Modified Silvertone Model 1421 Amp – Part One, The Tear Down

Sears 10XL Silvertone 1421 Original Speaker and Baffle

From the tail end of the vacuum tube era, a real Tone Gem in the genre of garage band tone.

Editor’s Note: This is Part One of a two part series on modifying the Silvertone 1421 guitar amp. This article is a work in progress, so please check back for additional info and updates.

The 1960’s Silvertone 1421 Combo Tube Amp (also originally sold as the Sears 10XL) is a great little vintage tube amp. It’s compact size makes it easy to carry to practice or a to small venue. It’s low 10-watt tube output (actually, closer to 5-watt) is perfect for the recording studio. It has two instrument inputs going into one channel, volume and tone controls, and a fantastic 12AX7 tube tremolo circuit, playing out to an 8-inch speaker. The sound here is definitely in the garage band category, but you can coax some great sounds out of this little guy.

The all-tube version of this amp was made from 1968 to 1972, and was later replaced with a all-transistor (solid-state) version in 1973. I picked this one up off eBay a few years ago. It’s a 1970 model and is all original, except for the brown speaker grille fabric (which is ugly!).

Below is a photo of my Silvertone 1421 after it first arrived. The vinyl covering, the controls, the faceplate were all in excellent condition for its age; no tears or scratches. The original vinyl handle was flexible and intact. The only problem this amp had was a stuck (frozen) power switch. I replaced the bad switch with a new heavy-duty toggle, and replaced the old two-prong power cord with a new grounded cord. When I powered it up for the first time it was amazingly quiet for an old tube amp.

1970 Sears 10XL Silvertone 1421

The knobs and faceplate were in great condition. The handle was still flexible and firmly secured to the cabinet. But the original toggle switch stuck (frozen).

1970 Sears 10XL Silvertone 142 Control Panel
1970 Sears 10XL Silvertone 142 Control Panel

Front view showing the replaced grille cloth over the original baffle board and speaker.

Sears 10XL Silvertone 1421
Sears 10XL Silvertone 1421 Front

Rear view of cabinet. You can see the new grounded power cord that I added.

Sears 10Xl Silvertone 1421 Back Cover
Sears 10Xl Silvertone 1421 Rear

The Sears product label on the rear panel showing the model number and vacuum tube layout.

Sears 10XL Silvertone 1421 Label
Sears 10XL Silvertone 1421 Label

A view of the chassis through the back panel vent.

Sears 10XL Silvertone 1421 View of Chassis
Sears 10XL Silvertone 1421 View of Chassis

Photo of the cabinet interior, showing the chassis and the original 8-inch speaker made by CTS.

Inside Sears 10XL Silvertone 1421
Inside the Cabinet

A closer view of the chassis.

Sears 10XL Silvertone 1421 Chassis and Speaker
Chassis and Speaker

The 8-inch speaker with ceramic magnet made by CTS (code 137).

Sears 10XL Silvertone 1421 Speaker
Sears 10XL Silvertone 1421 Speaker

Another view of the chassis, showing the power transformer, the filter capacitor can, the output transformer, and the tubes. The on-baord tube complement is one 6X4 Rectifier tube, two 12AX7 tubes for preamp and tremolo circuits, and 7189 power tube.

Chassis and Tubes
Chassis and Tubes

Here is the baffle board removed from the cabinet. The board was nothing more than 1/8″ thick Masonite.

Sears 10XL Silvertone 1421 Baffle
Sears 10XL Silvertone 1421 Baffle
Sears 10XL Silvertone 1421 Original Speaker
Sears 10XL Silvertone 1421 Original Speaker
Sears 10XL Silvertone 1421 Original Speaker and Baffle
Sears 10XL Silvertone 1421 Original Speaker and Baffle
Sears 10XL Silvertone 1421 Original Speaker and Baffle
Sears 10XL Silvertone 1421 Original Speaker and Baffle

Here is the cabinet with the baffle board removed.

Sears 10XL Silvertone 1421 Front Baffle Removed
Sears 10XL Silvertone 1421 Front Baffle Removed
Sears 10XL Silvertone 1421 Back Cover Removed
Sears 10XL Silvertone 1421 Back Cover Removed

The wiring is hand-wired and soldered.

Sears 10XL Silvertone 1421 Chassis
Sears 10XL Silvertone 1421 Chassis
Sears 10XL Silvertone 1421 Chassis Components
Sears 10XL Silvertone 1421 Chassis Components
Sears 10XL Silvertone 1421 Chassis Components
Old School Resistors and Capacitors
Sears 10XL Silvertone 1421 Chassis Components
Orange Drop Cap and Fuse Assembly
Sears 10XL Silvertone 1421 Chassis Components
Orange Drop Capacitor
Sears 10XL Silvertone 1421 Chassis Components
Old School “Chiclet” Capacitor
Sears 10XL Silvertone 1421 Chassis Components
Sears 10XL Silvertone 1421 Chassis Components

Silvertone 1421 (Sears 10 XL) Guitar Tube Amp

Sears 10XL. Silvertone 1421.


NOTE: This great little amp now resides happily with its new owner in Charleston, South Carolina.

Vintage 1971 Sears 10 XL Silvertone 1421 Combo Guitar Tube Amp

The Sears 10 XL was sold through Sears and Roebuck in the late 1960’s and early 70’s. The 10 XL is a single channel, 10-watt (peak) combo amp for electric guitar with a very cool built-in tube-powered tremolo effect.

This little amp first appeared in the 1969 Sears Catalog as a 10-watt tube-powered amp and, transformed into to a solid-state amp around 1972, and then discontinued in 1973. The label on the rear panel identified this model as Silvertone 257.1421100.

The photo of this little amp looks innocent enough. But don’t let the its appearance fool you! This is a serious sleeper of a tube amp, and sounds fantastic. Perfect for your next garage band. And you won’t usually find them as nice as this one!

Quick Info

Summary: A 10-watt tube combo with tremolo and 8-inch speaker. Hand-wired. Lots of midrange growl that transitions into a saturated overdrive. Great for classic and indie rock, jazz, blues, country and rockabilly. Use as a practice amp or at small venues. Perfect for recording.

Pluses (+): Vintage 1960’s tube sound in an affordable practice amp package. Compact and lightweight.

Minuses ( – ): Lightweight constructed cabinet and vinyl covering (it’s a Sears amp!). The original fabric grille cloth was fragile, and therefore most are completely deteriorated by now. Not really loud enough for a big venue, but still perfect for those small and intimate gigs (i.e. coffee shop).

Surprises ( ! ): 1) The 7189 output tube! This is the higher plate voltage version of the EL84 tube found in famous British valve amps of the 60’s; and 2) The 8-inch Oxford Alnico speaker sounds great!

Value ($): Depends on the condition and market demand. I have seen them run from $100 (beat up and not working) to as high as $500 (too much!).

Similar Amps: Unique, nothing else in the Silvertone line is similar. Preamp tube (12AX7) and power tube (7189 version of EL84) used in the 1960’s Vox AC4.

The Sears XL Story (as best I know it)

Sears 1969 catalog, page 928, guitar amplifiersThe Sears 10 XL was a member of the Sears XL Series of amplifiers that first appeaed in the late 1960’s and ran through the mid-1970’s. The XL Series followed the venerable Silvertone 1400 Series (1472, 1482, 1483, 1484, 1485) from the early to mid 1960’s. The XL Series ranged from the little 5 XL (3-tubes, 3-watts) to the giant 200 XL (200-watts solid-state).

Before the XL Series, the Sears Silvertone 1400 line up of amps was designed and built by the famously efficient and economical Danelectro Company of Neptune, New Jersey. Danelectro was founded by the pioneering electronics engineer and builder Nathan Daniel. Nate Daniel specialized in building quality musical instruments and gear at reasonable prices. Danelectro built and supplied all the guitar amps to Sears and Roebuck from about 1958 to 1968. In 1966 founder Nate Daniel sold his company to MCA, and unfortunately by 1969, MCA had to shut down the operation and thus the original Danelectro Company no longer existed.

From about 1968 to 1972 the smaller amps in the Sears XL Series (the 5 XL, 10 XL, 40 XL) continued to be hand-wired tube amps. But by 1973 the entire XL line – except for the little 5 XL – had transitioned to all solid-state electronics. Exactly who built these XL amps for Sears remains a uncertain. We have speculated that the 5, 10 and 40 XL’s were still built in New Jersey with left-over parts from the defunct Daneletro.

The Chassis

The chassis of the 10 XL is all hand-wired point-to-point electronics with a 6X4 tube rectifier, a 12AX7 preamp tube, a 12AX7 tremolo tube circuit and a single 7189 output power tube. The amp has volume and tone controls, Tremolo speed and intensity controls, two 1/4″ guitar input jacks, and one 1/4″ tremolo foot switch input jack.

The Speaker

The loudspeakers that came in the Sears 10 XL varied throughout production. All speakers were 8-inches in size. But the manufacturer and type of speaker varied. This particular model has an 8-inch speaker made by Oxford with an Alnico magnet, which perfectly compliments the lower output level of the 7189 power tube, and sounds great in this amp. Some other 1421 models were made with speakers from the CTS or Fisher factories, and by my account, those all had ceramic magnets instead of Alnico.

The Baffle Board and Grille Cloth

The baffle board is typical Silvertone quality: 1/8″ pressed board (Masonite). That just helps to establish this amp’s personality. The original silver, gold and green sparkle fabric that covers the baffle board is quite delicate, and in most cases rotted away over the years. Thankfully, somehow the original fabric survived on this model.

The 10 XL Photo Gallery

This 10 XL is in fantastic condition for it’s age. It even came with the factory original vinyl dust cover and tremolo foot switch. It is all original, except that I replaced a broken power switch, and then replaced the old 2-prong power cord with a safer grounded cord. The tubes, chassis, speaker, cabinet and finish are all in perfect condition — sans for the cigarette-sized hole in the original grille cloth (not by me, it came that way!).

Specifications – Silvertone 1421 (Sears 10XL)

SEARS 10 XL (SILVERTONE 1421)
Model Number 257.14211000
Serial Number None
Manufacture Date April 1971
Type 8″ Combo
Output (Peak or RMS) 10 Watts, Peak
Pre-Amp Tube(s) 1 x 12AX7
Tremolo Tube(s) 1 x 12AX7
Power Amp Tube(s 1 x 7189
Tube Rectifier 6X4
Speaker Oxford 8″ Alnico
Speaker Code 465-7118
Speaker Configuration 1 x 8″
Baffle Board 1/8″ Masonite
Impedance 4 Ohm
On-Board Effects Tremolo
Footswitch Yes
Controls Volume & Tone
Inputs 2
Channels 1
Cabinet Construction 3/8″ Pressed Board
Cabinet Covering/Color Vinyl / Black
Dimensions (WxHxD) 14″x17″x6″
Weight 10 lbs.
Power 120V AC

Schematic for Silvertone 1421

Schematic for Silvertone 1421
Silvertone 1421 Schematic Courtesy of Schematic Heaven

Additional Resources

Links to additional information.

More info to come…

Previous comments

{ 5 comments… read them below or add one }

dave carter June 8, 2012 at 4:06 pm

have one in perfect condition,with the foot petal.no dust cover.ready to sale

REPLY

b d brown February 2, 2013 at 6:10 pm

the other maker of sears guitar amps was electrnic sound corp of chicargo ill during the 1970s to about the late 80s. they used oxford, and quam speakers and maybe cts or some utahs. the also made cabents for the game manufactuers wiaims/bally/ etc.

REPLY

alex February 3, 2013 at 9:03 am

That’s great info! Thank you. I will look into that further… ~alex

REPLY

alex February 3, 2013 at 9:11 am

The Silvertone 1420 (Sears 5XL) is identical to the older Danelectro built model 1459. After Danelectro was no more, do you think maybe they built the 1420 for Sears from old Danelectro parts, or maybe just copied the Dano design? ~alex

Link: http://www.tonegems.com/sears-5-xl-amp-silvertone-model-1420/

REPLY

Allan Kidd July 25, 2013 at 12:50 pm

looking for schematics for sears 1422/ 40XL Tube amp

REPLY

Two Silvertone Amps + Boss CE-3 = Stereo!

Boss CE-3 Chorus

I love stereo! That’s why I got pretty excited when I looked at my Boss CE-3 chorus pedal and realized I could connect a pair of amps to the CE-3′s dual outputs and play my guitar in stereo. So I decided pick up two inexpensive Silvertone 1421′s (aka: Sears 10XL) off eBay. These are great little tube amps from the late 60′s and early 70′s. The 10-watt 1421 uses two 12AX7 tubes—one for pre-amp and the other for tremolo—and a single 7189 as the output tube. The 7189 tube is the industrial version of the venerable EL84, a tube found in so many British valve amps. The 12AX7/EL84 tube combination is unique to the 1421 amp within the entire Silvertone line, and compares it nicely by design to the original Vox AC4 Combo of the early 60′s.

Sears 10XL. Silvertone 1421.This first amp is a beautiful 1971 model, completely original and in excellent condition. The Sears model number is 257.14211100. It probably sat in someone’s closet for the better part of 30+ years and was hardly played. Except for a power switch stuck in the “on” position, the old two-conductor power cord, and a little bit of hum, this combo is totally functional and sounds great. It even has its original protective vinyl cover (I’ve never seen a cover for these before) and its original tremolo foot switch. The original grill cloth is in great condition, which is truly rare for this model, even though it does have one cigarette-sized hole in the fabric. The speaker is an 8-inch Oxford Alnico magnet speaker that rings clear at low volume, but breaks up nicely when cranked (along with the tubes in overdrive). All in all, this little combo is a real sweet find! After I fix the power switch and replace the cord, I plan to keep this guy all original. I can live with a little hum for now.

Sears 10XL Silvertone 1421
Sears 10XL Silvertone 1421 Front

The other amp is a 1970 model 1421. Also Sears model number 257.14211100. It’s in pretty good condition too, and is almost completely dead quiet (no hum) when running. But the original grill cloth was replaced and the tremolo is not working. Somebody already replaced the notorious power switch and the 2-prong power cord before I bought it. Unlike it’s twin, this 1421 has an 8-inch CTS speaker with ceramic magnet. I plan to mod this amp as my next project. I will need to work on the tremolo circuit, then replace the caps, ditch the ugly brown fabric, and build a new baffle board to hold a bigger 10-inch Alnico Blue speaker (think: Celestion). After those mods are complete, this 1421 should sound more British than American.

Then, plug these two into my CE-3 stereo chorus pedal and have fun!

A full Tone Gems review of the Silvertone 1421 will be in the near future.