Case for Discussion - Would a Single driver Manifold/MTB be better than Tapped Horn?

Jump to Latest
#201
How does a ROAR function @ the second resonace (which seems to be close to twice the fundametal )? The path lengths seem to be related as well

Driver entry points @ blue X’s

Both ends of the driver are in a high pressure zone at Fb 2?

The waterfall measurements of mine suggests the second resonace isn’t ringing much at all and group delay is ~ 10msec at 70 hz
 

Attachments

  • image.jpg
    image.jpg
    689.7 KB · Views: 10
Last edited:
#203
Rik_bS said:
I wouldn't go as far as saying that... There are many successful deployments of TH, and they'd all have ways to handle that noise out of passband. Ie, low mid "kick bins" or having tops that go low enough to cross over and avoid it.
Click to expand...

Yup. Basically they're bandpass designs with "poor" out of band response, but that could be dealt with via DSP and filtering.

This TH (one I built) looks it can be used up to 200 Hz, after DSP is used. In reality, using it over 120 Hz or so is pushing it a bit. I typically use it from 40 Hz to approximately 100 Hz.

1748654805606.png
 
  • Like
Reactions: maxolini and Rik_bS
#204
Booger weldz said:
Both ends of the driver are in a high pressure zone at Fb 2?

The waterfall measurements of mine suggests the second resonace isn’t ringing much at all and group delay is ~ 10msec at 70 hz
Click to expand...
yes. The front resonator will excert positive acoustic feedback through the driver over most of the midbass. This effect can be seen in the diaphragm pressure when comparing pressure front and back of the driver with the spl graph.
Both ends of the driver are in a high pressure zone at Fb 2 but the pressure at the driver side protruding into the front resonator is lagging behind one whole wavelength at F2.
 
  • Like
Reactions: Booger weldz
#205
Brian Steele said:
Yup. Basically they're bandpass designs with "poor" out of band response, but that could be dealt with via DSP and filtering.

This TH (one I built) looks it can be used up to 200 Hz, after DSP is used. In reality, using it over 120 Hz or so is pushing it a bit. I typically use it from 40 Hz to approximately 100 Hz.

View attachment 1467120
Click to expand...
I forgot to mention that one of the main advantages of a TH IMO, apart from the perhaps better cooling available for the driver, is that the effective radiating area is typically several times Sd, the radiating area of the driver. This results in pretty low "vent compression" effects, which I think contributes to that "effortless bass" sound that I really like. I measured as low as 0.3dB at the 10% in-band THD limit for my POC3 TH. The 50 Hz ODTL I built for the same driver with a much smaller mouth showed 2dB of compression at Fb before it reached 10% THD in-band. A 40 Hz ODTL with a larger mouth using the same driver showed about 1dB of compression at Fb. My takeaway from these projects is to make the radiating area as large as possible around Fb, which basically eliminates most simple vented designs 🙂.
 
  • Like
Reactions: maxolini, lonelybabe69, Booger weldz and 2 others
#206
Circlomanen said:
yes. The front resonator will excert positive acoustic feedback through the driver over most of the midbass. This effect can be seen in the diaphragm pressure when comparing pressure front and back of the driver with the spl graph.
Both ends of the driver are in a high pressure zone at Fb 2 but the pressure at the driver side protruding into the front resonator is lagging behind one whole wavelength at F2.
Click to expand...

If it was lagging behind by a full wavelength (360 degrees) then the output would be a deep notch/null (which it is further up in the frequency response when a full wavelength fits at 4 x that of the upstream pipe).
 
#209
Booger weldz said:
I don’t know how anyone can listen to a ‘tapped horn’ if the top of the bandwidth (and crossover region) is absolute chaos where vocals will howl/ring/linger, As well as the harmonics and details of bass Instruments ?

Art, recommends other designs if using the subwoofer into those frequencies at the start of the thread.

Don’t Danley products come with a pre-program, DSP and crossover?

Just use two drivers in two big vented reflex designs and avoid all of this ? (Add a short horn to the other side if you want ? It won’t have the chaos @ 3 x Fb that a tapped pipe/horn creates)
Click to expand...
Using a SUBwoofer to 200hz is the problem when 99% of the time they are used <100hz.

Now in the car audio world, SQ guys will run subs to 200hz when mounted in the front of the car in small sealed enclosures.

I had an upfront BP4 in my 1996 Ford Ranger SuperCab and ran it <120hz.

AMD60QBP44.jpg
AMD60QBP45.jpg
AMD60QBP47.jpg
AMD60QBP46.jpg
 
#211
Rik_bS said:
I wouldn't go as far as saying that... There are many successful deployments of TH, and they'd all have ways to handle that noise out of passband. Ie, low mid "kick bins" or having tops that go low enough to cross over and avoid it.
But as already mentioned in this thread, the design at hand enables a higher low pass - taking on the "kick" range, a big appeal if you want to run a two way crossover to smaller tops and negate the need for a low mid to bridge the gap.
Click to expand...

Then it's not a SUBwoofer anymore, it's kick or a bass bin like I said before.

That's why they make woofer and SUBwoofer drivers.

You audiophiles and PA guys are not trying go <41hz (standard 4 string bass). That's a concept I will never understand when a standard 88 key piano goes to 27.5hz.

But what do I know, I'm just a regular basshead.
 
#213
Brian Steele said:
Yup. Basically they're bandpass designs with "poor" out of band response, but that could be dealt with via DSP and filtering.

This TH (one I built) looks it can be used up to 200 Hz, after DSP is used. In reality, using it over 120 Hz or so is pushing it a bit. I typically use it from 40 Hz to approximately 100 Hz.

View attachment 1467120
Click to expand...

EXACTLY my point.

All TH's (ROAR, TQWP or TQWT, T-TQWT or T-TQWP, Paraflex) are series tuned 6th order BANDPASS enclosures.

A straight flare TH (TQWP or TQWT) can be modeled with the TH or BP6S function in HR. I think Booger uses the PH function too.
 
#214
Brian Steele said:
I forgot to mention that one of the main advantages of a TH IMO, apart from the perhaps better cooling available for the driver, is that the effective radiating area is typically several times Sd, the radiating area of the driver. This results in pretty low "vent compression" effects, which I think contributes to that "effortless bass" sound that I really like. I measured as low as 0.3dB at the 10% in-band THD limit for my POC3 TH. The 50 Hz ODTL I built for the same driver with a much smaller mouth showed 2dB of compression at Fb before it reached 10% THD in-band. A 40 Hz ODTL with a larger mouth using the same driver showed about 1dB of compression at Fb. My takeaway from these projects is to make the radiating area as large as possible around Fb, which basically eliminates most simple vented designs 🙂.
Click to expand...

And that's why I'll never build a direct radiator enclosure again.

📦🔊📦📣🎶
🎶📣📦🔊📦📣🎶
🎶📣🔊📣🎶
FOR LIFE!
 
#215
BP1Fanatic said:
Using a SUBwoofer to 200hz is the problem when 99% of the time they are used <100hz.

Now in the car audio world, SQ guys will run subs to 200hz when mounted in the front of the car in small sealed enclosures.

I had an upfront BP4 in my 1996 Ford Ranger SuperCab and ran it <120hz.
Click to expand...

The top of the bandwidth in a 30 Hz tapped horn is going to be 90 Hz, not 200.

The crossover region is a disaster

How many times is this repeated every week 😝
 
#216
Circlomanen said:
Positive acoustic feedback in a series-tuned bandpass enclosure inherently exhibits a nonlinear, exponential characteristic that fundamentally distinguishes it from mere passive resonance phenomena such as ringing or increased group delay. While it is true that the presence of positive feedback inevitably produces observable effects like ringing and elevated group delay in the upper portion of the passband—where the feedback mechanism is active
Click to expand...
So you are saying "positive acoustic feedback" exhibits a "nonlinear, exponential characteristic" that produces observable effects like ringing and elevated group delay in the upper portion of the passband.
Circlomanen said:
Specifically, the feedback mechanism effectively increases the driver’s virtual Bl product (force factor) within the targeted frequency range, producing an exponential response that counteracts nonlinear phenomena such as thermal and mechanical compression occurring at elevated sound pressure levels. The net result is a significantly enhanced resolution, definition, and transient fidelity in the reproduced waveform, particularly evident in the upper passband region.
Click to expand...
So now you say non-linear positive acoustic feedback effects like ringing and elevated group delay counteract other nonlinear phenomena, and their combined waveform distortions particularly evident in the upper passband region are "transient fidelity".
Circlomanen said:
To contextualize, the analogy to automotive turbocharging is apt: the turbo introduces a measurable lag and additional system complexity (analogous to group delay and ringing)
Click to expand...
A "measurable lag" and ringing does not enhance resolution, definition, or transient fidelity.
Circlomanen said:
In a BP6S enclosure, the positive acoustic feedback advantage arises from the acoustic pressure dynamics within the front chamber, which operates with approximately a full wavelength delay relative to the driver’s mechanical excitation of the first chamber and its associated port.
...This feedback loop introduces an additive component to the driver’s mechanical motion, resulting in a virtually increased Bl product within this frequency range. ...the delay-induced phase alignment allows the internally reflected acoustic energy to actively augment the driver’s output...The result is enhanced mid-bass efficiency, improved transient response, and greater dynamic control..
Click to expand...
Most sound engineers I've worked with would not equate mid-bass with approximately a full wavelength delay relative to the driver to "improved transient response", regardless of it being louder.

Art
 
#218
@Booger weldz what are those boxes you attached in post #184? They look so freaking sick!

Do any of you think this simple manifold design could benefit from either a cone corrector or letterboxing of the baffle? I can’t find much information about offset driver horns, and I’m wondering how bad the effects of the cone not being evenly loaded can be.
 
You must log in or register to reply here.
Top Bottom