Fusing Revisited

[jwjensen356]

By Googling the fusing subject and Dynaco I found something I don't think has been mentioned yet. This was some commentary found in the manual for the Dynaco Mark VI (tube) amplifier. The Mark VI is provided with a speaker fuse. It is 5A in rating and the fuse will not fail if the amplifier is operated at full power (120W into 8Ω). Dynaco then says "Therefore, it provides NO PROTECTION for your speaker."

Dynaco then goes on to discuss speaker fusing:

"The chart below shows the highest sustained power level that will not blow the fuses shown.

"Experience suggests that on this basic power levels of 10 watts are safe starting points for most high fidelity speakers using a single woofer."

3AG 4Ω 8Ω 16Ω

--- -- -- ---

0.5W 1W 2W 4W

0.75 2.2 4.5 9

1.0* 4 8 16

1.5** 9 18 36

* Dynaco A-10, A-25, A-35

** Dynaco A-25XL, A-40XL, A-50

John

[jwjensen356]

Sorry that the formatting of the table is messed up. But, in my case for the A-50, it is 18W for a 1.5A rated 3AG fuse with the speaker operating off the 8Ω tap.

John

[dynaco_dan]

Hi John;

The Other forum topic, "fast blow fuses", has everything I could find on Dynaco fast blow fuses and fusing methods, but is readily adaptable to other speaker brands.

There is also a referral to Crown's website for some valuable insight.

Here in the AR and Advent library is fusing information using slow blow fuses, well worth while reading as well, as a reference.

You chose a good topic descriptive name.

[jwjensen356]

Looks like I plowed over old ground, you had it well covered, including the same table. I've got them installed with fast-blow fuses so I feel secure now.

Now to listen to the music.

John

[dynaco_dan]

Hi John;

I was very brief in pointing out the, "Other" forum, so as not to repeat myself too much.

I also wanted to add just a tidbit about slow blow fuses and Crown.

I am certain that there will be more fusing information come up now and again, always room for improvement.