Anyone recognise this Design..? based on LME49810

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J

junglejuice

Member
Joined 2001
AndrewT said:
are the LME498xx design any good? Look up the other threads discussing these implementations at length.
Is this particular PCB implementation any good? Buy one and find out?
Will this particular implementation drive a 2ohm or 2r0 load? Check the output stage and driver stage currents for typical operational conditions.
Click to expand...

Well that is a very helpful and insightful response.....
 
M

multisync

Member
Joined 2008
as far as driving 2ohm loads see my thread #29. I could have gone lower but the limiting factor for me was the heatsink size. If you want to drive 2 ohm loads and possibly lower I would not recommend using a power supply above +/-50-60 volts. At 2 .5 ohms I was getting >300 watts so at 1 ohm you would get ~500-600 watts which would be pushing the limits of the 5 pairs of outputs. I don't think the output transistors are matched. The bias current varied nearly 2 to 1 over the 10 devices, which would mean that hfe would also vary a lot from device to device which means that the power dissipated by each device would also vary by about 2 to 1 which means that if you push to the limit the whole board, some or all of the power transistors may blow.

Also remember that these boards were only $50 each. read as a very great deal. you get what you pay for most of the time. In the long run I may but 50 or sets of outputs and try and find 10 sets that match closer that what is now on the board.

Connexelectronic ( see vendors forums) has some similar boards for sale at his web site but at $119US Each. you may wish to contact him to see if his boards can drive low Z loads and if the output devices are matched.
 
J

junglejuice

Member
Joined 2001
multisync said:
as far as driving 2ohm loads see my thread #29. I could have gone lower but the limiting factor for me was the heatsink size. If you want to drive 2 ohm loads and possibly lower I would not recommend using a power supply above +/-50-60 volts. At 2 .5 ohms I was getting >300 watts so at 1 ohm you would get ~500-600 watts which would be pushing the limits of the 5 pairs of outputs. I don't think the output transistors are matched. The bias current varied nearly 2 to 1 over the 10 devices, which would mean that hfe would also vary a lot from device to device which means that the power dissipated by each device would also vary by about 2 to 1 which means that if you push to the limit the whole board, some or all of the power transistors may blow.

Also remember that these boards were only $50 each. read as a very great deal. you get what you pay for most of the time. In the long run I may but 50 or sets of outputs and try and find 10 sets that match closer that what is now on the board.

Connexelectronic ( see vendors forums) has some similar boards for sale at his web site but at $119US Each. you may wish to contact him to see if his boards can drive low Z loads and if the output devices are matched.
Click to expand...

So for a 2 ohm load would a supply voltage of around 40v be more appropriate?
 
a.wayne

a.wayne

Member
Joined 2008
multisync said:
as far as driving 2ohm loads see my thread #29. I could have gone lower but the limiting factor for me was the heatsink size. If you want to drive 2 ohm loads and possibly lower I would not recommend using a power supply above +/-50-60 volts. At 2 .5 ohms I was getting >300 watts so at 1 ohm you would get ~500-600 watts which would be pushing the limits of the 5 pairs of outputs. I don't think the output transistors are matched. The bias current varied nearly 2 to 1 over the 10 devices, which would mean that hfe would also vary a lot from device to device which means that the power dissipated by each device would also vary by about 2 to 1 which means that if you push to the limit the whole board, some or all of the power transistors may blow.

Also remember that these boards were only $50 each. read as a very great deal. you get what you pay for most of the time. In the long run I may but 50 or sets of outputs and try and find 10 sets that match closer that what is now on the board.

Connexelectronic ( see vendors forums) has some similar boards for sale at his web site but at $119US Each. you may wish to contact him to see if his boards can drive low Z loads and if the output devices are matched.
Click to expand...

Hello ,
Is this the same amplifier and would it require the same mods ?

http://connexelectronic.com/product...ducts_id/78?osCsid=ojg85i559162ik41d5rfaucau3
 
A

AndrewT

R.I.P.
Joined 2004
junglejuice said:
So maybe 45v would be a better option for 2 ohm use then???
Click to expand...

AndrewT said:
.......Will this particular implementation drive a 2ohm or 2r0 load? Check the output stage and driver stage currents for typical operational conditions.
Click to expand...
I really was offering advice on how to check your brief against the specification.
You chose to see it as unhelpful.
 
M

multisync

Member
Joined 2008
junglejuice,

I don't know what your application is, home hifi, Home theatre, PA for a band, disco, club, car etc, so it is impossible for me or anyone else to say, yes this board will drive any load at X watts at 2 ohms with super hifi sound that will satisfy the most critical golden ear listener.

how you implement this board will effect it's final outcome. There are many discusions on this forum as to power supply sound, rectifier sound, capacitor sound, connector sound, house wiring sound, the sound of wires, solder, power cords, rooms, speakers and on and on.

I have several pieces of stereo gear at home that many diyaudio members would reject but it serves the purpose for that application.

My basement stereo uses diy 1970's amplifiers, my critical "hifi" uses a 1980's kenwood amplifier that I like and to me sounds good. (ebay $65, 2 years ago)
Don't tell anyone but I use ordinary 16gage speaker cable.

Everything boils down to a matter of compromises and choices.

many people will say that for "average" applications using "average" speakers 100watts per channel is enough.

I believe the LME49811 was originally designed for a specific application for a client for a 3KW amplifier.

how the chip is used, how it is finally implimented in a final design, how it will perform is up to the end user. In this case you and me.

good luck and I hope this inexpensive board meets your needs and that there is still some left for sale.
 
J

junglejuice

Member
Joined 2001
multisync said:
junglejuice,

I don't know what your application is, home hifi, Home theatre, PA for a band, disco, club, car etc, so it is impossible for me or anyone else to say, yes this board will drive any load at X watts at 2 ohms with super hifi sound that will satisfy the most critical golden ear listener.

how you implement this board will effect it's final outcome. There are many discusions on this forum as to power supply sound, rectifier sound, capacitor sound, connector sound, house wiring sound, the sound of wires, solder, power cords, rooms, speakers and on and on.

I have several pieces of stereo gear at home that many diyaudio members would reject but it serves the purpose for that application.

My basement stereo uses diy 1970's amplifiers, my critical "hifi" uses a 1980's kenwood amplifier that I like and to me sounds good. (ebay $65, 2 years ago)
Don't tell anyone but I use ordinary 16gage speaker cable.

Everything boils down to a matter of compromises and choices.

many people will say that for "average" applications using "average" speakers 100watts per channel is enough.

I believe the LME49811 was originally designed for a specific application for a client for a 3KW amplifier.

how the chip is used, how it is finally implimented in a final design, how it will perform is up to the end user. In this case you and me.

good luck and I hope this inexpensive board meets your needs and that there is still some left for sale.
Click to expand...

My usage would be car auido hence the 2 ohm load part so it will be running off a swps, does that help at all????
 
S

Strung

Member
Joined 2010
300W LME49810 Mono channel Audio Amplifier Board PSU

So these are cheap and I have time and the ability to construct but not the ability to design sooooo.... here I am picking up crumbs and trying to sponge some power supply ideas.... schematics... large cheerful pictures in bright kindergarten primary colours if I should go out on a limb and buy two of these to put in a box from that nice man in HK :D who assures me that I will be happy if I give him my money.:spin:

Luv your bench Multisync, looks like mine with fewer plumbing and auto parts.
I only recognize clean up time when my legs cramp from nowhere to sit.
 
S

Strung

Member
Joined 2010
Perhaps if I shared?

I realize that it is essentially poor taste to respond to one's own post but reviving interest in a dead thread might take a bit of work.
What I want to do is replace one of these http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItemVersion&item=270590743932&view=all&tid=0 in my garage work space. It cost me a whopping $15 on ebay and seems to have sprung from a budding Indonesian electronics industry. I was intrigued by the specs and needed a giggle. It makes noise but not enough weighing in at a hefty 5 Kg.

I want my new toy to power two 15" 300w club bins via a behringer djx400 2 channel mixer http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItemVersion&item=130404720951&view=all&tid=0 which I bought for $17 and repaired.

So what we have is cloth ear'd cheap skate DIY ebay junkie with a need to fill a big workspace with large noises of not necessarily high quality who knows very little about the power requirements of amplifiers. Specifically +-45 +-60.
Humble enough?
 
S

Strung

Member
Joined 2010
Crickets

Has been built and tested but the acoustics in here are terrible.

Shares build withself?
Shares build withself?
Shares build withself?
Shares build withself?
Shares build withself?
Shares build withself?


Why bother?
Why bother?
Why bother?
Why bother?
Why bother?
Why bother?
 
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