Compact Sized LME49810/11 +ThermalTrak Amp

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Eddie2

Member
Joined 2007
Hi everyone !
I also found the LME49830, and it looks very nice to me!
But I have a question: Could it be an idea, to use the IRFP630 ?
It can handle 400 V, 23 A, and 280 W.
I did not found a P-channel equivalent yet. Anyone an idea ?
If one wants to build something for 300...400 Watts, one can get 20V over the FET, while
drawing 10 Amps, meaning a dissipation of 200 Watts.
Any advices ?
Thanks in advance !
Eddie
 
panson_hk

panson_hk

Member
Joined 2005
pansonaudio.com
Kalle-Grabowski said:
Hi Panson,

first of all I'd like to thank you for your well documented and well engineered designs. That's quite a massive effort. I'm also impressed how good your PCBs look.

Perhaps there's still some room for improvements. ....
Click to expand...

Hi Kalle,

Thank you very much for your comment. The current compact PCB has definitely room to improve. Adding big caps might be difficult
in order to keep it compact, aimed for below 80 W power. I also wonder if this is a good idea to place "reservoir" cap onboard. I did that in some of previous/current layouts. But I also question myself to date if this is wise to do so. My latest preference is all massive reservoir caps very close to the rectifier diodes in order to have a very short path for huge charging current.

Local decoupling caps near output devices are definitely employed without doubt.
 
dirkwright

dirkwright

Member
Joined 2011
panson_hk said:
Hi Kalle,

Thank you very much for your comment. The current compact PCB has definitely room to improve. Adding big caps might be difficult
in order to keep it compact, aimed for below 80 W power. I also wonder if this is a good idea to place "reservoir" cap onboard. I did that in some of previous/current layouts. But I also question myself to date if this is wise to do so. My latest preference is all massive reservoir caps very close to the rectifier diodes in order to have a very short path for huge charging current.

Local decoupling caps near output devices are definitely employed without doubt.
Click to expand...

What about on board voltage supply regulators for the chip? I was thinking of replacing C10 and C11 with zener diodes and scaling R13 and R14 accordingly. That would be a simple regulator right there.

Also, what kind of transistor do we use for the Vbe multiplier?

It might not make much difference, but C8 should be a smaller 0.1uF MLC or film type, not a big electrolytic.

Otherwise, thanks for your hard work!

I'm going to use low ESR electrolytics ($$$) for the power supply board.
 
A

atupi

Member
Joined 2010
Panson i see all the measurements made for 8ohm speakers. I intend to build a low power version (50w). One pair of thermaltrack's would be enough ? Are needed some more adjustments ?
I need more than 2pcb's from your website "New Compact 4981x ThermalTrak Amplifier Board " ?
 
panson_hk

panson_hk

Member
Joined 2005
pansonaudio.com
dirkwright said:
What about on board voltage supply regulators for the chip? I was thinking of replacing C10 and C11 with zener diodes and scaling R13 and R14 accordingly. That would be a simple regulator right there.

Also, what kind of transistor do we use for the Vbe multiplier?

It might not make much difference, but C8 should be a smaller 0.1uF MLC or film type, not a big electrolytic.

Otherwise, thanks for your hard work!

I'm going to use low ESR electrolytics ($$$) for the power supply board.
Click to expand...

Hi,

You can add zener diodes as simple regulator. If I were adding a regulator for the front end, I will use linear regulator.

Do you use conventional output devices instead of ThermalTrak? Vbe multiplier can be MJE15030.

Why do you use small cap for C8?
 
panson_hk

panson_hk

Member
Joined 2005
pansonaudio.com
atupi said:
Panson i see all the measurements made for 8ohm speakers. I intend to build a low power version (50w). One pair of thermaltrack's would be enough ? Are needed some more adjustments ?
I need more than 2pcb's from your website "New Compact 4981x ThermalTrak Amplifier Board " ?
Click to expand...

Hi, One pair ThermalTrak NJL3281D/1302D is enough for 50 W / 8 Ohms. Very safe for driving reactive loads as well. You need to adjust bias setting, nothing more. Are you doing stereo amp?
 
dirkwright

dirkwright

Member
Joined 2011
panson_hk said:
Hi,

You can add zener diodes as simple regulator. If I were adding a regulator for the front end, I will use linear regulator.

Do you use conventional output devices instead of ThermalTrak? Vbe multiplier can be MJE15030.

Why do you use small cap for C8?
Click to expand...

Well, I'd prefer a linear regulator as well but that would be messy to add to the board. I prefer neat and orderly over messy and complicated.

I'm going to use the output transistors that you recommend, which I guess are the Thermal Trak. Are you saying that if I use the TT, outputs I don't need a Vbe multiplier? I'm not very experienced with all of this so pardon my confusion.

As for C8, bypassing a zener diode in a simple regulator circuit with a capacitor usually has the function of shorting the high frequency noise from the zener to ground. A big electrolytic is going to have too much inductance at high frequencies to effectively shunt the zener noise to ground. Normally, a small ceramic or mica capacitor is better at this kind of function. This may not be a big deal in the +5volt circuit but I'm just stating generalities here.
 
A

atupi

Member
Joined 2010
panson_hk said:
Hi, One pair ThermalTrak NJL3281D/1302D is enough for 50 W / 8 Ohms. Very safe for driving reactive loads as well. You need to adjust bias setting, nothing more. Are you doing stereo amp?
Click to expand...

Yes i want a stereo version for listening on medium audio levels in my livingroom.
Please be aware that my speakers are 4ohm bookshelfs.
If it's suitable i would like to reuse a toroid transformer 2x40V big enough.
 
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