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justin

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Posts posted by justin

  6. Background noise from headamp aristaeus

    in Headphone Amplification

    Posted · Edited by justin

    On 2/12/2023 at 2:39 PM, qqiao said:

    Almost found the reason, the dc gnd and ac gnd doesn't have a connection, I put a 62k resistor and 0.1uf cap between them, almost no noise now.

    The pot case connects to dc gnd, I found it's better than ac gnd. Thank you guys.

    depending on how old the amp is, we added a ground loop breaker later, but where did you come up with this 62k value? We use 10 ohms in parallel with the .1uF cap (300VAC mains rated) in parallel with a 35A bridge rectifier

    you can also try grounding one side of the filament supplies, which are AC

    Surprisingly, we get only 10mVrms of "noise" on the output after careful selection of 12AX7/ECC83 tubes, which is going to have the most influence on your hum. Best I found were the JJ ECC83S which shipped with the amp. Old "special quiet tubes" may not be so quiet.

    • Like 3

  12. The Headcase Stax thread

    in Headphones

    Posted · Edited by justin

    I think similar to Megatron output, so still a lot. max output on the market wasn't goal, more about the DHT sound. if there's an electrostatic headphone that needs more power, going from one of those amps to the other won't be enough of a difference. you may have 1dB, 2dB max more headroom

    • Like 1
    • Thanks 1

  13. The Headcase Stax thread

    in Headphones

    Posted

    On 6/3/2022 at 10:55 PM, TammerDown said:

    In terms of power I assume this is a step closer (but not surpassing?) a T2? 
    We talking above or below the 5 figure point?

    It's more power than BHSE, but not by much. There isn't really much point. There are already several competing tube amps that put out less voltage swing than STAX's entry level amps. Pushing the envelope on component specs to achieve another fraction of a dB more output wasn't the goal.

    as for the price, well over 10k. there is absolutely no way this amp wouldn't be. I could exceed that in bill of materials easily. How much is the MSB, 40k? The Sennheiser HE1 w/ headphone is $59k. The Shangri-la Sr w/ amp is $50k. This will be much, much less than either of those and sound better with SR-X9000 or CRBN.

    • Like 9
    • Thanks 1

  14. The Headcase Stax thread

    in Headphones

    Posted · Edited by justin

    On 12/6/2019 at 3:26 AM, Jon L said:

    Anybody have any idea on price? ?

     

    DHTstat.jpg

    I have been getting back at this..working up to a limited run of these as the STAX SR-X9000 and Audeze CRBN have made that need to happen. But the chassis is extraordinarily expensive and difficult to produce, so I am working at ways to fix that. Also need to put it on the scale, thought it was 45lb but feels more like 60lb haha. It's really not that big of a footprint (13.5x18), but it makes the BHSE look like a toy.

    Power consumption is 190-200W depending on tubes, with 90-100W of that being heaters. The bottom of the amp is ice cold and the top is pleasantly toasty. The first 3 stages have recessed slide switches on top to switch 6.3 to 12.6v heaters, so common tube types are:

    1st: 6SN7/12SN7, 12AU7 and many others w/ 8 to 9 pin adapter
    2nd: 6SL7/12SL7, 12AX7 and many others w/ 8 to 9 pin adapter
    3rd: 6N6P, ECC99, 12BH7A, possibly others such as 5687 w/ pin-out adapter
    4th: Emission Labs 20B-V4
    grand-cayman-proto-2022.jpg

    • Like 28
    • Thanks 1

  19. Cheap Raal Direct Drive Amp

    in Do It Yourself

    Posted · Edited by justin

    16 hours ago, themystical said:

    Seems to be working really well!! 
    Any comments/initial reaction on SQ with and without base boost?

    How warm is the heat sink getting?  Could it be much smaller?

    keep in mind the thermal transfer for this package is not great, with a good insulator the IC will be 3C/W hotter than the heatsink. so you do need to keep the heatsink cool. temperature in this case with the RAAL is dependent on music and how loud you're listening. My guess is in most uses the heatsink will not exceed 40C. with no audio it will be room temp.

    so if the heatsink reaches 40C w/ an average of 15W per IC then the IC temp will be around 85C

    There is also the TO-3 package @ $150 ea. and Apex has parts of a similar price

  20. Cheap Raal Direct Drive Amp

    in Do It Yourself

    Posted

    I received a suggestion that the grounds for the L/R output, which in this case is the 4-pin XLR but would also be the negative posts on the speaker terminals, be wired back to each L/R channel board rather to the star ground at the switching PSUs

    open for debate on that

  21. Cheap Raal Direct Drive Amp

    in Do It Yourself

    Posted · Edited by justin

    7 hours ago, n_maher said:

    Sweet!  You up for giving it a shot driving speakers instead of ear speakers?

    can try but it will be limited by voltage swing. 25W/8-ohm and 50W/4-ohm

    as of right now here is where the difficult work actually starts, and the time consuming work. I'd be interested if anyone wanted to finish it up before putting in the $$/cost on their own unit. 

    for future board revisions:

    - make the jumper over the bass boost 3x 0.1" pins so a push-on jumper can be used + have a place to store it and/or add small signal DPDT 24v relay to switch it (add a 2nd value with moar boost?)

    - don't block the heatsinked part mounting screws with the electrolytic caps

    - holes for wires too small to accommodate 16awg, used 20awg instead

    - caddock resistors need to be bent in an L, move them closer to edge of pcb if possible

    - 2nd output hole for wiring another output

    • Like 2
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