RS212 impedance question

Discussion in 'Amps [BG]' started by Webtroll, Feb 4, 2014.


  1. Webtroll

    Webtroll Rolling for initiative Supporting Member

    Joined:
    Apr 23, 2006
    Location:
    Austin, TX
    I bought a TC Electronics RS212 and I love the tone and the light weight and am wanting to buy a second one, but the impedance is a little strange to me. It is rated for 8 ohms, but on a meter it reads 5.8 ohms. I emailed TC Electronics and was told that 5-6 ohms is normal on a multimeter, but that the impedance varies with frequency.

    While I do not doubt this, I still worry about using the cab (or cabs if I buy more) with my non TC Electronic amplifiers. Can anyone shed any light or experience on this? I run my Crown XTi 2000 bridged which has a 4 ohm minimum load, so 2 of these cabs metered will be below that. Will I be running the risk of damaging the amp or will the impedance take place at frequency and not be a concern?

    My other amps at this time are a Boogie D-180 (all tube) and Boogie Pulse 360 (solid state power) all of which have a minimum 4 ohm load. The Crown will drop to 2 ohms per channel if split.
  2. Selta

    Selta

    Joined:
    Feb 6, 2002
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    Somewhere Far Beyond
    Disclosures:
    Uncompensated endorsing user: EBMM
    It's an 8 ohm cab. All cabs will measure differently when you measure DC resistance, because you are measuring at a fixed frequency, and not the actual inductance. Impedence varies by frequency.
  3. Webtroll

    Webtroll Rolling for initiative Supporting Member

    Joined:
    Apr 23, 2006
    Location:
    Austin, TX
    Thanks for the speedy response! So safe to use as a regular 8 ohm cab and all is reading as normal. I still wish I could use 3 of them for my Boogie head, but that seems ill advised.
  4. Selta

    Selta

    Joined:
    Feb 6, 2002
    Location:
    Somewhere Far Beyond
    Disclosures:
    Uncompensated endorsing user: EBMM
    Yeah, that puts you a fair amount below the min load. I personally wouldn't do it. The D-180 may be more forgiving about it than the Pulse, if you had to do it with one of those two.
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  6. B-string

    B-string Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    All is normal, you read the DCR. There are actual impedance meters but plotting the impedance across the frequency band is the only reliable way to determine the "nominal" impedance.

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