6L6 bias?

[tubelovin]

How many ma on 6L6's in a 5E3 using the shunt method? Also what is the largest filter cap I can put in with a GZ34? The stock 16uf's don't seem to cut it.

Right now I've got 45ma on each with a 360ohm cathode resistor.

[Bruce / Mission Amps]

You are OK right now with the idle current.
I've used 50uF capacitance on GZ34s with no trouble.
I use a minumum of 20uF-22uF-450v/500v for the 6L6 5E3 amps for the firs two.
Actually, in the last 5E3 with 6L6s I made, I used three 22uF-450v caps and it worked fine.
It's more about what rectifier you have and if you use a 5Y3GT, don't go above 33uF, no matter what.
If you use a GZ34, you can use a 22uF to 47uF@450v/500v cap

[Amp Kat]

Bruce ,I'm assuming your talking about the little silver IC 22uf caps. I've been using them and have had no problems and the 47uf also with the GZ-34. Wouldn't it be safer to just read across the 360 ohm resistor and divide the voltage across it by the 360 ohms to get your current in ma's ? I've also seen motorboating with to low of capacitance with the GZ-34/AR5 but wasn't aware of the 33uf on the 5Y3 so thanks.

[tubelovin]

Thanks for the reply. I thought I was in safe range but it's good to know for sure. I've got a couple 40uf caps I'l try those.

What are those IC caps, are they those Illinois caps? Are they smaller compared to the sprague?

[Bruce / Mission Amps]

Yes reading across the cathode biasing resistor is fine as a pair of 6L6s at this voltage doesn't draw that much screen current to effect much.

I've been having terrific success with these 22uF@500v caps instead of the grossly overpriced Sprague ATOM caps.
That22uF@450v was a misstype by me... i actually was using the 22uF@500v caps.

The grey/silver IC caps are the only Ecaps in a power supply I ever had blow the end cap out of but I have had a fair number of the Sprague ATOMS be bad right out of the box.
Right now I am hearing through the grape vine that Sprague is trying very hard to eliminate the entire ATOM Ecap line and that's why the cost has doubled at wholesale in the last two years.

I, for one, will be dropping them from my kits pretty soon if the prices keep going up like this. Or at the very least I will sell the kits with a premium price adjustment for the Sprague ATOM caps.
IMHO and with respect to actual tone and the voltages in a tweed amp, I think the ATOMS are over priced, net driven nonesense anyhow and the German F&T or Gold Ruby caps are 100% as good or in some instances, even better.

Although I just bought the last of their 22uf@500v caps at Parts Express... they will be back in stock in late November...
http://www.partsexpress.com
Or, here at CE or AES:
http://www.tubesandmore.com/new/scri...m=C-ET22-500FT

Below is the Ruby Gold E cap... note that it also is rated at 105 degrees, not 85 like a Sprague ATOM.

[tubelovin]

I've used both the F&T and Ruby only once but have had great results.
I may stop buying those Spagues cause of the price. The others are far cheaper., and seem to be as good.

[Amp Kat]

Hey I have some of those Ruby 100uf @350 I bought by mistake but they are a solid looking cap and I may just switch to those. I also blew the end off of one of those silver salutes so I've been a little weary of them. Totally agree about the overhyped ATOM and their BS price which we talked about a few ago but hopefully these Ruby's will stay intact for awhile. Can't see why anyone would pay the extra for Atoms in your kits when these would be a sweet compromise to the problem but hey you know how this business is. Thanks again fellows

[Bruce / Mission Amps]

UH-OH!!!
New news from MOJO's website:

Sprague Atom important information:

Sprague Atoms have been considered by Sprague to be obsolete for more than the last 5 years. During this period they have continued to make them and we have all grown used to the idea that they would be
around forever. This complacency is now due for a rude awakening. Our regular schedule of 16uf/475v Atoms was just interrupted with notice that the price was going to increase to 20% more than what we sell them for at one piece. We have known that Sprague was not interested in continuing this line, but now it is apparent that prices will be raised until the production lines can be shut down. So what to do? Our solution currently is to work with the Tube Amp Dr on their successful capacitor line. As we run out of stock on each Atom type it will be replaced by the comparable TAD type. The physical size of the TADs will be smaller - and the price will be somewhat less
- but the operation will continue to be the same. If any of the values have shortcomings we will work with TAD to overcome them, but they have been very good about having the foresight to avoid possible issues with their products and the samples on the caps we have seem to be no exception. The 16uf/475v Atom as mentioned will be the first replacement and will be printed 16uf/450v. This designation is actually 450v nominal and can easily handle a 475v circuit. However subsequent runs will be made 475v nominal. There should never be an issue unless you have been
using Atoms in a circuit that achieves higher than 475v already.


http://www.mojomusicalsupply.com/cgi...q.html#sprague