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Pars

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  5. and now for something completely different part 3

    in Do It Yourself

    Posted · Edited by Pars

    Documentation? heh

    Which amp? This is a confusing thread because there are at least 3 amps discussed here, maybe more (Kevin or others, correct me if I am wrong):

    1. CFA2 (CFP) - current feedback amp. Each board does 1 channel SE, so 2 for stereo SE, 4 for stereo balanced. Kevin later did a mod to this adding current mirrors feeding the servo. People who had built the original noticed that the servo was audible as to quality of opamp. The schematic in Kevin's archive is the older version.
    2. CFA3 - current feedback amp for balanced. Not sure if anyone ran boards for this one. Basically a pair of CFA2 amps and ubal-bal board on one pcb. Schematic does not show the current mirror mod as in 1 above
    3. uberamp - seems to be a power amp; I've never quite figured this one out :)

    Here are the schematics for the CFA2 (current mirror version), and the CFA3. I also attached my BOM for a CFA2. Amp quantity shown is for stereo SE. If going balanced, double it. It should reflect the later current mirror version. You'll also need some GRLVs or other power supplies, etc.

    cfa2cmirror.pdf

    cfa3production.PDF

    CFP2_BOM_update2018march.xlsx

    EDIT: I also ran across another schematic on Kevin's site which I hadn't seen before: currentsourceamp2.PDF. This seems very similar to the cfa2cmirror schematic, but is described as a transconductance amp.

    • Like 3
    • Thanks 1

  11. Inexpensive decent earbuds...

    in Headphones

    Posted

    On my commute, I have been using Apple Earbuds, which seem to leak a bit of sound. I am normally riding on a train car designated as "Quiet Car" and have had a couple of people look at me if I'm really cranking something, so I was looking for something that didn't leak as much. I know, JH13 :)

    I ran across the HifiMan HE400s on innerfidelity, which Tyll seemed to like, and can get these for around $50. I also noticed they have an HE400i (iPhone) or HE400a (Android). From what I can tell, these do not have a microphone, but do have the inline volume control thingy? The reviews seem to indicate that the inline controls are cheap and break. I never really use these, but if they did have a mic in them, could be useful. This is for use with an iPhone 7 or 8. Sound-wise, the Apple ear buds are fine, but better of course would be appreciated.

    • Thanks 1

  15. krell ksa5 klone

    in Do It Yourself

    Posted

    10 hours ago, davve31 said:

    I bought my kit from the link below, it is your version?
    But i was wondering, on the board it says 2x 10k ohms resistors and 2x 1k ohm resistors. But i got 4x 10k ohm resistors. 

    https://www.ebay.com/itm/Power-supply-board-for-KG-version-KSA5-headphone-amp-PSU-DIY-kit-and-finished/122365758658?hash=item1c7d914cc2:m:mfcUM96JgKu8Wbo08L6PZFw

     

    I guess I get the allure of kits from ebay for the cheap prices, assuming the components are a) genuine, and b) decent quality.

    However, buying a kit and then coming on here without apparently doing a modicum of research first is very bad form. The links to Kevin's board files and schematics/other files are here, but might require a bit of digging. Since that vendor supplies both kits and built units (for a whopping $10 more), one might assume that they build with the same parts as they supply in the kit, and it might not matter whether you use a 1K or 10K resistor in the 2 spots. If you're worried about it, then use some 1K for those two positions.

    But otherwise, the appropriate head-case response is...       :tmonk:

    • Like 1

  23. Tapatalk pro ...blem

    in Suggestions

    Posted

    Getting an error trying to login. Using current password, login etc. I get an error saying that it can't find a user with my email address, and then tells me to log in manually. When I try to do that, it says:

    Server error occurred: '1 Call to undefined method IPS\Login::forms()(MbqRdEtUser.php:29)'

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