One of the two main fuses for BHK Amp 250 was listed as 12 amp. I would like to try Synergistic Research Black fuse, however, only 10 amp or 12.5 amp fuse is available. Which one should I use? Thanks for the advice.
Sometimes folks have gone with the SR black fuses in one size up.
In that case 12.5 amp rated should be fine.
I have the 2A and 10A SR black fuse set on my BHK250 (120V version) and they are great.
Now I have SR black fuses in my PS Audio DAC, BHK preamp and Amp 250. They really make a difference for the better, and are definitely directional.
Hey zheng4, which direction did you insert the fuses? With the bottom of the SR in the facing the back of the unit or the front?
The following is the direction I use for all the SR Black fuses in my PS Audio DAC, Preamp, and Amp, look at the SR letters on the fuse which are horizontal relative to the fuse long body, insert the R end into the fuse holder toward inside of the equipment. I initially inserted the other way around, not intentionally, just happened to be done that way. After I learned that the fuse might be directional, I reserved the direction, I liked it better. That was on DAC initially. I was still not convinced and wondering if there was any bias in my judgement. So I asked my wife to change the directions of the fuses in my Preamp and amp without telling me what she did initially, I can hear the difference and told her correctly what she did or didn’t do (she did say I am delusional!).
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But you are consistently delusional. 
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I think we’re all delusional . . . .
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My wife said I was absolutely delusional and cut off my spending money after I bought SR PowerCell 12 UEF SE 
.
Joking aside, I guess the essence of this is that SR black fuses are directional, you must try both directions. First I only had SR black fuse in my PSAudio DAC, I was not that impressed after a couple of hours of listening, thought maybe just need more burn-in, then after 100 hrs, still not sure why all the high praises I read online about this fuse. Then my delusional thought came in, and I reserved the direction of the fuse, now everything made sense. After I bought more SR black fuses for my BHK preamp and amp, I still experimented the direction with my wife’s help (see my post above). Maybe because of all the PS Audio components, maybe because of all of the fuses I received have the same direction, I ended up with all the fuses in one direction. I strongly advise people to try both directions for each your components, especially if your components not from the same brand.
Don’t have BHK but i’ve danced a bit with the SR black.
Make sure the music you are listening to is in the proper polarity before trying to pick the proper direction. Based on my experience if you are listening to music with inverse polarity you will have your fuse in the wrong orientation to compensate. The easiest way is to just email psaudio and get them in the correct direction and then if you still think it sounds funny… try inverting the polarity of the particular music you are demoing.
zheng4 saidThe following is the direction I use for all the SR Black fuses in my PS Audio DAC, Preamp, and Amp, look at the SR letters on the fuse which are horizontal relative to the fuse long body, insert the R end into the fuse holder toward inside of the equipment. I initially inserted the other way around, not intentionally, just happened to be done that way. After I learned that the fuse might be directional, I reserved the direction, I liked it better. That was on DAC initially. I was still not convinced and wondering if there was any bias in my judgement. So I asked my wife to change the directions of the fuses in my Preamp and amp without telling me what she did initially, I can hear the difference and told her correctly what she did or didn’t do (she did say I am delusional!).
You’re not delusional
I also rely on my wife to check my audio obsessions.
Just to be clear on the orientation, the 20mm fuse has the letter “SR” arranged horizontally. On the 32mm fuse, the “SR” is printed vertically on the left side. My Directstream and BHK amps use the 20mm Black fuses. I prefer the results when the fuses were inserted with the letter “S” closer to the rear panel. I think that this is the same direction as zheng4.
With my Pass XP-15, I prefer the 32mm fuse with the “SR” facing the inside of the chassis.
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Question here: I have a 120V BHK250.
The manual states that the the smallest fuse should be 1.6A but the back of my BHK says it should be 2A. Does anyone know what the correct fuse size should be? Or if just using the largest size gives sonic benefit?
Go for the 2A and 10A slow blow for the mains as the amp says. Looks like PS Audio manual is more accurate and maybe they changed values at some point? You are less likely to blow fuses if they are a tad bigger vs too small.
I haven´t changed 4 rail fuses yet,but I think today is a good day to order them. I have Hi-Fi Tuning Supreme3 cardas copper versions everywhere and now to decide should I get silvers to rails,hmmm 
or maybe 2 silvers and 2 coppers 
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I just ordered oranges for all my fuses. DSD DAC, PreAmp, BHK250, and p15 
Excellent choice 
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Yeah, it’s 2A for the 120V.
One thing you can try that I thought was a huge improvement that i have never been able to convince anyone else, is to also upgrade the BHK250’s rail fuses. When I upgraded mine the SR Black fuses were on sale (the Blue had just come out) so I got the SR Black for the power inputs but at $120 each that was too much for the four rails. So I just used the HiFiTuning Supreme (~$65) and that seemed more manageable, cost wise.
The improvement was noticeable on the main power fuses, but the new rail fuses made is sound like an entirely different amp. (I changed rail fuses first, then the main power fuses)
let me know if you experiment with them, but I thought it was a huge improvement, much more than the power input fuses themselves.
Best of luck!!
–SSW
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It’s interesting you say that the rail fuses made more of a difference. I too agree. I changed rails first, then I changed the other fuses. However, at the same time as the input fuses, I changed my DSD Jr and P15 fuses so it’s hard to say for sure. Waiting to get my preamp back from PS Audio then I’ll change that fuse too. Happy listening.
Did you get copper or silver versions for rails ?
When I asked Hifi Tuning owner Ahne if those rail fuses make a difference he replied: they are in signal path,aren’t they? -you need to change them!
I used the HiFi Tuning Supreme, whatever they are. To me, they sounded awesome!
Yeah, I’ve always wondered if the improved rail fuses on the BHK250 put the amp into the same class as the BHK300’s. I had waited for years for the BHK 250 to come out, and got serial #9 (very early production run!) just about the time the 300’s came out and Paul went all agog on how much better the 300’s were. But by that time it was too late and I had the BHK250. I’m just trying to see if anyone else gets a similar perceived improvement if they change their rail fuses, too.
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I have a smattering of Synergistic Research Blue’s in my LPS and DSD. I use Hifi Tuning Supreme everywhere else. In total there’s 19 fuses. The BHK300’s each need 6 of them. My old ears can’t really tell the difference between the SR and the Hifi Tuning. The bottom line is they sound good with them in place.