Beyerdynamic's Tesla driver technology has evolved into its second (2.0) iteration, which now upgrades the classic DT 770 into the new DT 1770 Pro.
So what's changed? First off, the price; you can buy nearly three pairs of DT 770s for one pair of DT 1770s. The rest is performance, from frequency/dynamic response to power handling and distortion.
The single-sided cable is detachable (at last!) with the package including coiled and straight types. The carry case houses a set of leatherette earpads in addition to the fitted velour pair. The big comfy circumaural design hasn't changed much, and though they are on the heavy side they are well supported enough to allow lengthy immersion.
The Tesla 2.0 driver info talks about a triple layer diaphragm, high precision meshes and acoustic fleeces, etc. All very clever, but what does it mean in practice? At first they appear similar to their predecessor, but with one (negative) aspect refined away: the 10kHz over-brightness. With the DT 1770s Beyerdynamic has smoothed over this region with a velvet rolling pin to create a beautifully balanced, peak-free high-end (our ears say 'thanks').
There is still the full bass extension one expects from DT 770s, but with more punch (faster dynamic response), more headroom (less distortion) and a sense that the earcup can accommodate more bass (the earcup is in fact substantially deeper than the 770s).
We often use the 770s as a bass checker, so if they're woofing and the bass masks the low mids we're in the low frequency badlands, but the DT 1770s respond almost too well and could lead to overcooking for the bass addicted. As with all monitoring this is something that requires familiarity and, whatever your previous experience, clear and unfettered audio replication is key to high-quality work. Mixing the low-end on DT 1770s is a pleasure, and efficient too.
The DT 1770s are exceedingly well balanced across the audible spectrum. The mid range is free from audible phase shift, allowing the clarity essential for professional use. The sound stage projected into your head is as pleasurable as it is revealing.
They provide a highly detailed view into your audio, from left to right, front to back, and even into the corners! From discrete reverb tails tucked behind a busy mid range, to tiny distortions and clips, they reproduce whatever your signal chain is capable of supplying. Audio restoration, mixing and tracking all greatly benefit from the quality the DT 1770s offer.
If the money was there we'd snap these up without a second thought. Not only are they top quality, but being Beyerdynamic they are supported with a full range of spares. That said, these are very well made and will provide years of service before anything needs replacing.