Amplifier based on 2N3055

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#2
Hi,

This is a very old device. I used to use these for audio in the late 60's.
Although they appear to have a high Ptot, this is for a water cooled heatsink, and most samples available could never reach this even then.
There are some designs dating from the 70's that use them, including the Quad 303. (Or it used an equivalent).
One that I made at that time was this:

http://sound.westhost.com/jll_hood.htm

Not much power, but it sounded better than the Quad.

Unless you have a zero budget, I would suggest looking at some more modern devices.

Cheers,
 
#4
Re: 2N3055

nickgreek said:
Hello macgyver

John Linsley-Hood’s 15W Class-A power amp which based on 2N3055
Hi, go to
http://www.gmweb.btinternet.co.uk/jlh1996.htm
:idea:
Click to expand...

Here is a Thread about 2N3055 amplifier
with schematics.

2N3055 amplifier - thread

Have you Searched here
at diyaudio?

2N3055 is such a usual transistor, that very many amplifiers
have used this as Output devices.

/halo - now searching the web for some more - with PCB
#######################################################
Here is the results, 12 hits
for search:
Google: "power amplifier" 2N3055 PCB schematics
 
#6
A Good Old Dynaco ST120

ted said:
Another classic design based on the 2n3055 was the
Dynaco St-120. On a good day it could do 60 watts/ch
but usally about 55 watts/ch.

The sound is unique and is one of the simpliest designs of a
power amplifier.
The schematic/PCB is located at -
http://home.indy.net/~gregdunn/dynaco/components/ST120
🙂
Click to expand...
Thanks, ted

that was a Good Oldie Amp! 😉
and simple and easy to build, too
##########################################################

I recommend a visit at Ted's Website!

Ted's World of Power Amplification - Schematics & Schematics and ....

##########################################################

I like that
/halo - has got one more schematic :bulb:
 
#8
Let's not remember the NAD 3020. It also used 2N3055s. If you heat sink them really well, you can probably get 40-50 watts in an AB output amp, maybe more. But you can find devices today that are more linear with higher BETA at high currents that will likely result in a better sound that is more tolerant of the overall topology.

Alvaius
 
#11
Here is the schematic for the ST-80. Nice little amp, and about as much power as you can get out of the 3055...

From here.
 

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#12
www4.ncsu.edu/~jdchmiel/amp.zip

this is a zip of all the info that came with A Qkits amplifier kit I got once ampon a time that seems to be discontinued now. Anyways, it is rates 100x1@8ohm or 175x1@4ohm and i verified it at smoke X lots @ 2ohm. I am going to replce the fried 3055's with MJ15003's as it was reccomended to me on this board as being a better all around transistor. This schematic and parts list might help you get started tho..
 
#13
ST-120 has 2n3055 (Really)

On many versions of the ST-120 that were kit built, the output's were indeed 2n3055. Reviewing the parts list of my ST-120 Q5/Q6 were 2N3055 Dynaco Part # 571844. (Serial number 17828060).
Another test to see what version you have, look at Q3/Q4 (drivers). If they are 2n3053/2n4037 and NOT the TIP's, then you have a older kit version of the ST-120 that has not been modified.

On later models they did switch to a better output/drivers.

The reason a 2N3055 works is due to the regulated 72V power-supply. That's right the ST-120 actually had a regulated supply.
You may ask, but wait the 2N3055 has too low a Vceo. That is true but it does have a Vcer of 70 volts and a Vcb of 100V. Thus allowing a 2N3055 to just squeek in, assuming a little power supply droop.

The regulated supply is what I feel gives this amplifier it's unique sound even with slow outdated outputs such as 2N3055's.

🙂
 
#16
Well, for what it's worth, I just switched an ESP3A amp from 2N3055/MJ2955 to the MJ15003/15004. There was a significant difference. It sounded pretty good before, but sounded far better afterwards.
I have some spare old 2N3055s if you wanna drop by to pick 'em up...
 
#17
Re: ST-120 has 2n3055 (Really)

ted said:
On many versions of the ST-120 that were kit built, the output's were indeed 2n3055. Reviewing the parts list of my ST-120 Q5/Q6 were 2N3055 Dynaco Part # 571844. (Serial number 17828060).
Another test to see what version you have, look at Q3/Q4 (drivers). If they are 2n3053/2n4037 and NOT the TIP's, then you have a older kit version of the ST-120 that has not been modified.

On later models they did switch to a better output/drivers.
Click to expand...
Hmmm..I didn't know that. All the 120's I'd seen had the 3772's.

Live & learn.
 
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