Your opinion on Fuse speaker location

[famousg]

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....

 

[George S.]

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/

 

[mlucitt]

All Phase users fit a support fuse on the loudspeaker input.

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.

 

[Skratch]

Years ago before DCP relays I fused my speakers with my 400. Kept me from blowing speakers when I got drunk or stupid

 

[FredR]

Years ago before DCP relays I fused my speakers with my 400. Kept me from blowing speakers when I got drunk or stupid

I did as well. No more. Thanks Don!

 

[mlucitt]

Kept me from blowing speakers when I got drunk or stupid

You don't have to be drunk or stupid to turn your system up to Mach 10, eh Lee?

 

[laatsch55]

Correct, I can do that plumb sober....

 

[mr_rye89]

Fuses at the outputs cause distortion anyways......

 

[Gepetto]

Fuses at the outputs cause distortion anyways......

Not if you use the special fuses Kyle, and install them in the correct direction.

 

[laatsch55]

Oh yeah .....those 2,000.00 dollar fuses..

 

[62vauxhall]

Oh yeah .....those 2,000.00 dollar fuses..

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".

 

[Gepetto]

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

Doggone, it is out of stock...

 

[Gibsonian]

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.

 

[Gibsonian]

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.

 

[mlucitt]

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.

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!

 

[Gibsonian]

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!

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!

 

[mlucitt]

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!

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?

 

[laatsch55]

No...
Poorly run business...
Then the bean counters took control and all was lost..

 

[Gepetto]

No...
Poorly run business...
Then the bean counters took control and all was lost..

Imagine what it would have been if they were building the amps of the quality that this team is putting out now...I think, perhaps a different story.

 

[Vynuladikt]

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.