One question. I had to desolder r8 as I put the wrong value in it and it looks like the pad has lifted ever so slightly. I have tried to attach some photos but it was hard to get a close up with my phone camera. Is this still workable? Or will I have to replace the board?
Thanks
Thanks
Attachments
Q re transformer voltage
I just received the Aleph J boards and 2 sets of the Universal PS boards from the DiyAudio store. I am about to order a transformer but have a couple of questions before I place the order.
I am building a pair of mono blocks for use with 4 ohm speakers. 2PicoDumbs suggests that to get the most out of the Aleph with 4 ohm speakers I should plan on biasing it at 2 to 3 amps. I have calculated that for any given temperature at the heatsink, for every volt I drop the PS, I can raise the bias by .1 amp. I am thinking of setting the voltage at around +/- 19 or 20 volts.
From what I have seen, it appears that most are using 18-0-18 transformers and getting around 24-25 volts. However, it also appears that some have found that with load the voltage is reduced to around 21. If the voltage with the 18V transformer is around 24 or 25, I could raise the bias by .5 without increasing the heatsink temperature if I dropped the voltage to 20. That would seem to be worthwhile. However, if the voltage will be 21 with load, it seems like dropping the voltage would be more trouble than it is worth. Could someone let me know what the actual working voltage is with the 18V transformer? I have not been able to find a definitive answer in the forum. I plan on using a 200 or 250 VA transformer with each board with the standard build (8 caps of 15,000 uF each on each board; R1 through R8 are .47 ohms; bridge rectifiers).
If the voltage will be 24 or 25 with an 18V transformer, would I be better off using a 15-0-15 transformer or using the 18Volt transformer and reducing the 24 or 25 volts with resistors?
Thank you.
I just received the Aleph J boards and 2 sets of the Universal PS boards from the DiyAudio store. I am about to order a transformer but have a couple of questions before I place the order.
I am building a pair of mono blocks for use with 4 ohm speakers. 2PicoDumbs suggests that to get the most out of the Aleph with 4 ohm speakers I should plan on biasing it at 2 to 3 amps. I have calculated that for any given temperature at the heatsink, for every volt I drop the PS, I can raise the bias by .1 amp. I am thinking of setting the voltage at around +/- 19 or 20 volts.
From what I have seen, it appears that most are using 18-0-18 transformers and getting around 24-25 volts. However, it also appears that some have found that with load the voltage is reduced to around 21. If the voltage with the 18V transformer is around 24 or 25, I could raise the bias by .5 without increasing the heatsink temperature if I dropped the voltage to 20. That would seem to be worthwhile. However, if the voltage will be 21 with load, it seems like dropping the voltage would be more trouble than it is worth. Could someone let me know what the actual working voltage is with the 18V transformer? I have not been able to find a definitive answer in the forum. I plan on using a 200 or 250 VA transformer with each board with the standard build (8 caps of 15,000 uF each on each board; R1 through R8 are .47 ohms; bridge rectifiers).
If the voltage will be 24 or 25 with an 18V transformer, would I be better off using a 15-0-15 transformer or using the 18Volt transformer and reducing the 24 or 25 volts with resistors?
Thank you.
I'm glad this tip came in handy! I searched my local hardware store for about 30-45 mins before I stumbled on those. Good looking build too, enjoy!
About C6 and C7 (the polypropoline film bypass capacitors for C2 and C3): include or omit?
They do not appear in the Papa's Aleph J schematic. They do appear in the latest schematic for the DIYAudioStore Aleph J boards. The online debates about using film caps to bypass electrolytic caps seem endless. Thoughts from you experts?
As I'm trying to build a n00bs guide, I'm inclined to omit them unless there's a good case for them, since omitting them would mean 8 fewer soldering joints to potentially mess up. The caps we're using for C2 and C3 are Elna Silmic 2, which seem like quality electrolytics, perhaps making a film bypass less necessary?
And, if C6 and C7 are included, any reason this wouldn't be a good part choice
MKP2F033301M00JSSD WIMA | Mouser
(Wima, 0.33uf, 250V, 5mm lead spacing)?
They do not appear in the Papa's Aleph J schematic. They do appear in the latest schematic for the DIYAudioStore Aleph J boards. The online debates about using film caps to bypass electrolytic caps seem endless. Thoughts from you experts?
As I'm trying to build a n00bs guide, I'm inclined to omit them unless there's a good case for them, since omitting them would mean 8 fewer soldering joints to potentially mess up. The caps we're using for C2 and C3 are Elna Silmic 2, which seem like quality electrolytics, perhaps making a film bypass less necessary?
And, if C6 and C7 are included, any reason this wouldn't be a good part choice
MKP2F033301M00JSSD WIMA | Mouser
(Wima, 0.33uf, 250V, 5mm lead spacing)?
Up and running part 4 The end
Got my 2,2mH inductors hooked up yesterday,
As suspected it was quite a step up from initial setup without inductors.
Now its runnning CLC consisting of:60000uF - 2,2mH air coils in epoxy - 52800uf.
With the inductors in place the sound went anoter step darker and more quiet.
Just my cup of tea.
Love it,
thank you all for all the good info.
Got my 2,2mH inductors hooked up yesterday,
As suspected it was quite a step up from initial setup without inductors.
Now its runnning CLC consisting of:60000uF - 2,2mH air coils in epoxy - 52800uf.
With the inductors in place the sound went anoter step darker and more quiet.
Just my cup of tea.
Love it,
thank you all for all the good info.
Attachments
@6L6, saw this post (#4784), tried it and it somehow fixed the the veiled/dull sound I was getting from my Aleph J. I didn’t have to warm it up for an hour to hear the change. Yes, it sounds crazy, but do you have an explanation how reversing speaker lead could change the sound? Thanks.
FIRST WATT
read about H2 an Korg B1, then read everything else
point is in phase flip of dominant harmonic - you'll always prefer one phase over other
read about H2 an Korg B1, then read everything else
point is in phase flip of dominant harmonic - you'll always prefer one phase over other
Changing Aleph J clone from irfp 240 to irfp 150
I am gong to put some irfp150 mosfets in my aleph J to try them there....
Standard 22vdc rails, standard power supply. 4U/400mm case.
Just to confirm, I will change the source resistors to 0R27 / 3W, and leave the output resistors as four 0r47/3W in parallel.
If I am wrong on the resistors, please let me know.
Matt
I am gong to put some irfp150 mosfets in my aleph J to try them there....
Standard 22vdc rails, standard power supply. 4U/400mm case.
Just to confirm, I will change the source resistors to 0R27 / 3W, and leave the output resistors as four 0r47/3W in parallel.
If I am wrong on the resistors, please let me know.
Matt