Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jalmeida on October 01, 2023, 08:37:50 am
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Hello all,
So not too long ago a fellow amp enthusiast friend gifted me an AC30/4 repro chassis after seeing my AC15 twin build. The AC30/4 has always been a bucket list amp. Something about the chime and grunt of a cranked EF86 amp is just magic. And I thought that the AC30 super twin heads have always been cool. Especially the early fawn variants. And even though the AC30/4 has never been know to come originally in super tein heas format, I had to build a AC30/4 supertwin head. Plus the head isolation from speakers hopefully helps mitigate any of rumored microphonic issues the AC30/4 apparently suffered worse than the AC15.
So I chipped away bit by bit trying to stay as close to JMI as I could tolerate and here it is.
The Vib/Trem switch was replaced with a 1M pot and 560k resistor. Initially I had a 220K resistor, but the speed range was too fast. The 560K seems just right. I also had some issues with the Vib/Trem not working due to some errors on my layout drawing that I since corrected.
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A few more
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Beautiful job!
Those are so foreign to my Fender-oriented brain, it hurts my head to look at it. I don't even know where I would start.
Enjoy it!
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Beautiful job!
Those are so foreign to my Fender-oriented brain, it hurts my head to look at it. I don't even know where I would start.
Enjoy it!
The Vib/trem adds alot of components. The easier part of this build is following the original Vox(worts and all) layout. Not quite kit build easy. But to take the entire circuit and create a modernized layout could make for some improvements and add alot more complexity than what I did.
However, no need because there is already a 30w in circuit form available from hoffman. So could save alot of headache if you decide to build one.