The problem, I surmise, is that the member in question has about the same level of technical expertise as many of the newbies. Despite having been at it longer. If he/she would take the time and trouble to learn some of the science behind it, he would realize just how preposterous some of the things he/she proposes actually are.
Well, it just left your educational, experience and theoretical frame. Nothing more.
You always make the mistake of making audio untested statements. If you want to show that you do "science": first test, then answer;-)
Physics too: Everything and everyone takes the path of least resistance;-)
You always make the mistake of making audio untested statements. If you want to show that you do "science": first test, then answer;-)
Physics too: Everything and everyone takes the path of least resistance;-)
Before anyone starts cutting up their transistors, maybe you could tell first what would be the benefit ? does it sound better? Have you done a blind test?
You have to take the test. Blind or not;-)
Aside: you don't want to fall victim to any "expectation bias"-)
Aside: you don't want to fall victim to any "expectation bias"-)
That is what a blind test is for.
I will have to accept if you are not willing to share your listening experience, but can you tell me if there is information about this technique elsewhere?
The transistor will run a few degrees hotter, maybe tens of degrees if you really eff it up. At low current (ie, the part of the curve where most of the music and the critical crossover region occur) the gain and fT go UP. It falls faster at high current, though. And will overheat sooner. In these simplistic one transistor things that mr cumbb puts together it is possible to hear a difference - I’m sure it can be measured. It does NOT mean that it is good for it!!!!!! Or that cutting it is root cause. The increase in temperature IS.
Increase in operating temperature might also serve to explain his preference for TO-126 over TO-220 or TO-247.
Increase in operating temperature might also serve to explain his preference for TO-126 over TO-220 or TO-247.
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No. You have to do it. No one can make experiences for you or interpret them for you. And no one will be able to take them away from you;-)
Aside: a blind test is no guarantee of scientific validity. Non-scientifically educated people demand a blind test across the board because they do not know under what conditions it is useful and under what conditions it is not.
You are again only guessing, and again only showing your practical inexperience and also your audio electronics inexperience)-;
Do and measure what you are able to measure;-)
I never mentioned scientific validity. Please explain why a blind test would not be useful in this case, if that is what you are saying.
I am just asking some simple questions. I believe forums like this are about sharing, not trolling.
diy audio!
This is a forum for audio and for doing it yourself. So if I ask you to do it yourself in order to gain experience that we can then discuss. This forum is unfortunately occupied by audio and diy deniers who, when it comes to audio and doing, only troll and sabotage - instead to do, to test, to proof by listening, hearing: by audio)-;
You haven't heard or read anything about this "cut" method. As I am probably the first time, and the only, all you can do is test it;-)
That's how I do it: I test everything I don't know. And I test electronic parts and assemblies and functional groups. So I'm not one of those who claim to have been making audio electronics for decades but don't even know that amps, or even transistors, sound different, for example, or that bias controls have an influence on the sound, or claim that any change in sound is "subjective". Anyone who tests a lot by hearing knows that there is no "subjective" and no need for blind tests. Hearing too is a method to measure. And when it comes to audio, the "first" observation for which there is currently no equivalent;-)
So do, and then we'll talk about both the conceivable cause of a change you may have heard and about methods and blinding.
This is a forum for audio and for doing it yourself. So if I ask you to do it yourself in order to gain experience that we can then discuss. This forum is unfortunately occupied by audio and diy deniers who, when it comes to audio and doing, only troll and sabotage - instead to do, to test, to proof by listening, hearing: by audio)-;
You haven't heard or read anything about this "cut" method. As I am probably the first time, and the only, all you can do is test it;-)
That's how I do it: I test everything I don't know. And I test electronic parts and assemblies and functional groups. So I'm not one of those who claim to have been making audio electronics for decades but don't even know that amps, or even transistors, sound different, for example, or that bias controls have an influence on the sound, or claim that any change in sound is "subjective". Anyone who tests a lot by hearing knows that there is no "subjective" and no need for blind tests. Hearing too is a method to measure. And when it comes to audio, the "first" observation for which there is currently no equivalent;-)
So do, and then we'll talk about both the conceivable cause of a change you may have heard and about methods and blinding.
1. All transistors need a bipolar drive to the base, i.e. a pull-off resistor is not optional. Without any reverse base current, the transistor will take a long time to discharge, turn off, resulting in shoot through AB current spikes and slew distortion.
2. The only problem with transistor packages might be that TO-18, TO-39 are probably older devices with poorer performance. Perhaps transistor linearity could be called "sonic quality", but use of such language really means zero technical understanding.
3. The Wilson current mirror is not a good choice. You should use a constant current source, independent of supply voltage and more efficient use of parts, or perhaps a bootstrap.
4. TIP41, TIP42 are ft~=3MHz; too slow for use as drivers. This aggravates stability, feedback compensation problems.
5. R6, R7 in the collectors are useless unless the driver emitters are connected to them, as in lineup's circuit. The point is to buck the EB voltage to thermal stabilize the bias.
6. To make a successful amplifier, you need to understand feedback phase margin. Throwing capacitors into your circuit is shooting in the dark.
2. The only problem with transistor packages might be that TO-18, TO-39 are probably older devices with poorer performance. Perhaps transistor linearity could be called "sonic quality", but use of such language really means zero technical understanding.
3. The Wilson current mirror is not a good choice. You should use a constant current source, independent of supply voltage and more efficient use of parts, or perhaps a bootstrap.
4. TIP41, TIP42 are ft~=3MHz; too slow for use as drivers. This aggravates stability, feedback compensation problems.
5. R6, R7 in the collectors are useless unless the driver emitters are connected to them, as in lineup's circuit. The point is to buck the EB voltage to thermal stabilize the bias.
6. To make a successful amplifier, you need to understand feedback phase margin. Throwing capacitors into your circuit is shooting in the dark.
Guessing my @$$. Anything that compromises the thermal interface raises the semi’s junction temperature. I have measured this quite reliably both amateur-wise and professionally. ANY CHANGE in device characteristics is more reasonably explained by temperature change than by any magic pixie dust in the lead frame that is let out by sawing it.
It seems to me your main motive for posting here is to tell other people what to do.
Thanks to everyone who gave his/hers contribution to this project. The final modification is now ready, with elements borrowed from Lineup's design.
Having had the amplifier up and running for some days, I am very satisfied with the overall result. The amp seems to be stable and the sound quality is, for lack of a better word, flawless.
The schematic:
Although the breadboard version works well, I would like to have a more permanent solution, so here goes my first attempt in PCB designing. I found EasyEDA surprisingly simple to use for a total newbie, this is a result of three hours of work.
The PCB:
Having had the amplifier up and running for some days, I am very satisfied with the overall result. The amp seems to be stable and the sound quality is, for lack of a better word, flawless.
The schematic:
Although the breadboard version works well, I would like to have a more permanent solution, so here goes my first attempt in PCB designing. I found EasyEDA surprisingly simple to use for a total newbie, this is a result of three hours of work.
The PCB:
It's alive!
The PCBs have arrived and having soldered one channel ready, here are my findings:
There is an issue with oscillations:
Could it be something with my bench supply?
The sound is very good, even better in comparison to the protoboard version...
The PCBs have arrived and having soldered one channel ready, here are my findings:
There is an issue with oscillations:
- when using 8 ohm 5 watts resistor as a dummy load, everything works fine.
- when I connect an 8 ohm speaker as a load, the circuit oscillates on low push pull quiescent current settings (less than 50 mA). Mostly on higher output volume and on bass notes.
- however, when I add a capacitor with reasonable uF (such as 1000 uF or larger) between + and - rails, as shown in the picture below, the oscillations go away and everything works again perfectly, with even more "oomph" to bass.
Could it be something with my bench supply?
The sound is very good, even better in comparison to the protoboard version...
Precisely, this was the issue here, I will order new PCBs with some additional minor updates (proper ground plane, a bit wider tracks, correct footprints for TO-92 packages - a bit wider pad spacing, etc).
Does this look familiar?
https://drive.google.com/file/d/1-XFeJT29o3Rvy68revtMouLXOtFAe3No/view?usp=drive_link
https://drive.google.com/file/d/1-XFeJT29o3Rvy68revtMouLXOtFAe3No/view?usp=drive_link