If anyone is still looking for a SLP-98

@billpete , please rest assured that you did not take over the thread, and even if you had, it wouldn't have been a problem as it was kind of an open ended thread (open to anyone who was looking for a SLP-98).  Anyway, on A'gon threads often evolve into threads within threads and can be quite helpful and informative in that manner, and that is one of the tings I like about A'gon threads.  Anyway, I didn't intend to insult you or anyone else, so if it's all good, I'm happy.

@immatthewj 

It has been very informative. I'm happy too. 

Greetings immatthewj.  If you’re only seeing one diode rectifier, it’s probably the negative bias supply rectifier.  I do put HexFreds in the bias supplies of my personal amplifiers.  Had a hard time telling if it really helped there though, but figured it couldn’t hurt.  Because like the old saying goes, everything matters.  I do know adding more filtering to the bias supply definitely makes a cleaner sound quality.

The V12 amps should have four strings of three diodes totaling 12 diodes for the high voltage supply.  There is such a high current draw (large caps) that there are three in series for what should be one diode in order to keep them from blowing out from the turn on surge.  I remember doing a few amplifiers (not just V12’s) with HexFred’s, but that gets very expensive as you’re installing 12 so most people didn’t want to do it. In fact, I think on a pair of CAD-805 amps we installed 16, four sets of 4 just to make sure the amp never came back with an issue.  Now days, there are higher current HexFred’s available that can be used but you still want a couple in series.  I’ve had to buy some of these because I use so many large value capacitors in my mono-block PS’s.  My amps have two amp chassis’s and two power supply chassis’s. 
It’s not that you’re drawing a lot of current tube wise. It’s the turn-on surge to charge the capacitors.  The more capacitors, the bigger, the surge, and the more the rectifiers see a short initially at turn on.  

It’s not that you’re drawing a lot of current tube wise. It’s the turn-on surge to charge the capacitors.  The more capacitors, the bigger, the surge, and the more the rectifiers see a short initially at turn on.  

Thanks, @harpo75 , and that would explain why that when I had a Cary DIY  external power bank (four more large caps) hooked up I was frequently blowing fuses on start up.

The V12 amps should have four strings of three diodes totaling 12 diodes for the high voltage supply.

And thanks for that; now I will know what to look for.  If I can find the part in question, I can usually change it.

There may have been some V12’s with only four diodes.  Two strings of two in series but mostly it should be the later that I explained.  
My dual-mono amps I built have essentially the V12 input circuit but using a 6SN7 instead of the 6922 and are fully balanced.  The output is essentially the SLAM-100 but with everything taken to the maximum.  I have large cap banks and 10Hy chokes on the B+ and running 550VDC to four KT-150 tubes.  Then another  20Hy choke before the regulator circuit for the input tubes. Lots of Polypropylene al through the PS. I get a very nice 124 watts per channel output.  These drive my Eminent Technology LFT-8b speakers that I’ve completely rebuilt the crossovers.  I use a couple Rythmik F12 subs for the low end driven by the preamp with balanced cabling.  Going fully balanced made a big improvement in imaging for me.