Hi-Fi Tunig Fuses & Parasound A21

@toolbox149
I have replaced both the main and the 4 rail stock fuses of my Parasound A21 amplifier with Hifi tuning fuses. I replaced these fuses in sequence. First replaced only the main fuse by Hifi Tuning Silverstar fuse and it immediately improved the sound in all areas. What I liked the most is the blacker background and the improved clarity. Not sure how it dropped the noise floor but it did.
Then I replaced all 4 rail fuses with Hifi Tuning Gold fuses (couldn't get the Silverstar in 8A rating) with the arrow pointing to the flow of the current i.e pointing from the transformer to the capacitor. The result wasn't so impressive. While it further increased the clarity but the instruments started sounding very hazy and smeared. The overall sound was also veiled. It has been 20 odd hours since I replaced the internal fuses and they might still be going through the break-in interval. I tried flipping the fuses such that they point to the transformer to see if that resolves the haziness issue but it didn't.
Did you have similar experience when you replaced the rail fuses inside your amplifier? Did you find any break-in period with these fuses? Any feedback/help in this regard would be greatly appreciated.Thanks.

Like most anything that impacts the electrical circuit of a piece of kit, break-in is necessary. Obviously this requires patience, a virtue few of us in this hobby possess in abundance. I don’t have an electrical engineering degree that might help inform me as to why things in this quizzical hobby happen as they do but they do occur. There is plenty of anecdotal evidence of such all over this site. Perhaps the mystery is part of the appeal.

As far as Steve McCormack goes, I know what my stock amp sounded like and what it sounds like post SmC Audio mods. Nuff for me!

It took about 4 days for my HiFi Silverstar fuses to break in. I kept the amp on 24/7 and would turn up the volume now and then to get a handle on the sound. I still don't know or understand how anyone can hear an immediate improvement, but that's been my experience. By the way, I replaced all the fuses at the same time, if that helps to clarify anything.

All the best,
Nonoise

Indranil

Your experience is an exact replication of my results. The silver in the main was excellent but when I added the four golds in the rails, the overall sound was way too warm with a loss of upper mid-range detail for my tastes.  It was warm to the point of getting a little muddy.

I would recommend burning them in for at least 30 hours before you start making any decisions. Like I said above, whether your burning in tubes or fuses, after about 30 hours of burn in, you'll have a pretty darn good idea what they will ultimately sound like. 

If after 30 hours of burn in, you still don't like the sound, try replacing two of the gold fuses with your original fuses. So, each rail side L & R will have a gold fuse and an original fuse.  That sounded better to me.   Now I have a silver and a gold on each side of my rails, which is a very nice balance.  I see where you can't get silvers anymore, so hopefully the gold & original combo will work well for you.

If you somehow can get a couple of silvers, if possible I would only buy two and do a silver and a gold combo in each side of your rails.  Four silvers in the rails plus a silver in the main fuse might become too bright rendering details like female vocals and brass instruments a little harsh.  Too much of a good thing.

Do you have any tube equipment in your set-up?

Just remember it's not whether you have all of your fuses upgraded or half of your fuses upgraded.  If you like the resulting sound, you're the big winner!  So then just sit back and enjoy the music.

Toolbox

I don’t have an electrical engineering degree that might help inform me as to why things in this quizzical hobby happen as they do but they do occur. There is plenty of anecdotal evidence of such all over this site. Perhaps the mystery is part of the appeal.

Its the voltage drop across the fuse. You can hear it and measure it when the fuse is correct in its holder. Its easy to measure. If the fuse is on a circuit board, I find it more expedient to spin the fuse in its contacts until you see a lower voltage drop rather than reversing it.

The variable voltage drop caused by the fuses and fuse holders not being perfectly dimensioned is what has given rise to the idea that they are directional. They aren't (and can't be, if they were they could not be used in AC circuits); its just that sometimes when you reverse them you're getting a better connection. Its really that simple- no mystery and easy prove through measurement. If you want it to remain mysterious though, just don't measure the voltage drop across the fuse :)