stevie Posted March 27, 2011 Share Posted March 27, 2011 What is the lowest impedance the TC Electronic 450 amp can handle? I know what the official line is, but has TC actually explained why the amp is OK with 3 of their 8-ohm cabs? Quote Link to comment Share on other sites More sharing options...
Platypus Posted March 27, 2011 Share Posted March 27, 2011 The stated impedance is 4 Ohm - however, TC Electronic they say they are confident that you can connect 3 of THEIR 8 Ohm cabs Because the impedance of other manufacturers cab can vary from the published, they don't recommend doing that with any other make of cab. [quote name='stevie' post='1178909' date='Mar 27 2011, 10:29 PM']What is the lowest impedance the TC Electronic 450 amp can handle? I know what the official line is, but has TC actually explained why the amp is OK with 3 of their 8-ohm cabs?[/quote] Quote Link to comment Share on other sites More sharing options...
icastle Posted March 27, 2011 Share Posted March 27, 2011 [quote name='stevie' post='1178909' date='Mar 27 2011, 10:29 PM']What is the lowest impedance the TC Electronic 450 amp can handle? I know what the official line is, but has TC actually explained why the amp is OK with 3 of their 8-ohm cabs?[/quote] They are a bit vague aren't they? As they're only using 2P Speakons I can only guess that using the loop outs on the back of the TC cabs puts a whapping great resistor in line to bring the impedance back up. Quote Link to comment Share on other sites More sharing options...
stevie Posted March 27, 2011 Author Share Posted March 27, 2011 [quote name='Platypus' post='1178927' date='Mar 27 2011, 10:41 PM']The stated impedance is 4 Ohm - however, TC Electronic they say they are confident that you can connect 3 of THEIR 8 Ohm cabs[/quote] That's the official line. It doesn't make much sense, does it? Quote Link to comment Share on other sites More sharing options...
stevie Posted March 27, 2011 Author Share Posted March 27, 2011 (edited) [quote name='icastle' post='1178936' date='Mar 27 2011, 10:47 PM']They are a bit vague aren't they? As they're only using 2P Speakons I can only guess that using the loop outs on the back of the TC cabs puts a whapping great resistor in line to bring the impedance back up.[/quote] They are definitely not being straight here. I've just got myself a 450 Classic and it only has one Speakon out. Even if they had put a resistor in line (I assume you're joking) it would be in line with everybody's cabinets - not just TC's own. So, will it handle a 2.7 ohm load, or are TC cabs not 8-ohms? Or is TC not saying? By the way, I'm not asking out of idle curiosity. I'd like to use a 4-ohm and 8-ohm cab together. Edited March 27, 2011 by stevie Quote Link to comment Share on other sites More sharing options...
icastle Posted March 27, 2011 Share Posted March 27, 2011 (edited) [quote name='stevie' post='1178961' date='Mar 27 2011, 11:07 PM']They are definitely not being specific. I've just got myself a 450 Classic and it only has one Speakon out. Even if they had put a resistor in line (I assume you're joking) it would be in line with everybody's cabinets - not just TC's own. So, will it handle a 2.7 ohm load, or are TC cabs not 8-ohms? Or is TC not saying?[/quote] No I meant inside the TC cab itself, not the head. It wouldn't necessarily be something as crude as I described - could be a xover of some description - anything to just raise the impedance on the loop out socket by a couple of ohms. EDIT: As you're looking for a definitive answer to base a purchase on, the best thing to do would be to ask TC and get it 'direct from the horses mouth'. Edited March 27, 2011 by icastle Quote Link to comment Share on other sites More sharing options...
stevie Posted March 27, 2011 Author Share Posted March 27, 2011 [quote name='icastle' post='1178978' date='Mar 27 2011, 11:21 PM']No I meant inside the TC cab itself, not the head. It wouldn't necessarily be something as crude as I described - could be a xover of some description - anything to just raise the impedance on the loop out socket by a couple of ohms.[/quote] I see what you mean. They might have an inductor on the bass drivers that would raise the impedance a bit above nominal, but it wouldn't raise it by a couple of ohms. [quote name='icastle' post='1178978' date='Mar 27 2011, 11:21 PM']EDIT: As you're looking for a definitive answer to base a purchase on, the best thing to do would be to ask TC and get it 'direct from the horses mouth'.[/quote] Not a bad idea, although I've already made the purchase. Quote Link to comment Share on other sites More sharing options...
MythSte Posted March 27, 2011 Share Posted March 27, 2011 [quote name='stevie' post='1178990' date='Mar 27 2011, 11:36 PM']I see what you mean. They might have an inductor on the bass drivers that would raise the impedance a bit above nominal, but it wouldn't raise it by a couple of ohms. Not a bad idea, although I've already made the purchase.[/quote] I would imagine that they're suggesting that TC cabs that are rated at 8 ohms are actually measuring 8 or above, and that other manufacturers may be below. It makes sense that they are covering themselves with a sort of margin for error with regards to other cabs. Quote Link to comment Share on other sites More sharing options...
markstuk Posted March 28, 2011 Share Posted March 28, 2011 The manual for the RH450 states something along these lines... "If you use loads of 2 ohms or less at very high volumes over a long period of time the heat protection circuitry will cut in and shut the amp down".. Quote Link to comment Share on other sites More sharing options...
markstuk Posted March 28, 2011 Share Posted March 28, 2011 Just tried my RH450 into a nominal 2 ohms (2 x EBS Proline 410) .. Apart from my daughter slamming shut every door in the house, no obvious negative effects... Quote Link to comment Share on other sites More sharing options...
alexclaber Posted March 28, 2011 Share Posted March 28, 2011 My guess is that it has good protection circuitry and they've proven that you can't damage it driving three of their cabs. Lots of amps will run loads below their rated minimum without a problem. I'd be surprised if it has issues driving any other three 8 ohm nominal cabs, but conveniently for their sales they're not guaranteeing it for anything but their own cabs. I'd be astounded if there's anything clever going on with internal circuitry in the cabs, especially having poked around in them. Quote Link to comment Share on other sites More sharing options...
chris_b Posted March 28, 2011 Share Posted March 28, 2011 TC would kill the competition if they uprated their cooling system and officially rated their amps at 2 ohm min. They'd clean up. Quote Link to comment Share on other sites More sharing options...
alexclaber Posted March 28, 2011 Share Posted March 28, 2011 (edited) The problem with selling an amp that is rated down to 2 ohms is that you'll sell fewer to people with 8 and 4 ohm cabs because so many are convinced that they need to get full power from their amp. Marketing psychology! Edited March 28, 2011 by alexclaber Quote Link to comment Share on other sites More sharing options...
markstuk Posted March 28, 2011 Share Posted March 28, 2011 Alex, You should be finishing my S12T not gabbing on here Cheers Mark Quote Link to comment Share on other sites More sharing options...
Dood Posted March 29, 2011 Share Posted March 29, 2011 [quote name='MythSte' post='1178998' date='Mar 27 2011, 11:41 PM']I would imagine that they're suggesting that TC cabs that are rated at 8 ohms are actually measuring 8 or above, and that other manufacturers may be below. It makes sense that they are covering themselves with a sort of margin for error with regards to other cabs.[/quote] That's kinda what I had in mind - if each individual TC speaker manufactured was only say half an ohm higher, then multiples of the cabinets would present a high enough load not to fry the amp - whereas, as Ste as rightly pointed out, there is no way of being sure that another manufacturer hasn't been less than accurate with their own ratings. Quote Link to comment Share on other sites More sharing options...
alexclaber Posted March 29, 2011 Share Posted March 29, 2011 The ratings are only nominal, just a guideline to help with amp matching. The actual impedance varies hugely across the frequency spectrum. Nominal impedance ratings are inaccurate by definition. Quote Link to comment Share on other sites More sharing options...
markstuk Posted March 29, 2011 Share Posted March 29, 2011 +111 Quote Link to comment Share on other sites More sharing options...
stevie Posted April 2, 2011 Author Share Posted April 2, 2011 Thanks for all the input on this topic. It does look like the TC 450 has been designed to handle a sensible 2.7-ohm load, especially given Mark's reassuring comments. I'll proceed on that basis. It would be interesting to see some independent measurements on this amp, although I think that means waiting until Bass Gear Magazine publishes a review. Quote Link to comment Share on other sites More sharing options...
mcnach Posted April 2, 2011 Share Posted April 2, 2011 [quote name='stevie' post='1178909' date='Mar 27 2011, 10:29 PM']What is the lowest impedance the TC Electronic 450 amp can handle? I know what the official line is, but has TC actually explained why the amp is OK with 3 of their 8-ohm cabs?[/quote] yes they did explain, extensively. It's all in their website, and very educational read it is too... Quote Link to comment Share on other sites More sharing options...
mcnach Posted April 2, 2011 Share Posted April 2, 2011 [quote name='alexclaber' post='1180981' date='Mar 29 2011, 04:23 PM']The ratings are only nominal, just a guideline to help with amp matching. The actual impedance varies hugely across the frequency spectrum. Nominal impedance ratings are inaccurate by definition.[/quote] and THIS is in essence what the info in their website says. Because they designed the amp, and they know the behaviour of their speakers, they are confident that they work well together up to 3 cabs per amplifier. Other brands may work... but they have not tested them so therefore they cannot/won't recommend them. Quote Link to comment Share on other sites More sharing options...
markstuk Posted April 7, 2011 Share Posted April 7, 2011 In the interests of scientific research I ran my RH450 into 2 x EBS Proline cabs (2 Ohms) for about three hours last night at rehearsal.. Although I never went above 3 on the master (quite loud enough thank you) the amp stayed as cool as normal with no shutting down... I don't intend to do this regularily but it seems stable into a nominal 2 ohms... I don't recommend that anyone else try this however, I was happy to trust in the protection circuitry, however this is out of spec... Cheers Mark [quote name='mcnach' post='1186148' date='Apr 2 2011, 08:14 PM']and THIS is in essence what the info in their website says. Because they designed the amp, and they know the behaviour of their speakers, they are confident that they work well together up to 3 cabs per amplifier. Other brands may work... but they have not tested them so therefore they cannot/won't recommend them.[/quote] Quote Link to comment Share on other sites More sharing options...
stevie Posted April 7, 2011 Author Share Posted April 7, 2011 Much appreciated. I'm sure the facts will come out eventually, but that's very useful information - to be used with care, of course. Quote Link to comment Share on other sites More sharing options...
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