diyAudio - Comments
Go Back   Home > Forums > Blogs

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
  1. Old Comment
    wlowes's Avatar

    2013 Holiday Projects - Ridding the system of resistor problems

    Hi Polaron
    Sorry I missed your comment. In my understanding there is absolutely no difference technically/sonically between the $350 assembled unit from Intact Audio and the AVC pair at $200. The assembled version would be very easy, and provides a second fine tuning control. I took th eless expensive route and wired it myself. Took me an afternoon to assemble and wire. I have never needed a finer step in volume than the basic 3db step provided.
    I expect your setup will be very good, but Dave Slagle will happily comment if your system is appropriate for an AVC.
    permalink
    Posted 16th February 2015 at 06:52 PM by wlowes wlowes is offline
  2. Old Comment
    abraxalito's Avatar

    Supercapacitor b*ll*cks

    Yes I agree it would be a much fairer way to describe the array of supercaps to talk about charge. Or even to talk about energy storage. However it is rather common to flaunt uF in power supplies, meaningless as it is without knowing the working voltage.
    I can't imagine how an amp would be able to use the charge all the way down to 0V so I agree that the caps would only be useful over a relatively small proportion of their working voltage.
    permalink
    Posted 16th February 2015 at 04:00 PM by abraxalito abraxalito is offline
  3. Old Comment

    Supercapacitor b*ll*cks

    Maybe the best way to describe it is to say the supercapacitors store a total of seventeen thousand Coulombs of charge.

    Since 1 ampere = 1 Coulomb per second, when you've got 17,000 Coulombs you can supply ten amperes DC for 1700 seconds. Let us send 5 amps DC to the Left channel and 5 amps DC to the Right channel. A little calculator exercise will show you that 5 amps DC will drive a 4 ohm loudspeaker to 50 watts RMS (and twice that for an 8 ohm speaker).

    The announced LIO amplifier stages are rated for only 25 watts, so these seem quite manageable.

    HOWEVER it would be dangerous/silly to discharge the supercapacitors all the way from 100% to 0%. Instead assume they discharge from 100% to 90% (giving up 1/10th of their total charge). Now they can supply ten amps DC for "only" 170 seconds before recharging commences.
    permalink
    Posted 16th February 2015 at 03:00 PM by Mark Johnson Mark Johnson is offline
  4. Old Comment
    rjm's Avatar

    Gustard H10 Headphone Amplifier

    It's a push-pull output, so class AB in principle though its probably biased such that transition out of class A is extremely rare. The exact circuit is a bit of a mystery to me, with four output devices per channel, four smaller transistors, as well as some LEDs and diodes ... the buffer topology does not immediately jump out at me.

    Can't comment about the op amp bias. What you see in the photos is all I know about this amp. There's an unusual level of sophistication to the design compared the usual ebay stuff. I can't even find the rectifiers, let alone decode the voltage regulation! Its troubling resemblance to the Violectric V200 (reverse engineering or ... ?) is no doubt all part of the reason.
    permalink
    Posted 16th February 2015 at 09:11 AM by rjm rjm is offline
    Updated 16th February 2015 at 09:13 AM by rjm
  5. Old Comment
    abraxalito's Avatar

    Gustard H10 Headphone Amplifier

    Impressive array of caps there - seems to have a loyal following over on Headfi. Is it a pure classA output stage? If so with the opamps I wonder if they remembered to bias them into classA too - if not that could be the reason it falls over with higher crest factors.
    permalink
    Posted 16th February 2015 at 02:58 AM by abraxalito abraxalito is offline
  6. Old Comment
    wlowes's Avatar

    Why I DIY

    I totally relate to your thoughts. When I was yonger, I always wanted a good sound system. But I am thrifty. I had lugged around a consumer grade stereo which got only occasional use. about 10 years ago, I pulled the speakers out of storage and realized they needed refoaming. That is how it all started. Now I can thoroughly enjoy developing a project. When it finally comes to life, it is like a first born. I would not trade it for the most expensive audiophile device available. It is mine, and the fact that it makes great sound is just all the more rewarding.
    permalink
    Posted 14th February 2015 at 05:05 PM by wlowes wlowes is offline
  7. Old Comment
    infinia's Avatar

    Mis-understood ArT

    Rapper Kanye West reprised his infamous stunt at Sunday night's Grammy awards, unexpectedly taking the Staples Center stage as Beck was accepting the Album of the Year award.

    I thought he was gonna sucka punch Beck, I reckon Prince wouldn't of done anything either way.
    permalink
    Posted 9th February 2015 at 07:24 PM by infinia infinia is offline
  8. Old Comment

    Velleman K4040 mods

    I've now got a PCB Layout for Alexcp Mods to the K4040 should anyone wish to use it?. I don't know what the bias current is on the KT77's though.

    Regards,
    Mark Snape.
    United Kingdom.
    permalink
    Posted 8th February 2015 at 12:06 PM by SNAPEFU SNAPEFU is offline
  9. Old Comment
    rjm's Avatar

    MUSES premium audio semiconductors from NJR

    I know eh? It's embarrassing.

    Anyhow, the MUSES8820 "feels" very much like a NE5532. That's the sense I get looking at the datasheets anyway. I'm sure it is improved, but nothing jumps out at me as being radically different. That's probably a good thing - it means you can drop the 8820 into any audio circuit, like the VSPS, with no worries.
    permalink
    Posted 6th February 2015 at 05:42 AM by rjm rjm is offline
  10. Old Comment
    abraxalito's Avatar

    TDA1387 octal DAC looks like a good modding base

    For the minimal modding effort (less than an hour overall so far) this is a substantial bargain of a DAC - having just installed 8 * Rubycon 1000uF/6.3V caps on the pin7s, the 'weight' has improved a lot, much more tonal balance now across the spectrum. Very pleasing to listen to, I'll let it burn in for a few hours....
    permalink
    Posted 5th February 2015 at 08:38 AM by abraxalito abraxalito is offline
  11. Old Comment
    abraxalito's Avatar

    TDA1387 octal DAC looks like a good modding base

    Just got mine, opening the box I notice its very cold ( overnight was just below freezing) and Beethoven's Pastoral Symphony was playing from my QA550. Its rough at the top definitely - the piccolo in the storm scene sounded more like a very piercing penny whistle with no depth localisation, the violins are ragged. But I'll give it some time. Dynamics aren't too bad at all, depth cues are all muddled up, sometimes depth is there, sometimes not.
    permalink
    Posted 5th February 2015 at 05:52 AM by abraxalito abraxalito is offline
  12. Old Comment
    abraxalito's Avatar

    TDA1387 octal DAC looks like a good modding base

    Thanks, I'm going over there right away!
    permalink
    Posted 5th February 2015 at 12:10 AM by abraxalito abraxalito is offline
  13. Old Comment
    permalink
    Posted 4th February 2015 at 09:39 PM by Malefoda Malefoda is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 08:41 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2