Output Transformer/Reverb upgrade for Sears Silvertone 1484

[WolfElectric]

So... ive been doing some research for the Sears Silvertone 1484 im about to
aquire

im in a band (Wolf Electric... www.facebook.com/WolfElectricMusic) and even
tho i have tried one of these amps out briefly (and fell in love) a few
years ago im alittle concerned whether im going to be able to keep up with
the rest of the decibels my bandmates will be pushing out.

i hear these the output transformers in these amps will be (as ive
researched) about 30 watts (even though specs say 50 watts)

i want to make this amp a true 50-60 watt amp... how can i do that?

is this even a realistic request???

i love the tone of these amps when they are clean (and of course with a fair
amount of breakup but more clean)

the one im about to be getting has stock everything, but i wanted to see if
there was any way i could make the amp louder and cleaner.

eventually i think i may put in the same speakers that are in a twin reverb (Jensen C12N?)
to have alittle more clarity (headroom?)

but for the volume push, if i replaced the output transformer with one that
put out higher watts...
is this how i make my amp louder?
if so, what specific transformer would you suggest?
i dont want to fry anything by placing something in there thats not
supposed to be there so is there anything else i should replace so the
transformer wont ruin anything else in my amp???

how can i make this amp louder and cleaner???

ive spent alot of time using a 59 fender bassman reissue several years back
and it was definetely loud enough to keep up with my band then, and tho the
watts on both amps are the same in writing, can i really make my amp louder?

cant wait to hear what you think

if you cant answer my question, know of anyone who can?

hope to hear back soon.

P.S.

know any way to successfully mod these amps to have fender style
reverb??? ive only seen this one time online but the guy who had it bought
it that way and didnt know who did it or understood it well enough to
explain how....

any info back would be great

[blackbunny]

Why not just get an amp that has the features you want? Sounds like you will have to replace the output transformer, mains transformer and power supply filter caps, plus try and squeeze a reverb tank and circuitry in there somewhere, to get close to what you want.

I rebuilt one of these Silvertone 1484 amps for a chum, who loves its sweet midrange and lo-fi overdrive when pushed hard. The small output transformer and low-current voltage-doubler HT supply, with relatively small filter capacitors, make for 25 or so lovely "vintage voiced" watts.

You should sell it to someone who enjoys what it is, and get a 50-60 watt amp with reverb.

[mysticwhiskey]

I gotta agree with blackbunny here. You're probably better off getting an amp that has the features and the sound you're after, rather than extensively modifying an amp into something it's not, IMO.

[Greenmachine]

If you do a search here for "Silvertone 1484 Guts" you'll find a thread about some work I did to this unit. I stuck a Fender replacement OT for a Hotrod Deluxe (40 watts?). I'm pleased with the results - it's very loud as well. Can't give you a wattage number though.

I think the advice given above is sound. I didn't even touch the reverb section and the work I did in that dense rat's nest took a long time. Just so you know what you're getting into. Furthermore, you'll rack up a parts bill for sure.

[RnFR]

i know people change the transformers in these things a lot, as they are underpowered and fail quite often. it shouldn't be that hard to find some info. as far as the reverb goes, why not just try replacing the tank with a fender type unit?

[blackbunny]

I replaced a blown output TX a few years ago with this Weber output transformer, which sounded very good:

https://taweber.powweb.com/store/ot1484sch.jpg

Similar to the stock one, but a bit more clean headroom and not as fragile.

I repaired another 1484 recently, using a Heyboer Tweed Bassman output trannie which sounded noticeably cleaner and louder. The power supply sags well before the new 40-50 watt output TX, and it is very difficult to upgrade the filter caps to 220uF / 150V due to tight layout. I ended up fitting a new Heyboer 50 watt mains transformer and was able to configure the HT supply as a conventional full wave rectifier, which made room for bigger power supply filter capacitors.

It took a lot of work, but the owner is happy with the new louder, cleaner sound, which still has some sweet Silvertone character when cranked.

The 1484 schematic shows the dual secondary HT windings / capacitor charged voltage doubler configuration using C26-29, which effectively results in a 25uF / 600 VDC HT filter capacitor. This defines the way the stock power supply behaves, and enhances that "saggy vintage" response.

Good luck trying to get the reverb circuit to sound like a Fender....it's a completely different animal.

[DrNomis]

How hard would it be to "clone" one of these amps from the schematic, but instead of using the original construction techniques, build all the circuitry on either Tagboards, or Eyelet boards?, I'd imagine that it would be feasible, provided that suitable "iron" (Power and Output transformers) can be found...

[blackbunny]

It shouldn't be too hard to build one of these on tagboard or eyelet board as you propose.

The original has a kooky layout aptly described by Greenmachine as a dense rat's nest, using tag strips and masonite (pressed hardboard) eyelet boards squeezed into an aluminium U channel thingy, with some spectacularly long wiring runs between the DC filters and the preamp valves. I reckon you could design a neater layout than Silvertone used.

I've never seen a stock 1484 that puts out more than 25 watts RMS into a 4 or 8 ohm load, which I think is a result of too-small power and output trannies, and they have a reputation for blowing the trannies, so you could definitely improve both the power and the reliability with some quality iron.

[DrNomis]

It shouldn't be too hard to build one of these on tagboard or eyelet board as you propose.

The original has a kooky layout aptly described by Greenmachine as a dense rat's nest, using tag strips and masonite (pressed hardboard) eyelet boards squeezed into an aluminium U channel thingy, with some spectacularly long wiring runs between the DC filters and the preamp valves. I reckon you could design a neater layout than Silvertone used.

I've never seen a stock 1484 that puts out more than 25 watts RMS into a 4 or 8 ohm load, which I think is a result of too-small power and output trannies, and they have a reputation for blowing the trannies, so you could definitely improve both the power and the reliability with some quality iron.

Maybe that might be a good idea for an amp project for FSB then, there's projects for stompboxes, why not amps too?, maybe modman might be interested in setting up a forum thread?...

[KindaFuzzy]

After seeing Greenmachine's amp I was going to work on a 1484 lite sort of thing as my next ammo can project, once I finish the latest 213 clone. I've only done rough sketches of the schematic I'd use, but I was going to ditch the reverb, make it a 6v6 or similar output and put a heater switch on the PI tube so you could use the stock 6cg7, or a more available 12au7. I wonder if anyone would be interested in that as a FSB project.

[DrNomis]

After seeing Greenmachine's amp I was going to work on a 1484 lite sort of thing as my next ammo can project, once I finish the latest 213 clone. I've only done rough sketches of the schematic I'd use, but I was going to ditch the reverb, make it a 6v6 or similar output and put a heater switch on the PI tube so you could use the stock 6cg7, or a more available 12au7. I wonder if anyone would be interested in that as a FSB project.

You could even take the stock 1484 circuit and make it into a combo amp, something like a Fender Twin for example, I wonder why they chose a 6CG7 for the PI Tube, instead of the usual 12AU7, 12AT7, or 12AX7?, could it be that it was an easy/cheap to get tube?, or maybe they were aiming for a low gain-structure to give relatively clean sounds?, the idea of using 6V6 tubes instead of 6L6 tubes is cool, this would enable you to reduce the size of the chassis a bit Í'd imagine....

[RnFR]

After seeing Greenmachine's amp I was going to work on a 1484 lite sort of thing as my next ammo can project, once I finish the latest 213 clone. I've only done rough sketches of the schematic I'd use, but I was going to ditch the reverb, make it a 6v6 or similar output and put a heater switch on the PI tube so you could use the stock 6cg7, or a more available 12au7. I wonder if anyone would be interested in that as a FSB project.

I would. I've been thinking of doing a stripped down single channel version of this for a while. I even went so far as to draw up a tagboard layout for the pre. I might still have it at home.

[blackbunny]

I wonder why they chose a 6CG7 for the PI Tube, instead of the usual 12AU7, 12AT7, or 12AX7?, could it be that it was an easy/cheap to get tube?

6CG7's were cheaper than the new-fangled 12AT7 or 12AU7 tubes at the time (early 60's) when this amp was released. It was a cheap amp from the budget Silvertone line, so component costs were kept to a minimum. They only used expensive 12AX7's for the high gain / low noise stages.

I've been thinking of doing a stripped down single channel version of this for a while. I even went so far as to draw up a tagboard layout for the pre. I might still have it at home.

It would be great if you could post it here to get us started.

I know it sounds a bit perverse, but after repairing / bulletproofing a few of these amps over the years, I would build a "vintage" version complete with saggy power supply and small output transformer for that "midrange magic" tone.

Would probably use Fender Deluxe Reverb-style mains and output transformers from Weber or Heyboer for better reliability.

Between 320 and 350 VDC HT for 6V6's and 340-380 VDC for 6L6's will make a great-sounding 1484 clone, and the small Deluxe Reverb-style output transformer will live longer with 6V6's than it will with 6L6's.

[phatt]

The power stage is not much different to the *Australian built * Goldentone Amps* built by *Charlie Mutton* in the land downunder many years ago.

Screen is *Half* the HT supply!!!! Makes for a wonderful output stage that compresses nicely

The never much mentioned way of attaining power stage compression!!! very kool.

Checkout *Goldentone Amps* on AVA site ,, http://www.ozvalveamps.org.
Run by a wonderful chap who has collected a whole mass of info on old Aust and NZ Amps.

Have fun ,,,Phil.

[blackbunny]

Checkout *Goldentone Amps* on AVA site ,, http://www.ozvalveamps.org.
Run by a wonderful chap who has collected a whole mass of info on old Aust and NZ Amps.

Roly's Ozamp site is indeed a wonderful source of info. It has helped me with many repairs & rebuilds of old Aussie amps, and the odd Holden Wasp and Jansen too.

The power stage is not much different to the *Australian built * Goldentone Amps* built by *Charlie Mutton* in the land downunder many years ago.

Screen is *Half* the HT supply!!!! Makes for a wonderful output stage that compresses nicely

It's a great power supply design for guitar amps, variations of which are also used by MusicMan, Moody, and Eminar in their 120 and 150 watt valve amps from the early to mid 70's.

The Silvertone & Eminar used 2 different HT secondary windings that result in the screen voltage being about 60% of the HT plate voltage, and the MusicMan fed the screens from mid-point of the HT supply, resulting in 50% of B+.

[jobpro]

For sale one Sears Silvertone Twin Twelve 1484, call 785 398 2296 or email jobpro@gbta.net thank you.

[DougH]

You will not increase the output power of an amplifier by using a different output transformer.