Hi!
I´m collecting parts for a new Aleph project, so far I´ve got the heatsinks, mosfets and transformers.
The heatsinks (3 pcs 75 x 16 x 6 cm) came from and old EDM and has fins on boths sides, so they need a bit of work before the mosfets can be attached. Lucky me who has a brother that works in a mechanical workshop (the same place as I got them from)
The mosfets are IRFP260N, maybe not the best choice but I bought 50 pcs very cheap on Tradera (swedish "ebay").
Plenty enough to allow tight matching I think. 6 pcs per channel should be enough.
The transformers are ham radio surplus, 2 pcs 2 x 23,5V 300VA toroids. The voltage puts me somewhere between Aleph 3 and Aleph 5, maybe some 40-50W /8 ohms.
The only thing which will cost serious money is PSU caps.
For each channel I´m planning on using 22 000uF - choke - 47 000uF + 10 000uF per rail.
I already have the 10 000uF´s and chokes
(1,1mH 10A iron core, I´ll see if I can decrease the airgap to get a little more inductance since I don´t need 10 A DC capability per channel).
Did someone mention chassis? Well, I hate metalwork so I´ll make it as simple as possible. The heatsinks will be cut in halves and act as sides. Add some L-profiles, aluminium sheets and a wood front and we´re done. At least I hope so!
I will involve my brother as much as possible here, since he has the tools and the skills.
I made him a nice tube guitar amp a while ago so he can´t refuse to help
I´m collecting parts for a new Aleph project, so far I´ve got the heatsinks, mosfets and transformers.
The heatsinks (3 pcs 75 x 16 x 6 cm) came from and old EDM and has fins on boths sides, so they need a bit of work before the mosfets can be attached. Lucky me who has a brother that works in a mechanical workshop (the same place as I got them from)
The mosfets are IRFP260N, maybe not the best choice but I bought 50 pcs very cheap on Tradera (swedish "ebay").
Plenty enough to allow tight matching I think. 6 pcs per channel should be enough.
The transformers are ham radio surplus, 2 pcs 2 x 23,5V 300VA toroids. The voltage puts me somewhere between Aleph 3 and Aleph 5, maybe some 40-50W /8 ohms.
The only thing which will cost serious money is PSU caps.
For each channel I´m planning on using 22 000uF - choke - 47 000uF + 10 000uF per rail.
I already have the 10 000uF´s and chokes
(1,1mH 10A iron core, I´ll see if I can decrease the airgap to get a little more inductance since I don´t need 10 A DC capability per channel).
Did someone mention chassis? Well, I hate metalwork so I´ll make it as simple as possible. The heatsinks will be cut in halves and act as sides. Add some L-profiles, aluminium sheets and a wood front and we´re done. At least I hope so!
I will involve my brother as much as possible here, since he has the tools and the skills.
I made him a nice tube guitar amp a while ago so he can´t refuse to help
...which is a big issue since I want to keep it cheap and new transformers would dig a hole in my budget.
What would be a good transformer for an Aleph X?
I assume my heatsinks can dissipate 150W per channel or so.
Another alternative would be a big CCS loaded source follower fed by a triode VAS. I kinda like the concept, partly because of the lack of global feedback. DC offset would be an issue here, but nothing a servo couldn´t handle I guess.
OTOH, that would be a bit too similiar to one of my current projects, a balanced choke loaded source-follower.
I don´t think I need another one of those
Good choice,
the Aleph5 is much easier to build and stay well in reach of (somewhat) ordinairy size heatsinks. I build my Aleph5 with 2x (30*15*8.4cm) heatsink and they get really hot but not so hot you can cook an egg on them.
Your choke will drop the dc voltage even more and 23.5 is not that much for an Aleph5, I didn't use a choke/fancy rectifier or something else, just 120.000uF per channel an it works just fine.
Good luck building.
the Aleph5 is much easier to build and stay well in reach of (somewhat) ordinairy size heatsinks. I build my Aleph5 with 2x (30*15*8.4cm) heatsink and they get really hot but not so hot you can cook an egg on them.
Your choke will drop the dc voltage even more and 23.5 is not that much for an Aleph5, I didn't use a choke/fancy rectifier or something else, just 120.000uF per channel an it works just fine.
Good luck building.
Fuling said:
you _could_ run it on 2x30V at 2.5A for 150W dissipation but your maximum output power would not be at 8 Ohm.
I'm running my (small) A-X at 2x25V and 2A, it sounds perfect, but I also should get new transformers with lower voltage for more output power (higher current).
On the aleph-x-wiki page there is a link to an excel spreadsheet which does the calculation ("AXE-1"?)
In any case you should use at least 8 transistors per channel.
that said, I don't think you will in any way be disappointed by the A5.
It's easier to build, too...
(I don't really know the A5, I changed my Aleph30 into -X)
But I don't think you couldn't handle the difficulties since I can't really follow your source followers
m.
I haven´t measured the transformers, but they are marked 23,5V. Strange value, but what the heck. Maybe they where custom made for something, I don´t know.
I don´t think the chokes will drop more than a volt or so, they´re wound with about 40-45 turns of 2mm wire so the DC resistance is very low. With 22 000uF directly after the rectifier it won´t be *that* much hum to filter out either. Not exactly a choke input filter, so to speak.
I guess the rails will end up somewhere around +-30V so it will be something in between Aleph 5 and 3.
Aleph or Aleph-X??
Well, I already have a pair of Mini-A monoblocks, built from junkbox parts, so I have an idea how the original Aleph topology sounds and this knowledge does NOT discourage me from building a more serious version!
There are more arguments for building a straight Aleph:
I fully understand the topology (at least I hope so ), and I don´t want to build somethings that I don´t understand.
Haven´t studied the X circuit closely, though.
It requires no fancy protection circuitry, nor any trimming.
(Compared to the hybrid follower I rambled about earlier, I don´t know if this applies to the Aleph-X)
Most important: I can use my stock transformers.
BTW: I have a pair of 2x12V 120VA toroids, maybe they would be more suitable in a (small) Aleph-X?
I don´t think the chokes will drop more than a volt or so, they´re wound with about 40-45 turns of 2mm wire so the DC resistance is very low. With 22 000uF directly after the rectifier it won´t be *that* much hum to filter out either. Not exactly a choke input filter, so to speak.
I guess the rails will end up somewhere around +-30V so it will be something in between Aleph 5 and 3.
Aleph or Aleph-X??
Well, I already have a pair of Mini-A monoblocks, built from junkbox parts, so I have an idea how the original Aleph topology sounds and this knowledge does NOT discourage me from building a more serious version!
There are more arguments for building a straight Aleph:
I fully understand the topology (at least I hope so
), and I don´t want to build somethings that I don´t understand.Haven´t studied the X circuit closely, though.
It requires no fancy protection circuitry, nor any trimming.
(Compared to the hybrid follower I rambled about earlier, I don´t know if this applies to the Aleph-X)
Most important: I can use my stock transformers.
BTW: I have a pair of 2x12V 120VA toroids, maybe they would be more suitable in a (small) Aleph-X?
And... Action!
Today is the big day when my Aleph project got started!
I´ve spent a couple of hours measuring and cutting alu. L-profiles
It´s a dirty job but someone´s got to do it.
Next in line is drilling a bunch of holes in those profiles, marginally less tedious.
I also talked to my brother today about machining the heatsinks, and we agreed to do it next week using a wire EDM to cut them and a CNC mill too remove some of the fins where the mosfets will be attached.
Quite funny to use an EDM to cut the pieces of it´s old neighbour (the heatsinks comes from another EDM that went to kingdom come some months ago)
Today is the big day when my Aleph project got started!
I´ve spent a couple of hours measuring and cutting alu. L-profiles
It´s a dirty job but someone´s got to do it.
Next in line is drilling a bunch of holes in those profiles, marginally less tedious.
I also talked to my brother today about machining the heatsinks, and we agreed to do it next week using a wire EDM to cut them and a CNC mill too remove some of the fins where the mosfets will be attached.
Quite funny to use an EDM to cut the pieces of it´s old neighbour (the heatsinks comes from another EDM that went to kingdom come some months ago)
Good Luck!
btw. trimming the -x is not that difficult, if your parts are not completely out of match.
understanding is not so extremely difficult either (you don't have to reinvent it...)
I was forced to some understanding by the errors I made
as one should use approx. 2 times permanent power, a 120VA transformer may be a little weak for an -x. you can ask the excel sheet about that...
it would be a rather small amp I guess.
m.
p.s. no I'm not trying to talk you into anything
btw. trimming the -x is not that difficult, if your parts are not completely out of match.
understanding is not so extremely difficult either (you don't have to reinvent it...)
I was forced to some understanding by the errors I made
as one should use approx. 2 times permanent power, a 120VA transformer may be a little weak for an -x. you can ask the excel sheet about that...
it would be a rather small amp I guess.
m.
p.s. no I'm not trying to talk you into anything
Talking about piling up parts...
I went to see a couple of DIY-friends yesterday, and amongst other social activitys (like fishing and beerdrinking) we went junkyard shopping. To make a long story short I brought home three HUGE heatsinks which costed me less than four bucks in total. Besides their size they are also shaped in a way that makes it easy to assemble into something box-like.
Since I also have sources for cheap 1x24V 300VA toroids (two per channel) and 66.500uF 40V caps a 15W SoZ might be a future project.
Well, I´ll finish the Alephs first
I went to see a couple of DIY-friends yesterday, and amongst other social activitys (like fishing and beerdrinking) we went junkyard shopping. To make a long story short I brought home three HUGE heatsinks which costed me less than four bucks in total. Besides their size they are also shaped in a way that makes it easy to assemble into something box-like.
Since I also have sources for cheap 1x24V 300VA toroids (two per channel) and 66.500uF 40V caps a 15W SoZ might be a future project.
Well, I´ll finish the Alephs first
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.