Resistors

[NYListens]

I am in the middle of a 500-S restoration and need to replace a few resistors. I am would like some opinions on resistors. I ran to my radio shack and purchased some of their resistors and wasn't sure if it made any difference in the sonic quality of an amp or receiver, as capacitors can. I know there are a few types of resistors out there, but don't know a thing about their differences. Is it ok to use rat shack resistors???

 

[Steve O]

You don't have to ask permission to use RS resistors or any other appropriate component for that matter. If the RS resistors are the correct values and ratings AND you don't find anything wrong with the sound, don't worry about it.

I'm not familiar with the guts of the 500B (500S???) but I am with a lot of other Fisher units of the era. A large majority of them used really decent Beyschlag (sp?) carbon film resistors (deep maroon bodies). These things were and are stable and good sounding and rarely require replacement.

Last I looked, RS was stocking what looked to my eye to be Yageo brand CF resistors from Taiwan...reasonably decent in their own right. A few years ago there was general forum buzz about what great sounding resistors they were esp. considering the general availability although they're not cheap in the RS format. I suspect they've fallen out of favor by now considering the mercurial tastes of the opinion making true-believers. No matter if all you have to satisfy is yourself.

Bottom line from my POV is use RS resistors and enjoy unless the restoration is for someone else who has definite ideas as to replacement parts.

 

[NYListens]

You don't have to ask permission to use RS resistors or any other appropriate component for that matter. If the RS resistors are the correct values and ratings AND you don't find anything wrong with the sound, don't worry about it.

I'm not familiar with the guts of the 500B (500S???) but I am with a lot of other Fisher units of the era. A large majority of them used really decent Beyschlag (sp?) carbon film resistors (deep maroon bodies). These things were and are stable and good sounding and rarely require replacement.

Last I looked, RS was stocking what looked to my eye to be Yageo brand CF resistors from Taiwan...reasonably decent in their own right. A few years ago there was general forum buzz about what great sounding resistors they were esp. considering the general availability although they're not cheap in the RS format. I suspect they've fallen out of favor by now considering the mercurial tastes of the opinion making true-believers. No matter if all you have to satisfy is yourself.

Bottom line from my POV is use RS resistors and enjoy unless the restoration is for someone else who has definite ideas as to replacement parts.

I suppose it sounded as if I was asking permission, I was really more soliciting opinion. Thanks for yours. The 500-S is more rare than most of the other Fishers. It has a gold faceplate and requires an external MPX decoder to play FM stereo, otherwise it is all hi-fi Stereo as is. It was an earlier model than the 500-B, 400, 500-C, etc. and it has 7189 output tubes and not 7591s.

 

[asoundhound]

keep tolerance ratings in mind. two resistors with the same ohm rating are not necessarily equal!

say replace two resistors, one for left, one for right. let's use 100 ohms as an arbitrary rating. using 10% tolerance resistors, one could actually be 90 ohms and the other 110 ohms. this could affect the sonics!

Radidio Shack resistors, i believe, are 10% tolerance. they will work fine for most applications.

if having the very best is important to you, you may want to consider using resistors with tighter tolerances, even though they are a little more expensive and harder to acquire.

DISCLAIMER: i am not an electronics expert by any stretch of the imagination!

 

[brad347]

keep tolerance ratings in mind. two resistors with the same ohm rating are not necessarily equal!

say replace two resistors, one for left, one for right. let's use 100 ohms as an arbitrary rating. using 10% tolerance resistors, one could actually be 90 ohms and the other 110 ohms. this could affect the sonics!

Radidio Shack resistors, i believe, are 10% tolerance. they will work fine for most applications.

if having the very best is important to you, you may want to consider using resistors with tighter tolerances, even though they are a little more expensive and harder to acquire.

DISCLAIMER: i am not an electronics expert by any stretch of the imagination!

...or you could just use this handy gadget called a multimeter and measure them, when matching is critical.

 

[asoundhound]

...or you could just use this handy gadget called a multimeter and measure them, when matching is critical.

oh, sure, if you want to do things the EASY way...

 

[Redboy]

I think most of the RS resistors are better tolerance than 10% now, but either way brad's right - your multimeter can tell you.

If you want to foray into the world of "high end" resistors, check out the selection of stuff at partsconneXion (look for a banner link at the bottom of this page, they're an AK sponsor). They have offerings from $0.20 to $20.00 per piece. I've personally used the PRP, Kiwame, and Riken lines in different builds. I'm not sure I can hear a difference, but I haven't heard my amps with the RS resistors in them, either. Of the three I mentioned, I really like working with Kiwames. They have 1% tolerance, fairly sturdy leads, and the values are printed right on them, so you don't have to decipher color band codes on the fly. They run $0.99 apiece for the 2W versions.

If you do buy something from partsconnexion, be sure to pick up some of their teflon spaghetti tubing for lead insulation, too. That stuff is kind of hard to find elsewhere!

 

[Oerets]

NYListens,
It more then likely really doesn't matter as long as the wattage is the same or higher what type you use to replace a carbon resistor with . I try to use Metel Oxide Flameproof as much as I can , but a common carbon goes in if that's all that available .
Now the Wire and ceramic ones should only be replaced with the same type ..




Barney

 

[NYListens]

NYListens,
It more then likely really doesn't matter as long as the wattage is the same or higher what type you use to replace a carbon resistor with . I try to use Metel Oxide Flameproof as much as I can , but a common carbon goes in if that's all that available .
Now the Wire and ceramic ones should only be replaced with the same type ..




Barney

Thanks. By the way, what are the wire and ceramic ones used for? What is different about their perfomance?

 

[GordonW]

IMHO, carbon-film resistors are a good "compromise" for vintage units.

There is some evidence, that metal-film resistors can upset the tonal balance in some vintage audio units (making them "bright" or "hard" sounding), while original-style carbon-composition resistors are SO variable and unpredictable in performance (they drift badly, in some cases)... that leaves carbon film as a reasonably stable, reasonably "normal-sounding" resistor for these units.

I've tended to use these carbon-film resistor whenever possible... fortunately, they're relatively easy to get (Mouser, DigiKey, Radio Shack, etc, etc, etc...). As mentioned above, it's good to get MORE quantity than you need, for two reasons: 1) it's easy to accidentally break off a lead, and it will happen at the time where NOBODY is open to get a replacement (ie, like Sunday night), and 2) it makes resistor-matching possible. Getting the tolerances close can and will usually make for better soundstaging/imaging (better control of gain, so both channels behave the same as far as level, feedback, and such, are concerned)... both channels will wind up at closer to the exact same volume level at the same volume control setting, that way...

Regards,
Gordon.

 

[merrylander]

Wire wound and ceramic (also called 'sand' ) resistors are generally in higher wattage ratings than carbon film. The wire wound also come in lower wattage ratings in the 1% category.

Few vendors used better than 10% and in cheap table radios you were lucky to see anything better than 20%.

 

[Old1625]

I've been using "flameproof" resistors of a number of brands for many years, with no complaints.

As far as tolerance is concerned the best method is to check each resistor on the ohmmeter, as previously mentioned.

You can use a carbon composition resistor in plate load service and have it be noise-free--if you are the lucky type. I've seldom been, and have little use for that kind of resistor at this point.