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why do hi-end fuses keep blowing, while std don't?

I've had my McIntosh MC275 for several years running flawlesly. Up until last Nov I was using stock KT88 and rolled small tubes and had a Hi-Fi Tunning fuse without issues.

In Nov-13 I upgraded the KT-88 to Psvane black bottles measuring 60mA plate current. A few power-ons after I rolled the tubes, I turned on the amp to let it warm up, but returned to a blown fuse. I thought a tube might be bad so used a std fuse, but never had a problem again.

Two months ago I bought a new high-end fuse, replaced it, and soon thereafter the same happened: blown fuse. I replaced it with a std fuse again, which is still running.

So I want to upgrade the fuse, but chances are if I use the 2A fuse it will happen again. Yet I don't want to use a higher value fuse. I'm thinking the Psvanes might be drawing significantly more current than the stock KT88 and the Hi-Fi Tunning fuse might have a tighter spec, driving said fuses to fail while the std ones survive. Would you agree?

Suggestions as to how to resolve this?

thanks much!
lewinskih01

Showing 5 responses by summercrema

summercrema
5 posts
 
Hi Lewinskih01, have you found the reason causing the upgraded fuses to blow , I am in the same situation, I purchased Furutech  Pure Transmission and HiFi Tuning fuses ( same spec on both Slow blow 5x20mm 3.15A) unfortunately both did not last more than 4 days, good music improvement  while they were working though (soundstage, extension of tones , high and low  ) clean and clearer imaging. Tested with following singers CDs, Madaonna The immaculate collection, Dire Strait , Karen Souza Essentials, Kandace Springs Soul Eyes . Iam prepare to buy the fuses again as long as I can find the solution to the problem. 

I agree with what Hevac1 saying,  I have asked a friend to measure the loading on stock fuse and the upgrade fuses as a start ... 

If you guys already find a solution I like to hear about it , many thanks .

  

summercrema
5 posts
 
Hi Fi Tuning fuse purchased from Analogue Seduction in UK ,  the stock fuse in my  integrated  Amp Cayin CS88a is by LittelFuse 3.15A 250VP , I think  it is a 213 series from catalogue , Littelfuse make many version of the 5x20mm 3.15A fuses. The Amp shipped with two extra fuses  and there is a Littelfuse reseller not far (30km) from me I can go there to find series is the I got.  I thought same rating and same dimension of the fuse is good enough apparently not the case. 
summercrema
5 posts
 
Just an update on the fuse problem I had with the amp,  paid another $120 on a isolation transformer with build in InRush soft start circuit  to use it with the Tube Amp,  no more blown fuse for 7 days already, two blown fuses already cost more than $120. the gain in sonic difference well worth it. 
summercrema
5 posts
 
I bought it from them Tortech,  https://www.tortech.com.au/product-category/isolation/

it is available on ebay.com.au
 ISO600VA.

My tube amp is only 6 months old, manufacturer will no commend on third party hifi fuses and fuse manufacturers will say anything either.
After googling few hours Isolation Transformer  came up few times and found out Tortech has a soft start circuit to to limit inrush current problem.

Actually I turn on the ISO600 before I turn on Tube Amp.  
summercrema
5 posts
 
correction I mean to type $160 not $120.
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