Full Range 4 Ohm 15" Driver Availability and Options

[yakmastermax]

*Flame suit on*

Hey guys. I'm trying to find a stand alone 15" driver for a custom box. I'm looking for standalone options that will sound good without a horn or midrange driver. I'd like something with power capability and lows (5 string capable). Sensitivity/efficiency is also an issue, I'm shooting for as much sensitivity as possible. An Eminence 3015 would be perfect except that they only make them in 8 ohm versions and I need a 4 ohm driver (vintage head). Box will be around between 3.75 cubic feet and ported. My budget caps out at $250 dollars but I'd prefer cheaper because money is tight

It is weird; there are plenty of high quality 4 ohm 15" subwoofer drivers like the 3015LF-4 and Delta-15LF-4 but the only full range 4 ohm 15" driver I've found is the Legend CA15-4 but I'd like something with more sensitivity, power handling, and Xmax.

I'm also wondering why exactly the 15" subwoofer drivers are not suitable for standalone use? Between the 3015 and the 3015LF there is only an octave more of frequency response. Does this really make the difference? There are tons of 4 ohm options if I include these subwoofer drivers...

How would a cabinet sound with 1.5 kHz of maximum frequency response. How would a cabinet sound with 2.2 kHz of maximum frequency response?

Also way out in left field If anyone knows of any high quality sealed back midrange drivers in 4 ohms that might be an option.

Thanks guys!

 

[CL400Peavey]

Is the box already built/ported?

 

[yakmastermax]

Is the box already built/ported?

Built, not ported yet. More like 3.8 cubic feet. I wanted to port to the specifics of the driver.

 

[CL400Peavey]

Built, not ported yet.

Hmm... How did you decide on size with out a driver in mind?

 

[yakmastermax]

Hmm... How did you decide on size with out a driver in mind?

I'm aware that it isn't ideal but I thought most drivers have a cubic foot or two of wiggle room when it comes to vented enclosures. The port tuning relative to the internal volume and the box shape was what "closed up" the last variable. For example the 3015 is recommended across a 4 cubic foot spread for vented enclosures because you can tune a usable resonant frequency in at any volume within that spread.

Yeah yeah I know I'm real stupid.

Would like to hear some driver suggestions.

 

[CL400Peavey]

You might take a look at the 15PR400, shoot for a 45hz tuning.

 

[yakmastermax]

Oh man the Faital looks killer. drool It is really pushing my budget though.

I took a look at the response graph for it and it is showing 80 dB sensitivity at 4kHz.
The $90 eminence legend CA154 is showing 90 dB sensitivity at 4kHz.
Both have basically the same curve from 20Hz to 2kHz except the Faital is vertically offset across the board by about 5dB which makes sense since it is a more sensitive driver overall.

Both drivers have comparable Xmax but the Eminence is almost $180 dollars cheaper and is made stateside AFAIK which is a big plus to me. The Faital is more than twice as loud across the board as far as I can tell though...

I'm still a little confused since the Faital claims the 15PR400 has a 35Hz to 4kHz response and the Legend CA154 is spec'd at 45Hz to 3kHz. When I analyze the response graph myself though it seems that both have comparable response curves just with the Faital being louder across the board. Is there a particular dB sensitivity at which a driver stops being "useful"? Analyzing the response curves at 90dB for both I see that the CA154 spreads from about 65Hz to 4kHz while the Faital goes from 40Hz to 2kHz and that 2kHz is being generous. This also seems at odds with the information from the spec sheet and the pricing. At a particular volume (90dB) the cheaper driver can go an octave higher and the more expensive driver can do about about an octave lower.


I know that the Delta 15LF-4 is one of these low frequency subwoofer drivers that isn't meant to be used stand alone but how is this distinction determined?

The response graph for the Delta LF shows 90 dB from 70Hz to 3kHz... which is half an octave more top than the $260 "full range" Faital

My dad says I often have my head up my ass and I fear this may be one of those situations...

I understand that my comparison is banking on the curves all being similarly linear but looking at another sensitivity such as 70dB yields a similar result. The Delta LF spans 25Hz or so to 5kHz and the Faital spans 20Hz to a little more than 5kHz.

Quick look at the 3015LF-4 at 90dB shows 60Hz to 3kHz, at 80 dB I'm seeing 35hz to 4kHz

Really looking for some help guys

As always, thanks TB

 

[AlexanderB]

It is weird; there are plenty of high quality 4 ohm 15" subwoofer drivers like the 3015LF-4 and Delta-15LF-4 but the only full range 4 ohm 15" driver I've found is the Legend CA15-4 but I'd like something with more sensitivity, power handling, and Xmax.

For a given cabinet (the one you have), the deep bass extension and system sensitivity will counter balance each other. So you will have to chose more lows capable drivers (generally meaning higher Xmax) or higher sensitivity drivers (giving up on the maximum potential output of deep bass).
This is all very fundental, and you really should have either by reading up on basic stuff, or by making a list of design targets BEFORE you build something at all.
In the end, picking two 8 Ohm, 10" woofers should probably be a smarter way of doing this, as you would get a much larger section to work with, still reaching a good result from the $250 budget.

 

[jnewmark]

You might take a look at the 15PR400, shoot for a 45hz tuning.

+1. The best full range, 4 ohm 15 out there, imho.

 

[5StringPocket]

I'm also a fan of the 15PR400 but either driver would work for this application. The Faital will handle more power but also cost more so if budget is a primary concern I'd just get the Legend CA15-4 and build the medium vented design shown at the bottom of this link. http://www.usspeaker.com/images/Legend_CA154_cab.pdf

Follow the recommended size and tuning. Don't deviate and forget about subwoofers unless you are prepared to include a mid driver and 2-way crossover. Sub-woofers have heavier cones with more travel which puts out more lows but the tradeoff is that they don't have the extended upper mids a full range driver has.

 

[yakmastermax]

For a given cabinet (the one you have), the deep bass extension and system sensitivity will counter balance each other. So you will have to chose more lows capable drivers (generally meaning higher Xmax) or higher sensitivity drivers (giving up on the maximum potential output of deep bass).
This is all very fundental, and you really should have either by reading up on basic stuff, or by making a list of design targets BEFORE you build something at all.
In the end, picking two 8 Ohm, 10" woofers should probably be a smarter way of doing this, as you would get a much larger section to work with, still reaching a good result from the $250 budget.

Could you please fill me in more on how deep bass extension and system sensitivity counter balance one another?
I don't quite see how low capable drivers necessarily have low system sensitivity. I've been reading as much as I can on T/S parameters and to me Xmax is a physical measurement which linearly corresponds to the total volume of air the driver can displace. It is essentially the clean controlled maximum physical amplitude of the oscillating cone. Large volume displacement is necessary for effective bass frequency reproduction but the Xmax T/S parameter is essentially included in the dB vs frequency graph. The result of a larger or smaller Xmax is driver capable of more or less dB SPL and so the effects of the Xmax parameter are included in the response graph.

I'd very much like to list out design targets but unfortunately I'm not familiar with how bass guitar tone and sound correspond to particular frequencies. I understand that the first fundamentals of most of the notes on the neck extend from 40Hz to maybe 640Hz but of course this isn't the full story. Accurate reproduction of the overtones and partials is absolutely necessary for a good bass cabinet but I don't know what frequency ranges these important overtones and partials exist within. I would love some education on the subject but the information is hard to find.

I appreciate your suggestion but the box is done and I decided on the single 15" a while back. Maybe next box will be a 2x10 box.

+1. The best full range, 4 ohm 15 out there, imho.

Thanks jnewmark, your and CL400Peavey's suggestions have been duly noted and I'm confident with your combined assessment that the Faital is the best full range 4 ohm 15" available. Now I'm trying to deepen my understanding of drivers so that I can determine the best full range 4 ohm 15" in terms of value Because the bottom line is that I'm a poor college kid lol.

I'm also a fan of the 15PR400 but either driver would work for this application. The Faital will handle more power but also cost more so if budget is a primary concern I'd just get the Legend CA15-4 and build the medium vented design shown at the bottom of this link. http://www.usspeaker.com/images/Legend_CA154_cab.pdf

Follow the recommended size and tuning. Don't deviate and forget about subwoofers unless you are prepared to include a mid driver and 2-way crossover. Sub-woofers have heavier cones with more travel which puts out more lows but the tradeoff is that they don't have the extended upper mids a full range driver has.

Thanks 5String. The 15PR400 currently is at the top of my list with the CA15-4 in second (big price jump, wish there was something in between).

Could you please explain further why subwoofer 15"s are simply not an option without a mid driver?
I don't see how cone weight contributes to better bass frequency reproduction. I do see the importance of travel (Xmax) but I don't see how larger Xmax detracts from full range capability.

Looking at the frequency response graph for the Faital upper mid response from 2kHz to 5kHz (this is upper mids right?) shows 90dB to 70dB respectively.

The 3015LF from 2kHz to 5kHz shows 97dB to 65 dB. The eminence is producing 70 dB at 4.5kHz however.

The Delta LF across the same frequency span produces 96dB to 70dB. Assuming linear behavior between the data points the Delta LF has the same upper mid response as the Faital!?

As always thanks guys.

 

[CL400Peavey]

The 3015LF from 2kHz to 5kHz shows 97dB to 65 dB.

This isnt a stand alone driver, so you can cross it off the list with out further consideration.

 

[5StringPocket]

Could you please fill me in more on how deep bass extension and system sensitivity counter balance one another?
I don't quite see how low capable drivers necessarily have low system sensitivity. I've been reading as much as I can on T/S parameters and to me Xmax is a physical measurement which linearly corresponds to the total volume of air the driver can displace. It is essentially the clean controlled maximum physical amplitude of the oscillating cone. Large volume displacement is necessary for effective bass frequency reproduction but the Xmax T/S parameter is essentially included in the dB vs frequency graph. The result of a larger or smaller Xmax is driver capable of more or less dB SPL and so the effects of the Xmax parameter are included in the response graph.

I'd very much like to list out design targets but unfortunately I'm not familiar with how bass guitar tone and sound correspond to particular frequencies. I understand that the first fundamentals of most of the notes on the neck extend from 40Hz to maybe 640Hz but of course this isn't the full story. Accurate reproduction of the overtones and partials is absolutely necessary for a good bass cabinet but I don't know what frequency ranges these important overtones and partials exist within. I would love some education on the subject but the information is hard to find.

I appreciate your suggestion but the box is done and I decided on the single 15" a while back. Maybe next box will be a 2x10 box.



Thanks jnewmark, your and CL400Peavey's suggestions have been duly noted and I'm confident with your combined assessment that the Faital is the best full range 4 ohm 15" available. Now I'm trying to deepen my understanding of drivers so that I can determine the best full range 4 ohm 15" in terms of value Because the bottom line is that I'm a poor college kid lol.



Thanks 5String. The 15PR400 currently is at the top of my list with the CA15-4 in second (big price jump, wish there was something in between).

Could you please explain further why subwoofer 15"s are simply not an option without a mid driver?
I don't see how cone weight contributes to better bass frequency reproduction. I do see the importance of travel (Xmax) but I don't see how larger Xmax detracts from full range capability.

Looking at the frequency response graph for the Faital upper mid response from 2kHz to 5kHz (this is upper mids right?) shows 90dB to 70dB respectively.

The 3015LF from 2kHz to 5kHz shows 97dB to 65 dB. The eminence is producing 70 dB at 4.5kHz however.

The Delta LF across the same frequency span produces 96dB to 70dB. Assuming linear behavior between the data points the Delta LF has the same upper mid response as the Faital!?

As always thanks guys.

Simply stated, you can't have it all. There are tradeoffs. A subwoofer has a longer travel, often slightly heavier and more rigid cone to prevent breakup, and larger voice coil for more effective length in the gap and higher heat dissipation. These help produce high levels of low freq SPL but at the cost of reduced efficiency (more watts/dB). You have to move a lot more air for the same SPL at low freq which takes more energy - think of a diesel truck vs a sport coupe. The truck will outpull the coupe but can't go as fast. The subwoofers with this kind of construction also have more rigid surrounds and a higher inductance, both of which attenuate high frequency reproduction. When there is no real content above 2000 Hz the speaker will sound very dark - maybe OK for reggae but for general use you won't like it. There is a wealth of information on speaker operation and design if you search. You can go as deep as you like but I wouldn't overthink a project like this. In the meantime, if you want your box to sound good with minimum investment, use one of the full range drivers already recommended and tune the box properly. You might also try WinISD, Boxsim and some of the other freeware simulations out there to test your own designs. They are typically useful for just the bass response - use the vendor curves over 500 Hz.
Barefaced Bass - Technical Information
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[BassmanPaul]

Why a 1x15 with a 4Ω driver? 8Ω makes much more sense.

 

[B-string]

Why a 1x15 with a 4Ω driver? 8Ω makes much more sense.

You know that answer.

To get all those watt thingies out of my amp to fry voice coils, don't care if it get loud as long as the watts numbers are there.

 

[Passinwind]

Why a 1x15 with a 4Ω driver? 8Ω makes much more sense.

Not if you own a vintage amp with only a 4 ohm output transformer tap, as the OP apparently does.

 

[Marko 1]

...and I need a 4 ohm driver (vintage head).

 

[Marko 1]

Is the ability go reproduce that low frequency fundamental all-that important?

My Markbass classic 2x15 cab - 50 Hz to 20 kHz (to 5 kHz with horn off) - and my open B sounds great.

 

[AlexanderB]

OK; yakmastermax, while I still say you are doing things the wrong way, I will fill you in with some more data (in the same line given by the other posters, too).
As mentioned, high SPL, deep bass in moderate size enclosures calls for a long stroke (Xmax), rigid (read heavy) cone, low Qts (read powerful magnet and voice coil) to take advantage of the venting, plus a robust surround for linear motion at high excursion.
A speaker uses the current from the amp to move the cone. The magnet field and voice coil gap will act as a "springboard" for the current/magnet force through the voice coil. A good coil to coil gap ratio will transfer a percentage of the current into a motion = high sensitivity. The thing is, that the longer voice coils needed for high Xmax in sub woofers will have more Windings outside the voice coil gap, so less energy is converted to motion, and more to heat. Look up an exploded view or cross section view of the motor assembly to see how different a car subwoofer (sensitivity in the 85 dB range) is from a HF driver (with 105 or so dB).
In the end, when in a correct box, and powered with HIGH power levels, the dedicated subs will still outperform "regular" woofers or full range drivers for maximum output IN THE LOWEST REGISTER, nowhere else.
So that is sensitivity vs extension.

For tone: all the other factors usually found in subwoofers; heavy cone, high inductance and high mass voice coil, robust surround etc will be detrimental to buth clarity and extension of the mids.

So again, I really suggest you rethink what you are doing - especially if you have a (low power) tube amp with the 4 Ohm tap. There is no way you will take benefit of any technical solutions chosen in modern, high power (sub-)woofers. Either you find a pair of modern MI 8 Ohm drivers and get a high sensitivity, medium power, full range cainet. If not, you will have to accept that there very few "raw" 15" 4 Ohm drivers that will do a good job.
One more driver you could consider is the 4 Ohm version of the old Cerwin Vega 15" driver used in PA and bass cabinets through the 80s. Nothing fancy, but fairly robust, cast frame, deep bass, nice sounding for bass (in my opinion), 4 Ohms and easily available from reconing shops or second hand. It is lower sensitivity than the same era "bass" speakers from EV and JBL, but goes deeper.

By the way, I am not sure about how you have determined the bass extension of your candidate drivers? The "unloaded driver" charts provided by some manufacturers are useless below a couple of hundred Hertz. To understand the final result of driver + cabinet, some sort of modelling software (or manual calculations!) is needed.

 

[5StringPocket]

Is the ability go reproduce that low frequency fundamental all-that important?

My Markbass classic 2x15 cab - 50 Hz to 20 kHz (to 5 kHz with horn off) - and my open B sounds great.

Not really as long as it's strong at the first overtone. Sealed cabs which roll off early sound good on stage because the low end is tight and controlled. Some of it is personal preference but you don't want a stage rig that fights with FOH.