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Ampeg Portaflex PF115HE Mods

#41
JimmyM said:
That was some good cipherin' there. You musta studied your gazintas. You could be a double-naught spy!

jethro.jpg
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You had me stumped for almost a day with "gazintas". Then I remembered, 9 gazinta 54 6 times, 6 gazinta 18 3 times, etc.
 
#42
stiles72 said:
Yes, typically I leave the horn off on the bottom cab. I'll leve it on the middle setting for the top cabinet - but sometimes find that I like the way it sounds with it off as well.

When I add the speakon jack to the side of the cabs, I'm planning to wire it directly to the 15" driver itself. That way, it can act as a "vintage" voice - so that the 15" receives a full range signal like what you typically have in non-horn cabinet, bypassing the internal crossover of the main jack plate. Or, it could also be used as a way to connect both cabinets together. The head can connect to the top cab business as usual through the back jack plate so that the horn could be used. The speakon would then daisy chain the top 15" to the bottom 15", bypassing the bottom cabs horn and jack plate.

I'll probably use the standard 4-pin round Neutrik, but I kind of like the look of the silver jack.
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I'm not sure if it applies to your mod or not, but you might want to look into this:
agedhorse said:
Not sure how you have your jack switching configured, but beware of backfeeding the low pass section of the crossover (ESPECIALLY if it's second order). It needs to be switched out of the circuit one way or another.

The reason for the caution here is that if you look into the speaker from the LF driver's terminals (and not from the normal input configuratin), a second order filter will have a shunt cap across these terminals and some amps may explode (yes catastrophically) when presented with such a large illegal load. It's also because there may exist a resonant tank circuit (one that stores energy as a phase shifted signal in an inductor-capacitor network) and these too can cause disasterous effects.

The effect may or may not be an issue with first order filters, but it would be prudent to isolate everything else from the woofers if this kind of full range operation is desired.
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As a side note to anyone wanting to add ports to your cabinet but are unsure of your jigsaw skills, hole saws are available at home centers. These saws, while they may be a little pricy, make the job very easy. Just make sure that the hole saw you buy is deep enough to cut all the way through the plannel being cut.

holesaw.jpg
 
#43
Vintage-Blue said:
You had me stumped for almost a day with "gazintas". Then I remembered, 9 gazinta 54 6 times, 6 gazinta 18 3 times, etc.
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Mark, the reason you were confused is that Jimmy isn't redneck enough. We down home boys know that it's spelled goesinta, instead of gasinta, as in:
"Those wires don't plug into the goesintas, they plug into the goesoutas". Peace, Jimmy. :smug:

Edit: That should have read, "Us'uns down home boys". :D
 
#44
stiles72 said:
I wasn't too worried about doing this mod, since I was basically just copying what Ampeg has done on other models. And, I figured if I screw it up - it's not like it's a rare vintage piece. My only concern was what would happen if the jig saw hit a knot in the wood or "got away from me" and went off course.
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I sometimes have that angled cut problem as well when cutting with a jig saw. I thought it happened to me when I ran the saw too slowly. I agree with Mark about using a router. I've found that I do a better job when I use one (I have a DeWalt DW618 plunge router). The big advantage is that you can control the depth of the cut. Makes it easier to avoid accidents when the blade doesn't extend into the box. If it broke, the blade could have flew into the speaker.
 
#45
John D said:
As a side note to anyone wanting to add ports to your cabinet but are unsure of your jigsaw skills, hole saws are available at home centers. These saws, while they may be a little pricy, make the job very easy. Just make sure that the hole saw you buy is deep enough to cut all the way through the plannel being cut.
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I've used these as well with very good results. If you start the cut on one side, not going all the way through, you can finish the cut from the other side and get nice clean edges.
 
#46
beans-on-toast said:
I've used these as well with very good results. If you start the cut on one side, not going all the way through, you can finish the cut from the other side and get nice clean edges.
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Using David's two-sided approach also makes it easier to get the plug out of he hole saw, and enables the use of a too shallow hole saw, in case yours isn't deep enough. The key to using either of these methods is to make sure that the saw teeth are held parallel to the surface being cut.
 
#48
John D said:
Mark, the reason you were confused is that Jimmy isn't redneck enough. We down home boys know that it's spelled goesinta, instead of gasinta, as in:
"Those wires don't plug into the goesintas, they plug into the goesoutas". Peace, Jimmy. :smug:
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Didn't look very hard, did you, wisenheimer?

Urban Dictionary: gazintas

Gazinta AND guzinta are both accepted spellings according to the dictionary. I know my stuff...I've had a 6th grade education.

:p
 
#50
I was not sure about the new PF cabs when I bought a PF 500 head, and have held off on buying any of the new PF cabs. So I have cobbled my PF500 into the speaker of a B100R that I keep in the bedroom. I also have run my B-12-XTC through the B100R speaker, (4 Ohms, so I only tried it briefly, with no evidence of extra heat, or light from transformers, or tubes), and it sounds great at the low volume I play there. This was easier, and cheaper than porting a new cab.
 
#56
beans-on-toast said:
I sometimes have that angled cut problem as well when cutting with a jig saw. I thought it happened to me when I ran the saw too slowly. I agree with Mark about using a router. I've found that I do a better job when I use one (I have a DeWalt DW618 plunge router). The big advantage is that you can control the depth of the cut. Makes it easier to avoid accidents when the blade doesn't extend into the box. If it broke, the blade could have flew into the speaker.
Click to expand...

It happens because you're putting more forward pressure on the blade than the saw can keep up with. It can't chew out the wood fast enough, the extra force has to go somewhere, so the blade flexes sideways. Running the blade fast, but cutting slow, actually helps the problem.
 

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