Hello, i'm seeking for a way to apply a few of these chips i have in the scrap box, and was wondering of a nice amplifier, maybe around 100W. I will gladly sacrifice power to have better quality, but with these parts, i know there are limitations 🙂
Seen a few around the internet, but failed to get the complete project, that is:
Schematic, pcb, parts list, layout and some sort of alignment indications if necessary.
Would be appreciate some pointers to a nice proven project.
Best regards,
JC
Seen a few around the internet, but failed to get the complete project, that is:
Schematic, pcb, parts list, layout and some sort of alignment indications if necessary.
Would be appreciate some pointers to a nice proven project.
Best regards,
JC
More than one pair will be needed to get 100W, and the 60V maximum voltage will make it tough to even get 100W into 4Ω.
Perhaps you might build a bridge amp for 8Ω?
Perhaps you might build a bridge amp for 8Ω?
thank you for your input djk 🙂
I found this:
http://www.diyaudio.com/forums/solid-state/242341-audio-amplifier-2n3005-3.html
later on i found this:
400W project
pcb
I really don't want to go any way above 100W because that's a lot of noise for my ears...
I found this:
http://www.diyaudio.com/forums/solid-state/242341-audio-amplifier-2n3005-3.html
later on i found this:
400W project
pcb
I really don't want to go any way above 100W because that's a lot of noise for my ears...
100W/2N3055 seems to be an evergreen formula for amplifiers that has been around more than 40 years. A single pair of 2N3055s will produce 40W into 8R and more into 4R but that's actually plenty of noise - more than enough in most homes.
This is a favourite design that dates back to around 1980 - I know of 4 stereo builds still working too!
This is a favourite design that dates back to around 1980 - I know of 4 stereo builds still working too!
Attachments
Hello Ian,
You just provided the schematics of my all time favorite Elektor design. I built it almost entirely with components from my scrapbox. The whole thing did ot cost me more than a handful of (now) Euro's. The design came without a PCB, but that was quite simple making a layout that roughly followed the schematic.
One of the very few amps I built that performed flawlessly right from the start.
A very very nice design that rivalled my Crimson 608 a somewhat comparable design with the famous Quad Triples as an output stage.
Around 1981 a design with complementary triple output stages (305/2955) was published in WW by a certain gentlemen named B. Cody, if memory serves me well..
Both the Elektor and WW designs are highly recommended for building.
BTW😀o not let the "a 100 mHz output device is necessary for hifi" guys scare you off.
Good Luck,
Eelco
You just provided the schematics of my all time favorite Elektor design. I built it almost entirely with components from my scrapbox. The whole thing did ot cost me more than a handful of (now) Euro's. The design came without a PCB, but that was quite simple making a layout that roughly followed the schematic.
One of the very few amps I built that performed flawlessly right from the start.
A very very nice design that rivalled my Crimson 608 a somewhat comparable design with the famous Quad Triples as an output stage.
Around 1981 a design with complementary triple output stages (305/2955) was published in WW by a certain gentlemen named B. Cody, if memory serves me well..
Both the Elektor and WW designs are highly recommended for building.
BTW😀o not let the "a 100 mHz output device is necessary for hifi" guys scare you off.
Good Luck,
Eelco
A single pair of 100W BJT output devices will get you a reliable 40W amplifier that can tolerate severe reactance speakers.
2pr gets you upto 80W and 3pair gets upto 120W
These higher power versions will be limited by the maximum supply rail voltage.
A 100Vce0 device should not be used on supply rails exceeding ±49Vdc
If you want to use a 35-0-35Vac transformer then I recommend you use >120Vce0 transistors. But do check the temperature de-rated SOA at the supply rail voltage. Some are terrible when operated at half max Vce0.
Good to know someone else likes it too, for a design that seemed unpromising so long ago. It's actually the Crescendo design adapted to use craptanium BJT output transistors. I think though, it has much better performance and SQ than typical EF2 2N3055/MJ2955 complementary designs, which is why I suggest it in preference.
There's a larger image of the article here: http://www.diyaudio.com/forums/solid-state/242341-audio-amplifier-2n3005-3.html
PDF (french text) here: https://docs.google.com/file/d/0BwTS40IaQa16NXJON2tZSHc1b2s/edit
"A 100Vce0 device should not be used on supply rails exceeding ±49Vdc"
Except the 2N3055 is only rated at 60V
http://www.onsemi.com/pub_link/Collateral/2N3055-D.PDF
I did a commercial design in 1997 using the 3055/2955 pair on ±30VDC, it sounded fabulous. I bought the outputs from Allied for about $0.59 each, and used $0.08 driver transistors (MPSA06/A56), with the NE5532 for the front end.
*******************
" Yes, in 1997 DJK designed several products for the Minnesota company I was working for then.
He designed a 40 watt amplifier with a really novel circuit design that was the size of a 3.5" computer hard disc drive.
The sound quality was simply amazing ! ! ! ! !
Resolution, sound stage size, timber and dynamic punch were very noticeably superior to reference amplifiers (with Musical Concepts mods) ADCOM 555, B&K ST-202 and Parasound HCA-1500A designed by John Curl.
No, 40 watts does not play as loud as 100 or 200 watt amps.....however the dynamic contrast and resolution was superior !
To this day it is still one of the finest sound quality amplifiers that I have ever heard.
Sadly, the Minnesota company closed before DJK's design made it into mass production."
Except the 2N3055 is only rated at 60V
http://www.onsemi.com/pub_link/Collateral/2N3055-D.PDF
I did a commercial design in 1997 using the 3055/2955 pair on ±30VDC, it sounded fabulous. I bought the outputs from Allied for about $0.59 each, and used $0.08 driver transistors (MPSA06/A56), with the NE5532 for the front end.
*******************
" Yes, in 1997 DJK designed several products for the Minnesota company I was working for then.
He designed a 40 watt amplifier with a really novel circuit design that was the size of a 3.5" computer hard disc drive.
The sound quality was simply amazing ! ! ! ! !
Resolution, sound stage size, timber and dynamic punch were very noticeably superior to reference amplifiers (with Musical Concepts mods) ADCOM 555, B&K ST-202 and Parasound HCA-1500A designed by John Curl.
No, 40 watts does not play as loud as 100 or 200 watt amps.....however the dynamic contrast and resolution was superior !
To this day it is still one of the finest sound quality amplifiers that I have ever heard.
Sadly, the Minnesota company closed before DJK's design made it into mass production."
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Hi anvilpt,
If you are interested in the Elektor amplifier mentioned in your first find, I still
have quite few PCB's available.just mail me at selim_ardali at yahoo dot com
with your address and I'll send you some. This offer is open to any fellow DIY'er
in this forum.This amp is a very fine example of getting stellar sound from old
3055 / 2955 pairs. There are quite few friends in this forum building this amp
with great satisfaction. I think it is well worth a try.
Best Regards
Selim
If you are interested in the Elektor amplifier mentioned in your first find, I still
have quite few PCB's available.just mail me at selim_ardali at yahoo dot com
with your address and I'll send you some. This offer is open to any fellow DIY'er
in this forum.This amp is a very fine example of getting stellar sound from old
3055 / 2955 pairs. There are quite few friends in this forum building this amp
with great satisfaction. I think it is well worth a try.
Best Regards
Selim
The Elektor amplifier looks good, and I would add some emitter degeneration resistors to the diff pairs.
(an easy mod similar to the Leach amplifier design)
(an easy mod similar to the Leach amplifier design)
Here is circuit of 1980's Maplin 225WRMS in to 4 ohms power amplifier.
You might struggle finding some transistors but I found them on ebay.
I used one in a mobile disco for a few years. It was very loud and never let me down.
I think the supplies were +/- 45VDC.
I bought one a while back minus output transistors.
I put in new ones but it oscillated.
I found I needed 10R in series with output transistor bases to slow them down a bit.
You might struggle finding some transistors but I found them on ebay.
I used one in a mobile disco for a few years. It was very loud and never let me down.
I think the supplies were +/- 45VDC.
I bought one a while back minus output transistors.
I put in new ones but it oscillated.
I found I needed 10R in series with output transistor bases to slow them down a bit.
An externally hosted image should be here but it was not working when we last tested it.
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That has to be bridged amplifiers, using selected transistors with those high rail supplies as you'd need to get an honest 225 W/8R. See this 1975 ETI UK article based on the Oz ETI 413 design from Feb. 1973 - very similar, I think.
http://www.epanorama.net/sff/Audio/Circuits/Power_amplifiers-linear/200W Bridge Amplifier.pdf
Probably not.
I did several things no one approves of, and 'everyone knows' it can't possibly sound good (it is a class 'B' CFP design with 3x voltage gain).
I have done a new mono board with a better opamp and better outputs, it is the size of a credit card. I may release that one when it is ready.
I did several things no one approves of, and 'everyone knows' it can't possibly sound good (it is a class 'B' CFP design with 3x voltage gain).
I have done a new mono board with a better opamp and better outputs, it is the size of a credit card. I may release that one when it is ready.
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