Topic: "LEACH Amp"1000 watts double barrelled topology for SUBwoofer

[JojoD818]

yup, i finished stuffing the 6 trannie boards, have all the parts, but still lacking the chassis to house it.... i have six conrad heatsinks, and 12 3inch electros, 47kufd/100v and 68kufd/100v....i have acumulated lots of parts from apexjr. and from the variuos group buys in diyaudio....

i now have a collection of about 800 tubes....most of them are 1 dollar ones....still adding more....i plan to buy from the ussr sometime...

i have also acquired 2 oscilloscopes from singapore...i am getting ready for that eventual day when i will have more time for projects...

deym! that's one hell of a retirement package!!!

kung pwede nga lang magpabili sayo, hindi electronics ipapabili ko kungdi isang authentic, Russian made Kalashnikov... whew! 

[Lilo_improbum]

sir tony, ang dami nyu nang amp... hehe collector cguru kayu? hehe      ako lng naman is dat I want a "Leach Amp " that can drive a 2  1000 watts 18 inch subwoofer.... a  "Leach amp "dat is 4 ohms stable and good for 24/7  operation... hehe in short a proffesional type sound system na ang gustu ko... di na pang home theater pang bakuran na... hehe      pero dahan dahan ko lng naman gagawin yun..I have to save for that costly hobby... hehe

[ATJr.]

@jojod,

wish it was that easy, sa airport pa lang kalaboso na.....

@lilo,

if you want a professional amp, then the leach amp may not be for you, for one the leach amp has a gain of about 19, professional amps have gains in the ~40 range, they are driven from a mixing console most of the time......besides as i said earlier, the leach amp is too nice sounding to be used for mere subwoofer duties, sayang....

perhaps what you really want is a classD amp....lots of projects on class D, you can ask jojod about it.

look at the rod elliot site, there are some very nice projects there

[JojoD818]

Hi Tony,

Yup, I'm sure you'd also like to have one of those beauties but then again hanggang pangarap lang tayo... 

[Lilo_improbum]

Sir tony not sayang.. hehe   Well, i have 2 amp3 from pilyo driving a 4 15 inch dai chi subs... well i want to put my attention to clear mid and highs on  this time...Is Leach amp will be a nice catch to have, driving a tweeter and midrange speaker?? di ba sabi nyu its not tiring to the ears. . .
 sir tony , sisingit ko lng ha sa Bacolod pala may nakagawa dun amp use to drive Subs Modified Westrack having 32 by 32 power driver transistors sa output..32 2SA1216 and C2922. . ...Ginagamit nila yun pang mobile, ok din kaya yung gawa nila? operational naman, speakers are connected series parallel... . 
 
@adrianm

 parekoy ask lng ako pwd mu ba ako bigyan nang idea kung magkanu ang nagastos mu sa Leach amp.. Estimation lng , all in    expenses mu nung ginagawa ang project hanggang  operational na.. thanks!

[ATJr.]

Is Leach amp will be a nice catch to have, driving a tweeter and midrange speaker??

yes.....

sisingit ko lng ha sa Bacolod pala may nakagawa dun amp use to drive Subs Modified Westrack having 32 by 32 power driver transistors sa output..32 2SA1216 and C2922. . ...Ginagamit nila yun pang mobile, ok din kaya yung gawa nila? operational naman, speakers are connected series parallel... .

output power is not determined by the number of transistors used, but rather by the ouput voltage developed accross those speakers, and the impedance that those speakers presnt to the amplifier...

now the number of power transistors determines how robust the amp is, the SOA af any amp increases as the number of output devices increases.....you can't go wrong with many output devices....

[adrianm]

one channel cost me 1.1k (psu, heatsink and tranparencies not included). MJ15003 and MJ15004 is arround Php161.00 each.

i wasted a lot of money on the transparencies, it took me 4 prints before i came out with an acceptable layout (no errors). lesson: don't print your layout to transparencies unless you had a complete thorough check on the layout and sure that everything is in order.

[Lilo_improbum]

ilang MJ's ang nagamit mu??? meron kasi ako d2 Sam Elex Power amp Schematic diagram with PCB Lay out.. 300 watts RMS using 2 MJ15003 and 2  MJ15004... anung design ang nagawa mu parekoy ?

[adrianm]

2-mj15003 and 2 mj15004. the leach amp i built was the one called low tim amp (120 watts @ 8 ohms load).

[ATJr.]

one channel cost me 1.1k (psu, heatsink and tranparencies not included). MJ15003 and MJ15004 is arround Php161.00 each.

i wasted a lot of money on the transparencies, it took me 4 prints before i came out with an acceptable layout (no errors). lesson: don't print your layout to transparencies unless you had a complete thorough check on the layout and sure that everything is in order.

i had transparecies made by a local printing shop, but i never got around to using it, instead i had silkcreens made and used paint instead...

the original ON-SEMI to-3's can be had as free samples but you will have to pay for freight, anyway you can check the ON-SEMI website, they even have local sales reps here so you can get original parts from them.

[ATJr.]

2-mj15003 and 2 mj15004. the leach amp i built was the one called low tim amp (120 watts @ 8 ohms load).

when using platic power trannies, one metal to-3 is to correspond to 2 plastic parts, so what this means is for every 2 metal parts, there should be 4 plastic power trannies....

reason being, SOA, (safe operating area) is about half for the plastic parts compared to metal parts......

[Lilo_improbum]

same lng pala sa ginawa ni sam .. 2 by 2 mj's pnp and npn...  maybe in configuration magkaiba sila..I had ask dun sa amin nang  nasa Bacolod pa ako selling mj's power transistor for 270 pesos...WheW! mahal pero ok lng basta original MJ 15004 and 15003... Adrianm... hehehe hope you can help me building my Leach amp ...in Pcb, installation instruction  and biasing... sana hehe "LEACH AMP " Brader.. 

   I nid a PCB like what you did..Pag may subra kang nagawa dyan pwd ko bang bilhin yan?? hehehe  well thanks for the info brad!        

[adrianm]

sir lilo,

i only made 1 pcb, no extra. this is my 1st build of leach amp and this is just a prototype.

[aHobbit]

...i am getting ready for that eventual day when i will have more time for projects...

Your future (eventual day) looks dim to me

Personally, I have to condition myself to accept the fact of my life 

- when we are young then, we have all the time and energy - BUT NOT THE MONEY!   
- now that we are working, we have all the money and energy - BUT NOT THE TIME!    
- that eventual day  , that we retire  , we have all the time and money - BUT NOT THE ENERGY!!!  

    

At least, don't stop dreaming ... the motivation to do what can be done now ... hats off to you!!! 

[ATJr.]

Your future (eventual day) looks dim to me

Personally, I have to condition myself to accept the fact of my life 

- when we are young then, we have all the time and energy - BUT NOT THE MONEY!   
- now that we are working, we have all the money and energy - BUT NOT THE TIME!    
- that eventual day  , that we retire  , we have all the time and money - BUT NOT THE ENERGY!!!  

    

At least, don't stop dreaming ... the motivation to do what can be done now ... hats off to you!!! 

@aHobbit,

how true, now i have the money to spend but not enough time to do diy stuff..... :'( i give myself two more years and i will more or less be free from parental obligations, my kids will graduate in college......

this is also one reason to post in forums, maybe i can help others, specially newbies get on their way, that gives me even greater pleasure.......

[Lilo_improbum]

ok..   :'(  one day restday lang kasi ako, then I work for 12 hours everyday sa Solar Company.. too busy...hehehe Hmm?? sige pagtyagaan ko na lng every Restday....Draw, Etch,  drill and assemble... maybe in 3 months time matatapus ko din... Salamat brader.. ok lang yun, importanti dami natin sa Leach Amp.. hehehe   

[alexdnatel]

I built a Leach amp (stereo)  back in 2001. I think it cost me 9k all in all and sold to my boss around 12k. Now I still have the mono working & the other boards missing transistors. I remember back then there were resistor values that are not available at raon, I have order at RS component Phils.Output transistors were very expensive and really have to look for the genuine MJ15003/4 or else with high volume comes a smoke out of your amp. excellent amp.

[ATJr.]

I built a Leach amp (stereo)  back in 2001. I think it cost me 9k all in all and sold to my boss around 12k. Now I still have the mono working & the other boards missing transistors. I remember back then there were resistor values that are not available at raon, I have order at RS component Phils.Output transistors were very expensive and really have to look for the genuine MJ15003/4 or else with high volume comes a smoke out of your amp. excellent amp.

indeed....

lot's of better than MJ15003/15004 trannies have been developed since such that there is no more need to stack up the trannies like leach did in the 70's.....