Hello M. Pass and everyone,
M. Pass said "One of the aims of these articles is to get people to build amplifiers", ok, so lets do (try) it.
First project, I did not read the complete tread about it but I am shure you won´t kill me if I ask again the same questions.
English is not my native language, so sorry in advance.
I had opportunity to buy some c.villers PCB of the F5, so that´s why I am here.
My first question concern the power supply.
I have 2 really big Transformer of 2 x 6,3v/9a each.
The two 6,3v chained would give something around 12,6V/ and lots of amp (how many, good question).
Is it possible to use them and to run the F5 with lower voltage?
thanks in advance.
Vincent
M. Pass said "One of the aims of these articles is to get people to build amplifiers", ok, so lets do (try) it.
First project, I did not read the complete tread about it but I am shure you won´t kill me if I ask again the same questions.
English is not my native language, so sorry in advance.
I had opportunity to buy some c.villers PCB of the F5, so that´s why I am here.
My first question concern the power supply.
I have 2 really big Transformer of 2 x 6,3v/9a each.
The two 6,3v chained would give something around 12,6V/ and lots of amp (how many, good question).
Is it possible to use them and to run the F5 with lower voltage?
thanks in advance.
Vincent
Hi Vincent
my experience with the "Mini F5" (eg lower voltage) showed me not to use the IRFP's but 2SK2013/2SJ313 paralleled.
Your trannies will be fine for this solution
Look Juma's thread about the 2SK2013/2SJ313 F5 http://www.diyaudio.com/forums/pass-labs/168040-f5-2sk2013-2sj313.html
Franz
vince HH,
connecting your transformers in series makes an arrangement of 2 x 12.6 V AC / 9 A which will give you about +/-15V DC after rectification and under load. As Franz Gysi said, the 2sk2013/2sj313 MOSFETs will behave much better with such a low voltage than IRFP parts. You can expect the voltage swing of about 12Vpeak at the amp's output and that will cause each channel to draw 3Apeak under 4 Ohm load. So, it leaves enough headroom - you can have healthy 9W RMS at 8 Ohms or 18W RMS at 4 Ohms load per channel with those transformers. If that suits your needs, go ahead...
Und achte nicht auf den schadenfreundigen
connecting your transformers in series makes an arrangement of 2 x 12.6 V AC / 9 A which will give you about +/-15V DC after rectification and under load. As Franz Gysi said, the 2sk2013/2sj313 MOSFETs will behave much better with such a low voltage than IRFP parts. You can expect the voltage swing of about 12Vpeak at the amp's output and that will cause each channel to draw 3Apeak under 4 Ohm load. So, it leaves enough headroom - you can have healthy 9W RMS at 8 Ohms or 18W RMS at 4 Ohms load per channel with those transformers. If that suits your needs, go ahead...
Und achte nicht auf den schadenfreundigen
F5 playing music
Finally the F5 is connected up to speakers and a input source through my Yamaha C-2 preamp. Working beautifully. No noise, no hum, no distortion as far as I can hear with my ears. Right now playing music with my old speakers. Once I get confidence, I will connect to my Fostex back loaded horns.
Cheers.
Finally the F5 is connected up to speakers and a input source through my Yamaha C-2 preamp. Working beautifully. No noise, no hum, no distortion as far as I can hear with my ears. Right now playing music with my old speakers. Once I get confidence, I will connect to my Fostex back loaded horns.
Cheers.
Hi,
I had a look on Juma´s thread but to be honest, I understand nothing.
I have seen the schematic and I think that I would be able to copy it. But at the moment and as a first project, I would prefer to stay on the normal way.
I will search for the appropriate transformer (18V/400va)
For my knowledge, If I plug in serie a 6,3V/9A with an other 6,3V/9A, I obtain 12,6V but do I have 9A or 18A available?
Regarding the PSU of the F5, Nelson indicate capas rated at 25V but many people use capas rated at 35V.
I have possibility to have some Panasonic for a good price rated at 25V.
Is that ok?
Thanks,
Vincent
ps for Juma: I am french and not so good with german.
I had a look on Juma´s thread but to be honest, I understand nothing.
I have seen the schematic and I think that I would be able to copy it. But at the moment and as a first project, I would prefer to stay on the normal way.
I will search for the appropriate transformer (18V/400va)
For my knowledge, If I plug in serie a 6,3V/9A with an other 6,3V/9A, I obtain 12,6V but do I have 9A or 18A available?
Regarding the PSU of the F5, Nelson indicate capas rated at 25V but many people use capas rated at 35V.
I have possibility to have some Panasonic for a good price rated at 25V.
Is that ok?
Thanks,
Vincent
ps for Juma: I am french and not so good with german.
Hi Vince,
the 9Aac is the maximum current that can continuously be passed through any and every secondary without overheating the transformer. If the specification is for regulation limiting then that is the maximum AC current to meet the regulation specification.
Now when you series connect the secondaries the same current must pass through both secondaries. That leaves your current limit at the same 9Aac.
Note, this is an AC specification, where the transformer is loaded with a resistance, not loaded with a rectifier and capacitor input filter.
the 9Aac is the maximum current that can continuously be passed through any and every secondary without overheating the transformer. If the specification is for regulation limiting then that is the maximum AC current to meet the regulation specification.
Now when you series connect the secondaries the same current must pass through both secondaries. That leaves your current limit at the same 9Aac.
Note, this is an AC specification, where the transformer is loaded with a resistance, not loaded with a rectifier and capacitor input filter.
Download the F5 guide by http://viller.eu/audio/2009jan_gbf5/gbf5_guide.pdf by cviller (who is a member here), it contains illustrations of BC550/560 and ZTX550/450
Hi, they have a surge rated at 32VDc but I have checked more in detail the proposal (ebay) and they are from 2001.
They are sold for 12€ (around 15$) the 10.
So if it is not that critical, as my budget is not that high, I will give a go for this one and improve later on.
http://www.panasonic.com/industrial/components/pdf/pic_ts-ha_dne.pdf
Vincent
They are sold for 12€ (around 15$) the 10.
So if it is not that critical, as my budget is not that high, I will give a go for this one and improve later on.
http://www.panasonic.com/industrial/components/pdf/pic_ts-ha_dne.pdf
Vincent
Can I mount power MOSFETS different heatsinks
Hi,
I am struggling to get a longish heatsinks with fins aligned vertically for my F5. I am able to get 7" width extrusions, which I am planning to cut them up and place side by side to get a vertical fin alignment to get a total width of 14" for each side of the amp.
My question is: Can I mount IRFP240 and IRFP9240 of one channel on these two physically separate pieces? While the heatsinks may be placed side by side, there would a small gap and heat flow between the two pieces may not be uniform.
Will this impact the performance of F5?
The other option is to use horizontally aligned fins, of which I can get lengths of my specification.
Thanks in advance.
Anil
Hi,
I am struggling to get a longish heatsinks with fins aligned vertically for my F5. I am able to get 7" width extrusions, which I am planning to cut them up and place side by side to get a vertical fin alignment to get a total width of 14" for each side of the amp.
My question is: Can I mount IRFP240 and IRFP9240 of one channel on these two physically separate pieces? While the heatsinks may be placed side by side, there would a small gap and heat flow between the two pieces may not be uniform.
Will this impact the performance of F5?
The other option is to use horizontally aligned fins, of which I can get lengths of my specification.
Thanks in advance.
Anil
Same problem here. Can't seem to find the right heatsinks. I think it's expensive to make such wide extrusions because yield is lower and the dies are expensive.
I'd think you would have better thermal stability with one heatsink but i'm not positive. Maybe tie the two pieces togther with a heat spreader plate.
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I have seen quite a number of pictures in the earlier posts where people have used one heatsink per output device. Wonder what the effect of such an arrangement is in terms of thermal stability and bias balance.
Hi Anil, look at Peter Daniel's implementation with two Conrad heatsinks on this thread. I had the same question and was working on a two-sink layout, but eventually I managed to get the sinks locally (one of which Ali is talking to you about - I've been advising him on the heatsink selection).
If you keep them close together and have a metal bar joining the sinks you can ensure sufficient thermal coupling to keep the offset under control. You can also use an 8" length of 8mm thick copper bar to mount the devices, and secure the bar to the sinks. The temperature of the power transistor has some correlation to the operating point, and relative thermal and electrical balance between the channels determines the output offset.
In the case of the profile in the attachment, a single 10" profile is what I use for one F5 channel and it works pretty well, in winters I get a maximum temperature of 45 degrees, and in summer it goes up to maybe 50-55. I believe Ali has recommended this as the 7" profile you are talking about.
The amps don't look like this anymore, this was a testing setup only but you get the idea.
Horizontal fins is not a great idea, unless of course you can get something like the First Watt originals (which are patented AFAIK). Long heatsinks are not necessarily much better, the further away the edges go from the heat source, the less effective it becomes. You need a lot of mass and sufficient surface area within close distances from the source of the heat.
Good Luck. Finding heatsinks in this country is very difficult - almost impossible to get anything more than 8" wide. Ali is working on some chipamp cases for me using some 8" width sinks, even cutting them to length was an issue, let alone extruding them.
If you keep them close together and have a metal bar joining the sinks you can ensure sufficient thermal coupling to keep the offset under control. You can also use an 8" length of 8mm thick copper bar to mount the devices, and secure the bar to the sinks. The temperature of the power transistor has some correlation to the operating point, and relative thermal and electrical balance between the channels determines the output offset.
In the case of the profile in the attachment, a single 10" profile is what I use for one F5 channel and it works pretty well, in winters I get a maximum temperature of 45 degrees, and in summer it goes up to maybe 50-55. I believe Ali has recommended this as the 7" profile you are talking about.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The amps don't look like this anymore, this was a testing setup only but you get the idea.
Horizontal fins is not a great idea, unless of course you can get something like the First Watt originals (which are patented AFAIK). Long heatsinks are not necessarily much better, the further away the edges go from the heat source, the less effective it becomes. You need a lot of mass and sufficient surface area within close distances from the source of the heat.
Good Luck. Finding heatsinks in this country is very difficult - almost impossible to get anything more than 8" wide. Ali is working on some chipamp cases for me using some 8" width sinks, even cutting them to length was an issue, let alone extruding them.