Sonicraft A2DX Lab: Ampex 440C Tech Notes

AMPEX 440C

Ultimate Professional Small-Format Multitrack A2D Transfers

Half-inch 8-track, 4-track, 3-track and 2-track tapes as well as quarter-inch 4-track, 2-track European DIN stereo and full-track mono, can all be transferred into the digital domain with ultimate quality on our thoroughly customized Ampex 440Cs.

Basically a subset of the Ampex MM1200, these machines provided the platform used to prototype the A2DX Ampex M1200 improvements. The machine on the right was the first machine to undergo the A2DX restoration and enhancement process.

Many modifications have been made: 1/4" 2-track, 1/2" 3-track, and 1/2" 4-track all utilize the same style Flux Magnetics ME playback heads as found in the A2DX Ampex MM1200 large-format multitrack machines. And, our 1/2" 8-track configuration features a custom made PLX playback head from JRF Magnetics. We've also added numerous other modifications to heads and electronics to upgrade the signal path of our Ampex 440Cs.

Extensive listening tests have proven these machines to be amazingly accurate as well as "pleasantly transparent".

Upgrading the Transports -- Gentler Tape Handling and Superior Tape Tracking

We've made four modifications to our 440C transports to make them gentler on older tapes and improve tape guidance so that tapes will be will track 100% accurately and consistently over the heads.

Ampex 440Cs fully rebuilt with Flux heads, RTZ record and repro amps,fixed precision guides, variable FF/RW shuttle and constant tension mods

The first modificaton was to add constant tension capability ensuring gentle and consistent tension during tape play.

The second was to modify the transports for variable speed shuttling in fast wind mode. Fast forwarding, rewinding and shuttling older challenged tapes can put too much stress on them. This modification allows us to dial in the correct tension during tape shuttling. It makes the transports gentle enough to handle even extremely fragile tapes.

The combination of constant tension play and variable speed shuttling makes quantum improvment to the gentleness of these transports.

The third modification was to optimize the transport for a single tape width. The 440 transport was designed to run both 1/4" and 1/2" tape. Running both tape widths requires compromising tension settings so that neither format runs optimally.

Dedicating each of these 440Cs to one tape width allows us to optimize the transport tensions. The 8-channel machine is optimized for 1/2" tape (two, three, four and eight track reproduction) while the four channel machine is optimized for 1/4" tape (mono, two and four track reproduction).

The fourth modification was to add additional tape guidance to the tape path. To facilitate switching between tape widths, Ampex equipped the 440 transport with switchable tape guides. But these guide tape poorly because they are combined with moving parts that are not stable. To solve this problem, we have added rigidly mounted precision guides from an Ampex ATR100 to the supply and takeup tape paths and replaced the stock 440 tape guides with steel posts.

These two modifications give us optimal tape pack and contribute to rock solid tape travel over the heads.

The New Tape Path

440C Transport Mod Up Close

Here, we see the 1/4" deck where we have mounted a pair of ATR100 1/4" precision tape guides to the deck on machined mounts designed to make the guides hold the tape at the precise height of the deck's heads.

We've also replaced the stock guides with steel posts which now simply rest on the tape. The tape tensioning and tape break safety functionality are maintained but the guidance of the tape is now completely handled by the precision rolling guides and the three-point tape guidance system in the head assembly.

We have seen a marked improvement in the tape pack and the stability with which the tape sits across the heads while in motion. There is simply no sign of tape wandering (the "country lane" effect) regardless of the brand or vintage of tape being played.

The Left Guide

Left 440C Guide and Tension Post Up Close

The Right Guide

Right 440C Guide and Tape Break Arm Up Close

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