Shure SLX vs SLX-D: Analogue Legacy Against Current Digital

In this guide:The short answer · The differences · If you own SLX · Against the alternatives · Picks · FAQ

People searching for SLX are usually in one of two situations: they own an older system and want to know whether to keep it, or they have seen SLX and SLX-D listed side by side somewhere and assumed they are variants of one product.

They are not. SLX is the older analogue range, discontinued. SLX-D is the current digital range, and the two share a name and very little else.

The short answer

If you are buying, buy SLX-D. It is the current product, it is digital, and it is what is supported.

If you own SLX and it works, it will keep working until the band it uses changes or a part fails. It is not dangerous or obsolete overnight, but it is a system with no development behind it, and spares get harder every year.

What actually separates them

The audible difference is the companding. An analogue radio link cannot carry the full dynamic range of a microphone, so it compresses on the way in and expands on the way out. Done well it is subtle, and on a busy stage most people will not pick it out. Done at the edge of range, or on a quiet solo passage, it is the slightly pumping, slightly veiled quality that digital systems removed.

What to do if you already own SLX

Nothing urgent, in most cases. Work through this.

• Check the frequency band your units use is still legal for you. UK spectrum has changed more than once, and equipment tuned to a retired band cannot legally be used regardless of condition.
• Keep it if it works and the channel count is small. A working two-channel system in a school hall owes you nothing.
• Do not build on it. Adding channels to a discontinued analogue system in a crowded band is spending money on a dead end.
• Plan the replacement around the capsules. Your SM58 and Beta 58A heads carry over to SLX-D bodies, so the microphone investment is not lost. See capsule compatibility.

SLX-D against the rest of the range

SLX-D sits in the middle of Shure’s line. Below it, BLX is the entry system, simpler and cheaper, aimed at fixed installs and small bands. Above it, QLXD and ULXD add networking, more channels and more robust RF for larger systems.

The two comparisons most people actually need are BLX vs SLX-D, which is the entry decision, and EW-D vs SLX-D, which is the cross-brand one.

Frequently asked questions

Is SLX still made?

No. SLX is discontinued and has been replaced by the digital SLX-D. Remaining stock turns up used, but there is no current production or development.

Can I mix SLX and SLX-D?

The transmitters and receivers do not talk to each other across the two generations, so no. They can share a rack and a frequency plan, and you can run both systems in the same venue, but each transmitter must be paired with a receiver of its own generation.

Do my SLX capsules fit SLX-D?

Shure’s RPW replacement heads thread onto both generations of handheld body, so an SM58 or Beta 58A head carries over. That makes replacing the radio cheaper than replacing the whole system.

Is analogue wireless worse?

Not automatically, but it is limited. Companding is the compromise analogue makes to fit audio into the radio link, and digital removes it. On a small stage in a quiet band you may not hear it. On a quiet, exposed source you will.