gtfields13
Well-known member
At the beginning of January I finished my first PCB for the AionFX Andromeda Deluxe version of the Nordland ODR-C. Once I dealt with a detached pad (from bending the large Panasonic ECQ substitute for unavailable 2.2µF box film capacitor) it worked fine. Playing around with it, I could understand why this has a good reputation - I felt all the controls were responsive and did something useable and at max drive and distortion it had a nice sustain through fade out.
I finished my second board yesterday with a few componenbt variations and when I hooked it up, it's similar when clean, but at the same max distortion the distorted signal is gated or velcro spitty with a rough drop out that I don't like. At first I thought this was Op Amp related, as I was trying a different Op Amp, but when I swapped in the same batch of RC4558s there is no change.
I am not clear how velcro or gating happens with Op Amps, so I went ahead and measured all lead/pin voltages for the three transistors and both Op Amps. I also measured the input buffer JFET with no signal and a 2V sine wave. I'll be damned if there is any practical difference between the levels at any point, so I don't even have a lead to explore to find out what is controlling the distortion on fade out.
Here are the primary component differences in the builds. There are variations in source (i.e. WIMA vs Kemet film) but no other variations in the component types or values.
I would appreciate any suggestions on what else I could measure or test, or even what I should be considering for swapping into the 2nd build to smooth out the sound. I rather like my first build, and would like to be able to build it reliablty so I can put it in a Phido Sound case for future sale.
Build Instructions
Andromeda Deluxe
Measurements
These align with the troubleshooting values in Aion's kit build troubleshooting, except my JFET source is different, but I am also using a different transistor (5457 instead of J112)
Pictures
(In the 2nd build I bottom-side soldered some of the mid-board potentiometers so they don't look well attached on the top-side. I will touch this up before I put them in a case, but they are firmly connected (i.e. no intermittent behavior when flexed or rotated)
Smooth Build (#1)
Gated Build (#2)
I finished my second board yesterday with a few componenbt variations and when I hooked it up, it's similar when clean, but at the same max distortion the distorted signal is gated or velcro spitty with a rough drop out that I don't like. At first I thought this was Op Amp related, as I was trying a different Op Amp, but when I swapped in the same batch of RC4558s there is no change.
I am not clear how velcro or gating happens with Op Amps, so I went ahead and measured all lead/pin voltages for the three transistors and both Op Amps. I also measured the input buffer JFET with no signal and a 2V sine wave. I'll be damned if there is any practical difference between the levels at any point, so I don't even have a lead to explore to find out what is controlling the distortion on fade out.
Here are the primary component differences in the builds. There are variations in source (i.e. WIMA vs Kemet film) but no other variations in the component types or values.
- Q2/Q3 are BC549C (correctly inverted) on the smooth board (#1) and MMBF5088 on the gated board (#2)
- I used Kemet Film (box film) 1µF on #1 and Hongzhi (dipped) on #2
- I used Panasonic (dipped film) 2.2 µF on #1 and Panasonic (bipolar electric) on #2
I would appreciate any suggestions on what else I could measure or test, or even what I should be considering for swapping into the 2nd build to smooth out the sound. I rather like my first build, and would like to be able to build it reliablty so I can put it in a Phido Sound case for future sale.
Build Instructions
Andromeda Deluxe
Measurements
These align with the troubleshooting values in Aion's kit build troubleshooting, except my JFET source is different, but I am also using a different transistor (5457 instead of J112)
Pictures
(In the 2nd build I bottom-side soldered some of the mid-board potentiometers so they don't look well attached on the top-side. I will touch this up before I put them in a case, but they are firmly connected (i.e. no intermittent behavior when flexed or rotated)
Smooth Build (#1)
Gated Build (#2)
