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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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davidpritchard's avatar
davidpritchard OP
866 posts
 
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
georgehifi's avatar
georgehifi
10,312 posts
 
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
millercarbon's avatar
millercarbon
12,531 posts
 
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.
rbyington711's avatar
rbyington711
66 posts
 
David

I have never heard that Pass Labs suggests that you keep their Amps on 24/7. I have an old X250 would you recommend doing the same and why?

Please advise 
uberwaltz's avatar
uberwaltz
13,381 posts
 
George
Just as an FYI.
If my post had been all caps then yes that would have been a "yelling" post.
But when just one word is in caps it signifies a highlight of that one word ( or more than one in this instance) within said post.

Just wanted to clear that up as I was most definitely not yelling at you George, life is too short.

However I am interested in the Gryphon story as I do not think I have read that from you before and it is actually very relevant and thank you for that.

As I have clearly stated many times, if people have tried something and found no difference or change or even worse it made matters worse then that is what it is.
A result that they perceived they heard or not heard whichever the case may be.

So both yourself and Wolf have tried or been party to trying of aftermarket fuses and did not consider them a worthwhile sonic benefit.
That is perfectly fine and a report of what you discerned.

It does not of course mean they are a waste of money and do not work period, just they did not work for you guys at that time in those systems.
And you cannot say any more than that.

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