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Our TC-503 hub adaptors fit metal NAB 1/4" audio tape reels, and will work with virtually any 10.5" reel-to-reel deck which has reel retainers built into the reel table spindles. Most consumer audio machines made after 1970 have these; the two common varieties are spring-loaded (Sony, Akai, Roberts, Pioneer, Dokorder, Tandberg; see at right) and screw-twist (Teac, Tascam, Fostex, Ampex; see below). You're likely already familiar with these if you use your machine in the vertical position with 7" reels; if not, its owner's manual explains how they work. Otari is the exception; their proprietary design is not compatible with NAB adaptors other than their own. Our TC-503 NAB adaptors fit just one Otari-labeled product family we know of; the Teac-manufactured MX-50 and its variants. Otari is still very much in business, and their clamp type hub adaptors can be obtained thru servicing dealers. Some older decks have NO integrated reel retainers, relying instead on push or snap-on rubber caps to hold reels in place. These machines were not designed for routine vertical use and cannot be used with most NAB adaptors (including ours; more on this below).
spindle hub
A) This is a typical (Teac) screw-twist spindle lock shown in the open position (unscrewed fully CCW), ready to have a 7" reel (or our NAB hub adaptor) inserted over it. Sping-loaded spindle locks look very similar when open (the upper and lower splines are aligned in the same manner), although the overall spindle length is usually shorter and the upper splines sometimes extend to the top of the spindle. 
B) This is the same spindle lock still in the open position, but now with our hub adaptor  inserted over it. For clarity, no tape reel is shown; normally it would be placed on the reel table first, and the hub then inserted over the spindle (and seated into the reel's center hole).  If shims are being used (see below), they insert between the reel tables and the reels.
locked A3300SX

C) Here is the spindle now in the closed or locked position (screwed in fully CW), with our hub adaptor secured in place. The spindle's upper and lower splines can clearly be seen to now be unaligned; spring-loaded retainers are very similar  in appearance when locked.

D) Lastly, this shows a 10.5"reel loaded and locked in place; ready to play. The Teac A-3300SX image below left shows the entire machine with both reels mounted.  Always doublecheck that screw-type retainers are tight before initiating tape movement; a reel falling off while in fast-wind becomes a dangerous projectile.
Some older 10.5" decks like the one at right lack reel retainers and therefore cannot be used with our hub adaptors (note; the other commonly available variety also does not work). Our product also does not enable mounting 10.5" reels on machines which were never intended to use them. Many consumer reel-to-reel decks accept only 7" or smaller reels. A simple test: are your reel tables under 3" in diameter, or the reel table spindles less than 10.5" apart? If yes, your machine cannot handle 10.5" reels; they physically will not fit. Second test: is the distance between either reel spindle and the nearest corner of the head block cover less than 5.5"? If yes, there is insufficient room for 10.5" reels. One final clue: virtually all 10.5" machines have a tape size selector switch (usually marked large/small, 10/7, or similarly) used to adjust fast-wind speed and torque. If your deck lacks this feature, it likely accepts 7" or smaller reels only. Note that failing to set this switch properly can cause severe tape stretching and tape spillage or breakage when transitioning from fast forward or rewind to stop; don't ignore it!
2300

Above is a Teac A-3300SX with 10.5" reels mounted using our hubs. Note the location of the reel tables way out overhanging the upper corners of the front panel; this is typical of most 10.5" machines and is necessary to provide clearance for the reels. The size selector switch is right next to the speed selector, under the left reel. This switch adjusts fast wind speed, torque and braking balance to match the different reel diameters.

 Above is a Teac A-2300SX; this 7" model's reel tables are more centered, making for a much shorter machine. The 7" reels barely clear the head block; there simply is no room for larger reels. Note also only two switches are present under the left reel (compared to the A-3300SX's three); this deck does not need or have a tape size selector switch.
          
Metal NAB reels are quite a bit thinner than plastic ones, and sometimes require spacer shims. These when placed between the reel table and reel, raise the reel height slightly so as to properly align the tape path and prevent the tape rubbing against the edge of the reel. On Tandbergs and older Akais as well as some Revoxes and Studers, the spindle lock doesn't tighten up enough to hold metal tape reels snugly against the reel table unless shims are used. This looseness can cause the reel to move and rattle against the hub when fast-winding. Placing a shim between the reel table and the metal reel increases the overall reel thickness, and dramatically improves the clamping force so that the reel will not shift within the hub adaptor. We do not supply shims with our hubs or separately. Shown above is a pair of Otari-manufactured rubber shims; virtually every reel machine maker had a version of these, but only Tascam and Otari still sell them. Fortunately, you can easily make your own; see at right.
We've recently discovered a great way to create shims by utilizing round paper or cork disposable drink coasters. Party goods stores sell these, and so do some package stores (usually printed with beer logos). Bars and restaurants use these and throw them away after one use; simply take yours home with you. Coasters right around 1mm thick and 3.5" to 4" in diameter work great. Find and mark the center point; then punch a hole with an awl or icepick. Carefully enlarge the hole to about 15mm diameter using a ream, scissors blade or other pointy  implement until it just fits snugly down over your reel table spindle and flush against the reel table. Neaten up the hole edge and you're done. The hole may fray and enlarge with time if removed and remounted routinely (unneeded unless you switch reel sizes a lot) but given that these are virtually free and quick to make, this aging issue does not pose a significant downside.

Why choose our hub adaptors? Ours are exact copies of hubs Teac/Tascam supplied with their decks; compare the Teac hub on the left to ours on the right. Sony, Pioneer, Tandberg, Technics, Dok and and others all supplied similar ones. Our TC-503s are practically indestructable. The only other variety commonly available today (Tascam TZ-612) has moving parts which rub and wear, and may fall apart with age or if overtightened. And the BEST reason: ours are less than half the price and cost less to ship...

BIN NAB 10.5" Reel Hub Adaptors;
$24.50 a pair!!!

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