From Wollensak Recorder History and Guide 
by: stenkbomm

I suppose it might be helpful to write a Wollensak recorder guide while my memory still retains some details. I was a Wollensak Factory Authorized & Trained service facility manager and technician until their end.

Wollensak started out as a lens manufacturer over 100 years ago. They provided lenses and lens components to all the major American manufacturers during the 20th century until the Japanese took over the market. They also made some shutters and formed a partnership with The Revere Camera Company that led to them offering some cameras (mostly 8MM) under their name in the 50s and early 60s.

That partnership with Revere would have profound implications for both companies when Revere, like many other optical companies (Ampro, TDC, Bell & Howell, etc.) of the day (Early 50s) started venturing into making tape recorders. Revere's first offerings were mundane but they came up with a design that was a winner and would remain the basis for their machines for decades.

Enter Wollensak. They took the basic mechanism, designed a modern "aircraft construction" shell to house it, a simple 3-key and slider control system, and a compact amplifier. The resulting unit was small, light, stylish, and an instant hit. The "1500 series" was born.

Over the next few years Wollensak/Revere would make refinements and optional versions of it.

The original T-1500 was a half-track (2-track mono) recorder with a unique (for the time) amplifier, using an interstage transformer instead of a phase inverter to drive its push-pull 12AB5 amplifier. It had Record, Play, and Public Address capability which made it a hit with lecturers, schools, etc. The amplifier is often seen on eBay being sold as a "guitar amp" or other non-tape recorder usage.

3M acquired Revere/Wollensak as a perfect companion to its tape manufacturing business. The division eventually became known as the "Mincom Division" with its headquarters in St. Paul, MN. The new parentage allowed research and innovation.

Variations of the 1500 quickly appeared. One of the first was the T-1515, a Stereo version. The 1515 replaced the standard mono head with a stereo head and added a small preamplifier for the second channel. By plugging the unit into a stereo system or adding a satellite speaker/amplifier the then-new Stereo tapes could be played. Recording was still only mono, however.

This was quickly followed by the T-1515-4 as the industry went to 4-track tapes. The head system was redesigned to include the new head and to provide a selector that moved the head up and down. The 4-track setting allowed for playing prerecorded 4-track stereo tapes. There was also a 2-track setting that lowered the head slightly so it tracked 2-track tapes without the loss in channel one that was common to other brands. A 3rd position allowed for recording 4-track mono by shifting the active (recording) poles to the different parts of the tape to accomplish this. Others would adopt this approach too, including Webcor & Akai/Roberts.

One of the rarest was the TS-1520/T-1700, which could run from standard AC or from a 12 volt DC (car) battery thanks to their built-in vibrator or inverter systems. (This unit should not be confused with the later 1520AV) This allowed location recording of a better quality than the average existing transistor and clockwork units then available but improvements in these designs made it obsolete very quickly.

Small internal improvements were made, mostly to the idler wheel carriers and later to the rewind arm but the drive mechanism was essentially still the original Revere design.

There was also an "economy" series of the two then-current 1500 models (T-1500 & T-1515-4): the "1400 series". The T-1400 and T-1440 were identical to the 1500 units except they were painted a dark gray instead of having the brushed or polished bare aluminum of the regular units.

For the "deluxe" end of the market they redesigned the shell and added push buttons and relays to make soft-touch controls and the possibility of remote operation available. The T-1600 & T-1616 were never great sellers but did look spiffy and added prestige.

The demand for mono recorders was falling, however, and what there was for it was increasingly being filled by cheaper units from Japan. Wollensak needed a stereo RECORDER to compete.

The engineers took the base mechanism and redesigned it to incorporate power-assisted operation and a new 2-channel amplifier. The case got a totally new look and side-mounted speakers. The T-1580 was an instant success and had fairly good specs for the price. Ads with name musicians appeared in several publications. It retained all the traditional features, including PA ability. A mono version, the T-1570 never caught on, but the 1580 remained in the catalog for a few years.

The 1580 was expanded into a large upright unit seemingly inspired by the popular Roberts (Akai) units of the day. The T-1980 "Sound Room" was mechanically and electronically mostly identical to the 1580 but bigger and more impressive, with meters instead of the neon indicators used until then.

The 1980 was also offered as a build-in version without the carry case as the T-1780.

The 1580 mechanism was also used, with different amplifiers, cases, in lower-priced or later models such as the T-1280.

In an effort to keep a foot in the low-end market a totally new design, the T-524 was offered but never did well.

During all this the original 1500 was still selling well, especially to schools and corporations. 3M renamed it the T-1500AV but otherwise it remained pretty much the same until they decided to update it to a transistor (solid-state) amplifier and give it a small meter. It was then dubbed the T-1500SS.

Price had become a big issue for the consumer lines and production costs on the old 1500 mechanism and case had gone up, so a new series was designed for the consumer market - the 5000 series.

The new designs were compact and rectangular. A reel on each side with a small control console between them. They could sit on bookshelves or be hung on a wall. A simple mechanism, plastic parts, and power-operated push button controls made for a lighter unit. All were solid-state. Models ranged from full portables with plastic cases to wooden-cased models with detachable wing or shelf speakers. With the exception of one mono model all were stereo. The first series was the 5200/5300 series (5150 for the mono version) and a later series with mechanical improvements and a headphone jack was the 5700/5800 series.

T-1500 - the original Revere-based design introduced in 1956. Offered for 10 years with various cosmetic changes/refinements.

T-1500AV - "Industrial" version of original (1965)

T-1500SS - The solid state update of the original design. (1967)

T-1515 - The 1958 "stereo" offering.

T-1515-4 - The late 1959 update of the T-1515

T-1520/TS-1520 - AC/12 Volt car model. (1960-2)

T-1520AV - The updated (final) AV model. Adds Auto Level Recording (ALR) (1969-81)

T-1570 - Mono version of T-1580 (1962)

T-1580 - First Stereo recorder. (1962-6)