EA Trem Trimpot Troubles

[Alex C]

Hi, I've searched the forum for references to a similar problem, but couldn't find any.  

I used the Runoffgroove schematic for this.  My LED lights and pulses according to the settings, and the rate, volume, and depth controls work as they should.  However, when adjusting the trimpot (100k) I can get either a clean, uneffected sound (just boosted), or distorted tremolo (has the tremolo pulsing sound, but has the "mis-biased" sound too, like a sputtering fuzz).  There is very little "adjustment distance" between the two (meaning that a very slight turn of the pot will change it from one to the other, and I can't get an acceptable mix of the two).  
I checked the orientation of the transistors, and all are correct, as are the electrolytics.  
Should I try a smaller trimpot for more precise adjustment?  Or is something else my problem?  I used a 2N5089 instead of the specified 5088, because that's all I had on hand, and I believe I read that the two are basically identical, but the 5089 has lower noise, etc.   I am most likely wrong, but it seems to be peforming a non-audio job, just manipulating the depth/rate (I forget which).   The other values are as specified, except for the trimpot, for which I substituted a regular pot which happens to be audio taper.  Could this be contributing to my difficulty in locating the proper setting?  

Any ideas?  Thanks.

Alex

[B Tremblay]

The audio taper may be causing difficulty when trying to dial in the correct drain voltage.  Do you have a multimeter or are you tuning by ear?

A linear taper 100k trim (or pot, but you really don't want it to be external) may do the trick.

The 2N5089 shouldn't be a problem, the extra gain won't affect its function as the LFO.

[Alex C]

I have a multimeter, but I tuned by ear.  I didn't see any values listed on the schematic or in the article (but I might not have looked very hard).

I believe I have a 100k linear regular pot, I'll try that and let you know what happens.  Thanks.

[B Tremblay]

I have a multimeter, but I tuned by ear.  I didn't see any values listed on the schematic or in the article (but I might not have looked very hard).

The drain of the MOSFET should be at 4.5 to 5v.

[Alex C]

Hey, I found a 100k trimpot that I had, so I wired it up, and used my DMM to set the drain to 4.7 and around there, but no sound came out.  I had to tune it by ear again, and the sound is not as is should be.   I'm still having the same problem(s) I mentioned before.

Any more ideas or suggestions?   Thanks for your help so far.

Alex

[B Tremblay]

Triple-check the MOSFET and JFET pinouts.

[Alex C]

Hey, I got it working, sounds great!  Thanks very much for your help.

[B Tremblay]

That's terrific!  Thanks for the update, I'm glad you've got it working.

What was the problem?