Another thing to consider is the pioneers 'critically' damped not just the vent, but the driver also, i.e. they voiced the system using grill cloth and at least one reason why we see such a wide range of materials/densities back then.
Right, hi-pass/TT 'rumble' filters were sometimes added to the amp, though normally its frequency response was rolled off to compensate and need to keep in mind that as late as the early '70s the recorded music norm was flat to 80 Hz, -24 dB/40 Hz and prosound till at least into the mid '90s.
Note too that because of all this, speakers were typically tuned between ~50-65 Hz, so even big reflex vents weren't noisy like today's vents, but did leak out an audible low SPL, 'ghost' mid-bass, lower mids at higher average SPLs if no grill cloth.
Way back then only a few $pecially recorded RTR tapes output an honest < 20 Hz, one of which was of a steam locomotive @ ~120 mph that my first full time boss had used in a Halloween prank, causing one heart attack among some others' various physical 'responses'.
On a somewhat unrelated note, I received my UMIK-1 and did some measurements, and then corrections and my current setup (two bookshelf active speakers with a 5" woofer and a 1" soft dome tweeter).
As expected, it doesn't do much below 45Hz. I can't wait to get my SB20FRPC30s and hear how different they sound from my current rig. Surely they'll be a big improvement in the bass region.
As expected, it doesn't do much below 45Hz. I can't wait to get my SB20FRPC30s and hear how different they sound from my current rig. Surely they'll be a big improvement in the bass region.
I haven't decided just yet. I want to learn HornResp a little better and make a more educated choice. I've been watching/reading all I could find and I'm just now being introduced to group delay, impedance and all that... Plus, I haven't received the drivers just yet. But I'll make a decision as soon as I do!
In the meantime, I started looking at amplifiers and amplification solutions, but I'm still somewhat overwhelmed. I have made a post about this just now actually.
In the meantime, I started looking at amplifiers and amplification solutions, but I'm still somewhat overwhelmed. I have made a post about this just now actually.
Understood, there's a small library's worth of tech info to learn, though lucky not to have to learn it the hard way as many here did over the decades and/or via higher education; as they say, 'Rome wasn't built in a day', just nowadays with all the technological advances growing ~ exponentially or maybe moving towards hyperbolic, we can do it so much quicker, better than they could even imagine unless the powerful drugs they regularly used gave them such fantasies.
I found this thread of ASR. Someone who's built a 12L sealed enclosure for the SBFRPC30. How can a sealed box so tiny can achieve such an amount of extension??? Here are his measurements:
Uncorrected response :
Corrected with DSP (25Hz??) :
Distorsion graph :
Uncorrected response :
Corrected with DSP (25Hz??) :
Distorsion graph :
… for the SB20FRPC30
Calculates closer to a 14.8 litre enclosure.
The answer to you question. Wall. Room.
dave
....and speaker system design is all about trading efficiency for BW.
This isn't considered a TL, right?
I have received the drivers, but I haven't made enough progress to even consider designing my first TL. That would postpone actually hearing anything from the drivers for a good few months. Unnaceptable!
I quite like the way this one looks, and would like to give it a go as a first build. I'll make it out of 20mm XPS foam, but I have a few questions.
1) What are the advantages of going for a TL over this sort of design?
2) Could I get away with not using double thickness for the walls but good bracing throughout?
Hey @Scottmoose, I was browsing the thread where you post your designs and saw that you designed a MLTL for the SB driver.
I still have trouble understanding how this design differs from a regular bass reflex. What makes it a MLTL?
Does that mean the design I referenced just one post above is also an MLTL?
I still have trouble understanding how this design differs from a regular bass reflex. What makes it a MLTL?
Does that mean the design I referenced just one post above is also an MLTL?
As Dave said. Expanding a little, a bass reflex or typical vented box uses Helmholtz (cavity) resonance as its sole intended internal loading arrangement, and either assumes a uniform internal air-particle density with no standing waves present, or takes some kind of measures in the design to ensure that is the only functional loading. An MLTL deliberately generates and uses standing waves (eigenmodes) via its internal proportions / geometry as a functional part of its alignment.
The cabinet referenced on this thread is intended as a traditional vented box alignment; there isn't any functional QW loading in its alignment.
The cabinet referenced on this thread is intended as a traditional vented box alignment; there isn't any functional QW loading in its alignment.
Things are finally starting to click... thanks for all your answers. Been feverishly taking notes, reading all I could find, sifting through posts and toying with HornResp, Akabak and SpicyTL to get the hang of running simulations.
I have one questions regarding stuffing. I have received the drivers and I now have everything I need to build a few different designs out of XPS to try different types of alignments and how they sound. The only thing I'm missing is proper stuffing materials.
I'd like to order enough stuffing to be able to try different things, but I'm lost as to what I should get. Polyfill? Rockwool sheets? How thick?
I get the idea that a TL shouldn't be filled all the way, but only portions of the length. But are these portions lined, or filled with balls of wool? Does the damping material affect the overall volume of the cabinet, and should I design around that fact before building my prototypes?
I can order dedicated hifi stuffing or try and get my hands on something else if it's easier & cheaper.
I have one questions regarding stuffing. I have received the drivers and I now have everything I need to build a few different designs out of XPS to try different types of alignments and how they sound. The only thing I'm missing is proper stuffing materials.
I'd like to order enough stuffing to be able to try different things, but I'm lost as to what I should get. Polyfill? Rockwool sheets? How thick?
I get the idea that a TL shouldn't be filled all the way, but only portions of the length. But are these portions lined, or filled with balls of wool? Does the damping material affect the overall volume of the cabinet, and should I design around that fact before building my prototypes?
I can order dedicated hifi stuffing or try and get my hands on something else if it's easier & cheaper.
Damping approach depends on the design.
An ML-TL for instance can be damped as simply as a reflex (lined) but requires other measures to create teh wanted low pass at the terminal (driver offset, line shape…) and will sometimes have a bit more ripple (or a lot as in an unloaded BIB), or partially ot fully stuffedto push things more aperiodic. The last is usually our default.
We use acoutastuff (hi-end polyfluff), sometimes Ultratouch insulation, and heavily use UltraTouch felt for reflex-style damping and for extra near the back of the driver to help kill reflections back thru the driver.
Note that it takes a LLOOONNNGGG time to properly tease polyfill in general, but acoutstuff is really tedious. It should be very even. But one can use that well-teased polyfill at different densities at different places. This technique is used in the point of the Frugel-Horns, and there is a bit of discussion about it in the Pro9 TL articles (the idea being that one can increase densities at the peak points of a particular harmonic to maximize the reduction of tha harmonic while damoing less of the wanted harmonic).
http://p10hifi.net/TLS/downloads/Pro9TL-1.pdf
http://p10hifi.net/TLS/downloads/Pro9TL-Mk2.pdf
dave
An ML-TL for instance can be damped as simply as a reflex (lined) but requires other measures to create teh wanted low pass at the terminal (driver offset, line shape…) and will sometimes have a bit more ripple (or a lot as in an unloaded BIB), or partially ot fully stuffedto push things more aperiodic. The last is usually our default.
We use acoutastuff (hi-end polyfluff), sometimes Ultratouch insulation, and heavily use UltraTouch felt for reflex-style damping and for extra near the back of the driver to help kill reflections back thru the driver.
Note that it takes a LLOOONNNGGG time to properly tease polyfill in general, but acoutstuff is really tedious. It should be very even. But one can use that well-teased polyfill at different densities at different places. This technique is used in the point of the Frugel-Horns, and there is a bit of discussion about it in the Pro9 TL articles (the idea being that one can increase densities at the peak points of a particular harmonic to maximize the reduction of tha harmonic while damoing less of the wanted harmonic).
http://p10hifi.net/TLS/downloads/Pro9TL-1.pdf
http://p10hifi.net/TLS/downloads/Pro9TL-Mk2.pdf
dave
You will need to have
1. Damping material around the driver to reduce reflections from the surfaces
2. Add a lot of damping material between the driver and the closed end (it will reduce harmonics with little effect on the fundamental resonance)
3. Then comes the tricky part, reducing the harmonics while keeping the fundamental resonance working
In all cases the damping works best at velocity maxima and has the least effect on pressure maxima/velocity minima.
The fundamental is easy pressure max at closed end and velocity max at pipe opening. (so use as little damping as possible far from the closed end)
The unwanted odd harmonics has velocity max at their geometric distances.So 3rd harmonic an 1/3 and 2/3 from closed end . 5th 1/5, 2/5 3/5 4/5 from closed end. And so on for higher harmonics. This is for a straight pipe of constant cross section.
Adding bends, foldings positive or negative taper shift the harmonics around compared to the fundamental
It still pans out to by having a lot of damping the the first 1/3 to 1/2 of the pipe the harmonics is reduced a lot.
Trying for taming specific resonances at 2/3 and 3/5 would be really tricky as they probably are located at other places then the plain geometric distances from the closed end.
1. Damping material around the driver to reduce reflections from the surfaces
2. Add a lot of damping material between the driver and the closed end (it will reduce harmonics with little effect on the fundamental resonance)
3. Then comes the tricky part, reducing the harmonics while keeping the fundamental resonance working
In all cases the damping works best at velocity maxima and has the least effect on pressure maxima/velocity minima.
The fundamental is easy pressure max at closed end and velocity max at pipe opening. (so use as little damping as possible far from the closed end)
The unwanted odd harmonics has velocity max at their geometric distances.So 3rd harmonic an 1/3 and 2/3 from closed end . 5th 1/5, 2/5 3/5 4/5 from closed end. And so on for higher harmonics. This is for a straight pipe of constant cross section.
Adding bends, foldings positive or negative taper shift the harmonics around compared to the fundamental
It still pans out to by having a lot of damping the the first 1/3 to 1/2 of the pipe the harmonics is reduced a lot.
Trying for taming specific resonances at 2/3 and 3/5 would be really tricky as they probably are located at other places then the plain geometric distances from the closed end.
@pardon
I really like your taste in Overall cabinet aesthetics.
And Your appreciation for older Altec designs and modern
builds using wide baffles.
Best advice is to not overthink and just shoot for classic alignments.
This driver does well in 60 to 100 liters
And normal everyday QB3 alignment and SB4 are both around 100 liters
and 35 Hz reflex.
Make the baffle wide like you want, and then use depth needed
to get the volume correct.
When it comes to full range drivers there is a certain magic
about them. For some reason 8" drivers are fun. Because it allows
large boxes that we like so much.
It is possible to spend hours and months of your life to
figure out ways to try and weasel more bass out of a single
speaker.
Just learned speakers just are what they are.
Its a decent 8" with 4mm xmax and pretty good
Fs. Go for standard alignment and call it a day.
Build the box you want. Bass will be good
on a wide baffle and somewhat in the corners
as shown will give deeper extension.
Being a electronic music fan and having produced
and monitored endless tracks. If the 8" dont give you
life changing deep bass. A simple 12" sub will.
since you have no size restraints.
I really like your taste in Overall cabinet aesthetics.
And Your appreciation for older Altec designs and modern
builds using wide baffles.
Best advice is to not overthink and just shoot for classic alignments.
This driver does well in 60 to 100 liters
And normal everyday QB3 alignment and SB4 are both around 100 liters
and 35 Hz reflex.
Make the baffle wide like you want, and then use depth needed
to get the volume correct.
When it comes to full range drivers there is a certain magic
about them. For some reason 8" drivers are fun. Because it allows
large boxes that we like so much.
It is possible to spend hours and months of your life to
figure out ways to try and weasel more bass out of a single
speaker.
Just learned speakers just are what they are.
Its a decent 8" with 4mm xmax and pretty good
Fs. Go for standard alignment and call it a day.
Build the box you want. Bass will be good
on a wide baffle and somewhat in the corners
as shown will give deeper extension.
Being a electronic music fan and having produced
and monitored endless tracks. If the 8" dont give you
life changing deep bass. A simple 12" sub will.
since you have no size restraints.
Last edited:
With dimentions adjusted to working volume of the SB driver,
I finally got back from my vacation and fired up HornResp thinking I had read enough to be able to design a MLTL for the drivers, but I still can't wrap my head around how I should be going with this. Even after parsing Planet10's and Scott's designs and somewhat reverse engineering and taking notes, I cannot figure out a way to make a wide baffle MLTL.
I might just go with a regular vented box. I really wanted to try a more exotic alignment, but I can't be asking for help left and right...