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Ampeg b15 live tone

bluehevy75

bluehevy75

Dec 1, 2007
397
146
Chicago, IL
#1
I love my late 60's blue line b15n (theile cab). I also play a 78 p bass with big flats and a foamy mute.

I play in a soul band, seven piece: keys, horns, drums, vox, guitar, etc. We play medium size bars with 80-100 people. We play play at a moderate volume (obviously, I'm using a 30 watt amp). Guitar player plays a 40 watt tube amp. You get the idea.

I love that low-mid thumpy sound.

Lately, as the crowds have gotten larger and the venues have switch from small bars to medium bars, I've seen my volume come up. As I've brought the volume up on the b-15n I find myself rolling off the bass control on the amp. Like, all the way off. Last night the treble control was on 1 and I rolled the bass control all the way off.

It makes me nervous. Like I'm not actually hearing it correctly or maybe the sound is very different by the time it hits the audience and I've over eq'd. Does cutting that much bass seem right?

At low volumes I have no troubles it sounds heavenly. But when I push that amp I feel like the bass goes through the roof--too boomy. I'm not rolling off any tone on the p-bass. I run it wide open.

Discussion? Ideas?

Attached find the curve for the speaker and a pic of my amp.

Thanks!
 

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#2
Maybe a high pass filter like the Thumpinator or FDecks' HPF?

When I read about speakers laboring or reacting strangely to loud volumes, I think of high pass filters and getting the speakers to use what power they are getting the most efficiently.

And that is a general problem with B-15 setups; they don't go as loud as many need for live situations.
 
#4
Weird. I always add bass on mine when I crank it. But I say if it's working for you to roll bass off, do it. Or get a V4B ;)

Will a different speaker help? Maybe. What are you using?
 
#5
I'm using a Jensen Neo 150. It is the theile cab though Jimmy.

You've got the double baffle right? Not sure what effect volume has on the different speakers/cab designs.

I've never had the head serviced. I don't know if that would make a difference or not either.

I've got v4 with 2x15 for bigger shows...I dime the low-mids...but I really work hard to use the b15 whenever possible. I have a certain amount of pride (whether right or wrong) at squeezing every watt I can out of that little amp. Plus I don't want to have "creeping loudness" disease. If I've got extra watts on stage I'll be tempted to use them.
 
#6
I'm not an audio engineer, but it has been my experience that A). Most bass amps need a bass boost from wherever "Flat" is on their controls. B). Bass frequencies dissipate more readily throughout the room. This means that, while it may feel like you are rattling fillings out of teeth when you're three feet from your rig, you are probably actually producing a pretty balanced amount of low-end out in the room. Unfortunately, this may also cheese off more whiney band members who aren't using IEMs but live in a fantasy world where they think the stage mix should be as quiet and clear as the FOH mix, especially if you're not running everything through the PA. C). Most commercial bass cabinets don't really produce a lot of true low-end, and instead have bumps in the low-mid frequency range that give the bass much of its body. D). If you're moving to larger clubs and audiences, I'd be worried about running out of headroom quickly with a 30w amp - even a tube amp - if you don't have PA support. The audience is going to be absorbing a lot of sound. You may want to start using that V4 more. ;)
 
#8
bluehevy75 said:
I'm using a Jensen Neo 150. It is the theile cab though Jimmy.

You've got the double baffle right? Not sure what effect volume has on the different speakers/cab designs.
Click to expand...
I used to have a Thiele cab B-15N with a CTS in it. Had considerably more low mids than my double baffle. When I cranked it, though, it seemed to me like it started rolling off the bass, but it's been a few years since I had it, so I'm going off memory.
 
#9
JimmyM said:
I used to have a Thiele cab B-15N with a CTS in it. Had considerably more low mids than my double baffle. When I cranked it, though, it seemed to me like it started rolling off the bass, but it's been a few years since I had it, so I'm going off memory.
Click to expand...

So weird….I'd read about Jamerson cranking the bass too while live and I couldn't figure it out.

At "volume" it starts moving so much air that my pant legs start flopping around even with the bass control rolled off. I'll switch to channel two and see what happens.

Don't ge me wrong. I like bass. But I don't like mud so I'm just trying to dial in a articulate sound. Not bright….just nice defined lows.

The more I ponder this and your responses I believe it is a) how close I stand to the amp at some of these shows (literally right on top of it…small stages) and b)maybe it needs work.

Would new tubes in the pre-amp stage change anything? I bought this thing used 10 years ago and have no idea what work has or has not been done to it over the years.
 
#10
The damping on the back wall of the cabinet removes some of the mud. Maybe you can try adding a little more material (mattress foam or dense spun polyester from a fabric store) to see if this helps clear it up at high volume levels. If you have an old blanket or something similar, that could work. It's a simple test and might be worth a shot. Too much damping can be a problem. You have to find a balance that works.
 
#11
I'm assuming with a 7 piece soul band and a crowd of 100, the B-15 is just a stage monitor.
If not, the main concern is what does it sound like in the house which I would assume to be very quiet.
If it is just a stage monitor, it doesn't sound like the right amp for your application if this happens consistently.
OTOH, I've had amps that sounded great on stage and throughou the house PA at one club, and sounded horrible on stage at others either do to being placed in a 90 degree corner with masonry walls, hollow stage, or odd shaped rooms.
You HAVE to sound great out front, and being inspired by your tone on stage is important but not the primary concern IMO.
 
#12
Blue, sounds like you might be happier with an Altec 421a. Half the reason I sold mine is because it had a CTS in it, which in the 70's was a rather dark speaker. Sounded awesome in the low mids, but had no treble and very reduced high mids. I tried the Delta 15a I have in my double baffles, but while it had treble, the box design scooped out the mids too much. The guy who bought it with the CTS really digs the reduced treble, though, and guys like Justin Meldal-Johnsen keep their Thiele cab B-15's with the CTS in them, so it's all good. But if I'd have kept it, no doubt by now I'd have put a 421a in it. More high mids and treble with it. Wish I knew of a modern day equivalent that doesn't cost as much as a vintage Altec, but I don't.
 
#13
bluehevy75 said:
So weird….I'd read about Jamerson cranking the bass too while live and I couldn't figure it out.
Click to expand...
Food for thought, from experience with two-band preamps, ie bass and treble. Simply put, a way to increase mids with some circuits, is to cut bass and treble. Intuitively, my response is that given the specific characteristics of your rig, different from those of others, in the context of your band, in the rooms you play, you are doing what works. In your case, rolling back bass and treble may be akin to boosting mids, which cut through the mix.

You have experience with your other amp, so we assume that you know what your rig should sound like. Maybe ask a knowledgeable person about your tone in a given room. Or, stroll to the back, enabled by a wireless connection, and hear for yourself, assuming that your amp is producing bass sound, and not PA.
 
#14
The mention of the Altec 421A here brings up a question regarding this speaker. I have one (that was thrown in (for free), on a deal on a pair of Altec 418Bs). It has a badly torn cone. I would appreciate any opinions on having this thing re-coned. Are these worth the cost to re-cone? I see the spec sheet lists it as being 17 pounds, but every time I move this thing it seems to become heavier. I would not pay to ship it to be re-coned. There is a local guy around here, who would probably do it, but this guy is not so easy to deal with. I have always wanted to try my hand at this, but now is not a good time for me to learn, or experiment with speaker re-coning. If I got this for free, is it worth maybe a hundred bucks to have it re-coned? Would it be worth a try in a double baffle B-15 cab? (I've got two B-15 cabs. One, with a JBL, and one with a Jensen, so I don't really need this speaker, but it is not doing any good without a cone). If I have the local guy do it, it will be with whatever kit he chooses. The original voice coil, and aluminum dust cap are good. Should I just have this guy replace everything, with whatever kit he decides he wants to use, or is there a certain kit that is best to use?

Thanks for any opinions on what to do with a damaged Altec 421A.
 
#15
P Town said:
If I got this for free, is it worth maybe a hundred bucks to have it re-coned? Would it be worth a try in a double baffle B-15 cab? (I've got two B-15 cabs. One, with a JBL, and one with a Jensen, so I don't really need this speaker, but it is not doing any good without a cone). If I have the local guy do it, it will be with whatever kit he chooses. The original voice coil, and aluminum dust cap are good. Should I just have this guy replace everything, with whatever kit he decides he wants to use, or is there a certain kit that is best to use?
Click to expand...

If you have no need for it now you can always store it away for a time down the road.

When you recone, you have to change all of what they call the "soft parts", which includes the voice coil and dust cap. There is some info here. There is a video link that shows how to perform a recone that's interesting. You'll see what I mean about the need to change all the parts.
 
#16
Thanks for the link, Mr. Beans.

I have a lot of stuff stored away for future use. The future comes, and other priorities seem too often to take precedent over the things I would like to occupy my time in the present. I just hope that I live long enough to enjoy some of the more interesting material possessions I have accumulated over the years. Once I acquire something, I don't usually get rid of it. I would love to attend the auction that my kids will have to hold to dispose of my stuff when I kick off. I would probably only buy half of my stuff though, so someone else may have to fix that speaker. Maybe some day I'll sell it to fund 15 seconds worth of care at the Shady Rest old folks home.
 
#17
I know what you mean. At some point in life you realize that you won't have time to do everything that you wanted to. You have to pick and choose what's most important with the time that you have left to bring peace and happiness.
 
#19
I have a '64, double baffle, original square magnet driver, that I love but have resigned myself to the fact that it just isn't practical for anything but home practice and jams, and occasional studio work. I suppose it would work for jazz, coffeehouse, and other light duty stuff but it weighs a ton. Why risk busting a disc and/or ruining a classic when a walkabout and 1x15 or even 1x12 will get you 90% of the tone with 300% the volume/headroom and 50% of the weight. It's gotta be a very special occasion for me to haul that baby around.
 

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