Variac differences and use

A unit like this(10A) would suit your purpose nicely: (http://cgi.ebay.com/PowerStat-3PN116B-Variac-Variable-Transformer_W0QQitemZ220451775080QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3353f32268&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1205%7C293%3A1%7C294%3A50) I've always powered equipment up, and monitored power supply voltages without the tubes in the circuits(whether new construction or old gear), to be certain everything was working as intended. If a cap is ready to blow at operational voltage; it will(whether you take three days to bring it up, or three minutes).

I guess I've been extremely lucky all these years. The First Tube amp I built was a Dynakit ST-70. Their instructions(upon assembly completion)were to first test the voltages out of the power transformer, then insert the rectifier and test the voltages at the multi-section cap. Insert the tubes, connect input and output and play the sucker. I've followed those directions ever since(with variations according to circuit design), when assembling amps or upgrading their power supplies(quite a number). The most recent being the addition of 4 strings of IXYS FREDs in my Cary monoblocks, a few months back. Never have had a voltage issue of any kind. Maybe I AM living right after all?(NAH- That CAN'T be it) =8^)

You're right, and I've always considered the caps that were manufactured long enough ago to present a problem, inferior to current ones(whatever the year I was working on unit). I always replaced/upgraded the capacitance when doing a PS, or recommended doing so(if an older unit was opened for any reason). It was nice when the large Rubycon Black Gate electrolytics were readily available, and at reasonable prices(fond memories). I wish Sanyo would offer their OS-CONs in higher voltages and capacitances.