Re the Aleph J kit of parts:
1. the Mosfets, 8 in all, have different numbers on them, no two the same. Significance? Jim noted that they are interchangeable. Just checking.
2. I assume the pots w 104 are for R7 and the pots w202 are for R27A, but what to use for R8?
3. R15 calls for a 1K resistor, but there are 4 of them in the package. Can I assume the "extras" are for R8?
1. the Mosfets, 8 in all, have different numbers on them, no two the same. Significance? Jim noted that they are interchangeable. Just checking.
2. I assume the pots w 104 are for R7 and the pots w202 are for R27A, but what to use for R8?
3. R15 calls for a 1K resistor, but there are 4 of them in the package. Can I assume the "extras" are for R8?
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All good questions!
1) The numbers on the Mosfets are written on the back, and they are just a discrete number that Buzz gave them in order to sort. The Mosfets are a matched octuplet, so just use them in any of the power Mosfet locations.
2) The pots are 2digit + multiplier, so the 202 is 20+00 = 2K, and the 104 is 10+0000 = 100K. Opposite what you thought. The 100K is R27 pot and the 2K is R7 pot.
3) Yes, use a 1K in the R8 position. The pot should only be used if you need to adjust the bias on the input LTP, which will be pretty rare.
Received my Aleph J parts kit yesterday.
Jim, I'm really impressed, the little JFet's are measured:
8.935 mA and 8,950 mA for one channel.
And the other channel are 8.920 mA and 8.935 mA.
That's really good matching! Within 0.015 mA
I guess your little bag with JFets is bigger then you wants us to believe...
Thanks again! Walter
Jim, I'm really impressed, the little JFet's are measured:
8.935 mA and 8,950 mA for one channel.
And the other channel are 8.920 mA and 8.935 mA.
That's really good matching! Within 0.015 mA
I guess your little bag with JFets is bigger then you wants us to believe...
Thanks again! Walter
Any update on the PSU parts kit? I've finished the amp boards and am about ready to order the PSU v3 from DIY store along with a package of Kerathem insulators. I am not pre-ordering the chassis at this time because I'm not sure whether I want a 5U pr 4U. Jim seems to be saying that the 4U is a bare minimum. I'm just not sure how "bare" a minimum that is and how much more beneficial the 5U would be. Cost for 5U is not much more, but I'd rather have something smaller.
Also, if the 5U is the selected, that would provide a bit more room for separate power supplies. I have read that the Aleph J is fine with one power supply. How much of a marginal benefit is there in having two?
Also, if the 5U is the selected, that would provide a bit more room for separate power supplies. I have read that the Aleph J is fine with one power supply. How much of a marginal benefit is there in having two?
PSU update -
I have the parts, but of course made one Snafu and need to determine if the heatsink I ordered will fit perfectly, and if so I will get some TO-220 diodes for it.
Specifically - the heatsink that the PCB was designed around was out of stock, with a 15 week lead time. I ordered one that was similar, thinking it only differed in height.
But that heatsink is also a little narrower, and will not fit a TO-247/TO-3P package. No worries, I will return the diodes and replace them with a (nicer) diode in TO-220. The PCB will take either package, so the only thing that needs verification is the heatsink itself.
I don't currently have a new PSU board, as it's in an order currently in transit, but a neighbor does, I will verify that the heatsink is good for the board and then get the other diodes.
I have all the other parts on hand. (Which is a lot of stuff!)
51frankie - the main benefit of a second supply is having the second transformer and building it completely dual mono. The circuit runs wonderfully on one.
As for chassis, the 4U is fine, it's just going to be hot. But the Alephs have always been heaters, so that's normal. The difference in size (volume) from the 4U to the 5U is significant.
I have the parts, but of course made one Snafu and need to determine if the heatsink I ordered will fit perfectly, and if so I will get some TO-220 diodes for it.
Specifically - the heatsink that the PCB was designed around was out of stock, with a 15 week lead time. I ordered one that was similar, thinking it only differed in height.
But that heatsink is also a little narrower, and will not fit a TO-247/TO-3P package. No worries, I will return the diodes and replace them with a (nicer) diode in TO-220. The PCB will take either package, so the only thing that needs verification is the heatsink itself.
I don't currently have a new PSU board, as it's in an order currently in transit, but a neighbor does, I will verify that the heatsink is good for the board and then get the other diodes.
I have all the other parts on hand. (Which is a lot of stuff!)
51frankie - the main benefit of a second supply is having the second transformer and building it completely dual mono. The circuit runs wonderfully on one.
As for chassis, the 4U is fine, it's just going to be hot. But the Alephs have always been heaters, so that's normal. The difference in size (volume) from the 4U to the 5U is significant.
PSU update -
I have gotten to examine the new PSU board and the heatsinks that I have (all 360 of them) do fit. Nicely, as a mtter of fact...
I need to return the TO-3P diodes and exchange them for a similar diode in the TO-220 package. This process is started and the new diodes will hopefully ship today.
In the meantime I will package up everything else and have it ready to go awaiting the receipt of the new diodes, then it will all ship. I will not do a partial shipment - that would make the total post and carriage costs ridiculous.
Amp Kit update -
At Burning Amp our friend at Pass Labs came through again (Thanks Wayne!!!) and I have another (small) quantity of J108. I have yet to match them, and do not know how many kits I will be able to make from them, but probably no more than 15.
Do not contact me yet. I will go through the list of people on this thread that I had to turn away the first time and contact you, and once I have offered to them in order, I will open it up for the rest.
As last time, the Amp kit of parts will be only one to a customer.
Also it will take a while to get the rest of the parts on hand, so it will be a few weeks at the minimum. Watch this thread for updates.
I have gotten to examine the new PSU board and the heatsinks that I have (all 360 of them) do fit. Nicely, as a mtter of fact...
I need to return the TO-3P diodes and exchange them for a similar diode in the TO-220 package. This process is started and the new diodes will hopefully ship today.
In the meantime I will package up everything else and have it ready to go awaiting the receipt of the new diodes, then it will all ship. I will not do a partial shipment - that would make the total post and carriage costs ridiculous.
Amp Kit update -
At Burning Amp our friend at Pass Labs came through again (Thanks Wayne!!!) and I have another (small) quantity of J108. I have yet to match them, and do not know how many kits I will be able to make from them, but probably no more than 15.
Do not contact me yet. I will go through the list of people on this thread that I had to turn away the first time and contact you, and once I have offered to them in order, I will open it up for the rest.
As last time, the Amp kit of parts will be only one to a customer.
Also it will take a while to get the rest of the parts on hand, so it will be a few weeks at the minimum. Watch this thread for updates.
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