orbilius
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Cool journey - watching!
Been a while since the last update!
First, here is a photo of the superOTL interior now that the choke is mounted:
Over the past few weeks I finally got around to adding in the hi/low gain switch to the superOTL following the GoldPoint schematic in my previous post. Works fantastic and provides a much more usable volume knob range. I attempted to implement global negative feedback, but it appears to work as positive feedback because it amplifies the baseline noise of the amplifier! I'll have to revisit this at some point. I'm pretty much shooting in the dark trying to figure out the R and C values for the negative feedback right now. I need to do some more research and figure out how to dial in these values.
This is the hi/low gain switch. I swear the spaghetti of wires is actually decently organized!
And from the front you can see the feedback resistors and capacitors on the very front nylon standoffs, connected to the outputs of the large Mundorf output capacitors.
In my next post I'll document the lessons I learned from this project, to hopefully spare others from the pitfalls I encountered.
Otherwise, for now I am going to consider the superOTL project done, and move onto the next amplifier project!
----
After recently getting to experience a DNA Stellaris for a few days, I now have a strong desire to build a 2A3 amplifier. I want to use the tube selection as the DNA Stellaris given how much I enjoyed it - 6N1P input tube, 2A3 output tubes, and 5U4G tube rectification (but may do solid state instead TBD). I have never heard the Focal Utopia sound so good until I paired it with the Stellaris. The resolution and clarity, detail, and dynamics were so impressive, I am now chasing that delectable 2A3 sound.
With this idea in mind, I picked up a few items on eBay - from Pete Millet I got a power supply PCB that uses the E-Chokes from Tentlabs, as well as some UX4 socket prototyping PCBs; and from another seller I got DC heater boards. I'm thinking of mounting these to a piece of wood to serve as my prototyping setup for this project.
While I have a decent beginner skills at building an amp at this point, my design skills are lacking, so the goal of this project will be to expand my design skills.
-----
I am also still working on the aforementioned switchbox. This is actually a build for a friend, and he and I settled on these final specs:
I have all the parts on hand and am currently designing the chassis for Landfall to manufacture. I will be using one of their "Simple Single" chassis and have them machine the cutouts for all the XLR and RCA inputs, rotary switches, and volume knobs. Once I have the chassis finalized, I will post some pictures on here, and of course document the actual build process.
First, here is a photo of the superOTL interior now that the choke is mounted:
Over the past few weeks I finally got around to adding in the hi/low gain switch to the superOTL following the GoldPoint schematic in my previous post. Works fantastic and provides a much more usable volume knob range. I attempted to implement global negative feedback, but it appears to work as positive feedback because it amplifies the baseline noise of the amplifier! I'll have to revisit this at some point. I'm pretty much shooting in the dark trying to figure out the R and C values for the negative feedback right now. I need to do some more research and figure out how to dial in these values.
This is the hi/low gain switch. I swear the spaghetti of wires is actually decently organized!
And from the front you can see the feedback resistors and capacitors on the very front nylon standoffs, connected to the outputs of the large Mundorf output capacitors.
In my next post I'll document the lessons I learned from this project, to hopefully spare others from the pitfalls I encountered.
Otherwise, for now I am going to consider the superOTL project done, and move onto the next amplifier project!
----
After recently getting to experience a DNA Stellaris for a few days, I now have a strong desire to build a 2A3 amplifier. I want to use the tube selection as the DNA Stellaris given how much I enjoyed it - 6N1P input tube, 2A3 output tubes, and 5U4G tube rectification (but may do solid state instead TBD). I have never heard the Focal Utopia sound so good until I paired it with the Stellaris. The resolution and clarity, detail, and dynamics were so impressive, I am now chasing that delectable 2A3 sound.
With this idea in mind, I picked up a few items on eBay - from Pete Millet I got a power supply PCB that uses the E-Chokes from Tentlabs, as well as some UX4 socket prototyping PCBs; and from another seller I got DC heater boards. I'm thinking of mounting these to a piece of wood to serve as my prototyping setup for this project.
While I have a decent beginner skills at building an amp at this point, my design skills are lacking, so the goal of this project will be to expand my design skills.
-----
I am also still working on the aforementioned switchbox. This is actually a build for a friend, and he and I settled on these final specs:
- Inputs
- 3 RCA inputs, 1 XLR input
- Outputs
- 1 XLR passthough output from the XLR input
- 3 RCA outputs
- Cinemag transformers for the XLR input for balanced to unbalanced conversion
- An EQ circuit with bass boost
- EIZZ 10k 24-step potentiometer for volume control
- Goldpoint rotary switches for input and output selection
I have all the parts on hand and am currently designing the chassis for Landfall to manufacture. I will be using one of their "Simple Single" chassis and have them machine the cutouts for all the XLR and RCA inputs, rotary switches, and volume knobs. Once I have the chassis finalized, I will post some pictures on here, and of course document the actual build process.
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