[beat]

Hey all,
Does it matter if your fuses are rated at 250v vs 120v? or is it just amps that matter. Since this fuse popped after flipping the switch from 230 to 115 do I need to replace the fuses with 120s? What is in there are 250v 5a. FYI, I have not heard a note of music out of these yet. Did they work right before I flipped the switch? I dont know? They are brand new.

[electricbear]

I've never come across a situation where the voltage rating on a fuse has made any difference, I've always been more concerned about the current rating. Where you may have run into problems is that in switching your amp from 230 to 110 it may cause it to draw more current, possably twice as much. I'd put a call into the amps manufacturer to check if this is the case. You may need to put in a fuse with a higher current rating.

[bubba966]

I don't know if you could do a swap w/a 125v fuse. But if you can, you need a 125v 10A fuse.

[StevenACNJ]

I have been using Bussman fuses from Home Depot (250V -5A) for my amps. Apply some Walker SST and your in business.

[doug s.]

Hey all,
Does it matter if your fuses are rated at 250v vs 120v? or is it just amps that matter. Since this fuse popped after flipping the switch from 230 to 115 do I need to replace the fuses with 120s? What is in there are 250v 5a. FYI, I have not heard a note of music out of these yet. Did they work right before I flipped the switch? I dont know? They are brand new.

what do you mean, that you flipped the switch from 230 to 115?  first of all, running 230v into a 115v rated component could fry it.  (running 115v into a 230v component would likely do nothing, as there wouldn't be enuff juice to get it running).  now, if you had a piece of equipment set up for 230v that has a switch to allow it to run 115v, & it came w/a 250v/5a rated fuse for the 230v setting, if ya run it at 115v, you will need to up the fuse to 10a.  the reverse is also true - if yure running gear at 115v w/a 5a fuse, and the gear can be switched to 230v, then you should *reduce* the fuse's amperage rating to 2.5a...

hth,

doug s.

[YoungDave]

Here is the deal with fuses:

First, There is no difference in the "sound" of one fuse or another.  Power connections, fuse connections, etc., do matter, though.  But the fuse, unless blown, is just a very short piece of wire.

Now then, as to fuse ratings, a 230V fuse is built so that it will blow with a gap large enough to shut down current driven by 230 VAC.  A 115V fuse might not blow a wide enough gap to ensure a shutdown.  You may certainly use a 230V fuse on a 115V circuit, but you must not use a 115V fuse on a 230V circuit.

The other two specs on fuses are blow time and current rating.  Some items use a lot more current than the rated current for a short period of time, and they get "slow-blow" fuses.

As to current rating, you must never use a fuse rating greater than the manufacturer's specs - if the right size fuse blows, your unit is probably broken.  For exampe, if a device is rated for 7 amps, you must never use a 10 amp fuse - it might not blow in the event of trouble.  You should not use a fuse smaller than 7 amps, as it might blow when there is no problem.

Also, that previous poster had a good point - what's with switching from 230 to 115?  You don't have 230V to run it on unless you are overseas.  If you are overseas, you do not have 115V to run it on, unless you are using a separate step-down transformer.  So how did you come to switch this thing?  That might cause bad damage.

[beat]

Thanks guys,
Doug, I was trying to run it with power straight from the wall..115. I dont have the step up transformers yet to allow me to run it at the 230 it was set for. I found the internal switch and moved it to 115 with the 5a 250v fuse it came with in there still. The front led was only on for like 5 seconds before it popped the fuse. The tubes never even glowed.

It seems the consensus says I run a 10a fuse if I continue to run it at 115, eh?

I guess my other option is to wait till my step up trannys get here and switch them back to 230.

[YoungDave]

Yep, 10A should do it for 115.  

I don't know of any reason to get an external step-up to run it at 230 - the 230 switch just rewires the internal transformer to step the voltage back down to the voltage actually used in the power supply - typically 75-80 VDC after rectification is a SS unit, much higher in a tube unit.  At any rate, the internals do all the same work, regardless of 230-115.

You would be going to great lengths to step up the wall voltage, and then step it right back down inside the unit.  Save your money for things that will improve the sound!

[doug s.]

Thanks guys,
Doug, I was trying to run it with power straight from the wall..115. I dont have the step up transformers yet to allow me to run it at the 230 it was set for. I found the internal switch and moved it to 115 with the 5a 250v fuse it came with in there still. The front led was only on for like 5 seconds before it popped the fuse. The tubes never even glowed.

It seems the consensus says I run a 10a fuse if I continue to run it at 115, eh?

I guess my other option is to wait till my step up trannys get here and switch them back to 230.

basically if the woltage is halved, then the amperage is doubled.  which is why it likely blew a 5a fuse when ya tried running it on 115v.  

doug s.

[doug s.]

Yep, 10A should do it for 115.  

I don't know of any reason to get an external step-up to run it at 230 - the 230 switch just rewires the internal transformer to step the voltage back down to the voltage actually used in the power supply - typically 75-80 VDC after rectification is a SS unit, much higher in a tube unit.  At any rate, the internals do all the same work, regardless of 230-115.

You would be going to great lengths to step up the wall voltage, and then step it right back down inside the unit.  Save your money for things that will improve the sound!

any isolation transformer will likely improve the sound of audio gear, assuming it's sized properly.  and, it's also possible that an amp, if originally designed to run on 220v, but w/a woltage switch for other markets, will actually sound better on 220v than on 115v.

ymmv,

doug s.

[guest1632]

Hey all,
Does it matter if your fuses are rated at 250v vs 120v? or is it just amps that matter. Since this fuse popped after flipping the switch from 230 to 115 do I need to replace the fuses with 120s? What is in there are 250v 5a. FYI, I have not heard a note of music out of these yet. Did they work right before I flipped the switch? I dont know? They are brand new.

[Lost81]

While we are at this, how about thermal breakers versus fuses?

Jon Risch is of the opinion that thermal breakers present less resistance during normal operation.

Also, I believe there was a recent thread on Asylum about how ceramic tubed fuses (as opposed to a glass tube) supposedly sound better... hmm...


-Lost81

[guest1632]

While we are at this, how about thermal breakers versus fuses?

Jon Risch is of the opinion that thermal breakers present less resistance during normal operation.

Also, I believe there was a recent thread on Asylum about how ceramic tubed fuses (as opposed to a glass tube) supposedly sound better... hmm...


-Lost81

[andyr]

While we are at this, how about thermal breakers versus fuses?

Jon Risch is of the opinion that thermal breakers present less resistance during normal operation.

Also, I believe there was a recent thread on Asylum about how ceramic tubed fuses (as opposed to a glass tube) supposedly sound better... hmm...


-Lost81

Hi, Lost,

Ceramic fuses seem to be getting more widely used for hi-fi gear.  I think it would take better ears than I have, to identify a difference in sound coming from my speakers when I substitute a "ceramic" for a "glass" one one but I use them everywhere because they introduce less noise ... possible because the ceramic filling inside the glass shell stops the fuse wire from vibrating with current, like it does inside an ordinary glass-tubed fuse.

How do I know this ... the men in blue here in Oz use ceramic fuses in their radar guns; ordinary glass fuses generate too much noise which makes the radar speed readings inconsistent!!

Regards,

Andy

[guest1632]

Hi, Lost,

Ceramic fuses seem to be getting more widely used for hi-fi gear.  I think it would take better ears than I have, to identify a difference in sound coming from my speakers when I substitute a "ceramic" for a "glass" one one but I use them everywhere because they introduce less noise ... possible because the ceramic filling inside the glass shell stops the fuse wire from vibrating with current, like it does inside an ordinary glass-tubed fuse.

How do I know this ... the men in blue here in Oz ...

[andyr]

now why do manufacturers use the shorter 5mm fuses versus the more standard longer fuses? I've seen them in speakers as well as preamps....

Don't know ... but you can get "ceramic" fuses (as well as "glass") in the 5mm size as well.

Regards,

Andy

[guest1632]

now why do manufacturers use the shorter 5mm fuses versus the more standard longer fuses? I've seen them in speakers as well as preamps....

Don't know ... but you can get "ceramic" fuses (as well as "glass") in the 5mm size as well.

Regards,

Andy

[ginger]

The designation of the longer fuses is 3AG
Its an "imperial" units size (inch length by 1/4 inch diam).

The other type is usually called M205 meaning METRIC 5mm diam and 20mm long so you Yanks probably wouldn't understand about them.

They work the same its just an IMPERIAL vs METRIC thing.

Cheers,
Ginger

[guest1632]

The designation of the longer fuses is 3AG
Its an "imperial" units size (inch and a quarter length by 1/4 inch diam I seem to recall).

The other type is usually called M205 meaning METRIC 5mm diam and 20mm long so you Yanks probably wouldn't understand about them.

They work the same its just an IMPERIAL vs METRIC thing.

Cheers,
Ginger

[ginger]

Just ahad a quick browse of the catalog.

3AG and M205 (plus some weirdos like size "00" etc) are all available in both ceramic and glass.

Also all available in:
Ultra Rapid
Quick Blow
Anti-Surge - has "spring" element in it or a plated wire

I generally use quick blow on DC rails of my amplifiers and anti-surge on the mains wiring because I use toroidal power transformers which have large magnetising current surge at switch on.

Always fuse both Active and Neutral of the mains wires so that when you come across that one power outlet which the electrician wired backward you still have full protection.

Probably more than you ever wanted to know about fuses.

Cheers,
Ginger