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Old 17th November 2008, 08:05 PM   #51
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Default i ve been trying to follow

this thread but it wasnt really easy since i am quiet busy fixing some swedish mistakes ( he he he ) i welcome swedish mechanics to talk about this in private .....

gaborbela.......
i like this amp very much since i like very much simple circuits id like though to point just a couple of things

the first and most importand this is not a circuit to be done by any user since this importand information is missing (which actually i ve been screaming for 4 years now ) all amplifiers made with TIP 142 147.... bdv 66-67 bdw 83 84 and so on suffer from the """matching issue """" and eventually will fail if caution is not considered about this .....

and i dont mean the matching of transistors as we usually mean it .......but to know how the darligton is internally made and especially between the driver transistor and the output transistor ....

Meaning that depending on the order between tip 142 and tip 147 you may find serious diference on the way they work if the litle numbers down under the tip 142 and 147 are not explained so for shure and even worst it will never work properly if your tip 147 is from ST and your tip 142 is philips .....

in amplifier i made i had to use on semis mj 11015-16 just to be on the safe side ( transitors worked fine my amlifier was a joke )

so darligtons ..... no way hose !!!!!

it would be very nice if one of us used similar topology for the input and drive mosfet instead .....

........another thing that is very interesting is that many sugested use of four darligtons per board .....well i havent found any schematic in the past that might work with four darligtons ....but may be iam wrong .....

i am very excited by that cause if you use MJ11015-16 that is a 120 volt ....30A 200W or even more with MJ 11032-33 that will go to amazing 50A!!!!!! and 300w....

with a simple circuit to drive and four pairs of these outs you could easilly produce arround 200W @8R .....and almost double @4 ohms

any ideas ????? am i missing something here ????....


its been amazing all these years to watch people design and redesign amps in search of quality ,,badwidth,, slew rate BUT !!!! I would troully enjoy a permanent thread called """cheap power amps """" were afew transistors a big psu could produce a hell of a lot of power with bellow average quality .....belive me there is use for that too....

thanks people ........
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Old 17th November 2008, 09:41 PM   #52
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Default Sorry there is a mistake in the schematic

Hello
The lay out is not difficult at all but still need some experience to design it . I have no Eagle and I never ever used a PC board design software .
To replace the Darlingtons after my Experience that not not an easy point especially if you wish to keep the same sound quality .
Now when someone design the layout It would be better to go with two par output transistors .
That brought me a lot of life and improved the bass and the dynamic of the amp .
ATT.
THERE IS A MISTAKE ON THE SCHEMATIC the input resistor not2.2R is 2.2K .another think you can use a bit larger 2 or 4.7 uF capacitor on the input . But that is really matter of taste . How you like it .

Greetings
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Old 17th November 2008, 10:15 PM   #53
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HI
We did try to substitute the BDW with MJ11015 ,16 but somehow we last the warm sound and much more . The truth is the designer said MJ Darlingtons were made for industrial use not for audio purpose . He did not said not possible to use them for audio purpose . May be is possible to modify the circuit but I do not want to end up like first time !!! How I stated there are at least 11 type Darlington circuit . That is very important to .
I also tried the TIP142 and 147 were produced in Italy but I personally I didn't like them .
The guy who design these schematic he said the firs think he chose the Darlingtos from Texas Ins. BDW83/84C and built the rest of the schematic up to drive the power transistors !???
If you like mosfet output you may take a look at the Zenquito amp .
Very similar , few parts , lateral output and J-fet input .
You can even bias that in Class A mode .
Or if you want something more simple try the ProFet .Or if you think to use vertical mosfets Pass F5 is a great amp with a few components to.


Greetings
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Old 19th November 2008, 12:43 PM   #54
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Hello sakis
You right matching is not so simple when we talking about Darlington transistors .
But you can use with a great result even unmatched transistors to . I know I did listening to these amp a couple years , if I was not satisfied with the sound I would not think to build it again . I have some great sounding amp like AlephX ,Aleph2, Hiraga Class A and so on . But I want something different.
If you read at the ESP site 101 project even Rode said matching the outputs it is not so important .Of course it would improve the sound if you can do match them! You can use one pair output transistor with lower voltage to . To match PNP to NPN not many designer do or advise that .
Yes you right there are many different Darlington circuit in one case .
That is the main reason I want to stick with the original power transistors , and both PNP and NPN must be produced by the same company .That is a min. requirement here .
The rest of the transistors we can match easily .
Thanks for the warning.
For example in many electronic store they sat TIP142 &147 = BDW83C & BDW84C . That is not totally true , if you have a ECG catalog you can look them up and you can see it is not equal the two type of transistor .
Or you can even check the data of the transistors on the net .
The main reason I prefer to stick to the transistor the circuit was design for . And how you wrote the the complementary pairs must be produced by the same company at least .
Thanks for your comment . It is very useful to all of those who plan to give a try to these amp .
The schematic was downloaded more than 900 times so may be we will see some amplifiers to I hope .
We can find a lot of schematic with mosfet , bipolar, tubes but not many uses Darlington transistors .
The engineers who design the Darlington transistors into one case they had some purpose with , it is for a reason what I want to write .

Greetings
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Old 19th November 2008, 08:28 PM   #55
anatech is offline anatech  Canada
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Hi gaborbela,
Quote:
For example in many electronic store they sat TIP142 &147 = BDW83C & BDW84C . That is not totally true , if you have a ECG catalog you can look them up and you can see it is not equal the two type of transistor .
ECG /NTE are a waste of time. There are enough errors in those books to begin with. Don't bother to try using those devices.

Quote:
Or you can even check the data of the transistors on the net .
Yes!!!
This is the only way to do things. Look at the exact device and think about the true specifications.

-Chris
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Old 19th November 2008, 11:38 PM   #56
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Hello anatech
Thank for your comment , most of the time because is much faster to open the book than turn on the computer I check in a ECG Philips book.( A couple time I get spooked because I trusted in the catalog )
But if the transistor data very important like in these case I will usually double check on the net .(I did paid for my mistakes ,Usually the stores does not take back the transistors even if I didn't touch them.)
In a short sentence before I buy or order transistors I do check on the net now . How you wrote that is for sure .
ECG most of the time give just 50% info or less what we really need to know .
Sometimes a 30V transistor they put in the same category with the 100V because they has the same gain etc .
I agree with you !

Greetings
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Old 21st November 2008, 03:18 AM   #57
anatech is offline anatech  Canada
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Hi gaborbela,
Don't even look at those books. I know this is convenient, but there are better books to have.

One of the biggest dangers are those times when someone finds the ECG / NTE "equivalent", then looks for another transistor number that cross references to that same number. I have seen working technicians do this!!!

This post is for general information really gaborbela, I'm sure you know better.

-Chris
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Old 21st November 2008, 03:00 PM   #58
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I tend to agree - don't even think about ECG / NTE parts

For audio amps it's not hard to find suitable replacements for almost anything.
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Old 25th June 2009, 11:09 AM   #59
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Hello
Finally I designed the layout for the PC board and I each the boards .
Unfortunately and sadly I just realised most of those transistors are no longer in production after 20 years . They are no longer in production .
I can find BDW93C/94C which is equivalent to the bigger brother BDW83C /84C but with less power .Still it would be enough with 40V rail voltage , and I plan to use 2pair of course .
Unfortunately the driver BF469 /BF470 hard to find parts , also with BC414C /416C have the same issue .
If anybody knows any info about these transistors please inform me .
Thank you . Now after I made the PC boards I really want to build the amp .
Any help greatly appreciated .
Thank you
Greets
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Old 25th June 2009, 01:34 PM   #60
Bonsai is offline Bonsai  Taiwan
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I like this amplifiers simplicity - very elegant.

Itt would be great to hear this with the latest components.

Good luck - looking forward to the results.
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