2. misc-audio
  3. 152636-1819

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
davidpritchard's avatar
davidpritchard OP
866 posts
 
I do hope  Audiogon will remove posts that resort to disrespect to other members. But I seriously hope that all posts remain on this thread that are written in a respectful manner , regardless of their agreeing or disagreeing with my observations . I see no reason to allow mob rule to shout down serious discussion about any audio topic.  I also welcome suggestions in improving my test approach.

 Tomorrow - Friday, the Pass Lab SIT-3 amplifier is scheduled to be delivered. Pass only made 250 of these units because the SIT transistor used is long out of production. Nelson is the sole designer of this unit and the F-7. I look forward to comparing this unique type of topology amp to the First Watt-7, and then to investigate any differences fuses and fuse direction makes.

David Pritchard
uberwaltz's avatar
uberwaltz
13,381 posts
 
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.
georgehifi's avatar
georgehifi
10,312 posts
 
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.
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
More to discover