AndrewT said:
Hi Andrew,
I've put the 68p mica caps in place of the 47p ceramic discs, and still getting 3mV AC (no DC at all) from output to ground.
I powered and measured one channel at a time, boards fitted into the case, ground to the chassis star, input also shorted to chassis star, and heatsinks also grounded. Each channel measures the same, and still getting that buzz with the volume right up, but no hum.
Cheers,
Darren
EDIT: on Carlos' advice I also gave the boards a good look over and resoldered anything that looked amiss.
3mV of noise and buzz on the output is a disaster.
1mV is poor.
0.2mV is good.
<0.1mV is very good and often achievable.
But, as soon as I put an amp in a case it invariably becomes noisier than sitting bare. Often degenerating from <0.05mV to 0.5mV (20dB more noise) and a lot of work to get it back below 0.2mV.
1mV is poor.
0.2mV is good.
<0.1mV is very good and often achievable.
But, as soon as I put an amp in a case it invariably becomes noisier than sitting bare. Often degenerating from <0.05mV to 0.5mV (20dB more noise) and a lot of work to get it back below 0.2mV.
AndrewT said:
Hi Andrew, just measured from PSU V+ out to ground, and 3mV AC there too - should there be any AC coming out of the PSU?
Annoying thing is, though, that I don't measure any AC when it's not in the case. Must be bad earthing somewhere when everything's connected up (source selector, volume pot, etc...).
I'll give the boards an even more thorough look over this evening - thanks again Andrew.
panson_hk said:
Hi panson_hk,
Yes, I did use a wire to ground the input - will try a smaller wire next time round, and maybe use the GND spade on the board, rather than the chassis star?
Yep, measurement was with a DVM - a decent UNI-T one.
Thanks all for your tips - I'll get there!
Cheers,
Darren
I was out from the air....internet provider was not working
And it is not very good... very slow..only 60 Kbps.
Brazilian folks are bulding Dx Standard:
Bruno italiano
Renato Comerlatte
Soundbuster
Hugo Schultz
Dj Damasio
Heinrich
Gomes
Seboooso
Lumaq
Marcisio
Luislevski
Maia
Mechatronics
Bamoura
Hitech
Spanholiciro
I am happy, no one of them has faced problems with the Dx Standard....lucky guys... this is not very common, not to make some mistakes when constructing amplifiers.
70 percent of those folks use to read this forum.
regards,
Carlos
And it is not very good... very slow..only 60 Kbps.
Brazilian folks are bulding Dx Standard:
Bruno italiano
Renato Comerlatte
Soundbuster
Hugo Schultz
Dj Damasio
Heinrich
Gomes
Seboooso
Lumaq
Marcisio
Luislevski
Maia
Mechatronics
Bamoura
Hitech
Spanholiciro
I am happy, no one of them has faced problems with the Dx Standard....lucky guys... this is not very common, not to make some mistakes when constructing amplifiers.
70 percent of those folks use to read this forum.
regards,
Carlos
Attachments
It is all rigth... i found 300 miliamperes excelent sonics.
But the unit is sounding great when you adjust toe 60 miliamperes, or 100 miliamperes, or 130 miliamperes.
I found it warmer, more precise, better when i have increased..but for sure the heatsinks turns very hot.
My suggestion is to folks to try, to give a try, to see if they like, to see if their heatsinks will hold the heat... to evaluate.
Just that...it is up to you folks, your amplifier, and sound fine with bias from 25 miliamperes to 3 amperes... i just found 300 ma as the best sound.
But really..... aaagh!..... too much hot to my home.... really hot!
be happy...enjoy your amplifier..sing and dance folks!
You know... soon i will open a thread about HRII...i am collecting a lot of things to comment, will be helpfull to some folks are building.... almost unbeliavable, i was saying Greg and Nico their home pages will not be needed anymore, because amplifier are old, a lot of folks already made them...so...probably no one will be interested anymore and i am perceiving a "rush or Hush..big traffic, big transit" about those amplifiers....the HRII and Dx Amplifier.
This current is for HRII only!
I felt those folks were dead.... ressurrection?
regards,
Carlos
But the unit is sounding great when you adjust toe 60 miliamperes, or 100 miliamperes, or 130 miliamperes.
I found it warmer, more precise, better when i have increased..but for sure the heatsinks turns very hot.
My suggestion is to folks to try, to give a try, to see if they like, to see if their heatsinks will hold the heat... to evaluate.
Just that...it is up to you folks, your amplifier, and sound fine with bias from 25 miliamperes to 3 amperes... i just found 300 ma as the best sound.
But really..... aaagh!..... too much hot to my home.... really hot!
be happy...enjoy your amplifier..sing and dance folks!
You know... soon i will open a thread about HRII...i am collecting a lot of things to comment, will be helpfull to some folks are building.... almost unbeliavable, i was saying Greg and Nico their home pages will not be needed anymore, because amplifier are old, a lot of folks already made them...so...probably no one will be interested anymore and i am perceiving a "rush or Hush..big traffic, big transit" about those amplifiers....the HRII and Dx Amplifier.
This current is for HRII only!
I felt those folks were dead.... ressurrection?
regards,
Carlos
Hi, Carlos.
Just walking around at the moment.
Hi, Mod.
Try this post:
http://www.diyaudio.com/forums/showthread.php?postid=1324642#post1324642
Did you have read this thread since first message? I´m trying... still on page 70.
Hi, All.
Although Carlos already knows me, this is my first post. I have knowledge about electronics and I´m beginning in DIY Audio.
Best regards.
Just walking around at the moment.
Hi, Mod.
Try this post:
http://www.diyaudio.com/forums/showthread.php?postid=1324642#post1324642
Did you have read this thread since first message? I´m trying... still on page 70.
Hi, All.
Although Carlos already knows me, this is my first post. I have knowledge about electronics and I´m beginning in DIY Audio.
Best regards.
Greg Erskine said:
Greg! Thanks, this is the site that I was searching.
I will make a DX Amp to have some fun with transistors because some friends asked me what amplifier is good to them make and I will test the DX amp to reccomend to them.
I will use a 30+30vAC 8A Xformer to make the power supply.
When I finish mine final test I will begin making the DX Amp.
Best Regards,
Felipe
Carlos como posso falar contigo? How can I talk with you, carlos?
Try the Aksa... the schematic published in this same forum
And you can tweak to sound the way you like.
I saw you once giving advises to PMA, and as PMA is a very good enginneer, someone that use to design instruments to check amplifiers, and you said him to use a capacitor, in this thread down here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=35899&perpage=25&highlight=&pagenumber=1
Seems to me your are a very superior in knowledge..someone that knows the real thing...reason why i cannot help you...i have not that know how to support your excelency.
You like tube amplifiers, you said once they are better...and i agree with you....so... the Aksa has features that sounds alike tube amplifiers, in special if you discover some tricks.
Well...to discover have first of all to move and to build..and them to produce clever research.
My poor Dx Amplifier cannot beat an electronic tube amplifier...i think you gonna waste your time.
I know you from the past...your mind is brainwashed to tubes...so..why to loose your precious time?
here is the Aksa schematic...please, do not build my amplifier...we both will be more happy this way.... instead of that try Kleindschmidt amplifier or Andrew T amplifier...more modern and more adequated to your superior knowledge.
regards,
Carlos
And you can tweak to sound the way you like.
I saw you once giving advises to PMA, and as PMA is a very good enginneer, someone that use to design instruments to check amplifiers, and you said him to use a capacitor, in this thread down here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=35899&perpage=25&highlight=&pagenumber=1
Seems to me your are a very superior in knowledge..someone that knows the real thing...reason why i cannot help you...i have not that know how to support your excelency.
You like tube amplifiers, you said once they are better...and i agree with you....so... the Aksa has features that sounds alike tube amplifiers, in special if you discover some tricks.
Well...to discover have first of all to move and to build..and them to produce clever research.
My poor Dx Amplifier cannot beat an electronic tube amplifier...i think you gonna waste your time.
I know you from the past...your mind is brainwashed to tubes...so..why to loose your precious time?
here is the Aksa schematic...please, do not build my amplifier...we both will be more happy this way.... instead of that try Kleindschmidt amplifier or Andrew T amplifier...more modern and more adequated to your superior knowledge.
regards,
Carlos
Attachments
You see Moody, when i want to watch the blue electronic colour from electron flow
I have to use some Blue Leds.
In my poor home there's no tube...exception the television set tube.
We have a nice forum about tubes...you should go there to teach folks how to build electronic tubes devices...gonna be helpfull there.
largadumeupeh ... "Do not follow me, i have nothing to contribute with you"...in a simple brazilian way to speak.
Bye!
Carlos
I have to use some Blue Leds.
In my poor home there's no tube...exception the television set tube.
We have a nice forum about tubes...you should go there to teach folks how to build electronic tubes devices...gonna be helpfull there.
largadumeupeh ... "Do not follow me, i have nothing to contribute with you"...in a simple brazilian way to speak.
Bye!
Carlos
Attachments
Nice Mooly... i will eat pig meat during christmas
Chester too....that big bird US folks loves...the same you use to eat.... Turkey?
Will avoid cow meat.... you gonna be more happy this next Christmas.
I love pig upper leg... tender... ham.... with honey, pineaples and apples..the only sweet together salt i use to eat...only during Christmas..and the Italian Panettone (bread with dried fruits).
I love Christmas..we have not snow, only the extreme Southern states have into mountain towns... ice, snow and all stuff...a pitty that i am into the hottest place in Brazil...not so different compared to Florida.
regards,
Carlos
Chester too....that big bird US folks loves...the same you use to eat.... Turkey?
Will avoid cow meat.... you gonna be more happy this next Christmas.
I love pig upper leg... tender... ham.... with honey, pineaples and apples..the only sweet together salt i use to eat...only during Christmas..and the Italian Panettone (bread with dried fruits).
I love Christmas..we have not snow, only the extreme Southern states have into mountain towns... ice, snow and all stuff...a pitty that i am into the hottest place in Brazil...not so different compared to Florida.
regards,
Carlos
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