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Old 31st Jan 2006, 1:18 am   #2
paulsherwin
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Join Date: Jun 2003
Location: Oxford, UK
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Default Re: Ultra Coronation Twin - What on earth is this?

I think you should be very careful with this set. It has fairly obviously been Got At, possibly a very long time ago.

The wirewound pot doesn't look original from your photo, and the DL96 in the photo is wrong - it has the wrong heater current. Possibly somebody has replaced all the valves with Dx96 types and modified the dropper arrangements accordingly, but you will need to check everything out. There is no problem replacing Mazda types with equivalents but the Dx96 series *aren't* equivalents

The resistor values aren't as critical as you seem to think. Generally, going to the next larger preferred value will be OK. Check the circuit carefully to work out the power handling required by the different resistors. You can combine resistors in series or parallel to get the values you need if necessary.

For info on valve equivalents, the first thing you should do is download the free TDSL-PE database from the Duncans Amps website: http://www.duncanamps.com/tdslpe/index.html. I use it all the time. It's not so good with Mazda types though. The correct Mullard valves for your set are DK92, DF91, DAF91, DL94.

Good luck with this - it looks like quite a job for a beginner.

Best regards, Paul

Last edited by paulsherwin; 31st Jan 2006 at 1:42 am.
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