Ampeg Portaflex PF115HE Mods

[stiles72]

Ever since I got my Ampeg PF500/PF115HE combo, I've been thinking of modding the cab to give it even more retro vibe, and to make it perform a little more like my B-100R. Recently I picked up a second PF115HE cab to make a full stack, so I'm starting my mods with the extension cabinet.

The first mod I wanted to tackle was making the PF115HE into a ported cabinet like the B-100R. I called Ampeg, and I ordered the black plastic port flanges used on the BA115. These are the same parts that were used on the B-100R and the SVT-215E cabs as well. They were out of the cardboard port tubes, so for now- I stole the ones off my B-100R and will replace those once they get some more in.

Here's some pics of the "porting" process. I used my B-100R as a reference, and I located the ports 3 1/2" in from the sides, and 3 1/4" from the bottom of the cab. I covered the back with contact paper to help protect the tolex, and I used the paper cut outs as guides for removing the insulation with an exacto knife prior to cutting the ports. The hardest part of this whole process was keeping the cab clean and vacuuming it out afterwards.

More mods to come...

Photobucket album:
Ampeg PF115HE Mods pictures by stiles72 - Photobucket

 

[beans-on-toast]

Very nice work. Looks like it was born that way. And you get two coasters out of it as well.

So what's the verdict?

 

[stiles72]

Thanks! Side by side with the sealed cab, the difference is quite noticeable. It sounds bigger, and fills the room more easily. Much more like the B-100R. Just cracking the lid open on the sealed cab doesn't produce quite the same effect. I'm going to hold off on porting the main cab until I get a chance to run them both together and see how they act in a live gig setting.

 

[GregT]

Very nice work. It's obvious that you've done some precision woodworking and planning before. Measure twice and cut once!

I just measured the inside diameter of the cardboard tubes on my B-100R. It is 3 inches. Carpet comes on cardboard rolls as does stretch film in meat departments and bakeries. I'll check something where I work tomorrow. It's a long shot.

 

[JimmyM]

Clint, I'm pretty amazed you thought it sounded more like the B100R with the ports installed because I remember the B100R as being more high tuned like a B-15. Do you still get the lows you get from the stock PF115he? Could your porting have resulted in tuning the -10db point up higher from 38hz?

 

[jackwell1029384]

subed to this thread, i'd really like to port my cab, are you going to install side handles on it? they really need them haha

 

[ddbassGA]

Put rectangular ports where you want handles and kill 2 boids.

 

[stiles72]

When I put my B-100R side by side with the stock PF500/PF115, the B-100R had a more open sound and the low end was more noticeable. The PF cab was "tighter", but you could "feel" the B-100R. I'm not real good at describing sound, but I'm pretty sure that porting the PF emphasized the low end in an "HLF" sort of way and didn't raise the tuning.

 

[JimmyM]

Pretty wild. Well you did a great job with it and it looks factory. Hope it works out for you.

 

[stiles72]

subed to this thread, i'd really like to port my cab, are you going to install side handles on it? they really need them haha

I don't think the cabs need handles when they are in "transport" mode - but they would be handy if you want to stack or move a cab that has the head in "playing" position, since there is nothing to grab onto and you just have to bear hug it. The old B15 cabs at least had side scoops to help lift the cab. If I do add side handles they'll likely be the ones they used on the B18 and other fliptops in the 60's.

I do plan to add speaker jacks to the sides of the cabs. That will be the next project...

 

[jackwell1029384]

Would you mind explaining why speaker jacks on the sides would be a good idea? I've seen a few people who want this out of these cabs but wouldn't you want them at the back so they're out of the way?

 

[JimmyM]

The original B-15's had side speaker jacks, and it looks awesome:

Invalid Link Removed

 

[will33]

It certainly did change the tuning, it changed the whole way the speaker behaves in the lows. That's not a bad thing per se. If you post the internal dimensions of the cab and the inside diameter and length of the port tubes....can find out just what you did to it, but as long as you like the sound and it doesn't fart out on the low notes, it's all good.

 

[stiles72]

No farting at all - in fact it cleaned up the low end a little bit compared to before.

Interior dimensions are roughly 20" x 19 3/4" x 19 3/4", and each tube is 5 1/2" long, and 3" in diameter.

 

[stiles72]

The original B-15's had side speaker jacks, and it looks awesome:

Invalid Link Removed

Is that just a reflection, or do you have two side jacks on the top cab?

 

[JimmyM]

Nope, Mark built it for me with two side jacks. I asked for a 1/4" to be more universal, but he really wanted it to have the 4 pin (turns out he was right to do so since it's so much better than having to deal with adapters). But he also installed a 1/4" jack. That's pretty cool if you'd want to use an SVT with them. You can daisy chain into a 4 ohm load. You'd need an adapter but I have one. Haven't done it yet, though...the B-15's too loud as it is, although our band;s volume has started to creep up there a bit. Almost running out of clean headroom on some gigs.

 

[will33]

No farting at all - in fact it cleaned up the low end a little bit compared to before.

Interior dimensions are roughly 20" x 19 3/4" x 19 3/4", and each tube is 5 1/2" long, and 3" in diameter.

That's a nice box for a single 15, didn't skimp on the size. 4.5 cu.ft. gross. Guesstimating 4.25-4.3 net, it puts your port tuning down in the mid 30's. That's a good deal lower than most. It still moves the response a good bit lower and louder than the sealed version. With the Delta 15 from having an f3 of 64hz sealed to 56hz ported. With a Beta from 54hz sealed to 49hz ported. In any case, it's more, louder bass and the extra low tuning keeps it from getting too boomy. Oddly, you don't get much for displacement limited power handling help down there, but more output so you don't have to add in as much bass.

Example: Delta sealed - 20 watts / Delta ported - 28 watts.
Beta sealed - 35 watts - Beta ported - 47 watts.

I guess as a percentage it is a pretty nice increase, just the numbers make it look low. All in all, your cabs go deeper, have more output down there, and can take some more power down there.

 

[will33]

Meh, there's a misprint in your measurements. The box is square, likely the 19-3/4 x 19-3/4 but there's no way it's that deep, so ignore my numbers there, they're all wrong.

 

[JimmyM]

Outside depth is 14.3" and the wood is 15mm thick.

 

[ddbassGA]

15/25.4 ~= .6
So 14.3 - 2*0.6 = 13.1 deep inside