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Stumbling on a forgotten prototype

Every once in a while, I’ll dig through my box of forgotten designs and stumble across one that picks my interest. A lot of times I won’t remember what’s actually in the box or what circuit I designed so it’s almost like a rediscovery of where I was in that moment in time. Now not all designs turn out to be great. Some of them I end up coming back to and re-tweaking to make it useful or further evolve the circuit, but that doesn’t always work out. However, this time turned out to be quite the surprise.  The one Read more

By Steve, ago

Masco WLCW-A Wireless Intercom Conversion – Part 1

While browsing through one of the online marketplaces, I stumbled upon this little gem. The price was right—only $40! I didn’t care if it worked or not, as I had other plans for it. The tube complement consisted of a single 12AX7 and 12AT7. Initially, I thought it could work as a small preamp, but then I realized it had a built-in speaker. That’s when the idea hit me: I could turn it into a mini practice amp with the added bonus of a speaker out to drive any cabinet I wanted. But the real question was, how did I Read more

By Steve, ago

Mystery Shin-Ei FET & Silicon Transistor Amplifier – Part 2

Servicing the Amplifier – Old Capacitors Out, New Capacitors In First thing to do was to replace all the electrolytic capacitors through out the amplifier. There wasn’t any hum or leakage on the originals, but they were well past due to be swapped out. Pulled out the old japanses caps and replacement them with some high quality new production caps. Fired the amplifier back up after servicing and the sound was actually a little more full sounding as well as the tremolo came more alive and smoother sounding. Messing with the reverb After playing around with the amplifier, I rather Read more

By Steve, ago

Mystery Shin-Ei FET & Silicon Transistor Amplifier

Recently I was browsing through Reverb as I do on occasion and stumbled across this little gem. Tried doing a little research on what the amp actually was or who made it, but could find very little detail on it. The price was pretty cheap, amp was in good condition however the seller said there was no output. I decided to make an offer and see what the story was on this little gem. First inspection of the Amplifier The amplifier arrived packed very well and was a lot smaller than I thought it was going to be. Tolex and Read more

By Steve, ago

Bogen Challenger C-100 Conversion – Part 1

This will be the first in a series of amp conversion posts that I am working on over the next few months. I will be showing how I go about planning out what i want to change on the circuit, the overall goal for the amp and the process of converting. First up – Bogen Challenger PA Amplifier I stumbled across this amp while looking through Facebook marketplace in search of transistors and other parts. It happened to be local and the price was right. Most of these solid state amplifiers go for pretty cheap, so I figured what the Read more

By Steve, ago