Pass Labs and Fuses


I continue to enjoy my Pass Labs Int-60 amplifier with my horn based system. My listening area has been intensively treated for acoustic - speaker interaction and it is always a joy for me to listen to a Dialed In system.

For my latest listening experiment I decided to evaluate the sonic differences using three fuses in the Pass amplifier. A brand new Bussman fuse, a Synergistic Research Blue fuse and a Synergistic Research Orange fuse. I keep this amp on 24/7 as suggested by the manufacturer. The Blue fuse has over a 1000 hours on it and the Orange had a 160 hours (continuous playing time) on it before any listening evaluations. The Bussman was listened to for the first time immediately out of the box.

The Bussman fuse did a fine job. But going from the Blue fuse which I had been using to the Bussman, there was a definite change. With the Bussman the sound was now more two dimensional. Instruments were not as full bodied. The depth of the soundstage was compressed front to back. I was more aware that I was listening to a recording versus being in the room with the musicians. The music was less emotionally involving. I did for completeness sake reverse the direction of the new Bussman fuse several times. It did consistently sound better installed in one direction, not huge but it is there.

Comparing the Synergistic Blue Fuse to Orange Fuse was similar to my past tube rolling experiences with my 300B tubed amplifier (but cheaper to carry out). Different tubes change the sound and these different fuses change the sound. Both of these fuses brought out more of the music that the Pass Labs amp was playing when compared to the Bussman fuse. Before any serious listening was undertaken, the fuses were evaluated for best sounding direction - and they both were directional.

The Orange fuse really is exceptional in it’s ability to let me enjoy the music and who is playing what. The detail of Willie Nelson’s nylon strings on his guitar had much better dynamics and richer texture than I have previously heard using the Blue fuse. His Stardust album continues to impress me.

When listening to music that has more musicians playing, such as on Sierra Una Noche, I can more easily distinguish each instrument and it’s contribution to the musical whole. Also in this live recording that uses only two mics, I get a better feel of each musician’s distance from the microphones and that they move toward and away from the microphones while playing. These factors allow me to forget I am listening to a recording of an event. With the Orange fuse, I feel I am at the event as it is playing.

This fuse experiment was fun to do and educational.
Feel free to call.

David Pritchard
575-644-1462

8261cb9a ba3b 4423 9e13 73ca5a2da622davidpritchard
Too funny!

Here I was reading this great post admiring the thoroughness and the writing and not really thinking too much besides man I really need to upgrade my Blues but not much else until I get to the end and see....
davidpritchard.

Lol! Where you been dude? Well done. As usual.
On the rest of his amps Mr Pass was kind enough to use no fuses.  

On the rest of his amps Mr Pass was kind enough to use no fuses.
If not he probably used fuse-able links, many do these days and they look like resistors and usually stand proud of the boards some are even smd. Or he could have used circuit breakers, no voodoo fuses.

Cheers George
On the rest of his amps Mr Pass was kind enough to use no fuses.


Seems like that would be doing us a favor- or does it?

Only if the wire can be shown to sound better than the fuse.

Not likely.
One assumes he uses circuit breakers now because he found stock fuses to sound rather bad. I’m still trying to figure out what “stand proud of the boards” means. Is that an Aussie military expression? 😳
@davidpritchard  Thanks for your report on the fuses with your Pass amp.
“stand proud of the boards”
 stands off the board so when it fries it doesn't blacken the board with burn marks.

New English dictionary.
" 5. ADJECTIVE [ADJECTIVE after verb]If one object stands proud of another object that it is attached to or next to, it extends beyond it.  "cretin"
"only if the wire can be shown to sound better than the fuse".    ?????

Fuses are a choke point, the best fuse is no fuse.   Should I infer that the purpose of a fuse is not for protection but rather to somehow enhance the sound?

Post removed 

shannere
”only if the wire can be shown to sound better than the fuse". ?????

Fuses are a choke point, the best fuse is no fuse. Should I infer that the purpose of a fuse is not for protection but rather to somehow enhance the sound?

>>>>Uh, no. That’s just another variation of the “all amplifiers sound the same” argument.
On the rest of his amps Mr Pass was kind enough to use no fuses.
Pass uses fuses on their lower powered amps and breakers on their higher power
+1 for davidpritchard. I got the SR Blue Fuse on my Pass XA30.8 andthe improvement over the stock fuse was significant. More resolution and air with a smoother sound. I now have the Blue fuses on my preamp and cd player with similar results. One of the best bang for the buck upgrades I have done.
Pass uses fuses on their lower powered amps and breakers on their higher power
Yes normal quality industry standard $2 fuses, no voodoo fuses for Mr Pass. 
Cheers George
It seems odd that Mr. Pass is deaf. Well, shut my mouth and call me corn pone! 🤗
Nelson Pass and Roger Modjeski (Music Reference) are two designers responsible for some of the best sounding amplification available today, and neither "believes" in fuses having a sound. What a coincidence. I guess that their designs sound good is just a happy accident ;-) . Pretty good for two deaf guys.
It’s a cry in’ shame 😭 those two guys don’t believe in fuses or wire directionality 🔛 Otherwise their amplifiers would have sounded even better, no? Well, half of them would. 😛 And they would have sold more amplifiers. Too bad those two guys are so stubborn. They’re probably not good listeners. 😁

No matter how much you have in the end 🔜 you would have had even more if you had started out with more. - Old audiophile axiom
Fuses simply do not have a "sound" as they're not designed to...it doesn't matter how many hyperbole festooned claims of their sonic influence are written...they just can't and don't and will never do anything except wait patiently for something to cause them to blow. If spending 150 bucks to massage an expectation bias makes somebody feel better, it doesn't change the fact that fuses are simply fuses, a fact that yeah, designers like Nelson Pass (who seems to be into every single little tonal aspect of his designs and is actively involved with the audio geek community...not likely to miss out on the Magic of Special Fuses if they were an actual thing) know all about.
bdp24
Nelson Pass and Roger Modjeski (Music Reference) are two designers responsible for some of the best sounding amplification available today, and neither "believes" in fuses having a sound. What a coincidence.

geoffkait
It’s a cry in’ shame 😭 those two guys don’t believe in fuses or wire directionality 🔛  Too bad those two guys are so stubborn. They’re probably not good listeners. 😁

That’s why they are "Nelson Pass" and "Roger Modjeski", and you are __(pause)__well, Geoff Kait??, snake oil peddler https://ibb.co/YcrfSsM

I do appreciate all input about Pass Labs amplifiers and possible changes that might or might not affect their sound. I also found it very interesting that reversing the direction of an ordinary brand new Bussman fuse several times did consistently affect the sound I heard.

I own three Pass Lab amplifiers and like many audiophiles I respect what Nelson and his main co-designer Wayne do.
David Pritchard
@davidpritchard I have used a Blue Fuse in my Pass XP-20 preamp. It was easy to choose direction and, when in the correct direction, contributed to superior performance versus the stock fuse (which was also checked for direction and removed and reinserted as a check).
I do hope many who read this thread will go to " You Tube " and type in "Nelson Pass". Watch several of those videos and I think you will get a fabulous insight as to what most interests him, what he tries to achieve in a design, the trade offs he has to make, the parts he uses, etc.

I am not aware of a designer - manufacturer who is more open about his approach to audio amplifiers.
David Pritchard
David, you hit it right on the head,”less emotionally involving.”
Although I do not own one at this time, Mr Pass makes some of the best sounding amps. I think Beethoven proved that you don’t have to be able to hear, you just have to know what you are doing.
Some days my system sounds killer, other days not as good even with the same recording. The only things that have changed are the humidity and the barometric pressure. The real culprit is my state of mind, happy vs pissed off. If there is just one neuron in your brain that thinks something is going to sound better, it will. This does not mean that there are not meaningful changes you can make, there are. In my experience there is always a sound reason why something sounds better. In the case of the fuses there is not one. I use to bypass all the fuses in my system including speaker fuses. Then I started doing AB experiments with fuses, wire and switches. There was a slight improvement in bass bypassing speaker fuses. Otherwise the differences were hard to appreciate. I also always have a second set of ears participating. It would be better to have 100 sets but it would be hard to arrange for obvious reasons.
In most cases you are better off buying more music. 
I have used a Blue Fuse in my Pass XP-20 preamp. It was easy to choose direction and, when in the correct direction, contributed to superior performance versus the stock fuse (which was also checked for direction and removed and reinserted as a check).
How is it that one way it sounds better than the other-way??
When the AC (clue here "alternating current") is changing it direction 60 x a second?? You would have to be changing the fuse direction also 60 x a second to prove what you said that it "it sounds better one way than the other".
Post removed 
On "You Tube there is a six part interview with Nelson Pass. I found it fascinating. He has been experimenting with solid state designs for over 40 years. But it is important to know he is not the only designer at Pass Labs.
 
First Watt 7 amp - Nelson Pass primary designer
Pass Labs INT-60 Wayne Colburn primary designer
Pass Labs HP-1 Jam Somasundram primary designer

I am fortunate to have an example of each designers work.
Wayne Colburn has been designing at Pass Labs for 31 years!

A few quotes from Nelson on why there is more than one product sold and why he has been doing this for 40+ years. "What interests me most about amplifiers are the differences in sound created by different topologies". He creates amplifiers that create a "sound which has a particular signature".

In a You Tube video from 2016 there are shots of many Pass Labs products with their sides and lids removed to show the inside layouts and parts used. On purpose there is a high commonality of parts used to decrease variables. Nelson collects and stockpiles different transistors for possible future products whether they be Pass Labs products, First Watt products, or as a diagram released to the DYI community. Showing just one parts bin, Nelson estimated he had 250,000 examples of that chip.

He will run out of time on Earth before he runs out of different chips to evaluate.

I have also admired audiophiles who post results of evaluating the sonic changes using different capacitors of the same value in a piece of equipment. Tedious, time consuming, and requires excellent soldering skills (which I do not have).

I have enjoyed tube rolling in amplifiers for years. I have a large collection of the same type of tube made by different companies, that vary in age from new to 70+ years old. I do not find the sound to be dramatically different except my emotional response can be dramatically different. With some tubes I get a "That's the sound I want ! " I find that moment exciting and worth the effort in time and money.

I have also experienced the same satisfaction trying different fuses in the same piece of equipment. I now have 11 different fuses of the same value that I have listened carefully to. It is very time consuming and tedious but I find it satisfying.

 I work hard at minimizing any variables. My house is kept at the same temperature, the humidity is kept exactly at 37%, listening is always done at the same time of day (8:00 to 10:00 pm ), a record is kept of how long the fuse has been in the equipment, which direction installed, and the same music is used for evaluation. Written notes are kept to refer as a record.

On occasion I have read people asking the question about possible sonic changes heard using different fuses. I try my best to report my experiences listening to different fuses so others may use them as a data point of reference.

 As in Vacuum Tube rolling or Capacitor swapping, others may not hear a difference between different fuses or may come to a different conclusion to the quality of the change in sound.

David Pritchard

Tubes and capacitors are not fuses, not even close, and tube swapping (I don't change capacitors unless some malfunction has occurred, or, as in the case of a 60 year old tube guitar amp, they leak) results in interesting and obvious tonal changes. Fuses do not, and claims that "improper" fuse direction will make a component sound out of phase or otherwise compromised is silly and not an actual thing regardless of how many amps one has owned or how carefully somebody keeps track of this silliness, or how much carefully worded hyperbole is generated to shill for SR.
"How is it that one way it sounds better than the other-way??...."

georgehifi,

I agree with you that fuse direction loses all meaning in an alternating current (AC) application.
or how much carefully worded hyperbole is generated to shill for SR.
+1 Wolf, he’s taken over from oregonpapa, who was slapped on the wrist for doing it.

I agree with you that fuse direction loses all meaning in an alternating current (AC) application.
Yes this **** about fuses is just snake oil voodoo speak and it’s dangerouse for the gullible non-technical to be playing around with, and needs it’s own place, maybe here at geoff’s website. 
http://www.machinadynamica.com/machina31.htm
Where he and david can get sued if someone gets zapped, in there feverish attempts to hear differences when fuses are turned around, forgetting to turn/unplug from the mains.

Cheers George

Hi all, I almost never post but after many years of reading how some people say fuses don't make a difference or are not "directional" here are the facts they Do measure differently in either direction! also to those who don't believe they impact the sound of a piece of equipment read the measurements again they all measure differently...
I have tried fuses from 5  manufactures over the last 10 years and they all sound different and are directional.
Kind of amusing that people who have never tried fuses bash the concept like their life depends on it I just don't get it, and probably never will...
Please feel free to pass this link on to the other threads for the nonbelievers, the numbers and my ears don't lie.
Enjoy
Http://www.hifi-tuning.com/pdf/wlfr.eng.pdf
To some people it is more important to think they are right than to experience and learn something.  Know it alls don’t accept things they may not understand.  
@tommyu 

@nutella 

x2

BTW, I’ve never tried fuses, but like all things audio, I expect they can and do have an effect on sound. People shouldn’t have such an aversion to trying it for themselves. I’ll get around to it myself some day.

Modjeski actually did find the Tuning Fuse he tested measured differently than the Little Fuse brand he routinely uses. The difference was on the order of 120dB down ;-) . If your system can reveal that, and your ears can hear it, congratulations, you do indeed have a mighty fine system and golden ears.

Yeah, I know not everything that can he heard can be measured. But for a fuse to effect the tonality of a system? C'mon, man, you know that's not possible. A fuse doesn't know about tone, any more than an acoustical instrument knows about electricity.

As for fuse directionality in an AC application, that defies what used to be called common sense. Yeah I know, what about all the people who insist to hear a difference when the fuse is reversed? I have no idea (mechanical issues perhaps), but people also claim to hear God talking to them. Do you?

That’s precisely what wrong with the “measurement is everything” approach. Even HiFi Tuning admits the relatively small measured differences don’t account for the relatively large differences in fuses and direction of fuses heard in listening tests. Oh, well, that’s the way it goes sometimes. It looks like it’s Modjeski’s opinion vs 90,000 aftermarket fuse users. No one really knows why cables sound so different yet measure the same, either, or sound so different in one direction vs the other. This not something new under the sun, anyway. Modjeski is a few paradigm shifts behind the power curve. The only debate about fuses and cables and power cords is in the mind of the dyed-in-the-wool skeptic.
Modjeski is a few paradigm shifts behind the power curve.
NOW!! that's rich, coming from you. https://youtu.be/YTY26k0CA0I?t=5
It's as if Ted Denny or his marketing department at SR puts out a signal to the sales force that they're overstocked with the fuses....which likely cost about eighty cents to produce including the orange paint. Get some cash flowing into the snake pit!

Yeah this is definitely one that should be in the "scammers" forum, along with SR-HTF's, Bybee Quantum Purifiers .
And let's not forget the daddy of all voodoo snake oil crap, all those years ago the:  
"Shun Mook Mpingo Disc" from decades ago that started the "Audio voodoo snake-oil revolution"

Cheers George
I’m very disappointed Georgie Boy that you didn’t pick my Clever Lil Clock or Teleportation Tweak as your daddy of all voodoo snake oil crap. 😢 The Mpingo Disc is obviously just ordinary physics. Can I suggest a physics refresher for high schoolers?
Most people do not try anything they criticize. They merely state an opinion of incredulity.

Fro me, I like measurements. If something is manufactured it can be measured. Your point about directionality can be measured for example. I do not doubt this.  If I can hear a difference is what much of this hobby is about once we get into the esoteric end of it.  So, I usually ignore tweaks without measurements because extravagant claims can be made about anything.  Finally, if I can hear a positive difference it might be worth pursuing and comparing.

I do not like to fiddle with the internals of anything. I did not like taking my Wadia 27i apart just to adjust the sensitivity. However, that is me, and I can have no informed opinion about the efficacy of fuses. I do not doubt they make a difference, to some.  I may not be as sensitive to these tweaks as them though. If you are happy that is all that matters.
I’m very disappointed Georgie Boy
I’m shattered, that a snake oiler is disappointed in me.

What do you call this your selling to the same gullible fusers for $129
http://www.machinadynamica.com/machina31.htm
and these 
http://www.machinadynamica.com/machina62.htm
http://www.machinadynamica.com/machina47.htm
and many other BS voodoo c**p
Oops a daisy! You got me there. 

Modjeski actually did find the Tuning Fuse he tested measured differently than the Little Fuse brand he routinely uses. The difference was on the order of 120dB down ;-) . If your system can reveal that, and your ears can hear it, congratulations, you do indeed have a mighty fine system and golden ears.

Yeah, I know not everything that can he heard can be measured. But for a fuse to effect the tonality of a system? C'mon, man, you know that's not possible. A fuse doesn't know about tone, any more than an acoustical instrument knows about electricity.

As for fuse directionality in an AC application, that defies what used to be called common sense. Yeah I know, what about all the people who insist to hear a difference when the fuse is reversed? I have no idea (mechanical issues perhaps), but people also claim to hear God talking to them. Do you?

I must say I am a little surprised to read this Eric, I had thought you were more open minded than that?

A few years ago I could have penned that until a member here( who does not list any longer unfortunately) sent me a SR Black fuse he had replaced with a Blue fuse in his dac.
I had the exact same dac.
First try I was not impressed, it really was no better and if anything worse.
Try it the other way he said.
After I got up off the floor from laughing I though oh well why not!

Say what?!?!
Who swapped my dac for a much more expensive model!
I have been open minded and receptive of tweaks ever since.

And yes George and Wolf you can run your normal belittling routines.
It's not going to have any effect on those who hear a difference.
What in heaven’s name was Modjeski measuring that was -120 dB down? -120 dB is below the noise floor of many, if not most, electronics. Cut me some slack, Jack! HiFi Tuning measured voltage drop in milli ohms. Which makes some sense, anyway. Even though they screwed up the percentage differences. 
Same old die hard fuser’s magic circle club, nothing has changed, except for their "Team Leader", oregonpapa who was wrist slapped and had threads closed for, well, you guess and make up your own mind.
Same old haters, nothing has changed.
Except possibly a little more desperate....
You can’t teach an old dog new tricks. 🦴 🐕 Fido, fetch!!


@uberwaltz,I brought up the opinions of Pass and Modjeski regarding fuses only as an intellectual exercise, for the sake of discussion. I like to hear opposing opinions on subjects, and don’t necessarily have to agree with one I cite (some consider that a cop-out. I don’t.).

I find it interesting when a designer who doesn’t "believe" in the audible superiority of certain boutique parts in all applications produces a product found to provide higher sound quality than those of a designer who does. Is that superior sq the result of design knowledge and wisdom, or merely a happy accident? I mean, if, say, Roger (or Nelson, or anyone else you care to name) can’t hear the difference between garden-variety and "audiophile" fuses, is the superior sound quality of his products achieved because he knows what good sound is---and what design choices lead to that superiority, or in spite of not knowing what doesn’t?

I myself have no opinion on the audibility of fuses (the used ARC PH3 I bought came with both a stock fuse and a Tuning Fuse, but I never A/B’ed them---I didn’t have the PH3 for very long), but do heed Modjeski’s warning about using the Tuning Fuse in a tube power amp. By the way, when I had Ric Schultz (of Electronic Visionary Systems, or EVS) modify my Audible Illusions Modulus 2 pre-amp into a phono-only RIAA amp, I took him up on his offer to bypass the fuse, a thought that now horrifies me!

Here is something I found interesting (hope you do too ;-): In a discussion on his Music Reference AudioCircle Forum on the subject of bass traps, Modjeski stated he was perplexed as to why anyone would spend money on subs, then spend more on bass traps to get rid of the bass they produce. In a flash, I realized that in spite of his vast knowledge of amplifier design, vacuum tubes, and many other hi-fi matters, Roger was not well-versed in matters concerning room acoustics. Bass traps are used not to suck up the bass produced by subs (or woofers in general), but rather the standing waves created by listening room dimensions (modes).

I do admit that when it is said a fuse changed the perceived tonal balance or other timbre-related issue, I find that claim extremely unlikely, if not impossible. How could a fuse possibly be frequency-related (other than 60Hz, etc.)? That just completely defies common sense and rationality. I also consider a fuse in an AC signal to obviously be bi-directional. How could it not be?!


One thing I've noticed is, there is a lot of opinions on the efficacy of fuses and only those who have tried them hear a difference, save for one or two that I can recall. 

What does that make of the validity of those who haven't tried?

All the best,
Nonoise
Whenever someone hears a difference or thinks something sounds better its still just an opinion. Anybody can have one. It’s still only one opinion no matter how many times it is asserted. 
That's like saying an actual witness to an event has no more credibility than one who hasn't. It's a word game now, and has been for a great while.

All the best,
Nonoise