wrt to first quote: I am glad you like my coil building skills, and the coil measured fine. The resistor has been inserted thru the coil by many builders with no problems. The coil can be mounted on top of the resistor if desired, I found that the springy magnetic wire was hard to work with in a vertical position, so I laid it horizontal.
wrt to second quote: I respect your knowledge and idea's with regards to the changes that you have proposed and posted in the above post's. I am a beginner and have been learning from the designers of this circuit and use their recommendations to build a fine amp. Hugh Dean has quoted in his numerous threads that this design does not measure well but sounds very good. I can easily mount Q3 on my heatsink, I just have to desolder from the pcb and move to the heatsink and connect flying leads to the pcb. But why do this extra work if the transistor does not require it ?
Thank you for your posts, it generates healthy and unique conversation's, I hope other's chime in. 🙂
MM
I have not yet met radio amateurs who like curved parts, well, ok.
Pay less attention to freaky radio masters, there should not be any elements inside the coil...
Why are you doing me a favor?
you yourself will understand the features of the installation, it is best to measure the temperature of the substrate with the device and calculate the temperature of the crystal and compare it with the temperature according to the datasheet...
It's a delusion. there are significant differences between the phrase "may work" and "normal operating mode".
I don't quite understand why you have so much fun? you never said with what initial current your quasi-complementary output stage curve works ... This is if you consider that this value is limited by the lower biprolar transistor. Frick's opinion that it "may work" we do not take into account ...
The next significant issue is that your input transistor does not amplify anything, more precisely, its gain is -13dB in the entire audio frequency band, i.e. it is essentially a parasitic element. The challenge is how you are going to fix it. or again you will rely on the freak opinion - it works "and so it will do" ...
Do you want to have a high-quality apparatus or exercise "how not to do"?
HK, it is a working circuit, built by many as is, I do not have to fix anything. I will not be baited by the likes of you. You need to relax, maybe more ☕ , maybe more 
. If you don't lighten up 
will not be good to you this year.
Over and out👎
. If you don't lighten up will not be good to you this year.Over and out👎
HK instead of ranting your untested and unproven opinions on a tried and tested amp which many love to listen to, move over from sims, build one stock amp and another as per your mods, measure (if possible), listen and then report.
On the contrary, what you are engaging with is unhelpful to say the least.
On the contrary, what you are engaging with is unhelpful to say the least.
From my experience, average TO-126 transistor dissipating 250mW will run anywhere between 30 - 45 degrees C, which is perfectly normal operating mode.
Exactly.
These things are not based on delusion but science. They can be easily calculated from the information that is provided by the manufacturer.
Let's look at Q5, which in my case is the MJE350:
Rth (j-a) is 100 degrees per Watt
So 250mW gives a junction temperature of 50 degrees C:
((100*0.25)+25) = 50 degrees (C)
The absolute maximum power dissipation PD at 25 degrees ambient is 1.25W:
((100*1.25)+25) = 150 degrees (C)
which is the maximum case temperature allowed, so it is possible (although unwise) to run the MJE350 up to 125 degrees (C).
HK, if you want to learn how these things work rather than make vague incorrect statements, then have a look at this article about how to calculate thermal values: ROHM Guide to Junction Temperatures as a start.
These things are not based on delusion but science. They can be easily calculated from the information that is provided by the manufacturer.
Let's look at Q5, which in my case is the MJE350:
Rth (j-a) is 100 degrees per Watt
So 250mW gives a junction temperature of 50 degrees C:
((100*0.25)+25) = 50 degrees (C)
The absolute maximum power dissipation PD at 25 degrees ambient is 1.25W:
((100*1.25)+25) = 150 degrees (C)
which is the maximum case temperature allowed, so it is possible (although unwise) to run the MJE350 up to 125 degrees (C).
HK, if you want to learn how these things work rather than make vague incorrect statements, then have a look at this article about how to calculate thermal values: ROHM Guide to Junction Temperatures as a start.
this is not a very successful scheme, or a scheme of a loser, there are errors - they need to be corrected, because you can get higher quality.
of course, you don't even know how much initial current the output stage needs to operate in linear mode - shame...
Samuel Jayaraj
move away from stereotypes, especially about those whom you do not know and who are on the forum under a pseudonym. You will not be able to convict me that I do not manufacture power amplifiers in a practical version - I have been manufacturing them since 1984 ...Focus on correcting the author's circuit - or are you not understanding the circuit and not understanding the topology?
you argue from the position that you have almost the only transistor in the universe, but what about the temperature gradient of the board, the heat dissipation of power transistors and the closed case? you would get a cuff from me for such assumptions, especially since the use of modes over 60% of the maximum takes the active element out of the linear mode. It's very stupid to argue just on principle because you think it's better that way. Can you practice numbers? Or do you also think that the input transistor with a gain of -13dB is not a problem?
HK,
What is your notion of performance of an audio amplifier? Is it THD?
Since you say you are very experienced, and know the art well, how about giving us your benefit of your skill and redesign the amplifier for 'superior performance' - and perhaps also a Bode-Nyquist plot as well so we can see it is stable.
HD
What is your notion of performance of an audio amplifier? Is it THD?
Since you say you are very experienced, and know the art well, how about giving us your benefit of your skill and redesign the amplifier for 'superior performance' - and perhaps also a Bode-Nyquist plot as well so we can see it is stable.
HD
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Are you missing the information already posted? do you understand simulation results? or will you know everything by the details?
This was not an answer to you and not for you, so don't be a secretary...
why are you acting so stupid? above, I asked specific questions with specific meanings, what do you not understand? Why doesn't the input transistor amplify anything? don't you want to think for yourself?
Hk,
Please read the forum rules. this is not your thread. start your own thread to discuss your points. Don't argue with the designer . first you learn about a humble gentleman AKSA. Don't be rude and harsh. you can discuss and question only in a polite way.
Please read the forum rules. this is not your thread. start your own thread to discuss your points. Don't argue with the designer . first you learn about a humble gentleman AKSA. Don't be rude and harsh. you can discuss and question only in a polite way.
@Hennady Kovalsky
In this (as in other threads) you seem determined to criticise and question without offering any worked advice or practical technical input from yourself. Perhaps you should do as others have suggested and put forward a corrected and modified version that can be put under the same kind of scrutiny as you so seem to like inflicting upon others.
The general tone of your comments both here and elsewhere on the forum does you no favours and crosses the line on what is acceptable.
Hi X and other builders. I got some time to diy. My heatsinks are a bit small for the quasi pcb, so I am going with flying leads. I have managed to fit a small BD139 to one of xrk's BJT helper boards. Question:
In the pic below, can I solder my leads as shown by the arrows to the large pads on the helper board, or, do I have to solder to the pads inside the white box. If soldered inside the white box, please indicate lead positions. I have tried to follow traces/tracks, but just getting confused, so looking for some advice. I have also a single pic in hopes that you can follow tracks/traces. Thanks.
In the pic below, can I solder my leads as shown by the arrows to the large pads on the helper board, or, do I have to solder to the pads inside the white box. If soldered inside the white box, please indicate lead positions. I have tried to follow traces/tracks, but just getting confused, so looking for some advice. I have also a single pic in hopes that you can follow tracks/traces. Thanks.
Hi Myles,
It’s been a while since I looked at that helper board. All I can say is to use a DMM continuity meter to check which pin goes where. It looks about right but best to verify with the audible beep of a continuity meter.
It’s been a while since I looked at that helper board. All I can say is to use a DMM continuity meter to check which pin goes where. It looks about right but best to verify with the audible beep of a continuity meter.