Impedance of TC Electronic cabs

Discussion in 'Amps [BG]' started by magic papa, Apr 5, 2014.


  1. magic papa

    magic papa Gold Supporting Member

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    Hi,

    Would anybody be able to shed some light on TC Electronic amp/cab matching? They don't seem to publish these values, I thought such information would be crucial, but whatever :rollno:

    They state that an BH500 or RH750 can drive up to 3 212 cabinets :)confused:), while on the back on the amp it clearly states 4 ohm minimum. What is the impedance of these cabs then? 12 ohm?

    The "Cabinet Configurations" on their website don't make much sense to me. Do they make any sense to anybody? (http://www.tcelectronic.com/bh500/ scroll down to "Cabinet Configurations" section).

    Many thanks
    MP
  2. chris_b

    chris_b

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  3. magic papa

    magic papa Gold Supporting Member

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    Thanks a lot. Yes, it makes some sense now. Interestingly the Blacksmith is listed there as 2.66 minimum load, while the website claims it can drive 4 cabs (?).

    Why can't these people just state the correct value on the back of the amp or in a manual. This is what civilised people do :scowl:

    Anyway, I was craving for a TC rig, but now I'm reluctant to spend my money with a dodgy manufacturer. Even heard a statement that the RH head can drive 3 x 8 ohm cabinets but as long as they are the TC ones. Talking about snake oil... :rollno:
  4. xbud

    xbud Supporting Member

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    The TC Electronic Cabinets that I had, used 16 Ohm drivers and were wired in parallel. I'm not an expert but since the drivers themselves have a higher Ohm rating they are able to safely pair them as they state down to a 2.67 Ohm load ? I have run this same setup configuration with an 8Ohm cabinet and 4 Ohm cabinet for a 2.67 Ohm load through my GK MB800 and it didnt have any ill effect (Talk about loud). It also is rated as a 4 Ohm minimum. So I am pretty sure that the minimum ohm rating is because of different manufactures using lower Ohm rated drivers that may be wired in series causing more of a load compared to the drivers and wiring in the TC Electronics cabinets.
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  6. magic papa

    magic papa Gold Supporting Member

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    Two 16 ohm drivers in parallel should be exactly the same as two 4 Ohm drivers in series. Both yield 8 Ohm; the impedance of a single driver shouldn't matter (as long as all the drivers are the same).

    I think the amp can indeed go down to 2.66 ohm and TC just didn't mention it in the marketing materials nor on the back of the amp. Perhaps in order to get people to buy TC cabinets they tried to make an impression that they had magic properties and wouldn't load the amp as much as the other cabs. I can't see any other reason.

    TC are known for their dodgy marketing practices, but I this time they were just mathematically incorrect.
  7. 4-string

    4-string Supporting Member

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    The "magic properties" are that the TC RS cabs are not 8Ohms, they are 10Ohms or thereabouts.
  8. magic papa

    magic papa Gold Supporting Member

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    Are you serious?
  9. 4-string

    4-string Supporting Member

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    Yes, of course. I don't remember the details, but the BGM test/review stated something like that.

    Which is why TC can safely recommend using 3 of their own cabs, but won't guarantee the result if you use 3 cabs from other manufacturers.
  10. magic papa

    magic papa Gold Supporting Member

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    Where did they get the drivers to make a 10 ohm cab? Perhaps this is what the "custom Eminence" speakers are - just a few more windings on the coil and magic happens.

    What do you do if you blow one up? Get one from Denmark or build one yourself from Lego blocks?

    Anyway, this thread was very educational for me so far. I need to stay away from TC Electronic. Portaflex it is then...
  11. 4-string

    4-string Supporting Member

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    Good question - I'm sure dealers can get replacements if needed?

    The RS series cabs are great, especially the 210 IMO.
  12. magic papa

    magic papa Gold Supporting Member

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    They do sound good, I tried one in the shop (212). Having said that I rarely tried a cab in the shop that didn't sound at least half decent. It's the band situation where good cabs can be distinguished from the crappy ones.

    Considering parts availability on Australian market I think I need to stay clear from any non-standard contraptions. Plus TC Electronic employ way too much smoke and mirrors. They lie about the power output in the amps, they lie about the impedance. I can't be sure what I'd be getting if I decided to get a TC rig.
  13. 4-string

    4-string Supporting Member

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    Sounds like TC is not for you then. :)

    I'm not sure how relevant nominal impedance really is, or how precisely this is stated from other manufacturers for that matter, but since you're down under I appreciate that getting spares might be a bit tricky. :)

    Other manufacturers lie about output power as well. SVT 7PRO was measured at 763 watts in BGM, not the marketed 1000w. Mesa has now updated their specs, so the M9 which used to be marketed as a 900 watts amp is marketed as a 600 watts amp. AFAIK, the latter was changed after the early amps had issues. FWIW.

    If GK is available in Australia I can really recommend the MB800. Small and very lightweight, sounds absolutely great (but way more modern/bright/deep than TC) and loud as heck. Also did very well on BGM's bench test, and that tiny amp actually delivers the announced 800 watts at 4 Ohms. Great value around here at least, don't know what they cost in Oz though.
  14. magic papa

    magic papa Gold Supporting Member

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    Oh c'mon. TC beats them all. RH750 - merely 200W instead of advertised 750W. And that's according to TC, not sure what the BGM would tell.

    763W for a 1000W Ampeg although still poor is not as bad.
  15. 4-string

    4-string Supporting Member

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    So, it's about the percentage, or degree of lying instead of the principle? At least TC has a reason for what they are doing, other than to prevent failure. ;)

    236w is what the BGM test was, and that was entirely in line with what TC expected. Too bad they didn't do their marketing differently when they introduced the RH heads though.
  16. LouBass

    LouBass Supporting Member

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    My MB Fusion 800 into 2, TC RS210s sounds fantastic fwiw. I started with an RH450 but I'm so much happier with the GK.
  17. chris_b

    chris_b

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    TC is not a "dodgy" manufacturer.

    The cabs are just plain 8 ohm and 4 ohm cabs and the amps go to 2.67 ohms.

    Is that where the "snake oil" comes in? Except it isn't "snake oil". That's just what they are designed to do, go to 2.67 ohms. So 3 of any manufacturers cabs can be used.

    The 3 cab thing was just marketing. They probably sold a lot of cabs on the back of that and I haven't heard any users complaining.

    Don't be sidetracked. If you like the tone of a TC amp or rig then get it. TC is quality gear and designed and built as well as anything else in the marketplace.
  18. JimmyM

    JimmyM Supporting Member

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    The 7 Pro was measured a week after that BGM article by Tekdiver and it hit 1000w. With the preamp. Twice.
  19. JimmyM

    JimmyM Supporting Member

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    Have you tried it with 3 of another manufacturer's cabs? People who have say it doesn't work. And when have we seen another micro head that doesn't cost a fortune that does below 4 ohms? Also, as far not being snake oil, taking a 236w RMS amp and claiming it does 450w or 750w just because you added a lot of compression and high pass filtering to it is the very definition of snake oil.
  20. 4-string

    4-string Supporting Member

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    Not quite. I found the test (BGM issue #6), and the RS210 and RS212 are 10.54 Ohms and 11.54 Ohms respectively according to BGM measurements.
  21. drpepper

    drpepper Supporting Member

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    I think the point that fundamentally misunderstood in these discussions is that impedance ratings on almost all cabinets are NOMINAL; they are labels, not statements of measurements. These labels are used, in effect, to place a cabinet is a class, for guidance, not to tell you precisely how many ohms you're buying, where you're being hoodwinked to find that the measured impedance is different from the label.

    Impedance is not a constant number. It changes with frequency (significantly). Measurement is made across the frequency spectrum, and rating concerns itself with the lower threshold. A "properly labeled" 4 ohm cabinet can be measured to be anywhere from 3.2 to 6.3 ohms and an 8 ohm cabinet from 6.4 to 12.7 ohms.

    While it isn't constant, impedance is consistent (enough) between different units of the same speakers. That being the case, whatever the exact numbers are, the fact is that TCE knows that the RH heads can safely be used with 3 of their cabinets. Because properly labeled cabinets from another maker can have lower impedance, they might not be safe. Improperly labeled cabinets, even more so.

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