Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dujuarez on November 07, 2016, 01:51:26 pm

Title: Question about Resistors
Post by: dujuarez on November 07, 2016, 01:51:26 pm
I have question relating to resistors. If the schematic calls out for a 470 Ohm resistor, can I use a 3 Watt 470 Ohm? I am assuming that I couldn't go the other way due to the voltage going across the resistor. If schematic called for 3 watt resistor I wouldn't be able to lower the wattage. But would there be any difference if I raise the the wattage of the resistor?




Thank you. 
Title: Re: Question about Resistors
Post by: jjasilli on November 07, 2016, 02:04:28 pm
It will be safe to use a resistor with a higher wattage rating.  Tone is an open issue -- there seems to be no agreement if different types of resistors sound different.  The dispute is worse in the hi-fi world.
Title: Re: Question about Resistors
Post by: sluckey on November 07, 2016, 02:05:24 pm
You can use a higher wattage resistor.
Title: Re: Question about Resistors
Post by: PRR on November 07, 2016, 02:32:58 pm
From yesterday's post on another forum:

> I couldn't get ...1/4w resistor so the guy said use a 1/2w as it had the same size legs

Might as well say it has the same number of legs.

ALL modern resistors have way-skinny legs, and are pretty sure to fit your holes.

If not, time to learn how to drill.

I'm having a party. I need to fetch 200 kG of beer. That's almost 1/4 ton. I go out in my driveway-- no 1/4 ton truck!! What to do?

Can I use the 1/2 ton truck?

Yes, of course, almost certainly. A 1/2 ton truck will carry a 1/4 ton load no sweat.

At least 99% of the time. Actually 1/4 ton trucks are rare in the US, but common in Japan. There, they are built less than 5 foot wide, to fit narrow alleys. My 1/2 ton truck is over 6 feet wide. If I have to get through a 5 foot gate at the beer store, I'm in trouble with the 1/2 ton, in-like-Flynn if I had a 1/4 ton.

That's the only "problem" with a 1/2W resistor where a 1/4W would be OK. If the layout is very tight, a 1/2W may not fit the available space. Most layouts are not so tight that you can't get it in there. Maybe crooked, but connected.

And price. When I was young, 1/2W was most common and thus the cheapest type. 1/4W and 1/8W parts were for hearing-aids and space-rockets and cost much more. Since then everything has got smaller. 1/4W is now the most popular and cheaper than 1/2W. The difference is never enough to bother a DIY budget.
Title: Re: Question about Resistors
Post by: dujuarez on November 07, 2016, 04:03:15 pm
Thanks everyone for answering so quickly. I sort of figured along those lines. But when your new you sometimes doubt yourself and need help from experts.




Again, Thank you.
Title: Re: Question about Resistors
Post by: uki on November 07, 2016, 04:21:25 pm
This is very good info about resistor, check it out: http://www.aikenamps.com/index.php/resistor-types-does-it-matter (http://www.aikenamps.com/index.php/resistor-types-does-it-matter)

See also: http://www.aikenamps.com/index.php/white-papers (http://www.aikenamps.com/index.php/white-papers)
Title: Re: Question about Resistors
Post by: tubeswell on November 07, 2016, 05:11:52 pm
Also, higher power handling = less hiss/noise floor overall
Title: Re: Question about Resistors
Post by: drgonzonm on November 09, 2016, 06:55:00 pm
ssh...   don't tell prr, but 1/4 ton trucks are relatively common on the US highways.  The secret is that they are not sold as 1/4 ton trucks, but SUVs.  my RAV4 has an 800 lb load limit, and is registered as a truck.   :icon_biggrin:   Another common source of 1/4 ton trucks are Jeeps, the old cj3s cj5s and cj7s were 1/4 ton trucks.  But let's keep it quiet, we don't want PRR made at us.  ( :dontknow: