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lkong

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Posts posted by lkong

  1. and now for something completely different part 3

    in Do It Yourself

    Posted

    1 hour ago, congo5 said:

    I don't know about the 25A draw

    not sure / don't remember

    inrush was above that judging by damage at times

    should have measured it but didn't

    the average magnetic 15A circuit breaker might take 80A to trip instantly

    I sometimes see startup amps on a 3ton A/C go over 110A on 25A fuses and 30A breakers

     

    was using 4 boards

    it was two years ago

    think 5A running on 120v circuit or about 600W at idle from the wall   

    and that's with a low bias of 1A per board 1/4A per pair, 150mv each 0.47R emitter resistor

     

    Yes that 90%  efficienct 800W P/S looks right to me for two boards.

    It depends on your speakers, 8ohms? 4ohoms?

    how much power they and you require.

    How much Bias / class A power you plan on

    if balanced each board only sees half the load so an 8R becomes 4R when calculating Class A or power supply needs

     

     

    Planning to use the amp to drive my Quad ESL 63. Somewhere there might be a pair of Magnepan 3.7 with my name on it, but that's down the road.

  2. and now for something completely different part 3

    in Do It Yourself

    Posted · Edited by lkong

    1 hour ago, congo5 said:

    There are resistors that fit better but I saved a lot of money by getting 100 Xicon's 

    Yes its a very tight fit

      

    That SMPS looks interesting to me and its current limited to 1050W, would add the fan for sure.

    I would like to try it, with two 50v feeding the unreg and with the GRLV set to 40v or slightly lower if using balanced as I don't really need 640 Watts RMS class AB

      

    been wanting to take mine apart and make it into mono blocks that could be used as stereo or balanced and so it wouldn't weigh 80LBS

    also need to double the size of heatsinks or add water cooling

     

    And Yes I had trouble on startup with 1000va of transformer feeding close to 200,000uf of caps

    the current inrush blew  12 35A diode bridges and the resulting short to ground blew up many of my soft start components

    25amp draw that's for 4 boards or 2 boards?

    If it's 25amp for 2 boards, the 800W PS should do 2 boards nicely. If not there's always 2kW ones.

  4. and now for something completely different part 3

    in Do It Yourself

    Posted · Edited by lkong

    16 hours ago, kevin gilmore said:

    There was a cement power resistor tit perfectly, I am not in a position to get the part number now.

     you need the balanced front end board which stacks on top of the amp board if you want to do balanced.

    the +/- reg inputs come from GRLV supplies set for the appropriate voltage (which I don't remember)

    I don't remember what the pot does, probably output current adjust

    single ended its 25 watts pure class A into 8 ohms. Balanced 100 watts pure class A into 8 ohms.

    you can raise the power supply voltages and lower the idle current and get 400 watts into my 8 ohms 50 watts of which are class A

    Obviously you need the appropriate mound of aluminum to get rid of the heat. Or water cooling.

    I think congo5 used xicon, which you will have to bend the legs. That's fine for me.

    1 hour ago, jose said:

    Trimpot is for output current adjust. I used +/- 23Vdc but you can use until +/- 24Vdc.

     If you are thinking of using just one trafo for the four channels you will need a huge trafo. For a balanced configuration I preferred to use two PSU's and two GRLV's

      

      

    I believe the Uberamp drive board runs on +/- 40Vdc. It can certainly run on lower rails.

    It will be a two chassis solution in my case.

    I was inspired by Benchmark AHB2. Is it a good idea to use SMPS for the unreg power supply? Like this one: http://connexelectronic.com/product/smps800re/

    +/- 50 for unreg, and GRLV drops it to +/- 40 for reg.

     

  5. and now for something completely different part 3

    in Do It Yourself

    Posted

    Got my Uberamp boards.

    Here's my version of BOM if it helps anybody: https://docs.google.com/spreadsheets/d/1EIAvFJHqTJL5zzM43FIhz-wJhd_scJiClbLd24QNv9s/edit?usp=sharing

    Here are a few questions:

    1 Power rating of the big .47 resistors. The best option for 10W seems to be this: https://www.mouser.com/ProductDetail/Xicon/280-CR10-047-RC?qs=sGAEpiMZZMtbXrIkmrvidMioh4DscLtBmqbN3KPTLlY%3d Although the lead space is shorter than the length of the resistor. There are a lot more options at 5W.

    2 What's the 5k trim pot for?

    3 How to wire it for balanced setup (2 boards per channel)? Also what are +/- reg drvier for?

  8. Massdrop copycat R2R DAC

    in Home Source Components

    Posted

    5 hours ago, kevin gilmore said:

    years ago I designed a r2r/sacd dac which I would still like to do. But the fpga code was something I knew nothing about, and when I went searching for someone to do the code I ended up with absurd prices in the $350k range. Now given the amount of time that may have been put into this, that was probably not completely out of the range of reasonable. Over the years that price has dropped, a lot recently, someone is willing to sell me the code for $5k. So its clear that the code has been ripped, or reverse engineered and the source code is now readily available.  

    Its also clear from those pictures that the massdrop board is a virtual identical copy of the hibiki board. There is evidently software out there that will take gerber files and turn them back into editable layout files. my guess is that the firmware in the 2 boards is at least marginally different. so they are not the same even though from a hardware standpoint they are completely identical.

    in the end its probably going to be shown that even the stupid high priced spreads (msb,totaldac…) will have a code base that started at the same root.

    another year or 2 and this will all be public domain. Then the math wizzes out there will be able to work on the FIR and IIR code for optimization.

     

    I happened to know sosolar personally. Maybe a collaboration after this wave of MD shit show?

    • Like 1

  15. What Are You Building Today

    in Do It Yourself

    Posted

    2 hours ago, mypasswordis said:

    Story of my life, and probably most DIYers... casework is the worst :( which 3d printer do you have?

    Here is version 1 of the hamster cage, needs a few more improvements before I'm willing to try to machine everything :) 

    bda2c48982.jpg

     

     

    I'm using a Monoprice/Duplicator D6 at home. For bigger and more detailed builds I can use objet and carbon from work.

    Having a 3d printer at home really helps with my procrastination problem. My builds always die during waiting for new parts.

    • Like 1

  17. The Quad thread

    in Speakers

    Posted

    1 hour ago, Craig Sawyers said:

    I used to drive my ESL 57's with an Audio Research D125 hybrid. Solid state front end, and a bunch of 6550 tubes. Sounded great.

    But an old friend (now alas dead) used a Diavelet to drive his much more recent Quad ESL's. But that will be outside your budget.

    Diavelet as their class D amps? People seem to have polarized opinions on class D and ESL. For 1k budget, I can swing a pair of Hypex NC400. But I have no idea if that would be a good fit.

     

  19. The Quad thread

    in Speakers

    Posted · Edited by lkong

    3 hours ago, bjarnetv said:

    I would stay away from hypex dclp.

    There was a group buy here in Norway, and many lost their magic smoke for no reason.

    Hypex haven't been much help in solving the issues as far as i can understand.

    The software is also quite bad.

     

    I used a 2x4 when integrating dipole woofers with my esl63's and that worked great.

    GR servo subs are supposed to be quite good, and i was tempted to buy some a few years back, but shipping to Norway was too expensive.

    Right now i am using a DIY LAB12 Tapped Horn sub and 4x10HD with my dipoles, and if you have the space it's a pretty good solution.

    Easy to integrate, and very effortless big sound.

     

    I think minidsp 4x10HD will be sufficient if not overkill in this case.

    Unfortunately being broke and living in the bay area I have to choose smaller subs.

     

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