Amazing speaker fuses

[2chGearBuff 428]

Okay, so I get a call at work today from my son.  He is home because he decided to virtual school (high school) for this semester until this Covid crap is under better control.  Anyhow, he tells me he was listening to my main setup in the basement and he walked away for 30 seconds and when he came back, the left channel didn't have any sound.  He assures me he wasn't playing it loud (not that it matters - have Sunfire 300x2 driving my Amazings), so loud hasn't been a problem.  He also tells me the Radio Shack APM-500 is showing output is going to the left channel (meters are moving).  I tell him I can't talk him through what to check over the phone at the moment and that we will deal with it when I get home.  So, after dinner, we go about the typical steps to start with the basics in troubleshooting.  Figure it was a good time to teach him how to figure stuff out on his own in the future!  We try a different source, still no sound.  Try switching off the External processor switch on the C16 (feeding signal through equalizer), still no sound (had an issue with a dirty switch there this summer - so had to make sure that wasn't it).  Then switched right and left inputs on the amplifier to make sure it wasn't an output problem with the preamp, and also switched from Main 1 out to Main 2 out.  Silence still on the left.  Then switched speaker wires, left to right and right to left.  Still no sound out of the speaker to the left (now the amplifier's right speaker terminals).  So, figure it is a speaker issue.  Pull my speaker wires and put my multimeter on the speaker terminals - OL - open circuit.  So, pull the fuse and sure enough, clear space between the two ends.  

 

Now the fun begins.  I get looking at the fuse, and I don't ever remember seeing a fuse with a center element like this.  So try and read it, with my eyes as sucky as they are, even with my glasses, makout Buss MD??4  250V (on other end cap).  So my son reads it and comes up with MDO4.  I'm like, I don't think that is correct.  Should be MDL, maybe.  Anyhow, we get searching and the MDL 4 is a slow blow fuse.  I've always thought speakers were usually fast blow fuses, similar to amps, etc.   So, I tell him "go pull the other fuse out of the right speaker".  He comes up with the weird ass looking fuse that I've never seen the likes of before!  But then I get looking on here and I see where someone posted about blowing fuses on the Amazing Silvers and how there was a service bulleting about changing the fuse rating to MDL 3.2A because the 4 wasn't proper to protect them.  Then he mentions in the post about MDQ fuses, and wham, Google search, there is the funky fuse from the right speaker.  So, apparently my Amazings had MDQ4 fuses.  Who knew?  Not me, that's for sure.  

 

So, being that MDL and MDQ fuses are similar in nature, i.e. slow blow or time delay whichever you prefer, the only difference I have found in my searching is that the MDL may go a little bit quicker than the MDQ.  Will it matter?  There is also a pretty substantial $$ differential between the two, to the tune of about $3.40 more for the MDQ (from local sources).  Question is, will it be worth the difference if they are nearly the same fuse as far as performance goes?  And if so, what "is" the advantage?

 

Neil

Edited October 30, 2020 by 2chGearBuff
Added additional text

[weitrhino 1,443]

I don't have a direct answer for your question of "what is the advantage" of the MDQ-type fuse but I can say I never blew any fuses in my Amazing Hybrids until I had a PT-2400 for a short time, and even then it only happened because I was pushing the boundaries to see how much power the Hybrids could take. That's when I began looking for replacement MDQ-4A fuses and found them to be rather expensive. Not wanting to cough up the price or have to hunt them down every time I needed one I decided to install circuit breakers instead.

 

Somewhere on this site there's a write-up I did 9 years ago but I couldn't locate it via search. I used a breaker that has the same physical profile of the fuse holder in the Amazings. Yes, a breaker is slower than a fuse but I'm not the volume freak I once was so I just don't worry about that. I expect the breakers to pop if there should ever be a problem in the system.

 

 

[RodH 4,866]

MD* series fuses are slower than fast blow types.

ACG3 or ACG4 is a better choice IMHO. Fast reaction.