Well I found the problem with my second channel. I had 8r2 where I supposed to have 8K2. Funny thing is this channel has only 9mvdc offset. So now that I've got them both working, I hook up my bigger transformer with four 10,000 caps and hooked up the first channel. Well, not so good. I have the bias pot all the way up and I can't stop the amps from rising so I shut it down. I put it aside and hookup the channel I just fixed and carefully bring it up on the variac. No problems. I can actually set the bias to 100ma which gives me about 16mv across an output pair. I did notice the offset rising and got all the way up to 40mvdc when I felt the VAS heatsink and it was very hot. I grabbed a little fan and put it on the VAS and the offset dropped back down to 9mv. Looks like I will need to put a much larger sink there. I've had it playing for an hour now and everything looks and sound really good. Now to take some voltage measurements so I can figure out what is wrong with the first channel.
Blessings, Terry
Blessings, Terry
Nice gray multimeters Terry
I see you have the stuff under control...so..... it is all right
I wish all people that assemble my amplifiers have your knowledge...this would be very relaxing to me... you are able to figure out any kind of trouble.
Skilled guy...... very good.
You see...i am watching the multimeters....i have no worries that everything gonna be all right.
I am removing drivers from the heatsink in high power amplifiers.... i realise if they become hot they produce thermal drift...so, i am installing them, now a days, with their own vertical heatsinks..... VAS is even more sensitive....i do not let them operate with temperatures higher than 45 degrées celsius.
This amplifiers is flat, naturally, but the sonic signature is very interesting...you will perceive this clearly.
Remember we have losses in high frequency because aged ears... this is something usefull to remember.... you see we do not hear horizontal frequency of tube television anymore..... you see something misterious happening while listening.
regards,
Carlos
I see you have the stuff under control...so..... it is all right
I wish all people that assemble my amplifiers have your knowledge...this would be very relaxing to me... you are able to figure out any kind of trouble.
Skilled guy...... very good.
You see...i am watching the multimeters....i have no worries that everything gonna be all right.
I am removing drivers from the heatsink in high power amplifiers.... i realise if they become hot they produce thermal drift...so, i am installing them, now a days, with their own vertical heatsinks..... VAS is even more sensitive....i do not let them operate with temperatures higher than 45 degrées celsius.
This amplifiers is flat, naturally, but the sonic signature is very interesting...you will perceive this clearly.
Remember we have losses in high frequency because aged ears... this is something usefull to remember.... you see we do not hear horizontal frequency of tube television anymore..... you see something misterious happening while listening.
regards,
Carlos
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Well I don't know about how skilled I am but have learned that it is important to see what is going on before you see smoke. I always try to have one meter on the output, one on a rail and one set up as an ammeter if possible. With this one I had 10W 10R resistor in place of each fuse and put a meter on each and one on the output to watch the dc offset. I saw the the +rail drawing more than the - rail and when it got to about 3V the 47R resistor started smoking and I shut it down. Tomorrow should be fun tracking down the last little hiccup. If I can 't figure it out I will post the results here and sure one of you guys will know what the problem is. Hopefully I will able to figure it out on my own. From what I can hear, it will be very nice sounding amp. The Honey Badger I just finished is a Blameless baby as well and it sounds very good. Most of the parts came in today to finish the Super A so I should be listening to it soon as well.
Blessings, Terry
Blessings, Terry
I just want to say mister Terry please be patience I know you will find it after all is corrected the other channel you will enjoy nice music, from my heart mister Terry when I build my MKIII's I'm telling you music is so nice and power full, treble, bass, voices are so good I mean I love it, I know for sure you will enjoy it, and I know you will.
and last thing mister Terry did you insulate this transistors in this image?
Regards
Juan
and last thing mister Terry did you insulate this transistors in this image?
Regards
Juan
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Both channels are working but not correctly. I need work from one schematic. I think I have mixed and matched. I am currently comprising a BOM from one schematic and will work from that. If I have success I will post it here. I don't like that the VAS transistor run so hot. They affect the offset for some reason. Canonnica posted a schematic of how he has his running. I'm told his plays fine with the same rails I am using so I will try his combination.
Yes, I insulated with mica insulators and grease. My heatsink was too small. I have made a huge one but still have other issues. Once I have fixed them I will get get back to you.
Yes, I insulated with mica insulators and grease. My heatsink was too small. I have made a huge one but still have other issues. Once I have fixed them I will get get back to you.
Oh!...what a bad luck dear Terry...smoking resistors is something that annoys
a lot.
Sorry, i would be happy to be with you..sholder by sholder to help you to track this darn bug.
I will sleep a little bit sad this night...i hope tomorrow gonna be a better day..... not good news that story of smoking resistor.... something more gone to produce this increase in current.
Next ones assemble them distant from the pcboard....if they burn again while testing, then they will not burn the pcboard..these Meanman pcboards are very nice...a pity to burn them
I think you are using protective series resistor, or variac, or lamps.... of course you are.... i know you are skilled.
My internet was out from the air since early morning...problems with fiber optics...... damage on cables... i could not log in diyaudio.... i had only the cell phone, and i cannot see the screen..too much small the Galaxy screen to my old eyes.
regards,
Carlos
a lot.
Sorry, i would be happy to be with you..sholder by sholder to help you to track this darn bug.
I will sleep a little bit sad this night...i hope tomorrow gonna be a better day..... not good news that story of smoking resistor.... something more gone to produce this increase in current.
Next ones assemble them distant from the pcboard....if they burn again while testing, then they will not burn the pcboard..these Meanman pcboards are very nice...a pity to burn them
I think you are using protective series resistor, or variac, or lamps.... of course you are.... i know you are skilled.
My internet was out from the air since early morning...problems with fiber optics...... damage on cables... i could not log in diyaudio.... i had only the cell phone, and i cannot see the screen..too much small the Galaxy screen to my old eyes.
regards,
Carlos
OK well I have made some headway. I replaced the two 47R resistors that replace D1 & D3 as they were not measuring the same. The offset is fine now. I had 47R in R22. I replaced that with the 4R7 shown in the original schematic. That fixed the problem with setting the bias but the VAS still runs pretty hot. Needs the big heatsink still. My house voltage is high today and the rails are +/- 77Vdc. I hooked up the scope and it now doesn't clip until 47Vac into an 8R load which is something like 275WRMS which is way louder than I will ever play it so that weird little sticking is not likely to be a problem. The square wave still looks a little funny so I am going to try some of the fixes that Canonnica suggested. I didn't play music through it yet as I don't have it bolted to the heatsink, only the angle. I made sure not to run it long enough to over heat.
Blessings, Terry
Blessings, Terry
I have prepared this schematic Terry...maybe it gonna help
Small modifications.... transistor as heat sensor and bias adjustment i am using BD139..... 47ohms in place in the rails.... this is the traditional schematic, the most often used.
I know there are some upgrade versions, but this one was simulated now and i am sure it works fine.
If the VAS is hot is because current there is big... then reduce the current replacing the CCS reference resistor from 22 to 47 ohms..then you gonna cool down the VAS transistor and you gonna be happy.
Watch the schematic.... and be happy.
regards,
Carlos
Small modifications.... transistor as heat sensor and bias adjustment i am using BD139..... 47ohms in place in the rails.... this is the traditional schematic, the most often used.
I know there are some upgrade versions, but this one was simulated now and i am sure it works fine.
If the VAS is hot is because current there is big... then reduce the current replacing the CCS reference resistor from 22 to 47 ohms..then you gonna cool down the VAS transistor and you gonna be happy.
Watch the schematic.... and be happy.
regards,
Carlos
Attachments
Hi Ranchu
I noticed you are in Brisbane as well. Carlos was asking still4 to do an A-B comparison of his amplifier. I have some cables to do this comparison. If you'd like to get together give me a pm.
I was building the MK3 amplifier a few years ago but I never got to finishing it. Was going to use a switchmode power supply but had an issue with the PS. I got turned off the idea of more noise with a smps and never got aroud to buying a huge 1kw transformer needed for the MK3.
I've got a few diy amps here we can test with the MK3 when youve finished if you like.
I'd like to give a big Thankyou to Carlos for starting me on this Hifi amplifier learning hobby. A great teacher with a good heart.
Simon
Hi Simon
I would be very interested in meeting to do a comparison with your amps. I have a P3A that I finished a few months ago and is powering the loudspeakers in my living room.
I kinda had a "false start" in DIY audio about 10 years ago when I started building Rod's P68 subwoofer amplifier. I finished the board and nearly finished the project but lost interest due to frustration sourcing parts from Dick Smith & Jaycar back then. I got back into the hobby the beginning of these year when I assembled a pair of bookshelf speakers from "the loudspeaker kit" and then also built a small Class D amplifier from 41hz.com to fit inside the cabinet.
The project was a success so I built the P3A and now working on DX MKIII and VSSA.
I'm making slow but steady progress on my MKIII - full time job, sport, new house and 10 month old baby doesn't leave too much time in the week. The boards are stuffed and power supply is almost finished. I need to tap the heatsinks, mount the boards and finish some wiring.
I've built soft start and DC protection circuits - both on veroboard - for this project.
I like to take things slowly - double and triple checking everything as I go.
I would be very interested in meeting to do a comparison with your amps. I have a P3A that I finished a few months ago and is powering the loudspeakers in my living room.
I kinda had a "false start" in DIY audio about 10 years ago when I started building Rod's P68 subwoofer amplifier. I finished the board and nearly finished the project but lost interest due to frustration sourcing parts from Dick Smith & Jaycar back then. I got back into the hobby the beginning of these year when I assembled a pair of bookshelf speakers from "the loudspeaker kit" and then also built a small Class D amplifier from 41hz.com to fit inside the cabinet.
The project was a success so I built the P3A and now working on DX MKIII and VSSA.
I'm making slow but steady progress on my MKIII - full time job, sport, new house and 10 month old baby doesn't leave too much time in the week. The boards are stuffed and power supply is almost finished. I need to tap the heatsinks, mount the boards and finish some wiring.
I've built soft start and DC protection circuits - both on veroboard - for this project.
I like to take things slowly - double and triple checking everything as I go.
Taking your time is the only way to do it. That way less chance of mistakes. When your done building the MKIII we'll organise something. I've got a couple of DX Corp Blame st here one slightly different from the other. and also the Ostripper designed honey badger to compare it to. If it takes you another 6 months to build we could even compare them with some new speakers I am currently creating.
Simon
Attachments
This is good Niss man....you know very well how to compare
And will make a great job for the community informing the differences and also the qualities of each one of these amplifiers.
I have found that we can make good audio recordings, almost the same sound we can listen with our ears can be registered, if you use an old cell phone, the Nokia N8 or the Nokia 808...they are using a interesting technology they call Haas...and the sound is really perfect.
So, i am searching to buy an old Nokia N8, a 2010 model, as the designer is audiofile and made something usefull to us...finally we can show our amplifier qualities.... this can show people the same sound we listen at home...also accept great sound pressure without distort due to two microphones, one hard to move to high audio pressure and other very sensitive, these microphones are switched on and of in microseconds, follow the sound dinamics...you can have wispers and thunderstorms at same time without distortion...it is awesome, from outside planet.
This cell phones is being sold, in Brasil, used, by 500 USD, so good they are...ugly stuff, but with high end audio technology.
For you dear Niss man...and other audiofiles...take a good look in that precious tool:
http://www.youtube.com/watch?v=hZUbMyQl2qY
http://www.youtube.com/watch?v=EnXD2qhUAjI
http://www.youtube.com/watch?v=r774qsNrQm0
this one is very important..someone like you, Niss man, with a tool like that, gonna be the best man to compare stuff in our comunity... i would like to ask you, brothers into audio passion, to see and listen with full attention this man that gonna talk below.... we do not have oportunity to listen a genius talking...below you have.
http://www.youtube.com/watch?v=p8RHQC0eS_k
Here you have all the theory about it...i suggest you, dear Niss man, because your characteristic as a man, a brain perfectly gifted for comparison, someone very fair in the judgement, to search for a tool like that, the same way i am doing:
http://www.youtube.com/watch?v=euEQ1NNdP5U
You see the self confidence...he knows what he is doing..smashing every audio recorder...and inside a cell phone.... watch it almost laughing....this is the face of a winner!
The best demonstration, ever made, from my amplifier was recorded using a Nokia N8 cell phone... was the moment i found myself in front of my audio equipment listening music....this is the way i listen it at my home..this is the sound i listen.
http://www.youtube.com/watch?v=nhrZAOABcHM
Video is not good..but this does not mind..close you eyes, cranck the volume all the way up and you gonna be at my side, in my home... evaluating a Dx amplifier.
Thanks a lot.
regards,
Carlos
And will make a great job for the community informing the differences and also the qualities of each one of these amplifiers.
I have found that we can make good audio recordings, almost the same sound we can listen with our ears can be registered, if you use an old cell phone, the Nokia N8 or the Nokia 808...they are using a interesting technology they call Haas...and the sound is really perfect.
So, i am searching to buy an old Nokia N8, a 2010 model, as the designer is audiofile and made something usefull to us...finally we can show our amplifier qualities.... this can show people the same sound we listen at home...also accept great sound pressure without distort due to two microphones, one hard to move to high audio pressure and other very sensitive, these microphones are switched on and of in microseconds, follow the sound dinamics...you can have wispers and thunderstorms at same time without distortion...it is awesome, from outside planet.
This cell phones is being sold, in Brasil, used, by 500 USD, so good they are...ugly stuff, but with high end audio technology.
For you dear Niss man...and other audiofiles...take a good look in that precious tool:
http://www.youtube.com/watch?v=hZUbMyQl2qY
http://www.youtube.com/watch?v=EnXD2qhUAjI
http://www.youtube.com/watch?v=r774qsNrQm0
this one is very important..someone like you, Niss man, with a tool like that, gonna be the best man to compare stuff in our comunity... i would like to ask you, brothers into audio passion, to see and listen with full attention this man that gonna talk below.... we do not have oportunity to listen a genius talking...below you have.
http://www.youtube.com/watch?v=p8RHQC0eS_k
Here you have all the theory about it...i suggest you, dear Niss man, because your characteristic as a man, a brain perfectly gifted for comparison, someone very fair in the judgement, to search for a tool like that, the same way i am doing:
http://www.youtube.com/watch?v=euEQ1NNdP5U
You see the self confidence...he knows what he is doing..smashing every audio recorder...and inside a cell phone.... watch it almost laughing....this is the face of a winner!
The best demonstration, ever made, from my amplifier was recorded using a Nokia N8 cell phone... was the moment i found myself in front of my audio equipment listening music....this is the way i listen it at my home..this is the sound i listen.
http://www.youtube.com/watch?v=nhrZAOABcHM
Video is not good..but this does not mind..close you eyes, cranck the volume all the way up and you gonna be at my side, in my home... evaluating a Dx amplifier.
Thanks a lot.
regards,
Carlos
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As i said before, i am busy... but i will come here to watch the evolution
I have to finish today afternoon, this is a bi amplification, a monaural monitoring amplifier for computer and to play some music naturally.
One channel is Dx Boom, we have an active filter in the input, a low pass filter and the other channel of the biamp monaural system, a Dx Super A, Brazilian first group buy pcboards.
This will produce 25 plus 25 watts RMS, low distortion and will have separate volume knobs.
Output will go to a speaker with bi wiring...one for woofer and other for the mids and treble, this way they guy can adjust and select, this way, voices or music..when voices you reduce the subwoofer amplification channel.
This is for my family...not to my use.....in my computer i am using an olde Dx Blame ST
regards,
Carlos
I have to finish today afternoon, this is a bi amplification, a monaural monitoring amplifier for computer and to play some music naturally.
One channel is Dx Boom, we have an active filter in the input, a low pass filter and the other channel of the biamp monaural system, a Dx Super A, Brazilian first group buy pcboards.
This will produce 25 plus 25 watts RMS, low distortion and will have separate volume knobs.
Output will go to a speaker with bi wiring...one for woofer and other for the mids and treble, this way they guy can adjust and select, this way, voices or music..when voices you reduce the subwoofer amplification channel.
This is for my family...not to my use.....in my computer i am using an olde Dx Blame ST
regards,
Carlos
Attachments
This amplifier, the MKIII, it is not a toy
Depending you supply power, your supply voltage multiplied by the current then you can reach 1 kilowatt at 2 ohms. (distorted)
All depends on your supply...if your supply is 10 watts...then you gonna have 3.2 plus 3.2 watts RMS
It is a 200, 400 and 780 watts RMS amplifier (8, 4 and 2 ohms) if you want 0.005% distortion (THD) or even less....but if you accept some distortion you will see the hell in earth.
So...be aware... it is a monster.. take care of ventilation, heatsink size, trainees mounted directly into the heatsink and take care of your home itself...because will shake everything inside your walls at home.
Plays really loud!
regards,
Carlos
Depending you supply power, your supply voltage multiplied by the current then you can reach 1 kilowatt at 2 ohms. (distorted)
All depends on your supply...if your supply is 10 watts...then you gonna have 3.2 plus 3.2 watts RMS
It is a 200, 400 and 780 watts RMS amplifier (8, 4 and 2 ohms) if you want 0.005% distortion (THD) or even less....but if you accept some distortion you will see the hell in earth.
So...be aware... it is a monster.. take care of ventilation, heatsink size, trainees mounted directly into the heatsink and take care of your home itself...because will shake everything inside your walls at home.
Plays really loud!
regards,
Carlos
I could not do too much this sunday
People visiting me... exactly the one wants the amplifier..but no way to assemble things and talk.
But i have managed to find some time to reassemble the MKIII...i want to take a look in the waveform.
You see..it is assembled in the background.
regards,
Carlos
People visiting me... exactly the one wants the amplifier..but no way to assemble things and talk.
But i have managed to find some time to reassemble the MKIII...i want to take a look in the waveform.
You see..it is assembled in the background.
regards,
Carlos
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Joined 2009
Paid Member
Are you able to do the full output stage Carlos , interesting to see how the VAS looks fully loaded ...
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