Phono Stage upgrade to complement Dohmann Helix One Mk 2

@lewm

So, with the Velodyne Digital Drive subwoofer, the entire line goes through the subwoofer from the pre-amplifier? And the Velodyne has both a high pass and low pass filter, which the high pass filter line then goes to an output line into the amplifier, and the low pass filter signal is delivered to the subwoofer?  Or, would I still have a direct line from the pre-amplifier to the amplifier that goes through a high pass filter, which would either be analog, or, if digital, need an ADC and DAC?

(And the amplifiers are the Ypsilon Hyperion (input impedance 22k Ohm). I previously had Atma-Sphere MA-2, which were also very good.)

"So, with the Velodyne Digital Drive subwoofer, the entire line goes through the subwoofer from the pre-amplifier? And the Velodyne has both a high pass and low pass filter, which the high pass filter line then goes to an output line into the amplifier, and the low pass filter signal is delivered to the subwoofer?"

So far as I can tell from reading on the internet, the answer is "yes".  The electronics in a DD+ Velodyne can do it all for you. But you can opt to drive the main speakers direct, using an in line capacitor to effect a passive high pass filter (or any other way you like to effect a high pass filter).  One or the other, not both.  I personally would NOT go digital for the high pass filter. There is just absolutely no need for it. Mijostyn would disagree.

@lewm

Is there such a thing as an active analog high pass filter, or are all analog high pass filters passive?
Thanks.

Dear @drbond  : Any electronic device is active with it's power supply.

If you don't want to go direct to the amplifiers then you need that electronic device as this one:

https://www.jlaudio.com/products/cr-1-home-audio-subwoofer-crossovers-96020

R.

Drbond, the filters built into most subwoofer electronics are active and analog. Unless explicitly stated, the filters in an outboard electronic crossover are analog.The only passive filter mentioned so far is the idea of using a capacitor in series with the main amplifier input to effect a simple 6db high pass filter. Everything else is active . If you want digital filtering I know nothing about what’s available, and I personally wouldn’t go in that direction.

@lewm 

Thanks for the clarification.  My favorite pieces involve the cello or cello and piano.  (Yes, Bach, but also Beethoven and Brahms.)  Consequently, I was thinking that the crossover should be below the lowest cello note, which is 44 Hz, as I wouldn't want the cello to sound like it's jumping around. 

 

Hmmm…this subwoofer project is looking complicated:

often it does…
Many do it digitally, and that is a lot easier some ways.
However if the main analogue chain is nice, then we can complicate it with an analogue approach, which is in fact a bit simpler.
(But there are many ways to skin a cat)

it seems like an ideal approach would be an in line high pass filter after my pre-amplifier, but this would have to be an analog filter, correct?

That is one way, and usually it is the one that has the minimum detriment to the signal chain. And even with this HPF, one can use some DSP on the sub to flatten the response a bit.

(I can see myself reacting to a cello that sounds like it’s in one place for the higher notes, and another for the lower strings/notes…)

A cello sounds like it is in the same place as the higher notes of the instruments harmonics locate the cello, and low notes reinforce the fundamental tone.

When it is done right then it is not apparent that the sub is even on.
But if one turns the sub off, then it is apparent.

And it often sounds best when it is turned up to the point that it is apparent and backed off to the point where it almost seems like it is not contributing.

Set up well it is like PFM (Pure Magic).

…or replace my pre-amplifier, which I really enjoy listening to, with a digital pre amplifier that has filters built into it…which I am averse to do…

It is ^here^ where the in-line HPF is an elegant solution.
It sound great now, you just a bit more of low notes, and remove having to force the main speakers from trying too hard to play those low notes.

With the HPF, one just tapers off a major portion of the power to the main speakers, as the lion’s share of power is used for pushing air in the low notes. And then the sub takes that over and tapers off the power as the notes enter back into the main speakers in a smooth fashion.

And then all the IMD and Doppler distortion of the panels having to wave back-n-forth as the high note are also coming off of it… becomes reduced as most of that waving gets shed to the sub.

Doing this at a knee of 100Hz is not uncommon with a 1st order slope.
Some people go high with higher slopes.
And if the sub resonates or has harmonic, or noises, that locate it in the room, they they might cross it over lower.

If one fancies the idea biasing the dielectics, then the HPF get some extra stuff in it, but it behaves like a single capacitor.

drbond, This thread can go on and on with different ones of us giving you different advice. To avoid further confusion, I suggest you read up on the options by searching on line.  Terms you need to understand are "active crossover", "passive crossover", and something about how slope of the high and low pass filters comes into play. I don't agree with Holmz in some cases, but for me to debate Holmz here would only confuse you further. Suffice to say, as I said before, a properly integrated subwoofer will not give you the sensation that the cello is jumping from main speaker to subwoofer and back again.  On that score, Holmz and I agree. On the other hand, I am not a fan of digital filtering or digital shaping of the response.

@rsf507 talking about $60,000 Phono stages is not that relevant to most people either. 

@rauliruegas , since I design and build my own subwoofers and analyze the results I know a lot more about it than most audiophiles. Putting a 1st order high pass filter on the amplifier input is a last resort. 4th order is more like it. You are much better off with a digital 4th order high pass filter than an analog one.

mijostyn

Your opinion is the knee jerk reaction of a traditionalist. Your assumptions are patently false. You are entitled to stay where you are. There are people who prefer being dinosaurs and that is fine ...

Why so angry? Why are you so triggered by those whose opinions differ from yours? Why do you feel others need your permission to disagree?

Unfortunately, the more I read about HPF, the less inclined I am to use them: everything that I’ve read so far indicates that their use does impact SQ.

Additionally, here’s a paragraph about higher order HPF influencing signal moreso than lower order HPF (but it is just the internet, which could be wrong):

Although there is no limit to the order of a filter that can be formed, as the order of the filter increases so to does its size. Also, its accuracy declines, that is the difference between the actual stop band response and the theoretical stop band response also increases.

Learning about subwoofers is an exercise! I’m not sure whether I should proceed in this direction, given the components in my system. . . although, it would be interesting to compare any differences in SQ with a properly installed digital HPF with subwoofer, which replaces my pre-amplifier / amp / ESL system currently. But that might be a project for another time. . .

@rsf507 talking about $60,000 Phono stages is not that relevant to most people either

@mijostyn agree but it's a more interesting read than all this talk about sub integration. At least start a separate thread on subs. That was my point.

There are pros and cons to any decision. Yes, take your time to find your own set of goals and the best methods for achieving them. It’s more fun that way, besides.

@rsf507

Yes, to a casual observer, you may wonder why we are talking about subwoofers on a thread that started with phono stages. Well, the phono stage question was resolved rather quickly and emphatically in the first few pages of the thread, with a brief foray into amplifiers. However, three of the five of the regular contributors to this thread all have the same ESL speakers, so that’s probably the main reason I thought it was best to continue any detailed discussion about my sound system on this thread, as opposed to starting another one in the speakers section. Additionally, there are many other factors that one can consider: I think that individuals that listen to vinyl have a sound in common that they appreciate; additionally, at the level of system we’re talking about, I would probably have to sort through a hundred posts about average equipment; whereas, here, most realize that we are discussing very high end equipment.

Thanks.

@drbond : "" I was thinking that the crossover should be below the lowest cello note, which is 44 Hz, as I wouldn’t want the cello to sound like it’s jumping around. ""

As lewm posted and this tstaement confirmed you are a truly novice on sub’s integration to a room/system. That " jumping around " never happens with not the " ultimate " subs/speakers but with any just decent integration.

As lewm posted almost all sub’s in the market comes with lo/high pass filters so you don’t need to add other part but IC cables and that’s it.

Don’t ask your self, as you did it, that will be a " degradation " before your sub’s integration for that trial/tests because the rewards here compensates any degradation you could think. Do it a favor: " don’t think or imagine ", you was who posted to make that trial/test so and with all respect just do it, up to you but can’t pre-judge before listen it. Again, sub’s are not like a change of amps or a cartridges or tonearms, is totally new for you: how can or could you pre-judge with out listen it in your room/system?.

Velodyne is only an option to make that " trial " and if you don’t like just return and put on sale the sub’s. No, the crossover frequency must be not at " 44hz " but at least at 80hz to take advantage of all sub’s/speakers/amps rewards.

Btw, any top room/system ( like yours. ) with passive speakers receives several rewards with the sub's integration.

R.

@rauliruegas 

Yes, you would be correct that I have no experience with subwoofers.  Does the Velodyne insert into the system between the pre amplifier and amplifier, with both a LPF for it's own amplifier and an internal HPF that then is sent to the monoblock amplifiers?

Yes, and that has been written here above over the past several days.  If you buy a modern Velodyne sub, you would need nothing else.  It comes with a built in two way crossover and an amplifier dedicated to driving its subwoofer.  It also comes with a microphone and the necessary circuitry to set up the subwoofer for best flattest response.  I was wondering why you seemed to feel that introducing a subwoofer also meant you would have to give up your present preamplifier (to go digital for some reason) and even your main speakers.  Not so.

I don't agree with Holmz in some cases, but for me to debate Holmz here would only confuse you further.

Or maybe it would not?

Suffice to say, as I said before, a properly integrated subwoofer will not give you the sensation that the cello is jumping from main speaker to subwoofer and back again.  On that score, Holmz and I agree.

And we both are advocating use of a high pass filter between the preamp and the amp. I just buy mine, and others use a capacitor.

On the other hand, I am not a fan of digital filtering or digital shaping of the response.

People with DACS and streamer, and CD players are alreadily heaving inverted in digital tech…

It is easier to tolerate a DSP on the sub chain side.
And the HPF solutions we are both talking about are on the main L/R channel side,.

I am still trying to figure out the difference other than manufacturers sticker.
It looks like you fancy the Velodyn and I like the Vansdersteen.

Unfortunately, the more I read about HPF, the less inclined I am to use them: everything that I’ve read so far indicates that their use does impact SQ.

Well is there a link to that?
And is it a digital or analogue HPF?

Additionally, here’s a paragraph about higher order HPF influencing signal moreso than lower order HPF (but it is just the internet, which could be wrong):

There is slower transcient response, but if you have a speaker with a crossover, then I am not sure one can be a purist.

Although there is no limit to the order of a filter that can be formed, as the order of the filter increases so to does its size. Also, its accuracy declines, that is the difference between the actual stop band response and the theoretical stop band response also increases.

I think you might be talking about speaker level XOs that have the inductors.

The ones with capacitors are not large, as they are RCA level. The big ones are the size of a couple packs-o-smokes.

@rauliruegas @lewm

Which Velodyne subwoofers would you recommend for best match and highest quality? What about Martin Logan subwoofers, or other brands?  (Velodyne has no photos of the back of their subwoofers and no diagram of connections on their website or downloads; the only Velodyne video on YouTube is 20 years old.  It seems like they're trying to hide something!)

Thanks.

@holmz 

I was just reading multiple reviews about various HPF and they all say that there is a noticeable affect on SQ.  But I suppose it's worth a trial.  The current problem is finding the best ones to initiate this trial with:. Vandersteen, Martin Logan, or Velodyne?  (I suppose Magico would be an option if it weren't a trial, but a definite move.)

Correction: I finally found a diagram of the back of the Velodyne subwoofers under quick start guide on their website. . But it’s a very poor diagram, and doesn’t explain anything about the HPF, LPF, etc. It looks like their target is the home theater crowd. Martin Logan website is more informative, actually has good diagrams, and mentions the difficulty of incorporating subwoofers with ESL, but they only appear to have LPF, which would need an external HPF, etc, which gets into the issue of SQ.

Velodyne DD+, 15 or 18 inches.

ML probably make a good woofer too.

If you are going to draw conclusions by reading websites, you’re likely to do nothing. It is impossible to conceive that a high pass filter would have zero (measurable) effect on the upper frequencies, mostly in terms of phase shift, not distortion so much, unless you use a bad electronic crossover. The question is can you hear it and if you hear it do you like it? The reason for using 6db/octave (passive with just a capacitor or active using an electronic crossover) is to do as little damage as possible to frequencies above the crossover point, in terms of phase shift. If you have questions about the ML subwoofers, it would be best to either look for a good review on line or to call ML and ask. I don’t know how I got into the role of a person urging you to try a subwoofer. In the Velodyne website and elsewhere at sites selling Velodyne, there are usually good photos of the back of the subwoof showing connectivity. I looked at a few last night. For me it was easy to see there are inputs for the preamplifier output, outputs for high frequencies to go to a main amplifier, and of course the low frequencies go to the built in amplifier that drives the woofer. There are many other choices of connectivity also offered; one would not be using every single input and output in any single installation. If you buy a Velodyne, there will be a book explaining in great detail how to install and use. Never fear that.  Better yet, in your case I recommend you get a local dealer to do the install and explain it to you along the way.

@lewm

because of the quality components of the pre- and amp, I am leaning towards an capacitor HPF, as opposed to running it through the sub, which just has a standard 6db per octave HPF, which would just be a standard, probably low-grade capacitor, correct?  A silver Duelund CAST capacitor in line with the two components, and then a separate line to the subs: it seems that Martin Logan subs might fit in the system better, since they also make ESL, and are more designed for a two channel system.  It seems that the Velodyne is for multi-channel home theatre use.

@drbond , you will hate any analog high pass filter. To operate a subwoofer correctly all filters have to be digital. The highest quality units now use 64 bit floating point processors and have none of the issues older units had like the volume control problem. Conversions in and out of 24/192 are invisible. 

@lewm correct. IMHO the Velodyns are mid Fi. The Balanced Force MLs are superior in every way The Magicos Q series, also balanced force, are the best on the market because of their extremely stiff, heavy enclosures. Because the electronics in all subwoofers are sort of second rate I prefer passive ones. You can only get these in kit form or build them yourself. Otherwise you can just bypass the electronics. This is mandatory for the filter section. Some class D amps are tolerable for subwoofer duty but the best bass I have heard comes from A, AB amplifiers with vanishingly low output impedances. The JC 1 is a killer subwoofer amp. These produce way too much heat to put in an enclosure. Only Class D amps are efficient enough for that.

@mijostyn

Understanding that digital LPF is better for sub woofers, can a high grade analog capacitor (e.g. silver Duelund CAST) be used for the HPF to the ESL with good results?  What’s the main disadvantage to using an analog HPF via an in line capacitor and a digital LPF to a subwoofer?

What are the higher end passive sub woofers on the market? (I do have an extra couple of amplifiers (class A and AB) sitting around).

I only chose Velodyne as an example of a good company that’s been making and selling subwoofers for at least 30 years. I am aware that for very big bucks Magico and others also make subwoofers. I’ve never heard them and the question was how to incorporate a subwoofer with minimum effort not what’s the best subwoofer. I don’t live in your world of absolute certainty and perfection but you’re entitled to your opinion. However it would be nice if you acknowledged that you’re stating an opinion or in this case a set of various opinions.

drbond , you will hate any analog high pass filter.

^That^ is a bold statement.

And how do we reconcile the fact that most speakers have a crossover in them, and those are analogue?
(Or are we throwing that out because the ESLs may not?)

While I generally appreciate digital, when one has a nice analogue system, there is an allure in keeping the front end free of digital.

To operate a subwoofer correctly all filters have to be digital. The highest quality units now use 64 bit floating point processors and have none of the issues older units had like the volume control problem. Conversions in and out of 24/192 are invisible

The idea that a sample rate and bit depth used for recording bats and other high frequencies is “required”, starts to fly in the face of logic.
Couple that with people tolerating many % of distortion in the lowest registers makes that paragraph a bit absurd.

I like digital as much as the next fellow, but one could just about do the math with a slide rule or abacus and keep up, and the idea of 64-bit math for the signal that has the highest amplitude in the spectrum means with probably could do it with 8-bits and 500 samples/second.

But if you are saying that the HPF for the main speakers should be 24bit/192k or something like that, then I have no argument. One pretty much needs that to keep the HP stuff that is going to the main speakers sounding good at 20kHz and beyond.
 

… can a high grade analog capacitor (e.g. silver Duelund CAST) be used for the HPF to the ESL with good results? 

Of a battery biased HPF.
Is your connection from preamp to amp RCA or balanced?
(I am guessing XLR if you ran Atmasphere amps at some point.)

I cannot figure out a way to post a photo of the inside of my Vandy M5-HP (high pass filters), and I have the older RCAs as well. The XLR ones have a row of dip switches for matching to the amp’s input impedance, which then makes the knee of the curve exactly at 100Hz.

I am not overly “bowled over” with the battery biasing cables, but perhaps there is something to it. And the cotton and silk covered cables do not have the dielectric polarising issues… and people rave about them… so maybe it makes a difference.

What are the higher end passive sub woofers on the market? (I do have an extra couple of amplifiers (class A and AB) sitting around).

The powered subs are more of a system, and there is an allure to having a sub that either comes on when the rest of the system does, or has some efficient amp that can be left on.

Other than power outages, mine was on for 20 years in the old house.
I rarely even thought about it… it just sat in the corner.

While I am intending on some DIY jobs for the new house, a lot of that is for Feng Shui and WAF… and there not a lot of choice in my location nor places to find them in the wild or in shops. In FLA they should be “springing up” somewhere.

@holmz

My pre-amplifier has two outputs: RCA and XLR, so I can run the RCA to the amplifier and the XLR to the subwoofer, or vice-versa, as the amplifier has both RCA and XLR inputs. I was leaning towards a lower crossover for the HPF, somthing like 80 Hz, or maybe 60-80 Hz, to keep the midrange in the ESL’s. The input impedance of the Ypsilon Hyperion is 22 kOhm, and I was looking at a silver capacitor to make the HPF happen, although, I’ve got much to learn about the science and the curves.

I figure I could use a digital LPF crossover for the subwoofers, since the signal to the bass might not be so noticeably affected by the change.  

Dear @drbond  : As you go followwed reading through google you will make more false assumptions as that one that Velodyne are more for multi-channel HT. Your ststement is not only false but wrong Nothing bad with that because you are or better yet you want to be a newcomer to the sub's room/system integration.

ML is no better than Velodyne: the cone are made by aluminum even Paradigm carbon X and the kind of fiberglass by Velodyne surpass the ML and as almost all subs ML uses too     las D amps but there is something crucial that in this thread already was posted and that crucial issue is that we add subwoofers in our high end room/system first to make the IMD and THD goes as lower we can and this issue is to improve severely the whole room/system quality performance ML only bla, bla, bla, in its site ( I know that this bla, bla is something you like it. Ok but means almost nothing ) but with out facts/measures no other but Magico shows its sub's THD a 20hz full SPL.

Velodyne 12" has a better and lower measured frequency response than the ML. So What's your deal about?

Do you think that all those subwofeers manufacturers that use clas D amplifiers all those amps are almost the same ? yes?  wrong all those amps are different because each used woofer is different, its self unique characteristics  demads that the amplifier can achieve what that woofer     needs to shows at its best.

No, your class A or AB you own can't even the woofer needs and this means higher distortions.

@mijostyn  is the " worst "  ( no offense. )  audiophile gentleman to take it as an example because what he found out was the " holly grail " on that bass rangebut that " holly grail " is only his " holly grail " . He likes to play with his computer/digital that at the ends he used as a very advanced digital equalizer because he manipulated the system frequency response on  some discrete frequency to tame the tone color to the tone color that likes mijostyn. Fine with me but not my cup of tea because it does not make sense to put all his efforst in analogue TT/TONEAR/CArtridges and the like when the system signal at the end the signal coming from his speakers/subs are both digital that pass through two filters: ADC/DAC. Again fine with me.

Silver Duelund cap?, ( no offense please ) but you are the typical audiophile that as higher its price has to be better when that Duelund is no more that a mid-fi capacitor. You can read my capacitor thread where you find out several links and first hand experiences with information why the Duelund is mid-fi and what is the role of a cap that has nothing to do with its price. You are a novice too on caps., even some manufaturers of speakers  too.

My opinion is that your first step in the " rigth " direction to trial sub's is not the external HPF but a complete subwoofer unit as the 12" Velodyne ones.

R.

Mijostyn, Speaking for myself only, I am curious to learn what you use to effect steep crossover points in the digital domain. 

I didn't state it previously, but the crossover is a matter of trade-offs.  Mijo makes the case for a very steep hi-pass filter.  The rationale for that is you want as much as possible to reduce the burden on the main speakers to produce bass frequencies.  To do that, of course a steep HPF slope is in order.  The problem is that filters with very steep slopes are very likely to color the upper frequencies (because a lot of parts are needed to effect a steep slope, each of which is likely to reduce fidelity) and to introduce phase shift.  (I am not convinced phase shift is such an audible problem if kept moderate, especially with our dipolar radiators.)  One reason I am intrigued by the Pass XVR1 is that it can do a 24db/octave slope with Linkwitz-Riley character.  In L-R, the phase shift is no worse than that of a Butterworth 6db/octave filter. The XVR1 is a stand alone electronic crossover; in theory you would use it with a subwoofer that had no built-in crossover and which was driven by a separate outboard amplifier.  Does anyone know of a commercial subwoofer with built in x-over and amplification that also affords a L-R filter?  On the other hand, selecting a HPF with 6db/octave slope, whether done actively (using whatever HPS is built in to your chosen high end subwoofer) or passively, using a capacitor in series with the amplifier input is least likely to do harm to the main speaker's output.  Obviously, in a given case with lots of $$$ having been spent, a steep HPF might sound great.  That's why I am curious to know what Mijo uses for a digital filter ahead of his speakers.

drbond, for your amplifiers with a 22K ohm input impedance, about an 0.1uF capacitor would give you a HPF at 80Hz, 6db/octave, assuming a single-ended input.  My choice among capacitors I have heard would probably be a Russian SSG silver mica capacitor,

Hi drbond:

I’m using the KRONOS PHONO PREAMPLIER.

I only can say that it deserves a chance.

I could use words to describe the sound and silence, but 

much better if you can test it. No come back.

Can support all LOMC.

I enjoy the electrostatic sound of SOUNDLAB U-545

and Atma-Sphere. The combo is magic when you feel all details.

Regards,

My speakers are Soundlab 545

I would suggest that going a bit slow is not a crime.,, and doing it right can be a chin-scratcher.

You can call or find dealer and look at what is on offer.
And some manufacturers answer the phone.

I could not find Velodyne, but Martin Logan has a bunch of dealers around Sarasota, and Vandersteen in Miami or Atlanta.

My pre-amplifier has two outputs: RCA and XLR, so I can run the RCA to the amplifier and the XLR to the subwoofer, or vice-versa, as the amplifier has both RCA and XLR inputs.

That works if the sub needs an RCA input and has its own filtering scheme.
I have not been overly shy in liking the approach of pulling the signal off of the binding posts.

I was leaning towards a lower crossover for the HPF, something like 80 Hz, or maybe 60-80 Hz, to keep the midrange in the ESL’s

Again I have not been shy in advocating the 1st order (6 dB/octave) at 100Hz.

• You attach the HPF at the amp side of the cable.
• Attach the line level cables to the speaker posts.
• Turn some pots on the back to set the levels.

and then you’re I’m done.

I would suggest seeing what the fuss is about, and if you go with a Velodyne or ML, then you at least went in with the eyes open.
 

Holmz, the first two of your last 3 bullet points would result in bypassing the main amplifier.

Hmmm. . .I’m back to the consideration stage: apparently, the most neutral approach to add a HPF in my current system is via a high-grade capacitor. However, these capacitors only give a 6 db / octave adjustment, which means starting at 80 Hz (so that the mid-range isn’t affected), would only drop the volume by 6 db at 40 Hz, which is the lowest sound played by the cello, although the piano may drop to 30 Hz on occasion, which would give about a 9 db decrease in signal to the main ESL speakers.

To put things in perspective, one click on the volume knob on my pre-amplifier is about 2 db (and it is usually set around 26 clicks) so we’re talking dropping the volume only 3 clicks for most low frequencies, and at most 4 clicks for the lowest, which is only going to be about a 10-20% drop in volume for these frequencies.  So I’m not sure a standard analog capacitor HPF is going to make much of a difference in attenuating the signal to the main ESL’s; and apparently, the built in HPF in subwoofers are also the standard 6db / octave. Ideally, I would get a high quality analog HPF, which would minimally affect the SQ, and filter at 24 db / octave. . .but that may be like the tooth fairy: impossible!

@holmz , Not at all. You ever tried an analog crossover on ESLs? Wel I have, several ones and they all turned out to be awful in the end. You can do it but there are far superior ways.

@drbond , 6 dB/oct is no where near fast enough to get the drop in distortion and increased head room I have been talking about. My filters are currently 48 dB/oct and the only way you can do that in an invisible fashion is with digital crossovers. I have been through every permutation of this problem some several times and have lost a lot of hair over it. If you do not want to use anything digital in your system you are better off without subwoofers otherwise they will drive you nuts and you will have wasted a lot of money. Subwoofers have to disappear into the music. You should not know they are there until a very low note comes along. In order to get the benefits of lower distortion and increased headroom, critical for ESLs you have to cross over in the area of 100 Hz which makes life even more difficult. Subwoofers also have to be placed in specific locations in order to work well. They are over 6 dB more efficient against walls and even more in corners. You also eliminate some (but not all) of the room interaction this way. This places them three to 5 feet behind the ESLs. In order to get the speakers aligned in time the ESLs have to be delayed a little. You can only do this in the digital domaine. Any other approach is a compromise you are not going to like. 

@lewm , all my filters are digital. I can select any slope and any frequency at 1 Hz intervals and I can make adjustments on the fly from the listening position. This is TOTALLY different than analog filters. 

@rauliruegas , I have heard you say on multiple occasions that digital reproduction is not just a little, but far more accurate than analog. Have you changed your position? I have owned Velodyne Subs and have listen to some of the more current models. I would never have one in my system. There are many great woofer drivers out there now. The differences in the good ones are relatively minor in comparison to the differences in enclosures. There is not one commercial subwoofer I would have in my system, not one. Not even the Magicos (to effin big!). But in order to have a chance at being uncolored the sub has to have two drivers at opposite ends of the enclosure operating in phase. This keeps the sub from shaking at volume which causes distortion. The only commercial subs that do this are the Magico Q Series, Some of the KEFs and the ML BalancedForce series. The best way to avoid driver distortion is to use large ones of high quality. The amps used in any of these subwoofers are compromised because they can not produce significant amounts of heat. They also have to fit within the subs and the manufactures want to keep them small. IMHO passive subwoofers with outboard electronics are the only way to go. I double darn guarantee that not one subwoofer plate amplifier can produce the bass of a JC1. Unfortunately, this is a much more expensive approach but that is life. 

Now as for as my turntable is concerned. If I remember correctly your most significant concern with phono stages is an accurate RIAA correction. My phono stage is connected to a Lynx Hilo, a studio ADC, DAC router. The phono stages output is set to flat (no RIAA correction) and the correction is performed by a program in my audio computer. It is way more accurate than anything you can do in the analog domain, very cool. You should try it or are you going to be one of those stuffy analog only guys. Good luck trying to find an analog record now a days.

Mijo, my question was specifically what are you using to provide digital domain filtering, that is, what brand and model? Thanks.

Here on Audiogon and elsewhere there are always a plethora of good high power solid state amplifiers for sale pre-owned at prices far below the cost of a new JC1. You’ll say the JC1 is best and I’ll say we’re only talking about the lowest 2 octaves of low bass. I’d look for a Threshold or Krell or any of many other good choices. In fact one might find a used JC1. I do also like the force cancellation idea.

Dear @mijostyn  : I did not change my way of thinking on digital reproduction. The issue is that I don't mix analog / digital at same time.

When I'm listening to analog I want to listen the analog alternative colorations and when I listen to digital I like to hear the digital color.

You are totally immerse in digital and nothibng wrong with that because it's what you like it. Maybe in the future I could be immerse in digital too but not now.

Analog has its own and specific color and digital too but way different. drbond is now thinking to mix it, fine for him.

As I already posted your holly grail is just yours and you are enjoying, good.

R.

holmz , Not at all. You ever tried an analog crossover on ESLs? Wel I have, several ones and they all turned out to be awful in the end. You can do it but there are far superior ways

^Nope I have not.^

I have only tried the Vandy HPF and their sub… and it is the older one.
(not old when I got it, but it is now.)

But yes the three options are:

1. A Vandy like HPF cutting the main L/R and a sub that account for that
2. The same HPF (or a capacitor) and do the bumping up of the sub digitally using another cable from the preamp like RCAs.
3. A digital XO and the running the HPF to the main L/R and LPF to the sub(s)

In any case reducing the low frequencies to the main L/R is “always” beneficial - unless one never has low notes, DC offsets or subsonic rumble freqs.

drbond, In most cases both the HPF and the LPF built in to a high grade commercial sub would be ACTIVE filters, not the same as just inserting a capacitor in series with your main ampifier, which is a PASSIVE filter. The difference is that in an active or electronic crossover, usually there are some active gain components that correct for insertion loss (remember insertion loss from way back up this thread?). A side benefit of an active (electronic) crossover is you don’t have to be concerned too much about the input and output impedance of the driven and driving devices. In other words, you don’t have to worry about the input Z of the amplifier you are connecting to. Remember I mentioned that your amp with a 22K ohm input impedance needs about 0.1uF capacitance to roll off below 80Hz? With an active crossover set at 80Hz, you could buy a new amplifier with a very different input Z and not have to change anything. Also, you can just twist a knob to experiment with a lower or higher HPF point, if 80Hz is not satisfying. With a passive filter, you would have to re-calculate the capacitance and install the new value.

Also, your thinking about the cello frequencies as you outlined it in your post at 12:47 pm today is a bit off target. If the main speaker and subwoofer are well adjusted, then you will not hear a problem. Of course, that takes some thought and effort to get right, since as you say the cello operates right at the crossover frequencies one is most likely to use with a full range speaker + sub, 60 to 80Hz. Like everything else in life, there is no free lunch, which is why I have resisted subwoofers with my SLs even though I acknowledge the potential benefits. (I’m rethinking the issue as a result of this thread.) One point to consider is that subs are very re-sale-able, if you end up disappointed. There is a big market among home theater gurus. Finally, with a passive 6db filter, the chosen crossover point represents a frequency where the attenuation is -3db; it’s not flat down to the crossover point. Thus, another octave down is -9db, not -6db. Not so with most active crossovers.

@rauliruegas , if you listen to any modern music of course you do. It is all digitally recorded. I record other people's special records to my hard drive in 24/192. You can easily AB the recording with the original and nobody can tell the difference. In other words the full characteristics of my turntable playing a record are 100% maintained even after all this digital monkey business. It is also a lot of fun getting cool free music! 

@lewm , the problem is most commercial subs do not have any HPF. Yes, the LPF is always active. Analog crossovers add distortion and phase shifts. Some can shift phase 180 degrees with a knob but only by ear which is a trial and error nightmare. The crossover you are thinking about is too low. You should be up around 100 Hz to get the maximum benefit in terms of lowering distortion in the SLs. The problem is the subs have to be in time and phase with the SLs or you will hear them. this is true at 80 Hz also. I have listened to every crossover point and slope you can think of between 40 and 150 Hz 1 to 10th order slopes. As I have said before I can change crossovers on the fly from my listening chair. My Acoustats did better at 125 Hz. For some reason the SLs do better at 100 Hz. My guess is it is more surface area. Below that you start to loose headroom and increase distortion. Another issue is a subwoofer array for your system would be more involved than dr bond. He has 7 foot SLs with a high ceiling so below 200 Hz he is point source. You have 8 footers and if you have 8 or nine foot ceilings you are line source. In order to match the power projection of a line source speaker you have to have a line source sub array. This mean subwoofers at up to 6 foot intervals from wall to wall, corner to corner. I operate mine in stereo due to the high crossover point. Obviously, this is a more expensive set up but you are very clever and capable of building your own. 

@lewm , sorry I forgot to mention. At this moment I am using my outdated TacT 2.2X. I have a DEQX Pre 8 on order. It has a much faster processor so you do not have to worry about digital volume. When you lower volume in the digital domain you loose bits. With my Tact at low volumes you are worse than a CD about 12 bits. With the Pre 8 you are still above 24 bits. The Pre 8 also has four crossovers so I can see what a ribbon or horn tweeter will do above 12 kHz. There is the Pre 4 which is essentially the same unit as the 8 but with only one crossover for your subwoofers. You manage the units with your computer and a dedicated program. You can design any target curve equalizing the system any way you want. I keep mine dead flat until 100 hz where I increase the bass at about 3 dB.oct down to 20 Hz were I roll off steeply at 80 dB/oct creating a digital rumble filter. It also prevents launching your subwoofer cones across the room when you drop the tonearm:-)

If you look at the Stereophile review of even the old SoundLab A1, they measured the panel as flat out past 20kHz, so the need for a super tweeter escapes me. But of course ESLs do beam at HF. Depends where you sit, and your hearing acuity. Your present digital volume control would seem to be wanting in fidelity. Ok if you can run wide open.

@mijostyn  : " It is all digitally recorded.  "

For many years many of us knowed that and so what?. I can't control recording proccess. Can you?

R.

 Mijo, You wrote, "Analog crossovers add distortion and phase shifts. Some can shift phase 180 degrees with a knob but only by ear which is a trial and error nightmare."  Do you seriously believe that doing a DAC to ADC conversion, where also the signal is manipulated in the digital domain, in the signal path adds no distortion?  With the very steep filters you favor, there would be phase shift too; does your TACT enable you to correct for phase shift?  For me, phase shift is a non-issue, because with my speakers and no crossover, neither I nor anyone else can hear a 180 degree change of phase. Double-blind tested with my wife and son and other experienced listeners.  Once you add a subwoof, I suppose that phase between the main ESL and the subwoof needs to be set appropriately, but that is easy; there is just one variable.  I credit your taste in components (other than the digital ones), which makes me very curious to hear your system some day.  Maybe I'm just old-fashioned.

@lewm , any decent processor corrects phase and time. Once in numbers you can do pretty much anything without adding any distortion. It is hard for old analog guys to believe. If there is anything detrimental in the process the advantages far outweigh it. It is a new world. Some of the old ways still apply after all, our ears are analog devices. However, when it comes to processing signals to do exactly what you want, digital rules. Lew, if we were face to face I would have absolutely no problem proving that to you. 

@rauliruegas Of course not! That does not change the fact that it is digital recordings we are listening to and they are superior in many ways to older analog ones assuming they are mixed correctly and not compressed into oblivion. 

Yes you would. (Have trouble convincing me.)

I've read some comments on a subwoofer thread about how the user preferred Class A/AB amplifier for the subwoofers, as the class D truncated notes too quickly, and the like.  Consquently, currently, I'm leaning towrards favoring passive subwoofers driven by a Class A or AB amplifier(s) (which I already have).  I think I'll give Duke a call at Audiokinesis sometime soon to see what he has to offer, as I think the "swarm" can be purchased with only passive subwoofers. . . but I'll still have address LPF, HPF, etc. with that option.   

@drbond , The best bass I have heard comes from monster class A amps with exceedingly low output impedance, vanishingly low. I agree that passive subwoofers are the way to go. The problem is getting them, ones that fit your spec. AudioKinesis swarms do have outboard electronics and Duke might sell you a set without the electronics. The swarm system is a great, high value subwoofer array for people with small to intermediate size rooms and systems in the $20,000 or so price range. To play around and get used to subs and not spend to much money doing it I suppose they are fine. In the end they are not up to the quality of the rest of your system and even with four 10" woofers they are really not enough for your rather large room. My current system uses four 12" subs in a room 16 feet wide. There is no back wall as it is an open concept house. The room was designed to avoid standing waves. The system I am working on now will include eight 12" drivers in 4 enclosures. 

The best way to get passive sub is to make them. There are great kits available at Parts Express with SOTA drivers. They are as good as 90% of the commercial subs on the market and very easy to build. The only fly in the ointment is putting a fine finish on them. You can give them to a Piano restorer and they can put an excellent black finish on them. Many people cover them in equipment carpet. 

@lewm, not at all. I can AB straight analog with full bore processing by pressing a button. I have to assume you know what you are listening to and in that context it is a no brainer.  I know you don't think so which makes it more fun.