High pass filter

[Warpdrv1]

Building Dual 320L 15" TC-2000 boxes... tuned to 14.5hz

I want to implement a High Pass filter to eliminate bottoming out my drivers below tune... Is there anything out on the market that I can buy that has a selectable High pass for my drivers...

Or

Maybe the only way is to build my own... If so, what would I need to make this product.

Any Ideas.... ?

[ThomasW]

eD is coming out with a little $100 box that will do this.

DIY Cable is coming out with "The Woofer Widget"

And finally Chasw98 and I are developing the H@LF Box

I think Rod Elliot has something as well..

[Warpdrv1]

Thanks ThomasW.... Appreciate that info... that Is more then I have seen in all my searches.

I have been following the eD product coming out, and it looks promising, but the lack of variable adjustment on the High Pass has me concerned.
5hz, 17.5hz, and 30 has its limitations for me... Unless the rolloff at 17.5hz isn't too steep, It could work... But based on this image, its rolling off even earlier before 17.5hz --- Perhaps this isn't a true measurement.



I will be following your project now, and look forward to new news about the others. In fact, your little box has everything that Im looking for in my future solution.

Is there another site that Im missing that has more info on these solutions...?

[chasw98]

Warpdrv:
With the solution that Tom and I are/have developed, you can literally specify the corner point of the filter using some fairly simple math. The unit I am using at home has modules that cost less than $3 each with frequencies at 8, 10, 12, 14, 16, 18, 20, and 24. The unit also offers unbalanced to balanced conversion which is perfect for placing the unit between the LFE output of your unit and a BFD that is balanced. The down side is that you have to build it. But also, the upside is you get to build it! Anyway you want. It is a very flexible little unit.

Chuck

[Warpdrv1]

That looks awesome Chas...
I don't mind making the attempt to build something as long as its straightforward and somewhat simple... Im no pro at small electronics, but love a challenge...

I love the idea of having the adjustments inside, so once set, they can never be touched... Thats a great idea...

What slope rolloff are we expecting from the selectable freq's. ?
***EDIT*** Found this also Hi Pass filter adjustable from 8 to 20 HZ 24 db/octave roll off

How long before we can get our hands on something like this?

Price Point for the H@LF Project? ***Edit*** Found this searching the site here, Looking at less then $50.00 plus powersupply and case, in a DIY config... Cool...

[chasw98]

I don't mind making the attempt to build something as long as its straightforward and somewhat simple... Im no pro at small electronics, but love a challenge...

I love the idea of having the adjustments inside, so once set, they can never be touched... Thats a great idea...

What slope rolloff are we expecting from the selectable freq's. ?
***EDIT*** Found this also Hi Pass filter adjustable from 8 to 20 HZ 24 db/octave roll off

How long before we can get our hands on something like this?

Price Point for the H@LF Project? ***Edit*** Found this searching the site here, Looking at less then $50.00 plus powersupply and case, in a DIY config... Cool...

If you can use a soldering iron and put the parts in the right holes, then it is pretty easy. The whole circuit board is no more than 4" X 2 1/2" at most. The idea behind it was to be able to mount it inside a piece of gear like a BFD or an amp and (Ron Popeil) set it and forget it. That way you can use the +-15 volts already existing inside a piece of equipment. But you can also mount it in an enclosure with power lights, external knobs and switches, so that you can fiddle with it. It is even possible to mount a DB9 socket on the outside and make up filter modules that fit a DB 9 male to switch out filters without opening up the box.

[Dennis H]

But based on this image, its rolling off even earlier before 17.5hz --- Perhaps this isn't a true measurement.

The filter frequency is the -3dB point so the graphs look accurate.

[ThomasW]

Found this searching the site here, Looking at less then $50.00 plus powersupply and case, in a DIY config... Cool...

The raw components cost exclusive of PS, chassis, and PCB is right at $50.

Right now I have couple very high-end prototype PCBs. My cost on these was $40ea.

If we decide to go forward with the project there will be a group buy for the PCBs and the price will plummet. There's no timeline for this, as a result it would probably be early January before PCBs are available.

[Warpdrv1]

Thanks alot guys... I appreciate the info, as well as your efforts involved in designing these, and hopefully getting them avail for everyone in the near future is awesome.... especially in a group buy scenario.....

I look forward to trying to DIY something like this, and doing more searching on the subject, using those Hammond cases like Habs4life https://www.htguide.com/forum/showpo...2&postcount=40 on some of his projects would be slick as H3LL.

The time frame would be really good for me...

[Warpdrv1]

Couple of quick question here.. I am currently running an SMS, with dual SVS subs...

I am just getting started on building 2 - 15" TC-2K 320L boxes. I am curious about whether I can use the H@lf Project units (thinking 1 for each channel) which will allow me to implement both Phase and Highpass filters for each sub.....
Pretty much thinking that I would put it inline after the SMS and before the amps out to the sub.. Correct my signal path here if Im wrong...

The only thought in keeping my SMS is whether or not Velodyne does indeed remove the rolloff filter... Subs will be tuned to 14.5hz, and eq'ing can be performed down to that point relatively easy with the SMS.

Oh also, can I run a single powersupply for both H@lf PCB's...?

Implementation Thoughts...?

Warp

[cjd]

You should be able to run a single power supply as long as it is capable of the necessary current delivery for two H@lf's. (does that make it a wh@le?)

I may throw together a quick'n dirty (as in simple, not as in poor quality power) regulated supply that could be (perhaps) included on the board to make this a one-shot deal if you add a small transformer. I may not. We'll see. It could make zero sense if this works best off a basic wall-wart.

C

[chasw98]

You can run a single power supply, IF it has enough current to power 2 boards. In reality, there are only 5 active IC's per board and they do not draw much power at all. I would think that 500 ma would be fine, but to be sure I would have to look up the data sheets on the IC's. I have started a schematic for a single ended wall wart transformer that will give a bipolar voltage with enough filtering to keep the noise out of the audio. That is at work. I can put this up here tomorrow. I can aso get the exact draw by the IC's so that you know how much power supply to use for 2 units.

Chuck

[Warpdrv1]

So now that we have some idea of someone using a powersupply for dual H@lf's or a (Wh@le) thats some funny $hit) How is my line of thinking for implementation of those units, after the SMS ? Do-able?

[chasw98]

So now that we have some idea of someone using a powersupply for dual H@lf's or a (Wh@le) thats some funny $hit) How is my line of thinking for implementation of those units, after the SMS ? Do-able?

I'm not real familiar with the SMS-1. The hi pass filter is adjustable from 15-199 Hz. Even though the unit has balanced or unbalanced input and balanced output and 3 discrete outputs for 3 subs. It is only capable of one 1 EQ curve for any sub connected to it. If you are using more tha one sub, you will probably not want the same EQ curve even if the subs sat on top of each other. What you are proposing will work. Placing 2 H@LF units after the SMS output will work, but I have to ask what are you trying to acheive? OR maybe what am I not understanding?

You would be much better off using a BFD that is being fed by 2 H@LF units or 1 H@LF unit to two channels. Then you can have seperate independent EQ of the SMS and make all the subs happy no matter where you position them.

And you cannot turn off the Hi Pass fiter in the SMS. You can only set it to its lowest point which is 15 Hz.

[Warpdrv1]

I wasn't aware that with a BFD that you could eq seperate channels...

All Im trying to do protect my drivers, and give myself the ability to Phase each sub, while still maintaining the ability to have simple EQ of the room. While the SVS subs have built in Phase, my new subs will not.

The SMS is to have a firmware upgrade to remove the Highpsss filter, because of the harsh rolloff the unit has. Currently as you more then likely know, the steep rolloff to me is the only drawback of the SMS.

My room requires very little EQ, high ceilings on one side, very little standing waves, and I thought if I could avoid buying another piece of equipment, I would give it a try.

Just thought I would consult the experts....

[chasw98]

I wasn't aware that with a BFD that you could eq seperate channels...

A BFD has 2 channels.

All Im trying to do protect my drivers, and give myself the ability to Phase each sub, while still maintaining the ability to have simple EQ of the room. While the SVS subs have built in Phase, my new subs will not.

In that case, what you are proposing will work just fine. With 2 H@LF you will have hi pass filter on your new subs and seperate phase adjustment on your new subs.

The SMS is to have a firmware upgrade to remove the Highpsss filter, because of the harsh rolloff the unit has. Currently as more then likely know, the steep rolloff to me is the only drawback of the SMS.

My room requires very little EQ, high ceilings on one side, very little standing waves, and I thought if I could avoid buying another piece of equipment, I would give it a try.

Just thought I would consult the experts....

If the firmware upgrade gives the ability to remove or to lower the Hi Pass filter in the SMS then that could be a good thing. I would wait and see exactly what the firmware upgrade does for the SMS.

If you use or need very little EQ, then you probably don't need a BFD. Having 2 SVS subs and 2 DIY subs all in the same room could lead to very tricky placement, EQ, and acoustic issues. You might also find that you will have 2 SVS subs for sale shortly. :B

[chasw98]

Dual Output Power Supply Using Non-Centertapped Transformer

Without a centertap, it is still possible to provide both polarities of output voltage but a half wave configuration must be used. This is similar to the wiring of a voltage doubler but we are using the common point as ground:
Here is a circuit for a +/- 15 VDC supply:

--REFER TO THE ATTACHED ASCII DRAWING--

For an unregulated supply, take the outputs from V+ and V-.
Since only half-wave rectification is used, the main filter caps, C1 and C2, should be at least twice the uF value compared to full wave or bridge circuits to obtain the same ripple.

Another disadvantage of this configuration is that if the currents drawn from the outputs aren't equal, net DC flows through the transformer secondary (with a voltage doubler having no output connection to the common point, this isn't possible). Core saturation may result if operating near the transformer's maximum current ratings.

This idea and schematic come from http://www.repairfaq.org/sam/samschem.htm#schslp1b
I have not bUilt this yet, but I think it will need some more filtering to be very quiet in actual use. The one advantage here is the ability to use a readily available wall wart transformer to provide the AC voltage needed for the supply to operate. This will save significant money if you don't need a separate fuse, power cord, enclosure, etc. for the unit.

I have attached the original ASCII drawing.

[Warpdrv1]

In that case, what you are proposing will work just fine. With 2 H@LF you will have hi pass filter on your new subs and seperate phase adjustment on your new subs.

If the firmware upgrade gives the ability to remove or to lower the Hi Pass filter in the SMS then that could be a good thing. I would wait and see exactly what the firmware upgrade does for the SMS.

If you use or need very little EQ, then you probably don't need a BFD. Having 2 SVS subs and 2 DIY subs all in the same room could lead to very tricky placement, EQ, and acoustic issues. You might also find that you will have 2 SVS subs for sale shortly. :B

I have no intentions on trying incorporate my SVS subs in with the new TC-2K's, they are replacements... SVS's will go to other areas of the house..
No point of trying to Blend the Two inferior subs with these, they will be way more then I need... And with the measurements/room response I get from my SVS's, I am more then confident enough I can keep the SMS if Velo. fixes their rolloff problem...

Thanks for your response Chas.... I appreciate it, and look forward to seeing how that power supply scenario comes together...

[Warpdrv1]

Well I just got the latest update from curt c at velodyne.....

SMS-1 v2.1.3 firmware update

Im sure it will be up on the website soon... if anyone is interested

I don't have the cable to install the firmware yet.. maybe tomorrow..

Subwoofer Management System (SMS-1) Release 2.1.3

Release Notes

This document discusses the latest release of Velodyne’s Subwoofer Management System (SMS) firmware – release 2.1.3. This firmware addresses two issues related to the low frequency management of the SMS. First, it allows the subsonic filter to be set low enough that the only remaining rolloff in the low frequency is restricted only by the hardware, and secondly, corrects some distortion that previous versions of the firmware introduced to the audio spectrum.



Figure 1: SMS-1 Frequency Response

Please refer to Figure one. This graph shows actual output from the SMS-1 with the subsonic filter set to 5 Hz. The various curves shown reflect the subsonic filter as set to 6, 12, 18, 24, and 30 dB/octave -- the steeper the slope, the higher the subsonic slope setting. As you can see, the actual point at which the curves converge is 5 Hz, and at 5 Hz, the audio frequency is down about 5 dB. The typical 3 dB down point is about 8 Hz. This point is a limitation in the hardware and the low frequency response of the SMS cannot be extended any further without changing components in the hardware. In release 2.1.3 the subsonic filter can be set as low as 1 Hz., but any setting below 5 Hz. has negligible effect on the frequency response.

Note that the low-pass crossover in this example is set to the default of 80 Hz and 24 dB/octave.

Some users of the SMS measured the low frequency performance and discovered that the SMS was adding some distortion to the lowest frequencies. Most users did not notice this added distortion due to the low frequencies affected. The distortion was inadvertently introduced as the frequency processing software, which was based on Digital Drive subwoofers, was rewritten for the SMS. The 2.1.3 firmware corrects this problem.

There was some confusion that this distortion was also present in the DD series. This is not and was never true – the distortion was introduced in the SMS only, and has now been remedied.

If you have any questions on this information, please contact Velodyne customer service at techhelp@velodyne.com.

[Warpdrv1]

Hey Chas or Thomas, any updates on your H@lf Box...? :T

[cjd]

eep!

Must. Finish.

C

[chasw98]

Hey Chas or Thomas, any updates on your H@lf Box...? :T

Yes, Thomas has gotten prototype circuit boards screened and manufactured at a really exorbitant price, but they have been made. I have 2 of the boards and have built a H@LF box fully using the board and a parts list I created at mouser electronics. cjd has been given a board and bought the parts to build one. He has a lot on his plate at the moment both life wise and audio wise and ryan (---k---) wise, so we don't know when he will get it assembled and tested. Mine is working quite fine, thank you. Contact Thomas with a PM if you are interested in one of the prototype boards or for more info on a large quantity buy we may do.

Chuck

[cjd]

I do have some suggestions: recommend pots that can be box mounted rather than PCB mounted! For beta it is, of course, fine.

Also, inputs, outputs, and power are not labeled at all clearly on the board.

And a schematic for a power supply for those less familiar would be slick. So easy to toss one together quickly but...

I'm working on it, it's just not done. I didn't have an amp it would work well with prior to starting the HT upgrade, and that, of course, is not a small undertaking. I can actually get to my work bench now though.

C