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

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Showing 7 responses by wolf_garcia

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.
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.
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!
In a few of my posts regarding fuse mythology I've asked the question, are all of the wires used in a component sorted for directionality? Wait...I think I know the answer: the answer is no. Moving on...Is the wiring in that jumble of direction chaos possibly self canceling as regards directionality advantage? If a fuse's directionality benefit meets wire (and PC board traces) installed in this random order of direction, how does reversing it (remember, it's generally a tiny little wire relative to the wiring and traces in the component) audibly help things? The likely answer could be "somehow it does" if you spend 150 bucks or so...and remember when reversing the fuse to its supposed audibly "phase correct" position, you should reverse and test all the wire and PC traces (!) in that component as hey, ya never know. Now get busy...
A couple of years ago I tested a pile of SR fuses just to give my ranting some credibility (!) and found they were useless and somewhat dangerous as their ratings were suspect. You can look it up...also, note that nobody responded to my previous post regarding internal wire direction chaos which, to my thinking anyway, negates fuse influence as described by the Athletic Supporters of fancy fuses. 
I'm still waiting for a response to my "wire direction chaos" post...it's almost as if nobody cares...*sniff*...and to address Kaitty's comment...yes, georghifi and I are the same person. Anybody got a problem with that?
Note to my alter ego George...I inspired Ted Denny to surface when I posted that I read someplace his fuses were made in China...he popped in to accuse me of "fake news"...creepy!