Stereo 1176 support - Mnats/Hairball

[germoju]

I just looked at your photos again.  It looks like your wiring to your power switch isn't shielded.  That could be the problem specially if the second channel is noisier then the first.  Try removing it from the front panel and pulling the wires away from the other wiring.  Then carefully check for noise again.  You may need to shield that wiring and so it dumps noise to the star ground and not into your audio.  I do that for all my builds now.

If you do, then I recommend covering the shield with something like shrink wrap.  Then if the power wires break they don't make contact to the shield, and then to the chassis, and then you.

oh ok ! But how to shield a wire ?

 

[dandeurloo]

I found a bunch of metal braid wire at a local store that I fit over the PSU wires.  (maybe someone here has a part #)  Then I soldered a ground wire to the shield and connected that end to the star ground.  Then slip plastic cover over it to protect yourself from any damage wires in the future.  It takes a little work but its safe and helps with noise. 

I have done this on my LA 3A's, La 2A's and my 1176's.  Anytime I have mains PSU switches running to the front panels. Specially if its in the center between channels. There is never a clean path away from other controls on the second channel and this does help.

Also, it looks like your front panel is bare aluminum so, as long as your front panel has good continuity to the star ground then your pots and switches should be grounded as well. 

Good luck.

 

[germoju]

Ok thanks ! I will try
I find copper scotch on internet... Specialy to reduce magnetic fields...
I'll tell you when it´s done


Édit : http://www.conrad.fr/ce/fr/overview/2301041/Adhsif-de-blindage

Or better ??? => http://www.conrad.fr/ce/fr/product/545613/Gaine-texture-tisse-mtallique-SCOTCH-24-L-x-l-45-m-x-25-mm-3M-80-0120-2401-6

 

[dacapitan]

hey !

for the LEDs I used 3mm with resistors values 390R for R1 and 1k5 for R2 

Is there a minimum current and voltage rating for the LEDs eg. 5v 40mA? ... Or should any 3mm LED be fine

 

[germoju]

hey !

for the LEDs I used 3mm with resistors values 390R for R1 and 1k5 for R2 

Is there a minimum current and voltage rating for the LEDs eg. 5v 40mA? ... Or should any 3mm LED be fine

If your leds are 5v 40mA and you have +30v and -10v
30 - 5 = 25
25 \ 0,04 = 625 ohm -> use 650 ohm

10 - 5 = 5
5 / 0,04 = 125 ohm -> use 150 ohm

Let the others confirm that cause i'm really not sure !!!

 

[dacapitan]

hey !

for the LEDs I used 3mm with resistors values 390R for R1 and 1k5 for R2 

Is there a minimum current and voltage rating for the LEDs eg. 5v 40mA? ... Or should any 3mm LED be fine

If your leds are 5v 40mA and you have +30v and -10v
30 - 5 = 25
25 \ 0,04 = 625 ohm -> use 650 ohm

10 - 5 = 5
5 / 0,04 = 125 ohm -> use 150 ohm

Let the others confirm that cause i'm really not sure !!!

Thanks for your reply, I would be more comfortable going with a definitive answer - but thanks none the less!

Basically, I just want to know what the minimum ratings (voltage & Current) need to be for the 3mm LEDs on MNATS little PSU when using the 390ohm (R1) and 1500ohm (R2) on MNATs BOM

 

[Harpo]

Basically, I just want to know what the minimum ratings (voltage & Current) need to be for the 3mm LEDs on MNATS little PSU when using the 390ohm (R1) and 1500ohm (R2) on MNATs BOM

Look up the parts datasheet for the LED you are going to order.
Depending on colour (not diameter) of this LED, this will have a forward voltage VF in range 1.6V ... 3.6V and a forward current IF of maybe 20mA ... 30mA for your type of LED. This IF is the rating you don't want to exceed (the opposit of your 'minimum current' request) and some datasheets give a recommended IF 'Rec if' of about half this max.IF value.
The current limiting resistor needed to not exceed LED parts limits and to not build a headlight is (Supply voltage in V - LEDs forward voltage in V) / allowed forward current in A.
A red LED might come with a typical 2V VF and 20mA IF. Allow for maybe half this IF. For your 30VDC status display this resistor would be (30V - 2V)/0.01A=2800 ohm. A 2K7 standard parts value would allow for (30V-2V)/2700R=10.4mA. This resistor has to dissipate (30V-2V)*0.0104A=0.29W. Double up this rating, a 0.6W rated resistor will fit the bill.
The R1 and R2 values from MNats BOM might refer to different psu output voltages. The schematic already tells you "select for propper LED current given selected output voltage".

 

[dacapitan]

Basically, I just want to know what the minimum ratings (voltage & Current) need to be for the 3mm LEDs on MNATS little PSU when using the 390ohm (R1) and 1500ohm (R2) on MNATs BOM

Look up the parts datasheet for the LED you are going to order.
Depending on colour (not diameter) of this LED, this will have a forward voltage VF in range 1.6V ... 3.6V and a forward current IF of maybe 20mA ... 30mA for your type of LED. This IF is the rating you don't want to exceed (the opposit of your 'minimum current' request) and some datasheets give a recommended IF 'Rec if' of about half this max.IF value.
The current limiting resistor needed to not exceed LED parts limits and to not build a headlight is (Supply voltage in V - LEDs forward voltage in V) / allowed forward current in A.
A red LED might come with a typical 2V VF and 20mA IF. Allow for maybe half this IF. For your 30VDC status display this resistor would be (30V - 2V)/0.01A=2800 ohm. A 2K7 standard parts value would allow for (30V-2V)/2700R=10.4mA. This resistor has to dissipate (30V-2V)*0.0104A=0.29W. Double up this rating, a 0.6W rated resistor will fit the bill.
The R1 and R2 values from MNats BOM might refer to different psu output voltages. The schematic already tells you "select for propper LED current given selected output voltage".

Thanks, that actually makes sense now, took me some time but I think I got it now.

If im not mistaken

"red LED might come with a typical 2V VF and 20mA IF for 30VDC status display"

Would be (30V - 2V)/0.02A=1400 ohm ??

 

[Harpo]

Basically, I just want to know what the minimum ratings (voltage & Current) need to be for the 3mm LEDs on MNATS little PSU when using the 390ohm (R1) and 1500ohm (R2) on MNATs BOM

Look up the parts datasheet for the LED you are going to order.
Depending on colour (not diameter) of this LED, this will have a forward voltage VF in range 1.6V ... 3.6V and a forward current IF of maybe 20mA ... 30mA for your type of LED. This IF is the rating you don't want to exceed (the opposit of your 'minimum current' request) and some datasheets give a recommended IF 'Rec if' of about half this max.IF value.
The current limiting resistor needed to not exceed LED parts limits and to not build a headlight is (Supply voltage in V - LEDs forward voltage in V) / allowed forward current in A.
A red LED might come with a typical 2V VF and 20mA IF. Allow for maybe half this IF. For your 30VDC status display this resistor would be (30V - 2V)/0.01A=2800 ohm. A 2K7 standard parts value would allow for (30V-2V)/2700R=10.4mA. This resistor has to dissipate (30V-2V)*0.0104A=0.29W. Double up this rating, a 0.6W rated resistor will fit the bill.
The R1 and R2 values from MNats BOM might refer to different psu output voltages. The schematic already tells you "select for propper LED current given selected output voltage".

Thanks, that actually makes sense now, took me some time but I think I got it now.

If im not mistaken

"red LED might come with a typical 2V VF and 20mA IF for 30VDC status display"

Would be (30V - 2V)/0.02A=1400 ohm ??

Theoretically yes for the LEDs max.allowed current. Exceeding this abs.max.parts rating might blow this part. From your quote you left out my "Allow for maybe half this IF".
As initially said, "Look up the parts datasheet for the LED you are going to order".
All parts come with more or less tolerances. The selected type of LED (they are not all the same, varying in wavelength, brightness, viewing angle, ...) might have a typical 2.0V forward voltage, that could vary by +/-some hundred mV. Resistors come with tolerances. Your psu has a trimmer for dialing in the target voltage and initially you might have dialed in too much when powering on the 1st.time. From Murphys law all tolerances will add in a direction where it will cause the greatest harm.

 

[dacapitan]

Basically, I just want to know what the minimum ratings (voltage & Current) need to be for the 3mm LEDs on MNATS little PSU when using the 390ohm (R1) and 1500ohm (R2) on MNATs BOM

Look up the parts datasheet for the LED you are going to order.
Depending on colour (not diameter) of this LED, this will have a forward voltage VF in range 1.6V ... 3.6V and a forward current IF of maybe 20mA ... 30mA for your type of LED. This IF is the rating you don't want to exceed (the opposit of your 'minimum current' request) and some datasheets give a recommended IF 'Rec if' of about half this max.IF value.
The current limiting resistor needed to not exceed LED parts limits and to not build a headlight is (Supply voltage in V - LEDs forward voltage in V) / allowed forward current in A.
A red LED might come with a typical 2V VF and 20mA IF. Allow for maybe half this IF. For your 30VDC status display this resistor would be (30V - 2V)/0.01A=2800 ohm. A 2K7 standard parts value would allow for (30V-2V)/2700R=10.4mA. This resistor has to dissipate (30V-2V)*0.0104A=0.29W. Double up this rating, a 0.6W rated resistor will fit the bill.
The R1 and R2 values from MNats BOM might refer to different psu output voltages. The schematic already tells you "select for propper LED current given selected output voltage".

Thanks, that actually makes sense now, took me some time but I think I got it now.

If im not mistaken

"red LED might come with a typical 2V VF and 20mA IF for 30VDC status display"

Would be (30V - 2V)/0.02A=1400 ohm ??

Theoretically yes for the LEDs max.allowed current. Exceeding this abs.max.parts rating might blow this part. From your quote you left out my "Allow for maybe half this IF".
As initially said, "Look up the parts datasheet for the LED you are going to order".
All parts come with more or less tolerances. The selected type of LED (they are not all the same, varying in wavelength, brightness, viewing angle, ...) might have a typical 2.0V forward voltage, that could vary by +/-some hundred mV. Resistors come with tolerances. Your psu has a trimmer for dialing in the target voltage and initially you might have dialed in too much when powering on the 1st.time. From Murphys law all tolerances will add in a direction where it will cause the greatest harm.

Ahhhh that makes perfect sense! thanks for being so patient with me and taking the time to explain, got it now!! Thanks Harpo and everyone, Im sure this will also serve other n00bs like me in future

So going on all of this :

I have a RED LED : Vf = 5v, If = (max. 17.5mA) (typ. 13mA)
Green LED :  Vf = 5v, If = (max. 17.5mA) (typ. 11.5mA)

(30-5)/0.013 = 1923 (1.96 kOhms 0.5W 1%)
(10-5)/0.0115 =435 (432 Ohms 0.5w 1%)

Correct?

 

[Harpo]

I have a RED LED : Vf = 5v, If = (max. 17.5mA) (typ. 13mA)
Green LED :  Vf = 5v, If = (max. 17.5mA) (typ. 11.5mA)

(30-5)/0.013 = 1923 (1.96 kOhms 0.5W 1%)
(10-5)/0.0115 =435 (432 Ohms 0.5w 1%)

Correct?

I doubt you have selected a standard LED (from your previous posts a standard LED, through hole, diameter 3mm, colour red, avail.in singles). The typical forward voltage of red GaP or GaAsP LEDs is in range 2.0 ...2.5V. Your given voltage and current values seem to reference a LED module with already built in resistor to operate at these ratings. Could you post a link to this part?
A 3mm through hole standard LED in bulk might be something like these or these.
Ps: updating your profile with your location data might make it easier to help you.

 

[dacapitan]

I have a RED LED : Vf = 5v, If = (max. 17.5mA) (typ. 13mA)
Green LED :  Vf = 5v, If = (max. 17.5mA) (typ. 11.5mA)

(30-5)/0.013 = 1923 (1.96 kOhms 0.5W 1%)
(10-5)/0.0115 =435 (432 Ohms 0.5w 1%)

Correct?

I doubt you have selected a standard LED (from your previous posts a standard LED, through hole, diameter 3mm, colour red, avail.in singles). The typical forward voltage of red GaP or GaAsP LEDs is in range 2.0 ...2.5V. Your given voltage and current values seem to reference a LED module with already built in resistor to operate at these ratings. Could you post a link to this part?
A 3mm through hole standard LED in bulk might be something like these or these.
Ps: updating your profile with your location data might make it easier to help you.

Oh okay, yeah when I filtered Lens Color/Style (Green / Red) it was only returning 1 result for This I see illumination colour is what I wanted to be looking at.

Ive got this and this in my cart now

So going on what was said previously

(30-2)/0.01 = 2800 (2k7  0.5W 2%)
(10-2)/0.01 =800 (820 0.5W 2%)

Correct now?

 

[Harpo]

Yepp.

 

[germoju]

HI !
just wanna say : My Dual 1176 is WORKING without Hummmm or bzzzzzzz !!! YEAH !!

The buzzzz was causing by my front panel red LED !!! I unplug it from DC Current and take my Voltage on AC and buzzz 's gone ! Youuuhou !

Thanks a lot everybody who helped me !!!

 

[DaveHilltop]

I'm close to completing my stereo 1176 build (rotary) and I notice I have not connected anything to the ground pad on the MNATS meter board. In the pictures from the MNATS site it looks like something is soldered to that pad but I cant tell what. I have re-read it several times and unless I'm missing it I dont see where it's mentioned. Perhaps it's just common sense that pad would be tied to one of the ground pads on the main circuit board ?  Thanks, Dave

 

[germoju]

I'm close to completing my stereo 1176 build (rotary) and I notice I have not connected anything to the ground pad on the MNATS meter board. In the pictures from the MNATS site it looks like something is soldered to that pad but I cant tell what. I have re-read it several times and unless I'm missing it I dont see where it's mentioned. Perhaps it's just common sense that pad would be tied to one of the ground pads on the main circuit board ?  Thanks, Dave

Hi,

It's for bypass...
I connected Mnats Meter Board 22/GND > to bypass switch > to Mnats Main board 22/GND
So when my switch is on "Bypass" it connects 22 to GND...

hope I helped

 

[germoju]

Hi everybody !
I'm building a second Dual 1176 with Revision A this time...
I buyed new Purusha case witch is 275 mm now ! So more space !!!

Here is a picture... What do you think about transfos positions ?? Toroid in the middle etc...

 

[DaveHilltop]

germoju,
  Looks good ! Thats just about how I placed everything for my rev D.  By the way I finished my build last night and began calibration. Got through the first two steps and everything is looking good so far. I hope to finish up tonight Regards, Dave   

 

[DaveHilltop]

Hi Everyone !
  Finished up my dual 1176 rev D !  Completed calibration last night. Unit sounds great and is dead quiet. Many thanks to Mike at Hairball, Dan at Collective Cases and Mnats. Have a look at some pics !! Regards, Dave

http://imageshack.us/a/img31/6182/oj9.JPG
http://imageshack.us/a/img689/3986/0ouj.jpg
http://imageshack.us/a/img543/8149/ezcs.jpg

 

[germoju]

Hi Everyone !
  Finished up my dual 1176 rev D !  Completed calibration last night. Unit sounds great and is dead quiet. Many thanks to Mike at Hairball, Dan at Collective Cases and Mnats. Have a look at some pics !! Regards, Dave

http://imageshack.us/a/img31/6182/oj9.JPG
http://imageshack.us/a/img689/3986/0ouj.jpg
http://imageshack.us/a/img543/8149/ezcs.jpg

Cool Good pictures !!
It's a Dual Mono... I cant see any stereo link boards.... (??!!)