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

128x128davidpritchard
@David Pritchard. Can you post which way the fuse sounds better? On the Pass Labs, which end goes in first? Don't know, but would it be possible to post a picture? I just got an orange fuse for my X-150.8 and if somebody can just tell me which way is the right way, that would be awesome.
Thank you.
What Peter can't you tell???? The other fusers, will be up in arms.

THERE IS NO RIGHT WAY. (it an ac mains fuse, mains alternates direction "60 times in a second" you'd have to pull it in and out and reverse it at the same rate to see if it's directional 😵)

Cheers George
@David Pritchard. Can you post which way the fuse sounds better? On the Pass Labs, which end goes in first? Don't know, but would it be possible to post a picture? I just got an orange fuse for my X-150.8 and if somebody can just tell me which way is the right way, that would be awesome.
Thank you.

You really should listen to it, because it really does sound better one way than another, and then you will know. Also then you can come back here and say hey guys you were right, it really does sound better one way than the other! And george will have one more in the mountain of evidence to deny and deride and ignore. But more importantly you will no longer be one of these parrots repeating stuff other parrots squawked about, you won't be a bird brain like George either, you will be one of us wise old owl types that KNOWS these things are directional. 

 us wise old owl types that KNOWS these things are directional.
Yep, a one way brain, can't see the forest for the trees.