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Ampeg Portaflex PF115HE Mods

#21
That was some good cipherin' there. You musta studied your gazintas. You could be a double-naught spy!

jethro.jpg
 
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#22
JimmyM said:
Outside depth is 14.3" and the wood is 15mm thick.
Click to expand...

Aahhh......that sounds much more like it.:D Works out to ball park 2.88 gross...guessing 2.75 net..tuning in the neighborhood of 42hz. Sounds more like it looks to me, something didn't seem right back there.

It actually helps the performance. Woofers would fartout too early in the big box.

Delta ported / -3db @ 64hz, +3db @ 110hz, disp. limit 44 watts @ 87hz.

Delta sealed / -3db @ 70hz, +2db @ 125hz, disp. limit 34 watts @ 60-70hz.

Beta ported / -3db @ 59hz, +5db @ 100hz, disp. limit 73 watts @ 85hz

Beta sealed / -3db @ 60hz, +3db @ 105hz, disp. limit 56 watts @ 70hz.


Anyway, same relationships apply, he's given them a little deeper output and play a little louder down in the bottom. I know you say the Delta's sound like the Ampeg drivers, but, ampeg stuff I've played, which hasn't been much in the way of 15's seem to handle things a bit better than the numbers make it look. Wondering if their OEM maybe something like a Delta voicing that can take a little more in the lows. Oddly enough, the lowend rolloff slopes look fairly similair in all 4 of those models. Yoh don't get the gradual slope of the sealed vs. the steep drop of the ported. They look sort of in between and real similair.

Anyway, if it sounds good and doesn't fart out, it's good. Some good looking mod work by the OP, they look factory.
 
#23
The only thing that would really concern me about this modding is the Beta's 5db boom hump in it's ported version. The other 3 are in that area that gives them some heft but doesn't screw up the sound. A touch of a bass knob will flavor them either way.
 
#26
will33 said:
Anyway, same relationships apply, he's given them a little deeper output and play a little louder down in the bottom. I know you say the Delta's sound like the Ampeg drivers, but, ampeg stuff I've played, which hasn't been much in the way of 15's seem to handle things a bit better than the numbers make it look.
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That may be. Never put a Delta in a 115e. And the Deltas certainly don't sound like the speakers in the PF115he. The specs would bear that out, since the PF115he's 3db down point is 50hz. Without Stiles' port mod, the 10db down point is 35hz.

Wondering if their OEM maybe something like a Delta voicing that can take a little more in the lows.
Click to expand...
Ya, it's not identical to the Delta voicing but the cab does have more upper mid than you'd expect in a cab that goes down to 35hz.
 
#27
JimmyM said:
That may be. Never put a Delta in a 115e. And the Deltas certainly don't sound like the speakers in the PF115he. The specs would bear that out, since the PF115he's 3db down point is 50hz. Without Stiles' port mod, the 10db down point is 35hz.


Ya, it's not identical to the Delta voicing but the cab does have more upper mid than you'd expect in a cab that goes down to 35hz.
Click to expand...

Those numbers are more in line with an OEM take on the Legend CB158 hitting them in that small a box, in which case the displacement limit power handling would be at least 4 times higher than the Delta.
 
#31
I noticed in one of your pictures that your horn is turned off. Do you usually run it like that?

Here's a picture of a cardboard tube that has an internal diameter of 3 inches, but the outside diameter is 3 3/8ths. The hole in a B-100R is only 3 3/16ths. I hope Ampeg gets the tubes in pretty quick for you.
 
#35
Every time I undertake a big modification I get this sick feeling in my gut after the first irreversible turn in the journey. What have I done? I'm wondering if you felt like that Clint.

I find that if you don't try things you never learn. In the end, if you think it through before you start, it usually turns out much better than expected.
 
#36
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.

I started a project a while ago to make a 2x15 Powerflex cabinet for my Oliver head, and I had trouble cutting the the top opening with the jig saw. The cut appeared to follow the lines when viewed from the top, but underneath - the blade had shot way off course, cutting on an angle. I tried several different blades and settings, and took my time. In the end I attributed it to the cheap plywood I was using - since it cuts fine on everything else. Someday I'll get back to that project.

But for good measure on this PF - I made a couple of test runs on scrap wood just to be sure before I cut these ports, and it went as planned.
 
#37
GregT said:
I noticed in one of your pictures that your horn is turned off. Do you usually run it like that?

Here's a picture of a cardboard tube that has an internal diameter of 3 inches, but the outside diameter is 3 3/8ths. The hole in a B-100R is only 3 3/16ths. I hope Ampeg gets the tubes in pretty quick for you.
Click to expand...


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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#38
I know Jesus will be weeping ;) - but I went ahead and ordered handles. I went with the chrome handles found on the B18, B12XT, and BT cabs just for some extra bling. The originals were made by a company called Kason, and they are still in business. They actually still make the very same handle - although it's part # has changed from 577 to 573. Fliptops does offer these, but I found a deal on another site that had them priced for less: Kason 573 Offset Pull Handle at BARefrigeration.com


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#39
stiles72 said:
I started a project a while ago to make a 2x15 Powerflex cabinet for my Oliver head, and I had trouble cutting the the top opening with the jig saw. The cut appeared to follow the lines when viewed from the top, but underneath - the blade had shot way off course, cutting on an angle. I tried several different blades and settings, and took my time. In the end I attributed it to the cheap plywood I was using - since it cuts fine on everything else. Someday I'll get back to that project.
Click to expand...

If you do much work like this a router can be an invaluable tool for making a clean, square cut. You can make a cheap template of the opening you want and then use the router with either a template bit (bearing on top) or trim bit (bearing on bottom). I lay the template on the piece of wood and use a pencil to trace the cut. Next I use a jig saw to rough cut the opening, staying off the line about 1/8". Then I put the template back on, using clamps or double-face tape to hold it in place, and use the router to finish the cut.

I'm currently making new cabinets for my Oliver OP-1s and I'm using this process to cut the rectangular openings I need. Here is the back panel from one of them:

temp2.jpg


Here is the template that I just made to cut out the two openings:

temp1.jpg


Rectangular templates are really easy to make out of scraps of plywood. You just need to cut 2 pieces (in my case 3) to the length of the opening and glue them between 2 side pieces, making sure to space them apart the distance of the height of the opening.

If, however, this is a one-time deal it can be tough to justify the cost of even a cheap router and bit just to cut one opening.
 
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#40
stiles72 said:
I know Jesus will be weeping ;) - but I went ahead and ordered handles. I went with the chrome handles found on the B18, B12XT, and BT cabs just for some extra bling. The originals were made by a company called Kason, and they are still in business. They actually still make the very same handle - although it's part # has changed from 577 to 573. Fliptops does offer these, but I found a deal on another site that had them priced for less: Kason 573 Offset Pull Handle at BARefrigeration.com


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Click to expand...

It's good to see another source for those. They're also available from McMaster-Carr at a slightly higher price: p/n 1656A1 $12.41.

One note on the new handle. You will sometimes see the vintage handles turned up and sometimes see them turned down. You could do that with the old handle because the casting was solid all the way around. The new handles really need to be mounted turned down, since they have a hollow on the underside of them.
 

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