18Watt.com

Is there anywhere that I can find a good list of components to have on hand? I've begun modding my JCA22H, but it would be cool to have plenty of parts on hand. Since I can't just drive down to the local Radio Shack anymore, it's not very convenient to order parts online, as I need them. Especially when they want to charge $8 to ship 2 or 3 50 cent parts.


Or, could anyone provide a decent list of components that are always useful to have? 

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ledvedder wrote: ↑

Mon 12/14/20 11:45 pm

Is there anywhere that I can find a good list of components to have on hand? I've begun modding my JCA22H, but it would be cool to have plenty of parts on hand. Since I can't just drive down to the local Radio Shack anymore, it's not very convenient to order parts online, as I need them. Especially when they want to charge $8 to ship 2 or 3 50 cent parts.


Or, could anyone provide a decent list of components that are always useful to have? 

I like CMF60 MF 1W 500V resistors. The values won't be exact for some, but they'll be close enough.
Resistance Ω:
200, 400, 680, 820, 1K, 1.2K, 1.5K, 2.2K, 2.7K, 5.6K, 8.2K, 10K, 15K, 22K, 27K, 33K, 47K, 56K, 68K, 82K, 100K, 120K, 220K, 330K, 470K, 680K, 1M, 1.5M, 2M, 2.2M is a good start.

For wirewound higher wattage resistors I use Dale, Ohmite, or Xicon:
3W Ω: 100, 1K, 1.5K, 2.2K, 3.3K, 4.7K, 8.2K
5W Ω: 150, 180, 200, 220, 470, 1K, 1.5K, 2.2K
10W Ω: 100, 150, 180, 200, 220

Capacitors:
Film:
pF: 200, 250, 500.
µF: .001, .0022, .0047, .01, .022, .047, .1, .68, 1, 2, 2.2, 3, 3.3
Electrolytic µF:
1, 10, 16, 22, 33, 47, 250, 1000, 2200.
Values don't need to be exact. 50 can replace 47, 20 can replace 22, etc...

Diodes: UF4007, 1N4744

Don't forget to stock up on your favorite switches, jacks, pilot lights, etc...

Those are all things I hang on to for 18 watt based circuits. You should review the schematic of what you're doing and see if anything is missing.

4-40 (or 4-48) machine screws, 3/8" & 1/2"
4-40 (or 4-48) nuts (plain, keps and nylock)
#4 washers (plain, splitlock, nordlock, internal tooth and external tooth)
...or M3 of all of the above if you prefer metric.
3/8", 1/2" and 5/8" grommets
octal to noval socket adapters

Don't forget:

G12M 55Hz
G12M 75Hz
G12H30W
Emi 1028k

I see the TMB Trem specs a 2M Audio pot for the speed control. Any idea where to find those?

EDIT: I was able to find a 2M Linear Alpha pot. No audio, however.

ViperDoc wrote: ↑

Wed 12/23/20 12:53 am

I see the TMB Trem specs a 2M Audio pot for the speed control. Any idea where to find those?

EDIT: I was able to find a 2M Linear Alpha pot. No audio, however.

I couldn't find any either. I used 1M, but the sweep could be better. I'm going to try a reversed audio .. they are more finetuning on the last quarter.

ViperDoc wrote: ↑

Wed 12/23/20 12:53 am

I see the TMB Trem specs a 2M Audio pot for the speed control. Any idea where to find those?

EDIT: I was able to find a 2M Linear Alpha pot. No audio, however.

2MA is left over from the original 18W schematic. I used a 2M Linear pot on my build. It's fine, I don't think it matters for speed control. Linear makes more sense to me anyway.

Any tips for making the tremolo oscillation speed *really* slow?

ViperDoc wrote: ↑

Wed 12/23/20 12:53 pm

Any tips for making the tremolo oscillation speed *really* slow?

The 3x .01uf caps... replace one with a .022uf for slower speed. On the tremolo TMB it's the 3 horizontal caps on the right side of the board, near the 1st preamp tube

I switched a red LED for the bypass resistor/capacitor on a Princeton Reverb build and that worked tremendously well. Not sure how to implement that in this circuit with the intensity control on the V1B cathode.

Just try the bigger cap. That's the way we all do this... it's really easy

Bieworm wrote: ↑

Wed 12/23/20 3:29 pm

Just try the bigger cap. That's the way we all do this... it's really easy

I did that as well, but the cathode LED swap made the biggest difference. I'd like to get the oscillation speed down to 1 Hz, and increasing the cathode resistor value according to Blencoe is the way to do that.

http://www.valvewizard.co.uk/trem1.html

Would the intensity part of the circuit function if it was separated from the cathode?

ViperDoc wrote: ↑

Wed 12/23/20 5:15 pm

Bieworm wrote: ↑

Wed 12/23/20 3:29 pm

Just try the bigger cap. That's the way we all do this... it's really easy

I did that as well, but the cathode LED swap made the biggest difference. I'd like to get the oscillation speed down to 1 Hz, and increasing the cathode resistor value according to Blencoe is the way to do that.

http://www.valvewizard.co.uk/trem1.html

Would the intensity part of the circuit function if it was separated from the cathode?

Only one way to find out
I wonder if anybody has performed a bias vary trem on the output tubes of an 18W
I have one on my imperial clone. No tube to oscillate, but an irf840 . Works really great and dead silent. No woof woof

ViperDoc wrote: ↑

Wed 12/23/20 5:15 pm

Bieworm wrote: ↑

Wed 12/23/20 3:29 pm

Just try the bigger cap. That's the way we all do this... it's really easy

I did that as well, but the cathode LED swap made the biggest difference. I'd like to get the oscillation speed down to 1 Hz, and increasing the cathode resistor value according to Blencoe is the way to do that.

http://www.valvewizard.co.uk/trem1.html

Would the intensity part of the circuit function if it was separated from the cathode?

Very interesting. I'd love to hear how your result sounds.

I don't know how the intensity pot would work not being connected to the cathode. Connected to the cathode, it looks like it's changing the bias of that triode, and bleeding some signal from the grid to ground. Without the bias change, it looks like it would be only a minor signal bleed to ground. It might have some affect, but I don't know that it would be that intense. You could try it as drawn, or you could instead use a larger value pot to get more range and see what happens.