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Old 6th October 2006, 01:11 AM   #21
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Heres something else to think about. How big of a choke and capacitor do you need to properly filter out 100hz ripple. Now how big for 1Mhz ripple? Even at 100khz not much noise is going to get through an output transformer with a bandwidth that goes to 50khz if you're lucky.
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Old 6th October 2006, 05:41 AM   #22
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I guess with an OTL design, there will be no output transformer, the situation will be a bit different?? Yes? No?
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Old 6th October 2006, 06:28 AM   #23
ssanmor is offline ssanmor  Spain
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Ackcheng,
The ss state amplifier we tested on was a LM3886 based amplifier (bridge-parallel mode). Hope this helps.
I know that some of our customers are also testing it with ss amplifiers, mainly their own designs, sorry don't have more details about them.
The SPS80 topology is a half-bridge converter.

Best regards,
Sergio
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Old 6th October 2006, 06:56 AM   #24
peufeu is offline peufeu  France
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You could make a tube class D amp...
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Old 6th October 2006, 07:01 AM   #25
ssanmor is offline ssanmor  Spain
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Class-D amps require very deep knowledge of the devices you are using to get optimal results. I don't consider myself prepared to develop a Class-D amp based on tubes, if that makes any sense or is possible at all, but thanks for the suggestion.
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Old 14th November 2006, 11:59 AM   #26
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I have finally bought 2 SPS80HV for my OTL and did a few test on it.

But first, here are some pic for the 500W linear power supply with 5400uF filtering cap

This picture shows the voltage output of the linear power supply (LPS) when there is no signal input to the OTL amp. B+ voltage measured as 161.5Vwith 0.4V rippleˇAcurrent is 0.3AˇC
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File Type: jpg fig1.jpg (85.1 KB, 171 views)
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Old 14th November 2006, 12:02 PM   #27
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OTL output at 0.35W with 1Khz input signal, B+ with 1khzripple at 1V (this is normal for circlotron circuit, I was told)ˇAat 100Hz, there is 0.4V ripple (this is coming from the AC mains)
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Old 14th November 2006, 12:04 PM   #28
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When the amp is fully loaded, voltage on B+ is 147V, current 1.25A, 1Khz ripple at 7.5V, 100Hz ripple at 2V
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Old 14th November 2006, 12:09 PM   #29
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Now, we tested the OTL amp with SPS80HV for the B+ of putput tube. one module provide 170V and the other provide -170V

When no input to the OTL amp, B+ at172.5V with virtually ripple! Current = 0.35A
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Old 14th November 2006, 12:11 PM   #30
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OTL amp at 0.35W output, with 1Khz signal input. Measured at B+
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