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RH 750


Phantomnin
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[quote name='markstuk' post='1248927' date='May 29 2011, 09:32 AM']Except that the specs say "Universal 100-240V~ 50/60 Hz (100 W @ 1/8 Power)"[/quote]
Exactly, So did the Mesa Boogie ones[b] for the UK model[/b] and exactly how the buyer and others have been caught out with other brands too hence why it keeps popping up. Like I said the TC may well be fine my Genz is for example but I cant stress that not all makes are even though the pics show the little red switch etc which is fine until the US one arrives with a blanking plate because it is not there! Expensive mistake made by many trust me.

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[quote name='~tl' post='1248948' date='May 29 2011, 09:55 AM']Not quite correct, but you've got the idea. It's the ratio of windings in the primary and secondary of the transformer that are important rather than the actual number of windings (of which there will be hundreds). So to get 12V from 240V then you need a transformer with a ratio of 20:1, i.e. twenty times more windings in the primary than the secondary. Likewise for 120V to 12V you need a 10:1 ratio transformer. By putting a "tap" (i.e. another connection point) half way through the 20:1 transformer coil, you get the option of a 10:1 coil as well.

"Class D" amplifiers, like the RH750 will often use a switched-mode supply, which is a whole other bag of tricks. So this discussion is purely academic in this context.[/quote]

Thats why I said [i]simplified[/i] and also said to factor in that in reality hundreds or thousands of windings :) And like I said before class D will[i] probably [/i]be fine but I keep seeing both threads with wise buyers trying to save a fortune by shipping them in and then another thread saying has anyone got a stepup transformer that weighs less than a house and costs less than £500?

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Two quick points from me:

I've used a TC RH head purchased in the US and it was absolutely fine over here, no problems with power whatsoever.

Prices on RH450's are way down in the States now - you can pick up a new one for $569 if you shop around. The heavy discounters don't have the RH750 yet but I'd guess they will come in closer to $800 than $1,000.

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[quote name='molan' post='1248987' date='May 29 2011, 11:00 AM']Two quick points from me:

I've used a TC RH head purchased in the US and it was absolutely fine over here, no problems with power whatsoever.[/quote]

Nice one that clears up the TC then and its fine as I thought it would be but even if a few people have read about the woes of importing any electrical goods and understood it then thats good and what forums are all about :)

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Except there is no red switch on the back of the RH...

It's good to be cautious but worth doing some fact checking as well..

[quote name='stingrayPete1977' post='1248949' date='May 29 2011, 09:57 AM']Exactly, So did the Mesa Boogie ones[b] for the UK model[/b] and exactly how the buyer and others have been caught out with other brands too hence why it keeps popping up. Like I said the TC may well be fine my Genz is for example but I cant stress that not all makes are even though the pics show the little red switch etc which is fine until the US one arrives with a blanking plate because it is not there! Expensive mistake made by many trust me.[/quote]

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"If the SMPS has an AC input, then the first stage is to convert the input to DC. This is called rectification. The rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically. This is a feature of larger supplies to permit operation from nominally 120 V or 240 V supplies."

I think this is probably a common feature of switched mode power supplies...



[quote name='stingrayPete1977' post='1249285' date='May 29 2011, 03:25 PM']Clever beggers at TC aint they, I wonder whats inside? :)[/quote]

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Who are the heavy discounters in the states and will they ship to the UK?

[quote name='molan' post='1248987' date='May 29 2011, 11:00 AM']Two quick points from me:

I've used a TC RH head purchased in the US and it was absolutely fine over here, no problems with power whatsoever.

Prices on RH450's are way down in the States now - you can pick up a new one for $569 if you shop around. The heavy discounters don't have the RH750 yet but I'd guess they will come in closer to $800 than $1,000.[/quote]

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Automatic switching is quite clever to be fair to TC as the Genz is manual on the back and some others have to be opened up to be switched over so fair play to TC unless there is an argument from the others for it being another part that can fail that 99% of us will never use unless you take you amp to a 120v country?

Sorry if its gone a bit OT and it looks like most class D amps (If not all?) have a switch mode power supply that can be switched between voltages easily which will probably just add fuel to the fire next time someone buys another piece of gear and says well their amp can run on either and it says in the UK spec list that it can so it must be able to. Your post highlighted the problem perfectly when you said what the specs were markstuk because thats exactly what some Mesa boogie buyers had done! Costly fail :)

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Sure, not arguing about this :-)

But bear in mind TC are a danish company who are aware there is a rest of the world with different plugs/voltage/Hz AC power rather than a US company continuously surprised that there is an outside world, and that it's not all like California :-)


[quote name='stingrayPete1977' post='1250011' date='May 30 2011, 10:46 AM']Automatic switching is quite clever to be fair to TC as the Genz is manual on the back and some others have to be opened up to be switched over so fair play to TC unless there is an argument from the others for it being another part that can fail that 99% of us will never use unless you take you amp to a 120v country?

Sorry if its gone a bit OT and it looks like most class D amps (If not all?) have a switch mode power supply that can be switched between voltages easily which will probably just add fuel to the fire next time someone buys another piece of gear and says well their amp can run on either and it says in the UK spec list that it can so it must be able to. Your post highlighted the problem perfectly when you said what the specs were markstuk because thats exactly what some Mesa boogie buyers had done! Costly fail :)[/quote]

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[quote name='molan' post='1248987' date='May 29 2011, 10:00 AM']I've used a TC RH head purchased in the US and it was absolutely fine over here, no problems with power whatsoever.[/quote]

Ditto, I have a UK sourced RH450 and a US sourced RH450 and there was never any question of it not working. TC globally advertise the autosensing power supply as a product feature.

The biggest potential savings are if you go to the US and so can avoid international shipping (legal) and import tax/duties (not legal). The boxed item is big, but if I were wanting to bring one back, I'd discard the packaging and simply bring back the amp (don't even bother with the US mains lead!). That easily fits in a laptop bag with room to spare, or in your case - easy...

And, while the real discounters, like Proaudiostar who sold me my RH450, aren't yet selling the RH750, when they do, you could make a whole stack of savings.

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[quote name='owen' post='1251654' date='May 31 2011, 03:42 PM']So, this 'only driving down to 2 ohms' with TC cabs. Do TC cabs have special magic in them, or is it just marketing? This and a couple of 4 ohm 1x12" cabs would totally float my boat.[/quote]

Its because TC know the exact impedance of their cabinets, whereas they dont for other manufacturers.

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I am far from complete in my knowledege in this field, but I was under the impression that impedance ratings are nominal at best with all sorts of issues affecting what the amp actually 'sees'. Do TC actually do anything clever to their cabs?

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[quote name='Musicman20' post='1248850' date='May 29 2011, 02:23 AM']www.bassmerchant.com

Darren will match UK prices. (edit)[/quote]
I decided to order over here from bassmerchant, thanks to Musicman20 for the recommendation :)

Went for the RS210C & the RH750, just have to wait a couple of weeks now for them to come in :lol: :)

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[quote name='sgh' post='1251795' date='May 31 2011, 05:22 PM']I decided to order over here from bassmerchant, thanks to Musicman20 for the recommendation :)

Went for the RS210C & the RH750, just have to wait a couple of weeks now for them to come in :D :)[/quote]

No problem :lol: Always happy to recommend after Ive had such great service from those guys.

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  • 4 weeks later...

[quote name='sgh' post='1280145' date='Jun 23 2011, 08:50 PM']Just got my RH750 & RS210 today and am mighterly impressed :)
Just checking re voltages, I could take my UK bought 750 to the US & just use the uk lead & a 3 pin to 2 pin plug adapter ?[/quote]

Yep!

It switches power itself.

Im still waiting for my 3rd RH750...the 2nd had a really odd vibrating when the fan was on that stopped and started when you touched the top of the amp....tried all surfaces, tried it on its side, listened through the vents and hey presto, something was vibrating on catching. Shame.

Hopefully 3rd time lucky.

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[quote name='Musicman20' post='1280271' date='Jun 23 2011, 10:20 PM']Yep!

It switches power itself.

Im still waiting for my 3rd RH750...the 2nd had a really odd vibrating when the fan was on that stopped and started when you touched the top of the amp....tried all surfaces, tried it on its side, listened through the vents and hey presto, something was vibrating on catching. Shame.

Hopefully 3rd time lucky.[/quote]
Best of luck with your replacement.

I should be ok taking this through as hand luggage ?

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