I had started a thread a while back (cant seem to find it again)… where I was questioning the values I had used in my audio/amp output (filters) …etc…
It was suggested, that I use LTSpice (which I had never used before)
I downloaded… loaded the sample file given to me by a member here. (Wawa? or Pito? perhaps… I cant recall unfortunately)
Basic (original) summary was:
I have two (SMD) boards…
1 x had headers soldered onto it… and is in a breadboard so I can test things and easily prototype.
I have certain resistor/caps there were NOT populated on the board… but instead had female leads soldered to the board, so I can easily swap out values…etc
1 x is the same board above… but NOT in a breadboard… same resistor/caps not populated and same female leads soldered, so I can quickly change values to match what I test with in the breadboard scenario above.
(with me so far?)
here so pics for visuals… (please lets leave breadboard capacitance/resistance out of this dicussions, form what I recall in this application it doesnt matter/apply)
The breadboard version ‘sounded’ good… but the standalone one didnt match the same audio quality… so it started me to make my initial post months and months ago… (hence the suggestion to use LTSpice to emulate things)
- I sorta chalked things up to: I had fat-fingered a cap value on the standalone board (hence why it didnt sound the same as the ‘breadboarded’ version…
I plan on making the change to the breadboard version… (to whatever LTSpice shows me the way is!)… and then I’ll assemble another ‘stand alone’ board and see if it mirrors the range/volume of the bread-boarded one.
Here is the schematic portion I Had question of values on: (right click >> view image to see large size)
I believe the R5 (8k) & R6 (2k) values are ok…
and the focus was on R8, C18 & C21 mostly… (more so the caps)…
I had been ‘randomly’ changing values and deciding by ear if it was ok or not… but I know this is ‘factual’
Here is the LTSpice example I was given… (attached)
Having very little to no experience with LTSpice… I can change values… but am not clear on what my GOAL is to be (visually) when looking at LTSpice results/output.??
Am I looking for all lines to be ‘together’? all lines to be at top? bottom? (I just dont have any direction here with this app)
I hoping to finally stumble upon a value set that I am CONFIDENT sounds really good (for what I have)… (I assemble these boards myself… and want to try outsourcing, but need to be confident in my final values for the schematic…etc)
Anyways… to re-cap those 3 (5) values are the ones I had/have questions on… and am looking for how to ensure whatever combination I use gives the best results.
thanks for any suggestions/directions…
XL97.zip (467 Bytes)