diyAudio - Comments
Go Back   Home > Forums > Blogs
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
    abraxalito's Avatar

    Finally - a cheap FLAC player with digital out

    There are plenty of taobao agents to help buyers outside China.
    permalink
    Posted 16th February 2017 at 02:50 PM by abraxalito abraxalito is offline
  2. Old Comment

    Finally - a cheap FLAC player with digital out

    is not available on aliexpress for anyone living in outside china will hard to buying something stuff in taobao
    permalink
    Posted 16th February 2017 at 02:15 PM by oxoxbyx oxoxbyx is offline
  3. Old Comment
    alexcp's Avatar

    First Watt B1 clone

    Marc, apologies again as I am not getting any faster... I am attaching the Eagle project, PDFs with the schematic and the board, and the gerber files.
    permalink
    Posted 11th February 2017 at 03:14 PM by alexcp alexcp is offline
  4. Old Comment
    abraxalito's Avatar

    My latest infatuation - transformers

    No Youtube here, correct its blocked.

    Trafos will have some magnetostriction - meaning mechanical movement of laminations based on the change of flux in the core. Its normal.
    permalink
    Posted 2nd February 2017 at 12:49 AM by abraxalito abraxalito is offline
  5. Old Comment

    My latest infatuation - transformers

    I get sound From the transformers
    Like a 50hz trafo hum only it's whatever is playing through the amp
    Is YouTube blocked there too?
    permalink
    Posted 1st February 2017 at 10:39 AM by nige2000 nige2000 is offline
  6. Old Comment
    rjm's Avatar

    A power amplifier.

    Hi, thanks for the comment.

    Yes, if you want to push more than 1-2 W peak through this, you'll need to upgrade the output transistors. See note above.

    On the second point, it depends on whether you want to define crossover distortion only as the sharp break in the waveform as one transistors "hands off" to the other, or also include the fact that the two haves of the waveform are reproduced to slightly different scale. For the latter, matched transistors might help. For the former, you are correct.
    permalink
    Posted 1st February 2017 at 01:28 AM by rjm rjm is offline
  7. Old Comment
    abraxalito's Avatar

    My latest infatuation - transformers

    Yes, worth trying the edcores in step down.

    Not sure what you mean about playback noise?
    permalink
    Posted 1st February 2017 at 12:40 AM by abraxalito abraxalito is offline
  8. Old Comment

    My latest infatuation - transformers

    still have them edcore trafos 15k:15k with center taps
    is it worth trying? at 15k : 7.5k

    suppose id want inputs of 1 and 2v and output of 1v and 2v?

    sometimes i notice the output trafos unconnected to speakers make some playback noise is that normal?
    permalink
    Posted 1st February 2017 at 12:28 AM by nige2000 nige2000 is offline
  9. Old Comment

    A power amplifier.

    Nice to see someone design amplifiers! But this one is gonna blow up under heavy load, as BD139 and BD140 output transistors coming in TO-139 package are specified with 1A continuous (and sometimes 2A maximum) current, while 15V*1.4/8R is yet over 2A. Also, matching output transistors does not reduce XO distortion -- only raising bias current of output stage or introducing feedback of output signal can. Happy listening and good luck!
    permalink
    Posted 31st January 2017 at 07:54 PM by Grasso789 Grasso789 is offline
  10. Old Comment
    abraxalito's Avatar

    My latest infatuation - transformers

    Input transformer you can make the size of the ones I brought to your place in September - around 25mm core size. PQ2020 may well work fine. If you tell me your input and output peak voltages and lowest full-power frequency I'll design it for you.

    Its a signal transformer so we don't care very much at all about the winding resistance, so we can make it small using very fine wire.
    permalink
    Posted 30th January 2017 at 11:36 PM by abraxalito abraxalito is offline
  11. Old Comment

    My latest infatuation - transformers

    reducing the gain seemed to do the trick
    tried the autoformer method again
    fairly sure i prefer it

    what sort of spec would i need for the input
    is 20va too big of a core?
    permalink
    Posted 30th January 2017 at 11:01 PM by nige2000 nige2000 is offline
  12. Old Comment
    abraxalito's Avatar

    My latest infatuation - transformers

    Good reason to get yourself an input transformer with taps for gain no? Keep the chipamp at 20dB and adjust accordingly.
    permalink
    Posted 30th January 2017 at 02:19 PM by abraxalito abraxalito is offline
  13. Old Comment

    My latest infatuation - transformers

    ha... ! that wasnt worth censoring
    permalink
    Posted 30th January 2017 at 12:01 PM by nige2000 nige2000 is offline
  14. Old Comment

    My latest infatuation - transformers

    looks like i have to set the gain to suit the input voltage then
    pain in the **** for using the amp with different sources or testing on other guys systems
    permalink
    Posted 30th January 2017 at 12:00 PM by nige2000 nige2000 is offline
  15. Old Comment
    abraxalito's Avatar

    My latest infatuation - transformers

    You're right that having X33 gain is just too high, I suggest reducing it to X20. Increase the 680R to 1k2. I read the DS, you can go as low as X10 if you want (20dB). Putting a resistor divider on the input is a greater evil than gain reduction - with lower gain you get better PSRR.

    I haven't tried auto trafo on the output so far no. Auto trafo has advantage when the step down ratio is low - saves copper. But for higher step downs, not much in it.
    I don't know what the guys at the shop mean by going for a bigger core. It means you can use thicker wire, so get lower copper losses, but core losses will go up and they get quite high at the top of the audio band due to eddy current effects. So I prefer to go as small as possible.
    permalink
    Posted 30th January 2017 at 12:22 AM by abraxalito abraxalito is offline
  16. Old Comment

    My latest infatuation - transformers

    encountered an issue
    when using my amp bypassing the input signal volume pot and using the output tvc
    on input signals of more than 1v into the amp chip i get some type of distortion and approaching 2v is a real mess
    im assuming the gain i had set on the lm3875 (22k and 680 r) x 33 is too much for the supply
    just wondering now whats the lesser evil
    reducing the gain (i read x20 is the min for stable lm3875) or a resistor voltage divider on input?
    when reducing the gain also reduces potential step down on tvc

    also was wondering had you tried the stepdown output as an autotransformer

    an initial test showed some promise of better detail, clarity and deeper bass

    the guys at the transformer shop suggest to go with a "bigger core to improve nominal induction"
    think there's any merit in that?
    permalink
    Posted 29th January 2017 at 05:23 PM by nige2000 nige2000 is offline
  17. Old Comment
    rjm's Avatar

    Converting Eagle printed circuit board layout files to Gerber format

    The combination of gerb274x and excellon generates only 8 files, .whl is not created.

    I didn't notice the change from the previous recipe and will edit the main post accordingly.

    I don't know what the .whl file was but I do know it is not needed anymore.
    permalink
    Posted 29th January 2017 at 03:10 AM by rjm rjm is offline
  18. Old Comment

    Current output...

    An old post, but really interesting. Does someone build the fascinating SERT amplifier published on " Current-Drive - The Natural Way of Loudspeaker Operation" site? It seems it could be done using the same inductors of Sit L'Amp...
    Thank you very much HBC for your time!
    permalink
    Posted 28th January 2017 at 02:54 PM by bonzo15011978 bonzo15011978 is offline
  19. Old Comment
    Calvin's Avatar

    Converting Eagle printed circuit board layout files to Gerber format

    I tried the procedure for eagle 7.5 and all gerber files apart from the .whl are generated.
    What´s the .whl file for and how can I generate it?
    permalink
    Posted 24th January 2017 at 11:52 AM by Calvin Calvin is offline
  20. Old Comment

    Wharfedale Dovedale cone rubber repair

    Since learned that Rubber Renue is a version of oil of wintergreen in (apparently) aggressive xylene
    permalink
    Posted 21st January 2017 at 11:46 PM by Roj Roj is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 02:55 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki