zw44 volume too low

Started by sfb, September 03, 2010, 09:09:41 AM

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CynicalMan

Fair enough, but there won't be much of a difference with the buffer or without it.

petemoore

  The buffer circuit has to work when the circuit follows the schematic exactly.
  Each pin has a bias reference, the DMM can find the problem, attach it to the circuit in every way possible [voltage readings are off, something is pulling the emitter way up or theres no ground reference...ie something with the emitter resistor isn't right.
  Stray connect, cold solder, color code misread on the resistor...maybe something else.
  You should get a beep through DMM when it tries the collector to V+ continuity test.
  The base...should have it's resistance value go..where shown and nowhere else.
  Same with the emitter.
  I believe the flat side of the transistor will face 'east' toward the output, pinout being: Emitter/Base/Collector with legs down, print facing you.
Convention creates following, following creates convention.

sfb

It´s alive! Sorry I bothered you guys. It was my bad. One resistor was 1.8k instead of 1.8M. I didn´t have 1.8M so I replaced it with 1M5+270k. I could still use some more output.

petemoore

  All I remember about the circuit was it cut some bass out, can only guess it is supposed to boost pretty good.
  Q1 emitter follower is probably working correctly now though it's output voltage should follow almost exactly it's input voltage 1:1, no boost.
  Then you have your clipping/variable gain stage. The 1meg varies the amount of feedback fed-back from the output [pin 7] to the '-input' pin6. Twisting the knob to loudest should allow pretty strong boost between input to output on this gain stage. The 4u7 and
  Between the opamps is some passive loss [frequency specific voltage reductions].
  The OA2 is assigned as a mild gain stage [10k in feedback loop], mild boost here between input and output.
  If it's supposed to boost more that's one thing, if boost beyond what the schematic would calculate [or the circuit actually is intended to produce] is desired, the .047uf>4k7 string also is part of OA1's gain setting [controls frequency gain when..I'm just trying to make sure it works]..
  I remember it was 'needle-like', and is otherwise quite similar to the tubescreamer [mid-hump-eq-ish] as far as the circuit "map'' [ie different values and a twist here, otherwise feedbackloop/gaincontrolled/clipper/amp circuit w/tone control, just geared for high-trebles w/basscut [which by way of passive losses reduces signal strength.
Convention creates following, following creates convention.

Renegadrian

#24


My VERIFIED layout, I had a wrong res. in the buffer section so it wasn't working at first. Sometimes it happens...Here it goes!
WYLDE!!!
Done an' workin'=Too many to mention - Tube addict!

Renegadrian

The volume I had from the abobe circuit was very very low, lower than the bypassed signal!
I had a JRC4558 in it - swapped for a TL072 and now it screams! 082 works too.
Done an' workin'=Too many to mention - Tube addict!