Preamp Deal of the Century

The GZ34 and the Bendix 6106 are indirectly heated tubes, heater and cathode are parallel connected. Both tubes have the same base diagrams and both are bi-phase halve-wave rectifiers or full wave rectifiers.
"Slow start" means the warm-up "rise time" (time taken to change from 10% to 90%) of their output voltage when fully loaded, which reduces the inrush current of other electronic components.
I gathered this information from some books, I´m not a technician.
The question is, is it the same thing "indirectly heated" and "slow start", or in other words, all the indirectly heated tubes have slow start?.
When I asked Mick if I could use the U54, a tube with the same base diagram as GZ34 and that is also an indirectly heated rectifier, his answer was: NO!!! It is not slow start.
In some substitution book I found that the U54 can be used instead of GZ34...Could someone help and explain this technical issue?.
Slowhand here you have a very complete data for the Bendix 6106: http://www.mif.pg.gda.pl/homepages/frank/sheets/131/6/6106.pdf
(cut and paste in your browser).

Stiltskin, I am using the 1957 metal based Philips miniwatt in my Grange and it is absolutely spectacular. I replaced the 5881 regulators with a matched quad of 1952 Westinghouse 6F6GT. Hard to believe it could get any better.
Let us know what you think of the Philips GZ34.

Hi guys,

I was speaking with Mick about the new KT-88 based monoblock amps he is working on. He plans on offering a 50wpc version, a 100wpc version, and a intigrated amp version (sounds interesting). He thinks the price will be around $3000. That would be nice, but we will have to wait and see.

Mustang, I am also using the Phillips Miniwatt in my Cortese. It was a big improvement. I have had little success on the 5881's. I appreciate the tip on the 6F6GT's.

I just found out the Pat Malone (lugnut) died last week. I am very sorry to hear this, but I know he is in a much better place now. Pat taught me a lot about life and how precious it is. I will miss him very much.