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Hello, I'd like to share some things I learned by experimentation with my Silvertone 1484 amp. I have not seen my particular modding approach to improving the 1484's previously unusable verb else where, not saying it hasn't been done just that I haven't seen it. The verb isn't exactly fantastic sounding now but it's at least usable, and better than stock IMO.
My 1484 was pretty sad before, burned output transformer, light rust all over the face plate, cabinet is wasted, but the chassis is very clean cosmetic wise. I installed an output transformer from a 50 watt vintage Randal amp. The transformer actually says "engineering sample" on it written in felt, so I have no idea who actually made it, but the measured impermanence was pretty close to the stock one so I tried it and it sounds fantastic.
Next came a complete filter cap and diode job. I got extremely lucky and found a NOS Aerovox can cap on ebay that was very close spec wise to the stock one, and exactly the same size physically, and I used 150 mf CDE's for the rest including the bias cap, and beefy 600V 3 amp diodes.
I sell vacuum tubes on ebay and as such I have access to a large collection of tubes of all makers to experiment with, and so my approach naturally went this direction and I experimented with anything that would swap in as far as brand and type, and this is what I found.
On this amp the following tubes will work in any of the preamp positions 12AT7, 6201, 12AU7. 5814, 5963, 12AX7, 5751 in order more or less from the least to most gain, and I tried them all in both V1 and V2. The results IMO were that Telefunkin 12AX7s in both positions provided the best sound as far as detail and timbre, or a Telefunkin in V1 and an Amperex Bugle Boy 12AX7 in V2 for a warmer tone, your mileage may vary.
Then I did some research and found out that a few cats were experimenting with the somewhat rare 12BZ7 tube for it's increased gain in the V1 position. So I managed to find just one, a Sylvania grey plate in my collection, and brother that was a big improvement. I then bought a black plate NOS Tung Sol but returned to the Sylvania. More gain and better tone all the way around than stock.
I followed the BZ7 with a Telfunkin smooth plate in V2 and black plate RCA 6CG7's along with an RCA black plate 12AX7 in the tremelo. Note that there is a slight raising of the noise floor with the BZ7 , but it was not objectionable IMO. For output tubes a Pair of NOS metal RCA 6L6 tubes hands down blew away everything else I tried. Nothing like 1940's vintage tubes. The detail, presence and timbre these tubes provide has to be heard. Simply amazing tone with a Strat which is the only ax I've tried on it.
Now onto the reverb. What I did here was use an RCA 12DW7, which is half 12AX7 and half 12AU7 in one tube. This worked very well because the 12AX7 triode is the verb input and the 12AU7 is the output which substantially lowered the gain of the circuit and that allows you to be able to crank the pot up to a much more usable level before it takes off into trash land. Then on a whim I mounted my reverb tank upside down on top of the springs instead of underneath thinking that since the springs hung one way since the 60's maybe with gravity pulling the other direction might change the sound, so i tried it and that was a further improvement.
Before the reverb was completely unusable, and after I use a little all the time now, and even with heavy stompbox distortion it sounds good. The tremelo on this amp sounds like God too BTW.
All I can say is try it you'll like it!
My 1484 was pretty sad before, burned output transformer, light rust all over the face plate, cabinet is wasted, but the chassis is very clean cosmetic wise. I installed an output transformer from a 50 watt vintage Randal amp. The transformer actually says "engineering sample" on it written in felt, so I have no idea who actually made it, but the measured impermanence was pretty close to the stock one so I tried it and it sounds fantastic.
Next came a complete filter cap and diode job. I got extremely lucky and found a NOS Aerovox can cap on ebay that was very close spec wise to the stock one, and exactly the same size physically, and I used 150 mf CDE's for the rest including the bias cap, and beefy 600V 3 amp diodes.
I sell vacuum tubes on ebay and as such I have access to a large collection of tubes of all makers to experiment with, and so my approach naturally went this direction and I experimented with anything that would swap in as far as brand and type, and this is what I found.
On this amp the following tubes will work in any of the preamp positions 12AT7, 6201, 12AU7. 5814, 5963, 12AX7, 5751 in order more or less from the least to most gain, and I tried them all in both V1 and V2. The results IMO were that Telefunkin 12AX7s in both positions provided the best sound as far as detail and timbre, or a Telefunkin in V1 and an Amperex Bugle Boy 12AX7 in V2 for a warmer tone, your mileage may vary.
Then I did some research and found out that a few cats were experimenting with the somewhat rare 12BZ7 tube for it's increased gain in the V1 position. So I managed to find just one, a Sylvania grey plate in my collection, and brother that was a big improvement. I then bought a black plate NOS Tung Sol but returned to the Sylvania. More gain and better tone all the way around than stock.
I followed the BZ7 with a Telfunkin smooth plate in V2 and black plate RCA 6CG7's along with an RCA black plate 12AX7 in the tremelo. Note that there is a slight raising of the noise floor with the BZ7 , but it was not objectionable IMO. For output tubes a Pair of NOS metal RCA 6L6 tubes hands down blew away everything else I tried. Nothing like 1940's vintage tubes. The detail, presence and timbre these tubes provide has to be heard. Simply amazing tone with a Strat which is the only ax I've tried on it.
Now onto the reverb. What I did here was use an RCA 12DW7, which is half 12AX7 and half 12AU7 in one tube. This worked very well because the 12AX7 triode is the verb input and the 12AU7 is the output which substantially lowered the gain of the circuit and that allows you to be able to crank the pot up to a much more usable level before it takes off into trash land. Then on a whim I mounted my reverb tank upside down on top of the springs instead of underneath thinking that since the springs hung one way since the 60's maybe with gravity pulling the other direction might change the sound, so i tried it and that was a further improvement.
Before the reverb was completely unusable, and after I use a little all the time now, and even with heavy stompbox distortion it sounds good. The tremelo on this amp sounds like God too BTW.
All I can say is try it you'll like it!
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