[Danny Richie]

This one is a 30Hz sine wave. Again the levels were left the same as the 20Hz level max reference. I could have turned these higher wavelengths up even more.

30Hz gave me a peak of 105 at close to 29Hz.



The other two are left again for reference.

[Danny Richie]

Here is 35Hz and 40Hz. They are starting to drop off and level out now. Again this is typical for my room. The 25Hz or so peak for my room can be seen. Not a bad place for room gain.    Even allowing for that you can easily see levels over 100db below 30Hz even at 20Hz.

35Hz hit 100db.



And 35Hz and 40Hz levels could have been higher if I would have turned them up more. I had plenty of X-max left but didn't want to overdrive the amp, and at those higher frequencies I can't judge output levels by watching the woofer move.

That reading at 20Hz of 105db was about the limit in my room. And please keep in mind that this will vary a lot from room to room. These would not hit levels like this in a huge room.

And I am sure there will be some red herring in there somewhere that someone will come up with to say this isn't valid because of blah, blah, blah... oh well. 

[rythmik]

Btw, I use Mills in my XOs, because I have found that some sand casts are not as non-inductive as purported...

AJ, but inductance is insignificant at low frequency. It is a big concern only when you go up into khz frequency.  Some amplifier even has an output inductor to achieve sufficient phase margin so that amplifier does not oscillate.  Moving that inductance to the crossover does not make a difference.

[EDIT] inductance is a still linear component. You can easily compensate that with EQ.

Is that the only reason you go with Mills?  Can it be the Mills has lower temperature coefficient and it does not produces as much distortion modulated by resistance instantaneous temperature? Or is it because the poor construction rigidity of sand cast resistors gives more micro-level vibration? 


You are asking a reason that there are all sorts of manufacturers internal know-how documents of what works and what does not. I really don't know what you want to prove here and there.

BTW, you keep mentioned this Clarity cap thing. I don't even know what it is.  But that is not a basis for generalization.
 

 

[dBe]

Dave, are you able to run the relevant section of the track through an FFT? Might be interesting to see what's actually on it...

John, see Danny's measurements below.  I was wrong on the 18Hz fundamental.  Pete must have pitch shifted it on Deeper to match the key of the song.  The original 808 drop is 18Hz.  When things get this low I can't tell a lot on the ultimate pitch.  I'm very good at nailing peaks in the mids and HF, but this one eluded me.  My bad.  What's a few Hz among frinds anyway.

Concerning Brians reply to AJ:

AJ, but inductance is insignificant at low frequency. It is a big concern only when you go up into khz frequency.  Some amplifier even has an output inductor to achieve sufficient phase margin so that amplifier does not oscillate.  Moving that inductance to the crossover does not make a difference.

Is that the only reason you go with Mills?  Can it be the Mills has lower temperature coefficient and it does not produces as much distortion modulated by resistance instaneous temperature? Or is it because the poor construction rigidity of sand cast resistors gives more micro-level vibration? 

You are asking a reason that there are all sorts of manufacturers internal documents of what works and what does not. I really don't know what you want to prove here and there.

BTW, you keep mentioned this Clarity cap thing. I don't even know what it is.  But that is not a basis for generalization.
 

 

The TCR of the Mills is very low compared to sand casts: 20ppm vs 750-800ppm. Ceramic boats don't belong in high end applications IME.

Dave

[Rclark]

AJ, but inductance is insignificant at low frequency. It is a big concern only when you go up into khz frequency.  Some amplifier even has an output inductor to achieve sufficient phase margin so that amplifier does not oscillate.  Moving that inductance to the crossover does not make a difference.

Is that the only reason you go with Mills?  Can it be the Mills has lower temperature coefficient and it does not produces as much distortion modulated by resistance instantaneous temperature? Or is it because the poor construction rigidity of sand cast resistors gives more micro-level vibration? 

You are asking a reason that there are all sorts of manufacturers internal documents of what works and what does not. I really don't know what you want to prove here and there.

BTW, you keep mentioned this Clarity cap thing. I don't even know what it is.  But that is not a basis for generalization.
 

 

Clarity Cap put resources on studying the sound of caps and why they did what they did. They spent money on it, and you were saying nobody ever would. They did this several years ago.

[THROWBACK]

Brian says: "Some describe slam as "mid bass slam". It is a result of peak around 70hz to 120hz.  On our PEQ control, turn it on, set the frequency to 80hz, bandwidth to mid, and gain to 3db.  If that gives you the right direction, you just need more of that with other EQ.  Our hearing is very insensitive to the bottom end. So the more obvious effect is either the higher order harmonic distortion or FR emphasis in midbass region.  SRS lab has a patent on how to make small subs sound big. The trick is intentionally inject distortion to the system.

Another direction to look for is the phase alignment.  Do 3 plots: one with front speakers only, one with subwoofer only, and one with both turn on. Tabulate the response give you better pics.  Maybe your room as a room mode peak at the crossover point and that masks the effect that the sub and front speakers are phase misaligned. 

In terms of bigger amp for SW12-16, our kits are designed as a whole, meaning we know how much power the driver can take without destroying them.  If we pick A370 for a particular kit, that means that power has almost maximimze the excursion utilization. Going to the next level power can spell trouble."

Thanks, Brian. I'll try it. But I believe I need 2 controls in the PEQ: One to notch out a boost at 30Hz; the other  to boost the 80Hz region.




[/quote]

[dBe]

Thanks, Brian. I'll try it. But I believe I need 2 controls in the PEQ: One to notch out a boost at 30Hz; the other  to boost the 80Hz region.

The (in)famous LS3/5A had a 3-4dB peak at cabinet resonance (105Hz) to give the illusion of more bass.

http://www.g4dcv.co.uk/ls35a/history.html

In the studio we recognize 60-80Hz to be a "mud range" that causes a lot of masking, but the range from 80-110Hz males bass sound punchier without adding too much chestiness to recordings.  Also, rooms with an 8' ceiling height have a pretty big bump at 71 hz to begin with.  This could be partially responsible for you not really picking up on the 'smack' of a kick drum for example.

Dave

Dave

[rythmik]

Thanks, Brian. I'll try it. But I believe I need 2 controls in the PEQ: One to notch out a boost at 30Hz; the other  to boost the 80Hz region.

First try it with 80hz boost.

[dBe]

The (in)famous LS3/5A had a 3-4dB peak at cabinet resonance (105Hz) to give the illusion of more bass.

http://www.g4dcv.co.uk/ls35a/history.html

In the studio we recognize 60-80Hz to be a "mud range" that causes a lot of masking, but the range from 80-110Hz makes bass sound punchier without adding too much chestiness to recordings.  Also, rooms with an 8' ceiling height have a pretty big bump at 71 hz to begin with.  This could be partially responsible for you not really picking up on the 'smack' of a kick drum for example.

Dave

Dave

[AJinFLA]

AJ, but inductance is insignificant at low frequency.

Correct. So, again, what is your explanation for "drier" sound in your subwoofer using Mills vs sandcast in the sensing coil circuit?

Is that the only reason you go with Mills?

No, I like their Quantum filtering effect too.

Can it be the Mills has lower temperature coefficient and it does not produces as much distortion modulated by resistance instantaneous temperature? Or is it because the poor construction rigidity of sand cast resistors gives more micro-level vibration?

Sure, could be a myriad of reasons like that, including Quantum purification and other esoterica. I haven't really investigate those cutting edge frontiers that have zero audibility evidence. Been too busy over the last 10 years making probably in excess of 60 gradient type systems, dipoles, cardioids, monopoles and variations of each and testing them, sometimes in multiples in dozens upon dozens of rooms. I know, I know, silly me, mired in the really real world measurable in soundwaves>cochlea stuff.

You are asking a reason that there are all sorts of manufacturers internal documents of what works and what does not. I really don't know what you want to prove here and there.

Eh?
I was asking about evidence (of the scientific variety becoming of a PhD EE) for resistor-in-servo-loop sound. It piqued my curiosity. If your evidence is "I heard it, I said so", then fine. We'll leave it at that. No harm no foul.

BTW, you keep mentioned this Clarity cap thing. I don't even know what it is.  But that is not a basis for generalization.

It's another dead end that debunked your earlier statement, but Cap "discussions" never end well, so perhaps we could stick to dipoles, bass...heck, even Maggies.

cheers,

AJ

[scorpion]

I really don't know if I should write here but I think I may contribute 'objectively' regarding the Bass power of the SW12-16FR as featured in Danny's V speakers and as discussed here.
Danny has given all data about the speakers and also over his H-woofers so putting these inside MJK's MathCad simulation program is no problem. Then what is the output.
Given one H with two parallel SW12-16FR units and given Danny's own speaker drawings the 1m (40") distance and 80 cm (32") ear height and 1 watt input to the woofers would yield this response:



Now extrapolating this to 100 db at 30 Hz gives this chart:



This frequency response and in the figure above is given by applying a 125 Hz 2nd order L-R crossover and you see that the effective crossover frequency is somewhere near 300 Hz really. This is how it works using the crossover to linearize and utilize the quarterwave response peak to augment crossover frequency. Look how impressively linear the response is from 30 Hz to about 250 Hz.

However MJK also give indications for cone displacement. This is an RMS measure so at least multiply with SQR(2) = 1.414, but MJK himself says this simulation probably is not so precise.
So I would not really dispute the 20 Hz claim but I certainly would support the 30 Hz claim for 100 dB SPL given what I stated above for distance and ear height. Now this is for one speaker only, a pair will
certainly better the picture. This is the displacement figure:



/Erling 

[Davey]

When I plug the SW-12-16 numbers into a different spreadsheet I get (essentially) the same numbers as Erling.

At Xmax (18mm), free-space SPL at 1 meter is 93db at 20Hz and 98db at 30Hz.
A dipole configuration (I assumed D=300mm...I'm not sure if that's correct) yields 74db at 20Hz and 82db at 30Hz.

That's a single driver of course.  Add 6db for a second driver and another 6db for four drivers.

This is a pretty simple calculation.  Any measured numbers greater indicate either room/boundary gain, measurement error, or drive past Xmax.  Or a combination of those.

Cheers,

Dave.

 

[JohnR]

I got 112 dB for four drivers... I better check that.

Minus dipole concellation, minus distance, plus room effects. However, there is also the dipole proximity effect whereby the dipole loss is not as great at finite distance as it is at infinity - http://musicanddesign.com/Dipole-axis.html and http://www.hifizine.com/2012/03/on-dipole-subwoofer-placement/ .

[Davey]

I will recheck mine also.

Danny lists Sd of that driver at 490 cm2.  I question that but gave him the benefit of the doubt in the calculation.
Looking at the surround on the GR driver, I don't see how Sd could be larger relative to other 12" drivers which have a smaller surround.

Cheers,

Dave.

 

[Danny Richie]

Danny lists Sd of that driver at 490 cm2.  I question that but gave him the benefit of the doubt in the calculation.

I get 490.87 sq cm or 24.99 cm in diameter. That is only 9.8" across from the center of the surround to the center of the surround. That is actually on the low side for a 12" woofer.

[Davey]

The photograph makes it look the driver has a very wide surround.
Measuring from middle of surround to middle of surround would yield a fairly optimistic number....IMO.

Do you agree with numbers posted by myself and Erling?

Cheers,

Dave.

[dBe]

The photograph makes it look the driver has a very wide surround.
Measuring from middle of surround to middle of surround would yield a fairly optimistic number....IMO.

Do you agree with numbers posted by myself and Erling?

Cheers,

Dave.

That is the industry standard for measurement.  Center of surround to center of surround.  Make no sense at all to me, but that is the way it has been measured since the mid 70's.  Vance Dickason established the standard and it has been in place ever since.

Dave

[Danny Richie]

That is the industry standard for measurement.  Center of surround to center of surround.  Make no sense at all to me, but that is the way it has been measured since the mid 70's.  Vance Dickason established the standard and it has been in place ever since.

Dave

Yep, that has always been industry standard. The surround is part of the moving surface.

And actually a larger cone with a smaller surround has more moving surface area than a small cone with a large surround.

[Davey]

Yep, I'm aware of the industry standard.
But these days we're surrounded (another little pun there) with drivers that have very large surrounds relative to the driver size.  This introduces an error if measuring with the traditional method.
Some of the manufacturers have adjusted for this and now measure cone width plus just one half of the surround width.

Cheers,

Dave.

[dBe]

Yep, I'm aware of the industry standard.
But these days we're surrounded (another little pun there) with drivers that have very large surrounds relative to the driver size.  This introduces an error if measuring with the traditional method.
Some of the manufacturers have adjusted for this and now measure cone width plus just one half of the surround width.

Cheers,

Dave.

Uhm. Danny.  That is what I meant by center to center of the surround width.  That is the old woodworker in me talking.  Same thing.

Dave