Synergistic Red Fuse ...

OK, Meanwhile I found folowing answer which seems to be logical and could be usefull if there is no mention in manual. Anyway, if there is something wrong or to be added, please do, I would like to clarify this aspect and order some fuses next week. 

" The answer to this depends on the application. The main purpose of a fuse, in any application, is to prevent a fire. If the fuse is in the loudspeaker circuit, ie, in series with the loudspeaker as a load, then it needs to tolerate occasional overloads, but open on continued overload - so, medium slow blow. If the fuse is in series with a transistorised power supply's pass transistor, then it needs to be a very fast blow. If the fuse is in the mains input lead before any power supply unit, then it needs to sustain the start-up current required to charge the main filter capacitors - so, slow blow. In summary, look at the application."

Fuse in Linn Numerik DAC it is located next to power in socket, so I assume that it is before any transformer power supply, so it should be slow blow?

Thanks

Mlaurentiu, I looked at the manual for the Linn Numerik DAC, and at the section of this Wikipedia writeup which among other things addresses BS (British Standard) 1362 fuses.

It appears that the 5 amp fuse referred to in the manual is in the mains plug, not in the DAC itself. The DAC itself apparently has a fuse with a MUCH smaller current rating. That rating is not indicated in the manual but may be indicated on the rear of the unit, and/or on the fuse itself. Also, note the following statements in the Wikipedia writeup:

There are two common misconceptions about the purpose of the fuse in a BS 1363 plug, one is that it protects the appliance connected to the plug, and the other is that it protects against overloading. In fact the fuse is there to protect the flexible cord between the plug and the appliance under fault conditions....

... BS 1362 specifies sand-filled ceramic-bodied cylindrical fuses, 1" (25.4 mm) in length, with two metallic end caps of 1/4" (6.3 mm) diameter and roughly 1/5" long.

I’ve seen separate indications confirming that the 25.4 mm length dimension is the overall length of the fuse including the end caps, and so I’m not sure that the 6.3 x 32 mm fuses provided by SR and other makers would fit in the plug.

Also, I found this set of time/current curves for the BS 1362 fuses, which can be used to determine whether those fuses fall into what is generally considered to be the fast blow or slow blow categories, or into something in between. Post back if you’d like me to make that determination.

Regards,
-- Al

Hi, thanks for your feedback, so I just reach home and I check it exactly, I should do this from the begining: I found out that the fuse have size of 5x20 mm and the size of the wire inside fuse it is very thin (I suppose arround 0,2mm), so seems to be fast burn fuse. On the other side, I found out that T from description of fuse comes from slow burn fuse. It is wright?

Also, one the fuse and backside of DAC it is written that fuse it is type T800 mA and consumption it is aprox. 20VA.

A T800 fuse is slow blow.  The thinness of the wire reflects the small 800 ma (0.8 amp) current rating of the fuse.

Also, given the reports that have been made in this thread by several people indicating that in some applications SR fuses have had to be derated somewhat to prevent them from blowing when they shouldn't (i.e., to have current ratings that are a bit higher than specified by the equipment manufacturer), it would seem prudent to choose an SR fuse rated at 1 amp, rather than 800 ma.  Both ratings provide a wide margin relative to the 20 volt-amp consumption of the DAC, but the brief current surge that may occur at turn-on could be significantly larger.

Regards,
-- Al
 

OK, so for DAC I will choose 1A instead of 800mA, what about amplifier where existing fuse it is 4A slow blow? Next value from SR it is about 5A. Do you recommend also greater value of 5A?