What tweak are you carrying today?

microstrip

VIP/Donor
May 30, 2010
20,806
4,698
2,790
Portugal
Replacing the SoundLab A1 PX crossover power resistors with Vishay thick film ones. Bias expectation is high - it is a lot of work!
 

Attachments

  • a1.jpg
    a1.jpg
    421.5 KB · Views: 660

JackD201

WBF Founding Member
Apr 20, 2010
12,308
1,425
1,820
Manila, Philippines
That looks like more than just tweaking to me micro.
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
+1! Let us know how it goes!
 

Douger33

Well-Known Member
Jan 19, 2013
47
2
248
Omaha NE
Last week an audio friend alerted me to the charcoal tweak from Audio Direction in Honolulu... I put three charcoal bricquets on top of each of my Tannoy Canterbury's, on top of paper towels and toward the front. It is an organic thing, and totally reversible. I received good results...
 

garylkoh

WBF Technical Expert (Speakers & Audio Equipment)
Sep 6, 2010
5,599
225
1,190
Seattle, WA
www.genesisloudspeakers.com
Why are you using thick film resistors? Thick film resistors are oxide paste film. They have the most self-noise, worst tolerances, and high temperature coefficients.

Even thin film resistors have better temp coefficients and lower noise. They are made of a sputtered metallic nichrome film and in general sound a lot better.

In a loudspeaker, I would use wirewound with non-inductive Ayrton-Perry windings. The very best would be the Vishay metal film, but those are supremely expensive and difficult to get in the right values.

In some cases, I would use a carbon resistor for a different sonic characteristic.
 

microstrip

VIP/Donor
May 30, 2010
20,806
4,698
2,790
Portugal
Why are you using thick film resistors? Thick film resistors are oxide paste film. They have the most self-noise, worst tolerances, and high temperature coefficients.

Even thin film resistors have better temp coefficients and lower noise. They are made of a sputtered metallic nichrome film and in general sound a lot better.

In a loudspeaker, I would use wirewound with non-inductive Ayrton-Perry windings. The very best would be the Vishay metal film, but those are supremely expensive and difficult to get in the right values.

In some cases, I would use a carbon resistor for a different sonic characteristic.

Gary,

Thanks for the wise advice. I have used them because I saw SoundLab used them in their "HotRod" package. I have to say they were not my choice after the listening tests - the current winners are the Mundorf M-Resist Supreme (high power large wire ceramic resistor). As I use a lot of them in series/parallel I connect them minimizing the inductance reversing the sense of the currents along inline resistors. BTW , they are not used in serial - just in the bottom of a CR network.

Great to have the collaboration of experienced experts in WBF!
 

microstrip

VIP/Donor
May 30, 2010
20,806
4,698
2,790
Portugal
Try these: http://www.vishay.com/docs/31801/mra.pdf

Using a lot in series/parallel is not recommended. The reason is that you are then subject to a lot of different signal paths depending on the tolerance of each resistor.

Unfortunately they are rated at 10W - SoundLab uses resistors totalizing 100W in this position. Some users reported increase in sound quality using 200W.
Do you think that associating resistors in series should be better than in parallel? I checked the values and they match to .5%.
 

garylkoh

WBF Technical Expert (Speakers & Audio Equipment)
Sep 6, 2010
5,599
225
1,190
Seattle, WA
www.genesisloudspeakers.com
If they are not in series, and at the bottom of a CR shunt, then they would never be dissipating anywhere close to 100W. If they were, your amplifier would be driven to clipping at all times.

The reason that you would have huge power dissipation is due to the fact that thick film have bad temperature coefficients. In particular, thick film are prone to transient noise due to slow heat dissipation. Wirewound are a factor of 10 or more better for this job. I prefer associating them in series to parallel. However, as a shunt resistor below a capacitor, the phase effects of the capacitor swamps the resistor, so that should not matter as much. However, because it is in series with a capacitor, the lower the inductance (parallel) the better.
 

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. This is THE place where audiophiles and audio companies discuss vintage, contemporary and new audio products, music servers, music streamers, computer audio, digital-to-analog converters, turntables, phono stages, cartridges, reel-to-reel tape machines, speakers, headphones and tube and solid-state amplification. Founded in 2010 What’s Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals, we enjoy learning about new things and meeting new people, and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing