Subwoofers with servo

Mr TAD

New Member
Aug 6, 2017
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#21
Here is the thread where I learned about Rythmik and about direct servo, if you are interested in reading it... http://www.whatsbestforum.com/showt...al-fast-and-accurate-subwoofer-you-have-heard
Thanks for the link, Tom. Very interesting discussion.

I believe that yours and mine quest for the perfect subwoofer might be similar. I too was looking for a sealed subwoofer, preferably with built-in filters. When I heard the Velodyne DD+ series, I was instantly sold on the tightness, dry punch and musicality.

Having heard and now using a DD+10 myself, it has really raised my expectations of how a trimmed subwoofer system should sound and performed.

I've visited a couple of pretty well-built home cinemas, and one very well-built cinema, and listening to the low-end performance in each cinema, all I could think of was "why didn't they go for the Velodyne subwoofer sound?". But that's my taste and it can of course differ from somebody else's taste.

Personally, the DD+10 was the best candidate for my room, because I wanted the fastest of them and figured that the smallest model would give me that. It still pack a lot of power, and I'm not close to using it all - except when listening to a DSD recording of a church organ playing one of its longest pipes. :)

I'm also using the JL CR-1 outboard crossover system as well. Honestly, the only other subs I've had in my system were Wilson, Focal and Velodyne.
I was looking at the JL CR-1, but ended up getting a Bryston 10B Sub active subwoofer filter. Really looking forward to integrating it in my system. No shadow over the mastering-grade Crookwood C1 controller I'm using now for bass management, it sounds great. But swapping it out to the Bryston will practically remove all the remaining ICs in the signal-path, and that's one of my goals. The Bryston filter will enable me to do tweaks while listening to the result, which the Crookwood wouldn't allow me to do - swapping resistors to change the crossover frequency etcetera.

Ah well, the Bryston will hopefully show up next week.


Cheers
Fred
 

Mr TAD

New Member
Aug 6, 2017
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#22
Personally, if this Velodyne goes down and is not reparable...i think JL and Paradigm are the 2 subs i would consider.
The Paradigm Signature Sub 2 and Persona Sub looks really interesting.

I'm going to try and audition one of them.


Thanks for the tip

Fred
 

Mr TAD

New Member
Aug 6, 2017
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#23
BTW, I installed the Bryston 10B sub active crossover. Man, it's a wonderfully sounding box. I'm so glad I opted for an analogue solution.

With the Crane Song Solaris DAC -> Bryston filter -> Velodyne DD+10, it really makes me respect the Velodyne sub even more. Now, the sub low-end is thunderous in my control room - fast, earthy and punchy.

It's interesting listening to records where even the mastering engineer missed the excessive sub low-end energy still present in the recording.

Interestingly enough, filtering out the low-end with one of the most transparent crossover filters on the market, made the sound stage open up a bit - the mid-range depth got even deeper, even more immersive, and the stereo panorama integrity further improved, beyond what the speakers by themselves can portray in my room. Which tells me that my ATC P1 amp will be exchanged for something even better in the future.

For now, I'm super happy with my setup, and I haven't even tweaked the filter settings in the Velodyne to accommodate the new crossover frequency.


Cheers
Fred
 

LL21

Well-Known Member
Dec 26, 2010
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#24
That is interesting. So instead of sending the full signal to the sub...you are now sending ONLY the low end element of the signal. And NOTHING else has changed with your sub settings? And this has made that much difference? Very interesting. Thanks for sharing this.

ALSO - ARE YOU RUNNING YOUR MAIN SPEAKERS DIFFERENTLY WITH/WITHOUT THE BRYSTON? Are you driving your main speakers full range or also cutting them off using the Bryston?
 

Mr TAD

New Member
Aug 6, 2017
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#25
That is interesting. So instead of sending the full signal to the sub...you are now sending ONLY the low end element of the signal. And NOTHING else has changed with your sub settings?
The signals have been filtered all along, before the crossover frequency was set to 85Hz - 24dB/octave - in my Crookwood C1 monitor controller. I couldn't adjust the crossover without having to open the unit and change resistors. The low-end was sent to the woofer and the rest of the spectrum to the speakers.

With the Bryston filter I was able to raise the crossover to 100Hz, and I needed to do that due to the quarter-wave phase cancellations that all book-shelf speakers produce when positioned on speaker stands. No shadow over the TAD CE-1 speakers, they are literately ruler flat down to about 30Hz, my problem was with the acoustics and the only way around it was to incorporate a subwoofer - radiating the low-end from another position in the room, problem gone.

The highest filter slope in the Bryston is 18dB/octave, so a little bit more crossing of the frequency bands compared to the Crookwood C1.

I didn't change any filter settings in the Velodyne, yet.

And this has made that much difference? Very interesting. Thanks for sharing this.
Indeed it did! :)

The increased clarity, I believe, is due to the super high-quality Bryston filter, especially compared to the filter I was using before, which had opamps and maybe even caps in the signal-path. The Bryston is super clean, super clean. Certainly putting through sub low-end deeper and more dynamic than my previous filter.

ALSO - ARE YOU RUNNING YOUR MAIN SPEAKERS DIFFERENTLY WITH/WITHOUT THE BRYSTON? Are you driving your main speakers full range or also cutting them off using the Bryston?
In a small room like my control room, I think it counteractive to let the speakers play full-range and have the low-end from both the speakers and the subwoofer mix together. Especially with the natural phase-cancellation due to the position of the speakers. Also, unloading the two lowest octaves from the speakers, can increase the dynamics of the upper bass and even open up the whole sound stage a little bit, as in my case.

I'm missing out on the possible stereo information below 100Hz, because I only have one Velodyne subwoofer, but I don't mind, incorporating a subwoofer helped solving an otherwise unsolvable acoustic problem.

On the other hand, in a larger room and with larger speakers, it's possible to get a very musical result by letting the floor speakers play full-range and just use the subwoofer to extend the reach of the low-end, and the dynamics, and find the perfect spot for the sub low-end to radiate from.

That's what you're doing with your subwoofer, right? Having large Wilson speakers.

My living room setup consists of a pair of ATC SCM12 Pro book-shelf speakers and my old subwoofer, and in that setup I let the speakers play full-range, and get some low-end support from the subwoofer (which plays to about 60-70Hz). But they are sealed speakers so there's no bass port frequency bump and they roll-off at 12dB/octave, so it works just fine to mix the low-end of both the speakers and the subwoofer.

If you get the chance to try a really good crossover filter like the Bryston, it would be interesting to hear your thought about sending the low-end to the Velodyne and the rest to the speakers. I mean, both the amp and the woofers of the speakers would have less strain, especially at higher listening levels. And you would be able to control where the sub low-end radiates from. On the other hand, you would add filtering to you main speakers, and often, you get a smoother low-end in different listening positions, but letting the low-end radiate from several positions (though they phase-cancel at some positions).


Cheers
Fred
 

LL21

Well-Known Member
Dec 26, 2010
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#26
Very interesting!! Thanks for that...a lot of work to get that set up right. I applaud your commitment.
 

Mr TAD

New Member
Aug 6, 2017
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#27
Very interesting!! Thanks for that...a lot of work to get that set up right. I applaud your commitment.
It's a never ending story... :)

Tomorrow I'm going to properly calibrate the subwoofer with Room EQ Wizard and a Brüel & Kjaer measurement microphone. And then adjust the low-end by ear of course.

Thanks for your kind words and the tip about the JL and Paradigm subwoofers.

I must say that the Paradigm speakers and subwoofers look very interesting.


Cheers
Fred
 

LL21

Well-Known Member
Dec 26, 2010
10,929
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#28
Great...let us know how the calibration goes! As for Paradigm...I have been told you really need to power that thing properly or it will 'choke'. If you can fully power it with all the juice it requires...it is apparently pretty awesome and the main place you're going to go up from there is something like the Wilson Thor (so i am told).

However, if you cannot, the Velodyne DD18+ apparently is the way to go...particularly when you can buy 2 of them for the price of 1 Paradigm Sub 2.
 
Jul 2, 2015
616
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#29
I can attest to the ability of multiple DD18+ ;)
I've never heard bass like it, and more musical than the Sub2 that i tried
 

LL21

Well-Known Member
Dec 26, 2010
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#30
I can attest to the ability of multiple DD18+ ;)
I've never heard bass like it, and more musical than the Sub2 that i tried
Wow...good to know. You always hear about the legendary Sub2, JL Gotham and Magico QSub (perhaps the descendant of the mighty Krell Master Reference Sub). But it is nice to hear about experienced people who have worked with multi-sub successfully with DD18+...i do know they have set up the Velodyne's to be daisy chained. I presume this is what you did? So it is all controlled by one? Or do you actually set each sub up separately?

Very curious to learn!
 
Jul 2, 2015
616
15
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#31
It is all controlled from one master sub, but iirc the subs have been eq'd individually.
So i point the podger at the top left sub and all four respond, or i twist the frequency or volume knobs on the top left and all four respond.
It did take a few attempts to get right, with help from the UK velodyne rep. Requires an R232 connection to all.

Then when we had them all talking to each other the Velodyne guy set about redoing the eq.

I found that the auto tune process encourages you to locate the subs in the optimal position to fully load the room with the least volume setting. In theory that sounds like a good idea, but in practice the bass overpowers the experience when done this way.
For example, i left things running to run the subs in and took the dogs out with a friend.
As we returned we could hear my system from about a mile away, with all the windows closed.
My friend asked what volume they were running at, i replied 7 and he seemed satisfied.
Out of....?
70
��

So the autotune process wanted us to locate the subs in a way that made the most impact with the least volume.
But i suggested, how about putting them in a null point?
We had so much power that we could over power the null, and we might get more control.
Also, after a few weeks living with them in off axis locations, i had formed my own conclusions about the whole
'Bass is non directional' theory of subwoofer placement, in that its a load of bollocks.
Even rolling them in below 40hz i could clearly feel that the bass was coming from a different location and moving in a different direction to the signal ftom the main speakers, leading to an uncohesive experience.
So i insisted that we place the subs on the same axis as the main speakers, and now we started to get somewhere.
The Velodyne rep was a tad easily flustered so i took the dogs out and left him to it.
When i came back he was feeling pleased, although the subs were now inside the main speakers. He and Nick, the guy who sold me the subs had had a move around to see if they could improve things, found they could make no improvements and forgotten whether the subs were to go inside or outside of the mains.
The improvement in the bass was so profound that we left things there.

But over the following weeks i grew to dislike having the subs inside the main speakers, it sounded like the main speakers were trying to sing through a wall of bass that reached you first.
So i took it on myself to shift them around, but didnt touch the eq or setup. And now we were really getting somewhere.
Over the following months i tried inching the stacks around to get the best time alignment, and just recently i have inched the stacks away from the mains and out towards the side walls, this has given a big improvement with lots more space and detail coming from the main speakers
I'm really happy with where we are at.
I do envision another pair to go atop the stacks, and possibly another one off axis in the corner behind the listening position to maybe smooth things out a little - there is some variance in different parts of the room, but it basically goes from fantastic to monstrous :D
 

LL21

Well-Known Member
Dec 26, 2010
10,929
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#32
Great stuff!!! One sub is tricky...particularly when it will clearly not solve certain issues. But 2 comes with its own set of complications even if the solution is ultimately a better one for the most part. 4 must be amazing when right and torture when not. Congrats on getting it right and continuing to fine tune from there.

"from Fantastic to MONSTROUS." Love how that sounds!
 

Bruce B

WBF Founding Member, Pro Audio Production Member
Apr 26, 2010
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Seattle, WA
www.pugetsoundstudios.com
#33
BTW, I installed the Bryston 10B sub active crossover. Man, it's a wonderfully sounding box. I'm so glad I opted for an analogue solution.

Cheers
Fred
The thing I love about the JL crossover is that the crossover freq. going to your main rig is more flexible. There are 2 sets of filters and controls, one going to the subs and the other to the mains.
 

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