Kudos Sigao Drive passive/active crossover
Every now and again, a product turns up for perusal that defies easy description and the Kudos Sigao Drive might be the gold standard of the breed. Kudos is a County Durham based speaker manufacturer and a significant proportion of their products are supplied with both conventional speaker terminals and a row of inputs that connect directly to the drivers. These bypass the internal crossover in order to make use of an external, active one. Options, from Linn, Exposure and Naim are available to use these connections but Kudos has decided to create an in-house alternative that allows you to use certain of their speaker ranges (Titan and Cardea) with the amplifiers of your choice.
Where this notionally logical process takes a sideways lurch is that the Sigao Drive is unlike any of the other third party solutions. It is entirely unpowered and isn’t an active crossover in the traditional sense of the word but it’s not a passive external crossover in the manner of a Living Voice – perhaps the best known practitioners of the art – either. It is still placed ahead of the amplification, taking a signal from a preamp and passing it on to an amplifier responsible for each driver or pair of drivers but it does this while receiving no power of its own.
As you might imagine, this is not the work of a moment to achieve. Kudos has worked with Roy George; longstanding Naim engineering director to create a device that functions in the manner of an active crossover but less mains power. Key to achieving this is the use of three unique, high quality inductors per channel and a custom-isolated PCB intended to minimise microphonics. This assembly is placed in a machined from solid aluminium case that is extremely sturdy in its own right.
As a function of its ability to work with any speaker in the range and also allow pretty much free reign in terms of amplifier choice, each Sigao Drive leaves the factory as a blank slate. Using a carefully calculated configuration of resistors in the crossover’s outputs, each unit has the ability to work with any Kudos speaker and with a very wide selection of amplifiers. To configure it to each application, Kudos will supply your unit with both loudspeaker loading and amplifier matching plugs, both of which have a DIN connection.
The loudspeaker loading plugs are relatively self explanatory. They provide the specific increments for each Kudos speaker in the range and there will be either one, two or three of them depending on the driver configuration of the speaker in question. The amplifier matching plugs ensure that the Sigao Drive presents the correct impedance to the amplifiers being used; something that is important when no electrical power is present in the unit itself. Kudos has amassed the required information for a wide selection of amplifiers and states they should be able to secure the required information to allow most designs to work with the Sigao Drive.
Once the DIN connections have the relevant load and matching plugs in place, the Sigao Drive can then be connected to a preamp and power amplifiers via marked inputs and outputs. This can only be done over RCA connections; Kudos does not believe that balanced connections impart any advantage in this situation. The process of getting a Sigao Drive in and running is something that makes much more sense when you can physically see the unit and the connections to hand. As with any device where inattentive wiring could risk sending bass frequencies to a tweeter (an action Kudos has assured me is less likely to result in a driver in orbit than you might think), it’s best to take your time and work logically. With everything in place, the Sigao Drive, is compact, beautifully finished and entirely unobtrusive.
The catch, such as it is, is that for the lower rungs of the Kudos speaker ladder, the Sigao Drive is a significant cost. Judged against the £9,700 cost of the Titan 505, the £6,500 price tag of the Sigao plus the need for at least one more power amp (assuming you already have a pre and power amp combination; if you don’t, those costs keep coming) are very significant. Owners of the larger speakers will find these costs somewhat lower as a proportion of their total system but I’d hesitate to describe the result as cheap in any case.
System and sound
I’ve been living with and using a pair of Kudos Titan 505 standmounts for a number of years. I’ve used them with a variety of amplifiers via their internal crossover and have also tested this pair with Exposure’s VXN active crossover and electronics so I have a reasonable handle on their performance in differing states. I made use of a pair of Chord Electronics TToby power amplifiers to drive the speakers and used both a matching Hugo TT2 and a T+A PSD 3100 HV streaming DAC as preamps.
The single most important thing that the Sigao Drive does, practically from the outset, harks straight back to how the 505 sounded when it was running with the Exposure active gear. At no stage during normal passively connected listening does the 505 sound congested or confused. This is why the jump in performance from going active is such a jolt; you don’t imagine anything getting better before it suddenly and emphatically does. The opening Remind Me on Emily King’s Scenery suddenly has a space and airiness to it that you simply don’t experience in the same way, even via very talented amplifiers. King is a physical presence between the speakers, beautifully defined against the electronic backing but never divorced from it.
And when the wonderful rolling synth bassline kicks in, the advantages of allocating a complete amplifier to handling the 505’s isobaric bass drivers becomes readily apparent. The Sigao Drive doesn’t extract ‘more’ bass from the 505 but it unquestionably secures better bass. It starts and stops faster and reveals more detail from low notes than the internal crossover is able to do. The spruce up of everything under 200Hz is unequivocal and takes a speaker I already consider remarkably talented for a relatively compact standmount to a level that very little else of a similar size can handle.
Something else that became apparent when I switched from the TT2 as a preamp to the large and extraordinarily sophisticated T+A is that the Sigao seems able to unlock performance without putting very much of itself into the performance while it does so. The T+A’s darker and more potent presentation is effortlessly integrated in the sonic portrayal in a way you can easily perceive if you connect conventionally, but the Sigao brings an order and cohesion additional to what the T+A possesses on its own.
What is no less important is that the Sigao Drive has no effect on two absolutely key attributes of the 505. The first is that despite the extra space and resolution on offer, this speaker is still impressively forgiving of less than perfect material. A very spirited run through Ritual by White Lies; an album that I enjoy very much but that has the dynamic range of a Dictaphone cassette, sees the Sigao Drive prise open a little space amidst the congestion but refrain from making the whole result unlistenable.
It’s also maintains the plain and simple joy that the 505 delighted me with in the first place. Lowell George’s cover of I Can’t Stand the Rain on Thanks I’ll Eat it Here (still my favourite version of this song’s many covers) is tonally convincing, effortlessly spacious and unquestionably hi-fi but more than any of these things, it’s a head nodding, grin inducing beauty of a track that grabs and holds your attention and has you wanting to keep listening. This is a technically impressive device but that technical excellence is secondary to an innate desire to make music.
Conclusion
It’s this consistent ability of the Sigao Drive to find and extract musical joy plus the impressive flexibility it offers in terms of partnering equipment that marks it out as rather special. All of a sudden, it’s possible to use amplifiers that might not have featured as candidates for use in an active system before (a dealer I spoke to recently was employing one to make an Accuphase system active) and do so knowing that the result is going to be effective. The Sigao Drive’s function might not be terribly easy to explain but the results it produces are far easier to understand and appreciate.