keith_correa
Well-Known Member
OT : The term for your TL designs - wasn't it "Advanced TL" before? It's "Advance TL" now.
This time an Advance TL Floor Stander with Dayton Audio Drivers - New
- Thread starter Hari Iyer
- Start date
If you ask me , the most scientific term for this design is Linear TL. "Linear" implies -- straight line without any taper. The term "Advance" is used by many to just term the technology - Some call it advance because of the use of different type of stuffing material which they have patented (PMC). I call it advance as it does not follow the classic TL method of calculating the Line length, cross-section area, stuffing density etc. In the classic TL you design your line near your driver resonance frequency. In this design its much higher than resonance. The line length is much shorter but thicker than a classic TL. Also the stuffing density is much higher in this design. This design allows me practical box designs. A classic TL box usually is too huge for practical implementation.
keith_correa
Well-Known Member
One question: Why the relatively large spacing between the drivers?
For those interested: http://philharmonicaudio.com/ML-TL.html
OK but that is not what I asked.
For those interested: http://philharmonicaudio.com/ML-TL.html
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My room area is just around 160 sqft. I have a door opening to the left and practically a wall to the right. Next there is a shoe rack to the left which needs space to open. Hence practicality scores more over reality. Else i will have to find a different home only for speaker listens. Even this distance of over 6 feet from the rare wall gives me superb image depth, well balanced lows, mids and highs as i get to place the speaker in the mid-field. The mid-woofer is around 6.5" which makes it sound better in the mid-field than the far field. Imo the far field should have driver size above 8"+. The space between the drivers is just 7 feet though it may look more in the image.
keith_correa
Well-Known Member
I asked about the spacing between the drivers not enclosures.
I hv mentioned the science behind them in my very first post. Pls check and get back to me if you did not follow
And now for the measurements ---
The final simulated frequency response, Impedancce and phase of the Dayton Audio speaker system after accounting for component tolerances
The measured impedance and Phase of the completed Speaker System - You can observe that the simulated and measured response is within 2% of tolerances of each other. The system line tuning frequency is at 50Hz.
The measured frequency response and impedance is very close to the simulated response
The Unit Step response indicate an excellent integration between woofer and tweeters with very smooth decay
The Impulse response show that the tweeter polarity is connected reverse. Also the rigidity of the cabinet walls and damping is clean.
The decay shows a very even decay across the spectrum with overhang at around 74Hz due to room anomolies. This needs to be corrected by adding some kind of bass trap at the rear or the front wall.
The Waterfall plot indicates smooth even response for the entire audio spectrum with some energy at 74Hz due to room interaction which needs to be tamed.
The Spectrogram indicates some energy at 35Hz (which is the lowest FR of this speaker system), some additional energy at 74Hz and at 3rd harmonics (150Hz) and 5th (250Hz) harmonics of the line tuning frequency(50Hz). May be some additional stuffing could help here.
Any FMs keen for a listen and want to discover how a phase coherent speaker sounds and also know what all the fuss about measurements is all about are welcomed this weekend for a listen after PM to me. Will be delivered to customer next week as i dont anticipate any tweaks.
Associated Equipments:
Marantz cd5400: Entry level CD player - I have modified the low pass filter with an audiophile op-amp. Also have replaced all electrolytic capacitors in the signal path with non-polar types of the same value.
Pre-amplifier: This is a class A preamp using audiophile IC LM4562 with a gain of 10dB. The output stage uses a DCB1 buffer with the details provided by FM Omishra.
Power Amplifier - Dared VP-300B mono-blocks (6 watts + 6 watts). This amplifier is a bit under powered for the speaker which has an calculated SPL of 86dB and a measured SPL of 86.1dB. Again the SPL is quite good if the volume knob is over 1 o'clock position.
Other source:
Technics SL23 - Belt drive TT
Nakamachi Bx100E - Tape deck
Yes I am an analgoue guy and enjoy my Vinyls and Tapes more than my CD collections.
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keith_correa
Well-Known Member
Oh, I'd seen that:
I just didn't understand what it meant by reading it. Can you explain?
Convert 1800Hz to its wavelength. WL = c/f. Where c is the speed of sound in meters ie. 343.2 m/sec and f is the crossover frequency. That will be 7.5".
This is the distance between the woofer and tweeter center point. This will allow the woofer and tweeter to work like a single driver and not two point source.
Yes they are phase coherent from acoustic point of view as there cannot be any time shift (delay) between them in propogation.
Electrically there still can be a phase error due to the SPL phase and Impedance phase not being in sync. The SPL phase and impedance phase in a full-range driver still need to bisect at 0 deg for complete phase coherence else phase error can be noticed imo.
In a full range driver due to the voice coil inductance the load become more inductive due to the self inductance of the voice coil as frequency increasesi. This needs to be compensated for to make the load more resistive.
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keith_correa
Well-Known Member
I thought that the ROT is the maximum CTC needed and that closer is ALWAYS better. No?
Edit: And I was also under the impression that because the SOS is variant, closer is better than a ROT.
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Depends upon your design philosophy, if you like it that way keep them.
SOS will be exactly identical with my method with no cancellation of common frequencies. Also ROT will be accurate as at crossover WL of both woofer and tweeter is identical.
SOS will be exactly identical with my method with no cancellation of common frequencies. Also ROT will be accurate as at crossover WL of both woofer and tweeter is identical.
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keith_correa
Well-Known Member
I thought the SoS depended on the temperature of the air and altitude. But I'm nitpicking.
I am aware of my room temp and altitude, but dont know its implementation.
kapvin
Well-Known Member
Hello Hari,
Congratulations on using such good drivers. These are unique where they couple amazing low distortion int he passband at a really low price. they are pretty much the stars of the dayton range in price / performance
One question - Is this advance TL the same single stuffed line design that you were using earlier. or is it something different.
Some points that you would want to explore.
the dayton 7" (RS180) has a terrible breakup mode at 9khz (with break ups starting at 3khz). using it as a 2way with 1st order crossover is extremely inadvisable as the sound will be extremely fatiguing. you need to push the break up point down below the point of audibility (-40db below signal is a good indicator) to ensure a smooth sound. if you want to use a first order network, almost always, avoid an aluminium driver. luckily the Dayton Alumimium tweeter is extremely stable upto 1.2khz as long as used with a high order high pass. Please google Jon Marsh's Modula to get a sense of the complex crossover required to make these drivers work well together in a 2 way. for my bookshelves with with exactly the same drivers, i used a second order electrical crossover with a notch at 1.3khz. (slope was effectively more than 3rd order)
the other point with first order is the uneven frequency response caused by driver overlap over a larger frequency range.
finally if you are making this for your own room, which is small and has a lot of bass gain, you probably do not need BSC, but if you are planning to commercialise it and build for others, you should incorporated BSC, otherwise weak bass will be a bit of a problem.
woodwork looks good..
cheers
its dependent on density of air which is dependent, as you correctly pointed out, on temperature and altitude.
at sea level the difference in the speed of sound between 20c and 40c is 9ms/ or about 3%.
while determining the appropriateness of tuning (of line length) other factors will play an equal or bigger role (including shift in T/s parameters as the Voice coil heats up)
edit: as far as crossover is concerned, you are right, minimal CTC is always best especially for lower order crossovers, not because of speed of sound variation, but because of lobing that comes out of driver interaction beyond crossover point. for eg. in this first order crossover, the woofer will only be -6db down, at 3.6khz, which is enough to cause interaction and lobing issues. coupled with the rising response of the Rs180 beyond 2k (as the first break up at 3+khz) there is literally no attenuation at 3.6khz.
hope that clarifies
Congratulations on using such good drivers. These are unique where they couple amazing low distortion int he passband at a really low price. they are pretty much the stars of the dayton range in price / performance
One question - Is this advance TL the same single stuffed line design that you were using earlier. or is it something different.
Some points that you would want to explore.
the dayton 7" (RS180) has a terrible breakup mode at 9khz (with break ups starting at 3khz). using it as a 2way with 1st order crossover is extremely inadvisable as the sound will be extremely fatiguing. you need to push the break up point down below the point of audibility (-40db below signal is a good indicator) to ensure a smooth sound. if you want to use a first order network, almost always, avoid an aluminium driver. luckily the Dayton Alumimium tweeter is extremely stable upto 1.2khz as long as used with a high order high pass. Please google Jon Marsh's Modula to get a sense of the complex crossover required to make these drivers work well together in a 2 way. for my bookshelves with with exactly the same drivers, i used a second order electrical crossover with a notch at 1.3khz. (slope was effectively more than 3rd order)
the other point with first order is the uneven frequency response caused by driver overlap over a larger frequency range.
finally if you are making this for your own room, which is small and has a lot of bass gain, you probably do not need BSC, but if you are planning to commercialise it and build for others, you should incorporated BSC, otherwise weak bass will be a bit of a problem.
woodwork looks good..
cheers
its dependent on density of air which is dependent, as you correctly pointed out, on temperature and altitude.
at sea level the difference in the speed of sound between 20c and 40c is 9ms/ or about 3%.
while determining the appropriateness of tuning (of line length) other factors will play an equal or bigger role (including shift in T/s parameters as the Voice coil heats up)
edit: as far as crossover is concerned, you are right, minimal CTC is always best especially for lower order crossovers, not because of speed of sound variation, but because of lobing that comes out of driver interaction beyond crossover point. for eg. in this first order crossover, the woofer will only be -6db down, at 3.6khz, which is enough to cause interaction and lobing issues. coupled with the rising response of the Rs180 beyond 2k (as the first break up at 3+khz) there is literally no attenuation at 3.6khz.
hope that clarifies
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Thanks for your excellent inputs. Appreciated.
The TL box is still using the same design which i have used before - tune higher than resonance, heavily stuffed.
The first order crossover uses a sollen type network where at the crossover point the response is -6dB than the normal -3dB response. This helps in avoiding the +3dB peak at the crossover point and gives a flat response. Actually the woofer is crossed at 1148Hz and tweeter at 3330Hz to achieve this flat response at crossover.
If you refer to the simulated response in the first post, the response of the woofer at 9KHz is around 53dB which is 33dB down from 86dB. This is more of a non-textbook response where the woofer roll-off is @ of -10dB per octave and the tweeter roll-off @ of -7dB per octave. I am not able to listen any resonance mode breakup at my initial listening test. Maybe my ears are not trained for this. I have not used any BSC as the room where this drivers are installed is standard around 200 sq.ft. Infact the low frequency lift is more than i expected though not boomy.
Will check the articles as suggested by you and try to analyze if i am able to.
Thanks once again.
kapvin
Well-Known Member
thats great. if you are happy.
Like I said in my edit.. i used exactly the same drivers in my bookshelves which I use as surrounds. let me see if I can find the distortion measurements with various crossover options. will email them to you.it might help explain better why I made the design choices I did.
it might be worthwhile to explore a higher order crossover.
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keith_correa
Well-Known Member
@Kapvin,
I reviewed this link http://www.htguide.com/forum/showthread.php?13154-RS180-Modula-MT-you-asked-for-it-you-got-it! and reviewed the content. I could not analyze the circuit as it being non-standard and have used many topologies for the design. Ironically the crossover freq used is still the same. I have not measured with reverse connecting the tweeter in my setup which would have verified my crossover freq accuracy. Both the impedance and its phase is different and hence both speakers will sound a bit different.
The distortion graph as measured in my room for the Daytons
Top - Fundamental, Black - THD - 5.08% , Red - 3rd Harmonic - 0.929%
I reviewed this link http://www.htguide.com/forum/showthread.php?13154-RS180-Modula-MT-you-asked-for-it-you-got-it! and reviewed the content. I could not analyze the circuit as it being non-standard and have used many topologies for the design. Ironically the crossover freq used is still the same. I have not measured with reverse connecting the tweeter in my setup which would have verified my crossover freq accuracy. Both the impedance and its phase is different and hence both speakers will sound a bit different.
The distortion graph as measured in my room for the Daytons
Top - Fundamental, Black - THD - 5.08% , Red - 3rd Harmonic - 0.929%
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