Fuses for the BHK Preamp


#1

I know from looking at the fuse and the back of the preamp that the fuse is a 2 amp 5 x 20 mm, but it is not clear if it is a fast blow or a slow blow fuse. I suspect that it is a slow blow fuse, but the manual is silent on the type of fuse and I couldn’t find an answer in other threads (although I did see one confirming it is a 2 amp 5 x 20 mm fuse).

So, is it a slow blow or a fast blow fuse? Thanks in advance.


#2

Greetings,

They are designated as “T” fuses thus slow blow. I installed a Synergistic Red in mine.


#3
odysseas said Greetings,

They are designated as “T” fuses thus slow blow. I installed a Synergistic Red in mine.


Did the Red fuse made an audible improvement?

#4

Interestingly it did. I had experience from the older SR-20 fuses installed in my dac (W4S Dac2) and amp and tried to see what they’d do on the preamp. I had enough hours on the BHK pre with the stock fuses and tubes to get a good perspective of sound. The Red fuse opened up the soundstage quite a bit and the vocals seemed more focused, more centrally placed and very open. To be quite honest although the immediate effect was that of more focus and “resolving power” if I can describe it, I thought that the sound turned a little too much to the lean side of optimum. About a couple of weeks later (with the SR Red having about 5 hrs per day use) the Tungsram tubes came in and things improved with a great 3d soundstage, ever so slightly warm vocals while keeping the “openness” of the SR Red.


#5

My BHK preamp would not turn on tonight, so after checking that it’s plugged in etc. I will go fuse shopping tomorrow. The OP of this thread found a 2 amp fuse in his unit, but the photo of the back panel in the manual shows 1.6AH. Was the fuse upgraded from the original spec? Is it safe to use a 2A in place of a 1.6? Does the ‘H’ indicate one of those high-current fuses like in the BHK amps? (I’d like to have the right fuse on hand before I unpack the preamp from the rack – not a trivial task in my setup.)

Fuse information should always be in the manual!


#6

Yes, fuse information should always be in the manual [as it is in the amp manual].


#7

@magister, did you discover what is inside your BHK? I was looking over at CableCo.; where did you plan to go fuse shopping?


#8

On the basis of what Murrayb wrote, I went to Radio Shack and came home with 2 amp slow-blow fuses. I pulled the system apart and found a white-bodied (ceramic, I think) fuse with gold-plated ends. It is labelled T2AH 250V. T = slow blow, H I am guessing is for high current.

Amazon does sell the ceramic ones. You can get a pack of five high-current ones here for $6 plus $5 shipping. I may order a pack just to have on hand. Maybe someone can explain the advantage of the ceramic construction. It’s a pain since you can’t tell by looking if it’s blown!

I’m back in business now :slight_smile: . But I’m now thinking about trying a high-end fuse; I was planning to do that at some point, and the one from the Shack is probably not as good as the original. People here have reported good results with Synergistic Research. I will probably call the Cable Company; they seem to have a better selection than some other places. Suggestions welcome!


#9

Yes, I filled a shopping cart at CableCo with the SR Reds; their selection is excellent. For the 1.6/2.0 for the preamp, and 2 each of the 2A and 10A for the amps as recommended, it’s a $450 shopping cart. With the discounts available on the now-discontinued HiFi Tuning Silver Star, one can double that cart quantity for backups for about $165. I don’t tend to be “penny-wise-pound-foolish” on my audio gear, but that’s a pretty significant difference. And with an order about to go in for MG Audio ICs & possibly speaker wire, as well as an upgrade on the DSP for my Aeris, well…

Another of our colleagues here said he had ordered the HiFi Tuning Silver Star versions, but he did not report back his experience.


#10

Palerider, I’ll be very interested to find out how the Red fuses work for you. I was thinking of a different strategy (the bank account is a little thin after ordering both the BHK pre and the DMP this fall). After reading some posts here and on Audiogon, I may get a SR Black for my preamp (under the theory that I want the best signal possible coming out of the pre, since the amp can’t improve upon what comes into it) and then do the amp later if I find that the fuse in the pre makes a difference.


#11

CHANGE OF DIRECTION: Having wound my way through the fuse threads in other topics, I think I am going to try the AM Beeswax. I almost did this a while back, and now it seems like the thing to try.


#12

I bought three SR Black fuses (they had – maybe still have – a special where you can get three for the price of two, and they don’t have to all be the same value). Five days ago I installed one in the BHK pre. I had never played with high-end fuses before, and I still don’t get why a little bit of wire makes such a difference – BUT IT DOES. Wider soundstage, better separation of instruments, improved tone color, better ability to hear inner details; the whole presentation, which was pretty darn good to begin with, is kicked up a couple of notches. Of course, YMMV. But I would say that anyone who can afford the BHK or similar stuff should experiment with a fuse for $100. Get them from a place where you can return them if you don’t hear an improvement. Still don’t know why they matter but the aural evidence is indisputable. As others have noted, the SR Blacks do require break-in time (I’d say 25 hrs minimum with continued improvement up to about 100 hours) and experimentation to find out which direction sounds better.

Today I will put the other two I bought into the BHK 250 and we’ll see what happens.


#13
magister said I still don't get why a little bit of wire makes such a difference -- BUT IT DOES.
Which is all that matters. But the why continues to bug me.

Please report back when you put the other two in.


#14
magister said I bought three SR Black fuses (they had -- maybe still have -- a special where you can get three for the price of two, and they don't have to all be the same value). Five days ago I installed one in the BHK pre. I had never played with high-end fuses before, and I still don't get why a little bit of wire makes such a difference -- BUT IT DOES. Wider soundstage, better separation of instruments, improved tone color, better ability to hear inner details; the whole presentation, which was pretty darn good to begin with, is kicked up a couple of notches. Of course, YMMV. But I would say that anyone who can afford the BHK or similar stuff should experiment with a fuse for $100. Get them from a place where you can return them if you don't hear an improvement. Still don't know why they matter but the aural evidence is indisputable. As others have noted, the SR Blacks do require break-in time (I'd say 25 hrs minimum with continued improvement up to about 100 hours) and experimentation to find out which direction sounds better.

Today I will put the other two I bought into the BHK 250 and we’ll see what happens.


Where did you see the 3 for 2 special?

#15

I got mine from The Cable Company, but I think the promotion is from Synergistic Research so other retailers are probably offering it.


#16

Ok thanks.

Do the DS and DMP use the 2amp slo-blow 5x120 as well? IIRC the DS does but don’t own the DMP, yet. That could be a perfect reason to have 3!


#17

@magister , so the 100h break-in period is over, any positive results? wink


#18

Yes, definitely positive. The effects are similar to what I observed when putting the Black fuse in the BHK preamp. The soundstage is larger, there is better separation between instruments and voices, and tone colors are improved.

In one of his posts, Paul suggested that people who wanted to experiment with fuses in the BHK amps should start with the two power supply fuses, so that’s what I did. I don’t know how much additional benefit, if any, would result from changing the four voltage rail fuses. That would get a little pricey of course. Has anyone done this?


#19

magister,

I just did it. I started with the 2 main fuses as Paul suggested. Took advantage of the sale from the cable co, replaced 2 rail fuses last week and the last 2 today. I think it’s too early to judge the sound but I noticed the rail fuses sound pretty good as soon as I inserted them vs. the main fuses sounded horrible right away before break in.

Allan


#20

Allan,

Thank you for this. I assume you used the Black fuses. I found that they didn’t need as much break-in in the BHK 250 as the one in the BHK preamp did (no idea why). I started with the writing going into the amp, listened for a couple of hours, then reversed them. I got better detail with the writing going out, so that’s how I left them. Out of curiosity, did that match your experience?

Please let us know your feelings about SQ after the four rail fuses settle in.