# Anybody know about these? Velodyne subs and servos?



## Swanson's Performance (Mar 27, 2011)

VELODYNE DF12SC 12" CAR SUBWOOFERS JL IDQ DIAMOND MTX | eBay


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## dualmono21 (Oct 3, 2009)

i have a couple of them 
what would you like to know about them ?


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## Swanson's Performance (Mar 27, 2011)

Specs and such would be a great start.


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## dualmono21 (Oct 3, 2009)

In short ... They are difficult to set up , difficult to use and difficult to partner with other equipment 
But if you quite simply have to have the best sq car audio subwoofer ever made 
Then this is the one to buy 

They don't require huge power , but the box size is larger than average 
The servo control corrects the inherrant distortion created by allmost every subwoofer 
By taking a referance signal and comparing it with the output being produced 
It compares them some 2000 times a second then corrects the input to remove the distortion


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## Mike_Dee (Mar 26, 2011)

Some of the finest car audio subwoofers ever made.


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## thehatedguy (May 4, 2007)

They are great, but don't expect a lot of SPL.

The controller is picky about amps too. You will need an amp that is flat down to 5 hertz for it really to be happy.

I have the owners and installation manual at home from when I had my pair of 10s.

Truth be told, you could get as good of distortion performance from a lot of modern subs today. Back in the 90s not so much attention was paid to distortion in subwoofers, especially car marketed subwoofers.

But they are pretty sweet to have if you can afford them.


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## dualmono21 (Oct 3, 2009)

much as i agree with parts of your statement modern woofers still arent anywhere near to the distortion levels of a velodyne with the servo correction 

an "average woofer" such as the morel ultimo still has over 10% distortion 
a velodyne has less than 1% after the servo 

the velodyne has been the best automotive sq woofer for a long long time now 
and until a company or individual decides to go down the same route and try servo correction again then it might just well be the best EVER 

velodyne are no longer interested in the car audio market as they actaully lost money on the df10 and df12 
i do however have the schematics for the controller and accelorometers and would love to adapt this to a more modern woofer


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## theeaudioboy (Jun 3, 2011)

Swanson's Performance said:


> VELODYNE DF12SC 12" CAR SUBWOOFERS JL IDQ DIAMOND MTX | eBay


 
ya i gotting a pair of 15" velodyne subs back in 96' from a friends older brother he was in the home audio bussiness end and was really into SQ ! they retailed then for about $1200 each ! they were some of the finest quality subs out then ! and still are good ! but there are many now just as good ! and for half the cost ! but you also would defently have to use a good SQ amp to run them ! like infinity, diamond, audison, eclipse, zapco, clarion to name a few ! but in my opinion that price is a bit high even if they were brand new in the boxes !!! but still are good subs for SQ !


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## Swanson's Performance (Mar 27, 2011)

dualmono21 said:


> an "average woofer" such as the morel ultimo still has over 10% distortion
> a velodyne has less than 1% after the servo


Where exactly are you getting these numbers? I mean, I'd love to believe you, and I know Velodyne's servos are good. No offense, but anybody with a keyboard can create numbers. Do you have any published tests to document either of these claims? 

With that said, if servo technology was so much better than the average magnet, why was Velodyne the only company to experiment with it? But even more importantly, has it even been established that the average, untrained, uncritical ear can tell the difference between a very good sub such as the Ultimo and the Velodyne when their output levels are matched? Meaning, if both are powered to produce a 110dB SPL, with a blind survey, can Joe Blow tell he's listening to a $2,000 sub vs. a $400 one?

Thanks for the history though- didn't Velodyne make some 18" subs as well?


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## thehatedguy (May 4, 2007)

Nath (I think dualmono21 is Nath from Talk Audio), when the surround on one of my 10s went, I robbed the servos from it and still have the controller...I too have been wanting to impliment it on another sub.


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## thehatedguy (May 4, 2007)

For the home, the do 8-18s. For the car they only did 10s and 12s...there were like 6 15s for the car market produced.

Other people do/did servos, just not the way Velo did them. Kenwood and Linear Power both had servo feedback loops in their amps. They sensed a second voice coil and referenced that to the signal for correction.




Swanson's Performance said:


> Where exactly are you getting these numbers? I mean, I'd love to believe you, and I know Velodyne's servos are good. No offense, but anybody with a keyboard can create numbers. Do you have any published tests to document either of these claims?
> 
> With that said, if servo technology was so much better than the average magnet, why was Velodyne the only company to experiment with it? But even more importantly, has it even been established that the average, untrained, uncritical ear can tell the difference between a very good sub such as the Ultimo and the Velodyne when their output levels are matched? Meaning, if both are powered to produce a 110dB SPL, with a blind survey, can Joe Blow tell he's listening to a $2,000 sub vs. a $400 one?
> 
> Thanks for the history though- didn't Velodyne make some 18" subs as well?


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## dualmono21 (Oct 3, 2009)

Yes I am nath from the talk audio forum some of you guys will also know me from judging iasca competitions a few years ago 

And I've been using velodyne woofers since 1991 
Velodyne are not the only company to manufacture a servo control other companies have done so 
But most other companies only produce the controller not the sub itself 

A test on the velodyne df 12 was done in car stereo and security magazine I have a copy of the magazine and the results 
Which basically states the amount of distortion created by the velodyne was bordering on undetectable when the servo was connected , without it it registered around 18 per cent which for the time was also very good 
Nowadays good woofers are capable of getting very close to 10 per cent


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## dualmono21 (Oct 3, 2009)

the velodyne test was performed in the jan-feb issue of car stereo and security (no63) for anyone wishing to check it 

the speaker itself is conventional the same as many but not all manufacturers 
it uses a voice coil and a magnet 
it was the servo control which made it differant to other manufacturers

i have a spare controller but dont have any accelorometers id like to try this on a 15" aliante subwoofer i have to see if its possible to calibrate the sub with the controller 
if so ive a feeling it also could be pretty special


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## robert_wrath (Apr 24, 2011)

dualmono21 said:


> it was the servo control which made it differant to other manufacturers


This is the Key selling point of the package. The Servo Controller time corrected itself & guaranteed a 20 Hz cycle hit (provided enclose is built to spec).


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## dualmono21 (Oct 3, 2009)

It doesnt automatically correct for time but it does automatically correct for phase alignment 
Compared to the original signal , this is then adjustable to align the driver with the rest of the system 
The frequency response for the 12 in the reccomended size sealed enclosure is rated flat down to 13hz


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## bobduch (Jul 22, 2005)

FYI here is the install manual.


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## Swanson's Performance (Mar 27, 2011)

Nothing came through?


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## bobduch (Jul 22, 2005)

There now.


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## bobduch (Jul 22, 2005)

And the Velo has two servos. One on the signal and one for vehicle motion.


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## thehatedguy (May 4, 2007)

I just wonder if the servo controller would freak out being retro fitted to a modern higher excursion sub?


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## danno14 (Sep 1, 2009)

Swanson's Performance said:


> didn't Velodyne make some 18" subs as well?


At least for home.... my ULD18II is an example.
Not terribly large comparitively, but great extension and very, very clean.


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## roduk (Sep 19, 2008)

To all Velodyne owners - I have a DF10 and have used it for a couple of years now. I had a Soundstream Class A 10.2 Modified to play flat down as low as it can go by Gordon @ Genesis, it now sings after having all the LPF xovers removed and the power supply boosted up etc.. I am rebuilding the sub box atm and am wondering what effect it would have on the sub if it was smaller than recommended? 0.6-7 cubic feet as opposed to the recommended 1-1.5 cubic feet? I feel as if I'm getting a bit of a one note wonder atm - would this be a known indicator of an enclosure too small? Can you use fibrefill with a Velodyne? (I tried once before and it didn't seem to do much?)


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## bobduch (Jul 22, 2005)

Nath, could I get the schematics for the controller and servo from you?


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## dualmono21 (Oct 3, 2009)

sure thing buddy 
you still got my e mail addy ???
send me a message and ill attach the files for you 
sorry its taken so long to reply literally stumbled across your post tonight 

nath


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## Jimi77 (Jul 4, 2005)

bobduch said:


> Nath, could I get the schematics for the controller and servo from you?


Hey Bob, still floating around on the forums. 

Just picked up a 2001 Pathfinder - new build to start soon.


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## bobduch (Jul 22, 2005)

dual-you've got pm

Hey James. We need to meet up. I still need to meet baby Lilly.


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## Jimi77 (Jul 4, 2005)

bobduch said:


> dual-you've got pm
> 
> Hey James. We need to meet up. I still need to meet baby Lilly.


I've added a baby Kirk to the mix on Oct 17th. 

I'm getting snipped - these damn kiddos are driving me crazy. Not to mention cutting into my car audio time and budget.


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## bobduch (Jul 22, 2005)

Holy ____! I should be shot. Time is going way to fast. And congrats!!!


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## MikeGratton (Aug 17, 2012)

Some interesting history about servo subs 

In 1967, Arnie Nudell, PhD. was at work designing the world's first Q-switched pulsed ruby laser to be used in a laser rangefinder that would measure accurately the distance between an airplane and the ground. A servo-feedback system would then be used to control the inertia navigation system of the airplane for accurate positioning. During his laboratory work, Arnie realized that such a servo system would be able to also accurately control a loudspeaker, hence, the idea of a servo-controlled woofer.
Together with John Ulrich, Arnie designed the servo system and power amplifier to drive a woofer. Arnie called another friend - Gene Czerwinski - to make a special 18-inch woofer with a second winding on the voice coil to produce the feedback signal. The system worked! And the world's first servo-controlled woofer was born.
Together with an electrostatic panel developed by another two aerospace engineers, and a cabinet designed and built by Cary Christie in his garage, the first product was built - the Servo Statik I. This was in 1968, and Infinity was founded. Through the 70's Infinity grew until it was acquired by Harman International.
In the 80's, Arnie launched what was to be the first real high-end loudspeaker with the Infinity Reference Standard - or IRS. It was not originally meant to be a commercial product, but to be a statement of the highest reference standard for sound reproduction. It was the first speaker to use the Electro Magnetic Induction Tweeter - the first ribbon tweeter, and featured a line source of tweeters and midrange ribbons in a dipole configuration. It also had a total of twelve 12-inch woofers controlled by dedicated servo amplifiers. Nevertheless, the IRS proved to be a runaway commercial success. Excepted from; Genesis Advanced Technologies


John Ulrick’s account of the beginning;
We were supposed to be hard at work designing weapons systems for America - that's Arnie Nudell and me. Arnie and I worked at Litton Guidance & Control Systems in Woodland Hills, near L.A. We did build a weapons system, a laser rangefinder that measures the distance from an airplane to the ground for accurate bombing. We were also audiophiles, if there was such a term at the time. The year was 1967. I am an electronic engineer, Arnie a physicist. At Litton, my job was to design the electronics for the laser rangefinder and Arnie's was to design the world's first Q-switched pulsed ruby laser. This was the laser that supplied the pulse of light that went from the airplane to the "target" and bounced back, used to calculate the distance from the airplane to the target. Part of that system involved a mirror to point the laser beam at the target. I designed a servo-control system, which points the mirror and its switching amplifier. During lab testing of the servo-control system, Arnie noticed that the servo was controlling the mirror at 20Hz, a magic number to any audio person. Arnie had a good idea - why don't we make a servo-controlled woofer? We went across the hall to the Litton engineering library and found a book called Acoustical Engineering by Harry F. Olsen - the first bible of acoustics. The book had a page on Servo Controlled Speakers but no analysis, just a block diagram. We worked together to design the system. Arnie calculated the radiation resistance for the slopes and I designed the servo system and the power amplifier to drive the woofer. Arnie called his friend, Gene Czerwinski, to make a special 18-inch woofer with a second winding to generate the feedback signal. At the time Gene was an engineer at Bendix and making speakers in his garage. Gene later left Bendix to found Cerwin Vega. At this point one could wonder, who is making all these weapons systems? The woofer worked. There were two more aerospace engineers working at nearby Atomics International, Ron and Bob, making electrostatic panels. (The pentagon always said you must value the technology spin off from military research!) What a great combination, electrostatic panels that don't have much bass, coupled with an 18-inch servo-controlled woofer. The system was built and set up in Arnie's living room. Using a Sherwood amplifier to drive the electrostatic panels, the tweaking began. The amount of servo feedback changed. The crossover points moved and moved again.

Arnie and I decided to start a company. You could tell by the name there was no professional help in naming the company. The name was "Nutek" for Nudell Ulrick technology. We began selling a system called the "Servo-Static I" through a local dealer. The local dealer was about a mile from Litton and owned by Dr. Jim Henderson a physicist who you will hear more about later. All of this was still part time with a new guy involved, Cary Christie, a very talented industrial designer making the cabinetry in his garage. Arnie and I put out feelers to raise money and were finally backed by a rep firm that sold me electronic parts at Litton. No sophistication here either; we didn't even have a business plan because we didn't know what one was. A corporation was formed with Arnie and I holding equal interest. Fortunately, when we went to incorporate, the name Nutek was taken. The name Infinity was the third choice on the list, but available. The company name was Infinity, the year 1968. Again Arnie and I demonstrated our management prowess in choosing who was going to be the first president; we used the coin toss method. I was the president the first year and then we alternated for the first several years. What confusion! In August 1968 myself, Arnie and Cary and a couple of other people started full time in a 2,000 sq. ft. building in Chatsworth. Infinity was started. At the start, Infinity had three speakers; the Servo-Static I ($1800), the 2000, a bookshelf with electrostatic tweeters ($276) and the 1000, a 2 way bookshelf speaker. Excerpted from http://www.spectronav.com/tech2.htm


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## claytonzmvox (May 4, 2011)

use the VELODYNE without the servant thought so much better, do not believe the level of audible distortion is so great as to undermine the whole system.


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## claytonzmvox (May 4, 2011)

more considerations on the Velodyne?


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

claytonzmvox said:


> more considerations on the Velodyne?


It sucks by todays standards... move on...



roduk said:


> To all Velodyne owners - I have a DF10 and have used it for a couple of years now. I had a Soundstream Class A 10.2 Modified to play flat down as low as it can go by Gordon @ Genesis, it now sings after having all the LPF xovers removed and the power supply boosted up etc.. I am rebuilding the sub box atm and am wondering what effect it would have on the sub if it was smaller than recommended? 0.6-7 cubic feet as opposed to the recommended 1-1.5 cubic feet? I feel as if I'm getting a bit of a one note wonder atm - would this be a known indicator of an enclosure too small? Can you use fibrefill with a Velodyne? (I tried once before and it didn't seem to do much?)


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## claytonzmvox (May 4, 2011)

Aaron'z 2.5RS/WRX said:


> It sucks by todays standards... move on...


Why do you think they are outdated? Think you do not have value for a good quality system? I do not see many subs today with the quality of Velodyne. List of best quality subwoofers today!!


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## Brian Steele (Jun 1, 2007)

dualmono21 said:


> an "average woofer" such as the morel ultimo still has over 10% distortion a velodyne has less than 1% after the servo


The image below is a FR + distortion measurement I took of my current sub system (two Infinity Kappa 122.7Ws in a sealed box) at close to normal listening levels. I bought these two subs for $100 each a few years ago. The surrounds have been reglued as the original glue started failing a few weeks ago. The red curve represents the FR with the trunk open and the green with the trunk closed.

A couple of observations:

1. The distortion plots stay below -25dB (10%) all the way down to 20 Hz. 

2. For a good portion of what we consider "bass", the distortion plots stay below -40dB (1%)

3. Closing the trunk increases the bass level but also increases distortion between 50~90 Hz. Even then, it's still at or below -40dB (1%). And I have NO special damping in the trunk. I suspect that those who have gone the extra step and damped all panels in the trunk may see lower distortion figures.

Summary:

1. Low distortion is achievable with today's subwoofer drivers without any special processing required.

2. The environment that car audio subwoofers are going to be used in is likely to add its own distortion anyway.

I'll be replacing these two drivers with Alpine Type R 12D2s very shortly. I expect even better performance data from them.


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## spooldup (Aug 4, 2018)

They are the best sq subs ever made and that was me selling one of them back in the day.


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