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[Ampeg B15R] Following Jess Oliver's advice...

#61
JimmyM said:
Throw a Delta in there, rip out the tweeter and crossover (actually gently remove it from the circuit), and get ready to rip.
Click to expand...

This still begs my earlier question: Wouldn't this cab want a different driver if it's sealed than it would want if I do the double baffle porting mod?

Things I've read in the past have told me that a driver for a sealed enclosure is designed differently than a driver for a ported enclosure.

If I decide to do some upgrading on this combo, I don't want to buy a replacement speaker to use in it while it's still sealed and then find out I need to buy yet another driver when I do the double baffle mod.

I'm tempted to just go ahead and remove the crossover, and try my 6CA7 tubes (if I ever get them back from my amp tech). Then, at some point, I can spend the $125 for the baffle setup from FlipTops and however much for a replacement speaker.
 
#62
Well, this thread has inspired me tonight to take a big screwdriver to the back of my cab:cool:

Stu's right, it was easy to remove the crossover unit... there are a few more steps needed to get the unit out though.

On my 15R cab, there are three small black phillips-head screws located on the crossover circuit board (inside the cab). I removed these. The crossover was still connected to the cab though. Next, I unscrewed the nuts around the two full range 1/4" inputs (back of the cabinet) and removed them, along with the washers.

That did it... crossover circuit board assembly was easily removed & can now be stowed for safe keeping. I also went ahead and took off the back panel to get ready for soldering on a new jack (like so):

IMG_20130708_0105011.jpg


As you can see, there's a clear hole left where the attenuator knob used to be. That will need to be covered (perhaps with a small piece of metal taped securely inside?).

But first, I need to install a 1/4" jack. Anyone know a place with cheap shipping when ordering just a couple 1/4" mono jacks?

If not, I may just need to stop by Radio Shack - if they haven't cleared out all the electronics supply stuff to make room for more cell phones & animatronic teddy bears.
 
#63
Triboost said:
Stu's right, it was easy to remove the crossover unit... there are a few more steps needed to get the unit out though.

On my 15R cab, there are three small black phillips-head screws located on the crossover circuit board (inside the cab). I removed these. The crossover was still connected to the cab though. Next, I unscrewed the nuts around the two full range 1/4" inputs (back of the cabinet) and removed them, along with the washers.
Click to expand...

Hey! That's just what I said - except I thought it was 4 screws, not 3. ;)

Glad to see you doing this and figuring out all the tricks before I start on it myself. :hyper:

Any chance you made a recording or 3 first, so you can do another afterwards, so we can compare the sound with no crossover to the sound with the tweeter in each of its 3 positions?

Also, what soldering are you going to do on the plate? I was thinking I could get a couple of jacks and some wire and solder everything up on the bench, so when I actually go to work on the actual cabinet, all I have to do is remove the old crossover (leaving the jack plate in place) and insert the two new jacks through the holes, put on the washers and nuts, and connect the wires to the speaker. With the pre-made jacks and wires, I was thinking the swap would take about 15 minutes (or less).
 
#65
Actually, you're right... you really don't need to take that plate off! Hey it's almost 2am here. :) Although you could solder a small piece of sheet metal to cover that attenuator hole for a cleaner look.

(Or leave the whole back plate off and just dangle a wire out the back of the cab... instant bass port! I kid...)
 
#66
LOL Ya, don't leave that gaping hole in the back and make sure all holes are sealed or it'll make chuffing.

Stu, to answer your question, I don't know, but the Beta and Delta are the go-to replacement speakers for putting in old Ampeg cabs, so I see no reason why it wouldn't work. Pretty sure Bruce at Fliptops uses them in his B-15R extension cabs.
 
#67
StuartV said:
Also, do you think it will make any noticeable difference if you just leave the attenuator knob hole open?
Click to expand...
I've actually got no idea. I'm sure someone with more knowledge of cabinet physics would say theoretically, yes (interferes with the sealed cab or whatever). But these cabs are leak city around the top anyway (where the famous Ampeg "weather stripping" is).

I'm guessing it's probably no big deal - more an issue of aesthetics than anything else. And also perfectionism/peace-of-mind, which is worth it's weight in gold to me :).

Another question that comes to mind - why would anyone need two 1/4" inputs anyway? I'm thinking I'm just going to solder up one input jack and leave it at that. I never need to plug more than one thing at a time into this cab (who would?).
 
#70
JimmyM said:
BTW, I would look for sealed 1/4" input jacks so they don't leak air when both aren't in use.
Click to expand...

Yeah, I was already thinking about that. And getting 3, to put one in the attenuator hole, as well.

Triboost, the reason for 2 is so that you can daisy chain from the combo cab to an extension cab.
 
#72
StuartV said:
Yeah, I was already thinking about that. And getting 3, to put one in the attenuator hole, as well.

Triboost, the reason for 2 is so that you can daisy chain from the combo cab to an extension cab.
Click to expand...

Ah, daisy chaining... of course.

Any tips on where to find sealed 1/4" jacks? Couldn't find 'em on allparts.

Also.. noticed that the Fliptops sealed extension cab's Web product page recommends an Eminence Delta (while their recommendation for a stock baffled B15 replacement is the Eminence Beta). Confusing, especially (as Stu asks) for those of us considering doing the baffle port mod!

http://www.fliptops.net/catalog/p-100775/speaker-cabinet-1x15-b15r-b15e-style
 
#73
They're kind of close from what I hear and can make out of the specs. The Beta apparently is a little bit lower on highs than the Delta but not by much (3.7k vs 4k). I only have used the Deltas, though, so don't go entirely by me.
 
#74
Hi guys. I'm thinking about buying a B-15r. I worry that I would need more volume than it puts out sometimes.

Has anyone tried it on top of a 4x10? If so, how'd that work out?

And/or has anoyone tried the fliptops brand B-15e extension cabinet?

Thanks,
Brian
 
#75
I've tried my B-15N from 64 on a 410 before and it worked out great. 100w into a 410 is not quiet. Will it be too quiet for some? Probably. Was not too quiet for me, though. It was way louder than I need, actually.
 
#76
Ok, I went ahead and finished converting my Ampeg B15R cab (to eliminate the stock crossover/tweeter). Pics below...

IMG_20130718_1716041.jpg


The two input jacks are wired in parallel - as they should be. [Although since this amp lives at my studio, I'll probably never need to hook up an extension cab - but who knows?]

I also covered up the hole where the high-freq attenuator knob used to be. I just used a nut, a bolt and a couple big diameter/wide shoulder washers. Simple and air-tight.

A close-up here...

IMG_20130718_1716211.jpg


Next up, I'll be replacing the speaker with an Eminence Beta 15A! Stay tuned...
 
#77
Looking good! I can't wait to mod my B-15R cabinet. I bought the cab as an extension speaker for either my '63 or '66 B-15. I've taken out the original baffle with plans to mod it to the double baffle. Great to know Bruce can also make these! I'm thinking about a reconed JBL D-130/40.
 
#78
Thanks!

I just finished testing the cab using the stock speaker. Tried out a '72 Fender Tele Bass and an early '70s Gibson SG bass. Big improvement! Now I can hear the mids! That ultra-low problem is tamed too, which was the big issue I've been trying to solve.

I can even dial in a bunch of treble (via the B15r head) if I so choose, and then I'm actually getting more "picky" Rickenbacker-like tones. This has never happened before!

I think I know what happened with my particular rig. I purchased it used, and the original seller told he had disconnected the tweeter. I was aware, even back then, that this was a common mod to this amp. However, I did not know it was done incorrectly and the crossover circuitry was still in place.

So now, for the first time, I'm hearing the stock speaker without that big 3000hz low-pass roll-off (it is 3000hz, isn't it?). I recommend trying this, if you haven't already. Sounds great... can't wait to see where a tube swap & new speaker gets me next.
 
#80
Yep, it's 3000. Glad that worked out for you. I'm not a huge high end fan but I like more than 3k. 4k at the least.

So will that be it for mods or are you going full-on Fliptops?
 

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