TC Electronic RH450 - Cuts out during gig (possibly heat related)

Discussion in 'Amps and Cabs [BG]' started by Howard Page, Sep 9, 2021.

  1. Howard Page

    Howard Page

    Sep 9, 2021
    I have a RH450 bass head and it cut out at a reasonably large festival gig last weekend when running on about half volume (It lasted around 20 minutes ish). Only th epower amp failed, the lights and all other functions were fine and the DI out wasn't affected - just no sound form the cabs. I did check the speakon cables and they were fine and secure. Back at home I opened the case and found the fan wasn't working when the amp was switched on - it worked fine back home. I bought a replacement fan but when I removed the old one I found that it still works when connected to a separate 12V supply so appears to be working.

    I was wondering, does the fan come on permanently or does it only come on when the amp gets hot?
    And has anyone got any suggestions on another possible causes?

    Thank you in advance!!!! Howard
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  2. Aloe


    Apr 10, 2016
    well, to verify it's the heat protection mode, do you recall if the front panel displayed a 'H' letter when this happened? if yes, that's it. if not, that's probably something else.

    please note that the heat protection mode may also happen if the cabs' load is <4 ohms and volume is high. any chance your cabs do something like 3.8 together (it happens sometimes)?
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  3. Howard Page

    Howard Page

    Sep 9, 2021
    Hi Aloe, thanks for your reply. I use a TC 2x10 and a TC 2x12 daisy chained via speakon - they are 4 Ohms each so I believe they're in series? I did have the amp much louder than usual due to the size of the event..... It lasted around 20-30 minutes before the sound failed. I checked the speakon connections but they were fine. It's been fine ever since played a low volume at home.
    I don't recall a H on the front I'm afraid - But I had shades on instead of my reading glasses :cool:
  4. Aloe


    Apr 10, 2016
    I believe, that's a two-ohm load, so that might work on low volumes (according to amp's manual), but no way on higher. TC doesn't recommend running a 2-ohm load with this amp anyway.
  5. Agreed with Aloe your amp has a 4ohm minimum load and you've got a 2ohm load with 2 4ohm speakers. You should only be running a maximum of 1 4ohm cabinet or 2 8ohm cabs with this head.

    Alternatively consider a head capable of 2ohm load.
  6. Howard Page

    Howard Page

    Sep 9, 2021
    Thanks for that - I just checked and they are actually 8 Ohms each - so should be 4 Ohms together. I've been using an Ashdown RM800 for the past few years with no issues - same two cabs but it does have two speakon outputs.
    I know the fan is permanently on with the RH750 - Do you know if the fan is supposed to be permanently on with the RH450 also? If so I could look for an alternate 12V feed from the board to wire it to. Thanks again!
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  7. Inara

    Inara Fierce Fun Fretless Female

    Jun 12, 2017
    Seattle, WA USA
    Which 212 and 210 TC cabs exactly? The ones I've seen and that were designed to pair with the RH450 were 8 ohm cabs.
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  8. Howard Page

    Howard Page

    Sep 9, 2021
    They are 8 ohms I just checked !!! RS210 and RS212
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  9. Both heads you mention are also 4ohm min - are you 100% positive the cabs are each 4ohm?

    I can't tell you for sure about the fan but if I had to guess it should be always on. I actually just had a failure of my Shuttle 9 head's fan at the last gig and from what I've seen for that amp the fan should always be on.

    Edit: I see your reply about the cab ohms - that makes more sense! Likely the fan is the issue.
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  10. Inara

    Inara Fierce Fun Fretless Female

    Jun 12, 2017
    Seattle, WA USA
    I have an RH450 and just checked: my fan doesn't run all the time. I think it's probably thermally managed, only running when needed. One thing to try is to use a patch cable to connect the effects loop ... The jacks for effects out and in can get dirty, and are known to cause cutting out on many amps. So just take a short cable if you have one, or an instrument cable, and connect the two jacks marked number 6 and 7 (Insert pre/amp I/O) in the image I'll attach, and see if that helps.
    Last edited: Sep 9, 2021
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  11. Wicked G

    Wicked G

    Jan 19, 2017
    Hell Paso Texas
    Agree with @Inara. The fan is not always on and as you have noticed the RS cabs are 8 ohms. The RH450 can actually run 3 RS cabs as per their website and maybe the manual.

    Your amp also has a headphone jack and it would not hurt to run a plug through it a couple times as that also can cause intermittent cut outs on most if not all amps.

    If that doesn't help you could always do a factory reset where you can simply power on the amp while simultaneously holding all three preset buttons. Hopefully one of those 3 suggestions should square you away.
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  12. Howard Page

    Howard Page

    Sep 9, 2021
    Thanks everyone, great advice about the other sockets - I'll check them out whilst I've got the cover off. I'll then reassemble it and run the amp for a while in a clear plastic bag to get the heat up and see if the overheating warning 'H' comes up......
  13. You're certainly not the first person to describe that problem.

    Without taking it to a tech with proper diagnosis abilities, I highly doubt the effects loop is the problem. Some RH450s could be twitchy on noisy line power, but it was only a small number of them. There's fairly tight integration between the amp and the power supply and TC can plug in and read fault-codes just like a car.

    I recommend contact Music Tribe/TC Electronic and see what they say.
  14. I have a RH450. I think you were asking too much of the amp, it's only 236 watts.
    In my experience, the taper on the volume pot is pretty much maxed at 4-5 on the volume knob. Anything beyond that and there is nothing left in the tank.
    If you have more gigs outdoors where you will be driving the amp hard, I would considering looking at a bigger amp to meet your volume needs.
  15. john m

    john m Supporting Member

    Jan 15, 2006
    “Daisy chained” usually results in parallel connections unless a special cable has been created.
  16. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Don’t run the amp without the cover, it’s an essential part of the cooling system. It is part of what defines how the air flows through the amp.

    This is true of many (not all) amps.
  17. sawzalot

    sawzalot Supporting Member

    Oct 18, 2007
    The RH450 can run with up to three RS series cabinets. I run my RS750 with an RS210 + a RS212 all the time.

    From the RH450 manual:

    "Cabinets or combinations of cabinets must load the amplifier with a minimum of 4 Ohm. A maximum of three RS cabinets can be used or two 8 Ohm cabinets of any other brand. If e.g. the speaker output is loaded with only 2 Ohm or less and you drive the RH450 at very high volumes over a long period of time, the amplifier enters Heat Protection mode."
  18. Howard Page

    Howard Page

    Sep 9, 2021
    Thanks guys. To recap I have two 8 ohm cabs, a RS2x10 and a RS2x12 - the amp was run with the volume at 12 O'clock so half volume. It was in a very large barn so not unduly hot. I'm disappointed if the amp can't run at half volume for more than half an hour but my plan was to see how I like the TC head (I love it) with a view to getting a RH750 and using teh 450 as backup. I still intend to do this. I replaced the fan and will try and soak test the amp and watch for the overheating warning.
    Thanks everyone for your support! :cool:
  19. Numbers on the volume knob mean nothing. i can tell you from experience, that half way on the knob is pretty much maxing the output of the amp. The RH750 would probably meet your needs. Remember, 236 watts.
  20. Yeah but those amps have so much protection that I really, really doubt he killed it by running it too loud. That's just not how those amps work. You should be able to run them at 11 all day and the RH450 might get a bit warm, but it won't blow up or fail because of it.