We stock a large range of RCA connectors that can be available with your cables. You are welcome to choose these connectors based on prior experience you have, on recommendations and reviews you may come across, or based on their materials, your budget etc. From our side, we are happy to give our recommendations, but these will be based on technical assessments of the individual connectors, rather than on a perception of “how they sound”. It goes without saying that RCA plugs (and electrical connectors in general) cannot be evaluated the same way as cables, by simply examining their electrical properties. Their role as mechanical structures is vital to their performance (and the performance of the system as a whole) and their assessment cannot be reduced to the conductivity of their materials. Furthermore, unlike the insulated conductors /wires of a cable, the metals that are used on electrical contacts WILL react chemically to environmental conditions (with the reaction being dependent on the consistency of the air and the metals they will come in contact with). So please do keep these factors in mind when weighting the benefits and drawbacks of the individual connector designs and do not simply assume that connector will perform better by simply being made of pure copper or pure silver

This type of connector is still the industry standard for singled ended / unbalanced audio connections in Hi-Fi. RCAs come in many variations but their core design has remained largely unchanged since they first appeared in the 40s. The interface of all standard RCA plugs, feature a central pin conductor (signal) and a metal collar (signal ground). The 2 contacts are separated by an insulator while the body of the connector can be a metal extension of the ground collar, an isolated metal structure or simply a plastic support structure. RCA connectors can also feature a metal or plastic outer sleeve which can offer additional support and protection (and is some cases it provides EMI/RFI Shielding).

Despite its popularity and widespread use, the RCA connector is far from an ideal option for applications that deal with low level, analogue audio signal (phono and line level). Its conductors have a very high mass, disproportional to the requirements of the current it handles & its shape and geometry result to unfavorable, capacitive and inductive properties. However, some significant alterations to the classic deign took place during the last 20 years that gave new momentum to the RCA connector and made it far more relevant and suitable for analogue Hi-Fi applications.

There are many factors that affect the performance of connectors. Simply choosing a connector because it is made of pure copper or pure silver does not guarantee that it will perform better than a budget, brass alternative. In this section, we attempt a small introduction and a brief assessment of various RCA connectors that we have chosen to use on our cables.

Neutrik Rean NYS373:

In our opinion, this is the best low cost option. These connectors have a slim and long profile; they feature gold plated contacts and a rubber boot for strain relief. Neutrik have made a significant improvement on them over the past few years that may not be particularly obvious. The ground contacts -made of a higher than average quality brass (H62) - have adopted a very effective profile in order to minimize the contact resistance by adjusting to the small tolerance variations of the RCA sockets. The thinner ground contacts have the ability of slight expansion and retraction. The ground collar is slotted with 2 of the plate parts skewed  inwards, in order deliver a spring like effect and ensure that they neither cause wear to the socket nor have a  loose fit. This may appear like a small detail but given the importance of contact resistance and the mechanical factors that determine it (in the context of tolerance variations of the RCA sockets and over a period of time / mating cycles) this feature helps such a modest connector outperform plugs that have luxurious presentations and far higher price tags.

Although these Neutrik Rean RCAs are very basic connectors, they have become an industry standard and we strongly believe that in such a price range they cannot be matched by other alternatives. No, we would not describe them as audiophile connectors but they are much better performers than many luxury RCAs that one can find fitted on “audiophile” cables.

Switchcraft 3502A:

This is a US manufactured connector, very popular among users of vintage audio equipment. Minimal & durable construction. It features a solid, nickel plated copper alloy pin. This is the most popular version of the connector. However a gold plated version  is also available (3502ABU) as well as a nickel one with smaller profile (3502). We are not particularly keen on nickel plated connectors, however, if your equipment already use nickel sockets and you are familiar and satisfied with Swithcraft RCAs, they are a very good choice of connectors.

Deltron 332 / 330:

Deltron is one of the oldest and most well known British manufactures, designing and producing audio connectors since 1946. Deltron RCA connectors are manufactured in the UK from turned brass. The 332 version features a hollow central pin and a patented T-slot ground contact which allows maximum contact even on undersized phono sockets. The connector is finished with a flash gold plating (nickel free). The 330 version features a silver plated central pin and nickel outer shell. Their very small profile is ideal for use on equipment where space is limited. Overall, a very well machined, classic RCA connector.

We do stock a large variety of “classic type” RCA connectors. However, despite their low cost, we consider the above offerings by Neutrik Rean, Deltron and Switchcraft to be some of the best performing options. Their design and choice of materials show a very good understanding of the real priorities for a reliable connection and they have proven themselves over the many decades in both the pro-audio and the consumer electronics industry. They do not aim at impressing with their appearance, nor with constant references to high purity materials

The locking barrel was the first, major innovation that occurred on the RCA design. It effectively deals with the most common issue of RCA functionality. As mentioned previously, connector are not simply parts of the electrical circuit; they are also mechanical structures. Their electrical properties and their success as part of the electrical circuit depends on how well the mechanical properties of their materials are suited for the intended function. The metal ground collar of the RCA (which is often an extension of the RCA body) is a large receptacle. It needs to have the ability to expand and retract, ensuring consistent pressure on the female socket, in order to maintain low contact resistance.

Most of the metals used to create the ground collar of an RCA do not have the ability to retract. The result is after a few mating cycles, the contact resistance increases which starts becoming evident over the time. Contact manufacturers have addressed this issues by developing special contact profiles to improve the retraction ability of the ground collar and they have introduced alloys with more suitable mechanical properties. However, the locking function is the only one that can ensure a consistent, low resistance contact over a very long period of time and in wide range of situations where tolerance differences between the mating parts may occur. 

The locking function: The threaded shell of the connector screws onto the body of the RCA while gradually applying  pressure onto the jaws of the ground collar, effectively acting as a clamp onto the RCA socket.

Remember, the aim of the locking mechanism is to maintain low contact resistance, not to prevent the cable from being pull out! Do not over-tighten the locking barrel.

Not all locking RCAs have exactly the same design or use the same materials. So, there are slight variations on the way they function. Sometimes the outer barrel is a two part construction and sometimes a single piece. In some cases, the locking mechanism may require more force (i.e. when the ground collar is formed by thick brass plates), while in others a gentle rotation is sufficient (i.e. when the ground contact is formed from a softer material like pure copper or silver)  In some cases, the ground jaws are relaxed enough to slide onto the socket without any resistance - when in the “open position” - and once the barrel is locked the jaws will clamp onto the socket. In other cases the jaws may offer adequate contact even in “open position” and the locking barrel is used to adjust the pressure after extended period use, or when the repeated connecting/disconnecting has caused a relaxation of the jaws from their original condition.

We offer a selection of locking RCA plugs to meet all budgets but always ensuring that they will perform to very high standards. Our aim is not to stick to appearances and brand names but to focus on the aspects that offer an advantage in terms of performance within a given price-range.

Carbon fiber locking RCAs:

These extremely well made MS Audio connectors feature rhodium plated Tellurium copper contacts and Teflon insulation. The outer locking barrel is finished with a  carbon fiber layering. Excellent shielding ability and very good overall performance.

Although the carbon fiber finish on these connectors may be appealing, we have not selected them for them for cosmetic reasons. The use of the hollow Tellurium copper signal pin, Teflon insulation and the smooth locking function helps them stand out from similar products..

There are many lower cost alternative options to these RCAs, either in regards to the locking barrel function or in terms of their overall appearance. However, the differences in their construction and performance are substantial. We have tested dozens of connectors that appear almost identical to them but the actual differences between them are very apparent. The majority of similar examples are made of alloys that either contain a very small percentage of copper or no copper at all and the differences the exhibit in terms of their thermal and electrical conductivity cannot be ignored.

The single point ground design is the most important structural innovation that happened to RCA connectors since the 40. It effectively replaced the metal, ground collar with a ground pin and by reduced the overall active mass of the connector by up to 90%.

An introduction to single point ground RCA plugs -  Eichmann / ETI Bullet plug.

The original bullet plug brought the most radical transformation of the traditional RCA connector design and it introduced it in the market with great success. The main elements of this design are nowadays featured on many connector products that are available from various manufacturers.

The basic principle of the Eichmann Bullet is very simply but it is also a radical departure from the traditional RCA design. A typical RCA connector emulates a coaxial design. It has an outer ground ring /collar which secures on the outer part of the RCA socket (effectively making contact on multiple points).  In the case of the “Bullet plug” the ground ring/sleeve and body of the traditional RCA has been replaced by a metal pin that makes contact on the outer (signal ground) part of the RCA socket on a single point. On the majority of the “single point ground” designs, the ground pin/contact is mechanically supported by the plastic insulation of the connector.

Regardless the materials used, by design, a typical RCA plug matches the structure of a  coaxial cable which features a central signal conductor and a tubular shield. Symmetrical cables (or cables with a balanced structure) are usually better matched with pin based connectors (I.e.DIN and XLR). However, symmetrical / balanced cables for “unbalanced audio” is a relatively recent development and as a result such cables are now frequently used on single ended connections where most home audio appliances are traditionally fitted with RCA sockets.

The creation of the bullet plug however, was not a direct consequence of the need to find a suitable match for symmetrical cables in unbalanced applications. Based on the submitted patents the aim was to minimize the energy storage and reduce the inductive and capacitive effect of the connector on the signal by using an optimal ratio between the signal (send) and ground (return) conductors and by reducing the mass of the contacts. Further more the “single point ground” design of the Bullet plug has also resulted to minimizing the Eddy currents at the part of contact with the mating sockets by reducing the contact area to a single point.

Balancing the mass of the signal and ground contacts (control capacitance and inductance), and creating a single point ground (eliminating Eddy currents) are not the only benefits of the bullet plug. The lower metal mass of the connector meant that the choice of metals that could be used as conductors at affordable cost, is much wider. The use of pure silver and copper on both contacts and high quality types of plating is now possible at reasonable production costs; hence most single point ground RCAs tend to have a much better selection of materials.

Of course, since the introduction of the original Bullet Plug almost 20 years ago, the design has been adopted and further developed by many manufacturers. The initial collaboration between Keith Louis Eichmann and ETI that produced the Bullet plug has ended and currently KLE and ETI have their own separate lines of “Bullet Plugs”.

KLE Innovations Harmony Plugs

More details on KLEI plugs here

Star-line RCAs

More details on Star-Line RCAs here

WBT NextGen

More details on WBT NextGen RCAs here

So, how is a great RCA connector defined? It is one that can achieve very low, consistent impedances, in a wide range of conditions and over a long period of time/large number of mating cycles. It is also one that has the ability to isolate the signal from the its surrounding / external environment. The selection of materials, tolerances, shape, profile and the overall structure, only have a meaning when they can contribute to the above aims.

As mentioned above, we do not sell connectors, and we have no intention to steer our customers towards certain options. We simply want to offer an informed and impartial advice in order to help you with your decisions. Personal experiences can be is an invaluable source of information. However, they do not replace scientific knowledge. We are certain that many of you have used connectors that we would describe as inadequate, without having any issues with them after many years of use. Others may find that after a relatively short use, your connectors began to wear off or have a less than optimal performance. One should manage his/her expectations based on how the connectors are used. So, if you intend to frequently switch your cables among equipment or expect them to endure a relatively “rough handling”  choose your connectors accordingly. Some materials (both plastics and metals) may have excellent electrical properties. This does not mean that their mechanical characteristics are always up to the task.

Yannis Tome Audio Cables, 36 Dinas Terrace, Aberystwyth, Ceredigion, SY23 1BT, UK - email: info@back-promo.co.uk

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