ESB Audio 1.6K2X — 1000 Series 2-Way Speaker System with 12dB Crossover

ESB Audio 1.6K2X — 1000 Series 2-Way Speaker System with 12dB Crossover

The 1.6K2X is a complete two-way component system from ESB's 1000 Series: a 6.5"/165 mm paper cone woofer on a Y-25 ferrite motor, a 1"/25 mm silk dome tweeter on N-35 neodymium, and a 12 dB/octave passive crossover. 4 ohms, 90 W continuous and 180 W peak, covering 50 Hz to 21 kHz at 89 dB. Sold as a pair.

Everything the front stage needs is in the box, driven from one amplifier channel per side.

Read the Power Rating Carefully

ESB qualifies the 90 W and 180 W figures explicitly: they apply behind an 80 Hz high-pass at 12 dB/octave.

That is an installation instruction rather than a footnote. Run the woofer full-range and low frequencies it was never intended to reproduce will consume its excursion, at which point the rating no longer describes anything. Set the high-pass and the driver takes what it is rated for.

Most factory head units apply no high-pass. If nothing in the system provides one, that is worth resolving before deciding how hard this set can be driven.

Separate Tweeter, and What It Buys

The tweeter is a 25 mm silk dome with a 25.4 mm voice coil on an N-35 neodymium motor, mounted independently of the woofer.

Two things follow. The larger dome and separate mounting take the system to 21 kHz at 89 dB — a decibel more sensitive than the 1.6C coaxial and slightly further extended, because the tweeter is not constrained to sit on the woofer's axis and can be optimized on its own terms.

More importantly, it can be placed. A tweeter in an A-pillar, sail panel, or door upper produces the top end from near ear height rather than from down in the door — which raises the apparent height of the whole stage. That is the single largest difference between a component set and a coaxial, and it is an installation benefit rather than a specification one.

The trade is that the two drivers now sit at different distances from the listener, and a passive crossover cannot correct for that. Mounting them reasonably close together keeps the difference small.

The Woofer

A paper cone at 14.1 grams of moving mass on a Y-25 ferrite motor with a 25.5 mm voice coil, resonating at 64 Hz with a Qts of 0.87 and 11.5 litres of Vas.

Paper remains in use at every price level because it has a good stiffness-to-weight ratio and self-damps — internal losses in the fibre absorb resonances rather than storing and releasing them.

The Qts of 0.87 is the number that matters for where this driver goes. A lightly damped driver does not need an enclosure to control it, which is exactly right for a car door — a large, leaky volume that provides almost no acoustic loading. A low-Qts driver in the same door would sound thin. This one was designed for the door it will actually be installed in.

The 12 dB/Octave Crossover

A second-order network on both sections, included in the box and matched to these two drivers.

Twelve decibels per octave is the standard choice for a passive two-way and it is the right one here: steep enough to keep low frequencies away from a 25 mm dome, gentle enough not to require the component count and insertion loss of a steeper network. The drivers were specified together with it.

System Application

A front stage running from one amplifier channel per side — a modest two-channel amplifier, or two channels of a four-channel with the remainder on a subwoofer.

It is the right choice where the vehicle offers a tweeter location. Where it does not, the 1.6C coaxial puts the same 1000 Series approach into a single opening.

Pair with the 1.10SD2 or 1.10SD4 below it. The 80 Hz high-pass this set is rated behind is exactly where a subwoofer should take over, and the two products are specified to meet there.

Installation Considerations

Check depth before cutting. The woofer is 165 mm across the flange with a 144 mm mounting diameter and roughly 59 mm of depth.

Set an 80 Hz high-pass at 12 dB/octave ahead of the crossover. The power rating depends on it.

Seal the woofer to the door. A high-Qts driver is relying on the door to behave as a rough enclosure, and an unsealed mounting lets rear output wrap around and cancel the front — which costs exactly the bass this driver was built to produce.

Keep the tweeter and woofer reasonably close, and at similar height where the vehicle allows. There is no delay available in a passive system to reconcile a large separation.

Observe polarity on both drivers. A reversed tweeter in a 12 dB/octave network produces a cancellation at the crossover point that sounds like a tuning problem and is not one.

Specifications

• Type: 2-way component system with passive crossover
• Woofer: 6.5" / 165 mm paper cone, Y-25 ferrite magnet, 25.5 mm voice coil, Re 3.3Ω
• Tweeter: 1" / 25 mm silk dome, N-35 neodymium, 25.4 mm voice coil, Re 2.8Ω
• Crossover: 12 dB/octave passive, included
• Nominal impedance: 4Ω
• Power handling: 90W continuous · 180W peak (behind an 80Hz 12dB/oct high-pass)
• Frequency response: 50 Hz – 21 kHz
• Sensitivity: 89.0 dB @ 1W/1m · 92.0 dB @ 2.83V/1m
• Free air resonance (Fs): 64 Hz
• Qes 1.10 · Qms 4.21 · Qts 0.87
• Vas: 11.5 litres · Mms: 14.1 g · Cms: 0.44 m/N
• Woofer outer diameter: 165 mm · Mounting diameter: 144 mm · Depth: approx. 59 mm
• Sold as: pair

HF Audio Perspective

The useful comparison here is not against more expensive ESB systems. It is against the coaxial that costs slightly less, because that is the decision most buyers are actually making.

On paper the difference is modest: a decibel of sensitivity, a kilohertz of extension, a 25 mm dome instead of 20 mm. In the vehicle the difference is larger than those numbers suggest, and it comes from mounting. Getting the tweeter out of the door and up near ear height raises where the music appears to come from, and no specification captures that.

The condition is that the car has somewhere to put it. If the answer is a tweeter stuck to a door card with tape because there was nowhere else, the coaxial was the better purchase and the money is better spent on door treatment.

What we would emphasize on any 1000 Series install: this driver's Qts of 0.87 means it was designed to work in an ordinary car door, and it will. Set the 80 Hz high-pass, seal the mounting, and give it a subwoofer underneath. Those three things matter more to the result than anything else available at this price.