In regard to the BHK300 amp question, PS Audio’s response is:
The rail fuses would be the ones to experiment with different styles. They protect the internal boards and are not affected by the incoming power issues. Adding a SDFB to the incoming power would only be protecting the 10A incoming fuse.
Sounds like a (official) plan!
Cheers.
I honestly think you would hear a decided improvement with the SDFB and a Sluggo in the external fuse holder.
More days on the silver slug in the P15 and a High Purity Copper Sluggo in the Decware SEWE300B amp. . . and man oh man. . .it’s a significant improvement with the seasoning and settling in.
I think each is the right fight for the component, and there’s a very natural tonal balance with a deeper soundstage, smoothly meaty instrumental images, and dynamics both macro and micro that bring a realistic feel to the presentation.
In a few days I’ll have a third SDFB to use with my DSD Mk II–which has easy access to the fuse on the back panel. (All my SDFBs have and will have identical power cables running to and from them). Two pairs of ears I trust have told me that they felt the third one was as significant an improvement to the first. . . that’s exciting if it proves true.
Curious to know how SDFB will sound in MK2 because of its low current requirement.This is where I have the M-2 fuse going and it is quite an improvement over M-1.
These two persons noted that they used their third for DAC or Streamer so I suspect an improvement. And I think the MK II uses a bit more current than some DACs. Anyway, the Mk II certainly responds well and with differentiation to different fuses. I’ll certainly report impressions.
It would be insane to put slogo’s in the rail fuses. There is no way to detect changes in current demand for them. You would be asking for serious damage should something go on in the amp.
Interesting…help me understand the risk if you don’t mind…
Are these fuses “downstream” of a power supply or current reservoir in the BHKs that are not otherwise subject to current regulation by the “primary” fuse?
Thanks in advance/regards.
The fuses for the rails are independent of the one in line for the transformer. They are there to prevent DC offset from reaching the speakers. Mosfets unlike Bi-polar junction transistors usually fail open not short but other failure mode conditions could cause excess current to occur in use. 10 amps draw after the power supply does not have any direct relations with 10 amps draw before the power transformer. If that logic of the line fuse doing the protection than they would not have designed and rail fuses into the circuit. The power supply has high storage capacity. Think of the line fuse on a P 15 being 5 amp and the breaker protecting the outlets being 10 amp.
Sounds like an issue…
To be clear, the MOSFETS and/or transformers in the BHK amplifies we are discussing can “store” and/or pass along current that exceeds a safe level through the “rail fuses” and cannot be regulated or prevented by the SDFB “controlling” the mains feed into the amplifiers? Am I reflecting back correctly?
[I am not trolling you and this is helpful to me and, hopefully, other interested parties.]
Thanks again.
[@Philip_Gan - please note most recent discussion.]
Scotte1,
Yes that is exactly my concern. In order for someone to use the SDFB in that portion of the circuit it would have to be in line at that point in the circuit. There would be no way to do that and the power at that point is DC not AC. You are welcome.
Thanks @scotte1 !! I’ll have to get back to PS audio!
Thanks @lonson - I presume you refer to replacing the 5A (for 230V countries) fuse with a 5A SDFB?
The mosfets don’t store power. The capacitors in the power supply do.
I assume that is correct–I was thinking replacing the fuse in the fuse holder on the back of the component. To verify I would suggest contacting the friendly and knowledgable head of the outfit Mark at
verafiaudio@gmail.com
There’s confusion within this topic about what the H means after the amperage. It denotes ‘breaking capacity’ and an H fuse is typically ceramic whereas if it’s not H it’s likely to be glass. Glass fuses can shatter when they blow, ceramic fuses ought not to. I suggest people that have never done so read up about the meaning of each letter and number on fuses for themselves. An H breaking fuse can be slow or fast blowing.
I had a strange email reply from PS Audio, essentially saying “We would not recommend using sluggos in any application.”. That was with my email trail specifically referencing the SDFB and sluggos. My sense is that he was not familiar with the SDFB.
I think I will get my advice from this forum (thanks @sixpack1 )!
I have seen a post or two from Paul M. that were not “supportive”. That said, I would not expect him to endorse such a practice given the potential headaches of dealing with a mishap involving one of PSA’s products.
I think informed diligence is a necessity here. If I were you, I would have another conversation with Mark or “Underwood Wally” and be very specific about the amplifier topology you are considering with the SDFB.
Assuming @sixpack1 (John) is correct (and I have no reason to doubt him), I don’t think it makes sense to use Sluggos in lieu of the internal, “rail” fuses.
That does not necessarily mean the BHK would not benefit from a SDFB/Sluggo for the “mains supply”. I believe you can return your purchase if this proves ineffectual.
My $0.02.
SEE
Users need to realize the only purpose of the sluggo is to connect the two sides of the fuse holder to complete the circuit. They do not have any connection to the box which takes over the function of protection. In order for SFBD to be functional it must be in series with the item you are protecting and the source of the AC power. If one were to want to protect a BHK 250 it would require two SFBD set ups one for the main power and one for the tube power with of course the appropriate current rating and reaction time fast or slow. It would also require a second iec inlet to be installed with addition power cords.
Exactly.
