Jacco,
Thanks, you are correct.
The 108/370 where earlier developed on the request to reduce device dimensions an ever ongoing requirement in the semiconductor industry.
The difference is, the 74/170 types in TO92 cases will be faced out and only the production of the smaller types 108/370 will continou.
Gerd
Thanks, you are correct.
The 108/370 where earlier developed on the request to reduce device dimensions an ever ongoing requirement in the semiconductor industry.
The difference is, the 74/170 types in TO92 cases will be faced out and only the production of the smaller types 108/370 will continou.
Gerd
Yes, an absolutely amazing world! And to think that FedEx, UPS, DHL and all the rest pickup and deliver more than 20 Million packages per day with mind boggling efficiency ... and this during a world wide recession. (UPS logistics is planning on seeing this traffic double over the next few years, recession or not!)
... and it is rare to see a frown on the delivery person's face!
I was just about to put an order in for two 300VA toroids, each with two secondaries of 0-18V when I re-read the BA-2 info. Nelson suggests for each channel 6 pairs of mosfets when a single power board contains 3 pairs. So if I am going to use just one board for each channel will I actually need a total of two 300VA toroids? What could I get away with?
Regards,
Chris
Regards,
Chris
What you can get away with is not the right approach to diy.
The question should be "What size transformer should I use to get the best sounding BA-2"
Don't underestimate the work involved in building an amp.
I have built several amps over a few years and none of them are in cases. I am halfway through the cases as we speak but it has taken me many hours more to do this than I expected.
If I were to put a dollar figure of about $40 an hour for my labour, it is not worth trying to save $100 here or there.
For me 300VA is a bare minimum. There will come a time when you might want to increase the bias or build another amp. If you go with the smallest transformer you can get away with you might find that you will need to buy bigger one later on. If that happens you won't be saving money you will be wasting money.
The question should be "What size transformer should I use to get the best sounding BA-2"
Don't underestimate the work involved in building an amp.
I have built several amps over a few years and none of them are in cases. I am halfway through the cases as we speak but it has taken me many hours more to do this than I expected.
If I were to put a dollar figure of about $40 an hour for my labour, it is not worth trying to save $100 here or there.
For me 300VA is a bare minimum. There will come a time when you might want to increase the bias or build another amp. If you go with the smallest transformer you can get away with you might find that you will need to buy bigger one later on. If that happens you won't be saving money you will be wasting money.
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Hi highfieldrebel,
you're right, D is the connection between the front-end and the output stage, where the signal goes through. I guess it's supposed to stand for drive or so. OUT is however not the output of the front-end but a feedback connection from the output of the output stage (which is, where you connect your loudspeakers to). Those declarations are maybe a bit confusing at the first look...
~ nightrush
you're right, D is the connection between the front-end and the output stage, where the signal goes through. I guess it's supposed to stand for drive or so. OUT is however not the output of the front-end but a feedback connection from the output of the output stage (which is, where you connect your loudspeakers to). Those declarations are maybe a bit confusing at the first look...
~ nightrush
Aha! So connect front-end and output at both "D" and "OUT", and take my loudspeaker out from the "OUT". Nice one, thanks NightrushHi highfieldrebel,
you're right, D is the connection between the front-end and the output stage, where the signal goes through. I guess it's supposed to stand for drive or so. OUT is however not the output of the front-end but a feedback connection from the output of the output stage (which is, where you connect your loudspeakers to). Those declarations are maybe a bit confusing at the first look...
~ nightrush
I have been looking for some cases with heatsinks either side for some time and I have seen some in Germany and Italy (ModU) but not in the UK. However, I have been talking with Les at Avondale audio audiophile amplifiers - audiophile power supplies - audiophile cables - DIY audio : avondale audio and he has just sold me an old case which had been hanging around his workshop, which will fit the bill (dimensions 440x310x130). He mentioned that it wouldn't be a problem to get some of these cases made up along the same dimensions but to make it worthwile he would need 10 orders. So if any of you need a case this might be your chance. I'm sure Les would also put in holes for IEC sockets and the like if asked.
I've posted the photo he sent me on the Gallery.
Regards,
Chris
I've posted the photo he sent me on the Gallery.
Regards,
Chris
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Well it looks like I'll go for two of the 300VA toroids but here is a question: will I hear a positive difference if I get them to fit electrostatic shielding between primary and secondary windings and a GOSS band or is this going to be overkill?
I have already been told that a metal cover to reduce RFI doesn't improve matters overall so I probably won't bother with that.
Regards,
Chris
I have already been told that a metal cover to reduce RFI doesn't improve matters overall so I probably won't bother with that.
Regards,
Chris
Is there any real advantage to black anodize the bracket that the power fets
(IRFP 240/9240) are mounted to, which in turn are bolted to the black anodized heat sinks. The problem I have is there isen't any place to get the parts anodized where I live. And I question if I do them myself if they would be any better for black body radiation than the clear aluminum. I will biase the 6 pair of FETS around 150ma to 200ma with supply of + - 50volts.
(IRFP 240/9240) are mounted to, which in turn are bolted to the black anodized heat sinks. The problem I have is there isen't any place to get the parts anodized where I live. And I question if I do them myself if they would be any better for black body radiation than the clear aluminum. I will biase the 6 pair of FETS around 150ma to 200ma with supply of + - 50volts.
anodizing is mostly an industrial way to avoid corosion, and improve looks
the rest is heresay and fashion
if it always stays in a dry place, no problem with the raw alu
but I wouldnt use alu bracket with classA anyway
it puts high demands on completely smooth and plane surfaces
which only very few heatsinks have
and the longer the bracket is, the worse it gets
the rest is heresay and fashion
if it always stays in a dry place, no problem with the raw alu
but I wouldnt use alu bracket with classA anyway
it puts high demands on completely smooth and plane surfaces
which only very few heatsinks have
and the longer the bracket is, the worse it gets
Hi JimM,
I can see why you would want to use a bracket first to attach your Mosfets to because drilling the exact number of holes in exactly the right positions directly into the heatsinks so as not to put any torque or force into the connected semiconductors when they are screwed in, is not going to be easy.
I had thought of it myself until the arguments such as cviller and tinnitus have espoused above, began to make themselves felt. I have been looking at the idea of spring loaded clips which are first affixed to the heatsink and which then fasten the semiconductors in place. However, I haven't found any clips with screw holes, they mostly clip into an indent already in a heatsink. However, I'm working on this and will let you know what I come up with. Most of these issues are linked to industrial practices of mass fabrication rather than the diy community unfortunately.
Regards,
Chris
I can see why you would want to use a bracket first to attach your Mosfets to because drilling the exact number of holes in exactly the right positions directly into the heatsinks so as not to put any torque or force into the connected semiconductors when they are screwed in, is not going to be easy.
I had thought of it myself until the arguments such as cviller and tinnitus have espoused above, began to make themselves felt. I have been looking at the idea of spring loaded clips which are first affixed to the heatsink and which then fasten the semiconductors in place. However, I haven't found any clips with screw holes, they mostly clip into an indent already in a heatsink. However, I'm working on this and will let you know what I come up with. Most of these issues are linked to industrial practices of mass fabrication rather than the diy community unfortunately.
Regards,
Chris
http://www.conrad.de/ce/de/overview/0205045/Transistor-Halteklammern-Haltefedern
if its good to use or not, I dont know
Hi tinitus,
German not that good although it looks like Kuhlung is heatsink maybe?
I saw this on AAVID Thermalloy:
http: //www.aavidthermalloy.com/products/maxclip/index.shtml
This is the 'Maxclip' system. Can't see how to implement it at present.
Incidentally, does one need to electrically insulate the Mosfets from the metal heatsink?
Regards,
Chris
German not that good although it looks like Kuhlung is heatsink maybe?
I saw this on AAVID Thermalloy:
http: //www.aavidthermalloy.com/products/maxclip/index.shtml
This is the 'Maxclip' system. Can't see how to implement it at present.
Incidentally, does one need to electrically insulate the Mosfets from the metal heatsink?
Regards,
Chris