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fEARful part nine (9)

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#381
rpsands said:
Yeup. That's a good starting point anyway. From what I recall I think people use a lot of different padding values; GB was using down around 1.5db or something for a while I think, and I want to say 4Mal uses as much as 4db of padding with his Alpha in the 12/6 (which would normally call for no padding).

Definitely a place in which you can experiment if you're responsible :)
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6 db is what I use.

Probably worth it to bear in mind that I was very happy with an SVT and fridge at one point so my idea of full range might be less pronounced on top that some other folks ... one you get to a certain point with htis stuff, taste enters into the picture.

BTW - GB used the words uh, gross and granularity above - and he wasn't even talking about my playing! :D

I sort of think of the active cross over in my WT-800A as the first stage of tone control. and so it's the gross IMO - getting more complicated wouldn't serve me any better. In biamp, the cab sounds as good or better than ANY rig I've owned. Any improvement is for me going to be more nuance than practical. BIG NOTE - I like it round. If it sounds good to me, it is. I'm over chasing the last infintesimal little bit of ... whatever the heck. I mean, I feel that my tone is really damned good ... so I can make more impact by re-focusing on my playing.... I know - doesn't push the cab SOTA forward but frankly it says a lot for the design work of GB and others, that for me, the rig sort of dissappears - and by that I mean - the thing sounds good enough that I hear nothing objectionable to distract me from my playing ... at this point there are no neuron's going 'jeeze I wish I had more bottom, no those are now dedicated to, for cryin' out... did you really just play that note... what were you thinking , where's 1, is that tune really in A ? ;)
 
#382
Mal, we're at the same point. If my tone is "usable" I'm done.

I agree completely with Codger's analysis of peak to average ratio. That's sticky stuff right there!

FWIW, in digital audio meant to be CLEAN and uncompressed 18dB is the common design point in headroom above average. As we shift from amplification that can deal with peaks to products with hard limits, how this is handled an issue.

Now I know why I like my seemingly total overkill solid state rig.
 
#383
Hey 4mal, that's all good to hear. Thanks! Truth be told, I've been there for the most part for a long time myself. Any changes I make are to find out more - not to seek something vaguely, or to replace something I'm not satisfied with.


rpsands said:
From what I recall I think people use a lot of different padding values; GB was using down around 1.5db or something for a while I think
Click to expand...

Yep, that was a "find out more" instance, like mentioned above. I also did 0 dB, -1dB, and from there in .5 and 1.0 dB steps all the way down to -7.5 dB (talking about 15/6 here). I found out. For me anything higher than a -1.5 dB pad made E A and B strings have trouble sounding like they were in the same universe as D G (and C) strings even when string gauges selection was tailored differently.

And ultimately, I felt that anything lower than around -3 dB was either throwing away SPL or tonal flexibility (ie I could EQ specific cuts widely if I wanted an overall drop of energy above the crosspoint without losing it all). Seems like anywhere in -2 to -3.5 dB area is where I think it's the best tradeoffs because that keeps the transition area full, off-axis.

and I want to say 4Mal uses as much as 4db of padding with his Alpha in the 12/6 (which would normally call for no padding)
Click to expand...

And now you've seen where 4Mal is currently at. I have my thoughts about this. I like that -6 dB (on 12/6) sound too. A lot actually. It's basically a good counter to what's going on in the near-field, something you can think of as Baffle Step Compensation.

But I ultimately decided not to design that way (neither has Alex at barefaced, unless he's changed this). A few reasons for that:

1) once you are out of the near field and into the larger environment, the baffle step effect has largely been absorbed/averaged out by the room response. I aim not to sound too dark or low-focused or boomy or unintelligible to a room at large. I want fEARfuls to solve problems I've heard with a lot of bass cabs that are carrying the venues and the sole stage monitor for bass guitar. And all without cranking any EQ.

2) why throw free SPL away as a global decision? You can do it with EQ cuts if you are needing/wanting that and still keep some region of the midrange driver uncut for extra personality/sonic signature. Cutting fairly wide from 800 to 1.6 K a few dB and again from 3.5K Hz is kinda cool sometime - you end up with this neat-sounding thing at 2-2.5K Hz that really works for some stuff. That's just one example out of many, not to be taken as a "greenboy always does this".

Anyway, what works for Mal is great, I can see it with the bands he's doing and the basses he likes. I had to think more of a general population that's got a little of every kind of player in it, and some clean and some distorted.
 
#384
Thanks for the various information on crest factor guys, and the elaboration on padding values.

On the latter, I definitely agree with the idea of aiming for as much usable volume as possible for the general population and correcting with eq - I'm starting to think very seriously about making a CBG crossover for my fEarful. Pretty sure I have some room to improve in there as far as the midrange driver goes.
 
#388
knuckle_head said:
I am contemplating building out a CBG 15/6 but want to put it in a rack chassis - how much room will I need? Can I get away with a 1u? Ought it be ventilated?
Click to expand...

Footprint wise, you're fine with rack mount. But those capacitors that are spec'ed are pretty sizable I don't believe they'll fit in 1U space. The same for the iron core coil.
 
#392
dug dog said:
Likely. Definitely.
Click to expand...

Definitely! The components will get warm to hot, depending on how much wattage you push through them. In the (vented) cab, the movement of air through the cab performs the cooling/dissipation function. Sealing up the crossover in a box would not be a good thing. If I were doing what you're thinking of doing, I'd put the crossover in a 2U space and have a vented/mesh panel covering the space on the front of the rack.
 
#393
New 12/6cube revision up. Redrew the 12/6cube without styrofoam in the woofer space. Took the depth down to 14.25" which leaves less space for deeper shelf retuning but also shaves some weight. It cost 21.5 cubic inches / .35 liters compared to 12/6 non-cube, where I was within 3 cubic inches before. So close ... I doubt anybody could hear the diff even with a low-tuned bass.

Try as I might I COULD NOT bring myself to make it 14" deep. I tried a number of tricks like shaving space off the internal midrange chamber and bracing, and I can get a very close phase match with other fEARfuls if I did that. But I just can't throw away that bit of extra potential that's there sonically. Console yourselves though with this: if you took off the 1.25" of "lip" and grill standoff surrounding the baffle you'd have a 13"-deep cab! All without losing the tonal authority!

One handle is all you really need on these cabs. Plan indicates this. I could have put it on the "top" but since the side could be the top anyway, I left it there, where one of those fold-out legs can do its tilt-back magic and also work like a handle. I tried that angle last night with my 12/6cube on the floor and it is just right.

fEARful%2012+6cube.png
 
#394
"if you took off the 1.25" of "lip" and grill standoff surrounding the baffle you'd have a 13"-deep cab! All without losing the tonal authority!" -GB

So you could cut off the front 1 1/4" including the front of the port? This would certainly work with the round speaker grills.
 
#396
Sweet! I have been buying components for a 12/6 cube build, but haven't cut wood yet. Nice to see a new revision just in time. I'm using one of the auction 6ND410 mids I snagged, will there be any tweaks the CBG xover before I pull the trigger on those parts? Thanks GB
 
#397
hey masonjax,

No real reason to change the crossover design. The internal volume change was so slight there's not any movement in system impedance. And no baffle placement change.

Incidentally, after getting more data from Eminence the Alphalite6A looks better than the Alpha6A, for those who aren't adding a 12sub or 15sub (who should instead look at the still undisputed champ the 18 Sound 6nd410/6nm410 and its appropriate switchable-padding crossover design).
 
#399
Sawdust starts flying here in the morning. I've finally got a couple of easier weeks schedule wise and should be done with it by Valentine's Day.

It'll be a 12/6 cube - the 1/28/11 version with a CBG crossover, Duratex and pet screen. I promise to take lots of pictures.

Thank you GB for sharing your design with us!

Who is the dealer 'o choice for Eminence?

Jim
 
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