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Millett "Starving Student" hybrid amp - Page 453

post #6781 of 6786
Quote:
Originally Posted by Kaaf View Post
 

I have a strange issue

When I'm using my Senn HD600 I don't receive any humm, But when I connect my new NAD viso HP50 I receive an annoying humm in my right ear. Not audiable when playing music but very annoying during silence. It isn't affected by the volumeknob

The HD600 has an impendace of 300ohm and the NAD has a impedance of 25 ohm. Could this cause this rather high pitched hum? And does somebody knows if it's caused by something in particular (already swapped tubes, problem remains right)

definitely the impedance of the headphones not being high enough for the output impedance on the amp... people had the same problem using low impedance cans with Schiit's Vali.

post #6782 of 6786
Quote:
Originally Posted by AHorseNamedJeff View Post

definitely the impedance of the headphones not being high enough for the output impedance on the amp... people had the same problem using low impedance cans with Schiit's Vali.

Quite unlikely. I regularly use my Grado phones (32 ohms) with my SSMH and I remember testing it with my Etymotic ER-6i (16 ohms).

It's probably a grounding/shielding issue which, unfortunately, can be a headache to eliminate.

I can suggest you can start by trying your amp with a different source, different input cables, in a different room, and maybe even a different power supply.
post #6783 of 6786

Hi All,

I've been planning to build a PTP version for quite some time, been reading this (long) post for quite some time. Currently at page 249 (no spoilers please). Unfortunately some of the old posts no longer have linked images working so I may have missed a few things. 

This would be my first point to point so I wanted to make sure I'm following correctly. I drew this diagram from the schematics. 

Does this look correct or am I completely off in my understanding of how to do ptp?

I can't post images so here is a link: http://bayimg.com/aapNCaAFk

 

- The pot is a dual, did not have it in the components of the program I used. 

- Grounds would all go to a star grounding.

- I'd follow indications I found across the thread re. positioning of resistors/caps close to certain components. 

- I'd be using 12AU7 tubes

 

Thanks,

xmx

post #6784 of 6786
Quote:
Originally Posted by ximamp View Post
 

Hi All,

I've been planning to build a PTP version for quite some time, been reading this (long) post for quite some time. Currently at page 249 (no spoilers please). Unfortunately some of the old posts no longer have linked images working so I may have missed a few things. 

This would be my first point to point so I wanted to make sure I'm following correctly. I drew this diagram from the schematics. 

Does this look correct or am I completely off in my understanding of how to do ptp?

I can't post images so here is a link: http://bayimg.com/aapNCaAFk

 

- The pot is a dual, did not have it in the components of the program I used. 

- Grounds would all go to a star grounding.

- I'd follow indications I found across the thread re. positioning of resistors/caps close to certain components. 

- I'd be using 12AU7 tubes

 

Thanks,

xmx

C6 doesn't look right. It should go from the junction of R13, R1, R2, R7 and R8 to ground. In your image it seems it's 'bridging' the junctions of R13-R1-R2 and R7-R8.

 

Aside from that I can't see anything wrong... BUT I just took a quick look and did not confirm the MOSFET pinouts :)

 

cheers!

post #6785 of 6786

wow thanks for spotting that, I had messed out big time. 

 

http://bayimg.com/EapOLAAfK

 

I numbered the MOSFET, 1=G, 2=D, 3=S and made the connections clearer, another thing I need to watch carefully when building. 

 

Thanks again!

post #6786 of 6786

That looks fine. But don't take my word for it! Verify against the schematic (and MOSFET pinout) as you build.  Good luck!

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