Well here we go. I am in the process of wiring up my first DIY project, a complicated as hell (I used to use the word simple there) SET using EL34's. This may be really stupid and or annoying, but I am going to post a list of questions by number. That way if someone wants to comment on a particular question they can use the number. :D


1) How do I determine resistor wattage values? The schematic only gives a value for the cathode resistor on the EL 34's. (11watts)

2) Does it hurt anything to use larger watt ratings if your not using the rsistor as an overcurrent protection device as well?

3) Where can I buy an 11 watt 680 ohm resistor?

4) Is a 2 watt OK for the triode strap? It is 120 ohm.

5) Is it silly of me to buy way more resistors than needed so I can match them?

6) Would it be a good idea to add a bias pot, and if so how would I do this?

7) My opt's came with a brown and blue wire on the primary side and a green and black on the secondary. I have blue hooked to B+ and brown to the output tube. Green to spikker ground and black to spikker pos. Do the coils in the transformer care which end is which? I mean does the winder know + and - when he is done?

8) The only AC I have running up the chassis is the 6.3. It is tightly twisted, but are there other things to watch out for. It only gets near the input to hook to the 6SL7's.

9) Hey I think thats all for now! :banana:

I hate to ask such direct questions for fear of someone thinking I am being lazy. Trust me, I have researched (maybe to much to quick). I beleive I am at the point where I have to solder the stuff together and see it to get more understanding. I'm really looking for the whys and not just the whats. Heck this could be the ticket. Please reply if you can with answers, or add questions if you have some. My old man allways said "knowledge is power", and I think my battery is about dead on this one. Thanks, Jay :drool:

Well here we go. I am in the process of wiring up my first DIY project, a complicated as hell (I used to use the word simple there) SET using EL34's. This may be really stupid and or annoying, but I am going to post a list of questions by number. That way if someone wants to comment on a particular question they can use the number. :D


1) How do I determine resistor wattage values? The schematic only gives a value for the cathode resistor on the EL 34's. (11watts)

Power is i-squared-R, in amperes, and Ohms

2) Does it hurt anything to use larger watt ratings if your not using the rsistor as an overcurrent protection device as well?

Nope, size and expense may be of concern.

3) Where can I buy an 11 watt 680 ohm resistor?

You may want to be sure you need it.

4) Is a 2 watt OK for the triode strap? It is 120 ohm.

See how much current is flowing, and confirm a 2:1 safety factor.

5) Is it silly of me to buy way more resistors than needed so I can match them?

Not for PP, but for SE, the channel-channel match is going to be hard to find.

6) Would it be a good idea to add a bias pot, and if so how would I do this?

A bias pot is only going to be used for fixed bias, you'll need a negative supply to adjust with the bias pot first...:)

7) My opt's came with a brown and blue wire on the primary side and a green and black on the secondary. I have blue hooked to B+ and brown to the output tube. Green to spikker ground and black to spikker pos. Do the coils in the transformer care which end is which? I mean does the winder know + and - when he is done?

Only a little bit, the detail is a little bit complicated.

8) The only AC I have running up the chassis is the 6.3. It is tightly twisted, but are there other things to watch out for. It only gets near the input to hook to the 6SL7's.

9) Hey I think thats all for now! :banana:

:thmbsp:

I hate to ask such direct questions for fear of someone thinking I am being lazy. Trust me, I have researched (maybe to much to quick). I beleive I am at the point where I have to solder the stuff together and see it to get more understanding. I'm really looking for the whys and not just the whats. Heck this could be the ticket. Please reply if you can with answers, or add questions if you have some. My old man allways said "knowledge is power", and I think my battery is about dead on this one. Thanks, Jay :drool:

I put my responses inside your quoted post.
Douglas

Thanks Douglas, Trusty old ohms law. I will try and figure out exactley how much current will be present and do the math for the strapping and cathode resistors. If you don't mind I will post what I calculate to see if I do it correctly. The hard part for me will be determing how much current is present. Jay

Thanks Douglas, Trusty old ohms law. I will try and figure out exactley how much current will be present and do the math for the strapping and cathode resistors. If you don't mind I will post what I calculate to see if I do it correctly. The hard part for me will be determing how much current is present. Jay

Hey!!!,
I have strapped a few pentode finals as triodes, and measured voltage on the dropping R. All were safe with 1/2 watt resistors. I would suggest figuring out a maximum voltage across the R( based on its wattage rating ), and seeing if that looks reasonable to you for that app. The cathode R looks a lot simpler to me, and a bigger 'safety factor', that is to say a higher wattage R, might be a better idea.

cheers,
Douglas

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=017-680

Thanks for the link Paul. Very cool store with much shiny stuff. :yes: I added them to my favorites. Anyone familiar with the Kimber Caps (prop)? Looks like pretty good pricing for high end caps. :scratch2:

No, but I'm familiar with Mundorf M-caps. I find them smooth and detailed (if that makes sense :)) and they are also reasonably priced.

sorry for hijacking this thread even more, but has anyone tried Solen Fast Caps? tjey seem to be cheaper than auricaps etc. but are they significantly better than the regular boxy red-dipped mkp ones?

sorenj07, have you seen this page http://www.humblehomemadehifi.com/Cap.html ?