Ok, so - 20:1 TL for both the speakers together, probably ending at the top of the speaker somewhere, or at the back at the top... I'll sort that out later.
Did you stuff the TL, or just leave it as is? I'll do some testing of my own, but when I put it together, I'd like to know what my best result will probably be.
Thanks again,
Chris
Did you stuff the TL, or just leave it as is? I'll do some testing of my own, but when I put it together, I'd like to know what my best result will probably be.
Thanks again,
Chris
Ok, so I made a test box with one woofer (works out around 17L), and 2 full rangers. Must be said - when I'm listening to that, the whole idea makes sense. Goes easily an octave lower than the speakers they are replacing, which is a good start, also, they look smaller - all you see is a thin line, compared to the Missions, which are relatively wide.
Integration isn't perfect yet, but it will be soon - messing with crossover points, but I think I'll go for around 300Hz.
Thanks for the idea, Dave
Chris
Integration isn't perfect yet, but it will be soon - messing with crossover points, but I think I'll go for around 300Hz.
Thanks for the idea, Dave
Chris
I didn't at first, but I think it's to do with the fact that, when you sit to one side or another, the woofers would, effectively be out of phase with each other at certain frequencies. Methinks the 300hz wavelength is too long to notice minor deviations from sitting dead in front of the speaker.
The test speaker seemed Ok, but it used up the woofer's excursion pretty quick, but I suspect adding another 3 of them would bring this down a fair amount for the same SPL...
Chris
The test speaker seemed Ok, but it used up the woofer's excursion pretty quick, but I suspect adding another 3 of them would bring this down a fair amount for the same SPL...
Chris
At sufficiently high frequencies is can be an issue (more so when drivers aren't symmetrical wrt the listener's head, but that is much higher than where a FAST is XOed.
dave
It's been agreed that, after listening to the test cabinet, we should make one of the boxes, to get a good idea of what it will sound like - the test box was big and unbraced, so we figured that, instead of rebuilding that box, it would be better to make our own. Going to get the wood cut at the store (a lot quicker than with a handsaw), but this will probably happen next weekend, as things like open evening are happening at school, then there's a weekend trip so it will be next week before anything gets done...
Chris
Chris
Proposal for FAST Speaker
I've been reading this thread with some interest. I've drawn up a proposal for a FAST speaker using Fostex FE167E and CSS SDX7.
I calculated the midbass based on Q=3/8 cubic ft (Bessel Butterworth) But now I need some help with working out "aperiodically damped 10:1 taper TL".
I would like to reduce the width of the cabinet, but need to figure out the full range side first.
I currently have MLTL's with FE167E, which I do like. However, my music collection dictates what I need more of, Midbass and BASS.
Thank You.
I've been reading this thread with some interest. I've drawn up a proposal for a FAST speaker using Fostex FE167E and CSS SDX7.
I calculated the midbass based on Q=3/8 cubic ft (Bessel Butterworth) But now I need some help with working out "aperiodically damped 10:1 taper TL".
I would like to reduce the width of the cabinet, but need to figure out the full range side first.
I currently have MLTL's with FE167E, which I do like. However, my music collection dictates what I need more of, Midbass and BASS.
Thank You.
Attachments
Bessel = 1/2 cubic ft
Butterworth = 1/4 cubic ft
I like to use 14-17 litre
With its much lower Fs you'll need a longer line for the FE167.
I suggest you fold it which would give about twice the length you have.
With the FE167 you can XO lower, with the FE127eN Fonken XO at 100 Hz which lets me mount the SDX7(s) at the floor for more room support.
dave
Here is Chris661's spinoff thread http://www.diyaudio.com/forums/full...ion-famous-tysen-speaker.html?highlight=Tysen
dave
dave
Tysen was not formed out of whole cloth.
After successfully hatching the mFonken, we still wanted something smaller. This led to the uFonken with the FF85. When we started this we knew that they would often get used with a woofer, and concurrently ordered a Keiga 2.1 amp and built a 14 litre sealed SDX7 woofer to go with the uFonken and hold the Keiga amp.
After listening to this for awhile* we decided that a pair of woofers that would act as stands.
*(not quite as planned -- the satelitte amps in the Keiga were prettry poor sounding, so we fudged that -- turns out that there is a compression cicrcuit in the HF amp chain that when removed improve things immensly)
This is what we started with.
I borrowed DCX2496, set upo the old G3 Lombard PowerBook with measuring mic/Fuzzmeasure and played with all sorts of XO arrangements.
With the DCX the only one happy with the sound was the measuring mic, but i learned a lot about XOing the combo -- for instance, as pictured the woofer is upside down -- i got quite severe combing until i fliipped it do the woofer was close to the mid-tweeter.
Attached is one of the FR curves. The limits at the bottom may not be the speaker but the Lombard's analog input and the roll-off at the top is from too long a mic cable. Althou a bit saddle shaped it is +/- 2dB from <30 Hz out to beyond 15k. There is a small amount of lift set at 25 Hz.
In the end i choose a 1st order XO on the woofer & 2nd order Bessel on the midtweeter at about 350 Hz. The low order XO on the woofer helps fill in the baffle-step loss. In this case the natural rolloff of the SDX7 above 1k doesn't hurt either.
A close approximation of this can be implemented as a PLLXO (Passive Line Level XO Passive High-Level Crossover).
dave
great. come on guy
I did a couple of versions:
A - Longer TL line with the SDX7 closer to the bottom, but further from the FE167E. No extra space.
B - Shorter TL line with the SDX7 farther from the bottom, but closer to the FE167E. Lots of extra space.
Each proposed has a 15L capacity for the SDX7, and the line was divided in three place it closer to the woofer.
Which would be better? Longer line, lower XO or Shorter Line, probably higher XO, but possibly less combing effects? Hmmm.
Thanks Dave and Martin King(for you worksheets)
Leo
Is that considered a small ML TQWT? Is the "Closed End and Ported Transmission Line" model applicable here?
I guess I don't really know what a aperiodically damped 10:1 taper TL is.
aperiodically - definition of aperiodically by the Free Online Dictionary, Thesaurus and Encyclopedia.
aperiodic [ˌeɪpɪərɪˈɒdɪk]
adj
1. not periodic; not occurring at regular intervals
2. (Physics / General Physics) Physics
a. (of a system or instrument) being damped sufficiently to reach equilibrium without oscillation
b. (of an oscillation or vibration) not having a regular period
c. (of an electrical circuit) not having a measurable resonant frequency
Does the 10:1 ratio mean the amount of damping that occurs in the TL from the ported end to the closed end. Further above you discussed denser damping at the terminus.
Thanks.
Leo
Leo,
It is a tapered TL. Aperiodic means it is heavily damped. For midrange use the stuffing gets denser as you approach the terminus, with almost none right behind the driver.
10:1 is the taper ratio. The cross-section area at the driver end is 10x larger than the cross-section at the terminus.
dave
It is a tapered TL. Aperiodic means it is heavily damped. For midrange use the stuffing gets denser as you approach the terminus, with almost none right behind the driver.
10:1 is the taper ratio. The cross-section area at the driver end is 10x larger than the cross-section at the terminus.
dave
Plugged a few numbers in and this is what I got so far for the midTL.
Note: Plots generated from Martin King Worksheets
See Quarter Wavelength Loudspeaker Design
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