Your opinion on Fuse speaker location

famousg

famousg

New Around These Parts
Joined
Jul 31, 2023
Messages
3
All Phase users fit a support fuse on the loudspeaker input.
I think that it's fragile and not very styled...

I hope to inclued the support fuse directly onto the chassis just next to the speaker outputs...

Please let me know your opinion about it....
 
We don't use speaker fuses.
Don "Watts Abundant" who is a member here, long ago developed a speaker protection relay board for the 400 and 700 watt amps.
Known here as a DC Protection Relay Board, or DCP board.
Here's the link.
http://www.wattsabundant.com/
 
famousg said:
All Phase users fit a support fuse on the loudspeaker input.
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Not even close. Most of us here understand physics and Ohms Law. A proper fuse (one that will not open when it gets loud) will not interrupt quickly enough to prevent catastrophic damage to "most" speakers. There are exceptions such as JBL or Altec Professional Sound Reinforcement and others that employ built-in protection.
As George S. said, get the DC Protection Relay/Delay from Don before you connect any speakers you really care about to an unrestored Phase Linear amplifier.
 
Years ago before DCP relays I fused my speakers with my 400. Kept me from blowing speakers when I got drunk or stupid
 
Skratch said:
Years ago before DCP relays I fused my speakers with my 400. Kept me from blowing speakers when I got drunk or stupid
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I did as well. No more. Thanks Don!
 
laatsch55 said:
Oh yeah .....those 2,000.00 dollar fuses..
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A $2000 fuse makes these capacitors an absolute bargain. On sale for $2399 regularly $3999.

Recently I happened to speak with the order desk about a more modest item and I asked if any customers actually bought mega bucks capacitors. Answer was "Yes, not many but they do sell".

Duelund capacitor.PNG
 
62vauxhall said:
A $2000 fuse makes these capacitors an absolute bargain. On sale for $2399 regularly $3999.

Recently I happened to speak with the order desk about a more modest item and I asked if any customers actually bought mega bucks capacitors. Answer was "Yes, not many but they do sell".

View attachment 76864
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Doggone, it is out of stock...
 
Before WO audio, before Watts Abundant, there were in-line fuses. I was quite fortunate to have these in place on several occasions when the amp went bye bye with a fried output or two. So if you don't have Watts Abundant DCP protection boards I would highly recommend using the in line fuses with your PL amplifier. Several speakers came with em as well and they didn't sound bad at all with these fuses in place, i.e. CV D9's.
 
I = square root of P/4R is the formula that was on the old Phase Linear site that I think was maintained by Ed. P is speaker power handling in watts if I remember correctly.
 
Gibsonian said:
I = square root of P/4R is the formula that was on the old Phase Linear site that I think was maintained by Ed. P is speaker power handling in watts if I remember correctly.
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Gib, my understanding is that a fried output will open the corresponding Rail Fuse, and possibly invoke the protection circuit. Did you ever actually blow and replace the speaker fuses?

You are correct, this formula is found on Page 5 of the updated Phase Linear 700 700B Service Manual dated 2/81.

So if your 8 Ohm speakers are rated for 200 Watts, that is equal to 6.25. And the square root of 6.25 is 2.5, so 2.5 Amp Fast Blow Fuse.
For Lee, because his speakers are rated for 1,250 Watts, he will need an 8.8 Amp Fuse, closest actual Fuse is 10 Amps!
 
mlucitt said:
Gib, my understanding is that a fried output will open the corresponding Rail Fuse, and possibly invoke the protection circuit. Did you ever actually blow and replace the speaker fuses?

You are correct, this formula is found on Page 5 of the updated Phase Linear 700 700B Service Manual dated 2/81.

So if your 8 Ohm speakers are rated for 200 Watts, that is equal to 6.25. And the square root of 6.25 is 2.5, so 2.5 Amp Fast Blow Fuse.
For Lee, because his speakers are rated for 1,250 Watts, he will need an 8.8 Amp Fuse, closest actual Fuse is 10 Amps!
Click to expand...

Can't remember the detail but I've had full rail power out from lil Cathy amp prior to WOPLing here, and the fuse saved me speaks!
 
Gibsonian said:
Can't remember the detail but I've had full rail power out from lil Cathy amp prior to WOPLing here, and the fuse saved me speaks!
Click to expand...
Ah, the dreaded "Flame Linear" or "Blaze Linear". I am so glad those days are behind us. I have often thought, what if Phase Linear had been able to figure out what the problem was with their Control Boards? Would Phase Linear still be in business?
 
I have 1 1/2 amp fuses on my ESS Heil drivers in my Rock Monitors. Maybe a bit conservative, I blow them when I get a little to "into" the music, but I'd much rather replace a fuse than a driver diaphragm. They reach well over 100 dB before blowing so that's more than enough.
 
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