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  1. Old Comment
    dady's Avatar

    PSE JJ 2A3/40 Convertible 7 to 15W amp

    With 300B also, get 15 or more watt.
    permalink
    Posted Yesterday at 08:14 AM by dady dady is online now
  2. Old Comment
    abraxalito's Avatar

    New active speaker on order from Taobao

    Well that's bad news for learning, big mistakes spawn major lessons
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    Posted Yesterday at 12:43 AM by abraxalito abraxalito is offline
  3. Old Comment
    fas42's Avatar

    New active speaker on order from Taobao

    Seems as if you can't put a foot wrong at the moment, Richard ...
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    Posted 29th September 2014 at 11:27 PM by fas42 fas42 is offline
  4. Old Comment
    abraxalito's Avatar

    Revisiting active speakers - HiVi D1010

    Yep, time and time again it all comes down to power supplies. I created a slogan 'No matter how important you think power supplies are, they eventually turn out to be even more important than that'.

    For example, just this week I've been surprised how good active opamp-based filters can sound, given top-notch power supplies. I'd never have imagined humble old TL084 (price 0.6rmb on Taobao) sounding that good so long as its PSU is looked after carefully. So much so that I'm considering active filters again.

    Having a decent sounding JFET buffer (and costing 0.15rmb) means cap sizes can all be reduced considerably, C0G ceramics get considerably cheaper at lower values.
    permalink
    Posted 24th September 2014 at 02:43 AM by abraxalito abraxalito is offline
    Updated 24th September 2014 at 02:47 AM by abraxalito
  5. Old Comment
    fas42's Avatar

    Revisiting active speakers - HiVi D1010

    Nice continuing saga - note that the major benefits come through from giving the power supply more grunt, in every area - highly likely the hash and tubbiness will be resolved at a certain point, just by focusing on that ...
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    Posted 24th September 2014 at 01:27 AM by fas42 fas42 is offline
  6. 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....
    permalink
    Posted 22nd September 2014 at 05:53 AM by abraxalito abraxalito is offline
  7. 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.
    permalink
    Posted 22nd September 2014 at 05:17 AM by fas42 fas42 is offline
    Updated 22nd September 2014 at 05:20 AM by fas42
  8. 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.....
    permalink
    Posted 22nd September 2014 at 04:16 AM by abraxalito abraxalito is offline
    Updated 22nd September 2014 at 04:19 AM by abraxalito
  9. 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 ...
    permalink
    Posted 22nd September 2014 at 03:19 AM by fas42 fas42 is offline
  10. 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 ...
    permalink
    Posted 22nd September 2014 at 03:02 AM by fas42 fas42 is offline
  11. 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....
    permalink
    Posted 22nd September 2014 at 02:21 AM by abraxalito abraxalito is offline
  12. 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 ...
    permalink
    Posted 22nd September 2014 at 12:33 AM by fas42 fas42 is offline
  13. Old Comment
    fas42's Avatar

    Revisiting active speakers - HiVi D1010

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

    Super Regulator PCB's for free

    Boards are available. Send me a message.
    permalink
    Posted 9th September 2014 at 01:10 PM by peranders peranders is offline
  15. 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.
    permalink
    Posted 6th September 2014 at 01:44 PM by googlyone googlyone is offline
  16. 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
  17. 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
    permalink
    Posted 1st September 2014 at 06:16 PM by anystereo anystereo is offline
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