Is this safe? Using different type resistor

[glynnw]

Tonight, after reading the info below on changing tube sockets, I decided to tighten the loose contacts on my stock Paramount sockets.  In so doing, I absolutely destroyed the 220 Ohm 1/4 watt carbon composition resistor between teminal A3 and 7L on one of the amps.  Against all odds, I had a new pack of 220 Ohm 1/2 watt ceramic resistors (why or when I bought these is anyone's guess - the very fact of having them means I really need to buy some lottery tickets tomorrow.)  So the amp is again working.  Do I need to get a 1/4 watt carbon composition resistor for this position, or am I OK with the 1/2 watt ceramic?

Also, will changing these sockets out for the more expensive ones mentioned in the below post eliminate their getting loose, or do all types eventually get loose?

I really have to stress that my having these resistors on hand confounds me - my normal approach to repair is to send it off  to Chez Bottlehead.

[Paul Birkeland]

Excellent work on the replacement, the 220 ohm ceramic resistor will work, but I'd go for a carbon film, metal film, tantalum, or carbon composition resistor in that position.

In my experience, all types of sockets can get loose with a lot of tube rolling, but replacing a 4 pin socket isn't much of a chore.

-PB

[glynnw]

Thanks Paul - Upon further study the resistor I used is probably not properly classified as ceramic, but is some sort of film.  It is a small Radio Shack made in China  - 6 resistors in a pack with no markings as to composition.  Since my amp is still playing several hours later, I will just leave it until (if) I decide to replace the sockets.  Let me ask this.  If I am going to spend the bucks for nice sockets, I might as well get 2 quality resistors for this position.  Any recommendations on what I should use from the millions available?  I ask this because I sometimes see PJ explaining that a certain type of item was used because it was the best "in that particular case" even though that type of part was generally not considered the highest quality available.

Thanks again.

[Paul Birkeland]

Oh, you might be able to make a very educated guess just based on the color of the resistor body.

If it is kind of an almond color, it's mostly likely a carbon film resistor, which is a good choice for this position.

If it's a pale, shiny blue color, then it's most likely a metal film resistor, which is also a good choice here.

If the body is not shiny and is rough to the touch, then you might have a metal oxide resistor, which isn't thought to be so great for that position.

If the resistor is a carbon film or metal film, I wouldn't worry too much about buying a botique resistor for that position. 

-PB

[glynnw]

Almond it is (but surely there is some uber expensive replacment that will make me sleep better - made of wine soaked wasp wax or some such and only available from  one vendor in an ex-communist country)

Just to keep things consistent, I will replace the other one to match this when I next venture under the hood.

Thanks for the help - last night I was dreading not having my stereo for a few weeks - now it is back to the music.

[earwaxxer]

I replaced all of my resistors with Tantalum's - I sleep pretty well with that!

[Paul Birkeland]

Wow, I'm impressed that you could find all the values!

[Paul Joppa]

I often wonder, what exactly IS a tantalum resistor?  :^)

There are many "authoritative" answers on the web, not all the same. Qvortrup says the original AN tants were tantalum oxide. "Metal oxide" is usually a dirty word in audio circles, but I've not found any other reference to tantalum oxide. Wikipedia lists cermet (conductive metal ceramics) as including "tantalum nitride (TaN), ruthenium oxide (RuO2), lead oxide (PbO), bismuth ruthenate (Bi2Ru2O7), nickel chromium (NiCr), or bismuth iridate (Bi2Ir2O7)". Tantalum nitride is highly resistant to corrosion in a moist environment - the normal non-audio reason to use it.

All these materials are used in metal film resistors (most often NiCr, applied with several techniques on cylindrical insulators and laser-cut in a spiral pattern), thin-film (sputtered onto a flat surface and etched to trim), and thick-film (mixed with powdered glass and glue and screened onto a surface). These types can range from excellent to total crap for audio purposes; a tantalum oxide bulk-film resistor would be a poor choice!

Bulk foil is usually given first place; there are 3 or 4 alloys used but I've never seen anything about their composition or whether they use any tantalum at all.

Choice of material often depends on the desired resistance, so you may find some resistors that are TaN in a certain value range but other materials in other resistance ranges. All I ever see from suppliers is "these are Magic Tants - give me your money!" so I'm never sure what they actually are.

[earwaxxer]

Yep - I did do a bit of reading on the 'tants', and the formulas can vary. From the DIY forums that I read, the Japanese and Audio Note tants are the ones to get. The only site I found them for reasonable sums was the DIY HiFi Supply. They do ship from China, and it was amazing how quick they 'shipped'. I think I remember getting them in less than a week! 

I mean, I dont know how much of a difference resistors really make. Certainly large values would be the place to start. Since I replaced them all of them at one time I dont know what values and positions would make the most difference.

Here is the site:
http://www.diyhifisupply.com/node/152