Kay Vanguard 704 with Vibrato

Kay 704 Vanguard Vibrato

“A Briefcase Full of Blues” – The World’s First All Solid-State Guitar Amp

Quick Info

Summary: 1965 5-watt solid-state combo amp with built-in vibrato effect; 8-inch Alnico speaker; seven Germanium transistors and five Germanium diodes. Point-to-point hand soldered. Perfect little amp for practice or recording.

Pros: Vintage 60′s tone. Extremely compact and portable design. Vintage Germanium transistors and diodes. Simple chassis layout.

Cons: Cheap, lightweight construction and paper-thin fabric covering (but hey, it’s lasted this long already).

Surprises: This old school amp designed more like a tube amp than a solid-state amp. The 8-inch Oxford Alnico speaker sounds great! Awesome vintage vibrato circuit.

Value: Street prices vary by condition and demand, but the price of these continues to rise.

Similar Amps: Kay 700, 705 and 706 of similar vintage. It’s possible, but not certain, that there may be some similar Kay-built amps with a Truetone (Western Auto) label.

Introducing the Kay Vanguard Series

In 1962, the Kay Musical Instrument Company of Chicago introduced the Vanguard line of guitars and amps. That new line included the Kay Vanguard Amplifier with Vibrato, Model 704 (Model No. K-704). The Vanguard 704, along with other Vanguard amp models 700, 705 and 706, were the world’s first mass-produced all-transistor (solid-state) guitar amplifiers. While some transitional hybrid amplifier circuits had previously existed, which paired solid-state electronics with traditional vacuum tubes, Kay was the first company to offer a full line of exclusively solid-state amps to market in ’62. The Vanguard 704 was part of that line and was frequently seen offered with the Kay Vanguard solid-body electric guitar.

A marketing advertisement from 1965 says that the K-704 was built with seven transistors and five diodes.

A Compact Design

In contrast to the heavy, boxy, amplifiers of the 1950′s, the engineers at Kay set out to create a new series of amps styled for the Modern Space Age. The new Vanguard Series was designed to be compact, lightweight, sleek in appearance. Finished in a rad two-tone pattern, the tapered vertical design had a top mounted control panel, and a cabinet barely deep enough to house the speaker and chassis. The new look was unique for a guitar amp of the day and remains unique today. However, the lightweight cabinet materials made it more prone to excessive wear and tear. Therefore, not many of these amps have survived.

The Controls

The Vanguard 704 features three instrument inputs into a single channel; a volume control and a tone control. The power switch is built into the tone control knob. The vibrato controls include speed, strength, and a jack for a foot switch. A sturdy brass handle is ready to go places.

Old Germanium, New technology, Old Circuit Design

What really makes the Vanguard 704 interesting today is its 1960′s Class A amplifier design and chassis layout. Since solid state technology was still relatively new at the time, the Kay engineers built the preamp, vibrato and the output circuits similar to the old tube circuits, except using Germanium transistors and diodes substituted for vacuum tubes. Because of this design the K-704 sounds akin to its tube cousins of the day. Based on traditional tube amp design of that period, the vacuum tubes were replaced in the hand-wired circuits with seven Germanium transistors and four diodes. The old Germanium transistors sound a little “looser” than the newer Silicon versions, which make them perfect for these low wattage amps. However, Germanium never could handle the heat and raw power of higher watt amps. But Germanium still has a following and is used in low voltage applications, like custom built effects pedals.

According to the pots, it’s a 1965 model. Completely original. A 5-watt wonder. It’s circuits and layout are traditional for the period, but seven germanium transistors and four diodes in place of the traditional vacuum tubes. A single front-loaded 8″ Oxford Alnico speaker. Not a whole lot of lower mid-range. But then again, no low end speaker flab either. The tone kinda reminds me of Led Zep. Mild overdrive at full volume from my Gretsch 5120 humbuckers. Growling, howling overdrive from my Silvertone 1445 with Teisco single coils.

Vibrato, CCR, and The Midnight Special

The vintage Germanium powered vibrato circuit stirs up a deep swirly tremolo that simply sounds awesome. The Kay Vanguard with Vibrato is perfect for nailing that stirring, swelling, sound that Creedence Clearwater Revival played on songs like The Midnight Special and Run Through the Jungle, and other great CCR recordings.

If you are a fan of that vintage 60′s and 70′s tremolo, then this effect alone was worth the price of this unit.

Features

  • Compact, ready-to-go “suitcase” design.
  • Two-tone fabric over wood construction.
  • Five watts output.
  • 7 Germanium transistors.
  • 4 Germanium diodes.
  • 8-inch Oxford “Heavy Duty” Speaker with Alnico magnet.
  • One channel.
  • Three inputs.
  • Vibrato speed and depth controls; foot switch.
  • Volume and tone controls.

Specifications – Kay 704

KAY 704 – VANGUARD with VIBRATO
Model Number 704A
Serial Number 9366
Manufacture Date 1965
Type 8″ Combo Amp
Output (Peak or RMS) 5 Watts, Peak
Pre-Amp Transistors 2N2613, 2N408 and 2N591 Ge PNP BJT, RCA USA
Vibrato Transistors 2 ea. 2N408 Ge PNP BJT, RCA USA
Power Transistors 2 ea. 2N545 Ge PNP BJT, Motorola USA
Speaker Configuration 1 x 8″ Rear Loaded
Speaker Oxford 8ES-9 Alnico Magnet
Speaker Code 465-510 (10th month of 1965)
Baffle Board 1/4″ Plywood
Impedance 8 Ohm
On-Board Effects Solid-State Vibrato
Footswitch Yes
Controls Volume & Tone
Inputs 3 Instrument Inputs
Channels 1
Cabinet Construction 3/8″ Plywood
Cabinet Covering/Color Fabric
Dimensions (WxHxD) 14″x17″x6″
Weight 8 lbs.
Power 120V AC

Schematic Diagram and Parts List for the Kay 704A

Original factory schematic diagram as photographed from inside the 704 chassis.


Original factory Bill of Materials (or, “parts list”) as photographed from inside the 704 chassis. Notice that transistors Q1, Q2, Q3 and Q4 are all Germanium transistors made in the USA by RCA and Motorola, as well as diode D1.

Additional Resources

Links to additional information.

Photos: See more photos here.

Comments

weldon January 1, 2014 at 12:04 am

i had a 704 kay amp and kent guitar in the 60s they were new—–i had to pawn them to move away–i found a kent guitar and now looking for the amp-can you help thanks weldon bent

REPLY

alex January 1, 2014 at 9:13 am

Weldon,
Thanks for stopping by the website. 704 amps are hard to come by these days. Not many survived the 1960′s. Ebay is probably your best bet, as I see a few show up there each year. Craigslist another option. Good luck!
~alex

REPLY

big gee February 1, 2015 at 1:56 pm

I have one of these 704 Kay in great condition for sale make an offer

REPLY

Tom J April 7, 2015 at 4:28 pm

I have a Heater II reverb amp type 58 with the tag that says “Manufactured by beautiful girls in Milton, Wis.
under controlled atmosphere conditions”.
Can you help me get a schematic ?

REPLY

alex July 26, 2015 at 9:58 pm

Hi Tom.
That reverb unit was made by OC Electronics and was used in many amplifiers sold by Sears, Wards, etc. in the late 60′s early 70′s. I don’t know if a schematic is available, but you might try Schematic Heaven.

REPLY

Kalamazoo Model 1 Solid State Guitar Amp

Kalamazoo Model 1 Solid-State Guitar Amp


A great little clean tone amp with real vintage vibe. Why practice on a modern digital piece of (insert your favorite phrase here) when you can play a pure analog classic on the cheap!

Here’s a great little solid-state analog-powered practice amp for electric guitars. Around 5 to 10 watts of power into a vintage 10″ American speaker with Alnico magnet. These little Kalamazoo amps were produced in Kalamazoo, Michigan (of course!) in the 1970’s next to their larger Gibson siblings, and were very well built compared to other inexpensive amps of that era. All real plywood construction and baffle board; no pressed fiber board. This one gets plenty loud for practice, or small gigs. Like most solid-state amps of that era, it produces a clean tone all the way to up full volume. You will need to add a good pedal to get that tube-like distortion, like a BOSS DS-1, a Tube Screamer, or my personal analog preference a vintage DOD Overdrive.

VIDEO:

SPECS:

  • Built in 1971.
  • Somewhere between 5 and 10 solid-state watts.
  • One channel.
  • Two instrument inputs.
  • Volume, tone/on-off switch, red pilot light.
  • Black vinyl “tolex” covering.
  • Nice, vintage 10″ Alnico speaker.
  • No tremolo or reverb on this model.

COOL FACTORS:

  • Vintage, pure analog, solid-state guitar amplifier.
  • Made in Kalamazoo, Michigan – the home of Gibson at that time – where they took the art of building great guitars and amplifiers seriously.
  • Classic, made in USA, Alnico magnet speaker. Kalamazoo speakers always sounded great!
  • Not your modern mass-produced digital garbage manufactured off-shore by ???.

CONDITION:

  • I have gone thoroughly through this amp and played it for hours.
  • All wiring, components are original and in good condition.
  • Everything functions as it should, and this amp is very quiet when idling.
  • It still has the 2-prong power cord, but works just fine.
  • No major cosmetic damage.
  • Some slight separations of the tolex vinyl at some corners, but have to be up close to notice.
  • Some light surface scratches on the control panel, again, can only be seen up close.
  • There’s just a bit of looseness in the speaker fabric.

PHOTOS:

Facebook Comments

Univox UB-250 Bass Amp Video


The UB-250 is a late 60′s solid-state piggy-back (aka mini-stack) bass amp built by Univox in Westbury, New York. These were continuously made through the mid-1970′s, but this is the original design and build from 1969. Although it’s not the loudest of bass amps, it is a vintage cool analog alternative for any beginning bass student.

Sorry for the poor video and audio quality. We really need to work on improving our videos!

1960′s Vintage Ads for Kay Electric Guitars & Amps


Kay Musical Instruments of Chicago was the first company in 1962 to manufacture guitar amps that were 100% solid-state electronics. Here are some vintage advertisements from that time period.

The first ad, Transistorized Amplifiers, I found as a JPEG somewhere on the Internet years ago. Unfortunately I can’t remember where I found it, and can no longer find the source to give proper credit. If anyone knows, please give a shout. The second ad, Kay Vanguard, features the 1966 Kay Vanguard Electric Guitar and 704 Vanguard Amp, and was purchased from a seller on eBay.

Transistorized Amplifiers — An Exclusive

• Space Age Technology and Design

Published 1965. Triumph of top designers, engineers–and Kay! . . . Makes all others obsolete!

A real break-through in guitar amplification… Brought to you FIRST BY KAY. These Space Age transistorized amplifiers have so many long-hoped-for advantages, no serious musician will rest until he has one. First, they eliminate the annoying microphonics of vacuum tubes, giving you  stable, uniform true sound never affected by vibrations or voltage variations. What a boon for recording artists! Here, too, is reliable performance that eliminates tube-changing annoyance… performance that can be counted on through the most exacting engagements. And here is the most instantaneous sound with no need for warm-up or standby switch. Note, too, the new Kay easy-to-reach slant control panel and exclusive tapered cabinets. Then add to all this Space Age efficiency the further advantages of lighter weight and compact beauty of design and you’ll say Kay transistorized amplifiers deserve all the honors.

Kay Vanguard Electric Guitar and Amplifier

• Professional Sound & Style… On a Budget

Published 1966. Kay presents the most professional sound in an electric guitar and amplifier ever offered for under $200…

You can sound like the “pros” and look the part with this beautiful new Kay Vanguard Vibrato Electric Guitar and Vibrato Amplifier… And you get the exclusive “Thin-Lite” neck with adjustable truss rod for lightning fast action, vibrato tailpiece (for modern sound effects), 6 keys on one side, separate tone and volume control, adjustable rosewood bridge, inlaid position markers, shaded cherry red finish… Kay Musical Instruments— Division of Seeburg Musical Instruments, 2201 W. Arthur. Elk Grove Village, Ill. 60007.

A Briefcase Full of Blues

Kay 704A Guitar Amp with Tremolo

1965 Kay 704 Vanguard Vibrato

Find the full review here: Kay 704 Review

The Kay 704 Vanguard with Vibrato was the world’s first all transistor solid-state guitar amp, introduced by Kay Musical Instruments in 1962. Based on traditional tube amp design of that period, the vacuum tubes were replaced in the hand-wired circuits with seven germanium transistors and four diodes.

I bought this from a guy on eBay. According to the date codes found on the potentiometers, it’s a 1965 model. Completely original. A 5-watt wonder. A single front-loaded 8″ Oxford Alnico speaker. Not a whole lot of lower mid-range. But then again, no low end speaker flab either. The tone of this amp makes me think of Led Zep. Mild overdrive at full volume from my Gretsch 5120humbuckers. Fantastic OD howl from my Silvertone 1445 with its Teisco single coil pickups. The solid-state vibrato circuit is simply amazing! The vibrato effect alone was worth the price.

See more photos of the Kay 704 Vanguard Vibrato here.

Comments

tomas March 29, 2011 at 4:37 pm

glad you are enjoying it!

nice site, added it to my RSS reader….

REPLY

alex March 30, 2011 at 8:07 am

tomas, thanks for visiting the site! ~alex

glassdog March 2, 2012 at 4:27 pm

I have the same vanguard amp was wondering Its worth having someone look at it. It has some issues with the sound. It mostly crackles It was given to me by a relative. thanks

REPLY

alex March 2, 2012 at 4:59 pm

@glassdog, thanks for visiting the site. Personally, I like these amps a lot, and they are getting much harder to find. I do my own repairs to save $. I would definitely recommend having someone look at it to at least estimate the damage and repair cost. But I wouldn’t recommend spending very much to repair it. $75 to $100, max, and that’s pushing it. Unless yours is in pristine physical condition – and most are not! Good luck! ~alex

 

 

First Solid-State Guitar Amplifier

Kay Vanguard 704 Vibrato
Courtesy Mass Street Music

Lucky me! I was looking for a vintage solid-state combo amp to use at practice, and to give my trusty tube Silvertones a rest. Just scored this one off ebay today for cheap! The very first solid-state guitar amp was introduced by Kay Musical Instruments in 1962. Can’t wait for it to arrive.

 

Roger McGuinn and the Regency TR-1

Long before iPods, CD’s and Walkmans there was the transistor radio.

The advent of the transistor radio is integral to the history of rock and roll. The first transistor radio, the American-made Regency TR-1, arrived on the scene in 1954 about one year before the Sony transistor. In this video Roger McGuinn, founding member of The Byrds, tells how he received his first transistor radio and how it inspired him to become a musician. The rest of course is history, as The Byrds became one of the biggest groups of the 60′s and transformed rock music with their own style called folk-rock.

More info:

Regency TR-1 Transistor Radio History

Roger McGuinn’s Home Page

Roger McGuinn’s Transistor Radio Collection

Roger’s Transistor Radio Collection