Weber WZ68 now NOT recommended on Weber website!

Good job Kentley!  I probably need some form of inrush current reduction with the straight diode replacement.  I will work on that.  The lights dim a little for a second when the delay relay kicks in - more than usual.

Skizo I wish the bucker idea with the main transformer was mine as that is a brilliant solution.   I got the notion from our forum member "peterh".   I'm sure a in/out switch would work on the bucker but would recommend only changing with power off and recheck bias afterward.
https://dynacotubeaudio.forumotion.com/t2403-howto-cut-5v-from-the-mains-line?highlight=line+voltage

Reading up on the rectifier options for the ST-120 build coming across this thread now and reading the current page for the ws1 rectifier on their site there is now an option for having a thermistor included in it for a few seconds warm up period - so would this ws1 with the thermistor require the delay board or not?

Roy D wrote:Reading up on the rectifier options for the ST-120 build coming across this thread now and reading the current page for the ws1 rectifier on their site there is now an option for having a thermistor included in it for a few seconds warm up period - so   would this ws1 with the thermistor require the delay board or   not?

IMHO, the delayed start-up board should be required on all VTA amps, regardless of rectifier style. It's the cheapest insurance money can buy. Also Roy's "yellow sheet" mod. From there your options are limitless.

I agree with deepee. The thermistor may provide a modicum of delay, but it may not provide enough (how many seconds in "a few"?).
The TDR allows you to choose any rectifier without concern. It's worth the piddling extra expense.
I've been running the naked Weber WS-1 for well over a year (with the TDR) and the real concern is, without sag resistors, your B+ may rise above the prescribed max. of 410 VDC. This will depend on your line AC. If that stays below 118, like mine (thank some god or other!) you should be fine.

hmm ok, I will put the TDR on the list.. thanks deepee, Kently!

so   my knowledge of circuits is not yet up to the point where when I look at the TDR board on the VTA site I can determine all the functions so
   would the TDR also eliminate 'filament flash' such as detailed in this circuit in the Carlsons Lab video?

*edit* re reading the tubes4hifi page on the TDR unit, I think the answer is   yes =}

Roy D wrote:
so   my knowledge of circuits is not yet up to the point where when I look at the TDR board on the VTA site I can determine all the functions so
   would the TDR also eliminate 'filament flash' such as detailed in this circuit in  the Carlsons Lab video?

*edit* re reading the tubes4hifi page on the TDR unit, I think the answer is   yes =}

Gaasp ..
This guy don't even know that telefunken tubes are not mullards, and that the
kind of "flash" discussed is limited to mullards ( phillips volvo etc)
BTW, the mullards don't exhibit broken filaments, thus this issue is a non-issue.

yay I like non issues ^^ But overal I gather this TDR does indeed slowly up the voltage on the heaters then enables the high voltage to come on which will indeed help the lifespan of the tube set which is a good thing. The only questionmark I had was the remark that the WS-1 has some construction differences which may result in 'not good things' when the main voltage rises too much..

Roy D wrote:yay    I like non issues ^^   But  overal I gather  this TDR does indeed slowly up the voltage on the heaters then enables the high voltage to come on which  will indeed help the lifespan of the tube set which is a good thing. The only questionmark I had was the remark that the WS-1 has some construction differences which may result in  'not good things' when the main voltage rises too much..

Roy, not sure about that with the TDR. I think the filaments light straightaway, burn for about 15 seconds, then the B+ comes on. Bob L,, Roy M., correct me if I'm wrong here. I'm not aware of an off-the-shelf device that defers filament lighting, although after watching your video it seems like a good idea.
Unlike light-bulbs, tube filaments are pretty tough so I don't believe much thought is put into their longevity.

The TDR delays the application of the High Voltage (B+) to the plates of the tubes. The voltage is applied instantly once the time limit has been met. It is used to allow the output tubes a chance to warm up prior to having high voltage applied to them. Another nice feature is a blip in AC power will cause the TDR to reset and delay the high voltage again so it helps with fast cycle issues.

nmchiefsfan wrote:The TDR delays the application of the High Voltage (B+) to the plates of the tubes. The voltage is applied instantly once the time limit has been met.  It is used to allow the output tubes a chance to warm up prior to having high voltage applied to them. Another nice feature is a blip in AC power will cause the TDR to reset and delay the high voltage again so it helps with fast cycle issues.  

Yes, I neglected to mention that. I prefer the protection of a manual-reset GFCI which shuts everything down at a power blip, and when the lights come back on you can then re-set it. Between the TDR and the manual re-set GFCI I've never lost a rectifier, cap or power tube, and power fluctuations are regrettably frequent during winters here.

Roy D wrote:Reading up on the rectifier options for the ST-120 build coming across this thread now and reading the current page for the ws1 rectifier on their site there is now an option for having a thermistor included in it for a few seconds warm up period - so   would this ws1 with the thermistor require the delay board or   not?

Point of order - wouldn't a WS1 with a thermistor be a WZ68? It's the thermistor in that what causes the meltdowns.

... which I might add was never a problem here ... then again, my custom chassi has a whole lot more air space for convection cooling so it won;t go nuclear ...

PS - I've got the manual reset GFCI adapter AND a GZ37 AND the "yellow sheet mod" AND a thermistor on the main AC line in ... do I still need a time delay board"  ;-}

sKiZo wrote:

Roy D wrote:Reading up on the rectifier options for the ST-120 build coming across this thread now and reading the current page for the ws1 rectifier on their site there is now an option for having a thermistor included in it for a few seconds warm up period - so   would this ws1 with the thermistor require the delay board or   not?

Point of order - wouldn't a WS1 with a thermistor be a WZ68? It's the thermistor in that what causes the meltdowns.

... which I might add was never a problem here ... then again, my custom chassi has a whole lot more air space for convection cooling so it won;t go nuclear ...

PS - I've got the manual reset GFCI adapter AND a GZ37 AND the "yellow sheet mod" AND a thermistor on the main AC line in ... do I still need a time delay board"  ;-}

Depends on your OCD levels. Me, I'd get one

I installed a TDR on my ST120. At the time I had a GZ34 rectifier in the amp. The rectifier arc'ed when the high voltage kicked in. I asked Roy about this and my recollection is that he suggested I shouldn't use a tube rectifier with the TDR. I then put my WZ68 back in the amp. The GZ34 got put in my Magnavox 9304 amp where it has been happy and works fine. Maybe Roy can refresh my memory.

I think in addition to the thermistor, a WZ68 has some big cement resistors for some voltage sag missing from the WS1.

I have been running the same WZ68 on one of my VTA 125s for over two years. I had to replace it in the other one but even that one lasted over a year.

Hmmmm.... This is going to look as if I am engaging in apostasy coming from me - but for those running their various amps without a cage, thereby exposing all to heat and voltage, it would seem that there is no particular reason to put anything on top of the rectifier, copper, solid, drilled or otherwise.

And, as there is at least some real-estate around the rectifier socket, building the components into a nice finned heat-sink seems to make sense. And with perhaps phenolic or silicon lagging, it could even be reasonably safe.

Thoughts?

http://kam-alu.com/pic/other/2013-10-22-19-32-017.jpg

I have drilled my WZ68 with three 1/4 inch holes on two opposite sides and a 1/4 inch hole on the top. I also have a 6 inch boxer fan that I use to help cool the power transformer. With both of these, I can easily touch the top of the WZ68 for a second or two with no discomfort. So, it seems to run at a nice, relatively cool temperature.

About a year after I got my amp my Sovtek rectifier I got with the amp died..I forgot if it red plated or just stopped working and as a solution to my situation it was recommend that I try a Weber WZ68...so I got two and popped one it that worked flawlessly for over a year. I did eventually put a Gold Lion rectifier in that works flawlessly but a while ago I was experimenting with a 6SN7 tube with an adapter in the center position on the board. As a precaution I put the original WZ68 in and so far the amp is still running flawlessly.

I'm thinking a possible reason for preferring the WS1, though Weber apparently doesn't say it, is that whereas a guitarist may favor a more "tubey" sound, a hi fi enthusiast may prefer a less colored sound.  Of course, the sag resistor is going to be a potential failure point.  The diodes, not so much, unless you exceed the PIV rating.  When I finish my M125's (hopefully soon) I intend to try the original GZ34 tube recifiers I bought with them, the WZ68 and the WS1.  I'll report back the results  

In addition to the elevated B+ voltage that will certainly be a factor with the WS1, one issue not mentioned here so far is transformer heating.  With 1 volt drop across the WS1, according to the spec, the peak charging current going into the filter caps is essentially limited only by the transformer windings.  For a given average current the duty cycle is going to be shorter, the peak current higher, charging the caps.  Since heat goes as I^2 R  that results in more heat in the transformer.  Has anyone observed excessive power transformer heating with the WS1?

Maybe the price increase discussed at the start of this thread was due to an increase in the price of copper.

I have my amps now for almost three years and I still have the same WZ68 in one of the amps. I have tried the GZ34 and the Mullard tube rectifier and always come back to the Weber WZ68.

I had two Weber’s go south over course of a couple years and at one point had a
Mouser cart with full compliment of upgrade diodes and resistors to rebuild them but never did it as seemed to be classic case of turd polishing a disposable part.  I think they are kinda sketchy inside, clever concept that suffers from corner cutting to hit a price point.  If they made a $50 version with an eye to heat transfer they might last a long time  

Got some NOS Millard’s a while ago and have never looked back.

Drill some ventilation holes.

eickmewg wrote:Drill some ventilation holes.

and play this to test it

Turn it up to 11 and that will do it.