Not so lucky here I'm afraid.
Still, I've put Nelson's power supply arrangement in my Exposure 18s monoblocks using Schottky diodes and the result is fantastic. Better image definition, space around instruments illuminated etc, etc. Be interesting to compare the sounds when I finally build the BA-2.
Regards,
Chris
Still, I've put Nelson's power supply arrangement in my Exposure 18s monoblocks using Schottky diodes and the result is fantastic. Better image definition, space around instruments illuminated etc, etc. Be interesting to compare the sounds when I finally build the BA-2.
Regards,
Chris
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If you are talking about the original chassis, given out at The Festival, some had 6 pairs per channel and others had 4 pairs. In the BA-2 article I believe Nelson says that 2-3 pairs would work well for most people, though the schematic shows the 6 pairs.
So after way too much discussion,we decided on each output board being 3 pairs in one row, and as you mention, if you want more, use 2 Output Boards per channel
Ragarding heat dissapition – have got this right or have I got it all backwards?
The BA2 article is saying that two channels will dissipate as much as 300 W. But doesn’t that refer to the 6 pairs per channel output board? I have only 3 pairs per channel output boards. Wouldn’t that give me half the heat dissipation? 300 W/12*6=150 W
Divided on two heatsinks 150/2=75 W
Then I need to loose 75 W per heatsink. I calculate with an ambient temperature of 25 C and the heatsink can’t be hotter than 65 C at the spot where the transistor is mounted. 65-25=30 C.
The thermical resistance must then be les or equal to 30/75=0.4 C/W.
I realise that calculating with an ambient temperature of 25 C might give to small margins.
This is the kit I`m having on my desk an referring to above.
An externally hosted image should be here but it was not working when we last tested it.
Kind regards
/Fredrik
Hi Forsman
the most important point is that the amount of heat you dissipate can be reduced if you reduce the bias on the MOSFETs, or use fewer MOSFET pairs.
Now, to your question: 65-25=40, not 30. So you might think the 0.4 K/W is excessive. But the supplier cannot know the distribution of heat sources of all his customers, so he must test/model with some 'ideal' distribution. So, there is a correction of 25 to 50 % necessary for real world heat distributions (I think I'm quoting AndrewT here, apologies Andrew if I'm misremembering). Anyway, this means that 0.4 K/W is looking like a good number again. If the heatsink gets to hot, back off the bias. BTW 60 degrees is really hot to the touch.
Steve
the most important point is that the amount of heat you dissipate can be reduced if you reduce the bias on the MOSFETs, or use fewer MOSFET pairs.
Now, to your question: 65-25=40, not 30. So you might think the 0.4 K/W is excessive. But the supplier cannot know the distribution of heat sources of all his customers, so he must test/model with some 'ideal' distribution. So, there is a correction of 25 to 50 % necessary for real world heat distributions (I think I'm quoting AndrewT here, apologies Andrew if I'm misremembering). Anyway, this means that 0.4 K/W is looking like a good number again. If the heatsink gets to hot, back off the bias. BTW 60 degrees is really hot to the touch.
Steve
oops, thats what happens when I dont use the calculator even for simpler things...Thanks
/Forsman
Beware!
I ordered the BA-2 boards and am having them sent via USPS international. I used their Tracking system and asked them to email me for updates. Last Friday I received an email supposedly from USPS saying my parcel had been returned to a post office due to incorrect address and click here for details. When I clicked on this I had 'Palladium' software downloaded onto the computer and the result has been £140 to repair the computer. I assume the parcel is still on its way but beware to any of you who might face this problem.
Regards,
Chris
I ordered the BA-2 boards and am having them sent via USPS international. I used their Tracking system and asked them to email me for updates. Last Friday I received an email supposedly from USPS saying my parcel had been returned to a post office due to incorrect address and click here for details. When I clicked on this I had 'Palladium' software downloaded onto the computer and the result has been £140 to repair the computer. I assume the parcel is still on its way but beware to any of you who might face this problem.
Regards,
Chris
Always go to the USPS site and enter the tracking number manually.
The USPS "small flat rate box", and "flat rate envelope" DO NOT allow tracking -- but they will tell you when the package is received into the US Postal system for dispatch. I've found that tracking USPS Express Mail is pretty useless once the parcel leaves the US, but they manage to get to most destinations in a couple of days.
The USPS "small flat rate box", and "flat rate envelope" DO NOT allow tracking -- but they will tell you when the package is received into the US Postal system for dispatch. I've found that tracking USPS Express Mail is pretty useless once the parcel leaves the US, but they manage to get to most destinations in a couple of days.
Chris,
Thanks for your order, and also thanks for posting here to alert everyone else to be careful about this.
I'm very sorry you got infected by that email (that obviously didn't come from either us or USPS). Trojans spread through emails purporting to be from places of trust such as USPS, banks, Paypal and more are becoming increasingly common as the bad guys try to create a feeling of trust that will get you to click on a link.
Unfortunately, it looks like you just happened to be expecting something from USPS at the same time you got this random trojan spam which was especially bad timing.
More details (looks like a similar thing): Fake United States Postal Service Emails Distribute Trojan Downloader - Softpedia
The only half decent advice, as annoying as it is, is never to click on a link in any email that purports to come from a place of trust such as paypal, banks, USPS, the IRS, etc...
Thanks for your order, and also thanks for posting here to alert everyone else to be careful about this.
I'm very sorry you got infected by that email (that obviously didn't come from either us or USPS). Trojans spread through emails purporting to be from places of trust such as USPS, banks, Paypal and more are becoming increasingly common as the bad guys try to create a feeling of trust that will get you to click on a link.
Unfortunately, it looks like you just happened to be expecting something from USPS at the same time you got this random trojan spam which was especially bad timing.
More details (looks like a similar thing): Fake United States Postal Service Emails Distribute Trojan Downloader - Softpedia
The only half decent advice, as annoying as it is, is never to click on a link in any email that purports to come from a place of trust such as paypal, banks, USPS, the IRS, etc...
At last the PCBs have arrived. Whosoever understands the mysteries of the postal service may indeed inherit the world!
I have asked this before but I didn't really understand the answer although it is clearer now I have had time to study the PCBs.
I take it that the wiring pathway is input into the front end board (In+, GND, In-) then from the same board V-, V+, D and OUT, are connected to the corresponding points on the bias board. GND of the front end is connected to GND of the power board.
From the other side of the bias board V-, V+, CTL+, CTL-, and OUT are connected to the corresponding points on the Output board.
Questions are.
The output to the loudspeaker post would be from OUT on the power board would it?
I take it that the main power supply input need only be connected once but does it matter where? To the front end board or to the power board?
Regards,
Chris
I have asked this before but I didn't really understand the answer although it is clearer now I have had time to study the PCBs.
I take it that the wiring pathway is input into the front end board (In+, GND, In-) then from the same board V-, V+, D and OUT, are connected to the corresponding points on the bias board. GND of the front end is connected to GND of the power board.
From the other side of the bias board V-, V+, CTL+, CTL-, and OUT are connected to the corresponding points on the Output board.
Questions are.
The output to the loudspeaker post would be from OUT on the power board would it?
I take it that the main power supply input need only be connected once but does it matter where? To the front end board or to the power board?
Regards,
Chris
You're right, In+, GND an IN- are connected to the input plug of your amp. V-, GND and V+ are for the Supply Voltages. OUT and D go to the Biasing board, D carries the signal, OUT is for some feedback loop.
You will want to connect all pins on one side of your bias-board to all pins on one side of the output board. V+ and V- are as always for the supply voltages, OUT is the output of your Amplifier. Ctl+ and Ctl- don't have to be connected to anything else.
As the power board gets most of the power, you will want to primarily connect the power supply to it. The Frontend-board doesn't consume very much power, you can either attach it to the psu directly or to the unused pins of your power board.
Best Regards, nightrush
Thanks Nightrush,
As a matter of interest have you used a 10uF polypropylene cap as suggested by Nelson on the front end or a 10uF electrolytic such as an Elna Silmic?
My instinct is to use the polypropylene but the size could be an issue. I do like the Elnas but they don't always work. They certainly didn't with the BA-2 power supply where I much preferred a 10uF polyprop to a similarly rated SilmicII. The latter sounded a little ragged or indistinct when used with an exposure monoblock 16.
Regards,
Chris
As a matter of interest have you used a 10uF polypropylene cap as suggested by Nelson on the front end or a 10uF electrolytic such as an Elna Silmic?
My instinct is to use the polypropylene but the size could be an issue. I do like the Elnas but they don't always work. They certainly didn't with the BA-2 power supply where I much preferred a 10uF polyprop to a similarly rated SilmicII. The latter sounded a little ragged or indistinct when used with an exposure monoblock 16.
Regards,
Chris
