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  1. Old Comment
    abraxalito's Avatar

    Revisiting active speakers - HiVi D1010

    Yes - with the back open the port (a rectangular arrangement at the top) is bypassed. But no fan effect as the fins of the heatsink aren't positioned to encounter any air movement. Making the port out of aluminimum and putting the chips on the outside of that might be a solution. Far easier though to go classD....
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    Posted Yesterday at 05:53 AM by abraxalito abraxalito is online now
  2. Old Comment
    fas42's Avatar

    Revisiting active speakers - HiVi D1010

    So the electronics are within the bass reflex cavity - is the concept perhaps that the harder the speaker is working the more air moves around internally, that the bass driver is effectively working like a fan?

    Edit: along those lines it would be interesting to run a thermocouple inside and attach to the heatsink, see how it varies with power levels, and level of bass content.
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    Posted Yesterday at 05:17 AM by fas42 fas42 is offline
    Updated Yesterday at 05:20 AM by fas42
  3. Old Comment
    abraxalito's Avatar

    Revisiting active speakers - HiVi D1010

    With the backplate open, bass sufferes a fair bit. I haven't much tried things at high level because even with no signal the heatsink's too hot to touch for more than a couple of seconds.

    I think the best solution would be to replace the internal spacer with something thermally conductive, to let heat excape to the back panel. Incidentally the pic I've included doesn't accurately reflect the model I have - mine has the heatsink further from the back panel (by 1cm or so). Not sure why they did that.....
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    Posted Yesterday at 04:16 AM by abraxalito abraxalito is online now
    Updated Yesterday at 04:19 AM by abraxalito
  4. Old Comment
    fas42's Avatar

    Revisiting active speakers - HiVi D1010

    Re the heatsink very hot, have you tried running them at high levels with the back plate not fully pushed in, say 1/2" gap - not screwed into place should not change the driver behaviour, should it? Would get a funnel effect dissipating heat, does it sound better when the chips are not thermally stressed?

    If a positive there, you could butcher the case, drill and jigjaw holes to provide venting ...
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    Posted Yesterday at 03:19 AM by fas42 fas42 is offline
  5. Old Comment
    fas42's Avatar

    Revisiting active speakers - HiVi D1010

    I put it down mainly to laziness - they don't want their world view to be complicated by new "evidence" possibly disrupting long held views; the easiest course of action is to shout down the "interlopers", hoping that will scare them away, and thereby leave the old guard to peacefully ruminate under a tree ...
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    Posted Yesterday at 03:02 AM by fas42 fas42 is offline
  6. Old Comment
    abraxalito's Avatar

    Revisiting active speakers - HiVi D1010



    I've never understood this stick that's used by objectivists that 'no-one will take you seriously if you don't (fill in objectivist shibboleth of your choice here)'.

    Why would I care if people don't take me seriously? Its their loss if I'm on to something and they choose to ignore me....
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    Posted Yesterday at 02:21 AM by abraxalito abraxalito is online now
  7. Old Comment
    fas42's Avatar

    Revisiting active speakers - HiVi D1010

    No wincing allowed, Richard - definitely a no-no in this audio game ... of course, you would have to statistically prove that you were wincing, for anyone to take you seriously ...
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    Posted Yesterday at 12:33 AM by fas42 fas42 is offline
  8. Old Comment
    fas42's Avatar

    Revisiting active speakers - HiVi D1010

    Nice effort there, Richard ...
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    Posted 21st September 2014 at 01:20 AM by fas42 fas42 is offline
  9. Old Comment
    peranders's Avatar

    Super Regulator PCB's for free

    Boards are available. Send me a message.
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    Posted 9th September 2014 at 01:10 PM by peranders peranders is offline
  10. Old Comment

    Simple DSP Crossover implemented using PIC32MX450

    Quote:
    Originally Posted by mbates14 View Comment
    Is there a way instead of driving a DAC, use a PWM signal output? Reason I ask it would be neat to drive a Class-D output stage directly from the DSP. Technically since the DSP is doing all the audio processing anyway, instead of taking final processed output and sending it I2S, use a timer to generate a PWM from the same data? Also unless I am missing something, I dont see a link for the code.
    An interesting thought - I have not thought much about this...

    The PICs are floating in timers and PWM generators. Without thinking too hard about it, I have no doubt that the PIC32 would make a "fair go" at driving a class D output stage.

    The rub will be "How good a job will it do?".

    The software knows would be able to update the hardware PWM / Timer system at the sample rate quite easily. I wonder if anybody has looked at this.
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    Posted 6th September 2014 at 01:44 PM by googlyone googlyone is offline
  11. Old Comment
    jan.didden's Avatar

    Superregs for your line-level projects

    Hi David, yes the change in the zeners in series with the output are meant to put the opamp output smack in the middle of its supply for optimum performance. Similarly with the change of the ref to 10 or 12 V which would place the inputs in the mid-supply range (and yes that means you'd need to modify the feedback resistances).
    But this is more my personal obsession with splitting hairs - as you found out, this circuit is pretty robust and works quite well as-is. Don't bother to make any changes now that you have it up and running!

    Jan
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    Posted 1st September 2014 at 07:47 PM by jan.didden jan.didden is offline
  12. Old Comment

    Superregs for your line-level projects

    super-reg +/-24v

    Jan,

    I got the boards running at +/-24v, with the published values for the schematic, the only modifications was for the resistor pairs that give the 24 volt output, and the more robust 35v caps.

    I think i understand the suggestion to change the zener from 6.8v to a 12volt zener but i want to make sure, you are talking about D2 & D7 from your schematic? I tried this and the output didn't change, I am assuming it sets up the circuit to operate in its optimum range?

    Are you also suggesting to change D5 & D10 to a 10volt diode? I tried this and it requires reconfiguring the resistor pairs to get the target output, I am not sure if this results in 'better' performance.

    I don't have a scope to see the effects of these changes, so any advice you can lend will be helpful.

    Thanks so much for your assistance etc.

    David
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    Posted 1st September 2014 at 06:16 PM by anystereo anystereo is offline
  13. Old Comment
    abraxalito's Avatar

    DAC filter for discrete buffer

    From Eldam:

    The fastron does not needs matching : the 5% precision is enough with your new design ?

    ...do you think it can add a big plus with a TDA1541 or TDA1387 before a i/V la SEN ?


    I think the Fastron inductors are in reality 10% and no, they are close enough (I think) that they don't need to be selected.

    About TDA1541 I think this filter won't be suitable as the output voltage will be too high. The TDA1541 has too low compliance, but the filter could be used with some additional matching resistors. Also the filter can't be used before an I/V resistor, its a voltage filter, not a current filter.
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    Posted 30th August 2014 at 12:40 PM by abraxalito abraxalito is online now
  14. Old Comment
    fas42's Avatar

    Doing interesting things with electronic keyboards

    I need a good laugh every now and again ...

    I'm learning to mangle MIDI files - the raw source that makes keyboards dance to the tune - so that they actually do what you want them to do - so I looked at a couple of programs, not particularly impressed so far. So, looking around I found this, Decent, free, open-source MIDI editor for Windows: Sekaiju! - Forums, and it made my day, - it reminds me of my experiences with Audio DiffMaker, .
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    Posted 30th August 2014 at 05:31 AM by fas42 fas42 is offline
  15. Old Comment
    fas42's Avatar

    2,000W into 1 ohm

    A separate box is good, and bad. Good, because it keeps some of the nasties away from the amplifying circuitry; but bad because it means that further filtering, regulation is required inside the amplifier boxes to prevent significant voltage fluctuations, caused by current transients through the impedance of the umbilical cord - that cord should be the lowest resistance, lowest inductance, highest capacitance type you can devise, for that reason ...

    The 'goto' thread, IMO, is here: http://www.diyaudio.com/forums/power...voir-size.html - a huge amount of very useful input, and wrangling about what's important, and why. In there is good discussion of ways to "measure" transformers.

    Note that there are a lot of people in diyAudio with very extensive, hands on experience with what devices are best to use in various areas - I don't have anywhere near that sort of experience; my approach is to start with a target performance, and use what's needed, that's easily available, to give me that - I don't do casual experimenting, if it works it works. In other words, I don't like to give advice on the 'right' part to use; I work from the angle of a troubleshooter, rather than a designer.

    Regulation is good, but the power you're dealing with is great - a smart design will be needed be to it make happen efficiently.

    Hope this helps a bit !!
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    Posted 29th August 2014 at 11:10 PM by fas42 fas42 is offline
  16. Old Comment

    2,000W into 1 ohm

    Noted. I had the krill and Aleph-X in mind for this supply but since it will remain in a separate box, I'd like to use it as my universal reference supply for 30-35VDC rails. Having it in a separate box allows me to use a high capacitance mains wire which should remove HF parasitics from the delivered power line and get me a respectable S/N ratio. I don't want to use additional transformers in it. As far as the rectification scheme goes, dual half or full wave and what kind of diodes for either? How do you feel about regulation after the diodes? What are the best tests to describe my transformer and in what order should I perform them. My equipment may not be up to the task, no distortion analyzer but I do have a 35MHz/2mV scope and 6.5 digit meters.
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    Posted 28th August 2014 at 11:53 AM by yldouright yldouright is offline
  17. Old Comment
    fas42's Avatar

    2,000W into 1 ohm

    Good on you! As is obvious from the lack of further input from me here I managed to get sidetracked from pursuing this - this is an endemic problem for me these days - but I encourage you to go for it!

    As regards the best way to produce the rails, in part I would want to know the type of amplifier circuitry it was driving - if a typical circuit I would separate the rails feeding the output stage from all the prior circuitry all the way back to having separate rectifiers for each part. If I wanted to go all the way, I would go an extra step and use a separate, optimal and obviously quite small transformer just to generate the rails for the pre-output circuitry.

    Also, I would like to determine the parasitics of the transformer fairly well, there are methods outlined for determining these; these parameters would be very useful to know.
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    Posted 28th August 2014 at 11:15 AM by fas42 fas42 is offline
  18. Old Comment

    2,000W into 1 ohm

    Okay, this blog has inspired me to try and build a stand alone linear power supply that can deliver 1000W into 1 ohm for 4 channels. I have a slightly used 5kVA house transformer (frame type +/-24V) that I will rubber mount in an aluminum box with the diodes and 4x35mF caps. Which rectification scheme and diode selection is likely to get me the best supply?
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    Posted 28th August 2014 at 06:54 AM by yldouright yldouright is offline
  19. Old Comment
    abraxalito's Avatar

    I found some more suitable EDLCs

    Yes I've noticed a change in my modus operandii when the kit sound's 'there'. No longer do I switch music to see how each piece is 'sounding' now, rather I choose music for itself, for the enjoyment of the performance. So its a good sign if fewer of the 'test pieces' get played and I get all adventurous with listening to new stuff....
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    Posted 27th August 2014 at 07:26 AM by abraxalito abraxalito is online now
  20. Old Comment
    fas42's Avatar

    I found some more suitable EDLCs

    Heh, heh ... know exactly what you mean, . When the beast is singing you think, "Measure, why do I want to measure??! - I know it's workin' right!"

    Something for when you get off the 'high' ...
    permalink
    Posted 27th August 2014 at 05:40 AM by fas42 fas42 is offline
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