Resistors

rollo · « **on:** 23 Nov 2009, 03:21 pm »

Well I read a lot about the difference in sonics when it comes to caps. What about resistors? Would say a metal film such as Vishay sound any different than a metal oxide or carbon based ? Is it more important to have resistors that are 1% matched as oppossed to material of such or both ?
I would like to change the resistors in my amp which connect to the tube socket pins. Am I wasting my time or will a so called better resistor pay off in sonics ?

charles

nullspace · « **Reply #1 on:** 23 Nov 2009, 04:17 pm »

I generally think that specific types of materials do best in specific applications. Here's something I cribbed from Paul Joppa of Bottlehead:

Quote

Carbon composition is the best for low inductance, which is important in grid stoppers which are effective at hundreds of MHz. They are noisy, but only if they have DC current through them, and the noise is proportional to the resistance. So as grid stoppers (no current) and as plate stoppers (small resistance, and located after the first signal amplification stage so that noise is 30dB less important) they are OK. In both applications, drift of the resistance is not important.

Plate resistors are usually metal film, which is generally very quiet even with DC current, and they are also readily available in 1% or better precision. They do have a bit of inductance, but it's not significant at audio frequencies. We also use them in the RIAA equalization network, where precision and low noise are important. We avoid them when small amounts of inductance are important.

Wirewound is the quietest, but usually has the most inductance. We us them in power supplies where the small inductance helps isolate diode switching transients and power line RFI noise.

Metal oxide is noisy and usually imprecise, but they are very sturdy (withstand voltage transients and momentary overloads without damage) so they make good power supply bleeders where the large parallel capacitance can shunt the noise to ground.

Further, tolerance is also more or less important depending on application. In a RIAA section, 0.1% is appropriate, but for plate loads and cathode bias, not as important.

If you could post a schematic for your amp, we could give you specific recommendations on upgrading resistors.

Regards,
John

BobM · « **Reply #2 on:** 23 Nov 2009, 04:48 pm »

Yeah, resistors can make a difference, but not across the board. It may make more sense to identify a key resistor in the signal path and replace it with a nude Vishay rather than just putting Riken Ohms everywhere. That's where a designer who believes in boutique parts can work their magic, as compared to a designer who is an engineer only focused on design principles and cost constraints.

shep · « **Reply #3 on:** 23 Nov 2009, 06:16 pm »

The above is sound advice. If you have say a resistor-based, stepped ladder-type potentiometer, you will hear the difference between say Vishay and Shinko or Caddock. In other places the issue is more about how the circuit operates and is somewhat less critical sound-wise.

turkey · « **Reply #4 on:** 23 Nov 2009, 07:06 pm »

The other point of view is that things like caps and resistors don't really have a "sound" as such. There are different types of each, and they are suited for different purposes.

rollo · « **Reply #5 on:** 9 Dec 2009, 04:22 pm »

thanks for the input men. The resistors in question are located at the tube sockets.

charles

Pez · « **Reply #6 on:** 9 Dec 2009, 05:23 pm »

Quote from: BobM on 23 Nov 2009, 04:48 pm

Yeah, resistors can make a difference, but not across the board.

So don't solder your resistors across the board?

Since the flavor of the week seems to be arguing about uber-boutique audio parts here's one that I found for you, top of the line resistors!

http://www.caddock.com/

Bill Baker · « **Reply #7 on:** 9 Dec 2009, 07:03 pm »

rather than getting into a discussion about what resistors sound better, the more important thing to consider is using the proper resistor for the application. Going by general rule, you want carbon for the grid stop, non-inductive for cathode and so on. You also want to look at the resistors at the input of the circuit. The first resistor the signal sees is critical to me as this is where noise levels are effected. Wirewounds such as Mills or vishays will be the quietest but others will have different opinions.

Just a few thoughts from my 2 brain cells.

rollo · « **Reply #8 on:** 9 Dec 2009, 07:54 pm »

Thanks Bil. So you were at Woodstock as well ? Together we have 4 brain cells. Brilliant!!

charles

serengetiplains · « **Reply #9 on:** 11 Dec 2009, 07:06 am »

My advice? Use the lowest-noise resistors you can get your hands on. I personally prefer nude Vishay Zs:

http://www.texascomponents.com/

Click around this website until you find "Audio Resistors." Z-foils are it.

Steve · « **Reply #10 on:** 15 Dec 2009, 11:39 pm »

Quote from: rollo on 9 Dec 2009, 04:22 pm

thanks for the input men. The resistors in question are located at the tube sockets.

charles

Yes Charles, as mentioned above resistors do make a sonic difference. Plate, grid, cathode resistors need to be checked VS not only the design but also VS capacitors used etc.

For instance, if a "dark" sounding capacitor is used with "dark" sounding resistors, the sound will be influenced. Conversely, if a bright sounding capacitor is used with a "sparkly" sounding resistor, the sound could be fatigueing.

Hope this helps.

Telstar · « **Reply #11 on:** 16 Dec 2009, 12:45 pm »

Quote from: serengetiplains on 11 Dec 2009, 07:06 am

My advice? Use the lowest-noise resistors you can get your hands on. I personally prefer nude Vishay Zs:

http://www.texascomponents.com/

Click around this website until you find "Audio Resistors." Z-foils are it.

Do you know the prices? i'm definitely going to use some of these in the OPS of a new power amp.

rollo · « **Reply #12 on:** 16 Dec 2009, 03:35 pm »

Again fellow members thanks for the help.

charles

serengetiplains · « **Reply #13 on:** 18 Dec 2009, 03:36 am »

Quote from: Telstar on 16 Dec 2009, 12:45 pm

Do you know the prices? i'm definitely going to use some of these in the OPS of a new power amp.

$10 a piece for the new Z resistors. Price increases above 50K resistance.

rollo · « **Reply #14 on:** 17 Jan 2010, 03:50 pm »

Quote from: Steve on 15 Dec 2009, 11:39 pm

Yes Charles, as mentioned above resistors do make a sonic difference. Plate, grid, cathode resistors need to be checked VS not only the design but also VS capacitors used etc.

For instance, if a "dark" sounding capacitor is used with "dark" sounding resistors, the sound will be influenced. Conversely, if a bright sounding capacitor is used with a "sparkly" sounding resistor, the sound could be fatigueing.

Hope this helps.

Thanks Steve. The coupling caps installed are V-cap teflon. The resistors in question are connecte to the tube socket and then a terminal strip. Same as caps. I wil be using Panasonic TScaps in the power supply. I've chosen Takman RX carbon film resistors or Riedon for the signal path with Rikens for the grid. How am I doing so far ?

charles

Occam · « **Reply #15 on:** 17 Jan 2010, 05:54 pm »

For those seeking carbon film resistors at less than bespoke prices, consider the KOA/Speer SPR caps available from Mouser.
http://mouser.com/KOA-Speer/Passive-Components/Resistors/Power-Resistors/_/N-2gra1Z1z0zlrr?Keyword=spr&FS=True
I cannot differentiate between these and Kiwames.

JoshK · « **Reply #16 on:** 17 Jan 2010, 06:19 pm »

I've used those KOA/Speer CF resistors in a lot of my tube projects. I didn't do any comparisons, but they get good recs from the diy crowd.

rollo · « **Reply #17 on:** 19 Jan 2010, 03:28 pm »

Thanks for the Link paul.

charles

BobM · « **Reply #18 on:** 9 Mar 2010, 02:10 pm »

I tried some rather special resistors in some key spots on my Hagerman Piccolo step up. I built the whole board with Dale/Vishay bulk metal foil's However I had some generic Digikey metal foils laying around for some values so I used those in a few places where I could.

One place I used those happened to be in a fairly key location, where it was directly in the signal path. The sound was a little hard and edgy to my ears so I began looking a little deeper. There are actually 2 resistors directly in the signal path that could be upgraded.

I got some Vishay nude resistors for both spots and replaced them. The sound immediately opened up a little more and that metallic "ting" was gone. Very nice improvement, but still not completely musical. So I also ordered a pair of Riken Ohms from Partsconnexion for one of the locations. I've read that these can add a touch of warmth and bloom to the sound if used judiciously. If over used things can get muddy.

So I kept the nude Vishay in the one position and replaced the other with the Riken. After about 4 sides of vinyl the initial haze burnt off and there was bloom and warmth and extension and musicality again.

So yes, I do believe that resistors can have a sound and can be used to tune a system and that it is worthwhile to look over a circuit and put in higher quality parts in key locations.

I've also heard similar results using those Caddock white paddle-like resistors in a signal path. Very open, musical and involving.

Enjoy,
Bob

rollo · « **Reply #19 on:** 9 Mar 2010, 03:46 pm »

Chose matched 2% tolerance Kiwame and Takam for the amp upgrade. Over the stock metal oxide resistors NO comparison. A major improvement all around.

charles