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Building a 3-way TL speaker

Hari Iyer

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I now have a opportunity to build a 3 way TL speaker for a FM who has a SS Krell ksa100mk2 for bass and TAD 1000 tube mono blocks for mids and highs. Sources are CD-esoteric K-01, DAC - AMR dp-777 and Roon end point for digital streaming - Metrum ambre. Pre-amp is T+A P1260R. Currently they are hooked up with PMC floor standers with Krell amplifier in full range mode. He is in the lookout for more organic and holographic 3D sound stage and flexibility to mix and match various gears with future possibility of going active crossovers. The reason for opting to DIY was to get the best combination of lows, mids and highs with realism which as per him are missing in commercial products at a budget.

With this requirement in mind, i went hunting for various drivers past one+ month and finally narrowed down with Seas Prestige woofers (paper cone), SB Acoustics Satori MR (paper cone) and Beyma AMT (with horns).

The said woofer was selected as i was looking for a more high compliance/ low mass driver that can play the harmonics of the fundamental note quite well without getting compressed. Most high moving mass drivers are low compliance type and they can render only the fundamental bass right and compresses the overtones. This removes all realism from music. Needless to say this driver will be in a exo-linear TL with critical damping and this woofer prefers a lossy line and not a complete sealed enclosure. The Satori will be in a sealed enclosure to benefit of its high compliance (2.35mm/Newton) and i will be using atleast 70% stuffing to give it a high stiffness box for it to perform flawlessly. The tweeters is a AMT type attached to a horn and will be able to perform well at low distortion levels even at lower crossover points.

I have yet to finalize the box sketch as they are still in simulation mode past one month. I have already ordered the drivers and they should be delivered by end of September. This time the carpenter showed some pity for me and shall deliver the box before that. I had also simulated the crossover with publish parameters and they did turn out quite well. But again we will need to build the crossover with measured values and not published ones. Hoping this project to get over by end of this year if all turns out well.

Keep checking this post for updates. Thanks for looking.
 
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Hari Iyer

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Feb 8, 2010
Messages
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Location
Mumbai
Initial plan is to go for a first order crossover for everything. Low, mids and highs. This is one of the major reason to select these drivers. All drivers have a breakup mode 3 octaves above the crossover frequency which currently would be 300Hz and 3KHz. For a first order filters there is a significant overlap of the frequency beyond the crossover points. Hence to get a -6dB response at the crossover point the design frequency need to be either reciprocal of sqrt(2) or multiplied by sqrt(2) to arrive at the design frequency. This avoids the classic hump at the Crossover point and gives a flat response at the passband while still preserving the filter phase at 90deg and eventually cancel out. This gives a response -12 dB down at the next octave. This speaker will be time aligned for the lows, mods and highs so that they integrate well in the time domain. This is the tough part to figure out and design to get the acoustic centers of the drivers integrated so they sound as one. More important for mid to high than the low to mid frequency. Planning to keep the crossover as simple and minimiliast as possible to preserve the SPL of the drivers. Importance will be on accuracy more than frills.
 

sanj

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Aug 26, 2010
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Great..I am also subscribed,kindly let us know expected cost of the end product , i will send you msg for other query.
 
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tcpip

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Mar 1, 2010
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Bombay
Is this Seas woofer the same one which Linkwitz uses for his LX521? I believe it has good low distortion performance at high excursion, which is a rare quality.
 

Hari Iyer

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Feb 8, 2010
Messages
2,873
Points
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Location
Mumbai
Is this Seas woofer the same one which Linkwitz uses for his LX521? I believe it has good low distortion performance at high excursion, which is a rare quality.
tcpip, i believe the LX521 used the SEAS L26RO4Y woofer which is different from the A26RE4 woofer. The A26RE4 is a classic vintage woofer from the mid-70 which was at that time A25 and was extensively used in the Dynaco A-25 classic speaker from the 70s. This speaker requires a lossy line and works well with this kind of loading. Putting them in a TL with some over damping will be suitable imo. Check out the Dynaco A-25 link for more details https://www.stereophile.com/content/dynaco-25-loudspeaker
 
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