I'm guessing You won't get any issues with heat, WOW
what a lot of heatsink.If i had a hat, i would tip it for You, great job.
Best regards
Ebbe
Aluminum has a thermal conductivity a few thousand times higher than epoxy, steel about 500 times as much.
Means that the larger part of the energy that heats the disc, goes from the metal side of the power device to the aluminum heatsink, then through the steel bolt to the washer.
The screw/bolt head that holds the power device down is an even less efficient heatsink
think harder
or - don't think about that at all .........
yeah - force spreader it is
metal tab on mosfet is on heatsink side ........ so - conclusion about temp transfer direction is ....... ?
I took your advice, dont think at all.
Drank some beer last night after the Amp gave me problems, and had a 5 STAR lunch and dinner today.
and then I played music from the amp after that
Amp idles between 7-12mv DC offset. The heatsink is warm only. I used variac to run the amp as high as 27V rails, no problem. I am thinking the case is more than enough!
Well, back to the top with a mini thread, seems like a fun build ...
I got a board from chipamp.com, and a snubber PS board, this should let me do double duty with my 3886 experiments.
Any thoughts on using an Avel Y236651 250VA 18V+18V Toroidal Transformer
mentioned in this thread:
Thread Link
As the PS?
Just input the digi key parts list, and had to make a sup for the diodes, but it was direct.
On the downloaded parts list, it says Q1 and Q2 need matched vgs, but it seems more like that should be Q4-Q5 or/and Q6-Q7 from my thread reading, comments.
It also seems like ordering 10 should give me a good chance at matching.
Any thoughts?
I got a board from chipamp.com, and a snubber PS board, this should let me do double duty with my 3886 experiments.
Any thoughts on using an Avel Y236651 250VA 18V+18V Toroidal Transformer
mentioned in this thread:
Thread Link
As the PS?
Just input the digi key parts list, and had to make a sup for the diodes, but it was direct.
On the downloaded parts list, it says Q1 and Q2 need matched vgs, but it seems more like that should be Q4-Q5 or/and Q6-Q7 from my thread reading, comments.
It also seems like ordering 10 should give me a good chance at matching.
Any thoughts?
my 2c of the theoretical, things I've read.. and things I've experieced.
Technically, it could still be mini at 24V, but you'd have to bias the output devices (Q6,7) at lower current... depending of course on your heatsink available. In the grand scheme, this setup is prone to less-than-better overall performance considering that the circuit requires a certain amount of current to insure that the active current source (Q7) is operating properly. Adding to that thought, there is the concept of the ol' sweet spot with these particular devices and their wanting at least a certain amount of current to achieve lower distortion and better sound.
If you essentially want a hotter Mini, then you can do what I did.. 15V ac for 18.5V dc with the output pair biased at 1.5 amps, which equates to about 55 watts of heat to slake off and about 15 watts of output to the speakers. For me this is plenty of amp, but your needs/speakers/room might be different. Something to consider.
Q1 and Q2 ideally should be matched. If not, then you'll certainly want a trimmer pot at R8 to keep the DC offset less than 50mV as a result from mismatching of these pairs. I took a belt and suspenders approach here with the pot and matched pairs from techDIY. Easy to obtain and there's no logical reason not to just buy them matched, unless you want to match them for the diy experience. Q6 and Q7 do not need to be matched, unless you are building a A30 or other multi-pair output amp.
the above references brianGT boards/schematic.
Technically, it could still be mini at 24V, but you'd have to bias the output devices (Q6,7) at lower current... depending of course on your heatsink available. In the grand scheme, this setup is prone to less-than-better overall performance considering that the circuit requires a certain amount of current to insure that the active current source (Q7) is operating properly. Adding to that thought, there is the concept of the ol' sweet spot with these particular devices and their wanting at least a certain amount of current to achieve lower distortion and better sound.
If you essentially want a hotter Mini, then you can do what I did.. 15V ac for 18.5V dc with the output pair biased at 1.5 amps, which equates to about 55 watts of heat to slake off and about 15 watts of output to the speakers. For me this is plenty of amp, but your needs/speakers/room might be different. Something to consider.
Q1 and Q2 ideally should be matched. If not, then you'll certainly want a trimmer pot at R8 to keep the DC offset less than 50mV as a result from mismatching of these pairs. I took a belt and suspenders approach here with the pot and matched pairs from techDIY. Easy to obtain and there's no logical reason not to just buy them matched, unless you want to match them for the diy experience. Q6 and Q7 do not need to be matched, unless you are building a A30 or other multi-pair output amp.
the above references brianGT boards/schematic.
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a few comments ...
Part list from here:
http://chipamp.com/beta2/wp-content/uploads/miniALEPH-parts_list.xls
pulled from the mini tab ...
Happen to have the transformer for my gainClone playing around. Have not really got into that yet, but . The heat sink requirements are reasonable! And it looks fun to play with the point to point. May or may not make it into the house.
Looking at the Mini due to heat sink/case size as need to ensure domestic tranquility, and I don't think that is going to be possible with a Alep 30.
Got my feet wet with a AmpCamp build, and I really like the way it sounds so far, but need the extra 10 watts. Not quite enough oomph ... But the leds fired up on the first go, and the bias set without issue.
Picking up another Torriod is totally within the quesiton, 12-0-12 seems to be the sweet spot for a Mini-A. Is that correct?
Dave
Part list from here:
http://chipamp.com/beta2/wp-content/uploads/miniALEPH-parts_list.xls
pulled from the mini tab ...
Happen to have the transformer for my gainClone playing around. Have not really got into that yet, but . The heat sink requirements are reasonable! And it looks fun to play with the point to point. May or may not make it into the house.
Looking at the Mini due to heat sink/case size as need to ensure domestic tranquility, and I don't think that is going to be possible with a Alep 30.
Got my feet wet with a AmpCamp build, and I really like the way it sounds so far, but need the extra 10 watts. Not quite enough oomph ... But the leds fired up on the first go, and the bias set without issue.
Picking up another Torriod is totally within the quesiton, 12-0-12 seems to be the sweet spot for a Mini-A. Is that correct?
Dave
people historically used 12v because it was a minimum voltage.. and in keeping with the whole 'mini' theme. I assume these people already had some bigger amps. I went 15v as it's my main amp.. wanted a few more watts.
Honestly, the whole form factor of a mini and an A30 aren't that much different. A pair of very prominent sinks lol.. one CD player thickness or two CD player thickness.. take your pick.. and $$.
Honestly, the whole form factor of a mini and an A30 aren't that much different. A pair of very prominent sinks lol.. one CD player thickness or two CD player thickness.. take your pick.. and $$.
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Can Anyone please help with this issue ?
Briangt aleph PCB's & his BOM
http://www.diyaudio.com/forums/pass-labs/231851-mini-aleph-some-output-problem.html
Briangt aleph PCB's & his BOM
http://www.diyaudio.com/forums/pass-labs/231851-mini-aleph-some-output-problem.html
Dear forum ... a while back, I asked a few questions .... since then, did a bunch of reading, and got some heat sinks.
Going to go with an Antek 12V, keeping the 18V in the gain clone, and going to build it out.
See that I only need one set of matched transistors, and the others to not need matched.
Rest of the parts look pretty simple.
So, on to the matched set .... after doing a bunch of reading, seems like a project in itself to build a circuit, and match at home, at the same time, it seems "hard" to find a RELIABLE place to buy a matched set.
Any thoughts?
Dave
Going to go with an Antek 12V, keeping the 18V in the gain clone, and going to build it out.
See that I only need one set of matched transistors, and the others to not need matched.
Rest of the parts look pretty simple.
So, on to the matched set .... after doing a bunch of reading, seems like a project in itself to build a circuit, and match at home, at the same time, it seems "hard" to find a RELIABLE place to buy a matched set.
Any thoughts?
Dave
Matching isn't hard. Your circuit can be build with clip leads and consists of just a power supply and resistor. Just allow the devices to stabilize to minimize temperature effects. I let mine go a minute which seems to be enough.
Of course if you're willing to do a bit of lead bending you can make a mini AJ with matched parts from h_a or the store.
Of course if you're willing to do a bit of lead bending you can make a mini AJ with matched parts from h_a or the store.
Here is my very lame youtube video about matching. I now have a bench power supply to use. This allows better control over voltage and current. But the old battery and resistor worked fine for me.
My Mini A is running higher bias/rails and the DC offset is pretty much zero. I spent a bunch of time matching my IRF9610 mosfets.
https://youtu.be/HAkYXDqOxcA
My Mini A is running higher bias/rails and the DC offset is pretty much zero. I spent a bunch of time matching my IRF9610 mosfets.
https://youtu.be/HAkYXDqOxcA
After seeing the thread come alive again I just pulled my boards out of storage.
I really don't want to use a heavy transformer for another heavy ampto lug around when I move (I move a lot for work) so has anyone successfully implemented a switch mode PS with these boards?
If not I will most likely put them up in the swap forum.
Thank you in advance,
Troy
I really don't want to use a heavy transformer for another heavy ampto lug around when I move (I move a lot for work) so has anyone successfully implemented a switch mode PS with these boards?
If not I will most likely put them up in the swap forum.
Thank you in advance,
Troy