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  1. AudioCats

    HiFiMan He-560 driver failure types ?

    I bought a pair of "as-is for repair/parts" he560 off ebay to play with. It is the "adorama exclusive" V4 version and seller was adorama so I suppose it was a customer-returned unit. Phones were in pretty good condition, probably used very little before being returned. The symptom was "audio...
  2. AudioCats

    coffee-fi

    quick review, 1zpresso J-max the good: -- has very very fine adjustment steps. Adjustment is done by rotating the top ring, total adjustment is four and half turns. each turn has 9 #'s, (8.8um per #, according to izpresso), and 10 click per # (0.88um per click). -- solid build, very heavy duty...
  3. AudioCats

    coffee-fi

    another low budget grinder review... USB-rechargable portable coffee grinder, fixxed top hopper, stainless body, (no brand, no model #) This grinder was bought off Amazon for around $25. No model #, no brand. I bought it because the grind adjustment is external, by turning a ring in the...
  4. AudioCats

    What kind of solder for terminating cables?

    If there is enough space on the work bench, it is a good idea to add a Hepa filtration box to capture the fume so it doesn't end up lingering in the room. Hepa filters down to about the same level as N95. https://www.honeywellpluggedin.com/honeywell-true-hepa-tabletop-air-purifier
  5. AudioCats

    What kind of solder for terminating cables?

    since you are in that field, what % of the problem you see is caused by lead and what % from the solder fume (and lead just happens to be present at the same time)? flux fume is a very real problem. I suspect the flux fume from RoHs/lead-free solder might be more toxic than the fume from...
  6. AudioCats

    Dark Voice 336SE mod thread (external cap-box etc)

    End result of thsi DV336 #2 (the "switch broken off, for repair" one) front to back: a) volume pot changed to Alps RK27 50K audio taper, wired as "shunt-pot", ( input resistors are in the back at the RCA jacks) b) power switch replaced to a common short lever type. c) signal wiring (from RCA to...
  7. AudioCats

    Any opinions / reviews on Gemtune APPJ PA1502A

    AN Niobium, interesting :) ... Partsconnexion doesn't carry them. I might try to find some one of these days. I do not agree with Kiwame being better than AN tantalum (as series resistor in shunt-pots). Not even close. in the PA1502A, I think the shinkoh is good enough, AN is kind of an...
  8. AudioCats

    Any opinions / reviews on Gemtune APPJ PA1502A

    I think appj people put a lot of thoughts into the design, I don't worry about heat problem in this little amp. It was not super warm when I was running it in full stock condition, though only for about an hour. I did measure power supply component temps before mods. The hottest part was D3...
  9. AudioCats

    Any opinions / reviews on Gemtune APPJ PA1502A

    yeah, the hum I am hearing is likely (mostly) from my capacitor test rig (long wires connecting to header blocks, allowing fast coupling capacitor change without soldering). I haven't tried different cathode bypass caps yet. The voltage at 6v6 cathode measured around 12v, I will try some...
  10. AudioCats

    Woo Audio WA6-SE - modding to use also as pre amp

    I think the WA6 use output transformers, is it possible that WOO utilizes a different tap for the preamp output signal?
  11. (want to buy) Douk/Nobsound little bear P7 tube amp

    looking for a Douk/Nobsound little bear P7, any condition will be ok (and working or non-functional). It needs to be the 110v AC version though, and shipped from within the US (to Colorado). Payment will be via Paypal. Please PM me if you have one for sale.
  12. AudioCats

    Douk Audio P7 amp

    got my P8 put back together, and one thing I think needs to be done to this design is to (somehow) directly pipe the heat from the cathode power resistors to the aluminum case. I bolted TO220 power resistors directly to the aluminum and the top case surface reaches 51C (hot spot 53C). Who knows...
  13. AudioCats

    Comment by 'AudioCats' on listing '(want to buy) non-functional Douk little bear P7'

    bump. will take either 24v DC or 110v AC version.
  14. AudioCats

    6n5p (6AS7/6080) + 6n11 (6DJ8/6922) OTL headphone amp kit

    can anybody do a long-term impression report on this amp? :)
  15. AudioCats

    Dark Voice 336SE mod thread (external cap-box etc)

    Power resistor area -- Since changing the cathode resistor can noticeably change the sound, I will try different power resistors as well. there are four mounting posts in the sub-chassis; about 7mm height. Sub-chassis has 4 square windows, each 10mmx10mm. Distances from sub-chassis to the...
  16. AudioCats

    Dark Voice 336SE mod thread (external cap-box etc)

    Potting the transformer (top portion) -- this is mostly to allow heat transfer from transformer top plate to the box shell ==> trying to reduce the transformer winding temp. Sacrificed a BIC blue highlighter pen in the process: the pen body served as a drill stop; the end cap will plug the...
  17. AudioCats

    Darkvoice 336i & 336SE Tuberolling PartII

    interested. PM sent.
  18. AudioCats

    Darkvoice 336i & 336SE Tuberolling PartII

    I am looking into current production tubes, PCX has: electroHarmonix 6sn7 $21 electroHarmonix 6sn7 gold pin $43 shuGuang "treasure" CV-181-Z (6sn7) $110 sovtek 6sngt $23 Tung-sol (russian?) 6sn7gtb $27 which one is the most detailed?
  19. AudioCats

    Dark Voice 336SE mod thread (external cap-box etc)

    Disclaimer: HIGH VOLTAGE circuitry. Info presented is for entertainment purpose only. Do not try at home. Starting a thread to document my approach of 336SE mod. MassDrop is selling DarkVoice 336SE for $240. initial impressions: (with the stock tubes and a pair of Beyer DT990-600ohm.) --...
  20. AudioCats

    small transportable Stax amplifier Modification thread

    some serial #'s found on the web: D2S-323x, 252a, assume blue PCB D2S-503x, 252s, not sure which board D2S-705(?), 252s, blue (can not tell if serial was 3 or 4 digit) D2S-797x, 252s, green D2S-090xx, 252s, green D2S-103xx, 252s, green
  21. AudioCats

    The Entry Level Stax Thread

    a little review comparing sr-303 (with 404 pads) and L300 phones: SR-303: this pair is well-used, pads were worn-out so I changed them to the 404 leather pads. Supposedly the 303 and 404 have the same drivers, the only difference are the pads and cable (404 has wide ribbon). So this pair is...
  22. AudioCats

    The Stax Thread III

    The 212/252 can be modded to improve quite a bit but still not quite as full-sounding as even a small desktop like a 313 (with the same mods applied). Transportables like the 252 will not provide a lot of juice to run large phones, ok with Lambda types but nothing larger.
  23. AudioCats

    small transportable Stax amplifier Modification thread

    main components in green PCB srm-252s, serial # D2S-103xx, was part of a srs-3100 set. PCB markings: " PB-201 08451-20010 " power supply section: IC31 SG3524 Q31/32: K975 (Id=1.5A) (212 uses K940, Id=0.8A; blue PCB 252 supposedly have K2961, Id=2A) amp section: Q9/10/11/12: A992...
  24. AudioCats

    small transportable Stax amplifier Modification thread

    google images show blue pcb with insulated TO-220 (same transistor arrangement as in 212), and green pcb with non-insulated TO-220 (arranged differently). I suppose the green one is the newest? when did they start using that? blue pcb...
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