Roland D-Bass 115 kappalite/ neo replacement?

[didier]

I need to replace the 15 in a Roland D-bass combo, and I'm hoping for advice on a couple of things.

some info first- This has the Roalnd "FFP" design, which has a small sensor and feedback system for the amp that is bolted to the back of the driver, and seems to work (if it does) by bouncing the beam from couple of LEDs off a reflector built in to the cone of the driver. So of course this driver isn't available from anyone but Roland, and it's close to $300. That would be less painful if it wasn't otherwise just a pretty cheap stamped frame drive.

My thought is to just disconnect/disable the "FFP" systesm, and install a standard driver. Some preliminary tests I have done suggest this will be fine- the FFP may do something great, but without it the amp still seems to run fine. If some one knows this won't work PLEASE stop me now

SO- I think I will try an Eminence neo, probably Kappalite. Internal of the cab is roughly 110 liters, with a 1" x22" (roughly) slot port on the bottom. Power will be around 250 watts.

If the kappalite is reasonable, ( I am also considerring deltalite, basslite, but haven't run any of them yet) does anyone know about the couple of dealers on ebay selling them for around $140? Everywhere else I see them around 180+, so I am wonderring if there's some difference besides price...

thanks in advance

 

[joegeezer]

BLT has the Kappalite3015 for 140.00. The driver looks like it will be good in there. Stay away from the Basslite2515, as it needs a way bigger box. I thought Greenboy would chime in on this one, but since he hasn't, i thought I would. He and several others here, have my knowledge in their toe. But I'd say it looks like the best choice.

 

[Strat]

If you go for one of the standard neo's you will be fine. I wouldn't be concerned about the casting vs stamped frame. Cast aluminum cracks, steel is flexible when dropped. Plus the Roland speaker has a great passive radiator on the back that's supposed to keep it living a long life. Although that didn't seem to work for you!

When you remove the ASC off the back of the speaker you will lose the damping function from the FPP circuit. If you think of a note's ADSR, damping affects the R or release of a note. A speaker without the ASC will not be able to signal the FPP that the speaker is possibly still moving and might need to be damped or braked when FPP is aware there is llittle or no input at the pre (such as in between notes, or the end of a passage).

I think you'll still have the start up accellerator for the speaker, as that is from the FPP sampling the input signal post preamp and it attentuates the signal during the attack portion of a note's ADSR lifetime. So little to be bothered about, especially if you play uptempo numbers. I've noticed the damping FPP in slow walking basslines, but it doesn't make that much of a difference otherwise. If it colored the sound too much, purists would avoid that line of amplification.

You have an excellent pro rig there...take care of it!

I'm surprised you need to replace....Roland does a great job of making sure the power amp won't clip, make square waves and burn your speaker's voice coil. What happened?

 

[didier]

thanks to you both for helpful info. I thought from reading other posts that the kappalite would be good for this one, and appreciate the confirmation. I even checked BLT, I don't know why but I thought they were more $ there. Thanks for that tip!

I might have been a good bit off on the internal volume, though, it may be closer to 80-85 liters. Which I guess just makes a better case for the kappa, at least compared to the basslite.

As for the ffp, I appreciate the explanation of how it functions. I'm not sure I really understand, but that's probably ok. My test involved pulling the wires from the 15 and running them to another cab I have, and it sounded ok to me, even at pretty high volume. For good measure I pulled off the sensor (ASC?) and left it loose inside the cab, which os more or less what I plan to do with it if I replace with a non-Roland woofer. Seemed fine with no signal/feedback to the ffp system from the 15.

I'm not sure about the passive radiator, maybe I misunderstand but I don't find one in the cab. (It's a 115x, the extension, and I think I said combo which maybe is different?) It seems solid all around, except for the port. Anyway, I don't know how the speaker blew, I inherited the cab in this condition, with the understanding that the speaker needed to be replaced "soon." I took that to mean more like "soonish" but now that I have played through it I think it's more like "soon" = "now." It actually sounds better at higher volumes, with less power you can really hear it scraping and sputtering.

It does seem like a great amplified cab, when I pushed it it was really punching even with the ailing driver. I'm looking forward to getting it going with a solid driver, although maybe sacrificing the ffp.

 

[Strat]

Hi, glad to hear of your choice, tell us how it sounds.

The passive radiator is really just the big cooling fins on the back of the magnet to help dissapate heat. Most speakers will avoid the costly casting for something that is rarely seen. Normally, you'd see a port in the middle of the magnet, hoping to help keep the voice coil (found on the other side of the magnet that you can't see) cool.

 

[didier]

ahhh... ok. I thought you meant passive radiator à la non-driven speaker cone functioning as a port/damper to the cab, but now I understand you mean for radiating heat from the VC & magnet.

I noticed some of the measures taken to vent and cool the voice coil and magnet on the original driver. There are some cutouts/vents in the frame between the spider and the magnet in addition to the fins on back. But, yeah, they didn't seem to quite do it. Or maybe it was some other problem, since I don't know what REALLY happened to it.

FWIW, I did completely burn up an Eminence Neo a couple of weeks ago. It was a 12" oem in a Mesa cab, and the best guess is I just pushed it with too much low end. It was only in a rehearsal, and didn't even seem that loud

 

[Strat]

Well if you're burning voice coils, then you are clipping your amps. If the speaker can handle let's say 500 watts, and you push an 100 watt amp to clip by turning it to full volume then you'll toast your speaker. I know it sounds weird since the speaker said 500 watts, and you only fed 100 watts into it.

Alternatively, if you feed 500 watts of clean power into a 100 watt speaker, you'll probably just rip it to shreds.

In order to get the most headroom before clipping always use your compressor circuit like Peavey's DDT. Know when your speaker starts to "bonk" and hit the limit of its' throw. You'll save yourselv some money!

 

[didier]

ok, I hesitate to reply and push this to the top since it escaped notice and that's probably good

that clipping blows a woofer is highly debated, but hopefully not in this thread. Whatever the truth about that is, though, I really don't think the power amp was clipping the one time I blew the speaker. Excessive power at low frequency, I have no doubt about, though. I think it just overheated and burned out before it shredded

Hopefully I'll have both replaced very soon, and have enough cone area to not have to push any one so hard. I appreciate the tips!

Well if you're burning voice coils, then you are clipping your amps. If the speaker can handle let's say 500 watts, and you push an 100 watt amp to clip by turning it to full volume then you'll toast your speaker. I know it sounds weird since the speaker said 500 watts, and you only fed 100 watts into it.

Alternatively, if you feed 500 watts of clean power into a 100 watt speaker, you'll probably just rip it to shreds.

In order to get the most headroom before clipping always use your compressor circuit like Peavey's DDT. Know when your speaker starts to "bonk" and hit the limit of its' throw. You'll save yourselv some money!

 

[Matt F]

ok, I hesitate to reply and push this to the top since it escaped notice and that's probably good

that clipping blows a woofer is highly debated, but hopefully not in this thread. Whatever the truth about that is, though, I really don't think the power amp was clipping the one time I blew the speaker. Excessive power at low frequency, I have no doubt about, though. I think it just overheated and burned out before it shredded

Hopefully I'll have both replaced very soon, and have enough cone area to not have to push any one so hard. I appreciate the tips!

How did it go? I know this is a very old thread, but the reason I ask is I have two D-bass 115's that I use with a Geddy Lee 2112 preamp, and I've been thinking about upgrading the drivers to Kappalite.