Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

Return to Tube DIY Asylum

Message Sort: Post Order or Asylum Reverse Threaded

Resistors - noise

81.237.196.31
Posted on November 16, 2014 at 07:50:14
Stewen
Audiophile

Posts: 414
Location: Sweden
Joined: December 25, 2003
 Hallo ! Have a lot of different resistors , both new and old , carbon comp., carbon film , metaloxide and metalfilm . I would likt to have a possibility to measure how much noise they are generating , or letīs say
a chance to pick out low-noise resistors . For example : from a lot of 10
different 100K resistors choose the one with the lowest noise ( then use it as an aanoderesistor for a 12AX7 stage ). I plan to try to put 200 VDC over the tested resistor and then try to use a Darlington set up to amplify
the noise and then connect my oscilloscope to see what Iīve got .... Do You
think this would work ? Or are there better ways to sort out resistors
for the purpose I mentioned ? Thanks for some reply here .
Regards Stewen
PS. In one of his books , Gerald Weber says: " buy Allen Bradley carbon
comp. resistors when repairing an old amp, donīt use those cheap carbon film resistors You can buy from Hong Kong " . ( this he claims even if carbon film generally should give lower noise )

 

Hide full thread outline!
    ...
RE: Resistors - noise, posted on November 16, 2014 at 08:26:02
FenderLover
 Hi there Stewen! That article by Weber must be a bit old. Hard to find a range of NOS A-B cc resistors these days. Expensive, too. I have a stockpile that I use in signal path and other positions that may make a difference, tone-wise. Good metal-oxide work just as well elsewhere. IMHO, of course.

I've been using wire-wound in the PSU and cathode-to-ground (cathode biased) output stages. Seem to work fine. And low-noise, too.

-----

photo PSUafter_zps8789ef43.jpg


photo reverbtank_newdiodes.jpg

 

RE: Resistors - noise, posted on November 16, 2014 at 08:33:06
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 Conceptually, your idea is great. In practice, it becomes pretty difficult to look at resistor noise on something like a metal film resistor. You may need to construct a shielded area for your darlington amp, and you'll have to repeat your measurements several times to ensure that you aren't measuring the noise from your cell phone or wifi router.

 

The noise is random.........., posted on November 16, 2014 at 10:38:07
Alpha Al
Industry Professional

Posts: 2958
Location: N. Carolina
Joined: February 16, 2004
Contributor
  Since: December 3, 2015
 and also temperature dependant. If you can come up with a way to average your results over a period of time, what you are proposing might work.

 

RE: Resistors - noise, posted on November 16, 2014 at 10:46:58
Stewen
Audiophile

Posts: 414
Location: Sweden
Joined: December 25, 2003
 Thanks Guys ! I have bought about 3000 quite large , some 30x6 mm , 10 ohm
to 10 Meg. carbon comp. from our Radio Museum here in Gothenburg . Nobody
wanted them.... Guess they are 1 W or so . Also from ebay , Hong Kong ,
1W and 2W carbon film and metalfilm , in kits , 10 pieces each value .
Canīt find any disadvantedges with them except that the connections are a
bit thin ..... and perhaps of iron ... they stick to a magnet !
Another question : theres a company , TAYDA ELECTRONICS , HK , that I buy from , specially small electrolythic caps ( 22uF/50V for cathodes , 100uF/
100V for biascircuits and many more values . These caps work fine .....
whatīs your opinion ? It looks to me that this type of massproduced small caps are everywhere also in more expensive home-equipment . ( In tubeamp-powersections I use F&T from Germany ). Steven

 

RE: Resistors - noise, posted on November 16, 2014 at 12:51:42
tubular.well
Dealer

Posts: 223
Joined: March 4, 2013
 I guess that heating and bending resistors might influence noice, once
measured they might get more or less noicy after mounting and soldering.

Carbincomp is good! Metalfilm is for digitals.

 

RE: Why bother when the answer is already known?, posted on November 17, 2014 at 15:00:42
Russ57
Audiophile

Posts: 3754
Location: South Florida
Joined: November 16, 2001
 Far and away....bulk metal foil is your best bet....assuming it is noise you are concerned with. The next best is wirewound but now inductance becomes a major issue (perhaps).

Now that doesn't mean that you will like the sound of a bulk metal foil resistor best. Truth be told a little "distortion" can be a good thing in the right place/time:)

 

RE: Why bother when the answer is already known?, posted on November 19, 2014 at 08:15:40
Hornlover
Manufacturer

Posts: 2529
Joined: March 8, 2002
 '..Truth be told a little "distortion" can be a good thing in the right place/time'...

No, its never good. If you care about music, anyway. Now I will hear it from the SET loving crowd. If you want to add distortion, then make musical instruments. If you want to honor the music, the less distortion, the better.

 

Page processed in 0.032 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]