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  1. 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 Yesterday at 11:53 AM by yldouright yldouright is offline
  2. 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 Yesterday at 11:15 AM by fas42 fas42 is offline
  3. 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 Yesterday at 06:54 AM by yldouright yldouright is offline
  4. 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 offline
  5. 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' ...
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    Posted 27th August 2014 at 05:40 AM by fas42 fas42 is offline
  6. Old Comment
    abraxalito's Avatar

    I found some more suitable EDLCs

    No, not yet tried that - too much fun listening to the music right now to get into that. Think I'll do a bit of simulation first to get a handle on what the variations might look like in practice.
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    Posted 27th August 2014 at 05:24 AM by abraxalito abraxalito is offline
  7. Old Comment
    fas42's Avatar

    I found some more suitable EDLCs

    Have you tried scoping or sampling what the voltages are at the power supply interface to the chips, right at the junction of the metal leg with the the plastic of the body, while the circuit is running? Could be tricky to monitor with sufficient precision, both in amplitude and frequency, to see whether there is any voltage glitching there, for any reason - and I agree it is most likely self-generated - but it may be instructive. Of course, the probing itself may upset the operation to some degree - but you should be able to get a handle on this by listening with, and without, the probe.
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    Posted 27th August 2014 at 05:03 AM by fas42 fas42 is offline
  8. Old Comment
    abraxalito's Avatar

    I found some more suitable EDLCs

    Yeah its not about size, (or numbers) but effectiveness and that can't be reduced to a quantity no matter what Lord Kelvin might think.

    Living space is already dominated by power supply Frank, in the sense that bags of caps litter my floor, I can barely shift the chair at my desk without shifting a bag or two around to make space. Still now I won't be acquiring normal type caps as supercaps are so much more, ummm, 'super' at getting the sound I'm addicted to. Its really rather surprising that so far I've not uncovered a single audio application in a poweramp of supercaps. I'm not even sure Gilbert Yeung is using supercaps in his preamp (even though he has 300F+ on his supply).

    Yes cleanliness of the PSU seems to be crucial, and my gut tells me its in the lower frequencies where the supercaps are making the difference. To get to 1mohm impedance at 20Hz we need 8F on the rails. So 350F as here is overkill but its needed to get the ESR not to dominate the impedance.

    I'm open to suggestions towards getting LF noise down on the rails - more efficient would be great. I don't know yet if the noise is self-generated (from the ICs themselves) or from the feeding supply. My working hypothesis is its the former because I tend to agree with you that static noise isn't an issue - normal hiss doesn't seem to interfere with how the sound is perceived. But correlate the noise with the signal and then the brain's decoding processes get interfered with.

    Come to think of it, a few months ago, when I was still using AD605 I came up with a circuit intended to nullify (by cancellation) the varying supply current with signal. I might resurrect that schematic and apply it to the AD815. The idea was simple - use a second chip as a 'working model' amplifier and measure in real-time its supply current and use that measurement to correct for the chip doing the real amplification. I had a series of current mirrors to do the fancy footwork. But first it might be instructive to see what variations of supply current are internal to the chip, once the output's loaded with CCSs.
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    Posted 27th August 2014 at 03:14 AM by abraxalito abraxalito is offline
    Updated 27th August 2014 at 03:54 AM by abraxalito
  9. Old Comment
    fas42's Avatar

    I found some more suitable EDLCs

    It's not the size, it's how you use it, ...

    This is getting a bit ridiculous, Richard, ... you might have to fill up your living space with power supply, at the rate you're going ...

    This is all saying to me that the "cleanness" of the power supply to the chips is absolutely crucial - so, personally, I would try to nail a bit more the noise frequencies on the supply lines that are not allowing the chips to work at their best, and then have a more "efficient" way for ensuring that the chips don't see those nasties in their environment.

    But otherwise, excellent that the sound is still improving, in the ways you describe, ...
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    Posted 27th August 2014 at 01:00 AM by fas42 fas42 is offline
  10. Old Comment
    fas42's Avatar

    Windows volume control settings in dB.

    Thanks for putting that up, makes sense from my subjective impressions ...
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    Posted 24th August 2014 at 01:40 AM by fas42 fas42 is offline
  11. Old Comment

    Simple DSP Crossover implemented using PIC32MX450

    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.
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    Posted 23rd August 2014 at 01:40 AM by mbates14 mbates14 is offline
  12. Old Comment
    fas42's Avatar

    Hexasupercap

    Yes, except I would state it as, a good system, rather than speaker - if a completely unknown piece of music, or style of music is heard for the first time, and makes musical sense then the system is in pretty good shape ...
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    Posted 15th August 2014 at 02:21 AM by fas42 fas42 is offline
  13. Old Comment
    miklos's Avatar

    Hexasupercap

    Fas42.
    Provided at your brain know what you supposed to hear.
    If it's the first time one hear an instrument, or a music piece ,that mechanism has not much to rely on. You have to process information, a good speaker give more information.
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    Posted 14th August 2014 at 04:58 PM by miklos miklos is offline
  14. Old Comment
    fas42's Avatar

    Doing interesting things with electronic keyboards

    We have a typical cordless home phone setup, and this, as usual, is a problem child. For those who are into hifi terminology, , the sound goes from 'organic' to non-organic - lots of nasty additives, pesticides, msg type stuff, - when this is operating, . Usual solution has been to pull the plug on it, and go back to the old-fashioned variety of handset, just a bit inconvenient!

    Since we're talking about GHz signals here it is not trivial to work out a "smart" solution ...
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    Posted 11th August 2014 at 02:54 AM by fas42 fas42 is offline
  15. Old Comment
    fas42's Avatar

    Hexasupercap

    Indeed I do, ... as I've said before, there appears almost no end in sight to how good the sound can get - 'weight', 'authority' are good ways to describe where the path takes you, a "massive" quality to the sound presentation can manifest, where the sound world created comes across as so much larger than where you happen to be at the moment, . Ambitious 'pop' productions can become amazing places, where you almost feel you should get a ticket to enter, .

    Remarkably, this depth of presentation can be conjured up by very ordinary speakers, it doesn't seem possible at times - but that's the beauty of the ear/brain mechanism, making sense of all the cues ...
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    Posted 10th August 2014 at 02:52 AM by fas42 fas42 is offline
    Updated 10th August 2014 at 02:55 AM by fas42
  16. Old Comment
    fas42's Avatar

    Doing interesting things with electronic keyboards

    Running the keyboard at realistic volume levels, say for solo piano, works well - but also highlights the strong need to get the interference issue under tight control. Without going the extra steps - at the moment which is shutting everything electrical down which can be heard to affect the sound - then it produces "OK, but ultimately fatiguing" quality ... the hardest step is ensuring an "effortlessness" to the sound. Otherwise, the mind tires of filtering out the residual "edginess" - you lose interest in listening ...
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    Posted 7th August 2014 at 03:17 AM by fas42 fas42 is offline
  17. Old Comment
    fas42's Avatar

    Doing interesting things with electronic keyboards

    Quick comment about conditioning again - I don't know what the underlying cause is here, whether it is a Yamaha thing, an early '90's DAC issue, or that you have a very complex nest of electronics, digital plus analogue all in an integrated environment - but it's quite severe on this unit. Last night got powered down for a number of hours, about 4 or 5 - and the sound had degenerated right back to toy keyboard quality, the treble was abysmal, cymbals were like a hashy, random noise.

    This terrible treble quality in digital sound used to be quite severe years ago - much better in raw gear these days, but still an issue always needing very precise attention to get the best sound ...
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    Posted 6th August 2014 at 11:37 PM by fas42 fas42 is offline
    Updated 6th August 2014 at 11:40 PM by fas42
  18. Old Comment
    fas42's Avatar

    Doing interesting things with electronic keyboards

    Have I mentioned I hate software? ...

    Took the plunge, got a USB to MIDI adapter, and brought a decent MS Vista laptop into the fray. Of course, Vista doesn't know anything about such devices, , so had to hunt around for a kludge solution; a good one was found - but there was a lot of trial and error, and cursing, backward steps, until all was happy. Which means, the Yamaha was happy to be driven by MIDI, and so far I'm very pleased with how it sounds.

    There are milions of MIDI files out there, but the next glitch is that most are set to drive a General version of MIDI, which the Yamaha is too old to know anything about - wrong sounds come out: clarinet rather than pipe organ! Straight acoustic piano is easiest to guarantee a good fit, and so I've tried classical, boogie piano, jazz - works nicely. The grand piano sound is pretty authentic, does an excellent Satie for example.

    The fact that there is an MIDI link may impinge on SQ, but nothing too obvious so far - I'll do some experiments, checking to fine tune this - and work out an easy way to map all the standardised MIDI files to the Yamaha's configuration.
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    Posted 5th August 2014 at 10:47 AM by fas42 fas42 is offline
  19. Old Comment
    abraxalito's Avatar

    Cheapest 32bit CPU to date...

    I deleted your comment SyncTronX as I couldn't see any relevance to this blog. I kept a copy though so if you can explain what it was about I'll restore it.
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    Posted 3rd August 2014 at 08:37 AM by abraxalito abraxalito is offline
    Updated 3rd August 2014 at 08:42 AM by abraxalito
  20. Old Comment
    fas42's Avatar

    Doing interesting things with electronic keyboards

    Okay, have run enough simple tests to demonstrate that the two issues to be addressed are:

    * Warm-up conditioning, and
    * Interference

    The unit was made well enough so that it achieves acceptable, for me, quality if those items are taken care of - I don't believe in fiddling just for the sake of fiddling, I have no desire to get under the hood and possibly cause problems, by doing things that typically people want to play with - only if I believe a genuine major benefit is possible would I venture further.

    The warm-up I can solve merely by running 24/7; and work out strategies for fastest recovery time after the unit is powered off, for any of the obvious reasons.

    Interference is the key concern, so I'll try simple solutions first, and build up to more complex approaches, depending upon how it progesses ...
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    Posted 2nd August 2014 at 12:17 AM by fas42 fas42 is offline
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