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Home / Product Category / Whole House Audio / Volume Controls / In-Wall Volume Controls / OSD Screwless Rotary Knob Volume Control 300W High Power Impedance Matching SLK300 Decra Style Wall Plate Snap On

OSD Screwless Rotary Knob Volume Control 300W High Power Impedance Matching SLK300 Decra Style Wall Plate Snap On

Product code: SLK-300

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OSD Price: $59.99
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Features & Specifications

. Screwless Decora style impedance-matching volume control for whole house audio systems and dedicated audio zones
. Rated at 100 Watts per channel with minimal bass roll-off
. Impedance-matching feature stabilizes the ohm load so parallel connections of multiple volume controls can be installed without damaging the amplifier
. Front-mounted adjustable jumpers allow easy adjustment when multiple pairs of speakers are connected to a single receiver or amplifier
. Accepts up to 14-gauge wiring and fits in a standard gang box with a depth of 2.9”
. Includes junction box and screws as well as white, ivory and almond trim plates to match any room décor
. Precision electronics provide low distortion and a ruler flat frequency response
. 12-step linear rotary-style knob for a wide range of listening volumes

More about Impedance Matching

Now you can match your favorite decora light switch with screwless volume control. All speakers have an impedance rating, typically 8 ohm for a pair of home speakers. To operate in the safest mode, most standard amplifiers and basic two-channel receivers are rated for an 8-ohm incoming load. To operate safely and consistently, the amp needs to see an 8 ohm load, and that’s where speaker selectors and impedance-matching volume controls come into play.

In a basic multi room system, only a Speaker Selector is used to connect the speakers to the amplifier/receiver. Not only does the Speaker Selector allow you to connect multiple speakers to the amplifier but also adds internal Impedance Protection which is enabled by a manual protection switch. Both our ISS and DSM series Speaker Selectors feature internal Resistors that protect the amplifier. The down side is that the power rating normally 140 watts is cut in half when the protection switch is enabled so rated at 70 watts with protection.

In a standard multi-room system (using Impedance Matching VC) you will typically have an amplifier/receiver, a speaker selector with 4 to 8 zones, and volume controls connected to all the speakers. Impedance-matching volume controls provide more precise protection for the amplifier/receiver versus the protection built into the standard speaker selector. Plus with the protection switch in the off position you will have the maximum power handling capability of the respective speaker selector. It is important that the protection switch is turned off when using the Impedance matching Volume Controls.

Most impedance-matching volume controls feature three standard settings: 1/2x, 4x and 8x, while some add a 16-ohm setting like our VMS series. These settings correspond to a chart in the owner’s manual based upon the type of amplifier (4 or 8 ohm) and the number of 4 or 8 ohm speakers that you will be using in the multi-zone/room/speaker system. You can use both 4 and 8 ohm speakers when setting up your system. But you need to count a 4 ohm speaker as two 8 ohm speakers when calculating your Impedance setting.


2 Questions & 2 Answers
from Berthoud, CO asked:
November 6, 2019
I am very interested in your volume control products and want to pick the best product you have. I like the SVC205 with the dedicated on/off switch for $40.00 and wonder why this switch SLK300 is higher priced without the on/off switch.

 I also wonder whether rotary or slider is a better switch type. I plan to install eight volume controls for my system: one off the "A" zone and 7 of my "B" zone after a Niles SI1230 amplifier.

The amp has 6 dedicated "zones": 5 of which will power pairs of speakers and one will power a split set of single Mono speakers each with a volume control.

It seems like I should set the impedance on the switches from the amplifier on 8 and the switch direct from the receiver on 1. 

Does this set up sound reasonable? Do any of your other VC's have a dedicated OFF switch like SVC205? Which is your best quality switch?

1 Answer
Hi Bill:

The SLK300 features a Screwless Decora outer plate design. The SVC205 is the only Impedance Matching Transformer type that has an on/off switch.  Our best sounding Volume Control is the VKR120/SKR120 Resister based Volume Controls. It has a broader Frequency Response with no High or Low-end roll-off. It does not feature Impedance Matching like the SVC300/SVC205 Transformer Type and OVC300 weather-proof version. The primary purpose of the Impedance Matching Volume Control is to provide protection first and controlling the volume levels secondary. Only the SVC205 Impedance Matching Volume Control has an on/off switch. All other Impedance matching Volume Controls do not disconnect even though music is inaudible after turning the volume knob all the way counterclockwise to the last click where it stops. That is why we recommend using the Impedance Matching Volume Controls with Speaker Selectors and using the on/off when not using a zone. Back to your application, since you are using dedicated amplifiers for five pairs of speakers, if you sued the SVC205, the Impedance Setting would be 2X for all five Volume Controls. The setting would be the same for the two additional speakers for ZONE 6, with the two DVC speakers wired in Parallel from the AMP. If you have not purchased the Niles Amplifier, you might want to check out our MX1260 12 channel Amplifier with Dual Buss inputs/outputs. And features signal-sensing turn-on by zone. We offer a 10% discount on everything you buy from us along with free freight. Ironically we have three new Multi-Channel Amplifiers coming in January; 4 zone/8 channel, 6 Zone/12 channel, and also an 8 Zone/16 channel Amplifier. Also, check out our new NERO Link Wi-Fi Preamp App controlled device.

Want to know more;


Submitted by: Tim Leahy on November 13, 2019

Colin R.
from Fredericksburg, Texas asked:
July 26, 2019
Is this product rated at 300 watts @ 8 ohms per channel or 150 watts per channel?
1 Answer
Hi Colin:

These are rated 150 watts RMS, 300 watts Peak per channel. The same for the OVC300 (the outdoor version) and SVC300. The SLK300 is the screwless Outerplate version. Also the same as the Volume Control used in our SSVC series of Speaker Selecter with internal Impedance Matching Volume Controls


Submitted by: Tim Leahy on July 30, 2019

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