I bought a German amp and now have a voltage/cycles issue.

[rhythmrocker]

I bought a used Hughes and Kettner CF-200, single-space, solid state power amp (2x100watts stereo/ 1x200 mono+bridged).

I read somewhere that it had a voltage converter on the back and in fact it does > it converts from 240 volts to 220 volts.

Ok - I was wrong being that I thought it would convert to US 110/120 volts.

So I have a 220/240 volt unit that operates at a frequency of 50 cycles.
here, we do 110/120 at 60 cycles.

I know a step up transformer will address the voltage. But what about the frequency?

Is there likely a transformer change that can be made inside the amp to make it work here in the US voltage-wise? Are there many parts inside a solid state amp that will need to be changed out to operate at 50 cycles?

Note: I'm waiting on a few emails from techs who might know - may take a few days; contacting H&K is another option, but this unit has been discontinued for 20 years.

Your advise is appreciated.

[hdhoo73]

Maybe this will help:

http://www.gearslutz.com/board/geekslutz-forum/126187-convert-50hz-60hz.html

[rhythmrocker]

Maybe this will help:

http://www.gearslutz.com/board/geekslutz-forum/126187-convert-50hz-60hz.html

I saw that - but don't want to be concerned about doing a "feel test." Good information though.

Other ideas?

[SatelliteAmps]

I don't think you have anything to worry about. Running that amp under 50Hz or 60Hz is not going to be terribly different, nor should it affect the performance of the amplifier.

[rhythmrocker]

Thanks Adam, you're always helpful.

[donnyjaguar]

50Hz design being run at 60Hz isn't the problem, its if you want to go the other way you can run into overheated power transformers. As for the voltage, I would dismantle the amplifier and see how the primary of the power transformer is configured. It could already have provisions for 120Vac use. If not, you are probably looking at, worst case, a replacement power transformer, fuse, and pilot light & MOV if so equipped. A 200Watt amplifier needs a $ub$tantial transformer of the correct voltages and current ratings.

If the secondary of the power transformer is a simple 3-wire job using a full-wave bridge to supply both + and - rails, you may be able to convert it to a voltage-doubler and use the stock transformer pumping 120Vac into the 220Vac winding. This could require replacement of the diode bridge (maybe not) and increasing the capacity of the filter capacitors (maybe not). Its certainly a lower cost option and one I'd explore first. :) The reality is that it will likely reduce maximum output power somewhat as you will in essence be adding series resistance to the power supply limiting maximum current. For my style of playing it probably wouldn't make any difference.

[rhythmrocker]

50Hz design being run at 60Hz isn't the problem, its if you want to go the other way you can run into overheated power transformers. As for the voltage, I would dismantle the amplifier and see how the primary of the power transformer is configured. It could already have provisions for 120Vac use. If not, you are probably looking at, worst case, a replacement power transformer, fuse, and pilot light & MOV if so equipped. A 200Watt amplifier needs a $ub$tantial transformer of the correct voltages and current ratings.

If the secondary of the power transformer is a simple 3-wire job using a full-wave bridge to supply both + and - rails, you may be able to convert it to a voltage-doubler and use the stock transformer pumping 120Vac into the 220Vac winding. This could require replacement of the diode bridge (maybe not) and increasing the capacity of the filter capacitors (maybe not). Its certainly a lower cost option and one I'd explore first. :) The reality is that it will likely reduce maximum output power somewhat as you will in essence be adding series resistance to the power supply limiting maximum current. For my style of playing it probably wouldn't make any difference.

More good information - thank you! I am going to get the amp over to Val King, he's local and an H&K Authorized service/repair guy. Thanks all once again!

[rhythmrocker]

A follow-up: Val King found an OT that will work and will have to do a little engineering to make sure the unit works as it should. Note that I didn't want to use an outboard unit as they are about 4-5" square and can change the tone.

[donnyjaguar]

Did you show them my post? :) They are going with the least-effort, and greatest cost to customer, solution. I think you meant power transformer.

[rhythmrocker]

Did you show them my post? :) They are going with the least-effort, and greatest cost to customer, solution. I think you meant power transformer.

Hey - I did not show Val your post BUT since I read your post, when Val said that he would look for 120VAC provisions on the existing POWER transformer (yes, I made a booo-boo before), I knew what he was talking about.

Anyways, I don't know about the "least-effort, and greatest cost to customer, solution" since I don't know electronics. So, like most, even after doing research, I have to take what I can. Val King stated on the phone to me in no uncertain terms that any engineering necessary would be in the 1.7 - 2.0 time range and that he would check out the entire unit and run it all day to make sure that it is ok. He stated that he had to because his reputation was "on the line." Sounded fair enough!

[donnyjaguar]

Running a voltage doubler on a power amplifier isn't bleeding edge stuff prone to premature failure. In fact I know of one very famous amplifier that does it this way right from the factory.

Anyway, I leave it with you. :)