Nice work Prasi. I think this is the first photo I have seen of your actual amps.
Btw, I just finished my JFET source follower amp in stereo. Sounds real nice:
I got the DC offset down to 2mV and stable.
Why have you braided the triplets out of the transformer?
That just increases the emi.
And you have some untwisted wires, again increasing emi.
That just increases the emi.
And you have some untwisted wires, again increasing emi.
Nice work Prasi. I think this is the first photo I have seen of your actual amps.
Btw, I just finished my JFET source follower amp in stereo. Sounds real nice:
I got the DC offset down to 2mV and stable.
Thanks X,
Yes, amp building is rare thing now for me as you already know. But i think you must have already seen my FX-8 (still the best sounding of my builds, including spouse's opinion) when you foraged into APEX 100W ulti amp thread.
Before that there were APEX FX-100 (good bass+70V easy capability), PEECEEBEE, Jason's VSSA, slewmaster, P3A, some more in between, etc. Havent posted all the builds, some tried and scrapped/cannibalized for other builds...
Nice going with the other HA and thanks for posting your progress.
reg
Prasi
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Everything is quiet with this amp as of now. will twist some more, if needed. it was a quick build for testing the buffer and see if I can use this amp+buffer combo for driving my HT sub channel. I am going to replace the PSU caps with something more robust! 10000uFx 2 per rail(currently they are 4700uFx2). xfr is also a measly 24-0-24VAC 250 VA. will be replacing with 400 VA 40-0-40VAC, to give some gut power.
i am not so skilled +fat fingers🙂 clumsy.
But one thing to note here, the wires are quite short be it power or signal wires + everything is well separated AC mains , AC secondary and DC and signal.
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It's hard to find a headphone case that can dissipate 50w of waste heat. Maybe use my CPU heatsinks with a small fan is the best solution to keep it compact.
Nice boards! You are going to be real busy mailing them out.
Basic green colored PCBs are still my favorite. 🙂
Basic green colored PCBs are still my favorite. 🙂
yes, green is synonymous with anything related to electronics since the beginning.
i am already very very busy with my HT build and Paul Carmody's sprite boombox build (ND-90) + furniture work at home. haven't had time to look at anything else.
I will start contacting people soon.
regards
Prasi
i am already very very busy with my HT build and Paul Carmody's sprite boombox build (ND-90) + furniture work at home. haven't had time to look at anything else.
I will start contacting people soon.
regards
Prasi
Can you kindly post the Schematics for each of the PCBs in the same post? I practically forgot what I asked for. Also the info will be useful for others visiting the thread later.
schematics for the PSU http://www.diyaudio.com/forums/pass-labs/298369-jumas-head-amp-11.html#post4881036
sch for Juma HA, one channel.
R5 value if using coupling cap can be 100k as suggested by juma. feed back could be three 330 R or one 1 k resistor. C3 is optional and can be left out entirely as per original sch. for good hygiene builds (read Juma's post in reply to XRK). C5, C4, C7, C6 are also optional.
R5 value if using coupling cap can be 100k as suggested by juma. feed back could be three 330 R or one 1 k resistor. C3 is optional and can be left out entirely as per original sch. for good hygiene builds (read Juma's post in reply to XRK). C5, C4, C7, C6 are also optional.
Attachments
xrk- 1 set (1 PSU+1 Stereo HA)+2 buffer
gannaji- 1 set (1 PSU+1 Stereo HA)
saheb- 1 set (1 PSU+1 Stereo HA)+1 buffer
kram- 1 set (1 PSU+1 Stereo HA)
btesize-1 set (1 PSU+1 Stereo HA)
rumina-1 set (1 PSU+1 Stereo HA)-paid
nicusim-1 set (1 PSU+1 Stereo HA)-paid
potepuh-1 set (1 PSU+1 Stereo HA)-paid
e_fortier-2 PSU +1 Stereo HA+2 buffer
touchdown -1 Stereo HA
albertNL- 1 set (1 PSU+1 Stereo HA)-paid
Malvin - 1 set (1 PSU+1 Stereo HA)
one more member through PM-1set(1 PSU+1 Stereo HA)-PAID +paypal fees, thats very considerate of you
one more member through PM-1set(1 PSU+1 Stereo HA)
Thanks
Prasi
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xrk- 1 set (1 PSU+1 Stereo HA)+2 buffer-paid
gannaji- 1 set (1 PSU+1 Stereo HA)
saheb- 1 set (1 PSU+1 Stereo HA)+1 buffer
kram- 1 set (1 PSU+1 Stereo HA)
btesize-1 set (1 PSU+1 Stereo HA)
rumina-1 set (1 PSU+1 Stereo HA)-paid- shipped
nicusim-1 set (1 PSU+1 Stereo HA)-paid- shipped
potepuh-1 set (1 PSU+1 Stereo HA)-paid- shipped
e_fortier-2 PSU +1 Stereo HA+2 buffer
touchdown -1 Stereo HA
albertNL- 1 set (1 PSU+1 Stereo HA)-paid- shipped
Malvin - 1 set (1 PSU+1 Stereo HA)-paid- shipped
one more member through PM-1set(1 PSU+1 Stereo HA)-PAID -shipped
one more member through PM-1set(1 PSU+1 Stereo HA)
Thanks
Prasi
xrk- 1 set (1 PSU+1 Stereo HA)+2 buffer-paid-shipped
gannaji- 1 set (1 PSU+1 Stereo HA)
saheb- 1 set (1 PSU+1 Stereo HA+2 buffer)
kram- 1 set (1 PSU+1 Stereo HA)-paid
btesize-1 set (1 PSU+1 Stereo HA)
rumina-1 set (1 PSU+1 Stereo HA)-paid- shipped
nicusim-1 set (1 PSU+1 Stereo HA)-paid- shipped
potepuh-1 set (1 PSU+1 Stereo HA)-paid- shipped
e_fortier-2 PSU +1 Stereo HA+2 buffer-paid-shipped
touchdown -1 Stereo HA-paid-shipped
albertNL- 1 set (1 PSU+1 Stereo HA)-paid- shipped
Malvin - 1 set (1 PSU+1 Stereo HA)-paid-shipped
one more member through PM-1set(1 PSU+1 Stereo HA)-PAID -shipped
one more member through PM-1set(1 PSU+1 Stereo HA)
one more member through PM-1set(1 PSU+1 Stereo HA+2buffer)-PAID-shipped
Thanks
Prasi
gannaji- 1 set (1 PSU+1 Stereo HA)
saheb- 1 set (1 PSU+1 Stereo HA+2 buffer)
kram- 1 set (1 PSU+1 Stereo HA)-paid
btesize-1 set (1 PSU+1 Stereo HA)
rumina-1 set (1 PSU+1 Stereo HA)-paid- shipped
nicusim-1 set (1 PSU+1 Stereo HA)-paid- shipped
potepuh-1 set (1 PSU+1 Stereo HA)-paid- shipped
e_fortier-2 PSU +1 Stereo HA+2 buffer-paid-shipped
touchdown -1 Stereo HA-paid-shipped
albertNL- 1 set (1 PSU+1 Stereo HA)-paid- shipped
Malvin - 1 set (1 PSU+1 Stereo HA)-paid-shipped
one more member through PM-1set(1 PSU+1 Stereo HA)-PAID -shipped
one more member through PM-1set(1 PSU+1 Stereo HA)
one more member through PM-1set(1 PSU+1 Stereo HA+2buffer)-PAID-shipped
Thanks
Prasi
Need some help guys, please !
I've been having an annoying hiss with my HA, not the Juma specifically. Not sure if it's the best place to post this but maybe you guys can help. Here is the problem and my set-up;
- I'm feeding HA directly from the output of my IQAudio Dac+
- The power supply for the DAC is an etremly low noise IC.
- I choose my songs either via my phone (app called MPDroid) or Volumio 1.55 in my PI.
When the Juma HA is ON, everything connected as it should and I press stop through the app or Volumio it's total silence in my headphone. As soon as I press play I can hear a hiss in the background. I have no SS volume on this HA just a software one.
I also have a Starving Student Millett Hybrid (SSMH) HA which has the same problem except that this SSMH has a 20k volume. If I lower the 20k volume on the SSMH but crank the output to about 50% or more via the app or Volumio the hiss goes away...
The SSMH has a 50k resistor followed by a 20K log stereo volume. The gain of this SSMH is 19 (I know it's high)
It's hard to describe, hopefully you were able to follow. Ask me more if needed.
Thanks in advance,
Eric
I've been having an annoying hiss with my HA, not the Juma specifically. Not sure if it's the best place to post this but maybe you guys can help. Here is the problem and my set-up;
- I'm feeding HA directly from the output of my IQAudio Dac+
- The power supply for the DAC is an etremly low noise IC.
- I choose my songs either via my phone (app called MPDroid) or Volumio 1.55 in my PI.
When the Juma HA is ON, everything connected as it should and I press stop through the app or Volumio it's total silence in my headphone. As soon as I press play I can hear a hiss in the background. I have no SS volume on this HA just a software one.
I also have a Starving Student Millett Hybrid (SSMH) HA which has the same problem except that this SSMH has a 20k volume. If I lower the 20k volume on the SSMH but crank the output to about 50% or more via the app or Volumio the hiss goes away...
The SSMH has a 50k resistor followed by a 20K log stereo volume. The gain of this SSMH is 19 (I know it's high)
It's hard to describe, hopefully you were able to follow. Ask me more if needed.
Thanks in advance,
Eric
One suggestion Eric, did you try feeding the HA with some other source, like a CD player? This will clarify which unit is problematic.
reg
Prasi