Millett "Starving Student" hybrid amp
Apr 17, 2014 at 1:48 AM Post #6,756 of 7,277
Anyone with the 17ew8 build finds the highs a little piercing? I'm using the DT770 pro 250ohm. It's specially noticeable when watching action movies with moderate to high volumes. If I switch to my portable amp (Fiio e6), everything is fine.
 
Is there something I can do to decrease high frequencies on the amp?
I'm thinking my problem could be the combination of the DT770 and the MSSH, because the DT770s are known to have piercing treble and the amp is probably adding even more.
 
Apr 17, 2014 at 11:58 AM Post #6,757 of 7,277
  Anyone with the 17ew8 build finds the highs a little piercing? I'm using the DT770 pro 250ohm. It's specially noticeable when watching action movies with moderate to high volumes. If I switch to my portable amp (Fiio e6), everything is fine.
 
Is there something I can do to decrease high frequencies on the amp?
I'm thinking my problem could be the combination of the DT770 and the MSSH, because the DT770s are known to have piercing treble and the amp is probably adding even more.


No such problem with my 17ew8 & dt1350
 
May 24, 2014 at 5:16 PM Post #6,758 of 7,277
Hey all I just finished my build, original schematic using the 19j6 tubes, and the thing doesn't work. tubes don't light, sound doesn't come through, nothing. any ideas? everything looks hooked up correctly.
 
 
 
also, got a nice 2nd or third degree burn on my arm from my soldering iron whilst building it.
 
May 24, 2014 at 5:26 PM Post #6,759 of 7,277
  Hey all I just finished my build, original schematic using the 19j6 tubes, and the thing doesn't work. tubes don't light, sound doesn't come through, nothing. any ideas? everything looks hooked up correctly.
 
 
 
also, got a nice 2nd or third degree burn on my arm from my soldering iron whilst building it.


Sorry about your arm!  You might try a soldering station that has an iron holder.  That tends to keep the hot iron off the table where you might brush it with your arm.
wink.gif

 
As for the rest - assuming you have two good tubes (it's a bit against probability that both would be bad) - you should be able to light the tubes.  One thing to look for in the Starving Student is that the MOSFET tabs are part of the circuit, so they must be properly insulated from the rest of the amp.  If not, they will be shorted.  Since the tube-heater circuit is connected to and used to bias the MOSFETs, that might be why you don't get the tubes to light.
 
Just a guess ...
 
May 25, 2014 at 10:01 AM Post #6,760 of 7,277
 
Hey all I just finished my build, original schematic using the 19j6 tubes, and the thing doesn't work. tubes don't light, sound doesn't come through, nothing. any ideas? everything looks hooked up correctly.



also, got a nice 2nd or third degree burn on my arm from my soldering iron whilst building it.



Sorry about your arm!  You might try a soldering station that has an iron holder.  That tends to keep the hot iron off the table where you might brush it with your arm. :wink:

As for the rest - assuming you have two good tubes (it's a bit against probability that both would be bad) - you should be able to light the tubes.  One thing to look for in the Starving Student is that the MOSFET tabs are part of the circuit, so they must be properly insulated from the rest of the amp.  If not, they will be shorted.  Since the tube-heater circuit is connected to and used to bias the MOSFETs, that might be why you don't get the tubes to light.

Just a guess ...
alright thanks for your help! I'm gonna post a picture or two for you to look at because I kinda get what you're saying but I could use some more help...
 
May 25, 2014 at 6:13 PM Post #6,761 of 7,277

 

 

 

 
May 25, 2014 at 11:02 PM Post #6,762 of 7,277
I can't get anything from those pics about the MOSFETs.  They're obviously on the other side of the copper plate.  How are they attached?  What are the tabs connected to?  (Must be something.  Otherwise, they'd burn up.)
 
May 26, 2014 at 12:06 AM Post #6,763 of 7,277
I can't get anything from those pics about the MOSFETs.  They're obviously on the other side of the copper plate.  How are they attached?  What are the tabs connected to?  (Must be something.  Otherwise, they'd burn up.)
I used the heater kit that's listed in the BOM sheet and installed it correctly (I think)
 
May 26, 2014 at 8:00 AM Post #6,764 of 7,277
 
I can't get anything from those pics about the MOSFETs.  They're obviously on the other side of the copper plate.  How are they attached?  What are the tabs connected to?  (Must be something.  Otherwise, they'd burn up.)

I used the heater kit that's listed in the BOM sheet and installed it correctly (I think)


The "I think" part is what we're trying to confirm.
wink.gif
  Can you show us a pic of the MOSFETs?  Or, can you measure to see if there's resistance between the MOSFET tabs and the copper plate?
 
May 26, 2014 at 9:38 AM Post #6,765 of 7,277

Here ya go. I'll try measuring right now
 

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