Hi All,
I've done a lot of searching here, and I can't seem to find much on diy subs that compete with , for example, the paradigm servo 15 or the velodyne hgs-18 type stuff. I believe you'd need 2 servo 15's to match a hgs 18 however.
In my room i've got enough space behind the screen for 4 labhorns. However, I'm not sure if even that would compare to the depth ( 10Hz-20Hz) that servo subs would drop to.
I've looked at a few distortion figures of, for example the shivas, and they quote 3% whilst the servos are 0.3
Lets say my budget is around £800 uk(for drivers) and I can stretch to a second hand pa amp for the power. Are there any multiple vented 18's, bandpass, passive radiator type solutions that will give these subs a run for their money ? ie : 15 Hz @ 105ish Db
I tried to find info on the diy contrabass (contrabass corner) but it's disappeared..
This is purely for the .1 channel in DD/DTS btw - no bass re-direction.Room is 20' x 11'.
Any info much apreciated
Thanks
Rob
I've done a lot of searching here, and I can't seem to find much on diy subs that compete with , for example, the paradigm servo 15 or the velodyne hgs-18 type stuff. I believe you'd need 2 servo 15's to match a hgs 18 however.
In my room i've got enough space behind the screen for 4 labhorns. However, I'm not sure if even that would compare to the depth ( 10Hz-20Hz) that servo subs would drop to.
I've looked at a few distortion figures of, for example the shivas, and they quote 3% whilst the servos are 0.3
Lets say my budget is around £800 uk(for drivers) and I can stretch to a second hand pa amp for the power. Are there any multiple vented 18's, bandpass, passive radiator type solutions that will give these subs a run for their money ? ie : 15 Hz @ 105ish Db
I tried to find info on the diy contrabass (contrabass corner) but it's disappeared..
This is purely for the .1 channel in DD/DTS btw - no bass re-direction.Room is 20' x 11'.
Any info much apreciated
Thanks
Rob
By servo subs, I gather you mean these subs have a type of motion feedback? Well, you could always implement such a system yourself. In theory it would decrease distortion, although I've never measured. It is cool to see your sub driver stay still when it's on and you tap it.
The shiva isn't the driver with the lowest distortion in it's price range. I do believe on linkwitz's site the peerless XLS had the lowest distortion of those he tried. But then you could always go up a price notch and I remember seeing graphs that showed the DPL12 in a good light. Even there, there are more lower distortion units out there.
The shiva isn't the driver with the lowest distortion in it's price range. I do believe on linkwitz's site the peerless XLS had the lowest distortion of those he tried. But then you could always go up a price notch and I remember seeing graphs that showed the DPL12 in a good light. Even there, there are more lower distortion units out there.
Hi Rob,
Have you look at the Tumult from Adire Audio
http://www.adireaudio.com/diy_audio/drivers/adire/tumult.htm
They claim 5 litres of linear displacement at 89-W-m, and will take 1600W of power. I heard this woofer at the CES. It was impressive.
Have you look at the Tumult from Adire Audio
http://www.adireaudio.com/diy_audio/drivers/adire/tumult.htm
They claim 5 litres of linear displacement at 89-W-m, and will take 1600W of power. I heard this woofer at the CES. It was impressive.
Attachments
Servo Sub
To create a servo sub you will need the following:
1. Linear Motor (Loudspeaker)
2. LVDT Linear Variable Disfferential Transformer
3. LVT Linear Velocity Transducr
4. Power Amp good down to DC
5. Two servo loops
The LVT and LVDT must be connected directly to the moving mass.
The input from your preamp, and the two servo loops get summed and feed the amplifier.
Each Servo loop is basicly a difference amp with gain.
The LVDT uses a syncronus demodulator to determine the position of the cone.
Run the LVDT at the highest frequency you can get away with ~20Khz.
The LVT determines the actual velocity of the cone.
To do this you will need a VERY RUGGED speaker with a vent in the pole piece. The LVT and LVDT shpuld be attached via a shft to the moving assembly.
To build your LVT you only need a magnet inside a coil, the magnet is attached to the shaft and the coil is stationary.
The LVDT and LVT need to have coils that are longer than the travel of the voice coil.
A souce for the LVDT is Digikey. Search for LVDT
For an LVDT with +/- 0.5" travel expect to pay ~100.00.
Its been 18 years since I designed linear motors but they are not terribly difficult.
The key is to have an impecable mechanical connection and some protecttion to not damage the moving mass should a disconection occur. The thing will keep dumping current into the voice coil until the position is satisfied.
To create a servo sub you will need the following:
1. Linear Motor (Loudspeaker)
2. LVDT Linear Variable Disfferential Transformer
3. LVT Linear Velocity Transducr
4. Power Amp good down to DC
5. Two servo loops
The LVT and LVDT must be connected directly to the moving mass.
The input from your preamp, and the two servo loops get summed and feed the amplifier.
Each Servo loop is basicly a difference amp with gain.
The LVDT uses a syncronus demodulator to determine the position of the cone.
Run the LVDT at the highest frequency you can get away with ~20Khz.
The LVT determines the actual velocity of the cone.
To do this you will need a VERY RUGGED speaker with a vent in the pole piece. The LVT and LVDT shpuld be attached via a shft to the moving assembly.
To build your LVT you only need a magnet inside a coil, the magnet is attached to the shaft and the coil is stationary.
The LVDT and LVT need to have coils that are longer than the travel of the voice coil.
A souce for the LVDT is Digikey. Search for LVDT
For an LVDT with +/- 0.5" travel expect to pay ~100.00.
Its been 18 years since I designed linear motors but they are not terribly difficult.
The key is to have an impecable mechanical connection and some protecttion to not damage the moving mass should a disconection occur. The thing will keep dumping current into the voice coil until the position is satisfied.
More Servo Info
To prevent damage to the coil as a last ditch place a fuse in series with the coil.
To eliminate driving the coil beyond where it is supposed to go a limiter.
To prevent rumble, especially if you have a turntable a high pass filter.
The best enclosue would likely be a dipole for this setup with the spakers cone pointing downward. The output from the front of the cone feeds toward the listener and the output from the rear of the cone is feeding away from the listener.
I hope I haven't discouraged you yet.
To prevent damage to the coil as a last ditch place a fuse in series with the coil.
To eliminate driving the coil beyond where it is supposed to go a limiter.
To prevent rumble, especially if you have a turntable a high pass filter.
The best enclosue would likely be a dipole for this setup with the spakers cone pointing downward. The output from the front of the cone feeds toward the listener and the output from the rear of the cone is feeding away from the listener.
I hope I haven't discouraged you yet.
If you go that far for building your own MFB sub as you suggested in your older post then you can as well do the things above with more modern approaches:
Instead of using a fuse (definitely a no-no in space-age !!), use a limiter that limits average power, fed to the woofer. Or use a woofer that can withstand the power. But definitely take care that you don't run your amp into clipping.
The 2nd and 3rd problem can be solved at once with a voltage-controlled filter (control signal derived from your sensor in this case).
Regards
Charles
Hi everyone - wow quite a few replies
I made a mistake on the 3% distortion quote - it was from the Tumult's specs.
Ok from the top :
sfdoddsy (Steve) - I hope your right there - it's hard to find any like for like distortion measurements to make a reasonable comparison.
Joebob, MIKET
I don't feel qualified to delve into diy servo's. I'm having enough nerves getting ready to make an active x/o However thanks for putting the suggestion in. Maybe when I've more experience...
This is why I asked about the more "off the shelf" type enclosures.
roddyama,
I've spent a few months searching through all the usual suspects,. The Tumult is quite pricey in the UK(£560 ), but would be a fun project. Maybe a single first, adding second box later.
phase_accurate
By ELF I'm assuming you mean an electronically boosted low end with sealed drivers. (Linkwitz transform type stuff?) I'd need a hell of a lot of displacement with no ports. Ignoring room gain I'd need 2L displacement for 105 Db @ a 15Hz Also I'd need good quality drivers to keep distortion low.
I should mention that I'm using 4 10" scanspeak drivers (sealed) in my left/right speaks, and feel theres enough bass for music but not enough for dvd's.(approx 1L total displacement)
The other option is to build a pair of labhorns, and assist the 10-20Hz range with an ELF or possibly bandpass design. - best of both worlds ?
Romy - the Paradigm servo15 I heard produced a hell of a lot of low bass (and pretty clean to my ears too). Your saying that a QSC pro amp rated at , say 1000W into 4 ohms is unable to drive a subwoofer ? Please can you elaborate for me..
Thanks to all,
Rob
I made a mistake on the 3% distortion quote - it was from the Tumult's specs.
Ok from the top :
sfdoddsy (Steve) - I hope your right there - it's hard to find any like for like distortion measurements to make a reasonable comparison.
Joebob, MIKET
I don't feel qualified to delve into diy servo's. I'm having enough nerves getting ready to make an active x/o
However thanks for putting the suggestion in. Maybe when I've more experience...This is why I asked about the more "off the shelf" type enclosures.
roddyama,
I've spent a few months searching through all the usual suspects,. The Tumult is quite pricey in the UK(£560
), but would be a fun project. Maybe a single first, adding second box later.phase_accurate
By ELF I'm assuming you mean an electronically boosted low end with sealed drivers. (Linkwitz transform type stuff?) I'd need a hell of a lot of displacement with no ports. Ignoring room gain I'd need 2L displacement for 105 Db @ a 15Hz Also I'd need good quality drivers to keep distortion low.
I should mention that I'm using 4 10" scanspeak drivers (sealed) in my left/right speaks, and feel theres enough bass for music but not enough for dvd's.(approx 1L total displacement)
The other option is to build a pair of labhorns, and assist the 10-20Hz range with an ELF or possibly bandpass design. - best of both worlds ?
Romy - the Paradigm servo15 I heard produced a hell of a lot of low bass (and pretty clean to my ears too). Your saying that a QSC pro amp rated at , say 1000W into 4 ohms is unable to drive a subwoofer ? Please can you elaborate for me..
Thanks to all,
Rob
Hi,
SPL is proportional to acceleration of the cone. So you need an acceleration transducer mounted on a suitable place on the speaker cone. Piezo elements are excellent acc. transducers. Good and cheap ones can be found in piezo tweeters like the Motorola’s.
Have experimented long time ago with these piezo’s mounted behind the dust cap of a Visaton GF200 woofer in a 25L box. It is not so easy to get such a system stable at higher frequencies. It is quite easy to build a power oscillator this way. Finally it sounded pretty well. But I found it not much better than a woofer corrected with a Linkwitz transform.
Cheers
SPL is proportional to acceleration of the cone. So you need an acceleration transducer mounted on a suitable place on the speaker cone. Piezo elements are excellent acc. transducers. Good and cheap ones can be found in piezo tweeters like the Motorola’s.
Have experimented long time ago with these piezo’s mounted behind the dust cap of a Visaton GF200 woofer in a 25L box. It is not so easy to get such a system stable at higher frequencies. It is quite easy to build a power oscillator this way. Finally it sounded pretty well. But I found it not much better than a woofer corrected with a Linkwitz transform.
Cheers
*** Romy - the Paradigm servo15 I heard produced a hell of a lot of low bass (and pretty clean to my ears too).
The question is not about the “hell of a lot of low bass” but about the specific properly of the bass stricture, its ability to maintain a certain attack/decay patters at the different volume levels, its ability to move with the certain acceleration throughout it’s dynamic range and many- many others. I would not really be able to explain it hear because the most of the DIY people do not have are serious listening objectives (look at the local musical forum and you won’t have any questions) that would permit them to evaluate the subjective results and to bind the results with a prospective engendering decisions. All that I would say is that I have heard practically ALL servo-based systems: I did not hear any serious bass there but just the LF nose.
*** Your saying that a QSC pro amp rated at , say 1000W into 4 ohms is unable to drive a subwoofer ?
All that this amp will do will be just producing a sufficient excursion of the LF driver but it has no relation to Sound.
Rgs,
The Cat
The question is not about the “hell of a lot of low bass” but about the specific properly of the bass stricture, its ability to maintain a certain attack/decay patters at the different volume levels, its ability to move with the certain acceleration throughout it’s dynamic range and many- many others. I would not really be able to explain it hear because the most of the DIY people do not have are serious listening objectives (look at the local musical forum and you won’t have any questions) that would permit them to evaluate the subjective results and to bind the results with a prospective engendering decisions. All that I would say is that I have heard practically ALL servo-based systems: I did not hear any serious bass there but just the LF nose.
*** Your saying that a QSC pro amp rated at , say 1000W into 4 ohms is unable to drive a subwoofer ?
All that this amp will do will be just producing a sufficient excursion of the LF driver but it has no relation to Sound.
Rgs,
The Cat
Romy,
Could you try and be a little more ambiguous? I think I'm close to getting your point.
Anyway...
The servo-sub I heard sounding extremely clean and low. It was almost too clean. The transient impact was not there.
If you have the room, I think that an array of drivers is capable of producing strong, clean, bass that is comparable to a servo. It will not be quite as clean, but the transient ability will be better, in my opinion. Even using 8 cheap 8" drivers, my setup is fairly impressive, and definitely shows the potential for such a system with better quality drivers. A likwitz transform can work well in this type of situation to get the extension.
Could you try and be a little more ambiguous? I think I'm close to getting your point.
Anyway...
The servo-sub I heard sounding extremely clean and low. It was almost too clean. The transient impact was not there.
If you have the room, I think that an array of drivers is capable of producing strong, clean, bass that is comparable to a servo. It will not be quite as clean, but the transient ability will be better, in my opinion. Even using 8 cheap 8" drivers, my setup is fairly impressive, and definitely shows the potential for such a system with better quality drivers. A likwitz transform can work well in this type of situation to get the extension.
Thanks for more input, Pjotr.
Hi Steve - I reckon multiple drivers will help push towards the servos' lower distortion. Also I think that when you say that servos are too clean you are right, but this is how I like bass.
Romy, you've basically said that all the 'standard' types of sub are useless, and told me to look elsewhere. Where exactly? I'm having trouble understanding your arguments, and don't know if it's your spelling or your disdain for the diy community. Quotes like "I would not really be able to explain it hear because the most of the DIY people do not have are serious listening objectives " are not exactly helpful, and almost unintelligible too. If you feel that you're above these types of speakers fair enough, just ignore my posts.
Cheers
Rob
Hi Steve - I reckon multiple drivers will help push towards the servos' lower distortion. Also I think that when you say that servos are too clean you are right, but this is how I like bass.
Romy, you've basically said that all the 'standard' types of sub are useless, and told me to look elsewhere. Where exactly? I'm having trouble understanding your arguments, and don't know if it's your spelling or your disdain for the diy community. Quotes like "I would not really be able to explain it hear because the most of the DIY people do not have are serious listening objectives " are not exactly helpful, and almost unintelligible too. If you feel that you're above these types of speakers fair enough, just ignore my posts.
Cheers
Rob
OK Rob,
You have probably looked at these as well, but here's the VMPS subs
http://www.vmpsaudio.com/sub1.htm
5% distortion at 115db down to 17Hz. A little mass on the PR maybe???.
$329USD for the kit wo/cabinet
You have probably looked at these as well, but here's the VMPS subs
http://www.vmpsaudio.com/sub1.htm
5% distortion at 115db down to 17Hz. A little mass on the PR maybe???.
$329USD for the kit wo/cabinet
Attachments
Yes, you understood me very correctly. I do confirm that an absent of the civilized listening objectives prevent many of people who do audio (DIYers and not) to achieve more noble results than to entertain the funny listeners with pterodactyls demands. If you insist me to ignore your post I will be happy to do so but not because I feel that I “above these types of speakers” but because I do not feel that you might generate a context worth the Cat’s attention.RobWells said:
Rgs,
Romy the Cat
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