About heatsinks, I have no idea what rating these have but I do have four pieces of them.
Size is 30cm x 20cm x 4cm which should be about 12" x 8" x 1.6". The "baseplate" is 1cm thick and there are 30 or so grooves/fins where 1/3 of the material is left.
Any chance that one sink is enough for one channel or should I play safe and use two sinks from start?
I have tried to add a pic but I seem to be retarded when it comes to computors and intenet.
/Peter
Size is 30cm x 20cm x 4cm which should be about 12" x 8" x 1.6". The "baseplate" is 1cm thick and there are 30 or so grooves/fins where 1/3 of the material is left.
Any chance that one sink is enough for one channel or should I play safe and use two sinks from start?
I have tried to add a pic but I seem to be retarded when it comes to computors and intenet.
/Peter
Attachments
Peter,
You can easily find out what rating they are. Simply attach a case style 20 or 50W resistor, for example 10-ohm, if possible via a copper plate to spread out the heat better. Then apply a known current and voltage and calculate the dissipation of the resistor. By simply measuring the temperature of the heatsink after 30-mins or so and determining the deltaT vs. the ambient temperature you can make a good guess of the heatsink's K/W rating.
Best regards,
Sander Sassen
http://www.hardwareanalysis.com
You can easily find out what rating they are. Simply attach a case style 20 or 50W resistor, for example 10-ohm, if possible via a copper plate to spread out the heat better. Then apply a known current and voltage and calculate the dissipation of the resistor. By simply measuring the temperature of the heatsink after 30-mins or so and determining the deltaT vs. the ambient temperature you can make a good guess of the heatsink's K/W rating.
Best regards,
Sander Sassen
http://www.hardwareanalysis.com
I am still surprised that nobody, i mean really nobody, can give us any details about the sounding of this amp.
Thats why i am going to build one myself.
I have now for 11 years the LFA-50 OA running in my hifiset, also an DIY amp published in the Elektor. It sounds like a angel (till today). Compared with commercial amps it was then times its value to the cost to built it. I am really surprised to read so many bad comment on this forum about this amp. Must be a taste question.
However, not to much discussion about his.
I just want to make everybody aware of the fact that i have trust
in the amp projects from Elektor. Even without hearing them. Because i vote for class A (not a tube fan) I have been waiting long for a new Class a project from Elektor like this ExtremA amp.
Now having more time off with my new job, i think it is time for a replacement amp for my hifiset. (updating my complete set)
So, who can provide me with a stereo set of PCB's for the ExtremA, or can tell me where to order.
Thats why i am going to build one myself.
I have now for 11 years the LFA-50 OA running in my hifiset, also an DIY amp published in the Elektor. It sounds like a angel (till today). Compared with commercial amps it was then times its value to the cost to built it. I am really surprised to read so many bad comment on this forum about this amp. Must be a taste question.
However, not to much discussion about his.
I just want to make everybody aware of the fact that i have trust
in the amp projects from Elektor. Even without hearing them. Because i vote for class A (not a tube fan) I have been waiting long for a new Class a project from Elektor like this ExtremA amp.
Now having more time off with my new job, i think it is time for a replacement amp for my hifiset. (updating my complete set)
So, who can provide me with a stereo set of PCB's for the ExtremA, or can tell me where to order.
This is a rather advanced and also expensive amp, not common DIY stuff. I think it will take a while but surely it will be built.madrigal said:I am still surprised that nobody, i mean really nobody, can give us any details about the sounding of this amp.
Thats why i am going to build one myself.
madrigal said:
It takes some time to build a suitable low thd+n pre-amplifier for the E-A if there's no feel to drive the power amps with an LM4562 based balanced pre.
The thing with the LFA50/150 is related to the CFP output in general, not aimed at criticising Andre Schmeets (or Elektruca salsa, those guys used to have admirable hearing)
Maybe one day someone will stick some A1360/C3423 in the front end of the LFA50 and load it with a triple darlington output stage.
I don't think this amp is more difficult to built then the LFA-50.
Almost everything is provided on the PCB. Of course you must work accurate with building an Amp and not to rush.
A small mistake is made easily. I remember that i also made one miner one building the LFA, one wrong transistor type solderd in.
Took me 2 days to solve. Building amps can be frustrating
Almost everything is provided on the PCB. Of course you must work accurate with building an Amp and not to rush.
A small mistake is made easily. I remember that i also made one miner one building the LFA, one wrong transistor type solderd in.
Took me 2 days to solve. Building amps can be frustrating
The amps are not completed yet.
I got hold of some surplus aluminum a week ago so I can now assemble the chassis.
I will build the monoblock chassis as two normal stereoamps.. that is the chassis will have a heatsink on each side. The two sinks in each chassi will be bridged by a thick slab of aluminum and he ExtremA boards will be mounted to these slabs. This way the powersupply and toroid will be placed below the PCB for minimum hum and noise. The slab will aslo make contact with the front or the back of the chassis for even more effective heat transport away from the slab. I think it will turn out fine.
I'll post some picks later on.
/Peter
I got hold of some surplus aluminum a week ago so I can now assemble the chassis.
I will build the monoblock chassis as two normal stereoamps.. that is the chassis will have a heatsink on each side. The two sinks in each chassi will be bridged by a thick slab of aluminum and he ExtremA boards will be mounted to these slabs. This way the powersupply and toroid will be placed below the PCB for minimum hum and noise. The slab will aslo make contact with the front or the back of the chassis for even more effective heat transport away from the slab. I think it will turn out fine.
I'll post some picks later on.
/Peter
Peter (aka Pan),
your heatsink looks like the SK 56 from Fischer Elektronik in Germany (www.fischerelektronik.de) - with a length of 200mm it will have 0.3K/W (if it's anodized in black - in 'naked' (bare) aluminum the value would be slightly higher or, in other words, slightly worse).
your heatsink looks like the SK 56 from Fischer Elektronik in Germany (www.fischerelektronik.de) - with a length of 200mm it will have 0.3K/W (if it's anodized in black - in 'naked' (bare) aluminum the value would be slightly higher or, in other words, slightly worse).
Thanks!
It's not identical but close enough I'd say so the 0.3K/W rating seems close. My sinks have 28 fins between the outer pair while the one in your link has 24.
Seems I made the right choice when I decided to go with two fins per channel.
I was to lazy to measure the way Sander proposed.
As mentioned earlier I'll bridge two heatsinks with a thick slab of alu. I think it will be enought and if the slab becomes to hot I'll mount yet another slightly smaller heatsink onto the slab. It will be an frankenamp but who cares as long as it pass all the goodies that's fed into it!
/Peter
It's not identical but close enough I'd say so the 0.3K/W rating seems close. My sinks have 28 fins between the outer pair while the one in your link has 24.
Seems I made the right choice when I decided to go with two fins per channel.
I was to lazy to measure the way Sander proposed.
As mentioned earlier I'll bridge two heatsinks with a thick slab of alu. I think it will be enought and if the slab becomes to hot I'll mount yet another slightly smaller heatsink onto the slab. It will be an frankenamp but who cares as long as it pass all the goodies that's fed into it!
/Peter
madrigal said:
I guess any modern low impedance type of good quality will do the job. Don't take my word for it though.
The amp is less sensitive for eventual cap problems due to constant current draw and the balanced differential design. PSRR is good.
I choosed good standard parts for my PCB's but if the amp is not transparent I'll look into parts swapping furhter down the road. No meaning IMO to waste money for audiophile parts if it doesn't effect the specific cricuit.
Hopefully I don't have to eat my hat after initial tests this spring.
/Peter
Does anybody of you ever ordered from this site:
http://hk.geocities.com/wkchenghk2000/orderformEng.htm
I am not sure if this stuff is real or cheap china imitation.
very cheap to me!
http://hk.geocities.com/wkchenghk2000/orderformEng.htm
I am not sure if this stuff is real or cheap china imitation.
very cheap to me!
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