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Don Voth has been servicing electronics for musicians, professional audio engineers and lighting technicians since 1989. Don started his own business in 2001: the Don Voth Electronics Company. Technology has evolved over the past 25 years, but Don Voth is still coming up with dynamic solutions; finding and fixing the most difficult and bizarre technical defects.

Supro Thunderbolt — August 8, 2017

This is a vintage Supro Thunderbolt. Owned by Arthur Bouther. He wanted more gain from this unit. There are 2 ways to do that.
1) Add Decoupling caps across the Cathode resistors of the preamp tubes, or...
2) Add another stage of tube amplification.
This unit already had all the cathode resistors decoupled. So the easy way out is out. But it turned out that one of the tube circuits in the first preamp tube was not being use for anything. So I designed a circuit with that tube element and tapped in after the wiper of the volume control Tested the amp with a dummy load and it makes beautiful symmetric round distortion when you drive the shit out of it. An all around big win!

The last picture shows the mod installed:

Don Fixes Ampeg V4B — September 22, 2017

In this video, Don Voth fixes an Ampeg V4B.

Noisy Vox — September 4, 2017

Watch Don Voth repair a noisy Vox amplifier!

Holy Grail — August 8, 2017

This is a Holy Grail. Most players say it's a good reverb box. This unit makes a whiny hum. My guess is that all Holy Grails do that.

Except, of course, this one. Why is this one different? An original Holy Grail comes with all metal input/output jacks. As you can see, I have replaced those jacks with plastic Neutrik jacks.

Why would I do that?

Metal jacks make a ground connection to the chassis. Hence, we have 3 ground connections to the chassis: the input jack, the output jack and the power jack. This creates "ground loops." By using plastic jacks, I eliminated the ground loops. After that, I had to add a ground jumper from the output jack to the chassis ground. But not all ground points are the same! Grounding at the output jack nut or the AC ground created noise. So I added the green wire and grounded at the voltage regulator on the PCB, as you can see in the picture below:

Fantastic! Now this piece of Holy Sh** has stopped whining and sounds Wholly Great!

Swefog Ultimate 3000 DMX — June 29, 2017

Some of you have heard my motto: " I will fix anything except nuclear weapons and I will try that if you give me a schematic." This is a portable nuclear reactor!

...Well, actually, I am dreaming. It's just a fog machine. But what a fog machine it is! This unit is made in Sweden and top quality is oozing out of it. It does not use heat to make fog; it uses compressed air. Aaron Argo from Springs Church Winnipeg brought this to me. I need to get a relay for it, then it will live again. It is so nice working on such high-grade gear.