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NAB Hubs Help Page 

Our TC-503 NAB adaptors will work with both plastic and metal reels, and fit most any 10.5" machine 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, Pioneer and others) and screw-twist (Teac, Tascam, Fostex, Ampex and others). You're likely already familiar with these if you use the machine in the vertical position with 7" reels; if not, your machine's owner's manual should explain how to use them. One manufacturer who never switched to built-in reel retainers is Otari; their proprietary design is not compatible with NAB adaptors other than their own. Our NAB adaptors fit only one Otari-labeled product family we know of; the Teac-manufactured MX-50 and its variants. Otari is still in business and their clamp type hub adaptors can be obtained thru their dealers.
Akai spring type spindle
Akai spring-loaded
spindle lock;
click image to enlarge
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. Click on the image to enlarge. 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). Click on the image to enlarge.
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. Click on the image to enlarge. 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. 
NAB hub adaptors do NOT allow the use of 10.5" reels on machines which were simply not designed to use them. The vast majority of consumer reel-to-reel decks sold accepted only seven inch or smaller reels. A simple test: are your reel tables less than three inches in diameter, or the reel table spindles less than 10.5" apart? If yes, your machine cannot handle 10.5" reels, because they physically do not fit. Another test: is the distance between the reel spindles and the nearest fixed object (on either Teac shown below, this would be the upper corners of the head block cover) less than 5.5"? If yes, there is insufficient clearance 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 machine lacks this feature, it likely accepts seven inch or smaller reels only. Note that neglecting 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!
3300 2300
Above is a Teac A-3300SX with 10.5" reels mounted using our hubs. Note the location of the reel tables way out in the far 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 shown 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); no tape size selector switch is necessary or provided.
shim           coaster shim
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 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 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 move within the hub adaptor. We do not supply shims with our hubs or separately. At left above is shown a Tascam-manufactured rubber shim, but you can easily make your own. UPDATE; We've recently discovered an even easier way to create shims than those methods suggested previously; round paper disposable drink coasters (see example at right above). Party goods stores sell these, and so do many 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 with a ream or the tapered end of a scissors blade until it just fits snugly down over your reel table spindle and flush against the reel table. Clean up the hole edge and you're done. The hole may fray and enlarge with time if removed and remounted routinely (something you do not need to do 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. Very old reel-to-reels which use push-on or snap-on rubber reel holders such as the Sony ones shown above will not work with our NAB adaptors (and be advised; the much more expensive  TZ-612 Tascam/Teac variety sold elsewhere will not work either).  These machines  were originally designed to be operated lying on their backs, before vertical operation became the norm. Teac's type TZ-610 hub was intended to fit such machines; this product was discontinued over twenty years ago, and sadly we know of no source for anything similar. If you are successfully using rubber push-on reel holders with 7" reels, do NOT count on them to secure a much heavier 10.5" reel. A metal reel which falls off the machine while in rewind or fast forward becomes a VERY dangerous flying object. Use our hubs only on machines that actively secure the tape reels with twist type spring loaded or screw type retainers as described above. Older machines with weak reel spring type clamps (see commentary re this at left) are often easily repaired by stretching the original tensioning springs to re-energize them, or by replacing the springs with stronger ones.

Why choose our hub adaptors? Ours are practically indestructable; the TZ-612 variety has moving parts which rub and wear, and can fall apart with age or if overtightened. We always have ours in stock and we control their manufacture; sellers of those other hubs mostly obtain them as they sell them, do not control their supply and cannot guarantee long term availability. And the BEST reason: ours are less than half the price, and generally cost less to ship...
$24.50 per pair plus shipping

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