Hi I'm designing a box with 2 Dayton RS150T-8 (40W each) in parallel combined with a passive radiator. (and a tweeter but not important here 🙂)
What I'm now seeing is that at (very) low input (10v) 25W the basta simulation excursion graph show that I'm at Xmax ? Actually much earlier if I take the frequencies lower than 44 Hz into account.
Anybody willing to explain this please ? (I can reduce the box Vb but then the charterictics are way off) ps, vent / passive radiator are exact as per vendors parameters. (SB15SFCR-00)
Thx !
What I'm now seeing is that at (very) low input (10v) 25W the basta simulation excursion graph show that I'm at Xmax ? Actually much earlier if I take the frequencies lower than 44 Hz into account.
Anybody willing to explain this please ? (I can reduce the box Vb but then the charterictics are way off) ps, vent / passive radiator are exact as per vendors parameters. (SB15SFCR-00)
Thx !
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Below tuning frequency the cone unloads and flaps about like a dying fish. You can either hope most recordings don't have loud sub 30Hz signals, or use a high pass filter.(maybe your modelling program can show response with a HPF in place)
At normal 'home' levels you might be ok without a filter.
Rob.
At normal 'home' levels you might be ok without a filter.
Rob.
Funny 🙂 True much better with the HP filter in the simulation and yes it is a home set-up so I cannot (will not) put an active HP filter or passive for that matter in the crossover for those low freqs.
Is that done sometime in passive filters (for home use) ? ( I have not seen it)
Thx
Is that done sometime in passive filters (for home use) ? ( I have not seen it)
Thx
I don't recall seeing passive high pass filters for subs.(cost of components would be quite high I think) I've seen some pro amps with a switch on the back, and I ~think~ I remember some plate amps with built in, un-defeatable high pass filters.
Cheers,
Rob.
Cheers,
Rob.
Are you using a DIY amp?
You could change the input coupling capacitor to limit low bass response a little although it won´t be a steep filter.
Another alternative would be an external passive line level crossover where you could make the filter steeper.
You could change the input coupling capacitor to limit low bass response a little although it won´t be a steep filter.
Another alternative would be an external passive line level crossover where you could make the filter steeper.
A problem with ported designs. No load on speaker at low Hz.
I have always used sealed cabinets and then hammered my speakers to within an inch of their life on a mobile disco.
Never had a speaker blow yet.
I have always used sealed cabinets and then hammered my speakers to within an inch of their life on a mobile disco.
Never had a speaker blow yet.
25 "watts" should require around 14 "volts", but of course depends on what the impedance is at any given frequency..
Not at all unusual for a woofer to exceed Xmax in a large box with an Fb well below Fs at less than half of it’s thermal power handling capacity rated in watts (Pe).
Xmax should be the limit of linear excursion, past which distortion rises rapidly.
Pe is a survivability, not distortion rating.
Exceeding Xmax should not cause damage, exceeding Xlim/ Xmech will.
Xlim is a hard mechanical limit, either from suspension surround or spider(s) being fully extended, or voice coil former hitting the back plate.
If the voice coil former hits the back plate hard and fast, it may be damaged instantly. If you push the cone by hand and hear a “click” before the suspension is fully extended, both a HPF and voltage limiting are required to protect the driver.
Fortunately, most current woofer’s Xlim is about double Xmax, and usually is suspension limited. Most driver’s Bl (motor strength) has reduced at that excursion enough that the driver won’t be instantly mechanically damaged if within it’s power limits. If driven to Xlim, the suspension will make more of a “buh” or “puh” sound, rather than the “click” of a voice coil former.
Given enough voltage, when pushed to Xlim, the cone may kink or shred, or other “soft parts” may rip.
Passive radiators are only limited by their suspension, their Xmax is the same as a loudspeaker’s Xlim, so they will make similar bad noises at Xmax as a loudspeaker at Xlim.
Art
Basta helps you out here also. Tuning the vent/PR to about 0,7 times lower and applying an active highpass with Q=1,93 (you only have to establish the R and C values around the opamp circuit shown in the app) gives you useful subsonic protection and some low end extension. This B6-technique is quite old but still effective and cheap. And brings you your desired extension in a smaller enclosure.
With normal tuning (around 50Hz with the average 5") and ditto listening, you won't damage these units that easily. My 2ct: don't try to push them too low.
With normal tuning (around 50Hz with the average 5") and ditto listening, you won't damage these units that easily. My 2ct: don't try to push them too low.
It is much cheaper rolling off 12 db/octave or better at 40 hz in the line level stage instead of in the speaker crossover.
Mixers like PV8 have switchable subsonic filter, 80 hz. Stage mikes pick up footfalls on the stage if the mike has low response. I bought my PV8 for $39 off ebay and replaced the volume pot for $8. Since my RCA out preamp was 12' from the power amp, I had hum using coax cables. Inserting the PV8 in the chain at the head end, and driving twisted pair phone jack cable, the noise was reduced. Nice low hiss 4565 op amps in the PV8. 4558 op amps in some products are not so nice, at higher gains.
Another brand of mixer is Alesis. Old 90's Mackies are reputedly good, new ones are reputedly not.
Electronic crossovers also have subsonic filters. I picked up a Nady 225CT for $50. It's main function is to filter off bass from two line level channels for a sub channel, with a selectable crossover point from 60 to 400 hz. But there is also a low filter switch. My Peavey SP2 (2004) speakers roll off 10 db below 54 hz. As I listen to organ records, I might want an 18" sub someday. The crossover came at that price with the SP2's (for $200 each). Even listening to organ LP's, below 25 hz is noise and not to be sent to a speaker.
Mixers like PV8 have switchable subsonic filter, 80 hz. Stage mikes pick up footfalls on the stage if the mike has low response. I bought my PV8 for $39 off ebay and replaced the volume pot for $8. Since my RCA out preamp was 12' from the power amp, I had hum using coax cables. Inserting the PV8 in the chain at the head end, and driving twisted pair phone jack cable, the noise was reduced. Nice low hiss 4565 op amps in the PV8. 4558 op amps in some products are not so nice, at higher gains.
Another brand of mixer is Alesis. Old 90's Mackies are reputedly good, new ones are reputedly not.
Electronic crossovers also have subsonic filters. I picked up a Nady 225CT for $50. It's main function is to filter off bass from two line level channels for a sub channel, with a selectable crossover point from 60 to 400 hz. But there is also a low filter switch. My Peavey SP2 (2004) speakers roll off 10 db below 54 hz. As I listen to organ records, I might want an 18" sub someday. The crossover came at that price with the SP2's (for $200 each). Even listening to organ LP's, below 25 hz is noise and not to be sent to a speaker.
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You are listening with your eyes and needlessly worrying, you have actually designed a very good little system.
As mentioned above, a proper hi pass circuit will bring much needed peace of mind.
Not sure why you reject that beforehand,it´s quick and simple.
You might even build it inside your power amp, so as to save on case and supply.
As mentioned above, a proper hi pass circuit will bring much needed peace of mind.
Not sure why you reject that beforehand,it´s quick and simple.
You might even build it inside your power amp, so as to save on case and supply.
Thank you all great feedback ! , as for the hi pass circuit, I'll determine when it is build and how it plays. It is "only" for home (Jazz mostly) use. A bit funny I have been building DIY amps for years and have always been aiming to get from 20 Hz to 20 KHz and now I'm going to limit it 🙂 , Cheers , stay safe.
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For anything but some organ works, some electronic music and a very few piano pieces the lowest frequency you are most likely to encounter is the open E string of the electric bass at 42Hz.
(5 string basses are common with a lower A string but are mostly used so the low E can be fretted since played open it sounds quite different)
(5 string basses are common with a lower A string but are mostly used so the low E can be fretted since played open it sounds quite different)
And it's also very uncommon for those low frequencies to be even within 10dB of what's happening further up the band.
The low "A" on a grand piano is 27.5Hz, the low "B" on a 5 string bass is 31Hz.
Though LF fundamentals may be -10dB (or less) in most acoustic recordings, note that the OP's simulation response has dropped to -10dB at 30Hz, and has reached Xmax for both the driver and passive radiator at 95dB.
Due to our hearing being less sensitive to low frequencies ("equal loudness level contour"), an SPL of 95dB at 30Hz sounds about the same level as 52dB at 1000Hz, about half as loud as an average conversational level at one meter.
Art
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True.
It´s also true that thanks God BOTH have a ton of harmonics (Bass strings are normally roundwound, much like a Piano string) , or in either case they would "disappear".
Normal is our brain "reconstructing" the Fundamental from its harmonics (which are WAY easier to play and hear) with very little fundamental remaining, if t all.
Notice the "roundwound", "bright" and "hard hitting tone" labels printed on the sleeve.
one string from that set:
It´s also true that thanks God BOTH have a ton of harmonics (Bass strings are normally roundwound, much like a Piano string) , or in either case they would "disappear".
Normal is our brain "reconstructing" the Fundamental from its harmonics (which are WAY easier to play and hear) with very little fundamental remaining, if t all.
Notice the "roundwound", "bright" and "hard hitting tone" labels printed on the sleeve.
one string from that set:
I've got one of the first pianos to successfully fake out 27 hz with wirewound 50" strings in a 40" tall case. A 1940 Steinway console. Before that real 27 hz came in 600 lb uprights, or 800 lb grands. By 1950 every piano manufacturer was copying it in the top 40" models.
Note to OP. I've had the woofers in my SP2-XT move 3/4 inch when I walked across the wood floor with the phono channel on and the arm down on the record. Xmax of the 1505-8kadt is .9 mm . Volume was set to 1/8 to 35 watt depending on source volume. No damage. The low cut on my RA-88a disco mixer was annoying and only 6 db/octave.
Note to OP. I've had the woofers in my SP2-XT move 3/4 inch when I walked across the wood floor with the phono channel on and the arm down on the record. Xmax of the 1505-8kadt is .9 mm . Volume was set to 1/8 to 35 watt depending on source volume. No damage. The low cut on my RA-88a disco mixer was annoying and only 6 db/octave.
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Point is he is unlikely to encounter them.
from wiki:
"The extra keys are added primarily for increased resonance from the associated strings; that is, they vibrate sympathetically with other strings whenever the damper pedal is depressed and thus give a fuller tone. Only a very small number of works composed for piano actually use these notes. "
AND when 5 string Bass Guitars are used, you don´t much hear the harmonics and practically zero fundamentals BUT they bare always "present".
How?
Quite nonlinear Tube Bass amps played LOUD make the lowest frequencies modulate the others, intermodulate actually, and that is very apparent.
I had to artificially add that to my own SS Bass amps, with great success.
Best players in Argentina have SOLD their Ampeg SVT to buy mine, go figure.
Here´s an example of 5 string Bass Guitar solo:
5 STRINGS BASS SOLO - YouTube
pay attention to the 5th string left to decay on its own the end, around 2:15
another from a very well known Bass Player (of Megadeth fame):
https://youtu.be/bCjOiWXsW8U?t=80
in all cases , harmonic rich "piano type" sound helps brain reconstruct the note being played.
How?
Quite nonlinear Tube Bass amps played LOUD make the lowest frequencies modulate the others, intermodulate actually, and that is very apparent.
I had to artificially add that to my own SS Bass amps, with great success.
Best players in Argentina have SOLD their Ampeg SVT to buy mine, go figure.
Here´s an example of 5 string Bass Guitar solo:
5 STRINGS BASS SOLO - YouTube
pay attention to the 5th string left to decay on its own the end, around 2:15
another from a very well known Bass Player (of Megadeth fame):
https://youtu.be/bCjOiWXsW8U?t=80
in all cases , harmonic rich "piano type" sound helps brain reconstruct the note being played.