Does anyone have any experience with using passive radiators for musical instruments? I was thinking of building a passive radiator box for my bass to keep the box small and get good lows from a 12" speaker.
The radiators I've seen are all foam surrounds and I'm thinking I'll be blowing the cones into the grill cloth 1st big notes I hit.
Why would I want to do this? I have a bassman with the crappy oxford 12" and I want to replace them with something that will give me good 40Hz response. The bassman box is very small, but it fits in my Camry, which is nice. Otherwise, I'll just replace the oxfords with a pair of eminence basslite 12s for about $160US.
The radiators I've seen are all foam surrounds and I'm thinking I'll be blowing the cones into the grill cloth 1st big notes I hit.
Why would I want to do this? I have a bassman with the crappy oxford 12" and I want to replace them with something that will give me good 40Hz response. The bassman box is very small, but it fits in my Camry, which is nice. Otherwise, I'll just replace the oxfords with a pair of eminence basslite 12s for about $160US.
You will not keep the box "small" since the PR is the same as a port. You need the same size box as you would with a ported box with the same driver... maybe you can "squeeze" a little, but the main advantage to the PR is easier tuning. Otoh, if you use a 12" bass speaker, you want an 18" PR!! You can get away with a very very high linear throw PR at a smaller diameter, but it will be almost impossible to get away with a 12" PR... IF you use a HP (lo cut) filter below say 30Hz in your rig that makes it a bit easier all the way around... no extreme LF excursions (like when you slap?) to handle...
Getting 40Hz response will require some combination of power handling, surface area and box size. The max SPL you need dictates the surface area/power handling and then the box size - obviously it is easier to get low bass at lower volumes. Live gig volumes require something like the eminence higher power handling drivers and a boat load of power to permit some EQ to get the sense of low bass... but that still depends on the room size and the loudness you want/need.
sorry to say there is no box that fits in the trunk of the Camry that will fill a BIG room with loud bass... if there was it would be a product already.
Also, those boxes and drivers get heavy, fast... 🙁
Your best compromises will come by using a simulator and plugging in T/S parameters and looking at the EQ requirements, your power available (the amps) and the SPL max + headroom...
It gets complex fast.
So, if you have just a Bassman head, get the highest sensitivity driver you can with the best power handling, and hope it sounds ok in your box...?
No simple solutions for this...
_-_-bear
Getting 40Hz response will require some combination of power handling, surface area and box size. The max SPL you need dictates the surface area/power handling and then the box size - obviously it is easier to get low bass at lower volumes. Live gig volumes require something like the eminence higher power handling drivers and a boat load of power to permit some EQ to get the sense of low bass... but that still depends on the room size and the loudness you want/need.
sorry to say there is no box that fits in the trunk of the Camry that will fill a BIG room with loud bass... if there was it would be a product already.
Also, those boxes and drivers get heavy, fast... 🙁
Your best compromises will come by using a simulator and plugging in T/S parameters and looking at the EQ requirements, your power available (the amps) and the SPL max + headroom...
It gets complex fast.
So, if you have just a Bassman head, get the highest sensitivity driver you can with the best power handling, and hope it sounds ok in your box...?
No simple solutions for this...
_-_-bear
I've not thought about using it this way but I'll think you'll find that due to the nature of a PR system that the box size can be made smaller than your average ported. Maybe even as small as the sealed would be, hence the advantage in using them.
Cal,
With serious EQ and HP filtering, yes, but then you need one of those 2kW power handling speakers to reach practical SPLs...
So at that point, why not just EQ and HP use an ultra high power handling speaker in a small box (get the T/S as best as possible too) and find urself a 3lb 2kW digital amp, skip the PR??
So, I'd just go with regular speakers... for live playing you can't have too small of a box and expect bass SPL, there's no way around it.
It's like asking if you can get thunder bass out of an 8" woofer - Carver tried, right? 😀 The max SPL is an issue...
_-_-bear
With serious EQ and HP filtering, yes, but then you need one of those 2kW power handling speakers to reach practical SPLs...
So at that point, why not just EQ and HP use an ultra high power handling speaker in a small box (get the T/S as best as possible too) and find urself a 3lb 2kW digital amp, skip the PR??
So, I'd just go with regular speakers... for live playing you can't have too small of a box and expect bass SPL, there's no way around it.
It's like asking if you can get thunder bass out of an 8" woofer - Carver tried, right? 😀 The max SPL is an issue...
_-_-bear
I tried getting 28Hz out of a pair of 8"s - they run out of excursion very fast...
I'm not sure about the PR idea - they're widely available, so why doesn't the industry use them?
Perhaps it's because ports take up a smaller area of the front, leaving more space for drivers...
I'm not sure about the PR idea - they're widely available, so why doesn't the industry use them?
Perhaps it's because ports take up a smaller area of the front, leaving more space for drivers...
Most commercial PR using designs consist of dumb application, which results in less than optimum operation, which in turn results in less than fantastic consumer satisfaction. And they cost more than ports by a wide margin... I think that sums it up pretty much...
There's a saying: "no free lunch"
_-_-bear
There's a saying: "no free lunch"
_-_-bear
I would have to agree with bear. There are a few really bad examples out there that have probably done a lot of perceptual damage to the concept.
I myself would never have given them a second thought until I recently picked up an old pair of JVC floor standing speakers with them in it (for free even!).
If this old pair of beaters is any indication, then you definitely do not want to give up on the idea. The quality of the bass really makes you sit up and take notice. The towers each have a single 8" woofer in them, and a 9x12" rectangular PR. You would swear there was also a subwoofer hiding somewhere in the room, filling in the bottom octave. It's quite amazing.
I'm definitely going to look in to building a PR cabinet for my own bass rig.
You can also use several PRs if you can't find a single one that's big enough... I've seen several boxes with the driver on the front, and a PR, same size as the driver, on each side.
I myself would never have given them a second thought until I recently picked up an old pair of JVC floor standing speakers with them in it (for free even!).
If this old pair of beaters is any indication, then you definitely do not want to give up on the idea. The quality of the bass really makes you sit up and take notice. The towers each have a single 8" woofer in them, and a 9x12" rectangular PR. You would swear there was also a subwoofer hiding somewhere in the room, filling in the bottom octave. It's quite amazing.
I'm definitely going to look in to building a PR cabinet for my own bass rig.
You can also use several PRs if you can't find a single one that's big enough... I've seen several boxes with the driver on the front, and a PR, same size as the driver, on each side.
One of the other advantages a passive radiator does have is when the speaker parameters and desired response, maybe after mainly attempting to minimize overall size, call for a particularly small box and large/long tube. You can get to the point where a PR can actually make you a reactive loaded speaker that you can't otherwise have without putting the port on the outside of the box. (which doesn't actually take any less total volume, or necessarily become smaller either) If you're not particularly inclined to choose one or the other depending on ability to select passive radiator damping (which I think is pretty rare) or worry about things like whether you prefer suspension distortion over that of turbulent air and other funny noises that make their way through the port but not so much through a PR cone, there's hardly any difference, other than ports are cheap.
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There is a minor advantage to the PR vs. port below the resonant frequency of either. The PR acts more like a sealed box below the resonant frequency...
_-_-bear
_-_-bear
well, maybe if you are talking exstremely small compact "cube" design
or maybe also very BIG designs
but in a normal cab the woofer usually takes up all the space
I dont see the space saving anywhere
edit, actually I thought a PR would be for very low tuning, which apparently isnt needed
and I may have another doubt about a PR with bass guitar, how does it sound 😕
or maybe also very BIG designs
but in a normal cab the woofer usually takes up all the space
I dont see the space saving anywhere
edit, actually I thought a PR would be for very low tuning, which apparently isnt needed
and I may have another doubt about a PR with bass guitar, how does it sound 😕
The instance where a pasive radiator fits in a box and a port wont can be explored by taking a driver that might work well in a small ported box and looking at what happens if you compound load them or suddenly slap a much bigger magnet on it (drop Qts). Start with drivers having Qts below .3 in a woofer simulator and have a look. Particularly with drivers having very high excursion capability you need a port volume that just wont go unless you hang it outside the box, especially if you demand a high level of efficiency and low noise. It may not be well known because the -3dB point starts rising fast when Q falls too much which is not the usual end result for a sub, and phase and group delay starts getting really weird if you arbitrarily make the box too small and try to drag the tuning down which ultimately defeats all purposes. However, despite all the lore or uninformation about PRs, a PR can save space. The effect on volume can be really great because even though the PR basket has to be somewhere it takes up minimal internal volume compared to a high diamter port.
Because very low Q is not what usually gets the sound in instrument speakers anyway there is a good chance that very few people have explored running a PR on bass drivers in the interest of saving box volume. The boxes are big and required ports easily fit because driver excursion is average or low. A relatively modest PR could handle at least one driver of same diameter and maybe 2. A high performance PR of larger diameter could handle many bass drivers. With a large box and large enough port it is practically impossible to beat the fundamental distortion and efficiency performance with a PR, not accounting for box "noise" coming out of it, which might be a serious problem to consider since an instrument speaker is obviously not a subwoofer. On that basis alone a PR could be superior.
Because very low Q is not what usually gets the sound in instrument speakers anyway there is a good chance that very few people have explored running a PR on bass drivers in the interest of saving box volume. The boxes are big and required ports easily fit because driver excursion is average or low. A relatively modest PR could handle at least one driver of same diameter and maybe 2. A high performance PR of larger diameter could handle many bass drivers. With a large box and large enough port it is practically impossible to beat the fundamental distortion and efficiency performance with a PR, not accounting for box "noise" coming out of it, which might be a serious problem to consider since an instrument speaker is obviously not a subwoofer. On that basis alone a PR could be superior.
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I've dorked with PRs in "too small boxes" quite a bit. What you can get is some bass extension vs. just a small box, since the port will usually just not tune worth a darn... but the output of the PR is down some dB... however when you listen to it, it can never-the-less sound "good" even though if you measure it is does not measure particularly well.
I think what may make it sound halfway good is the presence of a fundamental vs. the absence of a fundamental.
Most of what a bass player gets isn't fundamental anyhow - with the usual "club" level stage set up... so, a whole lot depends on what "sound" or "voicing" a given artist is trying to get from his/her rig + guitar.
My 2 pesos worth...
_-_-bear
I think what may make it sound halfway good is the presence of a fundamental vs. the absence of a fundamental.
Most of what a bass player gets isn't fundamental anyhow - with the usual "club" level stage set up... so, a whole lot depends on what "sound" or "voicing" a given artist is trying to get from his/her rig + guitar.
My 2 pesos worth...
_-_-bear
Hi.
The very short answer to this question is a bass guitar cabinet needs high
efficiency, and therefore is very big related to its actual bass extension,
this renders PR's useless compared to normal ports, PR's are only useful
for small low efficiency designs with impractical port dimensions.
rgds, sreten.
The very short answer to this question is a bass guitar cabinet needs high
efficiency, and therefore is very big related to its actual bass extension,
this renders PR's useless compared to normal ports, PR's are only useful
for small low efficiency designs with impractical port dimensions.
rgds, sreten.
Ummmm... how do you figure that sreten?
Offhand I'd say that was incorrect.
Bass extension is very relative since a typical bass guitar doesn't really go that low to begin with... driver sensitivity for the same magnet and VC assembly will be lower for a lower Fs - which requires higher mass, and probably a change in the spider and maybe the surround, but I digress...
These days with kilowatt plus speakers and lightweight class D amps with similar ratings it seems silly to me to say that the traditional limitations all still apply in the case of a bass guitar rig...
And PRs work almost exactly as a port will in the case of "ideal" size cabinets... maybe better.
_-_-
Offhand I'd say that was incorrect.
Bass extension is very relative since a typical bass guitar doesn't really go that low to begin with... driver sensitivity for the same magnet and VC assembly will be lower for a lower Fs - which requires higher mass, and probably a change in the spider and maybe the surround, but I digress...
These days with kilowatt plus speakers and lightweight class D amps with similar ratings it seems silly to me to say that the traditional limitations all still apply in the case of a bass guitar rig...
And PRs work almost exactly as a port will in the case of "ideal" size cabinets... maybe better.
_-_-
Hi,
I do not know which part you are disagreeing with, PR's do not
exist for PA speakers and bass guitar cabinets because they are
simply not needed, ports are fine, cheaper and easier to implement.
Whist you can use Class D and subwoofer type drivers the drivers
are are not very good for the midrange, most musicians still prefer
things done the old fashioned way, good midrange output and
level is more important than the bass end when playing live.
Your right most bass cabs do not have bass ends designed like
hifi speakers, the bass end is sacrificed for high efficiency
and reasonable portability.
Just depends on what sort of amplifier and cabinet you want to use.
Best set up I've ever played through was a Fender Bassman amplifier
(130W) with a deep proper bass cabinet Trace Elliot 4 x 12 ", lovely
and a joy to play through towards is upper level limits, you control
the sound through your finger dynamics, something that will not
happen with kW class D amplifers and linear subwoofers.
Even more important if you use a plectrum, (I don't).
My bass amp which I like is old Peavy mkIII (130W/8 ohm and
with 8 2N3055 output transistors double that into 4ohms)
with a 4x10" cab sealed and a ported 15"cab, usually just
use the 15", adding the 4x10" is occasional.
rgds, sreten.
(I do not use any pedals or effect processing with my active bass.)
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Can I resurrect and oldish thread?
I'm approaching the same issue from the other side, I know what I want, would passive radiators help?
I am a cursed combination of a Hi-Fi fan, and a bass guitar player. I've built a lot of my own gear. I've been trying to build a bass amp and speaker that can reproduce the entire range of my bass guitar without low end roll-off, at about 110 DB. A sadist? Maybe 🙂. I want to make people feel the thunder at my will 🙂. Remember Sensurround? I never have forgiven Fender for ditching the fundamentals and just reproducing the harmonics. They still eschew a proper neck pickup location on most guitars, where the thunder is. At least Ampeg, Sunn, and later Peavey tried in their amplifiers, and Gibson in their basses.
My first attempt, 1970, playing through a HiFi preamp, a Fairchild 275 75 watt tube amp (a pair of 6550s), and a butt load of 15" Utah bass guitar speakers, didn't do it. Not loud or low enough.
Now, to make things worse, I'm playing a 5 string bass, low B is about 31 Hz, couldn't live without that low B. My current setup is a full stack, with a Hartke 250 watt amp driving 4 10"s, to deliver transient punch, and a Hartke 350 watt amp driving an EV 18" sub in a ported cab for the thunder. No crossover, doing that with the graphic equalizers on both amps.
It's OK for large indoor shows, not so much outdoors. And being 67 years old now, loading all this stuff into my van is not fun, especially at 1AM after a gig.
So now, given the availability of class D amps that challenge the power grid, and speaker technology that can handle stupid power levels, but maybe not deliver enough cone travel to move enough air at 31 Hz, with cone weights that may stifle transient response to deliver the punch, what is the best answer?
Marty
I'm approaching the same issue from the other side, I know what I want, would passive radiators help?
I am a cursed combination of a Hi-Fi fan, and a bass guitar player. I've built a lot of my own gear. I've been trying to build a bass amp and speaker that can reproduce the entire range of my bass guitar without low end roll-off, at about 110 DB. A sadist? Maybe 🙂. I want to make people feel the thunder at my will 🙂. Remember Sensurround? I never have forgiven Fender for ditching the fundamentals and just reproducing the harmonics. They still eschew a proper neck pickup location on most guitars, where the thunder is. At least Ampeg, Sunn, and later Peavey tried in their amplifiers, and Gibson in their basses.
My first attempt, 1970, playing through a HiFi preamp, a Fairchild 275 75 watt tube amp (a pair of 6550s), and a butt load of 15" Utah bass guitar speakers, didn't do it. Not loud or low enough.
Now, to make things worse, I'm playing a 5 string bass, low B is about 31 Hz, couldn't live without that low B. My current setup is a full stack, with a Hartke 250 watt amp driving 4 10"s, to deliver transient punch, and a Hartke 350 watt amp driving an EV 18" sub in a ported cab for the thunder. No crossover, doing that with the graphic equalizers on both amps.
It's OK for large indoor shows, not so much outdoors. And being 67 years old now, loading all this stuff into my van is not fun, especially at 1AM after a gig.
So now, given the availability of class D amps that challenge the power grid, and speaker technology that can handle stupid power levels, but maybe not deliver enough cone travel to move enough air at 31 Hz, with cone weights that may stifle transient response to deliver the punch, what is the best answer?
Marty
There is none.
For live audio you use typical High Efficiency drivers
So finding a driver is possible. To do around 30 Hz
But you cant beat physics 18" or 21" driver in a reflex/ported cabinet, will need
to be well over 7 to 10 cubic feet. To have a F3 of 30 Hz
actually feel lucky to get 40 Hz
Real answer is most players are using lighter cabinets
and high power neos usually 2x15 or very popular ( smaller) 2x12
Since watts are cheap and easy, and a 2x driver can realistically actually handle
the typical class D ice power bass amps of today. Around 500 to 800 watts
most guys are fine with a 2x12 or at extreme needs another matching 2x12
for 4x12
this happens a lot, bass players think they need 30 Hz cabs.
When open string on attack yes is 30 Hz but majority of the
note sustain is second harmonic and 3rd harmonic 60 and 100 Hz
that is the actual timber you hear.
that is open string low B any fretted note is higher in pitch
its why 50 to 65 Hz bass cabs work.
having done live sound in clubs where the mains had subs
that actually do 30 Hz. Bass players go absolutely nuts
if I put the signal to the sub. Again the little micro second
of fundamental when they first hit the note. Behaves entirely different
it blooms and sounds odd. And most have very little note control anyways.
or find out how important note control is, if you actually hear fundamental.
Actually not really hear, but a burst of pressure that you only feel.
then rolls into a bloom as the 2nd takes over.
So they tend to realize this when they actually hear a sub and hate it.
Not just one or 2 guys, many well experienced or average players
freak out if the bass is in the sub.
Takes a 3rd or 4th order filter which can be set to anywhere
from 40 up to 55 Hz before they stop whining about the sub.
For live audio you use typical High Efficiency drivers
So finding a driver is possible. To do around 30 Hz
But you cant beat physics 18" or 21" driver in a reflex/ported cabinet, will need
to be well over 7 to 10 cubic feet. To have a F3 of 30 Hz
actually feel lucky to get 40 Hz
Real answer is most players are using lighter cabinets
and high power neos usually 2x15 or very popular ( smaller) 2x12
Since watts are cheap and easy, and a 2x driver can realistically actually handle
the typical class D ice power bass amps of today. Around 500 to 800 watts
most guys are fine with a 2x12 or at extreme needs another matching 2x12
for 4x12
this happens a lot, bass players think they need 30 Hz cabs.
When open string on attack yes is 30 Hz but majority of the
note sustain is second harmonic and 3rd harmonic 60 and 100 Hz
that is the actual timber you hear.
that is open string low B any fretted note is higher in pitch
its why 50 to 65 Hz bass cabs work.
having done live sound in clubs where the mains had subs
that actually do 30 Hz. Bass players go absolutely nuts
if I put the signal to the sub. Again the little micro second
of fundamental when they first hit the note. Behaves entirely different
it blooms and sounds odd. And most have very little note control anyways.
or find out how important note control is, if you actually hear fundamental.
Actually not really hear, but a burst of pressure that you only feel.
then rolls into a bloom as the 2nd takes over.
So they tend to realize this when they actually hear a sub and hate it.
Not just one or 2 guys, many well experienced or average players
freak out if the bass is in the sub.
Takes a 3rd or 4th order filter which can be set to anywhere
from 40 up to 55 Hz before they stop whining about the sub.
I've seen spectrograms showing the 4th harmonic as the strongest frequency component from a bass guitar. All the way up at 123.5 Hz from a 30.87 Hz low B string!
It's not just about the position of the neck pickup on the bass guitar; it's also about the position at which the string is picked. I've never seen any bassist pluck/pick the open strings over the 12th fret, which is where you need to pick if the goal is to encourage lots of output at the fundamental frequency of the string. This would be a very bizarre way to play the bass, as you'd have to position your picking/plucking hand halfway down the neck, crossed across your body!
The type of guitar strings used matters, as well. The La Bella HRS strings on one of my 5-string basses are particularly interesting: the low B string has non-uniform thickness, and a "step" in thickness where the outermost wire wrap deliberately ends. This deliberate non-uniformity encourages "growl", i.e. higher fundamental frequencies. In other words, the fundamental frequency is deliberately made weaker.
I'm not much of a bassist, but I do play bass guitar at home for fun, and also on my own home recordings. I have both 5-string and 4-string basses. I find my 5-string bass parts sound better, and sit better in the mix, if I high pass the (direct injected, DI) bass signal at around 60 - 70 Hz.
IME, frequencies below that just add sonic mud, taking away clarity and muddying the sound of the track.
Interesting! That pretty much matches my own experience, as described above.
-Gnobuddy
Or.... any speaker that fits in the Econoline/Transit muds-up at HIGH level and low frequency. (Excursion is NOT the answer, it is the problem. Use a bigger paddle!)
I too love deep bass but nobody can pay me to haul huge boxes around.