MF Resistor Question

[teleamp]

I have used some of the resistors from West Labs in a couple of builds with good results. My question is how do these compare to the Vishays? I am using Rikens on my TW build, but am considering going back to the red ones for future builds unless someone knows of a better MF.

Thanks
Mike

[Jim Donelson]

Well, there's nothing "wrong" with Vishay metal film resistors, except that the 1 watters from mouser are only rated to 250V. This mean the voltage drop across the resistor must be less that 250V.

The West ones are rated to 750V. Now, in most cases this is not a problem but in some cases it may be.

You should use the Vishay in "signal" circuits, and save the West ones for the plate resistor.

[Funkalicousgroove]

The West Plate Resistors aren't available in 150K, 120K, or 180K. The Dale RN65 Resistors are true Mil spec, which means that they're overrated: the published working voltage is 350, and they are called 1/2 watt-BUT in order to be true Mil spec they must qualify for the meets or exceeds act, and are actually good for at least a 50% increase in their rated values. These are what is in many real dumbles.

[Jim Donelson]

BTW Do NOT belive the audiophile CRAP about resisitors.

(or the tube amp guys crap either, but it tends to be less outragous and more honest)

Scientific tests have been done that prove the audiophiles are full of crap.
Listening tests are SO unreliable for some things.
For example, some percieve the noise of CC resistors as being "warmer" when if fact injecting white noise gave the same result.

I felll for it for a while, until I looked into it. It's easy to sucked in when so many testify, but the earth is not flat, even though at one time many belived it was.

MF are the best, just be sure the componet is properly rated and the correct value. The West ones are well rated and not too outragously priced.

[Funkalicousgroove]

Don't get me wrong, I use Dave West's Pots in my "Wrecks" with Fantastic Result, and I am all for his resistors as well, but he doesn't stock all the necessary values to use them for Plate Resistors in Dumble clones. you can rest assured the RN65's will hold up for a LONG time at twice their Voltage rating, that's what Mil spec is all about!!! here's a nice tip: All of the JAN/Phillips 5V4 tubes produced after (I believe) 1970 are actually re-labelled 5AR4/GZ34's so that they didn't have to re-design a military 5V4. That trend continues throughout most true Mil spec electronic products.

[Jim Donelson]

The West Plate Resistors aren't available in 150K, 120K, or 180K.

Good point.

The Dale RN65 Resistors are true Mil spec, which means that they're overrated: the published working voltage is 350, and they are called 1/2 watt-BUT in order to be true Mil spec they must qualify for the meets or exceeds act, and are actually good for at least a 50% increase in their rated values.

Can you get these other than surplus at a reasonable price?

These are what is in many real dumbles.

<b>So what</b> - well I guess since this is a Dumble forum, that has meaning. However, you can be sure Dumble used what was available and had the proper specs... Unlike Leo he was first and foremost an Engineer... NOT a Marketeer...

[Funkalicousgroove]

Can you get these other than surplus at a reasonable price?

Yeah, $.33 ea from Mouser.com

So what - well I guess since this is a Dumble forum, that has meaning. However, you can be sure Dumble used what was available and had the proper specs... Unlike Leo he was first and foremost an Engineer... NOT a Marketeer...

Well, we're all building Dumbles round here, so there is quite a bit of interest in what is in "Real" dumbles. I agree that he used what was available, but Big Metal film plate resistors seems to be a re-occuring theme. You can't argue that Plate resistors don't affect tone, and you certainly don't need any fancy gadgetry to prove that they do!

Oh, and before I forget, Welcome aboard Jim!! are you a cloner or just interested in Dumbles?

[Jim Donelson]

Thanks for the welcome.

I've built a few simple amps, and I'm considering a Dumble clone. Mainly because the guy was so interesting. Here's a guy who has the guitar amp world by the nuts - he could charge what ever - and what does he do ? Stop making 'em. Now that's cool. Of course, his circuits are interesting too.

It's also interesting that he so jealously gaurded his design - very unusual. But I'm begining to see that the circuit itself is not all there is to it. That the engineering is a big part of it, and the tweaking. He had an ear that could tell when all was right.

BTW - Your right about mouser, just read the specs carefully. I buy most of my parts there....

Thanks again...

[teleamp]

Thanks for all the information guys. I will give the Vishays a try. Got a few amps to build and then will be doing an overdrive reverb in the near future (bought iron to do a bassman, but can't resist that ODS type sound).

Thanks
Mike

[teleamp]

Here is a clip from a Bad Cat clone I built using almost all metal films from West Labs.

[teleamp]

Sorry, couldn,'t post mp3. Clips hosted at www.texastubeamps.com/Sounds.html


Mike

[dogears]

I believe the West resistors are made by PRP

CHeck this out. http://www.prpinc.com/pdf/GPSeries.pdf

Same red color, same size, same voltage rating.

I have a bunch. Somehow, I just prefer the RN65 by Dale.

Also, these PRP resistors go for about half of the West Labs price.

Here is Partsconnexion http://www.partsconnexion.com/catalog/resistors.html These are the 9372 series audiophool metal films.... Point is PRP is the maker of the West Labs resistors.

Click on PRP at the bottom.

[teleamp]

Thanks Scott, the prps were my first exposure to using metal films in my amp builds. I just got some Dale RN65s in from Mouser to try in a TW inspired build.

BTW, you got some chops dude.

Mike

[Funkalicousgroove]

FWIW, and just as another POV, Ken Fischer absoluteley HATES mf resistors, and says that he thinks they make guitar amps sound anemic! Just further evidence that beauty is in the ear of the beholder, and the proof is definitely in the puddin!

[glasman]

FWIW, and just as another POV, Ken Fischer absoluteley HATES mf resistors, and says that he thinks they make guitar amps sound anemic! Just further evidence that beauty is in the ear of the beholder, and the proof is definitely in the puddin!

Well I built a couple of d-clones a while back with 1W CF's in the plates and they sounded really good. So of course to make them better I replaced the CF's with XICON MF's.

Honestly they added such a edginess to the sound I had to pull them out and go back to the 1W CF's in those amps. I will be using the RN65's in all of my future amps. Enough input from trusted sources tell me this is the way to go.

IMHO you can hear the diffference in plate resistor types when you are pushing stages into overdrive. I have heard it on every d-type amp that I have built. YMMV.

Hey Funk, can you give me a call sometime at (800) 227-6462 ext 4483 in the Tempe office. I have a couple of offline questions for you.
Gary