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brianboru 10th February 2004 10:21 AM

Convert Krell 300iL to European voltage
I've never opened an amplifier before in my life but am always game for toying with a few electronics. However I really do not want to blow my Krell 300iL amp and was wondering if anyone out there could advise me on how to convert this amp from 110 to 230V (basically American to UK voltage). Is it easy? Or should I pay up the 150 my "friendly" dealer is charging? Help!!
Any info is much appreciated!


5th element 10th February 2004 06:19 PM

Its my guess that the traffo is made specifically for the krell so may not have dual primaries. However if it does, then usually for 110 voltage areas the primaries are wired in parallel and in 240 voltage areas in series. So if the amp is spec'd for a 110 area, if you locate the primaries and they are in parallel then wiring them up in series should sort it. However, this is an expensive piece of kit and not worth destroying just by simply plugging the unit into 240 thinking you have sorted it.

If you are going to try this then get another transformer and step down the 240 to something like 20 volts then connect the amp to that as it is, ie wired for 110. Then measure the voltage off one of the secondaries. Wire the traffo for 240, ie in series, then connect it again to the 20v transformer and see if the voltage halves, if it does then you are OK. BUT please make sure that there is no other circuitary connected to the mains input appart from the main transformer otherwise you could blow other bits too.

If you do try this and it fails you cant hold me responsible:D


brianboru 10th February 2004 07:16 PM

ho ho ho - unfortunately our physics teacher at school wasn't too hot and that went way over my head :eek:!! I was hoping it was case of flicking a few switches! many thanks for your help though...

lucpes 11th February 2004 08:10 AM

150 pounds is waaay too much. It has an 800VA transformer, so a new toroid transformer would cost considerably less than that. You might want to tell the dealer that :) Looks like he's charging 100 pounds for the work and 50 for parts... Then again, it depends if the amp was new, how much the amp 'retailed' for and if you want it done fast or you can wait. Is it covered by warranty (is the 'dealer' authorized?). If not you can tell him to kiss 150 pounds goodbye.

Take a read here, it will bring you up to date with amplifier supplies:


power supplies:

Then again, if you haven't tinkered with these before you might ruin it so you must pay the bills :) Also, this is an integrated amp and it might have separate trafos for pre and final stages...

A quick&ugly&cheap sollution would be to buy a 1kVA rated 240-110 converter/transformer and feed the Krell through it, in order not to ruin the warranty. Make sure that you don't put the trafo asswards though :)

The BEST sollution would be getting a service manual and check for this issue in there.

Tube_Dude 11th February 2004 08:15 AM


Originally posted by brianboru
ho ho ho - unfortunately our physics teacher at school wasn't too hot and that went way over my head :eek:!! I was hoping it was case of flicking a few switches! many thanks for your help though...

I have a Krell KST 100 and the change of voltage from 110 to 230volts done flicking two switches!!
Have you open the case for trying to see if there are this switches?
In mine they are black and red!!

PS: The change must be done with amp disconnected!!:att'n:

brianboru 11th February 2004 09:02 AM

many thanks for the additional helpful comments. the amp is totally brand new - i bought it in america from a dealer who helpfully ships to the UK but doesn't do the voltage conversion. As the dollar is so weak I thought now was the time to treat myself..

I haven't opened up the box yet - i'm waiting for another dealer to get back to me with a quote. I don't want to mess with it quite yet but if I get more absurd quotes from dealers then it will be time to delve in and blow some expensive gear! I'm hoping that it will be a case of flicking a few switches as in Jorge's amp - we shall see.

Audiofanatic 11th February 2004 01:07 PM

Krell AGAIN!
Hi guys,

Krell does it again! I have a friend that had the same problem.
He was afraid that he would blow the whole amp if he did it himself.
Well It's verry simple in almost all KRELL's you have two switches.
Both have a text on it. 120 -in the first possition 240 in the other possition or 1 - 2 . So if it is set to 1 it'll work on 120 volts in possition 2 it'll work in 240 volts.

That's It! If it's with wires or jumpers (I don't think so) than look for a SERVICE MANUAL!

All the best and please let us know if you succeed!

Best regards,

Audiofanatic ;)

brianboru 11th February 2004 01:31 PM

Wow! That doesn't sound too hard... certainly doesn't sound like 150 of labour!! Will let you all know how i get on...

Thanks everyone!

brianboru 26th February 2004 12:33 PM

Hello everyone,

Well I just got round to opening it up and there are 3 switches inside... each labeled SW1, SW2 and SW3. They are set at 2,1,2 respectively which at the mo is US voltage (60hz, 120V). I've emailed Krell and asked them for the appropiate combo - I doubt they will send them to me but worth a try. Also, do I want 220V or 240V for UK??

brianboru 26th February 2004 12:45 PM

One further point...

I just phoned up Absolute Sounds again and asked them for the combination. They told me that it now costs 550 ~ $1000 to do the conversion because there is a microprocessor running at 60hz in there that needs to be converted to 50hz. This sounds to me like absolute codswallop. I think their business must be getting hurt from people importing from the US on the back of the weak dollar.

I just hope Krell email the combo....!

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