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

The new SR Orange fuses are doing just fine in my system at the moment. They have provided more clarity, better dynamics, and more realism overall.

They put this lady in the room front and center:

Highly recommended.

I have enjoyed my experiment to see if three different fuses would affect the sound in my Pass Labs INT-60 amplifier. To my brain they did.

My next experiment will simplify things a a bit more. Today I ordered the Nelson Pass First Watt SIT-3 amplifier. This will be compared to the First Watt F-7 using stock fuses and boutique fuses. So two similar very low part count and simple circuit amplifiers will be used to compare the difference between two different type.output transistors. Then stock and boutique fuses will be tried in both. 

The SIT-3 amplifier arrives this Friday.

The test will be partially blinded in that my Mother will be the listener and she is legally blind. The new amp if she likes it, is her Christmas present.

This will be fun.
David Pritchard MD
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...
This thread, needs to be shut down, it's turned toxic just like all other fuse threads have. None, not one, especially SR fuse manufacturers have come onto these forums to stand up to what BS they (and the magic circle club) say these fuses can do
And it's very dangerous for non technical to be playing around with ac mains fuses, and trying them in different directions frantically, forgetting just once to unplug mains before touching the fuse. 

Cheers George