Warbler and Revibe Builds

[Stymie]

This my first post on the Forum.  My post is a brief description of my Warbler and Revibe builds.  I have a couple questions below concerning my Warbler.

Warbler

I came across Mr. Sluckeys' web site showing his Warbler and Revibe units during my research of the Fender 6G15 unit.  I found these two effects very interesting and decided to build one of each.

My first one was the Warbler.  I had a few questions about the circuit and asked Mr. Sluckey.  He provided answers to all my questions.  I purchased all new components, except an AO-47 I found on eBay, and sheet aluminum to build my chassis.  I completed the build with the following physical location changes:
1.   Moved the On/Off switch to the front panel,
2.   Used a red LED instead of a yellow one,
3.   Reduced the turret board length eliminating the area used in the Revision 1 Warbler.
I also wired the primary circuit from the main to the switch, then fuse, then transformer ala Uncle Doug’s method.

After I completed the build, I tested it and everything works.  I have one issue with thumping with the vibrato engaged.  I can eliminate the thumping by reducing the depth pot to about 2 o’clock.  Can anyone provide any suggestions on how to eliminate the thumping totally?
I also have a question about the balance and mix pots.  I do not completely understand the “proper” setting of the balance pot.  I do not have an O scope and set it by ear.

When the mix pot is at 50%, the volume is much lower than when at either extreme.  Is this as it should be?

The first picture is my Warbler.

Revibe

My second build was the Revibe.  I bought all new parts for this build and assembled it as shown on Mr. Suckeys’ layout diagram with the exception of moving the On/Off switch, lamp, and FS jacks to the front panel.  I also wired the primary circuit from the main to the switch, then fuse, then transformer.

I made the chassis like the one for the Warbler.

I made a bracket that I can lift to compress the reverb springs during transport.  The red knobs are for securing the bracket in the open or compressed position.

There were absolutely no issues with either effect upon testing, NO thumping here.

I have played through both effects coupled and the combination of both vibratos together produces some interesting sounds.

The second picture is my Revibe.

[sluckey]

After I completed the build, I tested it and everything works.  I have one issue with thumping with the vibrato engaged.  I can eliminate the thumping by reducing the depth pot to about 2 o’clock.  Can anyone provide any suggestions on how to eliminate the thumping totally?

At one time there was a 180K resistor across the footswitch jack. The purpose of this resistor was to reduce the level of the LFO signal which will eliminate the "thumping". So, put a resistor back on the FS jack. I suggest using gator clip leads to temporarily clip a resistor across the FS jack. Start with a 180K. If this reduces the warbler effect too much, clip in a larger resistor. Experiment with different resistor values, even up to about 2.2M. Larger values will have a stronger warbler effect but may also begin thumping. When you find a resistor value that gives adequate warbler effect with no thumping, solder it permanently across the footswitch.

I also have a question about the balance and mix pots.  I do not completely understand the “proper” setting of the balance pot.  I do not have an O scope and set it by ear.

Using you ear, turn the mix pot all the way up and note the loudness of the guitar signal. Now turn the mix pot all the way down and adjust the balance pot to match the loudness of the guitar signal. Repeat until you are satisfied that the wet signal and the dry signal are equal loudness.

When the mix pot is at 50%, the volume is much lower than when at either extreme.  Is this as it should be?

Yes but that was an unwanted side effect of using the mixer pot. The reason is the dry signal at the left side of the mix pot (refer to layout) is out of phase with the wet signal at the right side of the pot and the two signals tend to partially cancel each other. You can easily eliminate this behavior by disconnecting the wire from the wiper of the balance pot, and then grounding the left side of the mix pot. Now the pot will operate as a simple output level pot. If you like it better this way, you can totally remove the balance pot and replace with a 47K resistor. There's already a place on the board for the 47K resistor. Also remove the onboard .047µF that connects the BAL pot to the MIX pot. I'll attach a pic to make this clear.

[Stymie]

 
Mr. Sluckey,

Thank you so much for your response.

I will implement the FS resistor tomorrow and adjust my mix pot as you have described.

I will probably leave the mix pot as built, I just wanted to make sure I had not wired something incorrectly there.

I do really like both the Warbler and Revibe.

I will be making two additional post in the coming days about two different tremolos I have built that I am having a bit of trouble with.