Silvertone 1482 Amp - Dull Tone

[Knave101]

A few thoughts on a refurb I just did...

I've got a new mid 60's Silvertone 1482 Amp, in near new condition. Original Speaker. Upon purchase I do my usual three things I do to all my amp refurbs:

1. Replace Electrolytic Can Cap, with 3 individual new caps. The orig can has 20uf/450V, 10uf/450V, and 5uf/450V. I installed a little vertical oriented Terminal Strip using a screw that holds the output trans. I use 22uf/500V for the first, then 10uf/450V for the next two. Replaced the 2.2k and 27k resistors voltage step-down 1/2 W resistors with 1W resistors. As can be seen from almost every video posted....the 2.2k 1/2 original Carbon Comp Resister that steps down voltage and goes from the first to second lug of the Capacitor can...Always is burnt up on this amp.

2. Replace power cord with 3 wire grounded cord. I always also put in a thermal inrush current limiter. In this case, I used a 120ohm, 2A inrush limiter. The black (hot) wire goes to top of fuse holder, then current limiter from ring of fuse holder to power switch. Then from power switch to Power Trans input. The white wire is directly connected to the other power Trans input wire. Green to chassis. As is listed in many diagrams, when replacing the power cord...fuse, current limiter, and switch are on the hot wire...in that order. All modern amps from Fender, including hand wired models...use current limiters, so do I. If you measure the voltage rush, these can hold down the peak, particularly on SS rectified amps....so the voltage doesn't exceed the Electrolytic capacitor limits on startup.

3. Then, after testing, I noticed the amp sounds dull, even on full treble. There is no reason for this as the circuit is quite simple. So, I replaced all the 0.01 uf "648" Dark Orange drop film coupling capacitors with new Polyester film Caps (there are 5). Original caps from the 60's were not polypropylene...so I use Polyester. While, I am not sure if these orig caps go bad, it is possible from moisture absorption that they do change for the worse. I've noticed when I rebuilt my old tube echoplex and replaced all the vintage orange drops that the echoplex sounded incredibly clearer with same value polypropylene caps.

Test #2: I have to say that the amp sounds clearer with better sparkle with the new polyester coupling caps. Would be interested to hear others opinion on this. I left the values at 0.01uf as original.
If I were to do it again, I would use recommend Polypropylene rather than polyester coupling caps. Why? because the amp is somewhat dull sounding with the original caps, and that's what I'm trying to fix here. You are running through three sequential iterations of coupling though the caps...2 in the preamp, and 2 in push/pull in the power section. Each amplifies the shortcomings of the one previous. Since, I'm trying to brighten the tone, I would go polypropylene to clear up the tone as much as possible.

Speaker: I also believe that this speaker is likely a dog as well. I would love to put in a nice alnico replacement, but fear it would not fit the cabinet. I usually use Celestion Ruby, Blue or Gold alnicos....but they're getting very expensive...so for now I'll leave the original. I'm sure the Celestions wouldn't fit anyways. Has anyone tried the Warehouse 12" Alnico British speaker....they are less expensive? It wouldn't fit here either unfortunately. So maybe a modern Jensen alnico, without any bell housing might fit.

Tremolo Circuit: I didn't change anything here. The 3 phase changing caps are ceramic and work fine...so I left them as they are. I've seen some videos where people change these...not sure why if they work stock?

Lastly: This amp truly shines when you plug into the instrument input, and then use a jumper to also plug into the 'microphone' input as well. The two inputs go into either half of the first 12AX7 and are then summed together into the first half of the second 12ax7. With the added gain, then this amp is awesome, with great overdrive breakup at not too loud volume. This is the magic of this amp, and why it's a keeper.

 

[Boreas]

Old Silvertones are great amps that were never really appreciated in their day. Not without their foibles, but a very sweet tone. Uncle Doug has a few videos on servicing them.

 

[FortuneTele]

If it has a Fisher (1056 mfg code) speaker, that might be part of the dullness.

 

[Knave101]

I tried the amp using my Celestian Ruby Alnico, and to be honest it didn't sound as different as I thought it would, compared to the Fisher alnico speaker. I then compared the amp to my Princeton Hand Wired Stapleton amp (with the same Ruby speaker) and realized the Princeton definitely has a lot of lows filtered out....so I went ahead and decided to put in a "bright cap".

The "Bright Cap"....per Rob Robinette's site, goes across the Instrument Volume Pot....I tried a few and settled on a 560pf cap, and replaced the 3000pf ceramic tone cap with a polyester 4700pf cap. This makes a significant difference at lower volumes, wipes away the much of the "Dull".

Now the amp has the bright cap on the instrument channel, remaining stock in the Mic channel. I can mix in the unchanged Mic channel via the channel jumper, and it is truly an incredible sounding amp....I hate to say....better than my $$$ hand wired Princeton!

 

[Knave101]

Regarding Speaker Replacement Information, and my desires to replace the Fisher speaker:

There is exactly 5" speaker clearance from front baffle panel to the back wood panel. The original 12" speaker height is 4 7/8"...barely enough room.

This is important for anyone looking to replace the speaker. So, for instance, the Jensen P12Q is 5.4", Jensen P12R is 5.2" and won't fit. I'm seeing no Alnico's that will work. Jensen ceramics will work. So, for now, the Fisher will stay.

 

[muscmp]

i've had a 66 and 67 1482. sold the 67 a couple years ago. i bought it for a good deal on CL and did the cap can as well as other needy caps and resistors. it had the fisher speaker also. i compared the two and found them to sound almost exactly the same whether i was playing guitar or harp. never considered either to have a dull sound. it is all subjective. i sold the 67 to a harp player who was there and gone in 15mins., he loved the amp so much. it had the masonite staple baffle but it was tight enough that it didn't rattle. note that the cabs are not that quality either.

the 66 masonite had the masonite and did rattle so i bought some birch ply and had a friend route it for the speaker. it sure did solidify its sound. since it didn't have the original back panel, i made one with the leftover birch. these have some of the tremolo around. and, yea with the jumping of the inst. and mic channels, it becomes a completely different amp.
enjoy!

play music!

 

[Knave101]

I'll admit I think it sounds perfect now, with the two channels linked as I mentioned above. So, I'll keep the speaker as is. The 560pf bright cap really helped clean up the instrument channel. My baffle is in good shape, but the aluminum chassis vibrates in the front where the knobs are....as it's difficult to secure this side of the panel.
I'd love to say, I'm going to keep it forever....but forever is closer now than ever before....so soon everything will be for sale.

 

[Zepfan]

My 1482 is a curbside rescue. Original cab and tubes, speaker baffle had been changed to 3/8's" plywood. That probably helped, but the unit had been out on the curb for at least 12 hours and was wet. Pressed fiberboard cabinet material doesn't do wet.
My plan was to make a new cab, replace the old caps and maybe do a mod or 2. Meanwhile, I decided to mount the speaker and chassis in a old 3-way stereo speaker cab that I also found.
After mounting it all I was surprised to get awesome tone. Was it the pressed sawdust? Probably not, but who knows. I'm sure the cabinet dimensions had something to do with it and the glue infused sawdust may be better than wet fiberboard.
Still need to remove the chassis and do a re-cap, but for now the stereo speaker cab remains the home.
The Fisher speaker had a couple small holes around the edge made by a hungry mouse. Was going to replace the Fisher with a Cannibis Rex, but tried a repair job. Glad I did, the Fisher sounds awesome.

 

[Zepfan]

By the way, if you haven't already, replace your amp power cord with a 3 prong cord and remove the death cap.

 

[Knave101]

By the way, if you haven't already, replace your amp power cord with a 3 prong cord and remove the death cap.

Done already. Good find on your amp! I'm sure the cab is glue-pressed sawdust. I once found a tweed Harvard in someone’s snowy wood pile behind their garage. $20. New E-caps and it still works perfectly

Regarding the Silvertone 1482. I went ahead and replaced both channel ceramic 3000pf tone caps with 5400pf polyester modern caps. I also added a 400 pf "bright cap" to the volume pot on the "mic" channel, per the Robinette mod. Such that both channels have some of the very lows filtered when the volume is low. IMO this has greatly improved the amp, removing the mud....more than any other mod. I called the speaker a 'dog' early in the post....however, I now believe its actually a great speaker. The circuit just needed a tweek.

Last mod to consider is whether to replace the three 0.02uf ceramic tremolo caps. The tremolo was a bit too fast, so I added a 0.01 cap to the final .02 to slow it a tad. The tremolo circuit runs to the output tubes via a 0.047uf dark orange cap, and the circuit is filtered via a 0.5uf waxed tubular cap to ground.

So, I'm running my Peavey Rockmaster Tube Preamp into the amp....and it's great! Incredible tone.

 

[Zepfan]

When I was using my 1482, I was running the mic channel and the instrument channel together and that took care of the too dark tone, but I don't mind some darkness.
I use the tremolo at slow to mid speed most of the time, but it does get fast.

 

[Knave101]

Well, I liked the first amp so much, I acquired another.

I changed a few things:
1. Bias runs a little cooler, (about 78% 6V6 output) with a 300 ohm cathode resistor, than 270. I would have preferred a 330 ohm, but don't have any. These resistors run 1.5 Watts, so a 5 Watt rating is plenty. I changed the position of the bias resistor, as it's so cramped at the ground lug on the original Filter Cap. I moved it to the next 6V6 tube. The 300 ohm Resistor is the blue one in the photo below.

2. I moved the Inrush current limiter (2 amp, 120 Ohm) to the white, return wire then to PT, as is done on modern Fenders. In order to do this I put a mounting lug off one of the PT screws. The hot black still goes to fuse, then switch, then PT.

3. I left all the coupling caps original on the second unit....and it just doesn't sound as good. So I'll likely upgrade the .01uf caps throughout.

4. Again I replaced the 3000 pf tone ceramic cap with a 4700pf polyester.

5. Of course, I put in the 500pf 'Bright Cap'.....as mentioned in the Robinette pages, to tone down the low volume mush.

6. I slightly changed the positions of the Filter Caps from the first rebuild. I mount a vertical standoff on the screw of the OT. I now put the ground on the top most lug, so if a finger touches....it hits the ground prior to the high voltage lugs below....better to burn a finger than defibrillate the heart! The last 10uf cap I moved downrange to the preamp tubes where it is used in the circuit. I used a 33uf on the first cap, instead of the 20uf. (The 6X4 can handle 40uf I believe).

7. On unit 2, so far I've left the tremolo circuit as it was (the three 0.02uf Ceramic caps)....I'll test that once all coupling caps are changed out.

 

[knavel]

This thread is now the Silvertone 1482 repair journal blog. Hopefully it assists others over time.

 

[zook]

One of the limiting factors in th 1482 is the cabinet. It is rather shallow in depth. Once I plugged one into a deeper 1 x 12 cabinet and the result was astounding.

 

[Joemayline]

I was able to test drive several speakers in my 1482 many moons ago. Surprisingly, the one that sounded the best, and actually fit (just), with the back panel on was the stock, Fender labeled, Eminence from a Blues Junior. You can pick them up, used, all day long for under 50 bucks. Amp sounds killer with this speaker.