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Old 12th May 2009, 08:33 PM   #1
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Question 7695...useful audio tube??

I got my hands on a new pair of 7695s...look like a power pentode. Any potential in a Class A amp ? Or any other ideas ??
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Old 13th May 2009, 09:37 AM   #2
Arnulf is offline Arnulf  Europe
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Interesting tube, at least according to the datasheet. You could use that very high heater voltage and rather low anode voltage to your advantage (= no heater transformer/winding required if you hook up heaters in series and add a power resistor or CCS to the chain to drop those extra ~5W).

They also have rather low Zout (1100R). This can be a plus (OTL would be an option if you had more of these) and a downside if you already own output transformers that you want to use with these tubes and they don't allow for suitably (low) transformation ratios.
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Old 13th May 2009, 10:29 AM   #3
SY is offline SY  United States
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Triode connected, you should be able to get 5-7W in push-pull. This would be a good candidate for AB2 or screen-drive, where you could get closer to 10W. The attractive feature is the low load impedance requirement, making the output transformer a much easier proposition.
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Old 13th May 2009, 10:56 AM   #4
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Ok...thanks SY...how would I achieve the 50V filaments?
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Old 13th May 2009, 11:05 AM   #5
SY is offline SY  United States
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A transformer might work.

I'd probably series them, add series resistors, and use an isolation transformer.
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Old 5th May 2013, 11:32 PM   #6
srinath is offline srinath  United States
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I have an amp with that output tube set that came form zenith console.
So I have no input trafo - I need to get one to have it live out in its own chassis, but I thought my amp was Single ended.
Is there a way to put bigger output transformers and get more power out of it.

5-7 watts may be OK ... but something like 20 would be great.

Cool.
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