Kay tremolo is fuzzy

[Seven64]

so i just finished this vero of the Kay tremolo:

http://www.diystompboxes.com/smfforum/index.php?topic=30976.0

i get the effect, and the tremolo changes with the pot, the only problem is it is SUPER overdriven, and only works on the neck pickups of my guitar.  it works on all the pickup settings but single bridge. 

is it a burnt up transistor? i used the 2n5089's.  also, where it has a 43k resistor i have 2 22k's in series to make a 44k, but i wouldnt think that would matter much.

[Seven64]

just googled it again and found this:

http://aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=11002&g2_serialNumber=2

which has an additional jumper between a 100k resistor and a .22 cap.  think that matters at all?

[Seven64]

installed the jumper, made it smoother but still has that problem.  it also has almost no sustain.

[newfish]

Hi,

I'm sure you'll see lots of suggestions to read the 'Debugging' thread - it's extremely useful.

That being said, my first place to look would be the biasing of your input transistor.  Checking the values of the resistors 'feeding' this component (470K / 43K resistors) won't hurt...

How well-soldered are the two 22K resistors you used?  Might be worth checking that joint.

Checking the value of *all* components is recommended - this isn't meant as a 'smart-ass' comment - it happens to everyone sooner or later...

Hope this gets you started.

Cheers!

[LucifersTrip]

I searched around for other comments on that and it seemed like a common problem with many other DIYs builds was distortion...and the most common answer was that the transistor gains us builders used were too high...

Someone noted that the 2SC828 crossed to something with high hfe (>400), but the actual measurements in his were 100-200.
According to a datasheet I checked, the 2SC828 ranges from 65-700. I have no idea what range the "R" version is.

http://www.diystompboxes.com/smfforum/index.php?action=printpage;topic=16759.0

I also wound up with some distortion. Unfortunately, the 2N3391's I used were higher than 100-200 and I didn't want to de-solder the
transistors.  If I build it again, I'll try lower gains...

You used transistors with even higher hfe's

[Seven64]

yea, i was kinda thinking that.  even tho the vero sheet says to use high gain transistors.  can i use any transistor with the same pinout, or does it need to be more specific than that.  im gonna try for some lower gain stuff here soon, and prolly just socket it.

[LucifersTrip]

yea, i was kinda thinking that.  even tho the vero sheet says to use high gain transistors.  can i use any transistor with the same pinout, or does it need to be more specific than that.  im gonna try for some lower gain stuff here soon, and prolly just socket it.

"any" is too broad...so no, you prob couldn't use a transistor with a gain of 5...you should be able to get sound with any npn silicon with reasonable gain. start with 100 hfe and let your own ears do the choosing

let us know if there's less distortion after you experiment a little.

[PRR]

> it is SUPER overdriven

That plan will not gracefully tolerate different transistors or battery voltages.

Yes, Voltages as requested in the "Debugging" post would be useful.

That layout DOES say "any" and (on the later plan) "experiment".

Let's instead fix the bias to be semi self correcting.

Move one end of the 470K. Change a 43K to 100K (or even open).

[Seven64]

sorry to revive this from the dead, but i have not had any time since i started this semester to mess with any of my stuff till now.  i did the above mod, but now for some reason i am getting no sound at all with the pedal engaged.  ill check it out more tomorrow, as it could be a transistor i didn't get in all the way.  i removed all the previous transistors and installed sockets, so hopefully i will get this thing working before long.

[Seven64]

ok, reviving again.  checked all my solder joints, cleaned a few up, shortened some wires, and switched trannys to 2n5087's.  still not getting any signal thru the effect.  i busted out my audio probe, and i get signal until it hits the 33k input resistor.  it doesnt pass thru the resistor to the copper side of the board tho.  bad resistor?  something else?

also, voltages.  1-4 left to right, a-c top to bottom

source: 9.71v

1
a: 6.21
b: 5.50
c: 0

2
a: 0
b: 6.48
c: 0

3
a: 0
b: 6.51
c: 0

4
a: 7.19
b: 6.55
c: 0

edit:  getting a weak clean signal when effect is engaged tho.  no sound of tremolo or distored tremolo tho.

[PRR]

> it doesnt pass thru the resistor to the copper side of the board tho.

I would put the bright light there.

[Seven64]

does it matter that on my multi meter the resistor in question still holds its normal value?  i measured it after i took it off the pcb.  either way it is still passing just very slight sound when engaged.  the signal goes thru it now and makes it to the first transistor.  i am not sure where to test it from here.  should i try cutting that jumper i made?  switching back the suggestions from about about switching to a 100k?  try a jumper?

[Seven64]

switched it back to the original setup looking for the distorted trem again, and its not passing sound again.  i have rechecked all my solder joints and component values.