Hello from Greece... willing to try a pure class A amp, and after the encouragement by some local guys who have built many pass amps, i have decided to give a try to such an amp.. based on matterials that i already have, i decided to give a try to Aleph 3. I think that 30w@8 and 60w@4 is more than enough for me... also can be done in a logical size...
I dont have much knowledge into electronics, measurments etc, but i have a lot of experience into building-assembling and following plans ..
So i have started gathering the extra matterials i need.. I ordered a 500VA Torroid transformer , with dual windings of 20-0-20 .. so 2 separate windings of 250VA each, encased in a metal box for better appearance.. it will be in my hands in a few days. I will post photos..
On the search for PCB 's i couldnt locate something more apropriate , so i ordered from ebay these ones. (hopefully they are ok)
Heatsinks i have 2 pieces of SK501 150 SA - these ones (around 0.34 K/W)
I have a question regarding PSU, In general i love to use good quality matterials. and I already have plenty of good quality of materials to build a classical PSU.. I was thinking to use per chanel 4x RUR3060 diodes to form one bridge + 2x 47.000/80v Mundorf m-lytic caps + 0.47mF MKP ... i see in various places that people use various types of psu. for example here i see this
Is this really critical? i mean to have dual bridges , chockes etc? i am asking because i wish to use matterials i already have..
Regarding the resistors, i see it requires 0.47ohm 3w.. What type? regular cement type? wirewound? metal film? or it doesnt make a difference?
Last but not least, transistors i guess that they should be matched, right?
Mounting requires anything special or the usual Mika insulators are ok?
I am sorry for the long post, but i will really apreciate any help given... Uppon receiving the various materials i have ordered I will update with photos of the construction.
I dont have much knowledge into electronics, measurments etc, but i have a lot of experience into building-assembling and following plans ..
So i have started gathering the extra matterials i need.. I ordered a 500VA Torroid transformer , with dual windings of 20-0-20 .. so 2 separate windings of 250VA each, encased in a metal box for better appearance.. it will be in my hands in a few days. I will post photos..
On the search for PCB 's i couldnt locate something more apropriate , so i ordered from ebay these ones. (hopefully they are ok)
Heatsinks i have 2 pieces of SK501 150 SA - these ones (around 0.34 K/W)
I have a question regarding PSU, In general i love to use good quality matterials. and I already have plenty of good quality of materials to build a classical PSU.. I was thinking to use per chanel 4x RUR3060 diodes to form one bridge + 2x 47.000/80v Mundorf m-lytic caps + 0.47mF MKP ... i see in various places that people use various types of psu. for example here i see this
An externally hosted image should be here but it was not working when we last tested it.
Is this really critical? i mean to have dual bridges , chockes etc? i am asking because i wish to use matterials i already have..
Regarding the resistors, i see it requires 0.47ohm 3w.. What type? regular cement type? wirewound? metal film? or it doesnt make a difference?
Last but not least, transistors i guess that they should be matched, right?
Mounting requires anything special or the usual Mika insulators are ok?
I am sorry for the long post, but i will really apreciate any help given... Uppon receiving the various materials i have ordered I will update with photos of the construction.
PSU - if you have easy way for using chokes , go for CLC ...... but no more than , say , 0R25 of choke Rdc
if not , CRC wit 0R1 WW 5W resistor will do the job perfectly
mosfets :
group at positive rail - all matched
group at negative rail - all matched
input mosfets (LTP) matched
power resistors in amp itself - use 3W MOX
if not , CRC wit 0R1 WW 5W resistor will do the job perfectly
mosfets :
group at positive rail - all matched
group at negative rail - all matched
input mosfets (LTP) matched
power resistors in amp itself - use 3W MOX
Well this cant be done.. i have only 4 pcs of 47.000/80v Mundorf mlytic’s..
If i dont do CRC whats the potential issue? Noise?
. Oh, and don't forget the obligatory blue indication LED.
Nah i dont like blue leds.. i prefer white! More high end!
Since you have not started I would suggest a newer build than the Aleph3. Boards are here.
Printed Circuit Boards – diyAudio Store
On these builds you will find detailed build guides as well. The F5 is among the easiest to build and is great with conventional speakers. The M2X does not require the hard to find J-fets to build but J-fets can be found here for the other builds. punkydawgs | eBay Stores
You will not regret the money spent for the Aleph 3 when finished. This is not to say that the Aleph 3 will not sound great but a build guide is worth the price of the boards you have bought.
Here you will find the power supply for most all the Pass builds. Scroll down to page 15. http://www.firstwatt.com/pdf/art_f6_baf.pdf
Just a suggestion from someone who has built over 10 of the Nelson Pass designs, the Aleph 30 being my first with Daniel boards vs the store ones.
As far as pre BA3 as a pre build, B1, LSK pre if you want to diy.
Printed Circuit Boards – diyAudio Store
On these builds you will find detailed build guides as well. The F5 is among the easiest to build and is great with conventional speakers. The M2X does not require the hard to find J-fets to build but J-fets can be found here for the other builds. punkydawgs | eBay Stores
You will not regret the money spent for the Aleph 3 when finished. This is not to say that the Aleph 3 will not sound great but a build guide is worth the price of the boards you have bought.
Here you will find the power supply for most all the Pass builds. Scroll down to page 15. http://www.firstwatt.com/pdf/art_f6_baf.pdf
Just a suggestion from someone who has built over 10 of the Nelson Pass designs, the Aleph 30 being my first with Daniel boards vs the store ones.
As far as pre BA3 as a pre build, B1, LSK pre if you want to diy.
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With this Fischer heat sink specified at 0.34k/w , aleph 3
will be too hot to touch.
Rule of thumb for Fischer heat sinks is to add 0.05k/w to specified value.
It means that for 100w power disipation per channel you will get around 39 degrees Celsius temperature rise compared to ambient temperature.
Its steel not danger for amplifier but uncomfortable to touch.
will be too hot to touch.
Rule of thumb for Fischer heat sinks is to add 0.05k/w to specified value.
It means that for 100w power disipation per channel you will get around 39 degrees Celsius temperature rise compared to ambient temperature.
Its steel not danger for amplifier but uncomfortable to touch.
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The Toshiba 2SJ201 / 2SK1530 transistors proved to be the best. The International Rectifier IRFP240 / IRFP9240 transistors ranked second. Though they are switching, nevertheless they are not much inferior to Toshiba transistors.
Hitachi 2SJ162 / 2SK1058 transistors are markedly non-linear and are not recommended for high-quality amplification.
The optimum of the rest current for them also turns out to be somehow vague.For IRFP240 / IRFP9240 transistors, the optimum rest current is 300 mA.
For 2SJ201 / 2SK1530 transistors, the optimal rest current is 200 ... 250 mA.
For 2SJ162 / 2SK1058 transistors, the optimal rest current is 120 ... 150 mA. http://www.electroclub.info/article/optimal_cmos_bias.htm
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