eBay

NUMARK TC4100 MIXER

Tone Calibrator

IMPORTANT NOTE: I personally wrote every word in this listing. These words, other than a few minor edits over time, have been in this listing for two or three years. When you read it you might reasonably concluded that I know what I'm talking about regarding the TC4100. That would be correct.

If you look around at other TC4100 listings you will see large pieces of my verbiage making up the majority of the verbiage in the listings of other sellers who have STOLEN my work. And thus, they also may sound like they know what they're talking about. That may or may not be correct.

I've requested that these thieves remove MY VERBIAGE from their listings. Some have honored that request and some have ignored it.

NOTE: This listing includes my $49 repair kit (new pots) that you're going to need regardless of where you buy your TC4100 or what you pay for it. Read on.

If you’re in the market for a device to switch audio inputs and outputs for up to four tape decks, VCR's, CD/DVD players or recorders, your PC sound card, or any other two channel audio player or recorder, you should have this device on your short list. And if you don’t know what a Numark TC4100 is you should read this listing in its entirety. Once you understand the capabilities and features of this difficult to find component you will be hard pressed to convince yourself that some other (lesser) switching unit is a better fit for your needs.

Read on for some information you’ll be happy to have, lest you discover later that the simple minded tape switching unit you settled for can’t measure up to the TC4100.

You'll find listed here very convenient features that don't exist in other switching units. Go look at the DBX-200X, DBX-400, Vanco TDS-3, SONY SB-300, the AKAI DS-5 or most any other tape deck switching unit out there for comparison. See if ANY of them include ANY of the following features of the NUMARK TC4100:

· Two VU meters

· Internal tone generator

· Signal level adjustment for the individual decks

· Complete input and output switching for each tape deck

· Rear panel inputs & outputs for up to four stereo tape decks

The Numark is the only unit noted above that offers ANY of these significant features, and the Numark offers ALL of them!

There is one shortcoming with this model that I thoroughly addressed below.

A little history first-->> I bought my first Numark TC 4100 in 1984. I bought it from DAK and as far as I know Drew Kaplan (DAK) is the only retailer to offer this item. See his advertisement from a 1985 Stereo Review). I still have this Numark mixer, and I still use it (after repairs). In 1984 I had two reel to reel tape decks, a cassette deck, and a stereo receiver that had just one tape monitor circuit. The TC 4100 did all of the switching I needed, with inputs and outputs to spare, and considering the built in VU meters and tone generator, added much more function and value than any of the simple minded tape switching units that were available at the time. That is still the case today!

After many years of use one of the channels on one of the inputs quit working. Later a channel on another input quit. And then another. After enough of that I bought a second TC 4100 right here on eBay. And guess what. It exhibited the same sort of failure...losing one or both channels from one or more of the four inputs, rendering those inputs unusable!

So I bought another...and another. And most of them had the very same problem to varying degrees. I was able to salvage parts from one of them to repair another to get one mixer that was 100% operational. But keep in mind here that I was replacing an old part with another old part.

Over time my needs changed and the number of TC 4100's I had on hand grew. I now have two of them in use in my vintage Quad system, another one in use in the Quad system in my office, and another two in use in the test bed in my shop where I repair Teac tape decks. (See photos.) And another dozen or so of them on hand!

What I've learned is that the level controls (the potentiometers (pots) behind the sliders on the face plate) in this machine regularly fail. I believe this is a result of age more than use as I've seen virtually new vintage examples of this mixer failing as described. Depending on which pot failed the result will be input or output paths that no longer work, a meter that no longer works, or a tone generator that appears to no longer work.

We are now 35+ years down line from the initial availability of this mixer. Based on decades of experience with manyTC4100's I'm confident in saying that eventually all of them are going to have issues with these potentiometers. If you doubt this take a look at another of my listings where I offer just the repair kit (pots and lamps) for this mixer. You'll see that I've sold several dozen repair kits through that listing. TC4100 owners are buying the kit because their TC4100 is failing in the manner described above!

Most of the other two channel mixers & switchers that are available out there are also 30+ years old, each with its own shortcomings. The seller may or may not identify those issues, but nothing lasts forever.

Through a lot of research, trial and error, I eventually tracked down a suitable substitute part for the pots, compatible both electrically and physically with the originals. Having bought dozens of these mixers, and a couple hundred pots as replacement parts, I find that I've actually repaired just six of them for my own use. I intend to sell several of my spare TC4100’s, along with the repair parts that I know will be needed. If you can use a screwdriver, needle nose pliers, and are adequately skilled with a soldering iron, or if you know someone who is, this is a repair that can be finished on your kitchen table in an evening. The pots are soldered onto a printed circuit board, so a steady hand is necessary.

I'll include a copy of a four page installation document that came with my original unit from Numark. (Interestingly, this document specifically warns against using "SPRAY CLEANER FOR ANY SLIDE CONTROL". This is precisely what someone would try when the failure I describe here exhibits itself.) I'll also include some pointers to help with the eventual replacement of the pots...things that I learned when I replaced them that I'm happy to pass on.

The unit you get MAY work fine upon arrival but don’t expect that! Anyone selling a similar item and claiming that it works perfectly MAY be offering the very rare one that does currently work perfectly. I'll point out here that to completely test this mixer requires four stereo input/output devices (for example, tape decks). Personally I have over 20 tape decks. Having bought a few dozen TC4100's, I can say that the only one that consistently worked PERFECTLY for years is the one I bought new back in 1984. And I’ve purchased several that were claimed to “work perfectly” but failed as described in this listing IMMEDIATELY upon arrival. Caveat Emptor!

SO, WHAT I’M SELLING HERE IS ONE NUMARK TC4100 AND SIX REPLACEMENT POTS TO BE INSTALLED BY THE BUYER (or his/her technician depending on the buyers soldering skills). The unit will be complete, both meters will work and are backlit. Some of the inputs will operate upon arrival. Expect maybe a few scratches on the sides, top or bottom, but the faceplate will be cosmetically presentable.

Stated shipping is for the lower 48 states and includes insurance and packing material. Any international sales will be shipped via the eBay Global Shipping Program. The photos are representative of what I have on hand and WILL NOT be the exact machine you receive. I won't sell you a machine that looks like a train wreck.

Please take a look at my feedback and note that a half dozen or so buyers of my repair kit have all provided positive feedback. I normally offer returns but in this case I'm asking the buyer, or his tech, to open up the unit, and do some soldering. I can't take the chance that a buyer overestimates his soldering skills, burns up a few land patterns on the printed circuit board, and then wants to return the unit. It happens!

This item is being offered as-is with the potential issues noted. While I'm listing it as not returnable if the buyer discovers something that I haven't mentioned here please contact me. I'm a reasonable man and would think that we can work something out that everyone can live with.

Thanks for looking!