Pioneer 8" B20

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Pioneer B20 8"

I have ordered these speakers for the Godzilla Piezo project so while I wait I have some questions. What rots the foam surround on speakers? Is it humidity-time-heat? Is there a certain "life" expectancy on foam surrounds?
The other question regards spl for the B20...I am building 4 sealed cabs sized 1.6cf with a rear facing Piezo.They will be mounted near the corners facing slightly down and towards the middle of our game/party room. Will they be loud enough for the odd blowout in a 18LX18WX9H space? I shall run them with a 10" powered subwoofer. The amp is a NAD.

bring on 08,
Cheers
 
Destroyer, whats you basis on damaring, removing the whizzer and not installing the piezo if running a subwoofer? It don't make much sense to me. Just a little more info might clear my confusion.

WORS, whats above your ceiling? Is it the attic or is this room in the basement? It you have the attic above, you could put the speakers in the ceiling at the four corners with a baffle that comes down a bit to point the speakers towards the middle of the room but still keep the front sealed from the back. This would be an infinite baffle setup then.
 
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I am not sure what baffle size would be best. I am running them in a open box that was around 2 cubic feet which I did not design to be ideal, just found I preferred it a lot over a closed box.

The damaring helps a lot, it really gives it some control. This is basically giving it treatment that a lot of drivers like paper cones get from the factory, that it lacks. The speaker was simply made with cheap foamish paper but you are correcting the softness.

The whizzer cone is too weak and the highs that is pretends to give off are weak and not very entertaining, really just creates some counter muttering noise. I find no lack of any high frequency's as far as my taste goes without it, and what it does do sounds a lot more accurate.

Both modifications increased (in a 2 channel setup) imaging, transparency, and accuracy on a scale of I would not want the speakers without it, like I would buy something else, kind of way. They also have the capability for some more impact with the less flimsy cone. Drums and guitars can give you some umph you feel.

I just consider the piezo sort of a waste of time myself, I tried it with lots of resistors and found it never really to add much (the territory is not filling in much to begin with after damar on B20). I would think a horn or sorts would be more appropriate if you want to be loud.

If you are running a subwoofer open baffle / semi open / infinite works nice. I just find there is not enough low extension in the B20 for my taste.

I think the ceiling mount idea would be ideal in this situation as the other fellow mentions. You get infinite baffle, probably low problems with canceling wave forms, and could look nice.
 
Greets!

Well, from just measuring the whizzer and looking at PE's response plot, it has a ~900 - 5 kHz BW, so this will be attenuated somewhat, reducing 'shout' and some of the BSC off-set required at the expense of severe beaming, so my SWAG is a 2nd order around 7 kHz, which just happens to be a good point for a 3.5" piezo horn.

GM
 
WORS said:
How tough is it to remove said whizzer and am I not better off leaving it alone and "painting" dammar on the whole deal. btw how do you aply the dammar-soft brush? Do you do both sides?
I believe Planet 10 mentioned NOT to do both sides for some reason, perhaps adding to much weight and doing more harm then good, but IDK...


GM said:
Greets!

Well, from just measuring the whizzer and looking at PE's response plot, it has a ~900 - 5 kHz BW, so this will be attenuated somewhat, reducing 'shout' and some of the BSC off-set required at the expense of severe beaming, so my SWAG is a 2nd order around 7 kHz, which just happens to be a good point for a 3.5" piezo horn.

GM
So how well do you think the Pioneer will perform wizzerless and with a phase plug? I have been considering going that route for a while now, and treating the cone somehow, maybe eNaBle...I would be happy with extension to 7-8khz and just cross a tweeter around there...
 
Removing the DC will kill much of what's left of its extreme HF response, which is a good thing IMO if a super tweeter is used. Some years ago on the original FR forum at least one person gave his a whizzerectomy and swapped out the paper DC for an aluminum one cut from the bottom of a soda can IIRC to make a poor man's JBL LE-8H, but don't recall if he added a super tweeter capped off way up high or not. Anyway, IIRC he did some selective doping using both French? Shellac to stiffen and Dammar to damp and was pretty pleased with the results, decreeing it was about as good as could be expected considering the 'sow's ear' he'd started with.

All things considered, better to just buy a better driver at this level of tweaking unless you're doing it as a hobby and prepared to turn them into woofers if things don't pan out.

GM
 
GM said:
Removing the DC will kill much of what's left of its extreme HF response, which is a good thing IMO if a super tweeter is used. Some years ago on the original FR forum at least one person gave his a whizzerectomy and swapped out the paper DC for an aluminum one cut from the bottom of a soda can IIRC to make a poor man's JBL LE-8H, but don't recall if he added a super tweeter capped off way up high or not. Anyway, IIRC he did some selective doping using both French? Shellac to stiffen and Dammar to damp and was pretty pleased with the results, decreeing it was about as good as could be expected considering the 'sow's ear' he'd started with.

All things considered, better to just buy a better driver at this level of tweaking unless you're doing it as a hobby and prepared to turn them into woofers if things don't pan out.

GM
Well they are in Half Changs, so I can always go with Fostex if things don't work out, the drivers are so cheap that I don't feel bad playing with them :D
 
GM said:
Agreed, the only 'el cheapo' driver with more tweaking interest over the years AFAIK has been the 40-1197, RadioShack's 'el cheapo' version of the Fostex FE103.

GM
I almost bought some to play around with still in boxes, but decided to just use my money for the B20s. Kinda regret not picking them up...

That EnABLE thread is massive...seems easy to apply though..do people usually add the dammar first then EnABLE? Or only do the latter? Gonna have to do more reading...
 
I haven't followed it since even on the best day of my life I wouldn't have had the patience to do a pair, so don't have a clue what all prepping may be required. My version was to use a mechanic's stethoscope to crudely map the diaphragm (no two alike) and use an airbrush to spray on whatever was required to get the job done.

GM
 
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