Fuses amperage question

Hello--I'm planning on swapping out the fuses in my Unison Research Unico SE integrated amp, and I noticed something peculiar. While the booklet says that the six internal fuses should be 1A, 500mA, and 10A (two of each), I look at the circuit board ratings next to the fuses and got a different story: they were, respectively, 1.3A, 1A, and 1.6A. If I go ahead with changing the fuses, should I go by the manual or the circuit-board indications? Thanks in advance for any advice,

JB Coleman
I don't know, but if I had to guess I'd chose to think the 10A fuses should have been listed as 1A. If for no other reason than 10A's is letting a lot of stuff pass, and the difference between 1A and 10A could be a simple printing edit error. In each other case the circuit board rating are higher than the recommended rating in the manual. Makes sense to me, but I'd get an OK from the manufacturer before I'd use 10A fuses, or I'd just use 1A fuses and see if it blew out pre-maturely. FWIW, probably not much. :-)
Check the actual fuses. They should be labeled as to what they are. Just take note if fast-blow or slow-blow. Get exactly whats in the amp now nothing else or damage may occur.
Greetings all

I recently purchased a McCormack DNA-1 Deluxe and it had blown fuse on one of the B+/Bi Power Supply Rails. I opened up the amp and saw the following fuses in the amp.


These are 10amp fuses correct?

I took a look @ the manual of the DNA-1 and it stated that for the B+/B- Power Supply Rail Fuses 8 Amp Fast Blo fuses should be used.

Is it ok to use 10 amp fuses if the manual calls for 8 amp fuses? What harm if any would I be doing to the amp should 10amp fuses are used?

Lastly I was only able to get 7 1/2 amp 250V Fast Blo fuses locally. I went everywhere I could. Is it ok if I use a lesser amperage fuse? Would I be cauing harm to the amp as well by use a lesser amperage fuse? Would SQ of the DNA-1 Deluxe be affected by different fuses with either lesser or more amperage than specified? So far I've been listening to the DNA-1 Dlx with only the 7.5 amp fuses installed and it sounds great. I'm just trying to make sure I don't mess up the amp or something worse.

Thanks so much and sorry for the novice questions.
You may want to ask why the fuse blew if you just bought it.Something fishy going on in there though it could be a simple matter of a cat crossing speaker wires????Dont know but you'd best,good luck,B
You BET. replace 'em with SAME VALUE or sometimes lower.
Not that it matters, but in an effort to protect my panels from my overzealous roomie, I replaced the 1.5 amp fuse with a 1 amp. And Told him to watch the loudness.

For USED equipment, I'd be careful. The higher value may have been installed to make the amp run for a while. If it popped right when fired up, you could have beefed. Now, you'll have a fight on your hands.
Replacing an 8 with a 10 is a NO NO. 'Proving' who changed the fuse...and the motive, will be impossible.
You may want to get the amp checked by a service pro.
Contact McCormack, and get the straight scoop: (e-mail: service@mccormackaudio.com) (phone: 703-573-9665)
Hi everyone.

I spoke to the seller about the DNA-1 Deluxe and he was very apologetic, sincere and professional. He told me that he had his tech bench test it and during the test a failure occurred due to a wiring gaff. Due to a very busy day the tech and the seller had a mis-communication and the seller thought the DNA-1 Deluxe was good to go. Again the seller apologized and also informed me of a 90 day warranty. I'll try to get further detail in writing. Now I didn't notice the 10 amp fuses until I was swapping them out.


I'm going to keep the 7.5 amps in there kind of like what you did with your Maggies. If I had an overzealous roomie I'd probably lock up my preamp so he couldn't muck with the volume. ;) I'm going to ask the seller about the 10 amp fuses and the situation that called for them to be put in the DNA-1 Deluxe. I won't hold my breath for an answer but in the mean time I'm going to keep listening to the DNA-1 Dlx make music and when my tech gets back from vacation I'll look him up and let him check out my amp.


Thanks for the contact info and I'm going to e-mail McCormack as well as SMcAudio and get the scoop.

So I'm guessing by upping the amp value on the fuses it causes the amp to receive more current and thus send out more power to speakers @ the cost of it's reliability? Sorry for the car analogy but is it kind of like bypassing the limiter on an engine allowing you to attain more power? I'm lucky the DNA-1 Deluxe is a tank & KEF Q-90 speakers are an easy load for it now. I'm listening to some Depeche Mode and Enjoying the Silence. ;)

Again a sincere thank you again to you folks for taking the time out to reply.
Talk to Steve McCormack, as suggested. He will give you an absolutely clear answer, and the best advice for your situation.

Good Evening all. Both Steve McCormack & Kris Jeter of SMc Audio got back to me with my inquiry about the 10 amp fuses that were in the DNA-1 Deluxe I purchased.

Here is what Steve said via e-mail & Kris echoed in a seperate phone conversation.

"The DNA-1 was originally delivered with 8A Fast-Blow rail fuses. These were changed to 10A fairly quickly because we were seeing some "nuisance" blowing of the 8A fuses on turn-on. The 10A Fast-Blow has remained the standard DNA-1 rail fuse since then. You won't hurt anything by using a lower value so long as they are FAST Blow."

Well I'm relieved. Thank You again everyone for chiming in and Thanks to Steve McCormack and Kris Jeter.

Now onto the researching of "audiophile" fuses. ;) Don't worry I won't post anything on this thread I'll read the older ones on the forum

All the best.

Now onto the researching of "audiophile" fuses.
Jedinite24 (Answers | This Thread)
FWIW, Steve McCormack installs Furutech fuses in his VRE-1 preamp.