High pass quality to mains uisng Velodyne DD subs


For those who have incorporated one of the DD series subs into your two-channel system, did you use the line level high pass filter from the sub to your main speakers amp?

I have two sets of outputs from my preamp, so I could run one set to the sub and one set full range to my mains. I was just wondering if folks had experienced much degradation of signal going line level from preamp to DD to mains amp.

Theoretically, I like the idea of the high pass filter.

Getting ready to set up my dd18.


I have a DD15 and did not use the high pass filter. I much prefer to run the mains unincumbered.
Hi Rwwear,

I know the feeling, did you try it both ways?

No. Maybe someday.
Rwwear..."unincumbered"??? The idea of the crossover is to free the main speakers from the burden of unproductive LF cone motion.
I think Rwwear means he doesn't like the idea of having the mains encumbered by a high pass filter in the signal path. It would be interesting to hear the results of trying both methods.
Right Gunbei, thanks. Extra electronics in the signal path ya know.
Rwwear...Any degradation due to "extra" circuitry is theoretical, and could be expected to occur only for inferior electronics. LF cone motion is actual physical reality...not theoretical. It causes Dopler modulation of higher frequencies, and requires the driver to electically function over a large range of cone excursion that would not be present if the LF were filtered out.

By all means try it both ways, and do what you prefer. In all likelihood you will hear no difference with the typical lightly driven home audio equipment, but a Pro Sound rig, driven to its maximum capability, would be a different story.
I have asked the same question a couple of times without getting any answer, but I intend to purchase a SMS-1 and will certainly try the high pass. A better way to minimize the tradeoff between transparency and distortion may be to use a separate high-pass filter like ACI's for the satellites, or to solder a high quality capacitor in series with the main amp. There is a formula to derive the required value according to hinge point and amplifier impedance.
Looks like no one has A/B'd this. Within the next few weeks, I'll be able to give a try.

If I find that the higpass is benefical, but a little noisy, I may go for an outboard crossover like the the vandersteen m5-hp. The savings on long rcas's of even moderate cost would about pay for it.

Thanks for the responses.

Vladimir...The capacitor idea is attractive, but...

1. The capacitor will give you only a 6 dB filter. It will significantly impact frequencies well above where you want to make the crossover.

2. The capacitors used in a line level filter will be of much smaller value than those of a speaker level filter and can be of the highest quality for less money.

3. The 6 dB filter will cause a 90 degree phase shift. An active line level crossover with the ubiquitous four pole L/R 24dB characteristic has a 360 degree phase shift, which is back to 0 degrees.

4. Active amplification in the line level filter is just several unity gain impedance buffering stages. These are easily implemented with almost unmeasurable distortion.

5. With a capacitor you will not be able to easily experiment with different filter frequencies. You will probably want to do this. Personally, based on much experience in this matter, I go so far as to vary the X/O frequency according to the particular music I am playing, and this requires a crossover with a frequency selection knob.

I have done the capacitor thing in the past, and I think that item 1, above, is the killer. Try it by all means, but experiment with inexpensive capacitors until you decide what you want.
Vladimir, you should take note that using the SMS will overide the servo control in Velodyne's subs and I would guess in others as well. That's the only reason I don't use one with my DD15. If your sub doesn't have servo control then it will not matter.

I'm not following your last comment. The DD15 comes with the SMS built in. Are you not using the built-in low pass and equalization?
Yes it does and I am but I would like to have one just for the fact I could see the readout without a TV. And it will control other subs.
Eldartford, I guess your points make sense. By the way, the Velodyne high pass is also 6dB/octave.

Rwwear, I know what you say, but I would use the SMS-1 with my current REL and maybe an ACI Force later.
Hello Folks,

I own a DD15 and Dynaudio S1.4 speakers, and I have tried using the sub both ways.

Using the crossover and high passing the mains is the much better real-world choice. Every major sonic attribute is imrproved when you do this, all the way through to the midrange tone and transparency.

When you use the high pass, your midrange driver is freed from having to try and reproduce the bass along with the midrange in the same driver. The amplifier is also freed from the burden of dealing with the bass frequencies.

These advantages outweigh any theoretical "more circuitry in the signal path" problems by orders of magnitude.
Thanks for note goatwuss.

I'm going to try it out both ways when I get the chance and report on it.

Crossing over my front DLS 3-ways in my car a little higher made a huge difference there.
I tried both ways. I was running Running two DD 10's. It was a trade off in my system. Using the high pass in the subs made the speaker and sub intergration perfect. But it made the mids and highs sound electronic.

And by not using the high pass, and just using the room correction, I could never get the seamless intergration with the main speakers. I ended up selling the two subs and bought a better full range speaker. Now their is no trade off.
I really think it depends on the main speakers you're using and what your aim is in using crossovers.

In my home theater using the processor's crossover does wonders. The active network seamlessly blends my NHT satellites and sub creating a very coherent movie experience.

However, in my 2 channel rig I've found using any kind of crossover destroys the beautiful midrange of my ProAcs. Upper and to some extent midbass contribute to the way we perceive overall midrange, and the midrange of the ProAcs suffers greatly even if I set the crossover to 35Hz. The associated equipment I've chosen enhances that midrange and any attempt to place a filter before the ProAcs recesses the midrange and compresses the sound.

However, if a more balanced, neutral sound is your goal, use of a high pass filter could depending on the speaker and intent be very beneficial.

Like Dlanselm, after trying to integrate monitors [in my case ProAcs] with a sub I have since gone to using full range ProAcs without a sub.
I tried it out both ways last night with my (very) old Vandersteens and the high pass had obvious benefits in both cleaning up the midrange integrating the sub.

I also found that my plans to improve room acoustics are badly needed because quite bit of equalization was needed to flatten out the LF.

I had some noise/degradation, but I was using extremely crappy interconnects (hardware store quality) because that is all I have in long lengths.

The benefits look big enough that if I end up with speakers that like the HP this much, I will probably subtitute a high quality HP like the Vandersteen 5m-hp for the Velodyne HP. Then, I can use my shorter current higher-quality cables (with one addition) also.

I guess that what I am saying is that I am not going to throw in the towel if it turns out that the velodyne HP is not up top snuff. Another advantage of skipping the Velo HP is that I can then attenuate the input to the Velo - I'm running at volume 3-5 out of 100 now with 2-channel.

All of this won't matter if I end up with the Merlins since they have a built-in HP at 28 Hz as part of the Super BAM and others have had good lucking integrating them full range as they stand.

Please keep adding comments. I consider this to be an important discussion since we probably can't buy a floorstander that is clean to 15 Hz for less than about $20,000, if that. Personally, I also value the ability to use the sub for HT with a totally different set-up.

Also, I could not identify the source of the bass whatsoever with just one sub. I was using a very steep crossover, though. I am perfectly happy to add a second if it can be demonstrated that I am missing something.

With a second sub, the sound stage had much more dimensionality . It was night and day better in my system.
I have been a fan of subwoofers ever since they weren't mainstream because having clean 20Hz reproduction is much more than just getting deep bass; it also does wonders for soundstaging and imaging since most of the ambience of the original venue is hidden in the very low frequencies. Jerrym303 is also right in that there is no "full range" speaker at a reasonable price and, on top of all that, Velodyne's digital bass correction is the state of the art and too good to pass. I would try ACI's high pass filters(only $29), plus plugging the satellite's reflex ports (if any).