Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Millett "Starving Student" hybrid amp
New Posts  All Forums:Forum Nav:

Millett "Starving Student" hybrid amp - Page 462

post #6916 of 6926
Quote:
Originally Posted by slimzim View Post

Hello again. I've been thinking for some time now and looking for answers in this thread, but i can't find what I'm looking for.
My question is if there is any chance that this amp(12au7 build) will fry any low impedance headphones? The only thing I've seen is that you can protect your
headphones during the startup sequence by adding diodes. Is there any good tutorial on how to do this since I didn't really understand how it's done.

rolleyes.gif
Thanks in advance!


Buy a Millett Hybrid MiniMAX.

 

Seriously, I don't often make a statement like that because I sell the MiniMAX.  I also sell the current kit offering of the Starving Student.  However, it's a valid statement.  If you are really concerned and don't trust yourself to wait until the amp is warmed up before plugging in your phones, then you need to build something else that has a true, delay-relay circuit (or transformer output) that will protect headphones under most circumstances.

 

Search this thread.  There have been numerous discussions about relay-delays - both early on in this thread and relatively recently.  As with everything else, it will take more effort and money.  At some point, you enter into diminishing returns about whether it's a better decision to upgrade the Starving Student, or build something else that was designed to include more features at the outset.

 

Seriously, the Starving Student offers fantastic performance at an extremely low cost (Thank you, Pete Millett!).  However, there are certain limited expectations that you should temper as a result of that low cost.

 

EDIT: Sorry - it seems like Groundhog Day for some of these questions and I am perhaps over-reacting a bit.


Edited by tomb - 2/17/15 at 6:38pm
post #6917 of 6926
Quote:
Originally Posted by slimzim View Post

Hello again. I've been thinking for some time now and looking for answers in this thread, but i can't find what I'm looking for.
My question is if there is any chance that this amp(12au7 build) will fry any low impedance headphones? The only thing I've seen is that you can protect your
headphones during the startup sequence by adding diodes. Is there any good tutorial on how to do this since I didn't really understand how it's done.

rolleyes.gif
Thanks in advance!

 

It's simple, and to be done with any tube amp: Only plug the headphones in once the amplifier has warmed up and unplug them before powering it down.

post #6918 of 6926

Is what KimLaroux say. Always do that.

 

Cheers

post #6919 of 6926

Well, not any tube amp ...  a true, transformer-coupled amplifier doesn't have capacitors that are needed to block the DC.  The transformers do that already.  You can leave a pair of headphones plugged in all the time.

post #6920 of 6926

Hello mates.
It is a technical question, about Dsavitsk 12au7 additions highlighted.
If I install a toggle switch (two ways) in the input signal, switching R16 & R17 with values 10K and 50k (using 50k potentiometer)
Does this would work as high and low gain?
Or signal become unstable? :O

 

Thanks on advance.

 

Cheers

 

Toni

post #6921 of 6926
Quote:
Originally Posted by fuens View Post
 

Hello mates.
It is a technical question, about Dsavitsk 12au7 additions highlighted.
If I install a toggle switch (two ways) in the input signal, switching R16 & R17 with values 10K and 50k (using 50k potentiometer)
Does this would work as high and low gain?
Or signal become unstable? :O

 

Thanks on advance.

 

Cheers

 

Toni

 

Should work fine.  The Starving Student that was sold long ago at Whiplash Audio did almost exactly what you describe.  I haven't had personal experience with the 12AU7 version, so maybe the gains are different.  If it was the 19J6, you should be switching 50K and 100K, not 10 and 50.

post #6922 of 6926
Quote:
Originally Posted by fuens View Post

Hello mates.

It is a technical question, about Dsavitsk 12au7 additions highlighted.

If I install a toggle switch (two ways) in the input signal, switching R16 & R17 with values 10K and 50k (using 50k potentiometer)

Does this would work as high and low gain?

Or signal become unstable? :O

Thanks on advance.

Cheers

Toni

I completed my build a week ago, and I used 150k ohm resistors and I also used a 50k ohm stereo pot. I also read that capacitor C7 & C8 increases gain so I did not use them. The gain is more than enough this way. Turning the volume up more than 1/3 makes it way to loud for me.
The point is you may want resistors with higher value than 50k. I hope this is to any help! biggrin.gif
post #6923 of 6926

Great!
I'll test it.
Cheers

 

Toni

post #6924 of 6926
Quote:
Originally Posted by slimzim View Post


I completed my build a week ago, and I used 150k ohm resistors and I also used a 50k ohm stereo pot. I also read that capacitor C7 & C8 increases gain so I did not use them. The gain is more than enough this way. Turning the volume up more than 1/3 makes it way to loud for me.
The point is you may want resistors with higher value than 50k. I hope this is to any help! biggrin.gif

Hello Slimzim

The matter is adjust the gain for high an low impedance headphones.

What kind of headphones do you use?

post #6925 of 6926

Now, I have not on my home my Starving Student. Is in my work. (I'm convalescent of work accident)
With a low impedance 32ohm (I remember) I have a little hum.

post #6926 of 6926
Quote:
Originally Posted by fuens View Post
 

Hello Slimzim

The matter is adjust the gain for high an low impedance headphones.

What kind of headphones do you use?

I'm using 32 Ohms at the moment. Audio Technica M50. I have no hum at all, I used a full alu case tough. I think I'll do a remake on the 12au7 schematic for my build. When it's complete i could PM it to you ;)

New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Millett "Starving Student" hybrid amp