Audio amplifier with 2n3005

[Gost22]

Hi guys!
View schemeatics this amplifier for which the author gives this
Specifications:
Power output is 60 watts into 8 Ω and 100 watts into 4 Ω loudspeaker.
Total harmonic distortion is less than 0.01 %.
Frequency range is within 20 Hz and 20 kHz.
The input sensitivity is in the vicinity of 750 mV.
The frequency characteristics lie in between 1 dB from 15 Hz to around 100 kHz.
If all this is okay?! What changes in the schematic needs to be done for this audio amlifier with power supply Ucc=+/-38V and with the output transistors MJ15003/MJ15004?
Thank you for your cooperation!

 

[Osvaldo de Banfield]

Supposing the transistors can support the voltages and currents, I don't see any important mod, perhaps R4 and R5 to maintain current in leds. The other parts are feed in constant current, so no mod necessary. Check also capacitor voltages rating (50V, mainly C6, C7 and C5).

But the schematic looks some strange. Did you forget R and a C in series from left side of R9 to ground? As is, the amplifier is unity gain.

 

[jaycee]

If you can use NPN/PNP power output transistors then you dont really need a quasi-complimentary circuit like this one. A basic Blameless type circuit will work fine.

 

[Gost22]

If you can use NPN/PNP power output transistors then you dont really need a quasi-complimentary circuit like this one. A basic Blameless type circuit will work fine.

What are the transistors in the schematic?
thank you!

 

[jaycee]

They aren't specified but the following should work:

TR1,2,3 = BC556
TR4 = MJE340
TR5 = MJE350
TR6 = MJE15032
TR7 = MJ15003
TR8 = MJE15033
TR9 = MJ15004
TR10,11,12 = BC546
TR13 = BD139 (mount on main heatsink)

 

[Samuel Jayaraj]

The schematic in post#1 is very similar to a circuit published in Elektor just after the release of the Crescendo and Mini Crescendo designs, except that instead of LEDs, the CCS were referenced with zener diodes. I had built several of those amps and thought they sounded very good for their time, especially with a fully regulated PSU.

 

[Gost22]

The schematic in post#1 is very similar to a circuit published in Elektor just after the release of the Crescendo and Mini Crescendo designs, except that instead of LEDs, the CCS were referenced with zener diodes. I had built several of those amps and thought they sounded very good for their time, especially with a fully regulated PSU.

Hi Samuel!
If you are unable to view the schematics.
thank you!

 

[Gost22]

PCB for this audio amplifier

Hello!
Mr. Yaycee please show your PCB for this audio amp if you have one.
Thank you!

 

[alayn91]

Hello,

Unfortunately, in post n°1, I'm afraid T10 is useless, with its Vbe = 0V.

 

[Gost22]

Hello,

Unfortunately, in post n°1, I'm afraid T10 is useless, with its Vbe = 0V.

That's it! is missing something, but what?😕🙄

 

[stevenrotterdam]

Like T14...

 

[Gost22]

Hi guys'!
T10 and T14 badly off line, how to connect them?🙄😕
thank you!

 

[jaycee]

Hello!
Mr. Yaycee please show your PCB for this audio amp if you have one.
Thank you!

I don't but there are plenty of amps based around this sort of schematic. For example you may build the Destroyer X amplifiers (search this forum) using the MJ15003/4 output transistors if you wish.

 

[east electronics]

Except others pointed there is issues in the output stage ,,,, this is short of copy of P68 from ESP pages which is class AB +B design and will have some issues when it comes to bandwidth ...it also seems that someone made patchwork between some circuits and expect forum people to debug the circuit ...

 

[Gost22]

Hi jaycee!
Mr Jaycee much I like your schematic up the so I ask for your PCB schematics!😉 (see schematic-new)
The audio amplifier to put up your schematic and give an opinion as it sounds.
Thanks and Cheers!
P.S.
I apologize for my poor English!?

 

[Samuel Jayaraj]

Hi Samuel!
If you are unable to view the schematics.
thank you!

Did I say something irrelevant?

 

[Ian Finch]

The design posted by jaycee is in fact a model design described as "blameless", designed by Douglas Self for his books like "Audio Power Amplifier Design Handbook" in all 6 editions.
If you want to get details, even see pics of modules based on this design, it would be smart to get a copy of the book, even second hand, read free excerpts or search the design on the net for yourself.

It is an extremely low distortion design when built with his specified components and boards but 2N3055s ? heh heh...nope! There are no PCB patterns in Self's books so if want someone to draw PCBs for you, you might have to look at other designs on the forum or the web.

 

[selim]

Hi Gost22,

The circuit you published in your post #1 is very similar to the one
published in Elektor 1982 Summer Circuits, as Samuel has pointed out in
his post #6.But your circuit is lacking quite few resistors and will not work
as shown.

I also share the opinion with Samuel that the Elektor amp was quite good for
its time, and I believe that it is still quite good even by today's standarts.
I have modded that amp to work with NPN + PNP pairs and I have quite few
PCB's leftover.If you are, or anybody else, interested in having a go, I can
gladly supply the PCB's, just drop a mail to me ( selim_ardali at yahoo dot com ).

Cheers

Selim

 

[Gost22]

Hi Selim!
Give the show a schematic of Elektor in 1982 years, also give display PCB.
thank you!
Cheers!

 

[donpetru]

Let me show you another diagram audio amplifier that works very well. Can be adapted to work with complementary output transistors.