust only by listening, and monitor heat
Ofcourse I measure bias as well, but only fore precaution
Maybe design depending, but I have always found bias pots to be exstremely sensitive
Sometimes you cant barely touch them without bias change
I am not suggeting to do it that way, its only how I do it
Be very carefull not to touch anything, or you risk a burned amp
Use nothing else than secure and fully isolated "probes"
I would only use a 100% nonmagnetic screwdriver
Maybe make your own from a piece of steel wire
I use one of those you use fore building racebike wheels
Without distortion measurements, adjustment may not mean much anyway
Touch the heatsink and "measure" how hot
That big heatsink ought not be very hot
Personally I adjust only by listening, and monitor heat
Ofcourse I measure bias as well, but only fore precaution
Maybe design depending, but I have always found bias pots to be exstremely sensitive
Sometimes you cant barely touch them without bias change
I am not suggeting to do it that way, its only how I do it
Be very carefull not to touch anything, or you risk a burned amp
Use nothing else than secure and fully isolated "probes"
I would only use a 100% nonmagnetic screwdriver
Maybe make your own from a piece of steel wire
I use one of those you use fore building racebike wheels
Gawd,
Here we go again......
Kenji,
Bias adjustment on a bipolar Class AB amp is not linear. Little happens for a time, then it all comes in with a rush. I have deliberately constrained the adjustment band to avoid ham fisted misadjustments which might otherwise destroy the output devices with 10A bias currents.
You may turn the trimpot as much as you like, it will do no damage. It may not go as low as 55mV (58mA), it may only go down to 60mV. But this will NOT affect the sound quality, as I have told you perhaps three times now.
More bias, rather than less, is quite OK and will actually marginally improve the bass output. There will be no other effect.
Andrew, the pedometer is fine and dandy for vertical dancing. Did you measure it for the horizontal step too? You should publish the results..... pardon me, my lewd Oz humour......
Cheers,
Hugh
Here we go again......
Kenji,
Bias adjustment on a bipolar Class AB amp is not linear. Little happens for a time, then it all comes in with a rush. I have deliberately constrained the adjustment band to avoid ham fisted misadjustments which might otherwise destroy the output devices with 10A bias currents.
You may turn the trimpot as much as you like, it will do no damage. It may not go as low as 55mV (58mA), it may only go down to 60mV. But this will NOT affect the sound quality, as I have told you perhaps three times now.
More bias, rather than less, is quite OK and will actually marginally improve the bass output. There will be no other effect.
Andrew, the pedometer is fine and dandy for vertical dancing. Did you measure it for the horizontal step too? You should publish the results..... pardon me, my lewd Oz humour......
Cheers,
Hugh
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