Alrighty
So I have attempted to do an updated schematic in terms of how the reverb circuit looks, with some notes, to try and make it easier for anyone who wants to replace the stock reverb in the Silvertone 1484 with a transformerless tube / current driven reverb using minimal parts and minimal changes to the existing circuit. When you take a look, you can see it takes minimal changes. The cost of the new reverb tank is the biggest. Total cost of this mod is around USD$30 if you do it yourself. Other bits are simply RCA connectors, a few caps and resistors.
So far this is what I have:
https://www.dropbox.com/s/amj34ls9zb...%2015.jpg?dl=0
I think I have captured everything thus far. Lines and text in red are changes or additions to the stock circuit. Keen on any input you might have. Wanting to get this right so others can relatively easily follow it.
I have installed the 100k grid stopper resistor on the audio in - this didn’t make much difference to the reverb control dropping audio at full. Thought it might be some sort of oscillation so installed a shielded cable run for the reverb audio in and this solved the issue.
I then put a 0.002 if across the 220k resistor and a 2.2uf/63v across the 10k resistor - and voila, the reverb works and sounds great. So mission accomplished!
Let me know of any suggested changes to the diagram so I can finalise for use by others.
Before I stitch it up I’ll go through and do a final voltage check - and check the bias on the tubes. Still can’t help but feel it should be louder. I have a 25w Supro that is quite a bit louder.
So I have attempted to do an updated schematic in terms of how the reverb circuit looks, with some notes, to try and make it easier for anyone who wants to replace the stock reverb in the Silvertone 1484 with a transformerless tube / current driven reverb using minimal parts and minimal changes to the existing circuit. When you take a look, you can see it takes minimal changes. The cost of the new reverb tank is the biggest. Total cost of this mod is around USD$30 if you do it yourself. Other bits are simply RCA connectors, a few caps and resistors.
So far this is what I have:
https://www.dropbox.com/s/amj34ls9zb...%2015.jpg?dl=0
I think I have captured everything thus far. Lines and text in red are changes or additions to the stock circuit. Keen on any input you might have. Wanting to get this right so others can relatively easily follow it.
I have installed the 100k grid stopper resistor on the audio in - this didn’t make much difference to the reverb control dropping audio at full. Thought it might be some sort of oscillation so installed a shielded cable run for the reverb audio in and this solved the issue.
I then put a 0.002 if across the 220k resistor and a 2.2uf/63v across the 10k resistor - and voila, the reverb works and sounds great. So mission accomplished!
Let me know of any suggested changes to the diagram so I can finalise for use by others.
Before I stitch it up I’ll go through and do a final voltage check - and check the bias on the tubes. Still can’t help but feel it should be louder. I have a 25w Supro that is quite a bit louder.
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