The hum-breaking resistor will help a lot. It eliminated the hum on my Aleph J.
This choke could work as well, to reduce the hum on DC rails. 159ZJ Hammond Manufacturing | Mouser Australia
If you have an original First Watt F6 in decent condition that you’d like to get rid of Please PM me to see about a sale or trade. I’ll happily get you a nice chassis for your AJ project. Thanks
Hi, guys.
I have some trouble with my Aleph j.
Everything was great one week ago. When i came back from business trip, i switched it up and heard noise in the left channel tweeter.
I have measured bias and offset in both channels. Bias is ok. Right channel offset is constant (2mV). Left channel offset is dancing from -8mV to 6mV and it always changes. I think it is the reason of the noise, but who is guilty for it? Offset variable resistor? When i rotate it, offset changes with jumps, not smooth.
The noise has variable frequency and volume level. Like a wind.
Please give me an advice, how to fix it.
I have some trouble with my Aleph j.
Everything was great one week ago. When i came back from business trip, i switched it up and heard noise in the left channel tweeter.
I have measured bias and offset in both channels. Bias is ok. Right channel offset is constant (2mV). Left channel offset is dancing from -8mV to 6mV and it always changes. I think it is the reason of the noise, but who is guilty for it? Offset variable resistor? When i rotate it, offset changes with jumps, not smooth.
The noise has variable frequency and volume level. Like a wind.
Please give me an advice, how to fix it.
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Unfortunately, I have checked the trimpot and it is ok.
How can i check if it is CCS oscillation?
I see two ways to solve oscillation problem:
1. Replace Q2 from ZTX550 TO BC560CTA
2. Install R6&R30 resistors instead of jumpers.
What are the correct values for R6&R30?
How can i check if it is CCS oscillation?
I see two ways to solve oscillation problem:
1. Replace Q2 from ZTX550 TO BC560CTA
2. Install R6&R30 resistors instead of jumpers.
What are the correct values for R6&R30?
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ref. too sch in post #1
R6 jumper, R8' not fitted, R8 1K, R7 not fitted, R7' 2K trimpot, R27A jumper, R27B not fitted, R27 100K trimpot (preset to half), R30 either jumper or anything of round value up to 1K
R6 jumper, R8' not fitted, R8 1K, R7 not fitted, R7' 2K trimpot, R27A jumper, R27B not fitted, R27 100K trimpot (preset to half), R30 either jumper or anything of round value up to 1K
Voltage drops across R7 and R8 are constant while output DC voltage dances from 0 to 10 mV.
What could have happened to it?
Why can it be so unstable?
Other channel is good, output offset is stable.
What could have happened to it?
Why can it be so unstable?
Other channel is good, output offset is stable.
since you have mosfets on wires, it' easy to unscrew pcb and inspect all solder joints
re-do anything looking suspicious
re-do anything looking suspicious
I have replaced: Q2,Q3,Q3, all trimpots, R30(1kOhm) and nothing helps.
Bias sets correctly, offset is jumping.
Rails 22.7V-0V-23.1V.
Solder is clean, without shorts.
Now i have no idea, how to fix it.
Please, help me!
Bias sets correctly, offset is jumping.
Rails 22.7V-0V-23.1V.
Solder is clean, without shorts.
Now i have no idea, how to fix it.
Please, help me!
I have some Aleph 30 boards that I built many years ago and since removed for another build. I want to build an Aleph again, preferably the Aleph J but the store is out of boards. I distinctly remember somewhere on this forum Nelson telling how to convert the Aleph 30 over to an Aleph J but I have no idea where to find it again. Anyone have a better memory than me?
Is post #9 what you were thinking of?
https://www.diyaudio.com/forums/pass-labs/267857-aleph-design-reloaded.html#post4184920
Also ZM's classic A30 to AJ conversion pdf here:
https://www.diyaudio.com/forums/pass-labs/263951-aleph-30-noise-channel.html#post4121767
https://www.diyaudio.com/forums/pass-labs/267857-aleph-design-reloaded.html#post4184920
Also ZM's classic A30 to AJ conversion pdf here:
https://www.diyaudio.com/forums/pass-labs/263951-aleph-30-noise-channel.html#post4121767
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I believe so, many thanks. I just figured someone has a better memory than me. I built the Aleph 30 many years ago and since then I like to believe that I have better skills now especially matching the output mosfets. I did notice comparing the Aleph 30 vs the Aleph J that the damping factor is much higher with the Aleph 30 than the aleph J. I think that one thing that improves the damping factor is the 6 output devices per channel. Converting my Aleph 30 to the Aleph J may produce the best of both worlds.
Probably a silly question, but: Can I build these as monoblocks and run them balanced? If so, do I expect 50W per channel or more?
I'm fairly new to building electronics (B1 and Whammy so far..)., so please understand that. I also really need amps with balanced inputs, due to the horrible EM/RF/I here.
I'm fairly new to building electronics (B1 and Whammy so far..)., so please understand that. I also really need amps with balanced inputs, due to the horrible EM/RF/I here.