This looks fun and once you have it finalized I’ll plan on building a stereo pair. Luckily I have enough parts on hand to build 50-60 channels, I’m limited by the number of 2SC5200s and 2SA1943s, last I counted I only had like 58 of each on hand. That and the power supplies, being the transformers and I’d have to pick up more larger caps for the mains filtering. That being said it would be very cool seeing a high power version made up. Something in the 250-500 watt at 8 ohms region. Even 200 at 8R would be cool. I just finished a repair on a pair of McIntosh MC501 monoblocks (500w output) and they use the same 2SC5200 and 2SA1943 for the outputs. Obviously way more of them.
Pardon me, but who needs 500W ? In a modern apartment even 35W of CLEAN POWER is more than adequate. Don't forget that many of us are living in apartment buildings next to not very tolerant (anything "correct" or conservative) neighbors of the exactly next door apartment.
My 4ohm bass drives in bass reflex actually are more like 2ohm minimum, when it's load is considered as reactive load with the phase swing, especially around tuning point. Also, the amp distortions increase tenfold as soon as the impedance starts to go 'crazy' below 100Hz.
Thank you so much sir, has been waiting for this test video,👍 is there any require to joint together the diffrencial stage transistor for thermally tracking? Or just leave it as it is.
16:06 isn't that due to the microphonic effect? The vibrations from tapping on it are affecting the quartz crystal reference frequency in the generator it is a piezoelectric device after all.
Hey John, Ive watched a ton of your videos, and they have really helped me get into DIY Audio, after watching your series of tests on small amplifier boards, I bought a bunch of little tda3116D2 boards, DSP boards, Dayton audio and Tang band speakers etc... I'm wanting to explore with a little more power, but noticed there seems to be a missing gap between these small 50w amplifier boards you can buy for a few dollars, and professional amplifier boards that cost hundred of dollars to get into the 100-200 watt range. Can you help me understand why that is?
Good question. A lot of these high power boards are rated at 4 or 2 ohms and are less at 8 ohms. Some are not telling the truth on actual power. You can estimate by the supply voltage used.
@@JohnAudioTech yes, your video on the tda3116d2 showing it's clean 50watt output was very helpful, so that's what I run them at now, so what's the difference between these little chip amplifier boards and larger pro amps that are in the few hundred watts range? Are the Larger amps not based off chips, but more hardy electronic components that can handle the power?
Hi John.Great video series. I have enjoyed every second of it. I'm just wondering about the measured HF bandwidth of 210Khz. The miller compensation value is shown as 100pF in the schematic. When I run the spice simulation I get a cut off of 65khz. Did you perhaps lower the value during testing to somewhere around 15-18pF?
@@JohnAudioTech Hi John, input base current into the input stage Q2 is 6,5 uA. The current provided to the differential pair provided by the current source is 3,3mA.
@@stephanminnie1418 IPS CCS should be 2.5ma, though higher should not harm the speed. An early design of the amp had the IPS current at 1.2ma and slew rate suffered. Also check the input filter cap value is not set too high. Should be 220 pf. Where did you get the schematic to model from? If it was from early in the video series on the amp, those are not fit for duty.
@@JohnAudioTech Hi John, I used the schematic in this video. Input filter cap is set at 220p. I have changed the CCS to 2,5 mA but the bandwidth remains the same with high cut-off at 65Khz. I emailed you the Spice file I used. Not sure what I am doing wrong. Thanks for the quick response.
-3dB BW is actually coming from RF when the power go to 50% , for audiophile amplifier it is better to say phase , and 0.5 dB BW . How much phase change you have at 20KHz ?? Phase margin and gain margin ?
Fantastic work, forgive my lack of knowledge on this question, It looks like your using electrolytic caps on the amp board, is there any advantage if you change the caps to a higher quality cap. Great work it looks like the amp measures really well. Keep up the great work.
Two of the caps are for supply bypassing. One is in the feedback loop. Using a better cap there can help but measured distortion is so low that the change in audibility is questionable.
@@JohnAudioTech thanks for the answer, I would love to study this more but time is something that is given to everyone except myself, one day I will, that's why I love you channel, I am living my amp design life through you, keep it up your info is fantastic. 👍
What about damping factor, John? We should create a new standard for that, say Df at 70Hz, because we need a good damping at low frequencies. Do you know why the official test is at 1000Hz?
During the design phase, I tested the DF at different frequencies. I was not able to measure it using the scope which means it is at least 1000. 1KHz is a common test frequency as it is near the middle of the audio spectrum (at least looking at it logarithmically) and it is where hearing is becoming the most sensitive.
John - Thank you for the great video series on this amp. I have decided to build this amp. I have already ordered boards. My first questions regard transistor matching. I have a PEAK Atlas DCA75. Will the hfe measurements from this device be good enough? How closely should the hfe's match?
Thanks for watching! hfe is fine for the small signal transistors. You should find they match to within a couple points. I wouldn't worry about the outputs because you'd have to buy a bunch to match. Just get the O grade ones.
What is the vbias setting is ?. What is the Hfe clasification on the 2N5551 and 2N5401is ?. Can I use 2SC1815 and 2SA1015 instead of 2N5551 and 2N5401 ?. Great video put together.
I measured it during the design phase of the project. I found it was too low and had to increase the current in the input stage in order to drive the VAS for improved slew rate.
Congratulations! A great project, and thanks a lot for taking us along your journey in such an educational way!
This series is inspiration for all who are trying to make their own amp.
Looking good John!
YESSSS!!!! HOLY HEAT SINK BATMAN!!! As always thank you John!!!
Greetings John. Very good job indeed.
Good video John, nice looking board ! Looks like we have the same bench psu & scope :)
Great Work 👍😍
This looks fun and once you have it finalized I’ll plan on building a stereo pair. Luckily I have enough parts on hand to build 50-60 channels, I’m limited by the number of 2SC5200s and 2SA1943s, last I counted I only had like 58 of each on hand. That and the power supplies, being the transformers and I’d have to pick up more larger caps for the mains filtering. That being said it would be very cool seeing a high power version made up. Something in the 250-500 watt at 8 ohms region. Even 200 at 8R would be cool. I just finished a repair on a pair of McIntosh MC501 monoblocks (500w output) and they use the same 2SC5200 and 2SA1943 for the outputs. Obviously way more of them.
Pardon me, but who needs 500W ? In a modern apartment even 35W of CLEAN POWER is more than adequate. Don't forget that many of us are living in apartment buildings next to not very tolerant (anything "correct" or conservative) neighbors of the exactly next door apartment.
My 4ohm bass drives in bass reflex actually are more like 2ohm minimum, when it's load is considered as reactive load with the phase swing, especially around tuning point. Also, the amp distortions increase tenfold as soon as the impedance starts to go 'crazy' below 100Hz.
Thank you so much sir, has been waiting for this test video,👍 is there any require to joint together the diffrencial stage transistor for thermally tracking? Or just leave it as it is.
I didn't see any need to join them in my tests. You still can if you want.
You can use forced air cooling using NOCTUA fans if you want to go that way.
16:06 isn't that due to the microphonic effect? The vibrations from tapping on it are affecting the quartz crystal reference frequency in the generator it is a piezoelectric device after all.
Hey John, Ive watched a ton of your videos, and they have really helped me get into DIY Audio, after watching your series of tests on small amplifier boards, I bought a bunch of little tda3116D2 boards, DSP boards, Dayton audio and Tang band speakers etc...
I'm wanting to explore with a little more power, but noticed there seems to be a missing gap between these small 50w amplifier boards you can buy for a few dollars, and professional amplifier boards that cost hundred of dollars to get into the 100-200 watt range.
Can you help me understand why that is?
Good question. A lot of these high power boards are rated at 4 or 2 ohms and are less at 8 ohms. Some are not telling the truth on actual power. You can estimate by the supply voltage used.
@@JohnAudioTech yes, your video on the tda3116d2 showing it's clean 50watt output was very helpful, so that's what I run them at now, so what's the difference between these little chip amplifier boards and larger pro amps that are in the few hundred watts range? Are the Larger amps not based off chips, but more hardy electronic components that can handle the power?
@@sportbikeguy9875 Some may be based on discrete output devices driven by a controlling IC. There are some high power ICs as well.
Hi John.Great video series. I have enjoyed every second of it. I'm just wondering about the measured HF bandwidth of 210Khz. The miller compensation value is shown as 100pF in the schematic. When I run the spice simulation I get a cut off of 65khz. Did you perhaps lower the value during testing to somewhere around 15-18pF?
No, it is 100pf. What is the current in the input stage of the sim?
@@JohnAudioTech Hi John, input base current into the input stage Q2 is 6,5 uA. The current provided to the differential pair provided by the current source is 3,3mA.
@@stephanminnie1418 IPS CCS should be 2.5ma, though higher should not harm the speed. An early design of the amp had the IPS current at 1.2ma and slew rate suffered. Also check the input filter cap value is not set too high. Should be 220 pf.
Where did you get the schematic to model from? If it was from early in the video series on the amp, those are not fit for duty.
@@JohnAudioTech Hi John, I used the schematic in this video. Input filter cap is set at 220p. I have changed the CCS to 2,5 mA but the bandwidth remains the same with high cut-off at 65Khz. I emailed you the Spice file I used. Not sure what I am doing wrong. Thanks for the quick response.
-3dB BW is actually coming from RF when the power go to 50% , for audiophile amplifier it is better to say phase , and 0.5 dB BW . How much phase change you have at 20KHz ??
Phase margin and gain margin ?
Thank you. I am hoping for Someone could make a build video :)
Niceeee
Love that bad boy.
Fantastic work, forgive my lack of knowledge on this question, It looks like your using electrolytic caps on the amp board, is there any advantage if you change the caps to a higher quality cap.
Great work it looks like the amp measures really well.
Keep up the great work.
Two of the caps are for supply bypassing. One is in the feedback loop. Using a better cap there can help but measured distortion is so low that the change in audibility is questionable.
@@JohnAudioTech thanks for the answer, I would love to study this more but time is something that is given to everyone except myself, one day I will, that's why I love you channel, I am living my amp design life through you, keep it up your info is fantastic. 👍
What about damping factor, John? We should create a new standard for that, say Df at 70Hz, because we need a good damping at low frequencies. Do you know why the official test is at 1000Hz?
During the design phase, I tested the DF at different frequencies. I was not able to measure it using the scope which means it is at least 1000. 1KHz is a common test frequency as it is near the middle of the audio spectrum (at least looking at it logarithmically) and it is where hearing is becoming the most sensitive.
Where can i find schematic for your amp?
Its available on my Patreon page in one of the posts I made a while ago.
Watch the video, i saw it.
Awesome stuff
John - Thank you for the great video series on this amp. I have decided to build this amp. I have already ordered boards. My first questions regard transistor matching. I have a PEAK Atlas DCA75. Will the hfe measurements from this device be good enough? How closely should the hfe's match?
Thanks for watching! hfe is fine for the small signal transistors. You should find they match to within a couple points. I wouldn't worry about the outputs because you'd have to buy a bunch to match. Just get the O grade ones.
What is the vbias setting is ?.
What is the Hfe clasification on the 2N5551 and 2N5401is ?.
Can I use 2SC1815 and 2SA1015 instead of 2N5551 and 2N5401 ?.
Great video put together.
Would it be difficult to add a clipping LED? That’s something I’d fancy on mine.
That is something that could be added to an outboard circuit.
@@JohnAudioTech that would be great if it’s not too much trouble to come up with a circuit diagram. Could be a good video?
Rototwibulator! Exactly right. 😉
Will you measure THD at different signal levels?
ceramic MLCC capacitors in signal generator might be sensitive to vibration...
"That's no moon. It's a sink station."
I've found a number of links about this amp, but none of them indicate why it is anything special. What makes it apparently so popular?
You didn't talk about slew rate of this amp .
I measured it during the design phase of the project. I found it was too low and had to increase the current in the input stage in order to drive the VAS for improved slew rate.
Hello sir,Please answer this question.Thank you
WHAT IS THE PURPOSE OF TRIMMER IN YOUR AMP SIR
THANK YOU VERY MUCH
Sets output bias current.
@@JohnAudioTech thank you very much sir
You deserve a million subs
Keep up the good works
❤️ From the Philippines
👍
is it anyway to buy a pair of this amplifiers as a kit ? Do you plan something like that (shipped to Europe) ? If yes I will send you an e-mail
No Snickers?
Snickers is in heaven 😞
Put your multimeter in mv range to measure millivolt.