"Fast" woofers.

[audiojack]

This is covering this topic pretty well:
https://www.audiosciencereview.com/forum/index.php?threads/step-response-question.15375/

the tldr version:
1cm measurements about my SVS SB-1000 and my DIY sub based on Dayton Audio RSS315-HF-4 (both are sealed boxes and 12")

SVS:
View attachment 124286

Dayton DIY:
View attachment 124287

As you can see there is a dramatic difference in the fall time meaning that the Dayton comes to a rest way faster than the SVS
So there can indeed be huge differences between speakers when it comes to 'speed' (which is not speed but transient response really)

Hey! What are the (inner and/or outer) dimensions of the sealed box for the 12" Dayton Audio RSS315-HF-4 ? How low does it get? Did you use bracing and polyfill?
Which amplifier do you use for the Dayton subwoofer? Thank you.

I'm considering making a Dayton subwoofer either a 10" or 12" with the Dayton SPA 300-D plate amplifier.

 

[ppataki]

Hey! What are the (inner and/or outer) dimensions of the sealed box for the 12" Dayton Audio RSS315-HF-4 ? How low does it get? Did you use bracing and polyfill?
Which amplifier do you use for the Dayton subwoofer? Thank you.

I'm considering making a Dayton subwoofer either a 10" or 12" with the Dayton SPA 300-D plate amplifier.

I sold that gear more than 4 years ago so I am not sure I can answer all the questions correctly but I will give it a try:

- outer dimensions were 35x35x35 cm, cabinet was made of 18 mm MDF
- sealed boxes can go down to 0Hz theoretically, you can read about it here. But in real-life it will depend on the room and the positioning of the speakers and your MLP in the room. Mine went down to 23Hz at -3dB. You can use REW's Room Sim component to see how they will perform in your room/positioning. You can EQ sealed boxes very well, so ultimately you will be limited by the speaker's xmax and the output power of your amp 'only'
- I did not use any bracing and I did fill the boxes with polyfill completely. Nowadays I use vibrodamping sheets, felt and melamine foam and if bracing is needed I use this technique
- I used a Hypex NC250MP amp to drive the subs (250W each) - I don't like plate amps so I always use 'external' amplification

I would highly recommend considering a dual opposed subwoofer (DOS) concept - that way you eliminate vibration completely and you double the cone surface area
You can check my builds here on ASR if you filter on my username in the DIY section

Good luck!

 

[mhardy6647]

... speaking of woofers and fastness... there are a couple of other important parameters, of course.

 

[witwald]

What are the (inner and/or outer) dimensions of the sealed box for the 12" Dayton Audio RSS315-HF-4 ? How low does it get?

With an enclosure volume of 72.5 litres, the RSS315-HF-4 can produce the following results when tuned to a Qtc = 0.707. In this simulation, I have added a 4th-order Linkwitz–Riley low-pass filter with a nominal cut-off frequency of 70Hz. This produces an acoustic −6dB point of approximately 80Hz, in keeping with a THX-style crossover frequency between the subwoofer and the main speakers. In this configuration, the subwoofer has a −3dB low-frequency cut-off point of 26.7Hz. With the amplifier running at 100W referenced to 8 ohms, we are just going to exceed the driver's Xmax below about 25Hz or so. The maximum SPL produced by the subwoofer at this input power level is around 105dB (anechoic). Note that neither this figure, nor the frequency response curves, take into account any effects of room boundary reinforcement or room gain.

If we increase the enclosure volume to Vb = 195 litres, we can expect the following results. The subwoofer has a −3dB low-frequency cut-off point of 24.1Hz, which is marginally lower than before.

 

[witwald]

I'm considering making a Dayton subwoofer either a 10" or 12" with the Dayton SPA 300-D plate amplifier.

The SPA 300-D won't allow for any EQ or additional filtering, and the phase adjustment is limited to a polarity switch. If your budget permits, then the Dayton Audio SPA500DSP 500W Subwoofer Plate Amplifier with DSP would be a much more flexible choice for use with the 12" Dayton Audio RSS315-HF-4. Apart from its EQ and filtering options, it will likely have the facility for some delay adjustment to enable a better blending in with the main speakers.

For example, with a sealed enclosure of Vb = 72.5 litres, a 2nd-order high-pass peaking filter set to 20.5Hz and Q=2.0 would produce the following response. Here we now obtain a −3dB low-frequency cut-off point of 20.0Hz due to the low-frequency alignment being filter-assisted. The maximum SPL comes in at 100.5dB for a nominal input power of 20W re 8Ω, while not exceeding Xmax anywhere in the frequency range. The maximum power going into the speaker is at about 20Hz, and comes to a quite low value of 70W. The unassisted low-frequency alignment has a noticeably higher −3dB low-frequency cut-off point of 24.1Hz.

If it is desired to maintain the second-order natural roll-off rate of an unassisted sealed enclosure, then we can apply some parametric EQ (with a DSP capable amplifier) to get a somewhat flatter and more extended bass response.

Once again using the sealed enclosure with Vb = 72.5 litres, we can apply a parametric EQ of +6dB at 21 Hz with Q=2.0 to achieve the results shown below. Note that the −3dB low-frequency cut-off point is now 18.9Hz, while still achieving 99.5dB maximum SPL without exceeding Xmax.

If we dial back some of the boost and increase the frequency at which the EQ is applied, we can get the following result. Here the applied parametric EQ is +5dB at 22.5 Hz with Q=2.0, and the −3dB low-frequency cut-off point is now a still respectably-low 20.3Hz, while achieving 100.7dB maximum SPL without exceeding Xmax.

 

[witwald]

Another option that could be worth considering for the 12" Dayton Audio RSS315-HF-4 is placing a large bipolar capacitor in series with the woofer driver.

For example, using the sealed enclosure of Vb = 72.5 litres, after placing a capacitor in series with the woofer with a value Cs = 1800 μF, we get the following response. The subwoofer has a third-order roll-off rate at low frequencies. Here we have obtained a −3dB low-frequency cut-off point of f3 = 19.4Hz, and a maximum SPL of about 100dB for an input power setting of 41.0W re 8Ω, without exceeding Xmax. For this power level, it is seen that the driver reaches Xmax at 20Hz, and the peak in the power dissipation curve occurs just below this frequency.

 

[witwald]

The Dayton Audio SPA500DSP 500W Subwoofer Plate Amplifier with DSP is a little bit limited in the types of high-pass filtering that it can provide. It allows for what appear to be 2nd-order and 4th-order Butterworth high-pass filters only. There is no 2nd-order peaking filter available to provide the option of a traditional filter-assisted bass-reflex or closed-box low-frequency alignment. However, there is a workaround to this problem.

To produce behaviour that is equivalent to a 2nd-order high-pass peaking filter, all we need to do is combine a 2nd-order high-pass filter (HPF) with a suitable parametric EQ (PEQ). The tuning frequency for the HPF and the PEQ must match. Then, if 6.0dB of peaking is needed with a Q=2.0, then we need to apply 9.0dB of PEQ with a Q of 2.0.

In an earlier example, we studied a sealed enclosure of Vb = 72.5 litres that used a 2nd-order high-pass peaking filter set to 20.5Hz and Q=2.0, which produced a −3dB low-frequency cut-off point of 20.0Hz. If we now replace this peaking filter with a 2nd-order Butterworth HPF set to 20.5Hz and a PEQ set to 20.5Hz with +9.0dB boost with a Q=2.0, then we obtain the following results. Here it is seen that the frequency response curve matches the earlier result.

 

[witwald]

The Dayton Audio SPA500DSP 500W Subwoofer Plate Amplifier with DSP is a little bit limited in the types of low-pass filtering that it can provide. It allows for what appear to be 2nd-order and 4th-order Butterworth low-pass filters only. There is no provision for 2nd-order or 4th-order Linkwitz–Riley filters. However, there is a workaround to this problem.

To produce a filter response that approximates a 4th-order low-pass Linkwitz–Riley filter, all we need to do is combine a 4th-order Butterworth low-pass filter (LPF) with a suitable parametric EQ (PEQ). The tuning frequency for the LPF and the PEQ should match. The PEQ that needs to be used should introduce a cut of 3dB and have a Q=1.5.

In an earlier example, we studied a sealed enclosure of Vb = 72.5 litres that used a 4th-order Linkwitz-Riley low-pass filter set to 70Hz, which produced an acoustic −6dB high-frequency cut-off point of about 80Hz. If we now replace the Linkwitz–Riley filter with a 4th-order Butterworth LPF set to 70Hz and a PEQ set to 70Hz with a cut of 3.0dB and with a Q=1.5, then we obtain the following results. Here it is seen that the frequency response curve matches the earlier result quite closely. As we are dealing with a minimum-phase system, matching the magnitude response curve should result in a good match with the phase response curve as well.

 

[audiojack]

The Dayton Audio SPA500DSP 500W Subwoofer Plate Amplifier with DSP is a little bit limited in the types of low-pass filtering that it can provide. It allows for what appear to be 2nd-order and 4th-order Butterworth low-pass filters only. There is no provision for 2nd-order or 4th-order Linkwitz–Riley filters. However, there is a workaround to this problem.

To produce a filter response that approximates a 4th-order low-pass Linkwitz–Riley filter, all we need to do is combine a 4th-order Butterworth low-pass filter (LPF) with a suitable parametric EQ (PEQ). The tuning frequency for the LPF and the PEQ should match. The PEQ that needs to be used should introduce a cut of 3dB and have a Q=1.5.

In an earlier example, we studied a sealed enclosure of Vb = 72.5 litres that used a 4th-order Linkwitz-Riley low-pass filter set to 70Hz, which produced an acoustic −6dB high-frequency cut-off point of about 80Hz. If we now replace the Linkwitz–Riley filter with a 4th-order Butterworth LPF set to 70Hz and a PEQ set to 70Hz with a cut of 3.0dB and with a Q=1.5, then we obtain the following results. Here it is seen that the frequency response curve matches the earlier result quite closely. As we are dealing with a minimum-phase system, matching the magnitude response curve should result in a good match with the phase response curve as well.

View attachment 405140

Thank you @witwald for the detailed information. I have zero experience with parametric eq and measuring microphones. What is the software from the screenshots? Hornresp? Are these calculations or also mic measurements?
This is maybe a noob question, would the Topping d50 iii with parametric eq and subwoofers connected via the rca outputs and main speakers on the xlr give a similar results in terms of subwoofer parametric eq? Main speaker delay and such are not possible on the d50 iii I guess.

Another nood question, could the Dayton Audio RSS315-HF-4 be powered by the Dayton Audio SPA250DSP 250 watt amp? Or 2x Dayton Audio RSS315-HF-4 on one Dayton Audio SPA500DSP 500 watt amp, so each gets 250 watt? Or is that seriously under powered? I don't listen on high volumes.
Thank you.

 

[witwald]

The software that was used for the simulations was VituixCAD. No measurements were done.

The parametric EQ on the Topping D50 III is limited to only the USB input. The D50 III also has no provision for any low-pass or high-pass filters. Neither was there any provision for a delay function of any sort.

The Dayton Audio SPA250DSP is rated as a 250 watt amplifier into 4ohms. It should be adequate for your purposes. All of the simulations show that Xmax of the Dayton Audio RSS315-HF-4 is reached with 80W or 100W of power input, depending on whether the closed-box alignments are filter assisted (80W) or not (100W).

I've redone a previous simulation, this time referencing the power to 4ohms to match the specification of the Dayton Audio amplifier. There is 5.0dB of PEQ at 22.5Hz with a Q of 2.0, and a 72Hz 4th-order low-pass Linkwitz–Riley filter is included. The results are shown below.

It's apparent that Xmax is reached at 21.5Hz for a nominal input power of 55W into 4ohms. In this configuration, the subwoofer has a maximum output level of 101dB with that input power. The 250W amplifier would seem to have plenty of headroom, as Xmax is achieved well before the 250W maximum rating is reached.

 

[audiojack]

This is covering this topic pretty well:
https://www.audiosciencereview.com/forum/index.php?threads/step-response-question.15375/

the tldr version:
1cm measurements about my SVS SB-1000 and my DIY sub based on Dayton Audio RSS315-HF-4 (both are sealed boxes and 12")

SVS:
View attachment 124286

Dayton DIY:
View attachment 124287

As you can see there is a dramatic difference in the fall time meaning that the Dayton comes to a rest way faster than the SVS
So there can indeed be huge differences between speakers when it comes to 'speed' (which is not speed but transient response really)

How many Hz was the test tone that you used? Or am I misreading the graph?

 

[ppataki]

How many Hz was the test tone that you used? Or am I misreading the graph?

It was a sweep measurement in REW (0-200Hz)

What you see on that graph is a Wavelet diagram in REW. I usually use it with these settings:

It shows you how the low frequencies are delayed compared to the rest of the spectrum (basically post-ringing and pre-ringing as well)

 

[audiojack]

It was a sweep measurement in REW (0-200Hz)

What you see on that graph is a Wavelet diagram in REW. I usually use it with these settings:

View attachment 409858

It shows you how the low frequencies are delayed compared to the rest of the spectrum (basically post-ringing and pre-ringing as well)

Thank you it's more clear now. So the upper graph is the sweep and the lower graph is at 30Hz?

 

[ppataki]

Thank you it's more clear now. So the upper graph is the sweep and the lower graph is at 30Hz?

You mean the two graphs in this post?

Those are both the result of a sweep from 0 to 200Hz

 

[audiojack]

You mean the two graphs in this post?

Those are both the result of a sweep from 0 to 200Hz

To me it seems like the lower graph is the representation of the upper graph at 30 Hz, they match.

 

[ppataki]

To me it seems like the lower graph is the representation of the upper graph at 30 Hz, they match.

I repeat once more (for the last time):
I took two sweep measurements, both 0-200Hz, one for the SVS sub and the other for the Dayton sub and you see the Wavelet display of those measurements there