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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IME premium fuses make a very audible difference. If you don't hear an improvement, so be it, at least you actually tried it. You did try it, right?
Unfortunately Boxer, Georgie is on record as categoricaly stating he has NEVER tried a boutique fuse and NEVER will.

Now that is just a perfect example of a closed mindset.
I truly do not see what he has to gain by even posting on these types of threads as he has no interest in the betterment of audio enjoyment by said tweaks.

It grieves me to see such discord between fellow audio enthusiasts tbh.
NEVER tried a boutique fuse and NEVER will.

For your YELLING posting info, no I’ve never tried it, and no need to, but at my friends place for a day session with three others where he tried an SR Blue 3.15A fuse in his Gryphon Diablo 300, the fuse was taken in and out 3 x, even turned around once, not one out of the 5 of us could tell what was in compared to the original 3A, the owner "thought" he detected something on one of the occasions, but couldn’t be sure.
I am glad to read georgehihi6 post. I hope all who have experimented with listening to a same piece of equipment with different fuses will report their findings. I especially hope Pass Labs amplifier users will participate. 

georgehifi6 - do you know what brand fuse Gryphon uses? I think that is also interesting. Pass Labs uses Schurter Brand.

Wayne Colburn (Pass Labs) did tell me that their amps with circuit breakers have more circuitry in the signal path than those with fuse protection. I think amplifier design and implementation of a design is a fascinating area of the audio hobby.

Some  tube amplifier builders do keep track of wire directionally  such as the builder of the SET amp- Serious Audio. In these low  part count amps, perhaps wire direction can be more easily heard? I have read where SET amp builders will audition many brands of each part used before the product goes to market.

David Pritchard
georgehifi6 - do you know what brand fuse Gryphon uses? I think that is also interesting. Pass Labs uses Schurter Brand.
Yes I did ask to look at it, it looked just like a 50c Bussmann fuse like this, and my mistake they were 6.3A not 3A
https://ibb.co/QnZVtn5
Props Dave for all the extra work you put in on this. If your ears are half as good as I think they are then you knew in no time flat. I mean in took me all of 30 seconds to know a) its better and b) its backwards. Pretty amazing when something is so good you can tell its backwards within a minute and on first listen. And I'm talking Blue, which by all accounts is the biggest generational improvement yet. 

So you had to have had about as much uncertainty as me, which is zero, nada, zip, none, and yet you dutifully went back and forth anyway. For all the appreciation it got you. Oh well. At least it hasn't gone completely unnoticed.