Dear team,
I'm building up a Aleph J from the DIYStore and so far it's very clear with all the posts here and easy. I've built (10y ago) a KT88 Class A valve amp as well as Zen Headphone which I still love as well as an Aleph 3 (Aleph J and 3 will share the case and PSU with a switch to allow to choose which amp. I still love my A-3!). I just bought 2x B1 Korg + 1 "Noir" headphones kit I'll need to work after the Aleph J is done... As you can see a lot of good projects in the making! Plus I just found 2 fostex FW305 for a good price so I bought them too (to complement a Backloadedhorn FE206) that I built too. Anyway my skills are good in soldering and pretty ok to understand but sometime I've dumb questions 🙂
Anyway my question is something that has been asked and I didn't find a clear answer. I've bought 25 IRF240 and I'm planning to match them. I've an adjustable PSU (0-30V and 0-10A) and before I start measuring the Vgs I wanted to check if I can use it to match them and what should be the Volts/Amps to test them.
Thanks in advance!
Fred
I'm building up a Aleph J from the DIYStore and so far it's very clear with all the posts here and easy. I've built (10y ago) a KT88 Class A valve amp as well as Zen Headphone which I still love as well as an Aleph 3 (Aleph J and 3 will share the case and PSU with a switch to allow to choose which amp. I still love my A-3!). I just bought 2x B1 Korg + 1 "Noir" headphones kit I'll need to work after the Aleph J is done... As you can see a lot of good projects in the making! Plus I just found 2 fostex FW305 for a good price so I bought them too (to complement a Backloadedhorn FE206) that I built too. Anyway my skills are good in soldering and pretty ok to understand but sometime I've dumb questions 🙂
Anyway my question is something that has been asked and I didn't find a clear answer. I've bought 25 IRF240 and I'm planning to match them. I've an adjustable PSU (0-30V and 0-10A) and before I start measuring the Vgs I wanted to check if I can use it to match them and what should be the Volts/Amps to test them.
Thanks in advance!
Fred
Will you measure on a heat sink or not?
If you’re not using a heat sink keep it to no more than 1 watt.
If you’re not using a heat sink keep it to no more than 1 watt.
Last edited:
Then may as well match close to the operating conditions.
Say 20V Vds and 1A, just be consistent with whatever you decide.
Wait for the heatsinks to hit thermal equilibrium before taking measurements.
Say 20V Vds and 1A, just be consistent with whatever you decide.
Wait for the heatsinks to hit thermal equilibrium before taking measurements.
I copied the current source from the amplifier and mad a test jig that actually tests at the operating condition of the fet. Worked well fo me.
Attachments
Yes The pair of 5w resistors add up to 0.80 ohms. The FETs need not be insulated from the heat sink, just dont let the heatsink touch any touch anything. I let the fet warm up and then measure the Vgs. The exact Vgs is not necessarily important we are just looking for matches.
Hi can someone confirm for me that the present recommendation is for R6 to be a jumper rather than the called out 562R, for the revision C boards as sold by the DIY store presently?
For anyone on a budget who doesn't mind drilling & tapping, there's currently a further 20% discount on these: the largest (and quite possibly smaller versions) has
PASS ALEPH Amp
ClassA
engraved on the front panel.
4315 PASS All aluminum amplifier chassis / Preamplifier case / AMP Enclosure / DIY box (430 *150*300/350/400mm)|Amplifier| - AliExpress
PASS ALEPH Amp
ClassA
engraved on the front panel.
4315 PASS All aluminum amplifier chassis / Preamplifier case / AMP Enclosure / DIY box (430 *150*300/350/400mm)|Amplifier| - AliExpress
With shipping it is almost the advertised price x 3. + add customs/VAT. (But what I like is the screws on the cover plate. It is flat with the cover. That's better than hifi2000)
Aleph J is alive! Below are a few pictures of J up and running in my system.
I read through this entire thread three times between when I decided to take on this project and when I completed it yesterday. I had relatively few questions, but that is only because of the effort and contributions from everyone on the thread previously, so thank you.
I did have an issue setting the offset on the left channel on my initial startup and test. The pot I had used was bad, I could hear the pot click as I turned it, despite the fact I tested the pot and set the pot during assembly. Luckily I had a couple extras and was able to pull the board off and replace that pot.
I had a minor issue with hum when I first connected the amplifier to my system running to my Klipsch RP-600Ms. Standing the Antek on end, rearranging the mains/secondary wiring, and making sure to push the input runs up against the sides of the chassis made all the difference and I now how a completely black background thru the RP-600Ms.
This was my first DIY audio project, and the first time I have soldered anything since I was a kid helping my dad. It seems daunting at the start, but a methodical approach of testing, building, testing and testing some more along the course of the entire build I certainly think made things much easier.
Couldnt be happier!
I read through this entire thread three times between when I decided to take on this project and when I completed it yesterday. I had relatively few questions, but that is only because of the effort and contributions from everyone on the thread previously, so thank you.
I did have an issue setting the offset on the left channel on my initial startup and test. The pot I had used was bad, I could hear the pot click as I turned it, despite the fact I tested the pot and set the pot during assembly. Luckily I had a couple extras and was able to pull the board off and replace that pot.
I had a minor issue with hum when I first connected the amplifier to my system running to my Klipsch RP-600Ms. Standing the Antek on end, rearranging the mains/secondary wiring, and making sure to push the input runs up against the sides of the chassis made all the difference and I now how a completely black background thru the RP-600Ms.
This was my first DIY audio project, and the first time I have soldered anything since I was a kid helping my dad. It seems daunting at the start, but a methodical approach of testing, building, testing and testing some more along the course of the entire build I certainly think made things much easier.
Couldnt be happier!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
markf31,
Nice build. Please use a metal L-angle mounting bracket to properly mount your power transformer. It looks like you have a lot of electrical tape holding it to the chassis. With heat and time, that tape adhesive may give way.
L-Bracket – Toroid
Nice build. Please use a metal L-angle mounting bracket to properly mount your power transformer. It looks like you have a lot of electrical tape holding it to the chassis. With heat and time, that tape adhesive may give way.
L-Bracket – Toroid