Will the Paramount Soft Start retrofit eliminate the Ni cores magnetization?

xcortes · 3633

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Offline xcortes

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I remember in the past that this one of the advantages that a soft start would offer but have not read anything related since it's release.

Would be great if the answer is yes (my kits are still in the everyday slower Mexican mail system).

Xavier Cortes


Offline Paul Joppa

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No, it will not. The output transformer core is magnetized mostly by the current surge that charges the parafeed capacitor, which occurs before the power tube begins to conduct. The only solution is to short the output transformer primary winding with a relay, which opens up after everything is stabilized.

In the best of all worlds, I would add another PC board containing a regulated 6.3vDC supply for the driver heater, and three time delay relays to sequentially turn on the high voltage supply, then the soft start, and finally the output transformer. Among other problems, I have yet not found a place to put such a board without sticking out below the wood base or interfering with other components!

Paul Joppa


Offline xcortes

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Thanks Paul.

There had to be a downside for using Nickel transformers!

Xavier Cortes


Offline pro_crip

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I have to do some research on this as I bought the Magnequest iron upgrade with the Ni core. But to either calm my nerves or give me an excuse for another 5 mgs of valium, is Ni core magnetization a huge problem? I'm off to do some reading. Thanks for listening.


Rich

Richard J Feldman
Professional Gimp,connoisseur of Bourbon and Vinyl, metalhead

Crack, Extended FPIII, Eros, Paramount 300B's (in the midst of construction)

Tune down, smoke up


Offline xcortes

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Quote
is Ni core magnetization a huge problem?

I've heard of amps exploding because of it!

Seriously now, no big problem and it cures itself after about 30 mins of listening. It's very clear how the Ni amps sound much better at the second side of the first lp.

Xavier Cortes


Offline Paul Joppa

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We had a couple prototype ParaBees with delay boards in them. It was startling how quickly they come "up to speed" - it really clarified that the magnetizing effect was real. Incidentally, it's 30 minutes (more or less) of MUSIC to demagnetize the core; just turning it on and getting things warm is not enough.

I keep dreaming of making a pair of Signature Paramounts with all-film caps, sequenced relays, gain trim controls, DC driver heaters. But then reality hits - it wouldn't actually sound much better, it would just cost more.  :^)  Still, it would be fun!

Paul Joppa