Juma's Head Amp

[potepuh]

xrk- 1 set (1 PSU+1 Stereo HA)+2 buffer-shipped-delivered
gannaji- 1 set (1 PSU+1 Stereo HA)-delivered
saheb- 1 set (1 PSU+1 Stereo HA+2 buffer)-shipped
kram- 1 set (1 PSU+1 Stereo HA)-shipped
rumina-1 set (1 PSU+1 Stereo HA)- shipped-delivered
nicusim-1 set (1 PSU+1 Stereo HA)- shipped-delivered
potepuh-1 set (1 PSU+1 Stereo HA)- shipped-delivered
e_fortier-2 PSU +1 Stereo HA+2 buffer-shipped
touchdown -1 Stereo HA-shipped
albertNL- 1 set (1 PSU+1 Stereo HA) shipped-delivered
Malvin - 1 set (1 PSU+1 Stereo HA)-shipped
DrizztDo-1 set (1PSU+1 Stereo HA)+1 Buffer- shipped-delivered
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
one more member through PM-1set(1 PSU+1 Stereo HA+2buffer)-shipped -delivered
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
thimios -1 set (1 PSU+1Stereo HA)-shipped
nicusim-1 more set (1 PSU+1HA)-shipped
chat72- 1 set (1 PSU+1HA)-shipped

 

[Kram]

xrk- 1 set (1 PSU+1 Stereo HA)+2 buffer-shipped-delivered
gannaji- 1 set (1 PSU+1 Stereo HA)-delivered
saheb- 1 set (1 PSU+1 Stereo HA+2 buffer)-shipped
kram- 1 set (1 PSU+1 Stereo HA)-shipped-delivered
rumina-1 set (1 PSU+1 Stereo HA)- shipped-delivered
nicusim-1 set (1 PSU+1 Stereo HA)- shipped-delivered
potepuh-1 set (1 PSU+1 Stereo HA)- shipped-delivered
e_fortier-2 PSU +1 Stereo HA+2 buffer-shipped
touchdown -1 Stereo HA-shipped
albertNL- 1 set (1 PSU+1 Stereo HA) shipped-delivered
Malvin - 1 set (1 PSU+1 Stereo HA)-shipped
DrizztDo-1 set (1PSU+1 Stereo HA)+1 Buffer- shipped-delivered
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
one more member through PM-1set(1 PSU+1 Stereo HA+2buffer)-shipped -delivered
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
thimios -1 set (1 PSU+1Stereo HA)-shipped
nicusim-1 more set (1 PSU+1HA)-shipped
chat72- 1 set (1 PSU+1HA)-shipped


It took about 5 days to arrive.

Thanks prasi for all the hard work.

 

[e_fortier]

xrk- 1 set (1 PSU+1 Stereo HA)+2 buffer-shipped-delivered
gannaji- 1 set (1 PSU+1 Stereo HA)-delivered
saheb- 1 set (1 PSU+1 Stereo HA+2 buffer)-shipped
kram- 1 set (1 PSU+1 Stereo HA)-shipped-delivered
rumina-1 set (1 PSU+1 Stereo HA)- shipped-delivered
nicusim-1 set (1 PSU+1 Stereo HA)- shipped-delivered
potepuh-1 set (1 PSU+1 Stereo HA)- shipped-delivered
e_fortier-2 PSU +1 Stereo HA+2 buffer-shipped-delivered
touchdown -1 Stereo HA-shipped
albertNL- 1 set (1 PSU+1 Stereo HA) shipped-delivered
Malvin - 1 set (1 PSU+1 Stereo HA)-shipped
DrizztDo-1 set (1PSU+1 Stereo HA)+1 Buffer- shipped-delivered
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
one more member through PM-1set(1 PSU+1 Stereo HA+2buffer)-shipped -delivered
one more member through PM-1set(1 PSU+1 Stereo HA)-shipped
thimios -1 set (1 PSU+1Stereo HA)-shipped
nicusim-1 more set (1 PSU+1HA)-shipped
chat72- 1 set (1 PSU+1HA)-shipped

Amazing work, thanks Prasi and happy New Year !!

 

[xrk971]

Prasi,
I built up the Nazar PSU today. Can you check the orientation of the diodes D9,D11? They both point in same direction. I can't fire it up until you confirm it's good. I did not have any TIP41/42's so using salvaged SA1930 and SC5171. They are only rated 2amp and 20w, but that should be enough for powering maybe 250mA for a head amp.

 

[prasi]

wow! good catch, in fact D10 should be oriented opposite. how did i miss that one?
i wish you had used MSR860 or atleast MUR860/MUR1560's. nice build...
be careful as your cap is only rated for 25V, make sure unloaded xmfr's voltage is not higher than 17V.

 

[prasi]

here is the corrected D10 schematic.

 

[xrk971]

Thanks Prasi. Flipping the D10 works and PSU is making voltage. I needed to change R3 and R6 from 240R to 100R in order for the pot to be able to adjust the proper range of voltages. With no load I measure 6mV ripple from the PSU with my DMM. I wonder if I am doing something wrong but I would have thought a regulated supply like this gets lower noise.

 

[AndrewT]

What's the Vdc at the input to the regulators?
What's the Vdc before the R9?

The 240r should give a range adjustment from 16.8Vdc down to 6.5Vdc
Something is wrong when you could not get up to your 15Vdc.

Max output = [{1k+2kVR} / 240r + 1] * 1.25V = ~16.8Vdc
Min output = [{1k+0VR} / 240r + 1] * 1.25V = ~6.5Vdc

 

[Salas]

Voltage loss across R1 R9 has someting to do with it and drops out? Needs more Vin? Or T1's base current changes the LM317 equation?
By the way why choosing a rail clean up circuit with 2.7 Ohm output impedance for an hp amp? That will modulate the rail voltage along the signal on high mA swings demand from many headphones. Would be a nice choice for a phono preamp maybe.

 

[xrk971]

I have R22/12 at 330R as gong have 300R. Would that do it?

 

[Salas]

I wouldn't think so since that one is part of the noise shunt

 

[xrk971]

Well I am using a 15vac Antek 0115 transformer. It's got about 20.5vdc at rectifier and CRC so should be plenty to make 15v with.

 

[Salas]

After it will be loaded with the hp amp's current draw the R1 and R9 drops should be contained. So measure across the LMs then to make sure they have no less than 2.5V to work with.

 

[AndrewT]

What's the Vdc at the input to the regulators?
What's the Vdc before the R9?..................

I have R22/12 at 330R as gong have 300R. Would that do it?

Well I am using a 15vac Antek 0115 transformer. It's got about 20.5vdc at rectifier and CRC so should be plenty to make 15v with.

Please measure and answer the questions. this is not a test, I am trying to help you. Don't you want help?

 

[prasi]

What's the Vdc at the input to the regulators?
What's the Vdc before the R9?

The 240r should give a range adjustment from 16.8Vdc down to 6.5Vdc
Something is wrong when you could not get up to your 15Vdc.

Max output = [{1k+2kVR} / 240r + 1] * 1.25V = ~16.8Vdc
Min output = [{1k+0VR} / 240r + 1] * 1.25V = ~6.5Vdc

i am having trouble with my psu too.
the input to lm317 is 22.5VDC
before R9 VDC is 20.9VDC.
unloaded transformer VAC is 17.5 VAC
turning the pot doesnt do anything.

 

[e_fortier]

Hi Prasi,

I'll wait before building mine. Have you used the exact value as per the schematics. Hopefully this can be resolved.

Eric

 

[xrk971]

i am having trouble with my psu too.
the input to lm317 is 22.5VDC
before R9 VDC is 20.9VDC.
unloaded transformer VAC is 17.5 VAC
turning the pot doesnt do anything.

My pot works now after changing 240R to 100R. Before it worked butblikited range with low voltage. Haven't had time to measure test points but trafo and rectifier makes 20.5v so should be plenty to regulate.

 

[e_fortier]

Add a load lets say a 500ohm and see if it works better. Have a look here for the resistor values calculation.

S-Audio Systems - PSU for High end audio without electrolytic capacitors

BR,
Eric

 

[AndrewT]

i am having trouble with my psu too.
the input to lm317 is 22.5VDC
before R9 VDC is 20.9VDC.
unloaded transformer VAC is 17.5 VAC
turning the pot doesnt do anything.

20.9Vdc is high, much higher than the max from the regulator.
Is the regulator actually regulating to a fixed voltage?
Or is it passing an AC contaminated DC?
The voltage before R9 should be 1.25V above the base voltage at the shunt regulator.
The output voltage should be 1*Vbe above the base of the shunt regulator.

 

[AndrewT]

Add a load lets say a 500ohm and see if it works better. Have a look here for the resistor values calculation.

S-Audio Systems - PSU for High end audio without electrolytic capacitors

BR,
Eric

The shunt regulator becomes the load. You don't need to add any more unless the shunt reg is not working.