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15/6 Tube
- Thread starter Tractorr
- Start date
FF trails off much less below 100hz than others but suffers with a 97dB starting point for it.
If you lose 3dB sensitivity anywhere really important, like 80 to 150hz, your last 3dB of headroom goes with it. This isn't a problem if you had 12dB of headroom and used only 9dB of it. But if you had 9dB and used it all you are in for a disappointment.
Everybody knows FF goes lower and mids are omnipresent. I think it's a great design but it isn't that great when watts are scarce. I would want to try one out before pulling the trigger, it's not hard to do in the US.
Another option, put your 3015's in a JohnK "Starliner", optimal tuning, lightweight braced 1/2" ply design.
If you lose 3dB sensitivity anywhere really important, like 80 to 150hz, your last 3dB of headroom goes with it. This isn't a problem if you had 12dB of headroom and used only 9dB of it. But if you had 9dB and used it all you are in for a disappointment.
Everybody knows FF goes lower and mids are omnipresent. I think it's a great design but it isn't that great when watts are scarce. I would want to try one out before pulling the trigger, it's not hard to do in the US.
Another option, put your 3015's in a JohnK "Starliner", optimal tuning, lightweight braced 1/2" ply design.
I'm interpreting Bill's quote somewhat differently; that is the loss in a low level (between the preamp and power amp) passive crossover is where the level loss lives.
I'm also seeing a different point that Bassmec is making - if one is trying to use tube amplification to get to high volume, highly efficient speakers are in order. Current designs like the fearful are not anywhere as efficient as something like an Altec 421 in a horn.
OK, math time. Throw +27 dBW (500 Watts) at a fearful 15/6, and you get 124 dB at one meter. Put +20 dBW (100 Watts) into one of those Altec in a horn monsters and it is good for 129 dB at a meter.
The two cabinets will not sound at all the same, but the point is that there is a place for highly efficient designs.
I'm also seeing a different point that Bassmec is making - if one is trying to use tube amplification to get to high volume, highly efficient speakers are in order. Current designs like the fearful are not anywhere as efficient as something like an Altec 421 in a horn.
OK, math time. Throw +27 dBW (500 Watts) at a fearful 15/6, and you get 124 dB at one meter. Put +20 dBW (100 Watts) into one of those Altec in a horn monsters and it is good for 129 dB at a meter.
The two cabinets will not sound at all the same, but the point is that there is a place for highly efficient designs.
- May 9, 2008
- 4,081
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- Disclosures
- Proprietor Springvale Studios
Yes you have done the math perfectly, quite a large difference isn't it.
I am a big fan of Ampeg V4b and other 4 output tube 6l6/EL34 amps and I can power soak the 100 watts in studio with ease but I still want to gig with one and I still want it very loud and clean.
I therefore am a forced to collect loads of old Altec Lansing, James B Lansing, Electrovoice EVM S short basket version, ATC PA75's. ETC.
Get enough of that list stacked up high and wide you can knock the place down with 100 tube watts and have all the dispersion and VLF you can use in the hall.
It's like there are two totally disparate technologies here, one is very effective at getting a very small light cabinet to make just as much sound as a very big one. All you need to make this Idea work fantastically well is to feed it a huge bag of watts.
So as you had originally decided that 15/6 Fearful's are now ideal for use in loud gigs with Tube amps, I was suggesting a sensible choice of tube amplifier for that exact job:
Invalid Link Removed
Well don't just stand there laddie! get a fork lift!.
Still. Missing. The. Point.
Using your logic everyone with a tube amp should be running stacks with [Invalid or Expired Link Removed] sensitivity. Or better yet use a bunch of these with [Invalid or Expired Link Removed] sensitivities. They would be incredibly loud with minimal power.
Oh wait, they may not meet the tonal needs of many bass players. You are also missing the point that a player using a 100 watt tube head may not always use that same amp.
If "loads of old Altec Lansing, James B Lansing, Electrovoice EVM S short basket version, ATC PA75's" work for you thats great. For my tonal goals they are terrible regardless of the amp being used.
Lol I did answer him that I do not have the capability to take the measurements. I suggested that as a studio proprietor he supply us with that info after building his own cab.
Outrageous? So is asking me to buy equipment.
Yes, you are very well sorted. I loved reading about you getting your guitarist playing through a POD and mixing everyone through your 1515/66 at rehearsal.
Hmm.....3 pages and no specs....well, here.
You take one of these. http://www.eminence.com/speakers/speaker-detail/?model=Kappalite_3015LF put in roughly 110 L net volume ported box, tuned to approx. 47 hz.
You pass that off via passive 12db/oct. crossover to one of these Link Removed at approx. 750hz.
With no padding, that would be something like 98db below 750hz and 102db from 750hz to approx 5khz or so.
I believe the single 15 fearfuls use 3db worth of padding on that hot mid driver, so, 99db on the high side.
Using a small amplifier, allow a couple/few % for insertion loss. For a large amplifier, cut the thermal limits of the respective drivers in half to allow for power compression, (3db).
And there you have it.
You take one of these. http://www.eminence.com/speakers/speaker-detail/?model=Kappalite_3015LF put in roughly 110 L net volume ported box, tuned to approx. 47 hz.
You pass that off via passive 12db/oct. crossover to one of these Link Removed at approx. 750hz.
With no padding, that would be something like 98db below 750hz and 102db from 750hz to approx 5khz or so.
I believe the single 15 fearfuls use 3db worth of padding on that hot mid driver, so, 99db on the high side.
Using a small amplifier, allow a couple/few % for insertion loss. For a large amplifier, cut the thermal limits of the respective drivers in half to allow for power compression, (3db).
And there you have it.
There actually was somebody who crossposted a response measurement they took of their fearful. May not have been calibrated and could've used a little smoothing, but basically showed a gradually climbing response, though fairly smooth, with the top of the mid driver giving a lift around 2-4khz.
The fearless lines use a bit smaller enclosure, (though still very deep LF extension), and more notch filtering/smoothing applied to the 6" driver. A sort of more refined system that seems I would quite like.
Though I am still exploring sealed woofer designs with guitar drivers carrying the top side. Not so refined...rather rough....and pretty.
The fearless lines use a bit smaller enclosure, (though still very deep LF extension), and more notch filtering/smoothing applied to the 6" driver. A sort of more refined system that seems I would quite like.
Though I am still exploring sealed woofer designs with guitar drivers carrying the top side. Not so refined...rather rough....and pretty.
So I was reading through Bass Gear and remembered they posted this.
Link Removed
There you go, honest to goodness SPL response chart on/off axis, done by a third party.
Link Removed
There you go, honest to goodness SPL response chart on/off axis, done by a third party.
This may be long.
The power compression and loss due to the passive network are rather over exaggerated. The .163 ohms resistance from the coil for the 3015lf is not going to attenuate much at all.
As for the power compression. All speakers experience it, so it is not really fair to even add it to this comparison. But since it was brought up...
1)Conventional 2x15's and 4x10's have no where near the midrange response of the fFEARful. They experience a high roll off of the upper mids starting from 800hz up. They also do not have the response from 150hz down. This means that you will have to boost these freq's 3-6db to achieve the same response as the fFEARful using conventional cabs. It takes power to do this, adding to the power compression in conventional cabs. This means that with the low watt tube amps, the fFEARful will have the advantage. Even with the Greenboy dually and basic designs, although, not quite as much as the drivers used are substantially better than the usual run of the mill bass cab manufacturers.
2) Power compression is a result of the heating of the voicecoil. Since the compression specs are not listed by Eminence, the only guage we have are the thermal power specs. For the Kappalites this is quite high as they are extremely efficient motor assemblys. Much more so than old ceramic speakers. The thermal capacity of one high power kappalite is equal to twice that of the speakers usually used in bass cabs. This means that even though there are more drivers in conventional cabs the effects of power compression are about the same.
3) What freq range are the listed sensitivity measurements taken? This is an old argument to the home brew builders, and a just one. Who knows which speaker that 104db @1 watt is referring? Most tens have a sensitivity of 95-96db from the manufacturer, but even then it is a narrow pass band, not the entire response. As you can see from the posted response of the 15/6, the fearful design is flat. That 99db sensitivity is for almost all of the the listed freq response. In this sense the fFEARfuls are equal to the conventional designs, and beat out most of the 2x or 3x designs.
4) Horn cabs. Really? Isn't exactly apples to oranges, but ok. Not only are they going to be huge to reproduce the lows, but they have some severe draw backs. They are tuned to a freq. band meaning their full range response is compromised from the start. Next, even within the tuned pass band you are going to have anomalies, as the throat is the perfect environment for standing waves. The only way horns are a good choice is if you have multiple cabs for the different pass bands. If the negatives to horn implementations are not apparent, well.....
It has been listed before, and here it is again. Off axis response is incomparable to conventional designs. They weight 1/2 to 2/3's less. It is just hard to find a reason not to use one, other than you already spent money on something else and cant afford to do it right now(the boat I am in...), you stand right in front of your cab, you sit on the floor in front of your cab, you don't have time to work out so you like carrying 100+ pounds for blocks and up stairs, your daily driver is a flat bed semi, you own stock in a company that produces conventional cabs, you have a sponsorship, etc...
The power compression and loss due to the passive network are rather over exaggerated. The .163 ohms resistance from the coil for the 3015lf is not going to attenuate much at all.
As for the power compression. All speakers experience it, so it is not really fair to even add it to this comparison. But since it was brought up...
1)Conventional 2x15's and 4x10's have no where near the midrange response of the fFEARful. They experience a high roll off of the upper mids starting from 800hz up. They also do not have the response from 150hz down. This means that you will have to boost these freq's 3-6db to achieve the same response as the fFEARful using conventional cabs. It takes power to do this, adding to the power compression in conventional cabs. This means that with the low watt tube amps, the fFEARful will have the advantage. Even with the Greenboy dually and basic designs, although, not quite as much as the drivers used are substantially better than the usual run of the mill bass cab manufacturers.
2) Power compression is a result of the heating of the voicecoil. Since the compression specs are not listed by Eminence, the only guage we have are the thermal power specs. For the Kappalites this is quite high as they are extremely efficient motor assemblys. Much more so than old ceramic speakers. The thermal capacity of one high power kappalite is equal to twice that of the speakers usually used in bass cabs. This means that even though there are more drivers in conventional cabs the effects of power compression are about the same.
3) What freq range are the listed sensitivity measurements taken? This is an old argument to the home brew builders, and a just one. Who knows which speaker that 104db @1 watt is referring? Most tens have a sensitivity of 95-96db from the manufacturer, but even then it is a narrow pass band, not the entire response. As you can see from the posted response of the 15/6, the fearful design is flat. That 99db sensitivity is for almost all of the the listed freq response. In this sense the fFEARfuls are equal to the conventional designs, and beat out most of the 2x or 3x designs.
4) Horn cabs. Really? Isn't exactly apples to oranges, but ok. Not only are they going to be huge to reproduce the lows, but they have some severe draw backs. They are tuned to a freq. band meaning their full range response is compromised from the start. Next, even within the tuned pass band you are going to have anomalies, as the throat is the perfect environment for standing waves. The only way horns are a good choice is if you have multiple cabs for the different pass bands. If the negatives to horn implementations are not apparent, well.....
It has been listed before, and here it is again. Off axis response is incomparable to conventional designs. They weight 1/2 to 2/3's less. It is just hard to find a reason not to use one, other than you already spent money on something else and cant afford to do it right now(the boat I am in...), you stand right in front of your cab, you sit on the floor in front of your cab, you don't have time to work out so you like carrying 100+ pounds for blocks and up stairs, your daily driver is a flat bed semi, you own stock in a company that produces conventional cabs, you have a sponsorship, etc...
What kind of tube heads? i am having a hard time with my YBA300 and early distortion onset with the 12/6/1
The first problem is your running an impedance mismatch. The 12/6/1 is an 8 ohm cab. The YBA300 make 300W at 4 or 2 ohms. Since your running the amp at 8 ohms, it will only make 250W.
The next issue is the sensitivity of the woofer in a 12/6/1 is only 95.5dB. That's 2.9dB lower than the woofer in the 15/6...and (IMHO) a single 15/6 is still in the relatively low efficiency range. Basically a single 12/6/1 is not a very good choice for your amp IMHO.
If you run another 12/6/1, you will gain 3dB in sensitivity due to mutual coupling, and the amp will make an extra 50W because it is seeing the correct impedance impedance. The net gain in SPL will be about 3.8dB. It's still not going to be super loud. IMHO a pair of 15/6/1 would probably make you a lot happier, as that would get you a 6.7dB boost.
Jim Carr
Dr. Jim
- Jan 21, 2006
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- fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
I've recently started using my Mesa Prodigy tube head again with a 12/12/6/1. I tried it live about a year ago a couple of times and didn't get the power I needed for a large club with a crappy PA. In retrospect, I think perhaps it was gain staging and a quirky upright pickup causing the preamp in the Mesa to clip.
Now, every Wednesday, I am in a small lounge playing blues with a band that invites others to sit in after the first set. Yes, a 200 watt tube head into a large 12/12/6/1 fEARful is sort of the bass amp definition of classic nuclear overkill (to obliterate (a target) with more nuclear force than required).
Yet, the Prodigy sounds absolutely great! At various times at this regular, I've been playing passive Fender Jazzes, a couple of different P-basses, and a truly great 2007 Nash Jazz relic with DiMarzio pickups. It has been a great chance to experiment with aforesaid instruments, EQ, compression (EBS, Barge, MDX, etc.), and preamp pedals (Sadowsky, Sansamp paraDI, etc).
n.b., the Prodigy is 200 watts @ 4 ohms, and the 12/12/6/1 is 4 ohms. The other bassists are pretty much either fEARful/Fearless users, or are totally blown away by the sound of the Prodigy/fEARful rig.
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Jim Carr
Dr. Jim
- Jan 21, 2006
- 16,223
- 7,613
- 76
- Disclosures
- fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
Thanks for that!..Well, i made the mod in the head so I can switch it between 8 and 4 ohms..so I will be running the full power..I have also switched out all the preamp tubes, which got me a bit more headroom (not much) but mostly cured some obnoxious mids from the amp...I have also disconnected the tweeter and am running the Lpad on the mid driver...that helped somewhat.
Still, for instance friday night at a not very loud gig I was running the amp gain about a third of the way, and master volume about half, and was getting more distortion than I like..
Back in april I messaged 'vbchaos' on here as he was having the same problem, and had stopped using the amp..Just yesterday I got A reply which was interesting--Quote "
Problem with the combination of the YBA300 and a fEARful was (for me) that the YBA has not enough clean power. The tube break-up comes quite early (which is part of the design), but the fEARfuls handle distortion very differently than any cab you might know (that is because you have a 2-way system).
When I pushed the Amp the only thing that really got harder was the harmonics in the mid-range speaker, while the body of the sound wasn't there.
I discussed this on the fEARful forum through and through. It was not for nothing that Dave Green designed the 15/6 TUBE. The 15inch speakers have a better SPL at same power input. The 12s just do not move enough air on low Watts."..he also went on to mention that he had used the amp with other cabs and it was fine...
So I really don't know at this point if it is an intolerable coupling of amp/cab, or this is strictly a problem with the cab breaking up quite early and that mid driver really accentuates that?
Thank you, I was wondering that myself..Seeing as vbchaos indicated this amp sounded fine with other more generic cabs, I really don't know at this point if I blew 2000 bucks on this amp or its a speaker problem.
