RE: an additional case

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Posted by Ralph (M) on April 27, 2021 at 10:59:56

In Reply to: RE: Your magic wire sarcasm didn't elude me posted by awsjr on April 27, 2021 at 09:45:20:

The big weakness in the Dyna ST-70 is the rectifier not the power tubes. If the amp is run at high power on an on-going basis, the rectifier simply isn't rated to handle it.

If you replace the rectifier, the voltages aren't good- you really do need its voltage drop to be there.

They really should have used dual rectifiers but price and size were constraints. So you have the case where even the best rectifier you can find will be the first tube to fail in this circuit.

The rectifier diode setup is nice for that reason.

Alternatively Triode Electronics of Chicago makes a drop in replacement power transformer that allows for dual rectifiers. You have to find an alternative filter capacitor arrangement but these days that's not hard. So you can used the filter can location for the second rectifier in parallel with the first. In this case the rectifiers will hold up much better.

The funny thing about this to me is it would have been cheaper and as effective to make a drop in power transformer that simply was designed for solid state rectification and got you the right voltages when so used. But I think they may have been concerned about loosing the controlled warmup of the 5AR4.

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Follow Ups Full Thread

Topic - ss diode on gz34 - awsjr 03:32:44 04/27/21 (17)

RE: 1N4007's are going in..thanks for the help - awsjr 02:15:00 04/29/21 (0)

"preventive not an "enhancement" " - 1973shovel 06:59:57 04/27/21 (12)

Diode Tweak - Triode_Kingdom 13:31:02 04/27/21 (6)

RE: Diode Tweak - 1973shovel 06:18:27 04/28/21 (0)

RE: Diode Tweak - awsjr 03:35:51 04/28/21 (4)

RE: Diode Tweak - trobbins 16:21:36 04/28/21 (2)

RE: Diode Tweak - Eli Duttman 19:24:09 04/28/21 (1)

RE: Diode Tweak - trobbins 19:45:49 04/28/21 (0)

RE: Diode Tweak - Triode_Kingdom 05:46:18 04/28/21 (0)

RE: "preventive not an "enhancement" " - awsjr 08:20:39 04/27/21 (4)

Your magic wire sarcasm didn't elude me - 1973shovel 09:22:49 04/27/21 (3)

RE: Your magic wire sarcasm didn't elude me - awsjr 09:45:20 04/27/21 (2)

You're welcome - 1973shovel 05:02:13 04/28/21 (0)

RE: an additional case - Ralph 10:59:56 04/27/21 (0)

RE: ss diode on gz34 - trobbins 05:40:28 04/27/21 (2)

RE: ss diode on gz34 - awsjr 08:32:31 04/27/21 (1)

RE: ss diode on gz34 - trobbins 17:08:50 04/27/21 (0)

Follow Ups

RE: an additional case - Ralph 10:59:56 04/27/21 (0)

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