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Just blew a cab for the first time

#82
2F/2F said:
To get decent volume without fuzzing out the tone. I set the gain like Ampeg has instructed people to do it for a long time: set it so that you can trip the peak light, but not so that it's coming on frequently. That ended up at 7:30 on the gain knob: very low. Then I set the master to get the desired volume, taking care not to go beyond 3/4 or so for fear of killing the cab. 2:30 did not provide a huge amount of volume to my ears, and 3 on the bass knob definitely was not very bassy to my mind.

FWIW, the "apparent volume" in the room wasn't anything more than what I routinely get from my B-100R. It was just a much, much cleaner and less bassy tone.
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Sorry just saw the part about where the gain was set. Gain at 7 30 and master at 2 30 doesn' strike me as particularly extreme at all even for a cab rated for 400 watts at 8ohms with a head sending potentially 400 or more watts to 8 ohms. Now I'm no expert on these matters , and it's possible that the wattage peaks you were sending were far in excess of the cab rating but nothing you've said about your amp settings seems overly egregious so, who knows? It's possible that the speaker was damaged in the store from improper use?
 
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#84
Spidey2112 said:
"Just blew a cab for the first time"

It's Sunday... I'm trying to be good.
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:D Hi Spidey

Kinda knew, you would not resist to that thread title! :laugh:

That thread title reminded me....

Well, my ex GF and I took a taxi and she...


We had to walk home!

Spidey2112 said:
They don't call him 'Wise' for nothing...
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That was not so

Wise :smug:

edit: this one comes for free!!!!
 
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#87
2F/2F said:
Obviously the cab couldn't take the amp settings I had it at; the proof is in the pudding on that. But what really confuses me is that the thing did not sound distorted before it went. The amp sounded strong but clean, and very tonally balanced – as in not particularly weighted toward any part of the tone spectrum. It was loud enough to play with a medium volume drummer, as I was doing, but not loud enough to keep up with a "real" heavy rock drummer. It sounded a rather boring tone, really. I was playing on the E string, just thinking I'd head over and monkey with the tone in a bit (I was gonna dial in more dirt/less master), and then it just blew.

I switched over to my B-100R, and it was about as loud, bassier, and very distorted. Considering the significant distortion levels I've been hammering my B-100R with for 20 years with perfect reliability, nothing about the PF-800's tone seemed to be a warning sign. Gain super low, master proportionally lower than I run it on my other amp, less low end than I normally use, way more clarity than I normally use, higher rated speaker than I normally use, not hammering the strings, etc. Just a pop, then nothing but fuzz.

I understand that I obviously blew it, but I'm trying to find where the common sense saves the day here. I actually thought I was heeding the advice I had received here and treading a bit lightly on the new setup, considering the very low amount of gain and distortion, and relatively moderate use of the bass knob (which I am used to running at 3/4 to full up, with dimed master volume on the B-100R).

Out of technical curiosity, how would two PF-115HEs handle the amp at 800W better than one PF-115HE would handle the amp at 400W? Amp wouldn't need to be pressed as hard to get the same amount of volume and low end in the room?

I've got old B-42X, B-25B, and V-4 cabs here, but after today, this amp ain't gettin' near 'em! Gonna hafta get this PF-115HE fixed before using the PF-800 again.
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Should be a good match w two of them. It'll be much fuller. And, itll still be sending the same power to the speaker. Just, to both of them this time.
 
#89
Bassmec said:
So we have discovered the thermal rating of a single 15" we used to need two of those for safe band levels.
I have always said that until physics has managed to change the melting point of pure copper significantly higher than 1048 deg c. This is still inevitably the result of lighter and smaller.:)X
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I dis like this post as I believe you missed the faliure mode. It's not the melting point of copper, it's insulating enamal coating. That is you have to worry about. The highest rating I have seen is 250 degree Celsius. That's two fifths the temperature of the copper. I have also seen glass wound copper in motors which means even hotter running motors. (Before, you question the ratio, ask your self should the ratio be based on absolute temperature or relative temperature?)
 
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#92
Well, he seems happy about it.

AF9A31E8-C0FC-4415-A8A6-5D924751261C.jpeg
 
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#93
Flamingo21 said:
Dozens of threads around here tell you not to.
You want to hear more "bass", crank the Lo Mids.
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Those are cranked too. Low mids never go below [3 o'clock] on my B-100R. It's the one tone knob on that amp that I never move. And it's no replacement for the bass knob, tonally.

At any rate, the B-100R handles it, and has for literally thousands of playing sessions since '96 or '97, when I got it new. But the point of acquiring the PF-800 was to not have to dime stuff...so I wasn't doing it on that amp.
 
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#96
Flamingo21 said:
"Nine o'clock" is not "cranked". Not by a long way.
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Never goes below *[3 o'clock]. I'll never move it lower because the tone then goes to garbage. I will often put it on 10 (as in full blast on the knob), but never moves below 9 o'clock.

Again, the B-100R seems to be doing fine, so this line is a bit of a tangent. I try to take it easy on her when I can...but I can't always.
 
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#97
2F/2F said:
Never goes below 9 o'clock. I'll never move it lower because the tone then goes to garbage. I will often put it on 10 (as in full blast on the knob), but never moves below 9 o'clock.
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I'm getting mixed up about knob location.
Mixing clock positions and scale of 10 gots me all confusified. :facepalm::help:

9 (out of 10) and 9 o'clock are way different. ;):p
 
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