iaudio
Well-Known Member
Thanks for the tip on the paper veneer!
My First DIY MLTL Speaker Build
- Thread starter Jaybe
- Start date
Hi Santhosh,
Thanks ! Glad you liked it.
As you may be aware that wood veneers are generally available in 4 mm and 0.5 -0.7 mm thickness. The decorative veneer in both cases is paper thin while the former is bonded to 4 mm Ply and is rigid the later is backed with Paper to give it strength and render it relatively pliant.
Paper Veneer can be formed around gentle raddi and curves but on the other hand faithfully reproduces any flaws in base material. This was the reason I opted for MDF.
Paper Veneer gluing requires considerable experience and patience. Bob had recommended a technique using hot iron for better results. Since the Carpenters were not familiar with the technique and had their own ways of doing it, I gave them leeway. In retrospection, I feel I should have done it myself !
Africa offers most interesting wood species and Zebrano is one of them. Paper Veneer availability is sparse. I was introduced to the MD of a reputed company making high quality Ply and Veneers who gracefully offered to make even one sheet of Veneer of my choice. But I was tired of more wait on an already prolonged project and wanted to wind up quickly so settled for the best readily available.
Cheers!
Jayant
Excellent build and finish. Congrats...
Recollecting from my past experiments with 1st order xovers, all the tweeters I tested performed better with a zobel when the xover point is closer to Fs. So I tend think that for crossover frequencies below 7k, that tweeter might need zobel and possible level matching. Waiting for your listening impressions...
Recollecting from my past experiments with 1st order xovers, all the tweeters I tested performed better with a zobel when the xover point is closer to Fs. So I tend think that for crossover frequencies below 7k, that tweeter might need zobel and possible level matching. Waiting for your listening impressions...
Awesome finish Jayant :clapping:
Hope they sounds as good as they look!
Awaiting your detailed review
Well Done!
Hi Denom,
Thanks !
My listening impressions coming up. Happy so far !
Jayant
I have seen many cross-over designs without the zobel network provided you know the actual impedance of the driver at the cross-over point. You cannot just rely on the data sheet as during production runs these parameters can vary and would not be consistent. If you can somehow measure the actual impedance of the driver at the cross-over point then you can very well design the filter values for this impedance and then the zobel will not be mandatory.
Off-late there are woofers whose SPL are at par with the tweeter or sometimes more than tweeter response. If such is a case then you will need to consider the SPL level matching in the reverse way. Also some designers do not consider the fall in SPL due to the series resistance of the inductors in the woofer stage. If this is not considered in the overall design then there can be a mismatch in the levels. Any mismatch above 1dB in theory is noticed in the response.
Antony,
Thanks !
I did discuss this with the designer who I presume has better insight in to this for these Drivers combination, considering the number of Speakers he builds. His recommendations were to rely on the natural rollover o the woofer and add a capacitor to the tweeter for protection. He did give a circuit which I believe is for Baffle Correction. In his opinion neither an L Pad or Zobel is required for the tweeter. I thought it best to follow it.
While playing the Speakers I do not find the volume at higher frequencies to be rising. For academic interest I do intend to measure the frequency response. So that should reveal the reality.
Cheers!
Jayant
keith_correa
Well-Known Member
This is freakin' good man. Very very good!!!
Can you give more information/details on the machined ports? They are neat.
Can you give more information/details on the machined ports? They are neat.
Jayant,
Thanks for the inputs and first listening impression, I would like to audition your speakers after the drivers are fully broken in.
BTW do you know the crossover frequency of the tweeters?
Keith,
Glad you like the build.
The Port Tubes are machined out of centrifugally cast Nylon Tubes of Black color. This is an over kill ! This material is used for heavy industrial application.
Cheers !
Jayant
Antony,
Franky I don't know the exact crossover frequency. Fostex recommends a capacitor of 1.5 mf in series with the tweeter. Most people use between 0.68 ( Which I have used ) to 1.5 mf.
You are welcome at any mutually convenient time for an audition.
Cheers!
Jayant
keith_correa
Well-Known Member
Overkill is good. If I may ask - how much did you pay for them?
Keith,
This material is a part of the range that my company manufactures. So it does not really cost me anything. If you are keen and have some size in mind, let me know, I will see what can be done.
Cheers!
Jayant
keith_correa
Well-Known Member
Much appreciated, but not at this time. Maybe sometime in the future when I need one - I'll get in touch. Feel free to say "No" at that time
navin advani
Well-Known Member
Absolutely! A jig saw gives you all the accuracy you need.
I thought veneers were about 1mm thick.
Zobels are also used to flatten the rising impedance curves. The way I see it is that the less reactive the loudspeaker impedance is the easier it is to drive.
Yes those ports are beautiful. I too would love to get a few 3" dia ports - with flange the diameter would be maybe 5" or so. Do let us know what they would cost.
Navin,
I have taken the thickness specs. from the manufacturer. If any pieces are lying around, I will measure them.
Some things need to be kept in mind regarding these ports machined from Nylon Tube:
This material has much higher modulus of elasticity than PE and PP which seems to be the material out of which commercially offered Ports are made. These are generally made by injection moulding and hence of fairly low wall thickness. For machined Nylon Port Tubes, optimum wall thickness is about 4-5 mm. Since this is quite rigid, press fitting in to the baffle requires precision machined diameter of the opening. These Port Tubes do not yield as the PE/PP Port Tubes.
When I say Overkill, a Port Tube of 90 mm ID and 100 mm length is capable of supporting a rotating shaft of an industrial equipment with a working load in excess of 12 tons !
Pl. send me a PM with the ID, Collar OD and length of the Ports that you need.
Cheers!
Jayant
GeorgeO
Well-Known Member
Veneer is always thinner than plywood backed decorative ply. It is sliced very thin( since decorative veneers are expensive) sometimes 0.3mm, and is usually paper backed. The best veneer slicing machines are imported ones and can slice timber really thin. Plywood on the other uses lower cost commercial timber, and is generally peeled using a peeling lathe, so it will never give you the "thin-ness" of veneer slicers. Commercial ply veneers are closer or 1 mm thick.
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