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)?