Resolved. Bung JJ out of the box    new pair of tubes and my oh my what an amp. Must remember to take the crap tube to my tube guy and get him to throw it in his tester and see what it turns out like.

Aye, im gonna pull the choke out and check both the resistances from the wires to choke frame and then get the old dremmel out and grind back some more of the powder coating on the chassis at the choke mountings. Have done a dark room test too to make sure there wasnt any visible arcing anywhere indicating a short of some sort, but that was clear. Thought it may have been a bad cap somewhere but none are giving the ol tell tale bulge, Its got to be the choke grounding fingers crossed cause in theory if the choke was ground i would be 12VDC all over the chassis not just on the choke frame.  oh the joys of trouble shooting

wondering if anyone has ever come across voltage on the choke frame/casing? Ive got this really weird issue, popping from speaker, and it changes tone. powered up a new hrm build a week or so ago, bulb limiter test was fine, tubes in voltages look ok, slightly hot but well within a 10% range. Continuity is good on all conections, ive been over this amp from both ends and all connections are spot on. Power tubes Biased up fine, PI trimmer bang on with V3A 6VDC higher than V3B. I pulled power tubes and popping stops, swaped them around and rebiased, this is where it got odd. This time i adjusted the bias with the tips of my fingers on the pot wedged between the choke and the power tubes trying very carefully not to get burnt from the heat coming off the 6L6s and touched the casing of the choke, well the popping stopped. Decided to get a reading off the choke casing to ground and the casing has just about 12VDC on it.  thats not normal is it? Could that be a grounding issue on the choke casing? Amp seems to play fine apart from the annoying pop. Any ideas? I dont want to just ground this thing if there is an underlying issue.

If your in any doubt regarding the shield between the OT and Pre amp tubes just put it in, its easy enough to do before you get to far through the wiring. I ran the DZ30 amp without it to start with then put it in later, I really didn't notice any difference in noise with it in or out, wonder if its more down to lead dress than anything, maybe just an anomaly, Pic attached where you can see it placed in the amp.

Just thought I should update this post, in case anyone else wanted to use this method of first time power up, since my build went off with out a hitch.  USE THE 60Watt Bulb!!!!  everything turned out fine, trust your multi-meter and if you have done the basic continuity checks and your voltages check out and are within expected ranges you should be good to go with installing your tubes and rechecking your next range of voltages.

Hoping someone can shed some light on something I'm seeing with a first time power up of a DC30 through a Light Bulb Limiter. Have been over the schematic / layout numerous times have done continuity checks all over the amp and all looks good. When using the limiter with a 25watt bulb, Limiter plugged into mains, Amp plugged into limiter, standby switch in  "Standby" and flip the power switch to the "On" position No tubes installed. The 25 watt bulb glows very faintly. repeated the process using a 40, 60, 75 & 100 watt bulb and none of them glowed at all, which is the result I was after. If the 25 watt bulb is passing the least amount of power to the amp is it this resistance that it is generating purely causing the bulb to glow?

from the above test, with the 60watt bulb in I am seeing the follow voltages, input 230v, seeing 225v at the IEC plug, mains fuse, on off switch as expected. PT secondaries are showing 275v at pins 5 & 7 of the rectifiers & 6.06v at the heaters (within expected values), so to me so far so good.

any ideas?

Thanks Charmcolors, did you put yours the full lenght of the preamp tubes or did you only make it slightly larger than the width of the OT, Like what Nik has done on the StrayCat model?

You could utilise Google Sketchup to whip up some conceptial design's for your cab, doesnt take much to figure out how to use it and there are plenty of tutorials available online if you get stuck. It's worked for me for both Head cabs and Speaker cabs and I have made up. saves you drawing something up.

Has anybody bothered to put the shield in between the OT and the Preamp tubes? Or is it quite enough with out it? wondering if any body had any pics of a build with the sheild installed. read somewhere that this could have benefits to reduce hum, and the kits look like they are now supplied with a piece of thin aluminimum for this purpose, well mine was anyway.