Hi,
I'm considering building this amp: DIY 5 Watt Class-A Audio Amplifier Circuit Behaves Valve Amp | Electronic and Techno
But I can't find the BD439 transistors, so my question to you guys is, would it work with BD441 or BD442?
By the way, have anyone tried this amp? how does it sound? I know it's cheap, so I'm not expecting it to be a miracle. I've only built a gainclone TDA2050 before, can it be compared to that one?
Cheers
I'm considering building this amp: DIY 5 Watt Class-A Audio Amplifier Circuit Behaves Valve Amp | Electronic and Techno
But I can't find the BD439 transistors, so my question to you guys is, would it work with BD441 or BD442?
By the way, have anyone tried this amp? how does it sound? I know it's cheap, so I'm not expecting it to be a miracle. I've only built a gainclone TDA2050 before, can it be compared to that one?
Cheers
I have built both..and the TDA2030 sounded better
I suppose the TDA2050 would sound the same as the TDA2030...but really i have never assembled the TDA2050.
This amplifier needed modifications to operate with other transistors, different than he ones suggested.... i do not remember exaclty, as this happened long time ago, but i remember was not very good and gave me some bad time to put the one to operate.
The sound resulted not very good when i have finished...was dismounted alike other thousands i have assembled by curiosity to listen...the ethernal search for a miracle amplifier....and i continue to do that....i have not find the perfect one.
All them have qualities and all them have weak points.
I do not suggest you to assemble..keep you TDA2050 because, for sure, you will be more happy this way.
I will not feed this thread... chip amplifiers is another forum..so... this post is the first and the last.... of course the amplifier you asked is solid state, discrete and transistorized, but the option is a chip amplifier.
Read our forum a little bit more, there are several better options than this amplifier...take some time to read and to know people and designs we have into this forum and also into the Chip amplifiers forum, also Nelson Pass.... study first (compare, judge, ballance,select, weigth, think about and decide latter, for sure will not be this one you have posted)....then, after that study, you will decide (better) what to be assembled.
Will be interesting if you have the kindness to complete your profile, informing your country for instance... it is nice to make a presentation about you, we like to know forum friends.
regards,
Carlos
I suppose the TDA2050 would sound the same as the TDA2030...but really i have never assembled the TDA2050.
This amplifier needed modifications to operate with other transistors, different than he ones suggested.... i do not remember exaclty, as this happened long time ago, but i remember was not very good and gave me some bad time to put the one to operate.
The sound resulted not very good when i have finished...was dismounted alike other thousands i have assembled by curiosity to listen...the ethernal search for a miracle amplifier....and i continue to do that....i have not find the perfect one.
All them have qualities and all them have weak points.
I do not suggest you to assemble..keep you TDA2050 because, for sure, you will be more happy this way.
I will not feed this thread... chip amplifiers is another forum..so... this post is the first and the last.... of course the amplifier you asked is solid state, discrete and transistorized, but the option is a chip amplifier.
Read our forum a little bit more, there are several better options than this amplifier...take some time to read and to know people and designs we have into this forum and also into the Chip amplifiers forum, also Nelson Pass.... study first (compare, judge, ballance,select, weigth, think about and decide latter, for sure will not be this one you have posted)....then, after that study, you will decide (better) what to be assembled.
Will be interesting if you have the kindness to complete your profile, informing your country for instance... it is nice to make a presentation about you, we like to know forum friends.
regards,
Carlos
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The circuit is attempting to dynamic bias Q2.
I think R8 and R9 would have to be hand selected for different gain variations in Q2.
This type of circuit is sensitive to power supply quality too. Pehaps you should look at the Zen v4 from Nelson Pass. It has a proberly designed dynamic bias, and a supply regulator. The N-channel FETs may be any type you can obtain locally, Q3 may be any small signal NPN device.
http://passdiy.com/pdf/zen-v4.pdf
I think R8 and R9 would have to be hand selected for different gain variations in Q2.
This type of circuit is sensitive to power supply quality too. Pehaps you should look at the Zen v4 from Nelson Pass. It has a proberly designed dynamic bias, and a supply regulator. The N-channel FETs may be any type you can obtain locally, Q3 may be any small signal NPN device.
http://passdiy.com/pdf/zen-v4.pdf
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I agree with what Carlos said.
And he's being very modest - he has a nice design worth looking at called the DX amplifier. Greg's Web Site
Also look here: ESP Projects Pages - DIY Audio and Electronics
Olof - a name from the North, from cold places ?
p.s. for the Class A amplifiers:http://www.tcaas.btinternet.co.uk/index.htm
and also: http://www.passdiy.com/articles.htm
These will keep you busy, lots of very useful stuff.
And he's being very modest - he has a nice design worth looking at called the DX amplifier. Greg's Web Site
Also look here: ESP Projects Pages - DIY Audio and Electronics
Olof - a name from the North, from cold places ?
p.s. for the Class A amplifiers:http://www.tcaas.btinternet.co.uk/index.htm
and also: http://www.passdiy.com/articles.htm
These will keep you busy, lots of very useful stuff.
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JLH's 1969 amp is almost as simple (4 transistors), and probably a lot better. Details here: The Class-A Amplifier Site
I liked a lot this one:
DIY Class-A 2SK1058 MOSFET Amplifier Project
The biggest problem is the power supply, you'll need plenty capacitors. As I wasn't able to get rid of the hum completely, I built a capacitance multiplier at the cost of another heatsink.
DIY Class-A 2SK1058 MOSFET Amplifier Project
The biggest problem is the power supply, you'll need plenty capacitors. As I wasn't able to get rid of the hum completely, I built a capacitance multiplier at the cost of another heatsink.
Hey Ratza,
That amp will not give you over 1W at 10% THD. But you can easily rebuild it to a Zen V.1 to get proper function at the expense of lower sensitivity and Zin. With a CCS on top as in the Zen you will also get a lot better PSRR.
Raher than the original circuit in post #1 you may as well try something like this which is infinitely better and no more complex,
The Class-A Amplifier Site
First item... the JLH amp
The Class-A Amplifier Site
First item... the JLH amp
First of all, thank you very much for all answers. I've looked into all of the links and apparently the transistors aren't able to get at my local electronic store (https://www1.elfa.se/elfa~eu_en/b2b/catalogstart.do?tab=catalog).
Anyway, I found another circuit on the web: Cheap 100 to 150 Watt Amp . It seems really easy and cheap to build, so I think it would suit me perfectly.
Is there anyone that has tried this one? or how do you think it will perform?
Thanks,
Olof (Yupp, south. Sweden.)
Anyway, I found another circuit on the web: Cheap 100 to 150 Watt Amp . It seems really easy and cheap to build, so I think it would suit me perfectly.
Is there anyone that has tried this one? or how do you think it will perform?
Thanks,
Olof (Yupp, south. Sweden.)
Hi Olof
That's quite a change in direction; from a low-power class-A to a 100W class-B. I'm guessing your main requirement is something simple and easy to build?
In that case, the 100W one looks perfect. Performance won't be great but there's a few changes you could add on later to much improve it.
Simple construction on a piece of stripboard is ideal - then you can try out changes added on "rat's nest" style, and make it pretty later when you're happy with the performance. If you make it too beautiful the first time, you won't want to change it
Be careful with the transistor voltage ratings, though.
The output devices (TIP142, TIP147) are fine.
The input transistors will operate at about 45 V though, and should be changed from BC558 to BC556 or at least BC557.
First choice - BC556B. Second choice BC557B or BC557C. (The 'B' and 'C' are selected for higher current gain - nice, but not essential)
Here's the maximum voltage ratings for this range of transistors:
bc556 80V
bc557 50V
bc558 30V
The 'TIP41' should be a TIP41C as it needs to withstand up to about 90V.
Here's the maximum voltage ratings for that range of transistors:
tip41 40V
tip41A 60V
tip41B 80V
tip41C 100V
Cheers - Godfrey
That's quite a change in direction; from a low-power class-A to a 100W class-B. I'm guessing your main requirement is something simple and easy to build?
In that case, the 100W one looks perfect. Performance won't be great but there's a few changes you could add on later to much improve it.
Simple construction on a piece of stripboard is ideal - then you can try out changes added on "rat's nest" style, and make it pretty later when you're happy with the performance. If you make it too beautiful the first time, you won't want to change it
Be careful with the transistor voltage ratings, though.
The output devices (TIP142, TIP147) are fine.
The input transistors will operate at about 45 V though, and should be changed from BC558 to BC556 or at least BC557.
First choice - BC556B. Second choice BC557B or BC557C. (The 'B' and 'C' are selected for higher current gain - nice, but not essential)
Here's the maximum voltage ratings for this range of transistors:
bc556 80V
bc557 50V
bc558 30V
The 'TIP41' should be a TIP41C as it needs to withstand up to about 90V.
Here's the maximum voltage ratings for that range of transistors:
tip41 40V
tip41A 60V
tip41B 80V
tip41C 100V
Cheers - Godfrey
Hi again
A couple of details that were missing from the article:
1) The output transistors should be mounted on a decent-sized heatsink, but must be insulated from it (e.g. with mica washers and thermal grease).
2) The wires connecting the output transistors to the circuit board should be as short as possible (for high-frequency stability).
3) It's a good idea to add some power-supply decoupling capacitors (also for high-frequency stability). Something like 100uF electrolytic and / or 100nF ceramic for both supply rails. These need to be on the circuit board.
Cheers - Godfrey
A couple of details that were missing from the article:
1) The output transistors should be mounted on a decent-sized heatsink, but must be insulated from it (e.g. with mica washers and thermal grease).
2) The wires connecting the output transistors to the circuit board should be as short as possible (for high-frequency stability).
3) It's a good idea to add some power-supply decoupling capacitors (also for high-frequency stability). Something like 100uF electrolytic and / or 100nF ceramic for both supply rails. These need to be on the circuit board.
Cheers - Godfrey
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