Sopht Amp resistors

[liddokun]

I've searched through the forums, and I'm still not really sure.  I'm planning on building a sopht 12v amp soon, and I'm doing it up point to point.  My question is, what kind of resistors should I use?  Is it fine to use the 1/4 watt resistors? Or should I up it to 1/2 watt or even 1 watt? I've never really worked with this stuff before, only stompboxes. I'm assuming since its 12vdc, the 1/4 watt resistors will be fine, but I want to be sure.  Also, the electrolytic capacitor, 16v cap will be fine as well right? Cause the circuits running on 12v anyways. Any help would be awesome.
Cheers

[soulsonic]

It depends on where in the circuit the resistor is!
1/4 Watt is probably fine for the majority of the circuit, but the cathode resistor for the output tube should probably be at least 1 watt.
You can use Ohms Law to calculate how much power each resistor will be dissipating, so that will be able to tell you for sure.

[liddokun]

will upping the wattage of the resistor for all of the resistors do any harm to the circuit? Is it like electrolytics where you have to have a minimum voltage, but its ok to go over?

[zyxwyvu]

will upping the wattage of the resistor for all of the resistors do any harm to the circuit? Is it like electrolytics where you have to have a minimum voltage, but its ok to go over?

Using a higher wattage than necessary won't cause any problems, besides possibly having trouble fitting the resistor in there.

[ambulancevoice]

id probably use some 1/2 w metal film resistors
there a bit higher wattage just in case, and the fact that there metal film will help lower noise a bit

It depends on where in the circuit the resistor is!
1/4 Watt is probably fine for the majority of the circuit, but the cathode resistor for the output tube should probably be at least 1 watt.
You can use Ohms Law to calculate how much power each resistor will be dissipating, so that will be able to tell you for sure.

i agree with this too

[liddokun]

Yes, I think I'll use 1/2 watt metal films, but I'm still a little concerned about the cathode thing mentioned above, so I'm going to do a little ohm's lawing just in case. 
Cheers

[petemoore]

Yes, I think I'll use 1/2 watt metal films, but I'm still a little concerned about the cathode thing mentioned above, so I'm going to do a little ohm's lawing just in case. 
  LArger R's take more heat/dissipate more heat.
  2 resistors dissipate more heat than one of course.
  Conditions which determine heat of R's is not consistant.
  Baked resistors aren't that bad for experimenting..you can easily put [very low tech..anything that smells hot, doesn't burn easily or much] heat sensors on them, but for 'use', [ie not babysitting] a bit of overkill is always nice.
  Caps...just don't exceed the rated voltage, and watch polarity.
  That barely skims surfaces, for more in depth..google 'capacitor' or 'capacitor rating', or 'resistor' etc. it's a real good idea to get some info about what is in your hand that you're about to hook up, before you hook it up, also look at the data sheets and ask questions.
  I'm not sure how 'they' rate resistors for current/voltage, I just use the easy way, if they'se gettin' super hot...1/2 the current per size or do something to increase heat dissipation, perhaps it's the 'smart amatuer' method, but it works heat problem?..put something bigger, or two of something bigger on there, the increased surface area will dissipate more heat.

[mydementia]

I put a build log together for the 12V 12u7/12k5 circuit from sopht.ca last year (http://www.freewebs.com/dbx-fx/sopht12k5v610.htm).
I used 1/4W resistors all over the circuit and followed my general 'rule of thumb' for capacitor sizing: always use caps rated at least 50% higher than the maximum voltage you expect to see.  I think I ended up with 25V electrolytic and the box caps are all 63V or 100V. 

On the Sopht amp line... I've been working with Gaussmarkov on a project for the 30V Sopht amp... we've got a verified PCB designed and I'm almost finished assembling the final prototype.  I'm also putting together instructions on bending up your own chassis and building a cabinet (why not make it complete, eh?).  I hope to get this out in August, so stay tuned...
Mike

[kurtlives]

If you have any resistors to drop down the voltage they will need to be more than 1/2W.

[liddokun]

I put a build log together for the 12V 12u7/12k5 circuit from sopht.ca last year (http://www.freewebs.com/dbx-fx/sopht12k5v610.htm).
I used 1/4W resistors all over the circuit and followed my general 'rule of thumb' for capacitor sizing: always use caps rated at least 50% higher than the maximum voltage you expect to see.  I think I ended up with 25V electrolytic and the box caps are all 63V or 100V. 

On the Sopht amp line... I've been working with Gaussmarkov on a project for the 30V Sopht amp... we've got a verified PCB designed and I'm almost finished assembling the final prototype.  I'm also putting together instructions on bending up your own chassis and building a cabinet (why not make it complete, eh?).  I hope to get this out in August, so stay tuned...
Mike

I'm well aware of your build log.  I've gone over it many times, and it helped me to decide to do this project.  I think I'm going to go with 1/2 watt metal film resistors in the end, because I'm doing point to point on turretboard anyways, so I'll have some space.  I'm also going to use either mallories or orange drops from smallbear, which one do you guys recommend? I doubt I'd be able to hear really any difference, and Steve sells em for basically the same price, but if you have any experience, which do you prefer more? The electrolytic I think I'll go with 25V radial.
Cheers