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Thread: TAD 2404 Build

  1. #31
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    Quote Originally Posted by Dr.db View Post
    First of all, sorry for asking these things again, I hope I donīt misuse this thread!



    So the formula didnīt take the three inductances into account, right? So the 28hz tuning is without the crossover and in reality tuning frequency will raise from 28hz to 32hz because of the resistance of the inductors?
    If I run the woofer without the passive crossover, I would have to shorten the ports a bit to reach a 32hz tuning, right?

    .

    Sorry if I might mix up on things, but the thread-starter used a volume of 171 liters in the formula rather than your 135 liters.
    Thatīs why he gets 28hz tuning and you get 32hz tuning with the same port-length?
    Or does the 2404 enclosure uses a different woofer-type?

    .

    Iīve looked at this page for the specs on the TAD woofers:
    http://www.technicalaudiodevices.com/lf-units
    QTS is 0,34 for TL-1601a and TL-1603, but is 0,31 for TL-1601b. FS and VAS is very similar on all of them.
    Thatīs why I was thinking 1603 is closer to 1601a than to 1601b...

    Btw; can I simply copy the value of the End correction factor or how do I determine this figure for the formula for the 1603 ?

    .

    Subtracting the panel thickness of 22mm from the outside dimension, I get 202,5 liters for the internal volume for the 2402 enclosure. Of course bracing, driver displacement and midrange-horn displacement has to be subtracted of that 202,5 liters, but my guess wouldīve been this could result in 20-30 liters. To result in a netvolume of ~130 liters the insides must occupy nearly 70 liters! Is the 2402 braced that heavily?
    Donīt get me wrong, I do not want to argue with you or doubt knowledge as you have build a copy yourself, I just want to understand.


    You are right, I forgot the resistance of the coils (around 0.6 ohm in TN-2 network). This is lowering the Fb value repectively to the port length. This is meaning port has to be shorter than the computed value.

    There should be something wrong as TS of 1603 are the same as the ones for 1601b (same cone, and magnetic field), while 1601c as used in Exclusive 2404 has similar TS as the 1601a

    TL-1601a/b/c takes about 6L of volume. TH-4001/TD-4001 takes about 30L, Bracing parts are huge with 44x60mm sections

  2. #32
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    Thanks a lot!

  3. #33
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    Hi ,

    you can't compare 04 and 02 ... 4003 and 4001 aren't the same to start with. 1.5" and 2" respectively . The 2404 use 1601c woofers ... and yes ,more like the A TS than the others .

    My internal volume 183 ltrs subtract 12 for 1601,horn and bracing left me 171 .... there is more bracing in my copy, as that was an issue with the original . There is also no 18mm MDF in my build on 25mm BBP . The final tuning is spot on , more by luck than judgement . I have made a few changes . I never intended to build an exact copy, only that they were in the spirit of the original . These small changes were to get around copyright issues . And yes , I'll build another pair in the future and run them actively .


    Richard .

  4. #34
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    Quote Originally Posted by richluvsound View Post
    Hi ,

    you can't compare 04 and 02 ... 4003 and 4001 aren't the same to start with. 1.5" and 2" respectively . The 2404 use 1601c woofers ... and yes ,more like the A TS than the others .

    My internal volume 183 ltrs subtract 12 for 1601,horn and bracing left me 171 .... there is more bracing in my copy, as that was an issue with the original . There is also no 18mm MDF in my build on 25mm BBP . The final tuning is spot on , more by luck than judgement . I have made a few changes . I never intended to build an exact copy, only that they were in the spirit of the original . These small changes were to get around copyright issues . And yes , I'll build another pair in the future and run them actively .


    Richard .
    I thought these 2404 were in Iceland, are they in London ? If yes I'll send you a PM, I'm free this evening to listen to them

  5. #35
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    Quote Originally Posted by richluvsound View Post
    Hi ,

    you can't compare 04 and 02 ... 4003 and 4001 aren't the same to start with. 1.5" and 2" respectively . The 2404 use 1601c woofers ... and yes ,more like the A TS than the others .

    My internal volume 183 ltrs subtract 12 for 1601,horn and bracing left me 171 .... there is more bracing in my copy, as that was an issue with the original . There is also no 18mm MDF in my build on 25mm BBP . The final tuning is spot on , more by luck than judgement . I have made a few changes . I never intended to build an exact copy, only that they were in the spirit of the original . These small changes were to get around copyright issues . And yes , I'll build another pair in the future and run them actively .


    Richard .
    To go active is the best route with these TAD loudspeakers. I did this on my 2402 clones, and will never come back.
    If you can, mesure the frequency response at the output of the passive crossover and clone them in a digital crossover. This is what I did with a TN-2 network.

  6. #36
    Senior Member richluvsound's Avatar
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    New Diaphragms ...

    I'm waiting for new diaphragms .... hopefully they'll be hear new week .

    Richard

  7. #37
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    Then next time I'll be in London, if not sold before

  8. #38
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    Quote Originally Posted by richluvsound View Post
    The final tuning is spot on , more by luck than judgement . I have made a few changes .
    What is your final port length in your enclosures?

  9. #39
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    Port length

    Quote Originally Posted by Dr.db View Post
    What is your final port length in your enclosures?

    10.001 cm or 100 cm

    R

  10. #40
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    Can you explain from where your port end correction factor is coming from as it is far from the usual 0.783 used in simulation software, while providing tangible results for these TAD speakers

  11. #41
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    Quote Originally Posted by dn92 View Post
    Can you explain from where your port end correction factor is coming from as it is far from the usual 0.783 used in simulation software, while providing tangible results for these TAD speakers

    I used this calculator .... http://www.calculatoredge.com/new/ventlength.htm

    Tangible results meaning what ?

  12. #42
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    Quote Originally Posted by dn92 View Post
    Can you explain from where your port end correction factor is coming from as it is far from the usual 0.783 used in simulation software, while providing tangible results for these TAD speakers

    Hold on ... why am I feeling like I have something to prove to you ? What simulation software are you using ..... ? what info did you put in to get that figure ? What is your point of reference ? what TAD components are you measuring ?

    R

  13. #43
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    Quote Originally Posted by richluvsound View Post
    Hold on ... why am I feeling like I have something to prove to you ? What simulation software are you using ..... ? what info did you put in to get that figure ? What is your point of reference ? what TAD components are you measuring ?

    R
    You are misunderstanding, I'm not doing any criticism.

    I had already found the online calculator you used. In the picture you posted there is a correction factor you choose as by default there is nothing in the calculator. I just want to know why you used this one and from where it is coming.

    I'm usually using WinISD that gives different results than your calculation due to a different correction factor. The correction factor you used allows prediction and reality to closely match for my TAD 2402
    clones. Therefore I've interest in understanding.

  14. #44
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    All in good fun DN .... note the that software does everything ... . what components are you using in your clone ?

    Rich

  15. #45
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    TAD units of course (TL-1601a and TD-4001 on an IWT TH-4001 horn), otherwise it is not a TAD 2402 clone but another loudspeaker.

    In case this can be usefull for someone (At least for Dr dB):

    I decided to do again the calculation of the internal volume, and I don't know why I did it wrong the first time.

    Raw volume 200L (22mm panels, and considers volume taken by the space behind the crossover plate).
    Calculated Vb=155L
    Bracing takes 20L
    Horn takes 10L (approximation made to two trapezium/trapezoid, and taking into account the horn round/rectangular adaptation piece)
    Woofer takes 6L
    TD-4001 takes 3L
    BR tubes takes 1L
    The rest is taken by cables and passive crossover .

    Using a port end correction factor of 0.846 (Jorg Panzer) and considering that there is a port coupling effect (K becomes 0.954), that damping increases Vb by 33% (more than the traditional 20% given by books), I got a port length of 105.04mm.

    A bit of lecture illustrating differences between practice and theory for this subject: http://www.troelsgravesen.dk/vent_tuning.htm
    Troel is considering in practice that port length is around 0.6 of the computed length, using Vb value not augmented by considering damping material effect.

    With WinISD computed length for 100mm BR tubes, with K=0.732, applying this 0.6 factor, the result is 115mm. A bit too long in practice for Fb=32Hz. Originally I used tubes of 120mm length and got (from impedance measurements) 30Hz for Fb, a bit too low (targeted Fb=32Hz). My correction factor given from my experimental results would be 0.54.

    Applying this to 171L volume and targetting Fb=32Hz, Troel's approximation with 0.6 correction factor gives 100mm length for two tubes of 100mm diameter. Applying 0.54 correction factor for tube length, it gives a length of 91mm.

    In practice what I do for tube length adjustment, is to cut the ports at a length I consider to be too much and then using impedance measurements to get the real Fb. Then I use the theoretical formula to determine the proportionality in terms of length between the actual and targeted length. There is just to cut the ports to the obtained length.

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