I won’t be able to get to it till next week, but will double check that as soon as I can (although it worked before with same source and cable). Thanks for helping me with this.
I have a question about the output voltage. What will be the normal output voltage if i feed it with 0.5V input? My simulations shows +-4.4V, but osciloscope measures only +-2.5V without volume pot and load
^ If built to spec (I'm not sure what you're simulating), you should have 20dB gain => 10X => 5V. Your simulation is closer.
If the load is only the scope, that's a very high impedance. I am not sure what affect that may have. I'd assume you'd still get a proper output voltage, but put in your load and see.
BTW - Always use units, please. I am assuming you mean that your input was 0.5Vp and your output was 2.5Vp => 5X. If your input was 0.5Vrms, that changes things, but you're still off, just a bit further off.
Were you using a differential input? Did you short In- to GND? You typically get 0dB gain (or even slightly negative gain) without that jumper when using a SE input.
If the load is only the scope, that's a very high impedance. I am not sure what affect that may have. I'd assume you'd still get a proper output voltage, but put in your load and see.
BTW - Always use units, please. I am assuming you mean that your input was 0.5Vp and your output was 2.5Vp => 5X. If your input was 0.5Vrms, that changes things, but you're still off, just a bit further off.
Were you using a differential input? Did you short In- to GND? You typically get 0dB gain (or even slightly negative gain) without that jumper when using a SE input.
Thank you very much for the explonation. I've figured out that my signal source was producing full wave, but i considered it as a half-amplitude wave. Now the simulation results perfectly match the real ones
if you're using same Drek to measure both input and output, no need even to think about units, if goal is to get ratio/gain measured
though, when writing about test, good to at least say what's used for measurement, and stay aware of actual units (rms, p, pp)
though, when writing about test, good to at least say what's used for measurement, and stay aware of actual units (rms, p, pp)
Okay, I am back in town and tried out the cord with a different amplifier. No hum, clear, detailed, my iPhone sounds pretty good on my Martin Logan speakers. Back to the amp, is there something else I should try? I thought that a faulty JFET seemed like a likely culprit. Before I goofed up by turning the bias pot when I thought I was setting dc offset (thereby cranking the bias up to heaven knows what), there was no hum and it sounded great.
it's really that simple as pulling out all semis from pcb, and either trying them (easiest in small chinese testitall gizmo) or simply replacing
proper troubleshooting based on measurements in cold and live usually demands some mileage, and when one lacks that (or schematic, so no big picture), you measure for shorts, and then rest is exactly as I wrote - pull out, test, put back same or replacement part
proper troubleshooting based on measurements in cold and live usually demands some mileage, and when one lacks that (or schematic, so no big picture), you measure for shorts, and then rest is exactly as I wrote - pull out, test, put back same or replacement part
Thank you, Zen Mod. With respect to the jfets, I have a matched quadruple. If I use the other matched pair, will that pose a problem when I build the other channel (i.e., is having a matched pair in each channel good enough or do I need 4 matched devices)?
Thanks, it just occurred to me, should I desoldar the mosfets and leave them on the heatsink or remove them from the heatsink before removing the board?
Hey All, Day 1 complete of the build. I got all the boards put together, the case assembled and laid out, and will start wiring things together tomorrow. This was my first time doing a project like this. I really enjoyed it. A digitally controlled soldering iron with a variety of tips really made a difference compared to my DIY cable soldering with a basic iron. Also this website was invaluable. https://diyalephj.blogspot.com/
Before I start the wiring does anyone see any issues with my layout of the power supply parts, or any suggestions on how I could make it better?
Also the 400va 18v Antek transformer only came with 1 rubber piece, does that go on the bottom or top? or do I need to find a 2nd one?
Before I start the wiring does anyone see any issues with my layout of the power supply parts, or any suggestions on how I could make it better?
Also the 400va 18v Antek transformer only came with 1 rubber piece, does that go on the bottom or top? or do I need to find a 2nd one?
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The toroids should come with 2 metal plates and 2 round rubber insulators to prevent damage to secondary windings when mounted.
I have already posted on many occasions an Aleph J layout that minimises both the mains wiring length and the DC wiring length. Please use the advanced search feature in this thread to find posts with my username. You'll see some other pointers I posted to improve the sound. However, get the basic build going okay first, ensure it's all good, and then consider suggested modifications.
People who hear this amp go absolutely ballistic about its sound.... and I'm talking serious high-enders who I've known for a long time.
Good luck.
I have already posted on many occasions an Aleph J layout that minimises both the mains wiring length and the DC wiring length. Please use the advanced search feature in this thread to find posts with my username. You'll see some other pointers I posted to improve the sound. However, get the basic build going okay first, ensure it's all good, and then consider suggested modifications.
People who hear this amp go absolutely ballistic about its sound.... and I'm talking serious high-enders who I've known for a long time.
Good luck.