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Thread: The Bug is back

  1. #221
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 532
    I'm Sandro.

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    Tanks Martin
    I think that we can bot reply to maximax of the 09/02 (did it really take me that long to glue it on) yes the tube is strong enough no vibration or such from there can't say how much surprised I am

    When the vibration and noise was camming from yesterday was from the glass cabinet and the dog next door when I put the signal generator and set the output at the woofer terminals at 1 watt
    No spelling mistakes one watt 2.86 volts ! most probably rooms modes set in my room being 5 meters in long this is whit the POA4400 at 3 o' clock not as while we were listening whit it at 11

    Frequency response is right down to 10 Hz no spelling mistake

    Disregard the numbers on the picture they are totally meaningless just look at the frequency response ( it will not measure below 10 Hz)DSCF2717.jpg

    the peak at 33 Hz is at the resonant frequency of the pipe it all will be sorted whit a better low pas filter tuned at present at 47 Hz me think

    I sent the faulty woofer away yesterday after a shorth call to the shop they are going to be black listed !!!!


    Main thing is already. I think I have finally found a way to put same punch to the , can stress how much those are the best speakers I have heard now, MG 1.7i.
    No merit of mine here the praise should go to Nelson Pass , you must read the article he posted about the EL Pipe O el-pipe-o.indd (firstwatt.com)

    Al I did was building it, Who said being stubborn is not a virtue ?
    still as I write this I know where I may get a pair of 3.6.

    Yes a 400 W D class be nice and a pair be even betterer another tube behind the telly would make them blend in and disappear like


    WHERE DID I PUT MY HAMMER !!!!!

  2. #222
    Join Date: Nov 2020

    Location: London

    Posts: 15
    I'm Max.

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    I only skimmed the article but the two constructions discussed there differ from yours. Also, did you stuff your pipe? Maybe you can integrate the pipe with your AV furniture, but a much larger TV would also do the trick.
    Why is this pipe better than eg a decent 15 in a closed box? Would an Earl Geddes approach using more conventional subs work with Maggies?

  3. #223
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 532
    I'm Sandro.

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    My front wall view

    DSCF2718[1].jpg


    Hi Max bear whit me...
    At the beginning there was no sound... sorry different forum

    I named this thread the bug is back as it refers to the itch I have to make things This disease went away for a while till Martin and Paul told me that they would like an amplifier like mine
    Big relapse I am afraid

    Me and Martin can't resist the chance of experimenting whit what are already hair rising duck feathers systems plus considering "the current situations" ,this must be the top excuse for time wasting at present, I had plenty of beer money and time to spare

    So Max to answer your question that you are most welcome to ask
    Near the end of the article Nelson write that after blowing 2 of the 4 woofers they just placed them in the pipe whit the magnet of the woofer on the floor supporting the pipe

    Quote:>
    Reconstruction Rather than spend another $800 on woofers, we decided to try single woofers on each side, so we took apart the tubes and reconfigured them as 10 foot tubes with a woofer at the bottom. We made a nice cylindrical coupler out of MDF to mate the woofer to the tube (Figure 19) and sat them on the woofer’s magnet on blocks of granite (Figures 20 and 21). On top of the Fig. 2

    So no stuffing at present because
    1 does it need it ? tube as it is seems to work pretty well
    would it slow down ,and it does as a side effect, the air flow and muddy the sound ?

    I have asked those myself

    So far I have the former material that can be reused again and again I probably have wasted 50 on glue and paper it would have been half of that If one collect old news papers
    Considering this
    Nelson uses 21 in drivers

    Plan was to get 2 15in in Isobaric mode to achieve the same frequency response but reduce the diameter, apart from that length is about the same, awing the telly 16 inches from the wall is ok

    I discovered that one woofer is working pretty well frequency response wise
    directionality is not a problem at such low frequency it would probably be noticed going above 120Hz current filter is at 47 Hz

    Being an hollow round tube there are no resonances from the cabinet, the snag whit it being a transmission line the length of is a function of the frequency response

    I have heard same 5 figures PMC that made me puke by the way

    I can't answer to your question about the Earl Geddes , I am sure Martin could I will do same research on it any way so many tanks for posting
    I have found this Multiple Subwoofer Placement | What's Best Audio and Video Forum. The Best High End Audio Forum on the planet! (whatsbestforum.com)

    Most probably it would cost more than 50 I am budgeting for the glue
    The tubes being suspended seems not to cause any problem whit introducing unwanted vibration
    what would be the effect of one large cabinet? or more ?
    and what about reflections ?
    Next step

    I need to invest same money on the glue I need about 20 litters of it. at this quantity it became a bulk purchase and turns out to be cheaper still apart from that and same old news papers I have all I need including the brackets
    2 tubes will look much better the round shape helps whit diffraction from the wall and 2 of them will blend in much more I was going to do same treatment to it any way and those 2 painting need to be moved away they do deserve a better place
    I am using a Denon POA 4400 as amplifier at present, i got it about 15 years ago for 80

    But I am already building 2 new F5's so the 2 old one's can be used to the subs or to finance the purchase of 2 400W class D that would pay for themselves considering the energy bills

  4. #224
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 532
    I'm Sandro.

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    Just re-reading my post

    Sorry is quite long and I repeat myself

    must be a side effect of the "current situation"



    But hey ! there is method in my madness

  5. #225
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 532
    I'm Sandro.

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    Back to work on the F5T

    I have already made A first prototype of the soft start circuit
    The first interaction was using an Arduino Nano it does work quite well but
    1 There is so much one can do whit the Nano and it would have been wasted
    2 I was wondering about the reliability and noise issues

    So V2 use discrete components

    Here the schematics of the control circuit

    DSCF2723.jpg

    Nothing complicated about it
    Part one of the circuit is a toggle switch circuit


    DSCF2724.jpg

    At start up the Mossfet is off no power flow Led 1 is off
    The only power lowing is a few micro-A due to leakage current
    When pushed the momentary push button toggle the circuit the Mossfet conduct
    Led 1 turn on 5 volts supply is sourced to the 4 cascaded timing circuits



    Timing circuits

    There are 4 cascaded circuits as I am using 4 relays for the 2 800 VA transformers

    As a rule of thumb any Transformer of 300VA or more need a thermistor
    1 to safely size the fuses 2 to stop blowing your mains

    DSCF2725.jpg

    In the picture R27 any from 100K and up charges the capacitor
    Once the voltage is hi enough the NPN transistor causes the PNP transistor to conduct and the Led lights up
    The voltage at point Ref3 make the relay turn on
    Mains power for Transformer 1 is now on
    Ref3 also supply voltage to the resistor that charge the capacitor on the next stage
    Ref4 make the second relay turn on and the thermistor is by-passed
    And so on for Ref5 and Ref 6
    On the drawing:
    the changeover switch is instead a momentary push button no power is present once is pressed and realised

    Led 1 to 5 could be replaced by a single led or omitted I do not really like to have a Christmas tree on the PSU enclosure

  6. #226
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 532
    I'm Sandro.

    Default

    Soft start board


    This is the prototype
    DSCF2727.jpg
    I can make single layer boards easy enough at home

    DSCF2726.jpg


    But a 2-layer job done professionally is much beterer
    Size can be shrunk a fair bit
    From 134X198 I am down to 116X178 and a bit more need sawing off

    On the third picture the first take on the new board
    I will need to place the 18 transistors and 27 resistors on it
    Piece of cake that I will have to swallow tomorrow

    DSCF2728[1].jpg

    I am going to get a few made as the boards are cheaper in larger quantities
    Please PM if you are interested
    It will work whit any amplifier that has one transformer over 300VA or two

  7. #227
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 532
    I'm Sandro.

    Default

    Board done
    Gerber on its way to manufacturer


    DSCF2731.jpg

  8. #228
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 532
    I'm Sandro.

    Default

    The version one of the soft start PCB has landed


    DSCF2736.jpg

    More about this later


    In the mean time the revised matching rig
    DSCF2734.jpg

    I am using a o.1 % 30W 1 Homes resistor
    And a new clamping method

    The old bolt thingy was a pain whit threads stripping after a while and having to use a spanner to tighten up the Mosfet
    The new spring clamp is not only much quicker it also make the clamping force constant so one less chance of errors between one DUT and the next



    DSCF2735.jpg


    It is based on Nelson Pass article "Practical Mosfet Testing for Audio

    The only difference is that the DUT's are measured at a constant temperature

    I am running a first selection of P's and N's channels at 30 V 500 mA and recording the voltage between the gate and the source pin (VGS)

    I am using an arbitrary figure for the current. I recon that 500mA will be the right bias for my heat sinks and it will give me whit 4 + 4 dudas about 4 Amps Class A at the speakers

    This is what I have so far whit another batch on the bench and one on its way

    DSCF2732.jpgDSCF2733.jpg


    Before I pick the 8 P's + 8 N's I need
    There is going to be quite a bit more of matching to do as I am not only looking for matched VGS but also for matched GM

    The P and N channels at the end will not be 100% but I am doing my best besides I have been told, by an Authoritative source quote "You will have to live whit it"
    Please note Authoritative has capital A and is bold underlined as source could not be any higher

    After all this is the 4th F5 I am building. it is taking a long time but I aiming for End game

    To the 23000 views on this thread my tanks for your patience! not long to go now the weather is turning nice and "current situation" be over soon

  9. #229
    Join Date: Mar 2017

    Location: Liverpool

    Posts: 532
    I'm Sandro.

    Default

    Soft start board finished and tested


    DSCF2738.jpg

    Minor mess on the voltage regulator's

    I made a mistake and pins are crossed over the regulator's


    DSCF2741.jpg

    I added same diodes on the Led outputs so that I can use one LED whit 5 large resistors
    One single Blue Led on the front panel that get brighter by stages do me

    Led must be blue in best Pass Lab tradition ,or was it two?

    Any way one can clearly ear the Relays Kicking in one by one

    DSCF2742.jpg


    I have 5 spare boards up for grabs at cost price first came first served
    Send a PM ...

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