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HIFI power amp discussions
http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=6215
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Author:  Yungman [ 14 Sep 2018, 04:47 ]
Post subject:  Re: HIFI power amp discussions

I notice you use blank proto board to build your amp. You should consider laying out your own board. You can pack a lot more onto a pcb. I use surface mount components if all possible. The boards are packed as you can see the pictures of the pcb layout. More importantly, if you know how to layout, you can get bigger trace, less interference, less ground loops and signal loops.

There are free software out there. I sent to China to fab the boards. My boards are big, like 12" X 4". I order 2mm thick and 2oz copper, that's why it's expansive.

Author:  ILoveHiFi [ 15 Sep 2018, 15:03 ]
Post subject:  Re: HIFI power amp discussions

Yungman wrote:
I notice you use blank proto board to build your amp. You should consider laying out your own board. You can pack a lot more onto a pcb. I use surface mount components if all possible. The boards are packed as you can see the pictures of the pcb layout. More importantly, if you know how to layout, you can get bigger trace, less interference, less ground loops and signal loops.

There are free software out there. I sent to China to fab the boards. My boards are big, like 12" X 4". I order 2mm thick and 2oz copper, that's why it's expansive.


Actuall proper pcb is tons more time consuming, not to mention higly expensive in comparison.

It takes more time, usually takes me a day or two even three days if its a massive pcb.
I normally get my test schematics done within one whole working day, and if its big project then normally within two days I get something built and tested.

Protype boards always allow for me to reuse them and changing wiering could be easier.

Some more complex projects I have to use proper PCB, but the ones I try to design always aims to improve perfomance without increasing compent count much.
The 4 stage amp was to improve performance but also reduce component count as much as possible. I'm proud to design something with such low component count while mainting high perofmance.
Its impracticall to use hundreds of tranistors when you don't have a IC chip building machine and using through hole components only.

I don't have much SMD components and I don't have much exprience hand soldering them, but for prototyping its usually better to use through hole since you can easily cut leads and solder them on a few copper wires sticking out as quick replacements

Author:  Yungman [ 16 Sep 2018, 04:57 ]
Post subject:  Re: HIFI power amp discussions

I don't think you can build a big power amp the way you build. Too many components. Like I said, when go high power and large signal, circuit gets a whole lot more complicated. Also, I design as if it is for production, have all the protection circuits in it. You are not going to build the board in one day. I doubt you can build in 3 or 4 days.

What is your day job? EE? Nobody use through hole anymore. I use SMD whenever possible. It is easier to rework, easier to build if you use pcb. There are special technique and if you master it, it's a breeze. Too bad the OPS which is the high power part, you just cannot use SMD as you need the size for the power dissipation.

PCB is a lot more consistent, also signal integrity is a lot better. You try to build a power amp with 9 pairs of transistors on a breadboard, you see what I mean.

Also, you are going to have problem when you have to match the holes on the big heatsink. It's a different world between a big amp and a small amp.

If you send to China, it's not that expensive. Save you a lot of work.

Author:  ILoveHiFi [ 16 Sep 2018, 17:44 ]
Post subject:  Re: HIFI power amp discussions

I did build power amps out of prototype boards only.
The +-24v class a amp with 3 pairs of output transitors uses these

I was going to build a +-36v class a one but my dad is renting out the other half of the house and I get complaints since I like things loud on speakers so staying away from speakers at the moment.

I did get a prototuye pcb with holes on and already mounted 8 pairs of tip36c 35c on the two massive heat sinks,
total of 16 pairs of transitors and 4 pairs of lm317 will regulate the smps supply to +-32v.
I encountered some plorbems with my op amp gain stage so another reason for me to abandon the project for meantime.
The output stage is fully ready to go but just needs a proper gain stage and will be rock n roll.
This is like a year or a year and half ago.

I like speakers best.

I am currently a undergraduate electrical engineering student still studying. 1997

Also I am unexprinced with relays therefore I have brought quite a few relay boards from china with neat small 5w 9v ac supplys for it.

Also I do not plan to sell anything without a proper PCB, prototype pcb is only good for prototyping.

Author:  ILoveHiFi [ 17 Sep 2018, 00:07 ]
Post subject:  Re: HIFI power amp discussions

My dad did hifi projects since 15, he looked at books with valve schmeatics and he built them.
Without learning from my dad at younger ages I would not be talking about hifi today.

Author:  Yungman [ 17 Sep 2018, 05:09 ]
Post subject:  Re: HIFI power amp discussions

I was an EE and manager of EE for 30 years before I retired. My degree was actually Chemistry, but never work a day in the field. I started out modifying guitar amps as I was a lead guitarist and always chasing for the sound. I actually invented the power scaling in 1978 but I did not patent it as I was too young. Later London power came out with the same idea and they got it on the market.

I was so into electronics that I quit music and got into electronics. I never did any audio in my career. I designed all sort of electronics from front end of digital scope, IC, Ultrasound medical scaner, Mass spectrometers, SONET communication and even military projects. I just like to jump into all sort of different facet of electronics instead of concentrate my experience in one field. I published papers in America Institute of Physics Review of Scientific Instruments and own 2 patents.

After I retired, I still put a few years studying electromagnetics and advanced math. Then I went full circle and got back into guitar amp design. Designed two amp, got bored, now I am designing hifi amp for the last 3 years.

this is pure enjoyment, there's no money in hifi field. You can't even find job in this that easy. Even though I design to the highest standard, I have no plan to market any of it. I had my career already. This is just hobby.

All my guitar amps are tube amps, but I never design a tube hifi amp. I am not convinced that tube amps are better. My only experience in tube hifi amp is disappointing.

Author:  Yungman [ 19 Sep 2018, 04:58 ]
Post subject:  Re: HIFI power amp discussions

ILoveHiFi wrote:
I did build power amps out of prototype boards only.
The +-24v class a amp with 3 pairs of output transitors uses these

I was going to build a +-36v class a one but my dad is renting out the other half of the house and I get complaints since I like things loud on speakers so staying away from speakers at the moment.

I did get a prototuye pcb with holes on and already mounted 8 pairs of tip36c 35c on the two massive heat sinks,
total of 16 pairs of transitors and 4 pairs of lm317 will regulate the smps supply to +-32v.
I encountered some plorbems with my op amp gain stage so another reason for me to abandon the project for meantime.
The output stage is fully ready to go but just needs a proper gain stage and will be rock n roll.
This is like a year or a year and half ago.

I like speakers best.

I am currently a undergraduate electrical engineering student still studying. 1997

Also I am unexprinced with relays therefore I have brought quite a few relay boards from china with neat small 5w 9v ac supplys for it.

Also I do not plan to sell anything without a proper PCB, prototype pcb is only good for prototyping.


I like to see pictures of your big amp with big heatsink and all the power transistors.

Author:  ILoveHiFi [ 19 Sep 2018, 15:27 ]
Post subject:  Re: HIFI power amp discussions

viewtopic.php?f=10&t=1044&start=110

Author:  Yungman [ 19 Sep 2018, 16:41 ]
Post subject:  Re: HIFI power amp discussions

ILoveHiFi wrote:
http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=1044&start=110


Good, I was wondering how do you do it in a Tupperware.

I am for using SMPS, problem is I cannot find anything that fits. 24V is too low power, assume you swing +/-21V( 3V to rail), you get 1/2 X V^2/R = 27W max. That's too low. I need at least 30V. I even looked into Meanwell power supply that is 28V and it can be cranked to about 31V. BUT, it's too big to fit in the chassis. I did use it earlier on in a wood board proto amp.
Attachment:
SMPS supply.JPG


This is one with only 5 pairs of transistors with two 24V SMPS that are 10A each and cranked to 27V. It did at least as good as the Nakamichi PA-7. But as I said, it's too big to fit in a real amp chassis.

Also, remember, those SMPS are NOT designed to have 30,000uF hanging at the output, they oscillate. They are closed loop feedback inside, they always have an upper limit of how much capacitance it can drive. Without the cap, you can run into shutdown when you draw peak current.

I don't have experience designing SMPS, when I was working, I consider those are easy stuff and had my engineer designing SMPS and I designed the more challenging things. I regret this. I should have done it myself at least once. The off the shelf SMPS are not very good, too noisy, they don't know signal integrity. That's the reason people that work on high precision analog and low noise analog system avoid SMPS.

In the early 90s when I got promoted as manage of engineering, I pushed to switch all power supplies to SMPS. We reduced two rack mountful of analog supplies to just one small rack. We design very high precision and low noise electronics, I even have SMPS right in the heart of an electrometer amp that measure current down to pA. I used noise cancellation to get rid of the noise and it worked like a champ.

Audio power amp is nothing close to the sensitivity of the the Mass Spectrometers we design, SMPS will work perfect. Just have to know their limit. Know signal integrity design. I just need to learn the transformer part of it.

BTW, you run 2.5A/ch, that's way too low. You can run into shutdown. I remember they talked a lot about this problem in DIYAudio. I used at least 10A supply to give 5A per ch and still use a lot of caps to prevent current spike. that's when it gets too big.

Author:  ILoveHiFi [ 21 Sep 2018, 00:54 ]
Post subject:  Re: HIFI power amp discussions

2.5A results in about 58-60C in a 20C ambient
The SMPS is hot and the transistors are near thermal limit if you take into account of heat trasnfser limits

The amp swings +-2v to rails

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