Hi Rsavas. You run two ground wires from the pcb back to psu ground. I think you create an earthloop when the 0R is in place.
I can experiment with different grounding arrangements (such as what you have done and AndrewT suggest) to see if they improve the measurements such as THD and IMD
Has anyone else done THD/IMD measurements on their setups?
Has anyone else done THD/IMD measurements on their setups?
heat and cooling of LME49830-amp
Hi guys,
I think about putting 4 pieces of the LME49830-amp into one 5U enclosure, but I'm not sure if the cooling might be enough for four amps with a bias of 360mA. Do you guys have any experience with the generated heat?
By the way: I'm also really interested in THD/IMD measurements with different grounding arrangements. So if anyone played around it, please let us know!
Thanks,
Stammheim
Hi guys,
I think about putting 4 pieces of the LME49830-amp into one 5U enclosure, but I'm not sure if the cooling might be enough for four amps with a bias of 360mA. Do you guys have any experience with the generated heat?
By the way: I'm also really interested in THD/IMD measurements with different grounding arrangements. So if anyone played around it, please let us know!
Thanks,
Stammheim
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Could you buy a couple of big external heatsinks and fit them to the case sides and screw the ALFETs direct to those? As post 2477.
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360mA and the rail to rail voltage allows you to predict the heat that needs to be dissipated.
Add up for all four and model the heatsink
Hi guys,
I recognized following:
The empty PCB has no connection between LME-IC and the transistors, but there is a connection when the PCB is populated. Ist that OK?
As I want to power the LME and the transistors seperately I have several ground-designs I am thinking of...
Many thanks,
Stammheim
I recognized following:
The empty PCB has no connection between LME-IC and the transistors, but there is a connection when the PCB is populated. Ist that OK?
As I want to power the LME and the transistors seperately I have several ground-designs I am thinking of...
Many thanks,
Stammheim
3U and 4 channels can work perfectly:
http://www.diyaudio.com/forums/soli...84.html?highlight=sa2012+lme49830#post4643484
and
http://www.diyaudio.com/forums/soli...65.html?highlight=sa2012+lme49830#post3753565
4 x 190W@8R, about 250 - 300 mA bias total per channel. 3 Pair IRFP240/9240 per channel.
2 of 4 channel can deliver the 190W continuous without heat problems.
Maybe you need 5U cooling if you plan to deliver all 4 channels full power continuous.
BR, Toni
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Sir please sorry me because i am coming with very stupid question.
I am building lme49830 based amplifier with output device 2sk1058 and 2sj162.
In datasheet of both devices it is clear that both have pinout from left to right are gate souce and drain. Mosfet k1058 drain connected to +vcc and souce connected to dmm pin to measure quiescent current another mosfet sj162 source connected to dmm another pin and third last mosfet pin connected to -vee.
Now problem is when both gate disconnected sj162 heated abruptly with smoke. My design based on amp48 schematic and suppy voltage is too low for testing purpose 25-0-25 thnx in advance for suggesting me if i have done something wrong with devices
I am building lme49830 based amplifier with output device 2sk1058 and 2sj162.
In datasheet of both devices it is clear that both have pinout from left to right are gate souce and drain. Mosfet k1058 drain connected to +vcc and souce connected to dmm pin to measure quiescent current another mosfet sj162 source connected to dmm another pin and third last mosfet pin connected to -vee.
Now problem is when both gate disconnected sj162 heated abruptly with smoke. My design based on amp48 schematic and suppy voltage is too low for testing purpose 25-0-25 thnx in advance for suggesting me if i have done something wrong with devices
Are you testing the devices stand alone?
Or are they in circuit when you are measuring?
I am testing mosfet alone. But in circuit same situation occur. I want to ask are my mosfet connected correctly k1058 3rd terminal drain connected to +vcc and j162 3rd terminal drain connected to - vee and remain to middle terminal (source) connected together.
Thnx
Thnx
Hi guys,
I got a problem with my LME49830 boards and hope that anybody can help...
I measure a sine-signal of rock-solid 10MHz/1,2Vpp in the output when I connect the signal-cable to the board, no change if a source is connected or not.
Tried three boards, no matter where the boards are built within the enclosure. I also tried a passive filter directly at the board's input, no change.
Does anybody have an idea?
Regards
Stammheim
I got a problem with my LME49830 boards and hope that anybody can help...
I measure a sine-signal of rock-solid 10MHz/1,2Vpp in the output when I connect the signal-cable to the board, no change if a source is connected or not.
Tried three boards, no matter where the boards are built within the enclosure. I also tried a passive filter directly at the board's input, no change.
Does anybody have an idea?
Regards
Stammheim
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Do you have an output zobel R/C?
Are the correct components installed? Since the problem is all pcb's then it sounds like it is a common problem
What did you use for the feedback capacitor. It is spec'd to be a silver mica!
What MOSFETs are you using?
What is you power supply arrangement?
Lots of stuff to sort out
Are the correct components installed? Since the problem is all pcb's then it sounds like it is a common problem
What did you use for the feedback capacitor. It is spec'd to be a silver mica!
What MOSFETs are you using?
What is you power supply arrangement?
Lots of stuff to sort out
Hi...
Sorry for late response! My signal cables seemed to be of poor quality, I used another and had a good result then.
Unfortunately it wasn't the last problem... Connecting my RME UCX to the amps I get a hum, which is similar to the 50Hz noise. The signal cables are around 25 centimeters and the amps are dead silent when nothing is connected.
The amps and the UCX are using a common ground, as I use a linear power supply for it (same noise with original SMPS).
My assumption is that disturbances through the signal-cable's shield winding influence the LME49830's GND and also the signal-in, which is connected to GND within an unbalanced scenario.
My question is:
Is that possible and should amps generously be used balanced, when the source has also balanced outputs?
Can GND get so much disturbed to influence the input (and of course the output signal)?
Many thanks
Stammheim
Sorry for late response! My signal cables seemed to be of poor quality, I used another and had a good result then.
Unfortunately it wasn't the last problem... Connecting my RME UCX to the amps I get a hum, which is similar to the 50Hz noise. The signal cables are around 25 centimeters and the amps are dead silent when nothing is connected.
The amps and the UCX are using a common ground, as I use a linear power supply for it (same noise with original SMPS).
My assumption is that disturbances through the signal-cable's shield winding influence the LME49830's GND and also the signal-in, which is connected to GND within an unbalanced scenario.
My question is:
Is that possible and should amps generously be used balanced, when the source has also balanced outputs?
Can GND get so much disturbed to influence the input (and of course the output signal)?
Many thanks
Stammheim
Warning: LME49830TB IC is obsolete from vendor TI/National
I got pretty excited about this LME49830TB, wonderful part. Just one problem, TI discontinued it. Maybe someone will clone it in Asia?? In the meantime, you can still get them on the surplus market, but be aware it is no longer in production and future supplies are uncertain. If you have a product in production, you may want to make a lifetime buy of available parts.
http://www.mouser.com/Search/Refine.aspx?Keyword=lme49830
Incidentally, the LM4702 is also obsolete from National/TI.
http://www.mouser.com/Search/Refine.aspx?Keyword=lm4702
It seems TI made a decision to go Class D for almost all audio amps. Digital is the future? Love that 1% distortion. For now the venerable LM3886 is still around. And I know STM makes amp chips too, so there are some low power options. But it seems that the golden days when National designers made miraculous analog ICs are waning, driven by a sensible marketing decision. Follow the money. Yah, right business answer but it sucks for audiophiles.
I got pretty excited about this LME49830TB, wonderful part. Just one problem, TI discontinued it. Maybe someone will clone it in Asia?? In the meantime, you can still get them on the surplus market, but be aware it is no longer in production and future supplies are uncertain. If you have a product in production, you may want to make a lifetime buy of available parts.
http://www.mouser.com/Search/Refine.aspx?Keyword=lme49830
Incidentally, the LM4702 is also obsolete from National/TI.
http://www.mouser.com/Search/Refine.aspx?Keyword=lm4702
It seems TI made a decision to go Class D for almost all audio amps. Digital is the future? Love that 1% distortion. For now the venerable LM3886 is still around. And I know STM makes amp chips too, so there are some low power options. But it seems that the golden days when National designers made miraculous analog ICs are waning, driven by a sensible marketing decision. Follow the money. Yah, right business answer but it sucks for audiophiles.
Hi guys,
after a long time of testing I hope to finally have found my problem using my "The Wire" amps...
I tested with an analogue, a regulated and an SMPS power supply and have always the same result. When biasing above 180mA the output signal begins to hum. The hum is getting louder when increasing the bias.
Same result using the 0R resistor between LME49830-GND and the FET-GND... and without it.
You can't image how long I searched for, as I can't image how this happens. Does anybody have an idea? Same results?
I hope I can fix it asap.
Thanks
Stammheim
after a long time of testing I hope to finally have found my problem using my "The Wire" amps...
I tested with an analogue, a regulated and an SMPS power supply and have always the same result. When biasing above 180mA the output signal begins to hum. The hum is getting louder when increasing the bias.
Same result using the 0R resistor between LME49830-GND and the FET-GND... and without it.
You can't image how long I searched for, as I can't image how this happens. Does anybody have an idea? Same results?
I hope I can fix it asap.
Thanks
Stammheim
Furthermore following information:
Both amps are connected to one ps, and when ONE is biased above 180mA, both speakers are humming. So I assume it seems to influence the GND.
Does your hum happen with just one circuit connected to one supply?
If it is good, has anyone here seen anyone make a discreet version of this chip that enthusiasts can make up themselves?
I've not noticed any comparisons made by people here, or else where, between amps made using these chips and various top quality amps? Are there some around?
If it is good, has anyone here seen anyone make a discreet version of this chip that enthusiasts can make up themselves?