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exurbia 10th April 2005 07:10 AM

cinema amps
Help please,

I have inherited 3 large cinema amps, they use 4x kt66 per channel.
If any one can help me identify the output trafos it will help me a lot. The trafos are made by ferguson and have the number OP527 on them. What i need is the connection diagram for the taps. At the moment they are set for 100volt output.
The amps were made by National in 1970, possibly in Sydney.
Photos to follow.

rpapps 10th April 2005 07:20 AM

You could try their new owners.
They may have some archival information.

Good luck

exurbia 10th April 2005 07:25 AM

2 Attachment(s)
photos of amps as i picked them up. All of the kt 66's had been smashed.

exurbia 10th April 2005 07:26 AM

national amp
2 Attachment(s)
photo 2

exurbia 10th April 2005 07:30 AM

2 Attachment(s)
photo 3

audiousername 10th April 2005 08:27 AM

All I could dig up was this data on Ferguson Transformers' "medium fidelity" range, which clearly isn't what these cinema amps have.

A shame about the KT66s... The sight of those smashed valves breaks my heart :sad:

You could probably determine most of the leadouts of the transformers by having a look at how they're hooked up in the amp right now. The impedance ratio can be determined from the square of the turns raio - which can be found by applying a known AC voltage to the primary, and measuring the resultant voltage on the secondary (or vice versa).

Tekko 10th April 2005 08:48 AM

Try a search for the amps brand and model number if you havent already tried that. Take a pic of the underside of the amps too.

exurbia 10th April 2005 09:27 AM

cinema amps
For what its worth (f**k all) the kt66's were brand new as the owner had just had the amps serviced, before closing the cinema. I managed to find four brand new ones in boxes that had not been smashed. These are now for sale as i have no use for them.

audiousername 10th April 2005 12:32 PM

Re: cinema amps

Originally posted by exurbia
the owner had just had the amps serviced
Oh. So then they should probably be working once they get new valves, yeah?


Originally posted by exurbia
I managed to find four brand new ones in boxes that had not been smashed. These are now for sale as i have no use for them.
Not going to use them in one of the cinema amps?

btw, how much?

exurbia 10th April 2005 02:35 PM

cinema amps
The kt's are of no use to me as finding another eight is too hard. My son wants to re valve using either 6l6 or 807 as they are easy to source. According to my Rider master handbook the 6l6 will sub with no adjustments. Is this correct ? I want to have a listen before i sell the amps or swap them. Personally i find the size and weight of these amps to be inconvenient. They weigh about 40 kilos each. A friend up here has suggested using two 4-125a's in pp per amp rather than a quad of kt66 etc. The power trafos are really big and have 2 secondarys one of 600 0 600, 260 0 260 a 50v bias tap and a very big 6.3 volt supply at least 12 amps according to what was being run, including the pre amp supply. Unfortunately the cabinet was damaged beyond repair, although i'm sure my other half wouldn't have let me keep it. Each amp has a balancing trafo for input and the pre is also balanced.

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