This is good to know that you could improve it
Your work will help others to improve their units too.
regards,
Carlos
Your work will help others to improve their units too.
regards,
Carlos
Also would like to add that I was using a 1.0uF polypropylene capacitor for the input capacitor, and this worked great.
Then, I used a 10uF Nichicon Muse bipolar capacitor and found the bass was more controlled and had more impact. The low-pass filter calculations showed that technically the 1uF cap did not degrade the bass response of the amplifier. I did not notice more bass with the larger capacitor. But, I did notice more accurate or.... controlled bass. Wasn't sure why.
Now I am using the Rod Elliot "Death of Zen" Class A preamp (Project 37A), and am using a 22uF Muse BP capacitor on the output of that with a jumper in the place of the input cap of the Dx Precision. Bass became even better, along with other aspects of the sound, when using this setup.
Source before preamp is usually PC integrated sound with ASIO4ALL+J.River Media Center.
The DOZ preamp was built with about half of the gain of the standard design.
Then, I used a 10uF Nichicon Muse bipolar capacitor and found the bass was more controlled and had more impact. The low-pass filter calculations showed that technically the 1uF cap did not degrade the bass response of the amplifier. I did not notice more bass with the larger capacitor. But, I did notice more accurate or.... controlled bass. Wasn't sure why.
Now I am using the Rod Elliot "Death of Zen" Class A preamp (Project 37A), and am using a 22uF Muse BP capacitor on the output of that with a jumper in the place of the input cap of the Dx Precision. Bass became even better, along with other aspects of the sound, when using this setup.
Source before preamp is usually PC integrated sound with ASIO4ALL+J.River Media Center.
The DOZ preamp was built with about half of the gain of the standard design.
Yep, i have found the same results with Nichicon capacitors
and resulted better controled bass, maybe because of phase..i really do not know why too.... bass was not increased in level but resulted more controled.... you have agreement on that.
The surprise to me is that preamplifiers increased sonics...usually they kill sonics because of the introduction of circuits...the less stages use to give me better results...this surprised me a lot.
Thank you as you are sharing your comparative tests with us... listening tests are something i believe and deeply appreciate.
These things are interesting.... these results are very interesting... you know, i could not accept that using salt while making a cake could result fine.... cake was sweet and salt looked to be crazy...but i had to accept resulted fine in some cakes i have prepared in my home.... salt mixed with sugar worked great!.... things that looks non sense sometimes works great..... we must be opened to these things.... i am old but still learning things.
My daughter is being almost forced to study english, she has a teacher that comes to my home twice a week, i call him "home teacher" because "home theater" sounds alike... she hates to study english and i thought she would never learn...well...i was wrong... 3 years passed and she understand and speaks better than i can...i thought someone that dislike something cannot learn...but they can learn even hating a language.... strange things happens.... was lovely to see her speaking with her cousin that leave in England.... fluently while i was having troubles to understand my nephew.
Interesting... Rodd pre amplifier uses ICs... and usually ICs have a lot of parts inside...so...they would kill sonics, not because they are Rodd design (he is very good), but because ICs small internal distances..input nearby the output, huge compensation not to oscilate..well.... a lot of distorting parts inside..also the IC distortion itself..... and you found that good.... would be easy to me to think you have had too much beers..but is a very stupid way to denie and reduce tests value...and i will not be so stupid thinking this way....i will understand that may exist something there i do not know..and i will assemble Rodd preamplifier to check...please, send me the link to your preamplifier as i will give a try on it.
Picture show my daughters...i have a 19 years old son too....my daughters are single and the front left one is the ones speaks english....others speaks spanish and french.... underwater are fishes that comes to bite your fingers.
regards,
Carlos
and resulted better controled bass, maybe because of phase..i really do not know why too.... bass was not increased in level but resulted more controled.... you have agreement on that.
The surprise to me is that preamplifiers increased sonics...usually they kill sonics because of the introduction of circuits...the less stages use to give me better results...this surprised me a lot.
Thank you as you are sharing your comparative tests with us... listening tests are something i believe and deeply appreciate.
These things are interesting.... these results are very interesting... you know, i could not accept that using salt while making a cake could result fine.... cake was sweet and salt looked to be crazy...but i had to accept resulted fine in some cakes i have prepared in my home.... salt mixed with sugar worked great!.... things that looks non sense sometimes works great..... we must be opened to these things.... i am old but still learning things.
My daughter is being almost forced to study english, she has a teacher that comes to my home twice a week, i call him "home teacher" because "home theater" sounds alike... she hates to study english and i thought she would never learn...well...i was wrong... 3 years passed and she understand and speaks better than i can...i thought someone that dislike something cannot learn...but they can learn even hating a language.... strange things happens.... was lovely to see her speaking with her cousin that leave in England.... fluently while i was having troubles to understand my nephew.
Interesting... Rodd pre amplifier uses ICs... and usually ICs have a lot of parts inside...so...they would kill sonics, not because they are Rodd design (he is very good), but because ICs small internal distances..input nearby the output, huge compensation not to oscilate..well.... a lot of distorting parts inside..also the IC distortion itself..... and you found that good.... would be easy to me to think you have had too much beers..but is a very stupid way to denie and reduce tests value...and i will not be so stupid thinking this way....i will understand that may exist something there i do not know..and i will assemble Rodd preamplifier to check...please, send me the link to your preamplifier as i will give a try on it.
Picture show my daughters...i have a 19 years old son too....my daughters are single and the front left one is the ones speaks english....others speaks spanish and french.... underwater are fishes that comes to bite your fingers.
regards,
Carlos
Attachments
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Minimalist Discrete Hi-Fi Preamp
That is the link to the preamp. Actually Carlos it is not an IC design but rather a minimalist class A preamp only using 4 transistors. If you build it I think you will like it. It would only take a small amount of time. Only needs a +-15v supply capable of a few milliamps.
Thanks Carlos.
Again a slow progress here, working father is not a good idea but seeing cute smiles from those lil angels of mine afterwork is priceless.
Going to do the wirings, will report the result later.
Good evening all.
Fire up the assembled amp today and got fried transistors, BD139 and BD140 gone, Zener diode 22v and 33V both supply rails died too (shorted). Any help will be appreciated. Thanks.
Fire up the assembled amp today and got fried transistors, BD139 and BD140 gone, Zener diode 22v and 33V both supply rails died too (shorted). Any help will be appreciated. Thanks.
This happens...usually mistakes while assembling
You should now remove all transistors to check them outside the board as this save time if you're not skilled to measure them connected to the board...check if you have NPN in the place you should have a PNP...also f you have not assembled inverted...watch transistor datasheet to be sure about that.
Now you gonna have a hard time searching for mistakes...be patient and work slowly...if nervous, then stop and try once again in another day.
Check all parts...this happened before with many amplifiers...everybody makes mistakes...the one said have never failed is because never did nothing...we humans do these things daily.
I fell sorry about your trouble...i wish i could fly to your place to fix for you...but i cannot.... you know, i do think god decide not to alow me to be rich because i would spend all my money helping others.... in this moment i would be flying to your place....god realised i would spent too much money in audio too.
hehehe
Carlos
You should now remove all transistors to check them outside the board as this save time if you're not skilled to measure them connected to the board...check if you have NPN in the place you should have a PNP...also f you have not assembled inverted...watch transistor datasheet to be sure about that.
Now you gonna have a hard time searching for mistakes...be patient and work slowly...if nervous, then stop and try once again in another day.
Check all parts...this happened before with many amplifiers...everybody makes mistakes...the one said have never failed is because never did nothing...we humans do these things daily.
I fell sorry about your trouble...i wish i could fly to your place to fix for you...but i cannot.... you know, i do think god decide not to alow me to be rich because i would spend all my money helping others.... in this moment i would be flying to your place....god realised i would spent too much money in audio too.
hehehe
Carlos
Good evening all, hope you guys doing good.
Alas the Amp is working!
Too many human errors, Thanks Carlos 🙂.
But one more issue to fix, R16 is heating Up badly. I must lower my Supply Voltage i reckon. Above 60VDC rail to rail is not a good idea I must say. Please correct me if I'm wrong but I burned 4pcs BD139, 4pcs BD140 4pcs 22V and 4pcs 33V Zener diode using 69VDC (Plus and Minus rail) till I put a 100Ohm/10 watts then amp behaved rightfully. Rightfully that music came out from speaker and no burning trannies 🙂 but that R16 should cool down.
Please help me freshen up R16. Thanks in advance.
Alas the Amp is working!
Too many human errors, Thanks Carlos 🙂.
But one more issue to fix, R16 is heating Up badly. I must lower my Supply Voltage i reckon. Above 60VDC rail to rail is not a good idea I must say. Please correct me if I'm wrong but I burned 4pcs BD139, 4pcs BD140 4pcs 22V and 4pcs 33V Zener diode using 69VDC (Plus and Minus rail) till I put a 100Ohm/10 watts then amp behaved rightfully. Rightfully that music came out from speaker and no burning trannies 🙂 but that R16 should cool down.
Please help me freshen up R16. Thanks in advance.
R16 should be highest wattage you can fit in that position... I think I used a 5W in there with 70V rails.
Well guys.... ohms law say that we have 1.21 watts there.
maybe your 2 Watts resistance is too much hot because it may be not be a real 2 watts unit.... you know...fake unit...they say it is 2 watts when it is 1 watt.
Well...replace R16 by a 22K resistance and use 5 watts there..then you will have it cool....so..the idea is to increase the resistance value... 12K, 15K, 18K or 22K and to increase watts ratio to 5 watts.
regards,
Carlos
maybe your 2 Watts resistance is too much hot because it may be not be a real 2 watts unit.... you know...fake unit...they say it is 2 watts when it is 1 watt.
Well...replace R16 by a 22K resistance and use 5 watts there..then you will have it cool....so..the idea is to increase the resistance value... 12K, 15K, 18K or 22K and to increase watts ratio to 5 watts.
regards,
Carlos
Carlos I really thank you for an awesome AMP!
Now I feel like late Ric Segreto is singing in front of me, indeed a great amp, sound full of details and i clearly hear all instruments.
i will do a final touch and post some pics sooner.
Now I feel like late Ric Segreto is singing in front of me, indeed a great amp, sound full of details and i clearly hear all instruments.
i will do a final touch and post some pics sooner.
A 2W resistor dissipating 1.2W will at 25C ambient have a temperature of just over 60C.... VERY hot. A 5W will be only slightly cooler, but will be more reliable in the long term, and more capable of dealing with higher ambient temperature. Piggybacking two power resistors inparallel there will reduce the temperature alot.
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Thank you...i am glad you like it
Welcome to the Corporation...send me pictures to the hall of fame.
regards,
Carlos
Welcome to the Corporation...send me pictures to the hall of fame.
regards,
Carlos
How much current needs to flow through R16?
That is the important piece of design information. From there appropriate values of resistance and dissipation capability can be determined.
That is the important piece of design information. From there appropriate values of resistance and dissipation capability can be determined.
There's a group buy to MKIII-Hx folks
The second group buy...first one is still open and have collected 53 orders in 72 hours.
regards,
Carlos
The second group buy...first one is still open and have collected 53 orders in 72 hours.
regards,
Carlos
I have my Precision built with drivers, output transistors, and VBE multiplier on the same heatsink. The VBE multiplier is dead center, with the drivers on the sides, then follows the outputs, as per the PCB.
I had a quick question about this. Would it be better for me to take the drivers out and mount them on the top of the PCB with their own small heatsink? Such as this: (The heatsink currently resides on an LCD TV SMPS, but can be salvaged.) There are fins on the back, but they are horizontal, not vertical.
Also, I know it will be better if I move the VBE Multiplier transistor closer to an output transistor.
I had a quick question about this. Would it be better for me to take the drivers out and mount them on the top of the PCB with their own small heatsink? Such as this: (The heatsink currently resides on an LCD TV SMPS, but can be salvaged.) There are fins on the back, but they are horizontal, not vertical.
Also, I know it will be better if I move the VBE Multiplier transistor closer to an output transistor.
Attachments
If you are facing problems about heat...a better idea would be
Increase heatsinks size, install fan blowers and use your amplifier with higher impedance instead to make all these modifications.
This amplifier was tested... when using good heatsinks , "L" adaptor, thermal grease and large heatsinks i do not remember any thermal issues.
In other words dear Odissey.... why to do all these things you are saying?... are you facing troubles with your amplifier?
Carlos
Increase heatsinks size, install fan blowers and use your amplifier with higher impedance instead to make all these modifications.
This amplifier was tested... when using good heatsinks , "L" adaptor, thermal grease and large heatsinks i do not remember any thermal issues.
In other words dear Odissey.... why to do all these things you are saying?... are you facing troubles with your amplifier?
Carlos
No troubles Carlos. Just wondering.
Sooner or later I will get around to create an enclosure, and when I do I want the amplifier to be permanantly installed and finished with the best possible setup inside. I will make the neatest wiring, and optimize board placements (I will have other circuits inside). I do plan to use a fan inside, actually, although I haven't had any thermal issues. It is a big 200mm fan that will be on the bottom, blowing upwards. It is a 12V low noise fan, but I will try to run it around 9V instead for lower speed. It is not necessarily needed but should increase reliability. Never hurts for things to run a bit cool.
Also, from my experiments, I learned that, for me, the bias current effects the sound quality, and thus it would have a more consistently high sound quality if the bias current stayed as still as possible. I found that higher bias current than the "sweet spot" lowers the perceived sound quality.
As it is right now the amp can play at very loud - just below "pain" - levels, without reaching a too-high heatsink temperature, for long periods of time. But, at these levels, as the heatsink heats up, the bias increases just a bit - about 2mV over Re (6mA) - but never more.
When I was experimenting with bias I found that 15mV (45mA) over Re vs. 20mV reduced the sound quality a bit. The music was still clear and undistorted, of course, but it began to lack "romance", or that "liquid highs" aspect that I enjoy.
So, I guess my ultimate question is this: Will doing this increase bias stability to the point that it is worth it? Or will this, in your opinion, be a waste of time?
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