hello, how about this booster for amplifier

denver · 24th August 2006, 06:44 AM

hello everyone, what can you tell about this booster? for me i love it. i dont know why bec. its realy good for low power amplifier... any comment should be appreciated.. tnxx....

unmibh · 24th August 2006, 09:01 AM

Hi Denver,

I remember them , it was a hit in the 80's , I built one as well during those days and I was surprised how good it is considering using so few parts. I would like to build one again using newer transistor in place of the 2955 but I don't know if the transformer are still available.

cheers
rom

Circlotron · 24th August 2006, 09:44 AM

I wonder why PNP transistors were used in the original when equivalent size NPN's are stronger and cheaper? It does use a single supply rail so that keeps things simple. In fact, it's not really that much different (conceptually at least) from the one that was here a year or so ago by someone named Susan, IIRC. Here it is.

unmibh · 24th August 2006, 10:59 AM

Hi Cylo,

IIRC, there are diffrent variation of similar circuit floating around from diffrent shops offering booster amp then where this came from. There are also NPN 2N3055's but I don't have any diagram of them now. May be Denver, have more to offer.

Cheers
rom

audiomachines · 27th August 2006, 09:11 AM

hello everyone,

I remember this booster amplifier and it still on the market today ( here in the Philippines). I used to intall this booster with the ever popular Pioneer KP 500 car stereos with a couple Pioneer PT-6 tweeters on our king of the road, the jeepney's. There are 3 version of this booster, the 50W (the one that you posted) the 100W (with 4 outputput transistors and a bigger output transformer) the 150W ( with 6 output tranies running on a 24V dc supply) and I am wondering if they are really putting out that power. MJ2955 was used so you could mount it directly on the heatsink. I remember we used to assemble these on a C bar aluminum, then a handful of LED's, resistors, 1N4148's for a simple VU meter to go.

regards,
audiomachine

anatech · 27th August 2006, 09:48 PM

Oh my!
The mind basters are back!!

These were sold as assembly with a 6" X 9" (cheap) speaker in the early 70's. Man, they sounded really bad. They were very similar to your diagram, but I think NPN 3055's.

I can't believe the concept is still around.

-Chris

clem_o · 28th August 2006, 12:17 AM

Hey Chris,

These beasts are still popular here - usually see them in pedal-powered transports (bicycle with a sidecar). The driver maintains a 12V lead-acid battery, usually tucked right under the passenger seat in the sidecar. You have them blasting away, and for the life of me I can't figure why anyone would want to ride them, with the tweeters screeching into your ears and the bass booming all over...

And yeah, audiomachines is right - the other application area would be the public transport jeeps and buses, though loud music is banned on 'real' public vehicles...

Cheers!

Clem

anatech · 28th August 2006, 12:33 AM

Hiya Clem!,
And I though they were bad way back then. I doubt they sound any better today!

-Chris

clem_o · 28th August 2006, 12:40 AM

Chris,

The quality of the metal going into the transformers was better back then. So you have a pretty good idea of what these things sound like... No offense to denver meant - perhaps his unit is one of the better-sourced ones...

Cheers!

Clem

audiomachines · 28th August 2006, 04:10 AM

hello,

but in the first place this is where i got into audio constructing these booster amps he he he he quick, cheap and dirty

no offense to denver. maybe you could construct a gainclone with a simple voltage divider on the input so you could feed it with speaker level signals. yeah i miss those days well all that matters to you is bass and your treble and don't forget to turn on that loudness contour

i remember we use to souped up those Pioneer KP 500 modifying their tone controls, this booster amp is the reason why AN214 ic's sells and got extinct. yaikess am I that old ha ha ha ha

regards,
audiomachines

24th August 2006, 09:44 AM	#3
Circlotron diyAudio Member Join Date: Jun 2002 Location: Melbourne, Australia	I wonder why PNP transistors were used in the original when equivalent size NPN's are stronger and cheaper? It does use a single supply rail so that keeps things simple. In fact, it's not really that much different (conceptually at least) from the one that was here a year or so ago by someone named Susan, IIRC. Here it is. __________________ Best-ever T/S parameter spreadsheet. http://www.diyaudio.com/forums/multi...tml#post353269

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24th August 2006, 09:01 AM	#2
unmibh diyAudio Member Join Date: Oct 2004	Hi Denver, I remember them , it was a hit in the 80's , I built one as well during those days and I was surprised how good it is considering using so few parts. I would like to build one again using newer transistor in place of the 2955 but I don't know if the transformer are still available. cheers rom

24th August 2006, 10:59 AM	#4
unmibh diyAudio Member Join Date: Oct 2004	Hi Cylo, IIRC, there are diffrent variation of similar circuit floating around from diffrent shops offering booster amp then where this came from. There are also NPN 2N3055's but I don't have any diagram of them now. May be Denver, have more to offer. Cheers rom

27th August 2006, 09:11 AM	#5
audiomachines diyAudio Member Join Date: Dec 2005 Location: silang, cavite	hello everyone, I remember this booster amplifier and it still on the market today ( here in the Philippines). I used to intall this booster with the ever popular Pioneer KP 500 car stereos with a couple Pioneer PT-6 tweeters on our king of the road, the jeepney's. There are 3 version of this booster, the 50W (the one that you posted) the 100W (with 4 outputput transistors and a bigger output transformer) the 150W ( with 6 output tranies running on a 24V dc supply) and I am wondering if they are really putting out that power. MJ2955 was used so you could mount it directly on the heatsink. I remember we used to assemble these on a C bar aluminum, then a handful of LED's, resistors, 1N4148's for a simple VU meter to go. regards, audiomachine

27th August 2006, 09:48 PM	#6
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Oh my! The mind basters are back!! These were sold as assembly with a 6" X 9" (cheap) speaker in the early 70's. Man, they sounded really bad. They were very similar to your diagram, but I think NPN 3055's. I can't believe the concept is still around. -Chris

28th August 2006, 12:17 AM	#7
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Hey Chris, These beasts are still popular here - usually see them in pedal-powered transports (bicycle with a sidecar). The driver maintains a 12V lead-acid battery, usually tucked right under the passenger seat in the sidecar. You have them blasting away, and for the life of me I can't figure why anyone would want to ride them, with the tweeters screeching into your ears and the bass booming all over... And yeah, audiomachines is right - the other application area would be the public transport jeeps and buses, though loud music is banned on 'real' public vehicles... Cheers! Clem

28th August 2006, 12:33 AM	#8
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hiya Clem!, And I though they were bad way back then. I doubt they sound any better today! -Chris

28th August 2006, 12:40 AM	#9
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Chris, The quality of the metal going into the transformers was better back then. So you have a pretty good idea of what these things sound like... No offense to denver meant - perhaps his unit is one of the better-sourced ones... Cheers! Clem

28th August 2006, 04:10 AM	#10
audiomachines diyAudio Member Join Date: Dec 2005 Location: silang, cavite	hello, but in the first place this is where i got into audio constructing these booster amps he he he he quick, cheap and dirty no offense to denver. maybe you could construct a gainclone with a simple voltage divider on the input so you could feed it with speaker level signals. yeah i miss those days well all that matters to you is bass and your treble and don't forget to turn on that loudness contour i remember we use to souped up those Pioneer KP 500 modifying their tone controls, this booster amp is the reason why AN214 ic's sells and got extinct. yaikess am I that old ha ha ha ha regards, audiomachines

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