Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Sonny ReVerb on June 01, 2018, 08:03:20 pm
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I believe Fender used a reverb tank with an insulated input jack and grounded output jack. Using vintage style externally shielded cables and non-insulated chassis jacks, the tank would be grounded and there should be no ground loop.
My last amp (and next amp) has the Ampeg style tube driven reverb using a high impedance tank. I noticed this tank [4FB3D1B] has an insulated input jack and an insulated output jack. The amp has grounded chassis jacks and vintage style cables. The reverb is quiet (no hum), however, should the tank chassis itself have a separate ground for any reason? Anybody familiar with what Ampeg did in the Reverberocket?
4FB3D1B- Long (16 ¾") 2 Spring Unit , Long Decay (2.75 – 4.0 seconds)
- Input Impedance 1475 Ohms, Output Impedance 2250 Ohms
- Input Insulated/Output Insulated
- Horizontal, Open Side Down Mounting Plane
Compatible Amps Include: Common replacement for Type C Ampeg® tanks plus others
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Is it working happy? Then the signal is fine.
Is there a slight background buzz? Run a cliplead from tank to amp chassis-- is that the fix? Then run a wire. Yes, you could get an un-insulated jack tank and save a penny, but in DIY we do what is convenient for the parts in hand.
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Is it working happy? Then the signal is fine.
Thank you, Sir. I thought that might be the case.
After some further research on the web, I found out you can change the grounding of the jacks by adding or removing a solder bridge. (https://bmamps.com/v01/wp-content/uploads/2017/10/How-to-Reverb-Tanks.pdf)