Doug Self's book "Audio Power Amplifier Design Handbook" is excellent too, covering things you might not consider, such as the PCB layout and it's effect on distortion..
I borrowed that on an inter library loan a few years back. He made a humorous crack at Radio Shack in it. Good to get another perspective. His website is good too.
You may read Cyril Bateman's article called "Capacitor & Amplifier Distortions" (ELECTRONICS WORLD November 2003). Author showed why it's better to use non-polar or bi-polar capacitor in the negative feedback divider circuit rather than a polar cap with a diode.
Awesome. It's great to see you and the new project for 2023. The things I like best about your channel is your ability to innovate and motivate others into commenting on, and building, your projects; there has already been some great feedback and I appreciate your positive comments on the feedback. Your ability to stay focused on the original user case is admirable and you're not easily swayed, without good reason; but as always just because someone has an opinion it doesn't make it right! I'm learning but I don't feel that I have sufficient experience or confidence in my abilities to comment on the projects design aspects, not just yet. But I, my breadboard, parts bin and plastic await the evolved design so that I can learn while building this awesome project. I wish you and yours seasonal greetings and an innovative and prosperous new year. Iso guy
This looks very similar to my circuit! If the values are close enough it will sound very good and any cross over distortion will decrease with more output transistors. I have very different transistors other than the outputs that are the same and powering it with +-100v. Great videos!
Good to see you back in action It's wonderful that a new amplifier is coming up, Happy New Year to you Sir John It's wonderful to watch your videos ,❤️
Happy new year, John! I like your design very much. It is straight forward and very clear. The input path has a decoupling capacitor and a low pass filter. It is followed by the differential amplifier input stage with a current source from the positive voltage and a current mirror to the negative one. Maybe you can use the same type of current source as in your voltage amplification stage (Q6, Q7) because it has lower noise. A voltage breakdown device like a Zener diode is quite noisy. D6 in the feedback path ist very strange. I guess it should save the C4 from too much voltage against its polarization at low frequencies. I would prefer to limit the low frequency with the input coupling capacitor and increase C4 in a way, that you will never get more than a few 100 mV in the wrong direction. The voltage amplification stage is clear. There is a current source coming from the positive voltage. Its current passes through the Vbe multiplier Q8 (is it adjustable?) and goes across Q9 into negative voltage. C6 slows the voltage amplifier down to avoid oscillations. Strange is Q16. It forms with its resistors a kind of current limit. Is this intended? I mean, Q9 draws always only the current which is delivered by the current source from the top. What is this current limit for? It also reduces the voltage amplification of Q9. I would cast it out. The last section is the current amplification stage in Darlington emitter follower configuration. I would suggest to use a Sziklai configuration to get 3 Vpp more output voltage swing between the power rails and a bit more power out of the design. The Sziklai configuration is also thermally more stable than the Darlington configuration. Nevertheless it is wise to bring Q8 together with Q10 to Q15 on the heat sink for thermal regulation of the quiescent current. The reason for D4 and D5 is not clear to me.
Happy New Year and thanks for the input! Yes, some of the extra parts prevent additional failure due to OPS failure or unintentional operation. Q16 protects Q9 if an output transistor or driver fails and sends current back into the VAS. Q9 has no limit and will quickly burn. Q16 will limit current to ~30ma. By then a rail fuse should open. It is just a couple cheap parts for some protection. Sziklai has its benefits but as I understand, it doesn't work well with paralleled transistors. It is easier to go unstable and crossover distortion can't be minimized as well as with an EF stage. I do prefer it in lower power amps were getting output swing closer to the rails is more desirable.
@@JohnAudioTech thank you for your answer. The paralleled transistors may be the point with Sziklai. I have never tryed Sziklai with paralleled output transistors and a single driver transistor. My amplifier designs work mainly in the voltage range of low power op amps between +/- 12 to 18 V where paralleled output transistors or even driver transistors are not necessary. I've found that your output transistor combination D44VH10 / D45VH10 is very useful. They have a beta of more than 100 still at an Ic of 3 A. So you can drive them directly with an NE5532 or SA5532.
@@gkdresden Your voltage range is my preferred range for my personal listing amplifiers. My main system is 15w per channel and is plenty for me using 90 dB speakers. After seeing the Carver amps and some PA amps using opamp front ends, I've been thinking of designing something like that but lower power. The opamp would drive a push-pull VAS. Forgot to mention D4 and D5 in the JAT801 prevent reverse bias damage should one of the rails go open (e.g. open fuse). In some conditions, the open side can get pulled towards the opposite rail beyond its ground (0v) causing components to be reverse biased. It's a Cordell recommendation.
I use Magnat Vector 1 speakers (4 Ohm impedance) with 91 dB/W @ 1 m distance. 10 to 15 W is enough for my living room audio. Listening to music I usually do not exceed the class A operating range. The output power is in the order of several 100 mW with just a few peaks in the range of 1 or a few W. Bob Cordell has a lot of practical experiences with Murphys law for audio amplifiers. I never met the case that the positive rail went lower than ground potential, except you lose ground potential as well. But in this case it doesn't matter at all.
Happy New Year John! Thank you for all your efforts. I am patiently awaiting all of the parts to build a pair of JAT501’s. I have a 24V 500VA dual primary/dual secondary Hammond toroidal collecting dust that now has a purpose!!
John, the onsemi driver pairs, MJE15030/1 ithink, and MJE 15034/5 are pretty much the defacto standard in drivers for this type of amplifier. I've used both with excellent results. All I believe are readily available from suppliers.
Hi Mr john and happy new year! Your new power specs explain the changes that you did to the old design, the paralleled output stage, the higher current on the drivers and the vas stage. Can you give a bit more insite about the pi filters on the rail and the filtering that you did on the signal input and output? BTW, thanks for your series on audio amps. Really informative and helpful!!!
The filter helps to isolate the output stage from the earlier stages since the OPS can draw a lot of current and put noise on the rails. Not absolutely necessary but a good design. It is important to keep the filter resistors low enough not to cause a large voltage drop that may keep the VAS stage from swinging close to the rails since the OPS has no voltage gain. The input and output filters have been covered in other videos.
I don't know if you have seen but there is interesting thread on diyaudio forum discussing JAT501 and 801... Great series with these amplifiers btw. I actually learned a lot going through 501 playlist and it is fun to see all of separate amp stages built out from real parts. Too many people just have fun with sim and never get to actual builds lol You can add emitter follower to VAS - improves thd and removes some of the stress from the differential pair - can use 2ma to drive vas easily and makes LTP more stable. as it is, in the circuit, you have beta enhancement for LTP and for OPS but not for VAS btw. would make sense to add it to VAS too from that perspective. can also look into two pole compensation instead of simple miller cap - adding resistor and another cap is minimum parts for great results
Great to hear that there is enough interest in the design for upgrades. The original intent was to keep it rather simple but can certainly be improved.
Oh if only i was a youngster again 🤔 i loved building amps and music things John, but now days my left ear is 9khz my right about 11khz so hi fi makes no difference to me 🤣 thanks for the interesting channel bro 👍🏴🙏🇺🇦
Dear John, thrilled to see the continuation of the JAT familly amps, i was wondering have you considered maybe to separate voltage for the output pair of transistors, and add higher voltage for them only, i think that this amp should get quite a few watts, without changing the other parts or modify this excellent schematic drastically. What do you think?
Hi John just curious on your thoughts on quasi complimentary designs. It may be a little bit easier for transistor selection but you may have an opinion on the quality of the outcome.
Nice topology John but strongly reminds me APEX AX-14 amplifier on "diyaudio" but in contrast to him, YOU explain in details everything & THAT IS WHAT I'M STRONGLY APPRECIATE. B U T , do we need for domestic Hi-End usage 150 W / 8 Ohm ? I know that the "humble" 1 pair FJP5200/FJP1943 at 35-0-35 V are giving plenty of power (or maybe some other ONsem audio pairs in TO-220)
I imagine they all have similarities until they get into exotic designs. I don't need 150w. My listening amp is only 15w but it's something to design and make videos for.
Good day sir I just want to ask way your not using a cascode VAS or in differential input, is using cascode design is not getting more noise or having stability issue?
New Project. Really looking forward to the series, John! Are there any equivalents for the MJE15032/33? I can't seem to get them in my favourite store.
I have a list of suitable transistors in my little notebook that seems to be MIA at the moment. I'll have to see what is in stock and not tagged "obsolete".
the other day i was also reading Douglas Self's Audio Power Amplifier Design book, and he mentioned a gain boosting darlington arrangement at Q9 in the final design. i thought that would be a cool thing to bring out detailing in the music too. what is your opinion on this ?
Pay him and he'll tell you that you can have it if you can build it but you probably can't. Buy him better gear but don't be offended when he makes videos finding faults with it hahahaha. He needs to take into consideration he should appreciate his fans more and sound like he's got a gun to his head every other video. Sorry man. Watch his video history. He's talented, very talented I respect that but not him.
@JJ74Q Formerly Jailbreak I wasn't trying to troll man but he answered me all the time when I was patron or thanked him. I got soured when I very respectfully said I had to stop being his patron because I literally had hurricane tear off my roof. Hurricane Fiona. His answers about stuff when asking for help are very negative. I'm a hobbyist and was at the point of what I wanted to concentrate on more after you get to a certain point as a hobbyist you can be ok at alot of things but never a master at anything. I've been playing guitar and teaching when I find a student who will stick with it and I do it for free. I'm the anti youtube I think. I donate alot of money and tons of stem related items to various charities. I don't advertise it but I'll take any student and buy them an acoustic with the stipulation that they have to practice even if they only want enough lessons to get going. I don't hoard guitars either and I give them to people who want to play but can't. I keep a box full of t12 soldering stations, dmms and practice kits to give away. All anyone needs to do is ask. But I have the same stipulation. I'm not trying to toot my horn but I saved up 1000cad to get a new scope which by happenstance Jat was given and I ordered a brymen bm786 eevblog model as a pick me up after the hurricane. I wanted the 121gw but I like to split my money as I don't want to be short something if someone who needs it asks. This guy gets a 121gw and makes an ass of himself tearing it apart in some sort of exposee and yeah he got that for free too. I've seen him do it with other gear his whiny voice paid for. I'm not going to link any videos they aren't hard to find. It's not jealousy either. I have better gear than him. Email me for proof. Gear don't mean shit if you can't use it though. I respect the knowledge but not the man. Sorry for rambling, I have trouble getting my point across
Do ya need anything brother? Pcb built, 500 dollar digikey card, a 400 dollar multimeter that pulls a couplr milliamps in standby? I can get ya a new scope and awg if ya want brother. Or would you find reasons to complain about all these things while others who can't afford them scratch their heads. I had so much respect for you man.
Doug Self's book "Audio Power Amplifier Design Handbook" is excellent too, covering things you might not consider, such as the PCB layout and it's effect on distortion..
I borrowed that on an inter library loan a few years back. He made a humorous crack at Radio Shack in it. Good to get another perspective. His website is good too.
That and his "Small Signal Audio Design" are both great reads.
You may read Cyril Bateman's article called "Capacitor & Amplifier Distortions" (ELECTRONICS WORLD November 2003). Author showed why it's better to use non-polar or bi-polar capacitor in the negative feedback divider circuit rather than a polar cap with a diode.
Awesome.
It's great to see you and the new project for 2023.
The things I like best about your channel is your ability to innovate and motivate others into commenting on, and building, your projects; there has already been some great feedback and I appreciate your positive comments on the feedback.
Your ability to stay focused on the original user case is admirable and you're not easily swayed, without good reason; but as always just because someone has an opinion it doesn't make it right!
I'm learning but I don't feel that I have sufficient experience or confidence in my abilities to comment on the projects design aspects, not just yet.
But I, my breadboard, parts bin and plastic await the evolved design so that I can learn while building this awesome project.
I wish you and yours seasonal greetings and an innovative and prosperous new year.
Iso guy
Thanks Isoguy! Electronics is constant learning process but so is life.
MJE15032G/33G is readily available. Also in the differential or VAS have you looked at KSA992/ksc1845 and KSA1381/KSC3503
I very excited for this series. The Jat501 amp series is a CZcams treasure… some of the greatest amplifier info out there.
10:12
Dear sir John
Looks like a got perfect Toroidal Transformer with 36-0 ,36-0, 39-0 & 39-0 Windings for your JAT801 Project.
Good to see people building their own amps from scratch!
Thanks for video. HappyNewYear back. ,,👍
This looks very similar to my circuit! If the values are close enough it will sound very good and any cross over distortion will decrease with more output transistors. I have very different transistors other than the outputs that are the same and powering it with +-100v.
Great videos!
Happy New Year John. Looking forward to your newest project, sounds fun
Good to see you back in action
It's wonderful that a new amplifier is coming up,
Happy New Year to you Sir John
It's wonderful to watch your videos ,❤️
Happy new year, John! I like your design very much. It is straight forward and very clear. The input path has a decoupling capacitor and a low pass filter.
It is followed by the differential amplifier input stage with a current source from the positive voltage and a current mirror to the negative one. Maybe you can use the same type of current source as in your voltage amplification stage (Q6, Q7) because it has lower noise. A voltage breakdown device like a Zener diode is quite noisy. D6 in the feedback path ist very strange. I guess it should save the C4 from too much voltage against its polarization at low frequencies. I would prefer to limit the low frequency with the input coupling capacitor and increase C4 in a way, that you will never get more than a few 100 mV in the wrong direction.
The voltage amplification stage is clear. There is a current source coming from the positive voltage. Its current passes through the Vbe multiplier Q8 (is it adjustable?) and goes across Q9 into negative voltage. C6 slows the voltage amplifier down to avoid oscillations. Strange is Q16. It forms with its resistors a kind of current limit. Is this intended? I mean, Q9 draws always only the current which is delivered by the current source from the top. What is this current limit for? It also reduces the voltage amplification of Q9. I would cast it out.
The last section is the current amplification stage in Darlington emitter follower configuration. I would suggest to use a Sziklai configuration to get 3 Vpp more output voltage swing between the power rails and a bit more power out of the design. The Sziklai configuration is also thermally more stable than the Darlington configuration. Nevertheless it is wise to bring Q8 together with Q10 to Q15 on the heat sink for thermal regulation of the quiescent current. The reason for D4 and D5 is not clear to me.
Happy New Year and thanks for the input!
Yes, some of the extra parts prevent additional failure due to OPS failure or unintentional operation. Q16 protects Q9 if an output transistor or driver fails and sends current back into the VAS. Q9 has no limit and will quickly burn. Q16 will limit current to ~30ma. By then a rail fuse should open. It is just a couple cheap parts for some protection.
Sziklai has its benefits but as I understand, it doesn't work well with paralleled transistors. It is easier to go unstable and crossover distortion can't be minimized as well as with an EF stage. I do prefer it in lower power amps were getting output swing closer to the rails is more desirable.
@@JohnAudioTech thank you for your answer. The paralleled transistors may be the point with Sziklai. I have never tryed Sziklai with paralleled output transistors and a single driver transistor.
My amplifier designs work mainly in the voltage range of low power op amps between +/- 12 to 18 V where paralleled output transistors or even driver transistors are not necessary.
I've found that your output transistor combination D44VH10 / D45VH10 is very useful. They have a beta of more than 100 still at an Ic of 3 A. So you can drive them directly with an NE5532 or SA5532.
@@gkdresden Your voltage range is my preferred range for my personal listing amplifiers. My main system is 15w per channel and is plenty for me using 90 dB speakers. After seeing the Carver amps and some PA amps using opamp front ends, I've been thinking of designing something like that but lower power. The opamp would drive a push-pull VAS.
Forgot to mention D4 and D5 in the JAT801 prevent reverse bias damage should one of the rails go open (e.g. open fuse). In some conditions, the open side can get pulled towards the opposite rail beyond its ground (0v) causing components to be reverse biased. It's a Cordell recommendation.
I use Magnat Vector 1 speakers (4 Ohm impedance) with 91 dB/W @ 1 m distance. 10 to 15 W is enough for my living room audio. Listening to music I usually do not exceed the class A operating range. The output power is in the order of several 100 mW with just a few peaks in the range of 1 or a few W.
Bob Cordell has a lot of practical experiences with Murphys law for audio amplifiers. I never met the case that the positive rail went lower than ground potential, except you lose ground potential as well. But in this case it doesn't matter at all.
Happy New year John, looking forward very much to your New projects, great stuff sir.
Happy New Year John! Thank you for all your efforts. I am patiently awaiting all of the parts to build a pair of JAT501’s. I have a 24V 500VA dual primary/dual secondary Hammond toroidal collecting dust that now has a purpose!!
Happy new year John, waiting for next installment...
John, the onsemi driver pairs, MJE15030/1 ithink, and MJE 15034/5 are pretty much the defacto standard in drivers for this type of amplifier. I've used both with excellent results. All I believe are readily available from suppliers.
I'll add those to my list if they're not already on it.
......also, look at MPSA18 for the longtail pair. I've become fond of Sanken outputs. Really like how they sound.
Happy new year and keep designing..
Looking forward to this!! The jat 501 series really helped me understand how the various stages of a power amp work!
Happy New Year to you as well!
Hi Mr john and happy new year! Your new power specs explain the changes that you did to the old design, the paralleled output stage, the higher current on the drivers and the vas stage. Can you give a bit more insite about the pi filters on the rail and the filtering that you did on the signal input and output?
BTW, thanks for your series on audio amps. Really informative and helpful!!!
The filter helps to isolate the output stage from the earlier stages since the OPS can draw a lot of current and put noise on the rails. Not absolutely necessary but a good design. It is important to keep the filter resistors low enough not to cause a large voltage drop that may keep the VAS stage from swinging close to the rails since the OPS has no voltage gain. The input and output filters have been covered in other videos.
@@JohnAudioTech thanks for the reply! Looking forward for the next videos!!
I don't know if you have seen but there is interesting thread on diyaudio forum discussing JAT501 and 801... Great series with these amplifiers btw. I actually learned a lot going through 501 playlist and it is fun to see all of separate amp stages built out from real parts. Too many people just have fun with sim and never get to actual builds lol
You can add emitter follower to VAS - improves thd and removes some of the stress from the differential pair - can use 2ma to drive vas easily and makes LTP more stable.
as it is, in the circuit, you have beta enhancement for LTP and for OPS but not for VAS btw. would make sense to add it to VAS too from that perspective.
can also look into two pole compensation instead of simple miller cap - adding resistor and another cap is minimum parts for great results
Great to hear that there is enough interest in the design for upgrades. The original intent was to keep it rather simple but can certainly be improved.
Happy New Year !
Looking fwd to this project John. I hope boards will be available
can you make current feedback amp project too?
Oh if only i was a youngster again 🤔 i loved building amps and music things John, but now days my left ear is 9khz my right about 11khz so hi fi makes no difference to me 🤣 thanks for the interesting channel bro 👍🏴🙏🇺🇦
Awesome!
Dear John, thrilled to see the continuation of the JAT familly amps, i was wondering have you considered maybe to separate voltage for the output pair of transistors, and add higher voltage for them only, i think that this amp should get quite a few watts, without changing the other parts or modify this excellent schematic drastically. What do you think?
Nice!
9:30 P = Vrms^2/Z => Vrms^2 = PZ => Vrms = √(PZ). Vp = √2 Vrms = √2 x√(PZ) = √(2PZ); yep happy with that.
Thanks!
Happy new year John. Looking forward to see the progress on this one.
Good jobs
Hi John just curious on your thoughts on quasi complimentary designs. It may be a little bit easier for transistor selection but you may have an opinion on the quality of the outcome.
Looks a lot like mine less the VI protection and the active bias.
John design something around 1000 watt for field use
This is as far as I'm going with power. I'd look to class D for such high power.
@@JohnAudioTech but class D has more distirtion as higher frequency. And the design is so complicated
Nice topology John but strongly reminds me APEX AX-14 amplifier on "diyaudio" but in contrast to him, YOU explain in details everything & THAT IS WHAT I'M STRONGLY APPRECIATE.
B U T , do we need for domestic Hi-End usage 150 W / 8 Ohm ? I know that the "humble" 1 pair FJP5200/FJP1943 at 35-0-35 V are giving plenty of power (or maybe some other ONsem audio pairs in TO-220)
I imagine they all have similarities until they get into exotic designs.
I don't need 150w. My listening amp is only 15w but it's something to design and make videos for.
Good day sir I just want to ask way your not using a cascode VAS or in differential input, is using cascode design is not getting more noise or having stability issue?
They are not necessary for the distortion performance I'm after. Adding the extra parts always raises the concern of stability.
New Project. Really looking forward to the series, John!
Are there any equivalents for the MJE15032/33? I can't seem to get them in my favourite store.
I have a list of suitable transistors in my little notebook that seems to be MIA at the moment. I'll have to see what is in stock and not tagged "obsolete".
@@JohnAudioTech Thanks for spending the time, John.
Any benefit of people doing a zobel for their speakers? Make their speakers a much simpler load/lineae
Any chance the JAT-801 will be finished soon ? I built the JAT-501 and it came out pretty nice. Looking forward to building the JAT-801
Who knows with me! I take my time. I do have a bit of redesign work to do with it and tests. I'd hope later this year.
the other day i was also reading Douglas Self's Audio Power Amplifier Design book, and he mentioned a gain boosting darlington arrangement at Q9 in the final design.
i thought that would be a cool thing to bring out detailing in the music too.
what is your opinion on this ?
A noob question- why not a opamp -instead of long tailed pair ????
Please stop using 2SA1943/2SC5200. Can you go with MJ21193/4
What about NJW1302//NJW3281?
Also can we move the zobel to the binding posts
LED or diode better for biasing in constant current source?
Where can I buy the 501?
Pay him and he'll tell you that you can have it if you can build it but you probably can't. Buy him better gear but don't be offended when he makes videos finding faults with it hahahaha. He needs to take into consideration he should appreciate his fans more and sound like he's got a gun to his head every other video. Sorry man. Watch his video history. He's talented, very talented I respect that but not him.
@@jstro-hobbytech I respect your opinion. Matter of fact I think I’ve been watching for at least a year and not a single ❤️ 🤔
@JJ74Q Formerly Jailbreak I wasn't trying to troll man but he answered me all the time when I was patron or thanked him. I got soured when I very respectfully said I had to stop being his patron because I literally had hurricane tear off my roof. Hurricane Fiona. His answers about stuff when asking for help are very negative. I'm a hobbyist and was at the point of what I wanted to concentrate on more after you get to a certain point as a hobbyist you can be ok at alot of things but never a master at anything. I've been playing guitar and teaching when I find a student who will stick with it and I do it for free. I'm the anti youtube I think. I donate alot of money and tons of stem related items to various charities. I don't advertise it but I'll take any student and buy them an acoustic with the stipulation that they have to practice even if they only want enough lessons to get going. I don't hoard guitars either and I give them to people who want to play but can't. I keep a box full of t12 soldering stations, dmms and practice kits to give away. All anyone needs to do is ask. But I have the same stipulation. I'm not trying to toot my horn but I saved up 1000cad to get a new scope which by happenstance Jat was given and I ordered a brymen bm786 eevblog model as a pick me up after the hurricane. I wanted the 121gw but I like to split my money as I don't want to be short something if someone who needs it asks. This guy gets a 121gw and makes an ass of himself tearing it apart in some sort of exposee and yeah he got that for free too. I've seen him do it with other gear his whiny voice paid for. I'm not going to link any videos they aren't hard to find. It's not jealousy either. I have better gear than him. Email me for proof. Gear don't mean shit if you can't use it though. I respect the knowledge but not the man. Sorry for rambling, I have trouble getting my point across
Do ya need anything brother? Pcb built, 500 dollar digikey card, a 400 dollar multimeter that pulls a couplr milliamps in standby? I can get ya a new scope and awg if ya want brother. Or would you find reasons to complain about all these things while others who can't afford them scratch their heads. I had so much respect for you man.
What are you talking about? Are you sure you are commenting on the right channel? I have never heard John complain about anything, 'brother'.
@None well said brother. I said my piece. They were observations brother backed up by facts brother. Peace brother!
@None can't believe I missed this comment brother. You literally made by day bry brother broskie