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50.25.77.228
asking QWEN - my input could be better for it to digest
Its assumptions may not be the best
:
Hi QWEN -
I'd like for you to design a folded midbass horn including back chamber volume around Thiele-Small parameters.listed below. (Kappa 12A if its asked to use Kappa 12A then it pulls another driver's parameters with qts=0.44) Its use of St=Sd "interesting" ;^)
At least its cheerful and upbeat - lol
I'd like to have cutoff in the 75Hz region. I'd like to limit total external bulk to 150 liters and have internal horn width 22.5 inches.
Fs = 45 Hz
Re=5.41 ohm
Le = 0.77mH
Sd = 519.5 cm2
Vas = 112.1 liters
Qes = 0.28
Qms = 7.76
A prediction of frequency response and SPL in 2pi from 50Hz to 2000Hz would be helpful
profile
Qwen2.5-Max
Designing a folded midbass horn involves balancing the acoustic properties of the horn with the physical constraints you've provided. Below, I'll walk through the design process step-by-step, including calculations for the horn geometry, back chamber volume, and predictions for the 2π frequency response and SPL from 50 Hz to 2000 Hz.
Step 1: Understanding the Requirements
Cutoff Frequency (Fc): 75 Hz
Total External Volume: ≤ 150 liters
Internal Horn Width: 22.5 inches (57.15 cm)
Thiele-Small Parameters:
Fs = 45 Hz
Re = 5.41 ohms
Le = 0.77 mH
Sd = 519.5 cm²
Vas = 112.1 liters
Qes = 0.28
Qms = 7.76
The goal is to design a horn that:
Provides efficient coupling at frequencies above the cutoff (75 Hz).
Maintains compact dimensions within the given external volume.
Minimizes distortion and maintains smooth frequency response.
Step 2: Horn Design Basics
A horn's geometry is determined by its throat area (St) , mouth area (Sm) , and length (L) . The expansion rate is typically exponential or hyperbolic to ensure smooth impedance matching.
Key Equations:
Cutoff Frequency (Fc): Fc=4⋅Lc
Where c is the speed of sound (343 m/s), and L is the horn length.
Mouth Area (Sm):
The mouth area must be large enough to radiate efficiently at the cutoff frequency. A rule of thumb is: Sm≥2πλ2
Where λ=Fcc.
Throat Area (St):
The throat area should match the driver's surface area (Sd) to avoid compression losses.
Back Chamber Volume:
The back chamber volume affects the system's resonance and compliance. It should be designed to complement the horn's acoustic load.
Step 3: Calculations
1. Mouth Area (Sm):
At 75 Hz:
λ=Fcc=75343≈4.57mSm≥2πλ2=2π(4.57)2≈3.34m2=33400cm2
2. Throat Area (St):
Given Sd=519.5cm2, we set St=Sd=519.5cm2.
3. Horn Length (L):
Using the cutoff frequency equation:
Fc=4⋅Lc⟹L=4⋅Fcc=4⋅75343≈1.14m=114cm
4. Expansion Rate:
The horn's cross-sectional area expands exponentially from throat to mouth:
S(x)=St⋅em⋅x
Where m is the flare constant:
m=Lln(Sm/St)
Substitute values:
m=114ln(33400/519.5)≈0.043cm−1
5. Back Chamber Volume:
The back chamber volume is chosen to tune the system. Since the total external volume is limited to 150 liters, and the horn itself occupies some space, the back chamber volume should be approximately:
Vb≈1.2⋅Vas=1.2⋅112.1≈134.5liters
This leaves about 15.5 liters for the horn structure.
Step 4: Frequency Response and SPL Prediction
To predict the frequency response and SPL in 2π space (half-space radiation), we use the following considerations:
Below Cutoff (Fc = 75 Hz):
Output rolls off at ~12 dB/octave due to the horn's inability to radiate efficiently.
Above Cutoff:
Output increases with a slope of ~6 dB/octave until it flattens out at higher frequencies.
The horn provides high efficiency due to impedance matching, resulting in high SPL.
Key Points for Frequency Response:
At 75 Hz: Transition point where the horn starts to radiate efficiently.
At 150 Hz: +6 dB/octave slope begins to flatten as the horn reaches its optimal operating range.
Above 200 Hz: Flat response due to full horn loading.
SPL Calculation:
The SPL can be estimated using the driver's sensitivity and the horn's efficiency gain. Assuming the driver has a free-air sensitivity of 90 dB/W/m, the horn adds approximately 10-12 dB of efficiency gain:
SPL=Driver Sensitivity+Horn Gain
For example:
At 75 Hz: 90+6=96dB SPL
At 150 Hz: 90+10=100dB SPL
At 500 Hz: 90+12=102dB SPL
Step 5: Predicted Frequency Response and SPL
Below is the predicted 2π frequency response and SPL from 50 Hz to 2000 Hz:
50
-12
78
75
0
96
100
+3
99
150
+6
102
200
+8
104
500
+10
106
1000
+12
108
2000
+12
108
Step 6: Summary
Horn Dimensions:
Length: 114 cm
Throat Area: 519.5 cm²
Mouth Area: 33400 cm²
Expansion Rate: Exponential with m=0.043cm−1
Back Chamber Volume: ~134.5 liters
Frequency Response:
Smooth roll-off below 75 Hz
Efficient output above 75 Hz with a flat response at higher frequencies
SPL:
96 dB at 75 Hz
108 dB at 1 kHz
This design meets your requirements for a compact, efficient midbass horn with a cutoff at 75 Hz and a total external volume of 150 liters.
Final Answer:
Horn Length: 114 cm, Throat Area: 519.5 cm², Mouth Area: 33400 cm², Back Chamber Volume: 134.5 liters, Predicted SPL: 96-108 dB (50 Hz-2000 Hz)
Karlson Evangelist
Follow Ups:
Hi Freddyi
Hope your well.
How high do you really need to go?
The sensitivity for a best alignment goes down fast as you increase the target bandwidth.
Tom
and Hoffman's Iron Law still applies, AFAIK.
yep - bulk for bulk a multi driver direct radiator may do better in some instances than a horn. With current inflation and Eminence prices basically doubled while my income dropped - I'd take the horn.
Did any forums replace the once interesting and varied Klipsch Tech-mod forum? Diyaudio seems opposed to a "horn" forum.
Karlson Evangelist
Almost all DIY places are Direct Radiator biased 95%!!!
Why, because good horns, while easier than ever to design with computer tools, CNC, and 3D Printing, it's still much EASIER to do direct radiators.
Especially since 99% of program material is compressed to +/-1 Decibel from Zero!
Who needs dynamics and headroom when there's no reason for it in POP music, which outsells the "great jazz stuff" by a huge margin.
Market realities still dominate.
hey Tom - hope you're doing well. I'm ok but fat - non cancerous kidney tumors, diabetes, rickety heart, non convergent vision and hernias which doc won't operate on as he thinks will kill me. (my opinion = am somewhat tougher than they think as their automated pulseometers can't read A-Fib stuff)my main complaint - have pretty much lost use of my arms - horrible tendonitis in both arms - probably from years of frozen shoulders - hope to get hydrodilation of the shoulders
RE: the horn - its more an exercise to see how well the chatbot can understand and spit out something of use.My stuff is at my house only a mile away but cannot get to. I have two horns where I currently live - a 12/15 scale Belle with Kappa12a and a little J-path horn designed by LORDSANSUI called "smallhorn2 with a cheapo Tymphany 10" driver - I think with a lowpass filter pulling more current that I can get its 1KHz area a bit louder for a better mach to the B52 horn - that horn at #3.95 blowout was the bargain of the century )
A previous C path horn by RCA-Fan was pretty good - just lacking a reflector at the first bend so was getting rough near 500Hz tops.
70Hz to 600Hz (xover to midrange horn) with acceptable "coloration" would be a very good horn. I'm not bothered with the mini Belle or Smallhorn3 with crossover to a B52 horn and B&C DE25 @~1200Hz.
Karlson Evangelist
Edits: 03/14/25
You are an incorrigible hobbyist to the end.
Great disease many of us have. I've slowed down a bit of my projects and selling off all the stuff that pales in comparison to Tom Danley's designs and production units.
It's hard to improve on the best, while the other turkeys and chickens just buy more watts and live with limits of voice coil thermal compression in direct radiators, the "capacitors that wiggle just a Little" as Electrostatics, or the less limited but still power hungry planar magnetics.
There's a reason Oskar Heil's invention is limited to tweeters, of which the original/best are a bipolar conical horn anyhow.
I applaud Tom's methods of "chasing the right ideas" and the PROOR, as they say, is in the PROVEN Production Pudding!
So, won't you joint me at the "end of the line" with Tom Danley's products and just enjoy the music for whatever time you have left.
re: joiningI'm down on "money" these days. Have 37 gas wells - each paid $40 - for a month - $1.33 per day. My taxes on gas are maybe $2500 per year - so last years income ~$17,500 - doesn't go very far.
Do have Ton's prototype Unity horns - maybe one as I've not been to my house only a mile away more than a few times in the last 5 years. I've not driven sine 1996 - no car - vertigo for over 50 years - double vision for the lst few years - my kid is paralyzed on his right side from a car accident and suffers from severe vertigo. He sure tries to move and will push a lawn mower on a hot day for over an hour.
Anyhow -
Here's what the China based chatbot "Qwen" says regarding jazz - it sounds like that genre has suffered too
WHICH JAZZ ALBUMS AT THE DYNAMIC RANGE DATABASE "HAVE THE HIGHEST DYNAMIC RANGE"?
profile
Qwen2.5-Max
The Dynamic Range Database (DR Database) is a resource that measures the dynamic range of audio recordings, including jazz albums. Dynamic range refers to the difference between the quietest and loudest parts of a recording, and it is often used as an indicator of audio quality. Albums with higher dynamic range values are generally considered to have better sound quality because they preserve more nuances in the music.
To determine which jazz albums have the highest dynamic range according to the DR Database, we need to consider the following:
How the DR Database WorksDR Value : The database assigns a numerical value (e.g., DR8, DR12) to each album or track. Higher numbers indicate greater dynamic range.
Jazz Genre : Jazz is known for its dynamic expression, so many high-DR albums tend to come from this genre.
Album Selection : The database includes user-submitted data, so not all jazz albums are listed. However, some trends can be identified based on available entries.
High Dynamic Range Jazz Albums
Below is a list of jazz albums known for their high dynamic range, based on data from the DR Database and general audiophile knowledge:
1. Miles Davis - Kind of Blue (1959)DR Value : DR14-DR16
Why It Stands Out : This iconic album is celebrated for its minimalist production and spacious sound, allowing instruments to breathe. The original recordings, especially on vinyl or high-quality CD remasters, exhibit excellent dynamic range.
2. John Coltrane - A Love Supreme (1965)
DR Value : DR13-DR15
Why It Stands Out : Coltrane's masterpiece is recorded with clarity and depth, capturing the emotional intensity of the performance without compression.
3. Dave Brubeck - Time Out (1959)
DR Value : DR12-DR14
Why It Stands Out : Known for its innovative rhythms and acoustic instrumentation, this album benefits from a natural, uncompressed sound.
4. Bill Evans Trio - Waltz for Debby (1961)
DR Value : DR13-DR15
Why It Stands Out : Recorded live at the Village Vanguard, this album captures the intimate interplay between the musicians with minimal processing.
5. Thelonious Monk - Monk's Dream (1963)
DR Value : DR12-DR14
Why It Stands Out : Monk's unique piano style and the album's balanced recording make it a standout in terms of dynamics.
6. Pat Metheny Group - Still Life (Talking) (1987)
DR Value : DR13-DR15
Why It Stands Out : While not traditional jazz, this album blends jazz with world music and features expansive arrangements with plenty of dynamic variation.
7. Chick Corea - Return to Forever (1972)
DR Value : DR12-DR14
Why It Stands Out : As a fusion classic, this album combines jazz improvisation with rock energy, maintaining a wide dynamic range.
8. Ella Fitzgerald & Louis Armstrong - Ella and Louis (1956)
DR Value : DR13-DR15
Why It Stands Out : The vocal interplay and acoustic backing create a natural, uncompressed listening experience.
9. Charles Mingus - The Black Saint and the Sinner Lady (1963)
DR Value : DR12-DR14
Why It Stands Out : Mingus' orchestral approach to jazz allows for dramatic shifts in volume and texture, resulting in a high dynamic range.
10. Wynton Marsalis - Black Codes (From the Underground) (1985)
DR Value : DR13-DR15
Why It Stands Out : Marsalis' modern take on traditional jazz emphasizes clarity and dynamic expression.
Key Observations
Vintage Recordings : Many high-DR jazz albums come from the pre-digital era (1950s-1970s), when analog recording techniques prioritized natural sound over loudness.
Remasters : Modern remasters of classic albums may vary in dynamic range. Some remasters preserve the original dynamics, while others suffer from excessive compression.
User Submissions : The DR Database relies on user contributions, so the availability of specific albums may vary. For the most accurate information, you can search directly on the DR Database website .
Karlson Evangelist
Edits: 03/17/25
I have at least half of your list in my collection. All good. Thanks for posting.
It doesn't appear that chatbot knows how to use HornResp. 70 to 600Hz isn't at all difficult.
I have done one that is 140 to 1 Khz., midbass Tractrix with a 12" Eminence Delta Pro 12a.
Edits: 03/17/25
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