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Author Topic: I am looking for input on choice of building audio amplifier  (Read 2024 times)
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sphinx
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« on: March 16, 2024, 06:43:55 18:43 »

i know it might not be the place to ask for input on building an audio amplifier
i just didnt want to join some other forum for just this subject

i am looking for a fairly good not too simple in design

here are my sort of guide lines
this will be built with components from non alibaba or similar sellers
more like digikey mouser

300-500 euros/dollars

a good and solid design with a bit of reserve power and to be longish lasting
i want to build something together pre-amp but this is just for the power-amp
no displays or any mcu in this just as simple as is need to be not not like
modern amp with advanced displays, since this will be a 2-channel amp

100w in 8ohm

the semiconductors from readily available stock and not any abscure expensive ones
easy to find ones

low noise(nothing extreme the best i can for mentoined price)

good bandwith i think this not that difficult to achieve with modern components

with dc check realy and maybe some other protection thats good to have

i am not sure what more to ask for.

thanks in advance
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enzine
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« Reply #1 on: March 17, 2024, 06:37:37 18:37 »

In 1984 I built and used for many years the famous "Crescendo" amplifier published by Elektor in 1982.
Some of my friends still use it with great satisfaction.
Excellent sound, great dynamics, easily available components are just some of the advantages of this workhorse of homemade HiFi.
Recently (2001) Elektor published the "Crescendo Millenium Edition".
I recommend you start with this project.

https://www.elektormagazine.com/magazine/elektor-198212/44973

https://www.elektormagazine.com/magazine/elektor-200104/16985


Ciao
Enzo
« Last Edit: March 17, 2024, 06:50:05 18:50 by enzine » Logged
optikon
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« Reply #2 on: March 18, 2024, 12:42:05 00:42 »

Any reason buying one cannot work for you?
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sphinx
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« Reply #3 on: March 18, 2024, 02:04:12 02:04 »

i do not want anything without schematics

nothing with any mcu/firmware/displays

something that has a calculated lifespan built in

no obscure components that cant buy

no markings made by the manufacturers on components
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Sideshow Bob
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« Reply #4 on: March 18, 2024, 09:55:38 09:55 »

How will you attack this. Like will you go class D or a more traditional way class A/B. Linear or Switch Mode PSU? Another interesting topic may be the housing. As a power amplifiers are built around the heatsinks. Perhaps it could be an idea to source a non working 100W (ish) power amplifier locally. And use that as a base. Most likely the output stage will be blown. But the transformer will probably be OK(the transformer will be condiserable part of the total cost). It is just an idea and I do not know how viable this is for you. 
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sphinx
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« Reply #5 on: March 18, 2024, 12:00:00 12:00 »

i have two chassis i can use on the biggish side
i also have a big heatsink i could cut in 2 pieces
i will use a/b type amplifier
not yet sure about power supply

the onkyo Onkyo TX-SV 727 R i have got bad i will see if i can fix it and recap it, its the first time i got issues with it
it has not been fixed/repaierd before, if not i will build something

i very rarely went above 50% on the volume

just for fun i looked for the power transistor for the onkyo 2sc3281 and 2sa1302
i was looking to see prices for those and on alibaba 10 pairs for 60$ sounds a bit too low
and looking at the pictures i could seen they been sandblasted as the little dimples are also blasted as well

on ebay i saw some where they were dirty and not clean so there is something fishy going on

so no asia bying for me
« Last Edit: March 18, 2024, 12:53:00 12:53 by sphinx » Logged

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PM3295
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« Reply #6 on: March 18, 2024, 05:09:28 17:09 »


just for fun i looked for the power transistor for the onkyo 2sc3281 and 2sa1302
i was looking to see prices for those and on alibaba 10 pairs for 60$ sounds a bit too low
and looking at the pictures i could seen they been sandblasted as the little dimples are also blasted as well

on ebay i saw some where they were dirty and not clean so there is something fishy going on

so no asia bying for me

From my experience, most of the older or expensive power transistors from these budget sites are fake remarked parts.
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optikon
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« Reply #7 on: March 19, 2024, 01:25:43 01:25 »

You said you could spend $500 so I think it can be done for that, no need to buy from grey markets / e-pray

There are gobs of reference amplifiers (schematics) on the web, grab one, update it with your part choices, simulate it, then build it.

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Sideshow Bob
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« Reply #8 on: March 19, 2024, 11:35:04 11:35 »

In 1984 I built and used for many years the famous "Crescendo" amplifier published by Elektor in 1982.
Some of my friends still use it with great satisfaction.
Excellent sound, great dynamics, easily available components are just some of the advantages of this workhorse of homemade HiFi.
Recently (2001) Elektor published the "Crescendo Millenium Edition".
I recommend you start with this project.

https://www.elektormagazine.com/magazine/elektor-198212/44973

https://www.elektormagazine.com/magazine/elektor-200104/16985


Ciao
Enzo
The problem is that it may be difficult to source some components. I looked at the 2001 version and even here it hard to get most of the transistors. Like 2SK537, 2SK1530, 2SJ201
From what I have found.
2SK1530/2SJ201 ->IRFP240PBF/IRFP9240PBF
also
2SK537 -> 2SK1643/2SK1338/2SK2733 But non of these SKUs is available from mouser(or similar)
« Last Edit: March 20, 2024, 04:53:20 16:53 by Sideshow Bob » Logged

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kumar
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« Reply #9 on: March 19, 2024, 12:48:28 12:48 »

insted of the output mosfet,  2SK537 ,
2SK1530 ,i used BUZ901,BUZ906 without any issues
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« Reply #10 on: March 19, 2024, 02:49:07 14:49 »

The problem is that it may be difficult to source some components. I looked at the 2001 and even here it hard to get most of the transistors what. Like 2SK537, 2SK1530, 2SJ201
From what I have found.
2SK1530/2SJ201 ->IRFP240PBF/IRFP240PBF
also
2SK537 -> 2SK1643/2SK1338/2SK2733 But non of these SKUs is available from mouser(or similar)

You're right, I bought them from a well-known and reliable distributor of electronic components.
Only now have I realized that more than 10 years have passed   Shocked.

"Fugit irreparabile tempus"

Ciao
Enzo
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PM3295
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« Reply #11 on: March 19, 2024, 05:52:34 17:52 »

Try get hold of a copy of the book "Designing Audio Power Amplifiers 2019" by Bob Cordell. He walks you through a complete design, with the theory, calculations, simulations and measurements from the input through to the output stage. He starts with a basic design and goes through steps to lower the %THD, depending how complicated you want this to be. Years ago, having a %THD of 0.1% was considered to be Hi-Fi quality. Bob shows how you can lower this figure by many orders of magnitude by analyzing the parts responsible for causing distortion and how to improve it. It is a really good read. The parts he used in his designs should still be readily available.  

Alternatively you could also look for books on audio amplifier design by Douglas Self. Both are worth reading.
« Last Edit: March 19, 2024, 06:00:35 18:00 by PM3295 » Logged
sphinx
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« Reply #12 on: March 20, 2024, 01:10:01 01:10 »

a got the 2006 ed of the book mentioned and some other books
by Douglas Self. i wasn't exactly looking for designing myself
but i will check out the books i borrowed from the internet libraru.
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« Reply #13 on: March 20, 2024, 05:17:48 05:17 »

You can always just build up one of Bob's designs without doing any design yourself. You will have to make your own pcb design to suit your enclosure, panel layout, etc. The advantage will be having an in depth description of the circuit operation if you need to do some troubleshooting  after the build or later in use when something breaks down.   
« Last Edit: March 20, 2024, 05:25:08 05:25 by PM3295 » Logged
Sideshow Bob
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« Reply #14 on: March 20, 2024, 09:38:17 09:38 »

insted of the output mosfet,  2SK537 ,
2SK1530 ,i used BUZ901,BUZ906 without any issues
You meant did you not?
2SK1530= BUZ901 N Channel, 200 V, 8 A, 1.5 ohm
2SJ201= BUZ906 P Channel, 200 V, 8 A, 1.4 ohm
But what did you use for the  2SK537 N -Channel 1A mosfet?
« Last Edit: March 20, 2024, 11:23:26 11:23 by Sideshow Bob » Logged

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kumar
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« Reply #15 on: March 21, 2024, 02:50:03 02:50 »

You meant did you not?
2SK1530= BUZ901 N Channel, 200 V, 8 A, 1.5 ohm
2SJ201= BUZ906 P Channel, 200 V, 8 A, 1.4 ohm
But what did you use for the  2SK537 N -Channel 1A mosfet?
sllidshow Bob,what he said is obsolutely correct.BUZ901 and BUZ906 is used as output pair.
in 1982's Elektor crescendo article,1984's Elektor mini crescendo article they were not used  any transistor for quiescent current circuit.
but elektor crescendo millenium Edition, they used 2SK537 in quiescent current circuit.
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« Reply #16 on: March 21, 2024, 11:05:12 11:05 »

I discovered this Chinese manufacturer https://en.viva-elec.com.tw/stereo-2023.html

I designed a simple amplifier for myself, I plan to order production this month.



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« Reply #17 on: March 21, 2024, 12:44:54 12:44 »

I discovered this Chinese manufacturer https://en.viva-elec.com.tw/stereo-2023.html

I designed a simple amplifier for myself, I plan to order production this month.
Is it your design? Maybe what I would have done is do add holes for some for some machine screws to secure and ensure good contact with the IC and the heatsink.  It should be easy to a drill tap on the heatsink. To get the holes on the heatsink aligned. Just print out the PCB on paper in size 1:1 and use that as a template. Also if you use say 3mm machine screws use a slightly bigger hole say 4mm. And create a keepout era for copper around the holes
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« Reply #18 on: March 21, 2024, 06:07:22 18:07 »

I've thought about it, but I plan to just stick it on. I want to test how it performs.
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Sideshow Bob
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« Reply #19 on: March 21, 2024, 06:40:18 18:40 »

I've thought about it, but I plan to just stick it on. I want to test how it performs.
Just for testing you could use thermally conductive adhesive tape. But I suspect if they have a recommenced heat sink it will be somewhat undermentioned. Anyway how do you order these Ics? I have for a long time wanted to build a class D amplifier. Ics from Texas Instruments are available at many trusted component outlets   
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« Reply #20 on: March 21, 2024, 07:04:43 19:04 »




I order printed circuit boards and assembly completely from jlcpcb. I really like this option. I've done it many times, it always comes, I turn it on and everything works.
In December I made a development board for myself with MCU PIC18F47Q84







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« Reply #21 on: March 22, 2024, 12:04:23 12:04 »



I order printed circuit boards and assembly completely from jlcpcb. I really like this option. I've done it many times, it always comes, I turn it on and everything works.
In December I made a development board for myself with MCU PIC18F47Q84



How long did jlcpcb take for assembly?  I usually use PCBWay for bare boards, which have always been excellent.
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« Reply #22 on: March 22, 2024, 12:15:05 12:15 »


Assembly usually takes no more than 1-2 days.
This is the time from ordering the PCB itself to the moment of complete assembly.

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« Reply #23 on: March 23, 2024, 11:16:58 11:16 »

Assembly usually takes no more than 1-2 days.
This is the time from ordering the PCB itself to the moment of complete assembly.
Did you add some extra output filters etc, or did you just follow the Typical Application from the data sheet. Also it could be interesting to hear how it sounds
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« Reply #24 on: March 24, 2024, 08:17:02 08:17 »


In this project, I want to assemble according to the circuit offered by the manufacturer and test the audio amplifier chip itself.
I'm still making some changes to the project.

If you are interested, I can inform you how the process of ordering, manufacturing and testing an audio amplifier will go.

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