- Aug 8, 2005
- Reaction score
I think Im going to try dual ganged 25k pots in my poorman 670. It looks like the taper will be o.k when each pot is in parallel with a 40k resistor. Ill let you know how it goes
Thanks god that somebody experienced that problem. I still don't have my unit finished but it was obvious that "VU" must be some low internal meter (ma meter or ua meter). BTW, I don't think that scoping the waveform is necessarily for checking unit. Just proper supply voltage after meter. I presume that you had a huge voltage drop with few kohm meter so tubes were working with low voltage . Bluebird, can U tell us about your voltage after meter? It will be great to know is somebody experienced same problem as you.I found out I had a meter with a high internal resistance so I ended up replacing R6 (22K) with 100 ohms. If your not using the recommended meter I suggest you check your output on a scope to make sure your not starving your 6BC8 plates.
Hey, that's great pimp! Do you have a time to draw a final combination (values) of your time constants?I still felt like the attack knob wasn't changing the time constant enough.
I glanced over the original 670 schematic and realized it has a resistor in PARALLEL with the time constant caps not in series that changes.
Hmm, why Analag went with 10k and 10uF? I wonder
If I understand correctly PM meter works like a DC ma meter since it's connected in series with DC supply. There is no AC voltage. Just DC voltage drop around meter resistance. I think that resistance have to be few Kohms but less can work even better since current is not static because of constant gain change of Valves. I asked few times for DC currents through meter but nobody gave me an answer .I tried removing the resistor inside & put the diodes on them JUST to see how they'd respond as "AC" VU's & the needle hardly moved at all
I think that it should work, I don't see any reason for not... just, c3 have to be changed to 2uF....R18 is not important , I think.. :BUT if we're trying to copy a Fairchild... why not go all the way & use the original time constants & values?
The question is... will it work correctly on the PM version?
PM meter works like a DC ma meter since it's connected in series with DC supply. There is no AC voltage.
"JUST to see how they'd respond as "AC" VU's"