Home > 20-40lbs, 3-way, Ribbon, Tower/Floor Standing > Alters to Ibormeith and Latis

Alters to Ibormeith and Latis


High Quality Home Listening Speakers by Bryan Thorne

Speakers in McArdle

Speakers in McArdle

Design Concept

These speakers were designed to be “high-fi” style home listening speakers for my personal enjoyment.  They are intended to provide a rich, detailed listening experience and a wide stereo image for hours of auditory refinement in my bedroom.

Nomenclature

Caer Ibormeith and Latis were Celtic Goddesses prior to the spread of Catholicism.  Latis was the Goddess of water and beer.  Caer Ibormeith was the Goddess of sleep, dreams, and music.  I hope to spend many nights listening to these speakers whilst trapped in the pages of a good book and drifting in and out of my personal reveries accompanied by my favorite archaic beverage.

Drivers

Fountek NeoCD3.0 3″ Ribbon Tweeter: Chosen for it’s clarity and low distortion.  Ribbon tweeters are capable of providing a very accurate and detailed stereo image.  Many previous Transducer Theory students have used them with great success.

Peerless 850518 6.5″ Woofer: This driver was chosen to operate as the midrange woofer in this system.  Peerless drivers are known for their clarity and smooth response.  This driver also extends high enough in the frequency band to make for an easy crossover point at 1.5kHz with the tweeter.  As luck would have it I was able to attain this driver for free.

Peerless 850146 10″ Subwoofer: This subwoofer also bears the Peerless name which came so highly recommended to me by former transducer theory students.  With this driver in a vented box I was able to achieve a strong bass response down to 40Hz.

Enlosure

The box for these speakers was constructed of 11-ply Birch Plywood.  This provided a strong structure and the crossing layers of wood eliminate box resonances.  11-ply was chosen over 13-ply Baltic Birch because of the significantly reduced production costs.  A single layer of the wood was used for the construction to maintain a reasonable weight.  The box was constructed with a 3.5 cubic foot enclosure for the subwoofer with a 3 inch port for a Qtc of 0.54.  The box had a separate sealed enclosure for the midrange driver with a Qtc of 0.7.  The internal walls of the sealed box also doubled as bracing for the larger box.

Crossover

The crossover design for this speaker system evolved into a rather large circuit, but in the end it resulted in an admirable frequency response and a very pleasant sound, so it is well worth it.  The subwoofer has a simple 2nd order low-pass filter on it set around 100Hz.  The midrange driver has a 2nd order high-pass set around 100Hz and a 2nd order low-pass at 1.5kHz.  The midrange also has an L-Pad circuit to bring it inline with the subwoofer made of a 1.5Ohm resistor in line, and a 6.5Ohm resistor in parallel to ground.  A baffle step correction circuit was also added to the midrange.  The tweeter benefits from a 3rd order high-pass filter set slightly higher at 2.5k.  Shifting this point up made for a smoother crossover point and protects the delicate ribbon tweeter from more of the low frequencies.  The tweeter also received an L-Pad circuit to bring it down to the same level as the other drivers.

Measurements

Left Channel Response

Right Channel Response

Left & Right Difference

Group Delay

Impulse Response

Harmonic Distortion

Subwoofer Impedance

Midrange Impedance

Tweeter Impedance

Off Axis Response

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

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  1. F. Bossio
    February 6, 2014 at 12:26 pm

    Are these ribbon 3 way monitors for sale ? Do you build for customers ? thank you

  2. Bryan Thorne
    March 9, 2014 at 7:50 pm

    F. Bossio, Thank you for your interest, but I’m sorry, these speakers are not for sale. Unfortunately, I do not currently have access to the tools or equipment to build speakers.

    • F B
      March 10, 2014 at 4:27 pm

      Thank you for your response.

      F.Bossio

      Date: Mon, 10 Mar 2014 01:06:23 +0000 To: ar250@hotmail.com

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