100 watt audio amplifier

[kibet85]

http://english.cxem.net/amplifier/amplifier25.php

Hi all,has anyone done this amplifier....

[sakis]

from a company called smart kit electronics

if you buy the kit its almost for sure that it will not work since its using bdv 66-67 darligtons that they are not "selected" and i dont mean matched i mean selected ....

bdv 66-67 might have diferent behaviour between company to company and also between the same company but in diferent orders ...

so if in this amplifier you have P and N transitor that they are not complementary your amp is out of balance and bias ( very critikal for this design ) will never work properly

also 100w is overestimated and will never be produced as operating these bdv 66-67 in 40 volts rails and 4 ohms loads is way out of transitors can handle .....

one option will be to get the schematic and part list of this and operate it with MJ15015-16 very nice devices from on semi

but finally you dont expect much of it sound wise no matter what transistors you use

and the best option will be to built a DX amplifier from Destroyer x
( you will get a lot of forum help if you choose to do that ) or other designs the same simple but more safe and effective to built that are discussed here in the forum

simular to DX is the P3 or P3A from rod elliot or sixtec amplifier or symasym and so on ...

search .....you will find plenty

[lineup]

if looking at the circuit
there is nothing new about it
there is no improvement and good ideas, apart from very rudimentary circuit

It is, in my opinion, a very standard and simple version of Douglas Self blameless amplifier.
And if you want to build one,
I really recommend better you use the information from D. Self website here:

# 0: Introduction.
# 1: The Generic Amplifier Configuration.
# 2: The Eight Distortions.
# 3: Three Non-existent Distortions.
# 4: Techniques for Amplifier Investigation.
# 5: The Distortion Mechanisms.
# 6: The Concept of the Blameless Amplifier.
# 7: Conclusions.
# References.

http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm

[sakis]

the circuit that you are posting looks very nice but in the schematic is normal output transitors

in this particular kit the outs are darligtons BDV 66-67 OR BDW 83-84....

am i missing something ????

[lineup]

Originally posted by sakis

in this particular kit the outs are darligtons BDV 66-67 OR BDW 83-84....
am i missing something ????

the schematic is the very one from topic starter kit!!!!
see link in first post


Now, what output transistors to use, is many choices'

if going darlington we can consider some motorola devices
http://www.onsemi.com/PowerSolutions...s&category=798
Motorola = OnSemi

But the basic circuit is better from D.Self website
http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm
This is my basic message to the topic poster.
And good advice.

regards to friend sakis of Grekland = Greece = Hellas = Ella = The Sun
http://en.wikipedia.org/wiki/Hellen

Hellen (Ancient Greek: Ἕλλην, Hellèn)

The word comes from the prefix ??- (el- "sun, bright, shiny", (èlios, "sun")) + ??? (las "rock, stone").

[Andy L. Francis]

Originally posted by kibet85
http://english.cxem.net/amplifier/amplifier25.php

Hi all,has anyone done this amplifier....

The schematic looks OK.
Conventional Lin-topology solid-state class B/AB amplifier with darlington output stage, with overcurrent & short circuit protection.

The OP stage looks a bit undersized, but for home usage with the inbuilt protection it seems enough.
However for PA usage I'd add one more pair of OP devices. Or change these BDW devices to a 200...250W rated darlington pair.

R2 must be 0.47r/5W, I'm sure that 1r/2W is a misprint.

Solder a resistor in series with P1 for safety reasons! Then I'd double C6 to 220uF.
Rail fuses are needed, use 5A fast-blow fuses /rail.

With the mentioned modifications it's a reliable and cheap project. IMHO it's not that bad as Sakis and Lineup noted. It has a correct PCB design too!

[lineup]

Originally posted by Andy L. Francis

The schematic looks OK.
--------------
With the mentioned modifications it's a reliable and cheap project. IMHO it's not that bad as Sakis and Lineup noted.
It has a correct PCB design too!

Where did I say it was bad, Andy?
please show me the line of my statement

I just said that that the original of D.Self may be worth a look at ....

hehe .. sometimes people make up more than I say

[Andy L. Francis]

Some more comments...

P3A hasn't got public PCB design.
P3A hasn't got shortcircuit/overcurrent protection.
DX-amp hasn't got shortcircuit/overcurrent protection.
Symasym hasn't got shortcircuit/overcurrent protection.

Anyway I'm not sure that Kibet85 could find the driver/OP devices in Kenya for DX-amp/Symasym - however this project uses only cheap and easily available parts.

[lineup]

and the kit in question has got what, Andy?

[Andy L. Francis]

Originally posted by lineup


Where did I say it was bad, Andy?
please show me the line of my statement

I just said that that the original of D.Self may be worth a look at ....

hehe .. sometimes people make up more than I say

OMG! I need a coffee.
Awfully sorry!!!