OSD Audio’s VMS100 is an impedance-matching volume control for adjusting the volume of a pair of speakers within a whole house audio system. Ideal for dining rooms, saunas, porches or other areas of the house where you want to add sound, the VMS100 maintains the full hi-fi audio frequency response with no low frequency roll-off and is equipped with the same features of volume controls that cost twice as much. Rated at 100 Watts peak, the volume control includes adjustable jumpers to add up to eight pairs of 8-ohm speakers simultaneously, and the impedance-matching feature helps stabilize the ohm load going back to the amp or receiver to avoid overheating. This is a complete volume control kit that fits into a standard single-gang box and includes the VC, junction box, screws and assorted color trim plates (white, ivory and almond) so you can choose the color that best matches the room. Compatible with almost any dedicated audio zone or whole house system, the electronics inside the VSM100 are designed with a ruler-flat frequency response while the 12-step slider provides noise-free volume control and a wide range of listening volumes.
- Decora style impedance-matching volume control for whole house audio systems and dedicated audio zones
- Rated at 100 Watts peak with minimal bass roll-off
- Impedance-matching helps stabilize the ohm load to avoid overheating
- Accepts up to 14-gauge wiring and fits in a standard gang box with a depth of 2.9”
- Includes junction box, screws and white, ivory and almond trim plates to match any room décor
- Precision electronic design provides low distortion and a ruler flat frequency response
- 12-step linear slider for pop-free control and a wide range of listening volumes
- Installs easily and works with almost any audio system
What Is Impedance Matching Volume Control?
Impedance is a measurement of resistance to alternating current. Speakers are specified by impedance, and a common value is 8 ohms. When you’re connecting multiple speakers to a receiver or amplifier, you need to stay above the amp’s minimum load requirements because going below the impedance rating can overheat or even damage expensive equipment. Volume controls such as the VMS100 have selectable impedance so you can match the impedance with the number of speakers being controlled with the capabilities of your amp. A basic multi-room system will typically have an amplifier/receiver, a speaker selector, four to eight pairs of speakers, and volume controls. Impedance-matching volume controls feature three settings depending on how many speakers you are connecting. For one to two pairs of 8-ohm speakers, the setting is 1/2x; for three or four pairs of 8 ohm speakers, the setting is 4X. Volume controls do not add gain (volume) to your speakers but simply attenuate the volume up or down. During setup, you'll set the source volume to its optimum level, then the volume control turns the sound down to inaudible levels.
Warning: California's Proposition 65
This product can expose you to chemicals, including vinyl chloride, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov.
- Volume Control Type: 100W Impedance Matching Slider Style
- Power Handling: 100W Peak; 50W RMS Per Channel
- Frequency Response: 20Hz - 20kHz
- Total Attenuation: 52 dB (Max)
- Steps: 12 (Make Before Break)
- Impedance Matching for 1/2, 4, 6, or 8 Pairs of Speakers
- *Can be Used as Non-Impedance Matching if Leaving Default on Jumper Setting at 1X
- Wiring Requirement: Up to 14 Gauge Wire
- Removable Input and Output "Quick Connect" Phoenix Connectors
- Fits in a Standard Single Gang Box - See LV1 for Mounting Bracket
- Unit Dimensions: (L x H x D) 1.62" x 2.5" x 2.5"
- What's Included: White, Ivory and Almond Plates, Inserts, Screws, and Slider
- Additional Colors Available: Black or Brown
- Warranty: 5 Years
31 Questions asked
What's on your mind?
Bryan • 12/17/2019, 2:17:43 PM How exactly is the impedance being matched? My setup is the same exact configuration as the example in the instructions, only difference being I have 6 Ohm speakers. I am not measuring the expected impedance that my amp is seeing when using the 4X mode. In order for me to have my amp see roughly 6 ohms is setting both controllers to 16X, why is that? When i only have one controller connected in 16X mode i get 12.6 ohms, then connecting the other one i get i get 6.3 ohms. which makes perfect sense b/c 12.6 in parallel with 12.6 is 6.3. But why is the impedance only 12.6 when in 16X with a 6 ohm speaker? Just trying to figure out if my logic is correct or if there is something i'm missing. Also i noticed the impedance drops an ohm or two from low to high volume, is that expected?
Customer Service • 12/17/2019, 2:17:43 PMHello Bryan, Impedance is not constant or consistent, it varies based on frequency and load. The load itself is also varying based on the magnetic to electrical efficiency of the load (speaker?). In addition, the cable used can affect the impedance and the crossover can affect the impedance. The general rule of thumb is to have a match between speakers and amplifier that is within 0 to +2 Ohms above the rated load. So a speaker rated at 4 - 6 ohms should be connected to a source rated between 2 - 4 ohms. The important part is to not allow the amp to see less than the 4 ohms. The difference being measured when you connect more or less equipment to the VC is most likely due to the individual variances of each of the different pieces of equipment all added together. DT 2703
mTurns • 12/17/2019, 2:17:43 PM I have the VMS 100 and want to run 3 outdoor speaker and (1) in door speaker off the controler. Do I connect wires together and place them in the wire connections?
Customer Service • 12/17/2019, 2:17:43 PMmTurns: I would not recommend connecting all four pairs of speakers through a single Impedance matching Volume Control. Worse case I would have you add at least one more Volume Control like our OVC300 to connect to two of your outdoor speakers then have the VMS100 connect the third pair of outdoor with the Indoor pair then make sure the Impedance Setting on both units is 4x. Are you using a dedicated Amplifier (like our AMP200 vs AMP120) or attempting to run all four pairs off a second zone output from a Audio/Video Receiver? Most AVR second zone output do not want you to load up multiple speakers even if it is Impedance matched with Volume Controls. The more speakers you add to a single device or by adding even the two volume controls costs you output unless you have the Current needed and that depends on your Amplifier setup you have. TL/3132
Ross Herndon • 12/17/2019, 2:17:43 PM Is a speaker selector box a necessity or can I just wire straight to the amp and control on/off/volume at the wall controller? When on its lowest setting, will the volume be off?
Customer Service • 12/17/2019, 2:17:43 PMHi Ross, It depends on what you're running. If you're just running 1-2 pairs of speakers off the amp, you shouldn't need the speaker selector unless you want to have individual on/off capability and volume control for each pair of speakers. The volume control at its lowest setting will not completely turn the the music off, just very low. How many speakers are you planning on running and what amp would you be using?
Quincy Kirt • 12/17/2019, 2:17:43 PM Hi, I'm running four sets up speakers in zone 2. Each connected to an impedance matching volume control. ( VMS 100) I set the switch to 8. Is that OK? I've noticed the instructions guide gave a brief summary on how many pairs and what to set each volume control too. The summary was 1-2 SW-2, 3-4 SW-4 5-6 SW-8. I fall in the 3-4 range but I didn't set them to 4. I set them to 8.
Customer Service • 12/17/2019, 2:17:43 PMHi Quincy: That is a loaded question, I am assuming when you say Zone 2 you are referring to a Speaker level output on your Audio Video Receiver where you have connected four pair of speakers all in parallel with a VMS 100 on each pair and you have set the impedance Matching setting to 8X. So how does it sound, are you having to turn up the volume quite a bit on your receiver to get enough output? Typically most Audio Receivers recommend going with a external amplifier when connecting any external device like a speaker selector or volume controls which usually means you are connecting more than just a pair of speakers. Most of these do offer both a Speaker Level (direct connect to the speakers) or Signal Level (Pre-amp output to External amplifier). If you had connected the four pair to a High Current Power Amplifier like our AMP-200 I would recommend the setting be at 4X on all four Volume Controls. The 8X setting without an external amplifier would be like operating your system in safe mode, just not sure if you will get enough output to power all four pairs at the same time. Please feel free to contact me at [email protected] and provide me a little better description of your layout so I could provide you with a better answer. TL/3997
Matt • 12/17/2019, 2:17:43 PM Hello, I recently ordered and received 2 volume control units (VMS100) for two pairs of 8 ohm speakers. Before installing the volume controls, the speakers operated fine from a single receiver with A+B zones. If I am hooking up the volume controls to the exact same setup (same receiver, same 4 speakers) just splicing the speaker wire in the wall to accommodate the volume control, would I choose the 2x jumper setting or should I be able to use 1x, knowing the receiver worked before introducing the controls? Thanks Matt
Customer Service • 12/17/2019, 2:17:43 PMHI Matt: I would set the VMS100 to 1X which should by pass the impedance protection. You are only adding the Volume Controls so you have more control over the volume in the actual zone. These volume controls are attenuators which means you are starting with your volume from the source than just turning the volume down. You are not adding any gain, these are passive devices. If you were not having an issue playing both speakers at the same time before the Volume Controls than 1X setup would be best. The 2X setting is only if you need the Volume Controls to control the impedance which does not sound like the case. TL/4255