I'm done with my J-Mo Mk II headphone amplifier.
Excellent results even with my old and not top-line MB Quart Q-45 headphones!
I use external rectifier, CLRC board with K-Multi with about 2V drop and it is feeding 2 Salas BIBs for each channel. Very clean power!
Excellent results even with my old and not top-line MB Quart Q-45 headphones!
I use external rectifier, CLRC board with K-Multi with about 2V drop and it is feeding 2 Salas BIBs for each channel. Very clean power!
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I like your work... congrats... I am glad to know that I am not the only one getting good results with this combo.
Thank you.
I can't tested it properly since I do not have good headphones, yet.
I used my "last century" MB Quart Q-45 with 100 Ohm impedance....
Also, it is difficult to adjust volume level. It is very quick raise at the beginning (1.5 -2 turns) and almost no change after that.
Perhaps you have it connected backwards (upside down)? Also 1.5-2 turns is impossible as the full throw is only about 330 degrees.
The blue Alps pot pictured in the first photo shouldn't have "clicks" either... Tangent's site shows how to wire it up, pin 3 is input (from panel jack), pin 2 is output (to board), and pin 1 is the shared ground.
If your pot has clicks, it is one of those fake non-Alps Chinese attenuators. All bets are off in that case.
If your pot has clicks, it is one of those fake non-Alps Chinese attenuators. All bets are off in that case.
I reconnected as advised in article (How to Wire Panel Components) and "Viola"... all works as prescribed. Thank you.
Yep, it is "Voila"!!!
My misspelling and I hope French guys will forgive my " Russian interpretation of old French".
"Viola" is Finish spread cheese known to every USSR citizen lived during soviet time at 70s.
In 80s its gone and was a deficit…🙂.
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I'm changing Salas BIB setting for 400mA (originally is set to 300mA). My both MOSFETs are at room temperature and I use almost everything from it. Now, I hope, I'll have a room for spare current. Salas told me that I might have some objective performance increase by dripping output impedance by several mOhms. I'll report my outcome soon.
Did not notice a big increase in performance with more than 300mA, but I did notice a substantial increase in detail using more raw voltage feeding the shunts.
For 15V output of the shunts I suggest feeding them 25v rawDC just to have 10V differential in out.
For 15V output of the shunts I suggest feeding them 25v rawDC just to have 10V differential in out.
I have 22.5V input to BIB and 16V out. Do you use 15V to feed headphone amp (not advised 16V)?
I'm performing two more changes for PSU for my J-Mo MkII amp. I already added 2200uF Panasonic FR cups to KM's input, just in case, and I'm changing toroid to 20V secondary vs. 18V which I used till now. So my new delta on Salas BIB Vin vs. Vout will be 10V. I have 6V now. I'll report soon.
Perhaps you can give us a quick summary of your listening setup, just to help us put your observations in context.
For 16Vout I would aim at 26Vin.
10V will make the mosfet more linear with lower impedance
Here is my setup:
1. I use Antek 20V AS-1220 toroid (100VA 2x20V).
2. Then, I have rectifier. I made PCB with rectifiers and snubers (F06U20S diodes).
3. Then raw DC board with KMs. Please see attached schematics. The only difference between schematic and my setup... I added one more 2200uF C to input for each channel. KMs are clasic once from Keantoken site: The K Multiplier
3. Then, I have Salas BIBs set for 356mA current and 16V out.
4. Then, I have headphone amps. I used Elna RFS Silmic electrolytic caps and PRP 0.5W 1% resistors. Only R7 is Vishay CFP 33R 1% 3W. Also, trimmers are exchanged for 3296 Bourns.
5. Source: NAD M5 CD player.
6. Headphones: MB Quart Q45 (I'll get new pair soon. I'm going for AKG K701).
7. Connector: Neutrik #568-NRJ6HM-1-AU
Remarks on J-Mo Mk II PCB.
It is very nice layout, but it is hard to use boutique or flagship (Nichicon Muse KZ or Elna RFS Silmic) capacitors with 5 mm and 7.5 mm leg-spreads. It would be a nice to add such capability. Soldering is not easy and need to heat pads a bit longer then usual. I think it is related to nice-huge GND plain (but it is heat consumer), but also gold plating might help to create tighter eutectic connections.
Remarks on manual.
I assume that connection of potensiometr/attenuator, headphone jack and GND will be nice addition to the manual.
I like the sound even through my old and cheap headphones. Opened and detailed.... I can hear tiny details of each instrument as well as harmony of instrumental chorus. Very natural piano, which is always hard to replicate correctly. I hope to hear quite dramatic change with AKG K701. I'll report that soon...
Also, my next test with new headphones will be also dedicated to vinyl source. I'll report that in near future.
Question:
How to make connection to the source if I would like to set it constantly in-between CD player and Pre-amp. Also, I need to switch its Pre-amp output when headphone is plugged in?
Excellent kit and vast addition to hi-end audio DIY . I really enjoyed that project.
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