XELB said:
m0tion said:
The boards are based off of the design the Carlos Filipe (carlosfm), which was built by other members with good results.
I will do a comparison myself when I get the new pcbs.
EDIT: finally hit 3 pages on this thread
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Brian
XELB said:I will wait for your report/review.
But in the meanwhaile, count one PSU PCB and two LM3886 PCB for me
You will sell it without the parts, correct ?
Yes, I have the items on my order page on chipamp.com
I will be selling:
- LM3886 dual mono pcb set (2 amp and 2 power supply boards)
- LM3886 stereo pcb set (2 amp and 1 power supply boards)
- LM3886 dual mono kit
- LM3886 stereo kit
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Brian
I ordered the PCBs for the LM3886 project, and have started accepting pre-orders on the website:
http://www.chipamp.com
The pricing is $15 higher than the LM3875 kits due to the extra power supply components ($30 extra for dual mono since there are 2 power supply boards).
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Brian
http://www.chipamp.com
The pricing is $15 higher than the LM3875 kits due to the extra power supply components ($30 extra for dual mono since there are 2 power supply boards).
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Brian
I created more shipping options for international orders, for those only ordering pcbs, and I refunded the extra shipping for those who already submitted orders for pcbs only. Make sure to read over the shipping options carefully and selecting the appropiate one. I am sorry if it is confusing.
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Brian
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Brian
Brian, can you comment on the max current rating of you power supply board (rough estimate). To me it looks like a usefull candidate for a 'generic' power supply, also for different amps (class D UcD modules for instance). But in that case it would be nice to now if it will hold up to say 10A.
Rob
Rob
>Any ideas on a recommended tranny for this amp?
what ever the voltage, to take the advatage of higher current output of LM3886, I think it should be able to sustain 6Amp for each AC secondary output...
So for 18VAC, it would be 2x18x6 == 216VA == 225VA for each channel or 450VA for dual channel.
That also means that for 25VAC secondary it would be 2x25x6 == 300VA for each channel or 600VA for dual channel.
Regards,
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David
what ever the voltage, to take the advatage of higher current output of LM3886, I think it should be able to sustain 6Amp for each AC secondary output...
So for 18VAC, it would be 2x18x6 == 216VA == 225VA for each channel or 450VA for dual channel.
That also means that for 25VAC secondary it would be 2x25x6 == 300VA for each channel or 600VA for dual channel.
Regards,
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David
Re: power supply
The limiting factor for the power supply board is the heat dissipation for the diodes. Without heatsinks, 1 board can power 2 channels of the gainclone without the diodes getting too hot. I have not taken any measurement to see how much current this is. If you were to put heatsinks on the diodes, the power supply board would work for most applications. Also, I am currently not selling the power supply boards seperately from the pcb sets.
National has some suggestions on power supply voltages in the LM3886 data sheet:
"68w cont. avg. output power into 4 ohms at Vcc = +/- 28Vdc
38w cont. avg. output power into 8 ohms at Vcc = +/- 28Vdc
50w cont. avg. output power into 8 ohms at Vcc = +/- 35Vdc"
I attached a graph from the datasheet as well.
Link to datasheet:
http://www.national.com/ds.cgi/LM/LM3886.pdf
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Brian
MIB said:
The limiting factor for the power supply board is the heat dissipation for the diodes. Without heatsinks, 1 board can power 2 channels of the gainclone without the diodes getting too hot. I have not taken any measurement to see how much current this is. If you were to put heatsinks on the diodes, the power supply board would work for most applications. Also, I am currently not selling the power supply boards seperately from the pcb sets.
mantisory said:
National has some suggestions on power supply voltages in the LM3886 data sheet:
"68w cont. avg. output power into 4 ohms at Vcc = +/- 28Vdc
38w cont. avg. output power into 8 ohms at Vcc = +/- 28Vdc
50w cont. avg. output power into 8 ohms at Vcc = +/- 35Vdc"
I attached a graph from the datasheet as well.
Link to datasheet:
http://www.national.com/ds.cgi/LM/LM3886.pdf
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Brian
Attachments
To mOtion : That's the question, but in most amp is transformer dimensioned to nominal power consumption. " Overkilled " transformer bring although little bit better sound, but difference is not great and 225 VA transformer with secondary voltage 2*18 V, declared for one channel, IS " overkilled "
Well, my current plan is (2) 2x22vac 400va transformers for 6 channels (one for every three channels). So, that comes out to 133VA a channel at 22VAC. What I'm wondering (and I know this depends on what the impedence of what the amp is driving) is how you would calculate the power requirements for this particular setup.
To homer : In my amp with LM 4780 I have 200 VA toroidal transformer with 2*25 V AC. Output power is ( by one channel driven ) little bit below 80 W/ 4 ohm. By both channels driven is it 2*60 W / 4 Ohm, 2*45 W/ 8 Ohm and in bridge configuration 120 W / 8 Ohm. With cca 300 VA transformer and the same voltage, you can to get app. 10 - 15 % more wattage, but it will be not for this chip safety, so you must use lower voltage.
Re: power supply
I'm too lazy to do a forum search for you guys, but I'd bet hard cash this has been covered here before more than once.
Nat Semi's datasheet for the chip may also have some useful info. You wouldn't want to build one of these amps without knowing that datasheet from front to back.
mantisory said:
m0tion said:
homer09 said:
I'm too lazy to do a forum search for you guys, but I'd bet hard cash this has been covered here before more than once.
Nat Semi's datasheet for the chip may also have some useful info. You wouldn't want to build one of these amps without knowing that datasheet from front to back.
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