Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Paramount => Topic started by: xcortes on February 24, 2011, 05:05:35 AM

Title: Will the Paramount Soft Start retrofit eliminate the Ni cores magnetization?
Post by: xcortes on February 24, 2011, 05:05:35 AM

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).

Title: Re: Will the Paramount Soft Start retrofit eliminate the Ni cores magnetization?
Post by: Paul Joppa on February 24, 2011, 07:41:21 AM

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!

Title: Re: Will the Paramount Soft Start retrofit eliminate the Ni cores magnetization?
Post by: xcortes on February 24, 2011, 07:43:42 AM

Thanks Paul.

There had to be a downside for using Nickel transformers!

Title: Re: Will the Paramount Soft Start retrofit eliminate the Ni cores magnetization?
Post by: pro_crip on February 24, 2011, 08:32:02 AM

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

Title: Re: Will the Paramount Soft Start retrofit eliminate the Ni cores magnetization?
Post by: xcortes on February 24, 2011, 08:34:26 AM

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.

Title: Re: Will the Paramount Soft Start retrofit eliminate the Ni cores magnetization?
Post by: Paul Joppa on February 24, 2011, 09:59:02 AM

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!