Transmission Line Speaker Build by me - My second project

Hari Iyer

Hari Iyer

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Hello All,
Photographs of my first Transmission Line speaker system some details below,


Woofer - 6.5" Peerless Kevelar cone for tight bass and smoother mid-range (wide range drivers). Has a reasonable flat response till 5KHz after which roll-off begins. There is a small un-even response between 180Hz to 500Hz (+/-2dB) and between 1KHz to 2.8KHz(+/-4dB). Used some response shaping circuits for these driver anomolies.

Tweeter - 1" Low Fs Peerless Aluminium Dome for smooth and mellow highs (wide range drivers). Has a rising response from 2KHz till 20KHz (+/-3dB). Used some response shaping circuits for these drivers from 3KHz till 20KHz.

Enclosure Type - Transmission Line with traingular wave guides, Time aligned enclosure (coherent sound stage) and diffraction corrected.

Tuning frequency - 34Hz (Quarter wave length)

Frequency Response (-6dB) - 19Hz to 22KHz

Sensitivity - 91dB/w/m

Cross-over - 1st order zero phase shift Butterworth cross-over network, zobel correction, L-pad, parallel and series notch, contour circuits and Baffel step compensators.

Nominal Power - 150 Watts

Nominal Impedance - 6 ohms

Cross-over frequency - 3000Hz (1st Order)

Features:

- Guided wave Transmission Line enclsoure ensure no boomy bass stimulating atmosphere of live performance and extended dynamics
-Wide range drivers ensure optimum performance in the enitre frequency band-width of the speaker system
-1st order filter, time alignment and diffraction compensation on the baffel ensures Excellent on & off- axis response
-Harmonics balanced to ensure real life performance of music and vocals
-Zero phase-shift 1st order Butterworth filter ensures excellent transient response without ringing/ ripple effect and faster settling times for the filter due to fewer passive components
- Cross-over of 3000Hz is more than 3 octaves above the resonating frequency of the tweeter (672Hz). Lower cross-over design helps in preventing cone break-up for tweeters at higher volumes. Also wide frequency response of the woofer allows cross-over at 3KHz there by preventing inter-modutlation distortion. Transmission line design helps in very smooth and balanced mid-range allowing flat impedance range for the entire operating range of the woofer. This allows in better power transfer between amplifier and speaker allowing low vibration of the woofer cone improving sonic performance. There are a total of 15 passive components in the cross-over including 2 actual cross-over filter components.
 
Last edited:
CANDUU said:
Wishes on ur diy,did I miss something?Where is the photographs mate?
Click to expand...

Sorry guys, this is my first new post in Hifivision. Hence was learning how to post photographs. Have uploaded the photographs. Pls. post your views.

Kind Regards,
Hari.
 
It would be more informative to our fellow forum members if u provide the price and from where u purchased the drivers mate ,how much it took to complete this wonderful diy,it would personally helpful for me because i am in to it ,searching for the drivers.
 
Very nice! What are the dimensions? Can you post a pic of the back? What's a triangular wave guide? Did you measure the drivers? Where did you buy the drivers from? What did it cost you? What did you use to calculate the line? Most importantly, how does it sound?
 
Anil kumar said:
Congratulations !!!! looks neat.
Where did you get 6.5" Peerless drivers?


Regards,
Anil
Click to expand...

The peerless driver was with me for the past 3 years and i built the system about a month ago. Was doing research for the past 3 years for the best enclosure system and cross-over for all these years and then arrived at this design.
 
keith_correa said:
Very nice! What are the dimensions? Can you post a pic of the back? What's a triangular wave guide? Did you measure the drivers? Where did you buy the drivers from? What did it cost you? What did you use to calculate the line? Most importantly, how does it sound?
Click to expand...

Will measure the dimensions and post the pic of the back tomorrow. I did not measure the driver as i was having the TS parameter of the drivers with me (Courtesy Peerless India- Mumbai). All the specifications in the post are calculated values and not measured. The drivers were brought from Peerless Dealers at Ghatkopar, Mumbai. The 6.5" driver 3 years ago costed me Rs.1400/- and the alunimum dome tweeter 6 months ago costed me Rs.1000/-. The entire speaker system costed me around Rs.23,500/- including material and labour. I used my research and excel with formulas to calculate the length of the transmission line. It uses variable damping at different lenghts to damp the odd-harmonics. Typically transmission lines are build using rectangular wave guides, triangular wave guides have the added advantage that the sound from the rare of the woofer does not bounce back to the woofer as the reflections from the back-wall of the enclosure is absent due to triangular wave guide.
I would say the sound compares to PSB-stratus Gold loudspeaker system if you have heard it and sounds better than the KEF systems as auditioned by some of my friends here at Thane.
 
CANDUU said:
It would be more informative to our fellow forum members if u provide the price and from where u purchased the drivers mate ,how much it took to complete this wonderful diy,it would personally helpful for me because i am in to it ,searching for the drivers.
Click to expand...

The Peerless 6.5" drivers are currently out of stock (i feel extremely sad about this as they are excellent drivers) and i had bought it for Rs.1400/- 3 years ago from Peerless Dealers at Ghatkopar, Mumbai. The peerless 5.25" kevelar drivers are currently available (Resonating Freq = 57Hz, Max power=300 Watts). It took more time to design rather than built it. I was researching almost for 3 years and it took just 15 days to built it (i took help of a local carpenter). The cross-over design took almost a month and to built the cross-over another 2 weeks as i needed to wind the inductor and look for Polyster capacitors and carbon resistors.
 
keith_correa said:
If I remember correctly, forum member tcpip had measured these 6.5 kevlars for his Asawari's.
Click to expand...

Hi Keith
Even I think they are the same drivers which Tarunji used in his DIY project

I think the drivers are out of stock since quiet some time


@ Hari, Speakers look good and I am sure they sound equally well
 
Hari, would it be possible for you to draw up a sketch of the innards? I'd like to know what a triangular wave guide is. Alternatively, if you could point me to some website that describes this...
 
HI Hari Iyer,

Great looking speakers, Simple on the outside, complex from the inside to make and design, I would love to look at the basic design inside (May be a sketch?) and some more enclosure detailing etc? All my questions have already been asked by our friends in the forum,

To use one word to describe your speakers "WOWWWWW"

With Regards

Vinod Ranganathan
 
keith_correa said:
Hari, would it be possible for you to draw up a sketch of the innards? I'd like to know what a triangular wave guide is. Alternatively, if you could point me to some website that describes this...
Click to expand...

I will try and draw the sketches of these by the next week as i am a little bit held up due to some medical emergency in my family. There are no information related to triangular wave guides but it is just a wave guide like a rectangular wave guide. Since the inside pipe forms a shape of a triangle i have called it a triangular wave guide. This helps in preventing the rare wave of the woofer from channelling downward instead of reflecting back on the woofer. Also standing waves are not present in the 1st pipe due absence of the back wall. I have used 2Sd area for the 1st pipe and 1Sd area for the 2nd and 3rd pipe. The total pipe length is 96 inches and hence tunes to around 34Hz. The resonating freq. of the kevlar woofer is 38Hz. The calculated lowest octaves will be 19Hz @ -6dB reference. (1 half-octave response below the resonating freq of the woofer). This design uses a straight line pipe and is not mass-loaded. The terminus is also = 1Sd area. The damping used is varing damping in the 1st pipe to damp the odd harmonics and moderate to little damping in the 2nd pipe and very little damping in the 3rd pipe. I had to do some adjustment of the damping to tame the mid-range response emering from the terminus and adjust for the perfect bass response. It took me around 2 weeks to adjust the damping and further 2 week to adujst the baffle step resistor after listening test and feedback from friends.
 
captrajesh said:
Hi Hari Iyer,

Great to see the effort of DIYers. Nice looking speakers. BTW could you eloborate the above.:)

Rgds


Rajesh
Click to expand...

There woofer and tweeter had some non-linear response in the pass frequency band which needed adjustment to avoid high and low Q-points in the pass-band of the speaker. I used simulated parallel noth filters to make the response of the woofer & tweeter as flat as possible. You can find this in this link http://www.mh-audio.nl/parallelnotchfilter.asp. This simulator helps you view the frequency-domain plot of the woofer/Tweeter (you should have this from the speaker supplier) and helps you to adjust the response of the speaker by attenuating the response at a particular frequency poing. You still will have to use manual judgment but is good tool to start.
 
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