Author Topic: who use EA Tremolo  (Read 2532 times)

good mourning

who use EA Tremolo
« on: November 13, 2004, 11:23:28 AM »
i've finally finished my EA Tremolo unit...
it's good as preamp... but where is the effect?
the tremolo-vibrato in my unit is scarcely audible...
i can't say there's no changing in sound,
but i used other tremolos and the effect was audible!
is it problem of mine, or is this the effect?
i tried with an overdrive, but i can't hear difference in speed and depth too.
i used the same components as in

http://www.generalguitargadgets.com/diagrams/eatrem2_lo.gif

http://www.generalguitargadgets.com/diagrams/eatrem2_sc.gif

with these difference:

Q2, Q4: BF244 / Q3: BC549 / C8: 0.047uF / R12: 22k log pot
R14: 47k B pot


can anyone help me, please?
i know a lot of you uses this stompbox...
good mourning

gez

who use EA Tremolo
« Reply #1 on: November 13, 2004, 12:07:42 PM »
Reduce the value of R7, the 560k resistor.  Tweak as necessary...

Edit:  I'm assuming that you have some tremolo sound coming out of the effect, if not then it's probably the LFO not working (millions of posts in the archives about how to fix this).
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

good mourning

who use EA Tremolo
« Reply #2 on: November 13, 2004, 12:47:08 PM »
Quote from: gez
Reduce the value of R7, the 560k resistor.  Tweak as necessary...

Edit:  I'm assuming that you have some tremolo sound coming out of the effect, if not then it's probably the LFO not working (millions of posts in the archives about how to fix this).


the volume pot works.
what kind of mistake is possible in LFO?
i didn't find a post that really explain where the problem is
it caused by transistors type?
good mourning

good mourning

who use EA Tremolo
« Reply #3 on: November 13, 2004, 12:53:31 PM »
in this page of the forum
http://diystompboxes.com/sboxforum/viewtopic.php?t=26694&highlight=lfo

bluesdevil says that LED doesn't work
you said that LFO doesn't work...
my LED works.
do i have to control the transistor voltage?
good mourning

gez

who use EA Tremolo
« Reply #4 on: November 13, 2004, 02:14:44 PM »
Quote from: good mourning
my LED works.


I can't see a LED in the schematic you linked to but if you've done something alone the lines of the blinking LED mod as shown in the runoff version of the EA then your LFO is working.  Is this what you meant when you said your LED works, ie it pulses in time to the tremolo effect?

If you're hearing some tremolo but it's weak then follow my initial advice "Reduce the value of R7, the 560k resistor. Tweak as necessary..."  If your circuit is just acting as a booster and no tremolo effect can be heard then check the pinout of the JFET, Q2.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

gez

who use EA Tremolo
« Reply #5 on: November 13, 2004, 02:19:35 PM »
OK, I see the LED you're talking about now.  No, it's nothing to do with the LFO.

Your post is vague.  Are you hearing some tremolo effect, or not?  If you can answer this then it'll be easier to diagnose your problem.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

good mourning

who use EA Tremolo
« Reply #6 on: November 14, 2004, 06:01:31 AM »
sorry gez if i was vague
but i can't explain it!
i'll try it:

- the volume works
- the LED of the effect 'on' works
- i'm not interested in LED that pulses as the effect
  R8 is 15k, not 10k-LED
- the depth pot causes no change
- the speed pot causes a bit (a very bit audible!) vibrato (audible when it's max)
- obviously no 'auto volume change' (i.e. the 'tremolo' effect)
- i tried replacing the 560k (R7) down till a 100k res. with no result
- i tried every position of Q2 (turning, changing pins)
- if Q2 is not on the board i can't hear a good sound from my guitar
  (the volume still works but the sound is very bad)
- i don't think it's problem of the depth pot even though is a 1M-A
- transistor Q1 is 2N3904
- FET Q2-Q4 is BF244
- transistor Q3 is BC549, this is positioned as in the ggg layout
- i don't know what to do
- i must give up
- i know someone can help me
- there are a lot of other things to do better than electronics (eating,
  drinking, playing, etc...) above all if i don't understand anything in this
  subject!
-  :wink:


 :?  :(  :cry:
good mourning

gez

who use EA Tremolo
« Reply #7 on: November 14, 2004, 07:32:00 AM »
Quote from: good mourning
the speed pot causes a bit (a very bit audible!) vibrato (audible when it's max)
- obviously no 'auto volume change' (i.e. the 'tremolo' effect)


What do you mean by this?  You say you're not hearing any tremolo then you say you can hear 'vibrato' with the speed pot at max  :?:

When you have the speed pot at max are you hearing some fluctuation in volume, i.e. very slight tremolo effect?  If so then the LFO is working so that isn't the problem.  If this is the case then the thing to concentrate on is Q2.    

Could you post emitter base and collector voltages for Q1 and Q3, and source gate and drain voltages for Q2 please.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

jrc4558

who use EA Tremolo
« Reply #8 on: November 14, 2004, 12:18:14 PM »
I think it's Q2. Check the pinout. Also the polarised capacitor.