hello, how about this booster for amplifier

[denver]

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]

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]

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]

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]

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]

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]

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]

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

-Chris

 

[clem_o]

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]

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

 

[denver]

hello

hi all.. tnx for you comments, i have also a diagriam of booster using a 2N3055..i love this booster because of low supply and cheep parts here in the philippines, for now i have my complete unit use to my tricycle with a 7 band equalizer and an amplifier using a AN214 ic sounds good..i like the bass punch and the treble...if your wish to send you a clearer diagram pls post your email then i send you..

cheers...

 

[denver]

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

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

hi i will post here the diagram using 2N3055, i need to scan it again, i got those diagram on solid state book sell by the electronic shop here in my country...how about replacing the transistor? like MJ1004?

 

[denver]

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

hi audio..

nice to meet your here.. were only one...by the way what can you say about it? the booster and the amplifier i have? sorry to tell you that im not good in electronics, its only my past time a hobby kumbaga, hehehhe im a computer technician but i want to learn more about electronic so i try to building repairing my own amp, and searching here on the net, and thanks god i found diyaudio.... in loaog city the tricyle amp use a booster and 7 band eq. and the amp is not an214 ic its AN7156, bridge output...

cheers..

 

[audiomachines]

hello denver,

I feel you bro i would suggest putting a 1000uF 25V electrolytic cap on one of the "hot" output terminals of the bridge IC, so you would need 2 caps. one for each channel. this would provide dc isolation since both of your outputs are floating (not reference to ground) and this will also protect your power IC from poping out due to the very low impedance of the input transformer, if you use the 2N3055 version you wiill need mica insulators for your output trannies. I have also tried your setup ha ha ha, Its nice to look back where you got started and its good that someone remember this lowly booster amp, like them or not they are part of your audio history,just as the same as those Altec horns, amps, the VOT s etc. good luck on your projects and most important have fun and take pride on your projects

regards,
audiomachines

 

[denver]

hello denver,

I feel you bro i would suggest putting a 1000uF 25V electrolytic cap on one of the "hot" output terminals of the bridge IC, so you would need 2 caps. one for each channel. this would provide dc isolation since both of your outputs are floating (not reference to ground) and this will also protect your power IC from poping out due to the very low impedance of the input transformer, if you use the 2N3055 version you wiill need mica insulators for your output trannies. I have also tried your setup ha ha ha, Its nice to look back where you got started and its good that someone remember this lowly booster amp, like them or not they are part of your audio history,just as the same as those Altec horns, amps, the VOT s etc. good luck on your projects and most important have fun and take pride on your projects

regards,
audiomachines

hi audio..

tnx alot for the info. and i tried also using the 2N3055 but my final is using the MJ because it attached directly to the ground or to the heatsink no need mica insulator, i forgot to scan the booster using 2N3055 and i have also a schematic using a parallel transistor for booster may be i post it tommorow..i like my work, it makes me happy when i power it, i dont know why somebody dont like booster, it easy to make and compatible for low amp. BTW, i have an amp with an ouput transistor of 2n3055 i need to supply it 35-0-35, so i need a transformer that have 25-0-25, but icant find here in my location (Vigan City), they sell only 12-0-12 6 ampere is this work fine for my amp?

 

[audiomachines]

hello denver,

don't be offended when our fellow diyers give their comments or perception about a certain project, they are only trying to help you, putting you in the right path. saves time and money by doing and going the right way, you see that booster to tell you the truth has a very high distortion and a battery hog. If you care about sound quality that booster wont qualify, have you ever heard a sound system where you can "see" the performers where they are placed on a stage? or
hear the singer draws a quick breath between the words of a song? or you can tell that the snare drum is treated with a reversed gate reverb by the engineer? well there is. You see the golden rule in designing an amp " straight wire with gain". Regarding your question about your amp,it will work but it may sound distorted and will not deliver the rated power on the specified load. You see amplifier output power (watts into 8 or 4 ohms) depends on the power supply, the higher the potential of your power supply the more powerful it is but of course this is per design. An amplifier designed for a +/-50 operation should not be operated higher than the recomended power supply. Your asking for trouble if you did.

regards,
audiomachine

 

[TomWaits]

Blast from the past

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.

This is exactly the unit I remember! No they did not work very well but they did function. I recall these things being hooked up to 8-Tracks and bad cassette radios. There wasn't much on the market so these things were in demand. I never did see the enhanced power versions.

...maybe you could construct a gainclone with a simple voltage divider on the input so you could feed it with speaker level signals...

I assume this is for car audio? Why not build a tiny gainclone as audiomachines advises? If I had the parts lying around for your circuit, I would make it anyway just to hear it again and laugh but if I was seriously looking for more power I would build something more practical and usable.

Awesome circuit. I never would have remembered it with seeing it here.

Cheers,

Shawn.

 

[djQUAN]

have I missed that much? I started with those amplifier kits using IC's. I never thought about using those when I was just starting....

I never would have remembered it with seeing it here.

me too!


denver,
since you're already happy with the sound of your unit, then you will be much happier when you try "real" amplifiers with real power.

 

[denver]

hello denver,

don't be offended when our fellow diyers give their comments or perception about a certain project, they are only trying to help you, putting you in the right path. saves time and money by doing and going the right way, you see that booster to tell you the truth has a very high distortion and a battery hog. If you care about sound quality that booster wont qualify, have you ever heard a sound system where you can "see" the performers where they are placed on a stage? or
hear the singer draws a quick breath between the words of a song? or you can tell that the snare drum is treated with a reversed gate reverb by the engineer? well there is. You see the golden rule in designing an amp " straight wire with gain". Regarding your question about your amp,it will work but it may sound distorted and will not deliver the rated power on the specified load. You see amplifier output power (watts into 8 or 4 ohms) depends on the power supply, the higher the potential of your power supply the more powerful it is but of course this is per design. An amplifier designed for a +/-50 operation should not be operated higher than the recomended power supply. Your asking for trouble if you did.

regards,
audiomachine

hi audio...yeah i know it, im not offended to our fellow DIY members bec. they want to help me so i accept all comments and i'm here to learn

yeah i heard some sytem use on the stage like the battle of the band concert, and its sounds good.. if you mind can u give me an schematic of amp 100w stereo and all components are avialable here in the Philippines...i have a schematic of 100w on the book titled "Practical Electronic, Solid State Servicing" but i dont know if the components are still available here....

tnx........

 

[denver]

denver,
since you're already happy with the sound of your unit, then you will be much happier when you try "real" amplifiers with real power. [/B][/QUOTE]


hi djQUAN...

yeah, but i guess i must try to build the real amp as you suggested...BTW do u have the schematic of 100w stereo amp? all components are available here in Philippines..tnx...