Three questions about 1Watt - 2Watts or 3Watt resistors?

[Homebelly]

I'm putting together a BOM for a JTM45 build.
I have a couple of schems and layouts to work from and i have come across a couple of irregularities.
So..

Question one;
On the main board there are two large resistors.
1 X 10K next to the 16uF cap in the middle of the board.
1 X 8.2K up near the 10uF caps.

On the schem i have from the metro instructions it shows these to be 1 Watt.
But i also have another schem and a couple of layouts, including the one from ceriatone, that show these to be 2 watt for the one closest to the 10uF can's, and 3 watt for the one next to the 16uF can.
I have another layout that shows both as 3 watt.

So, whats the deal here?

I'm planning on using valve storm to get most of my parts and they have both of these resistors down as 1 watt, and Georges picture of his GPM45 seems to show this also, so if its all good with George.. its all good with me. I'm just curious why there might be a difference. What would be the reasoning behind this choice?

Question 2
I have seen some gut shots of JTM45's that seem to have a 1K resistor running from the 8.2K resistor and choke on the board to pin 6 of V4, the first KT66 after the 12AX7's.
This is in the schem, but not on Georges GPM45.
What is this doing?

Question 3
On the ceriatone layout, as with most of the layouts that Nik produces, there are 1R 1Watt resistors tying pins 1 and 8 on the KT66's together and then going to ground. There are also two 5k6 1Watt's running from pins 5 on the KT66's to the two 220K bias resistors on the board between the two 0.1uF caps..( at least, i think these are the bias resistors,,i'm still learning this stuff..).
What are these there for?

Cheers for any help in this regard.
Its all about learning my way through this.

OH!.. and happy New Year!!

[toner]

I can partially answer your questions but someone like neikeel will likely fill in the gaps.

Question 1: I'm not sure which wattage is historically correct but I think they should be 2 watts. 3 watts is definitely overkill for those.

Question 2: The extra 1k resistor lowers voltage and current to the power tube screens. I don't know how this affects tone, etc. however.

Question 3: The 1 ohms are for biasing. The 5k6 are "grid stoppers", which form a low-pass filter with the tube's input capacitance. They're mainly used to suppress possible high frequency oscillation.

More info:
http://www.freewebs.com/valvewizard/gridstopper.html" onclick="window.open(this.href);return false;
http://www.aikenamps.com/InputRes.htm" onclick="window.open(this.href);return false;

[Homebelly]

I can partially answer your questions but someone like neikeel will likely fill in the gaps.

Question 1: I'm not sure which wattage is historically correct but I think they should be 2 watts. 3 watts is definitely overkill for those.

Question 2: The extra 1k resistor lowers voltage and current to the power tube screens. I don't know how this affects tone, etc. however.

Question 3: The 1 ohms are for biasing. The 5k6 are "grid stoppers", which form a low-pass filter with the tube's input capacitance. They're mainly used to suppress possible high frequency oscillation.

More info:
http://www.freewebs.com/valvewizard/gridstopper.html" onclick="window.open(this.href);return false;
http://www.aikenamps.com/InputRes.htm" onclick="window.open(this.href);return false;

Are..
Very cool..
The information about the grid stoppers is very cool.
Are you able to tell me if there is a way to tell how many watts a resistor is by looking at it?
Its my understanding that the coloured bands indicate resistance and the gold or silver band indicates tolerance as a %, gold being 5% for example..

[neikeel]

Toner has pretty much said it all.

The first amps had those droppers as 1watt carbon comps, then the Pihers and then Iskras, all 1 watt rating. Some mid 70s amps seem to have used 2w metal oxides but only sporadically.
For a good clone 2w metal oxide (ie flame proof) are best used for these. They also span the full width of the board easily, have no effect on tone.
The flying resistor from turret to first screen will lower the screen voltages a little, if you use them they can add a little compression to the tone but are not vital, the Metro amps do not use them as George preferred the more open dynamic sound without it - but you can try with and without, I think you will find the difference quite subtle. Make sure you use the other screen resistors on the valve base (1k for EL34s, 470R or 1k for KT66).

I would fit the 1ohm bias resistors and the 5k6 swamps as well.
Silver = 10% tolerance
Gold = 5%
Red = 2%
No you cannot tell purely by looking at the size Valve storm have the correct sort - pretty much one stop shopping there for most of the goodies you need.

n.b. The bias resistor should be 1%.

http://www.elexp.com/t_resist.htm

[Homebelly]

Cheers..

Valve storm is fast becoming my one stop shop.
Very cool site.

Cheers for your help.