Don't try too hard to bring back 1960's Vox Supreme style speaker stands?
Call the bellhop...
Well.... in other news.... I have 2 working drivers installed and took another indoor measurement at 16"
Most of this work has been to appease my peers, not that I am not doing it for myself, as it is myself who want to appease you. I'm sure @gedlee can find some things to point out... I am interested in hearing them. One day I will make it out doors for a measurement but for now this is what I have. There is no damping material used in the slot or inside the box yet. This is the 15" driver PPRSL as I've dubbed it. I think I can improve the FR more, yet but this is a good start considering the challenges of slot loaded woofers.
It's disappointing to see an education the forum has given squandered for a machine that isn't telling fact from fiction.
But to presume to educate us via this machine is simply insulting.
In what universe is a response of +/- 10dB from 200 to 600Hz a "good start"?
Why did you decide to ruin the midrange response of the two 15" by putting them in a slot ?
A quote is a quote, but it will definitely be worth noting when a quote is derived from AI.... in DeepSeeks defense, I do not normally use it nor was it prompted which should expectedly lower the quality of the experience... I didn't expect it to make up fake quotes from AES, sorry... I wouldn't say that foul play was had on my side... the AI did apologize if that makes you feel any better.
I don't think that my education has been "spoiled" by AI, all it has done is cause me to have more questions so as long as I seek validation from real professional, as I've done here in this thread for years now, it should work out.
We have not touched on the topics of Damping Force and Damping Factor in this thread. I try to at least do some type of research before I come to the thread. I have a better understanding of Back Emf now thanks to AI.
The rest of the AI generated content has been designated as such.
I wouldn't wait to see a question mark to correct erroneous statement.
I don't think that my education has been "spoiled" by AI, all it has done is cause me to have more questions so as long as I seek validation from real professional, as I've done here in this thread for years now, it should work out.
We have not touched on the topics of Damping Force and Damping Factor in this thread. I try to at least do some type of research before I come to the thread. I have a better understanding of Back Emf now thanks to AI.
The rest of the AI generated content has been designated as such.
I wouldn't wait to see a question mark to correct erroneous statement.
It makes me feel that there is little understanding of the nature of AI...
In the past you've indicated that posting incorrect statements is effective at eliciting responses. This confrontational style is already a source of consternation.
In this age of AI it takes on new meaning and greater consequences.
Well first of all, the response drops -10db from 200 to 600 hertz.... and, its a smooth transition at that. I don't think there is anything here that would have trouble being sculpted by EQ, unlike the sharp null in the response of the first slot design. Considering the xover will never be over 300hz I think it is something to work with. Lets keep it in context by the way. I haven't seen a slot loaded woofer with a response better than this. There no large peaks/nulls that stop one from sculpting the response
Looking at response of the first slot design, I'd say I did good. Those nulls did not help anything, so as long as the 18" PPRSL plays as nice as the 15", I'll be happy.
I was using DeepSeek to cross reference Grok. Grok was making some silly mistakes i'm using another AI to cross reference it usually creates argument they both go back-and-forth... hopefully catching each other's silly mistakes. At the end of the day, I personally would only consider it a tool to lead to more questions to be verified by more legitimate sources.
agreed. Fortunately the mainstay of information has been covered already. I went off into an AI bing on resistance versus wiring topology. I think I landed on solid ground.... no?
Damping Factor offsets the lack of back emf power had due to higher resistant topology.
I think I see where you're coming from and unless I'm mistaken, I'd disagree with your conclusion.
Are you familiar with the Miller effect? Your AI model might not be able to make the connection I'm implying here, but someone who understands the connection between an impedance and how you approach acting upon it, might.
Well The miller effect is a new concept for me... I'll research it. What I think I know is that a drivers Back Emf is a figure that we can look at as voltage generated by movement. The voltage generated is separate from the circuits resistance. As resistance increases (series wiring for example) the voltage results in less power, the damping factor is higher for higher resistance topology in order to counter act this, and retain a uniform damping character across different levels power of back emf due to the influence of resistance.
If thats not how it works then maybe someone can elaborate on how it truly works...
Otherwise AI isnt shy;
At 11:05 PM EDT, Saturday, July 05, 2025, the Miller effect plays a nuanced role in damping for your four Acoustic Elegance 18H+ and NMB 600 woofers (32Ω series load, adjusted 88.5 dB/1W/1m at 30 Hz) driven by a Crown CTs 3000 amplifier, though its impact is more indirect in loudspeaker systems compared to electronics. Let’s explore this:
Miller Effect Overview
Role in Damping
Impact on Perception
The Miller effect subtly affects damping at high frequencies, minimally impacting your 30 Hz focus but worth DSP tuning. (19 words)
If thats not how it works then maybe someone can elaborate on how it truly works...
Otherwise AI isnt shy;
At 11:05 PM EDT, Saturday, July 05, 2025, the Miller effect plays a nuanced role in damping for your four Acoustic Elegance 18H+ and NMB 600 woofers (32Ω series load, adjusted 88.5 dB/1W/1m at 30 Hz) driven by a Crown CTs 3000 amplifier, though its impact is more indirect in loudspeaker systems compared to electronics. Let’s explore this:
Miller Effect Overview
- Definition: The Miller effect refers to the increase in effective input capacitance of an inverting amplifier due to the feedback capacitance between input and output, amplifying the capacitance by a factor of (1 + gain). In audio amplifiers, this typically applies to the output stage transistors or op-amps.
- Context: In your setup, it affects the amplifier’s output impedance and frequency response, influencing how it interacts with the speaker’s back-EMF.
Role in Damping
- Amplifier Output Impedance:
- The Miller effect increases the effective capacitance at the amp’s output, slightly raising ( Z_{\text{out}} ) (e.g., from 0.1Ω to a frequency-dependent value). This reduces the damping factor (DF = ( \frac{R_{\text{load}}}{Z_{\text{out}}} )), which is 320 (series), 20 (parallel), and 80 (series-parallel) in your case.
- Impact: A higher ( Z_{\text{out}} ) at high frequencies weakens the amp’s ability to damp back-EMF, potentially causing transient overshoot, especially at 115 dB/30Hz peaks.
- Frequency Dependence:
- The Miller effect is most significant at higher frequencies where capacitance reactance (( X_C = \frac{1}{2\pi f C} )) decreases. At 30 Hz, the effect is minimal (e.g., ( X_C ) is large), but it grows above 100 Hz, affecting damping consistency across your woofer’s range.
- Perception: Subtle roll-off or phase shift at higher frequencies may soften perceived treble clarity, though your 30 Hz focus sees little impact.
- Interaction with R_loop:
- Your ( R_{\text{loop}} ) values (56Ω series, 3.5Ω parallel, 14Ω series-parallel) dominate ( I_{\text{damp}} ) (0.241A, 3.86A, 1.93A), but the Miller effect modifies the amp’s response to back-EMF. In series (high ( R_{\text{loop}} )), the effect is less noticeable due to low current, while parallel (low ( R_{\text{loop}} )) may amplify transient errors.
- Mitigation:
- The CTs 3000’s high DF (>3000 at 10-100 Hz) and robust design likely minimize Miller effect influence at 30 Hz. Using DSP to flatten response can further compensate.
Impact on Perception
- At 115 dB/30Hz, the Miller effect’s damping impact is negligible, but at higher frequencies, it may slightly blur transients (5-10% perceived softening) in parallel due to lower DF. Series’ high DF counters this better.
The Miller effect subtly affects damping at high frequencies, minimally impacting your 30 Hz focus but worth DSP tuning. (19 words)
The cold, pointy pencil is only used to write words with an even number of letters.
You suggest that a series connected driver produces a backEMF which then encounters the impedance of the other driver as it seeks to pass current through the short circuit of the amplifier output. You suggest that this affects damping, but that it balances out due to the relative levels of this load shared between the drivers.
During this time, what is the other driver doing?
You suggest that a series connected driver produces a backEMF which then encounters the impedance of the other driver as it seeks to pass current through the short circuit of the amplifier output. You suggest that this affects damping, but that it balances out due to the relative levels of this load shared between the drivers.
During this time, what is the other driver doing?
I am saying that for back emf to reach to amplifier it has to travel through resistance of the circuit. X amount of voltage at 2ohms or 32ohms results in different power. Damping Factor adjust according to the deficit of power due to circuit resistance.
Have you changed the question now? Are you talking about the damping of one driver of a series pair in the presence of the second driver, like here...
If we're still talking about the first, what is the other driver of a series connected pair doing while the first is producing the backEMF?
or are you now talking about the relatively insignificant overall damping factor?
If we're still talking about the first, what is the other driver of a series connected pair doing while the first is producing the backEMF?
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I've always been talking about how back emf is treated by the amplifier.... that fake quote from AI lying to me.... who knows whats going on... I never expected AI to pass fictional quotes as real AES quotes (lol) so I was putting it out there like hey guys look at this.... wiring typology doesn't change qes... If one driver is creating back emf so is the other one, on the same circuit??? The resistance in the loop affects each the same? Practically speaking?
Right. So they are both shuffling along the same current. Effectively they're line dancing together, which means one doesn't trip over the other one. It's like the other driver isn't even there. This is why Qes doesn't change when you put two in series.
I think the OPs requirement is high SPL, hence the need for the large horn wide band…..I haven’t read this thread through though as no insult meant for the OP……there’s no clarity to method…..it’s random assertions like throwing $h!t on the all and keeping what sticks and doesn’t smell too bad.
Given what I’ve learned through practical knowledge and understanding my own hearing and room acoustics along with fundamental tones…..well…….if I were to approach this, a two way line array is the way I’d handle this……a long line of 130mm woofers paired to a line of AMTs or Ribbons crossed appropriately for the tweeter used………AMTs can be crossed very low when used in multiples………a line of 8 could easily be crossed at 1500hz and not create any horizontal or vertical lobes from the midwoofers to the tweeters or the midwoofers to eachother.
The lobing issue is on the vertical axis tweeter to tweeter. AMTs and ribbons don’t have an acoustic center……it’s the flange to flange distance that creates issues. Attempt to mitigate this have been fairly easy and successful with both mechanical and electrical solutions…..power tapering and shaped foam blocks at the vertical ends of each AMT.
No, it drops from 98dB ~275Hz down to 78 dB at ~575Hz, 20dB in under one octave.
It makes no sense to slot load woofers to create a 20dB null, then "sculpt it by EQ" to what it would be if the response had not been screwed up.
Keeping it in context, there are very good reasons you don't see slot loaded woofers used for transition to the high frequency driver, and why using a high frequency horn driver from under 300Hz to 20,000Hz is not a good choice for high SPL, low distortion reproduction.
Everything is relative to your perception, if you compare the response of a 2x18" slot loaded subwoofer that drops at a rate greater than 24dB per octave from 120Hz to 30Hz, you could say anything "did good".
Even considering the subtle Miller effect on damping when you have decided on using a design that ruins frequency response and increases midrange ringing is like worrying about how your hair looks on an open boat on the water during a hurricane 😉 .
Art
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There are examples that show a high frequency horn driver with wide bandwith can be a good choice for high spl and low distortion. You shurely know this and you probably mean it in the context of Camplo his creation, but just for the record.... I disagree with this statement.
I would guess he means taking it too low in frequency, in which case I would agree.
I am trying to see what you see.... Here are some gated measurements of a single 15" and the 15"PPRSL.... Whats all the commotion about?
Both are shown with a 220hz LR24db low pass. Sculpting is just another word for voicing. We all voice drivers. We all sculpt the low end. I am trying to see your perspective in reality. Changing the low pass to 300hz yields similar results., The end result is practically identical with slot or no slot......
I haven't made it outside but looking at the indoor close proximity measurements is telling. After voicing, the first slot had no issues ringing. These improved slots will follow suit. The ringing of the room completely over shadows the slots decay by a long shot. Ringing, also being a function of FR, can be remedied by smoothing out the FR with EQ. Here is an up close measurement of the slot with gate at 500ms....There is the low pass at 220hz (LR24db). the notch in the middle is from room eq... effectively its rolling off closer to 200hz but.....
Ringing is just not there buddy.....
Pretty good for a slot. The res at 100hz is the room.
Crossed at 302hz same filter type. Still no ringing....
There better not be any ringing where it matters otherwise i did all this work for nothing lol. These are up close measurements of the new 15prsl vs outdoor measurements of the old 18ppsl,no filtering. The area of resonance at >300hz is a non issue.
Ringing isn't an issue... FR isn't an issue.....
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