Starving Student II Headphone Amplifier
This project looks fantastic! Thanks!!!
I'd like to understand a bit more about its specs. Could we know the amount of Gain? And maybe THD vs output? I read people saying its mostly H2 dominant, but is that accurate? What are the changes from the SSI (that has a bit of reviews out there and can serve as a starting point of conversation until this is out in the hands of others).
But the tech data does not always speak about the sound quality. So, to someone that has heard it (6L6 alone at this point? :) ) or that can 'imagine' its sound based on the schematic:
How would this stand up agains something like the WHAMMY for instance (in terms of pure Headphone AMP or even as PRE)? Perhaps another useful comparison would be the KORG HA-KIT HEADPHONE AMP KIT also available at the store?
I know part of the charm is just building stuff and not always having the best sounding equipment, but there is a limit to what wives allow us to put in the house! ;) :D
So I'm intrigued, as someone that has already built and love the WHAMMY, if this would provide either a significant upgrade or at least a significant lateral move to invest the time for this project and move it to the top of the list... or will it be a little less good overall and be more of a nice project to build rather than a 'better' final product.
And then there is the ultra-practical approach: for someone wanting to get a grip of how tubes sound, how would this new project compare with market options like the Schiit Vali, which I almost bought just to get an idea of tube sound.
Any feedback, either technical or leaning to the subjective side with some measure of objectivity would be very much appreciated.
Thanks a lot,
About the specs...
I'll run some measurements this weekend and post them.
This is very similar to the original Starving Student. It still uses a power MOSFET source follower, which is loaded by the tube heater, and a triode voltage amplification stage.
The main difference is that it uses a different tube (19J6's have become unobtainium), and also the addition of an optional CCS plate load. There's a jumper that lets you select the CCS or a resistor. This changes the sound quite a bit - with the resistor, clipping is softer, and 2nd order distortion is higher. Personally I think this best fits efficient headphones (or preamp use). The CCS raises the gain and lowers the distortion, and the amp can put out more voltage before clipping - but clipping onset is more immediate.
I also added a muting relay to get rid of any "thump" that you get when powering on and off.
I can see that there are some specs now at DiyAudio Store for 30 and 150 ohm load. I have ordered a kit and will probably use the amp most as a pre-amp so behavior in an eg. 10k load is also interesting.
Building this weekend!
Received my parts kit yesterday, really quick processing and delivery! Thanks diyAudio Store. Will get started on it today!:D
Thanks for the info. Indeed, there are now interesting specs, and I... as Meeper, was wondering what the 10K figures would look like.
Great seeing folks already getting their kits, please let us know how they turn out!
So Pete, you would suggest to use the Resistor plate load if it suffices, and only go CSS if you need more gain? What about 300ohm Sennheizer HD600? Where would this fall regarding plate?
After more than 50 years of DIY audio, and upon receipt of the invitation email to purchase the SSII kit, I realized that it is most likely now-or-never to dip my aged toe into the 'sea' of tubes. I purchased the full kit!
I'll be using the SSII with my Hifiman HE400S headphones (22 ohm impedance, 98dB sensitivity).
So questions (in ignorance):
1. How long are the tubes expected to last?
2. Will different tube brands sound different?
3. Would there be any benefit to channel matching to have a matched pair of tubes?
4. Will the tube model become 'unobtanium' like the original SSI tube model has become? That is, should one 'stock up' on a favored tube brand?
5. Would there be any benefit to increasing the size power supply input reservoir capacitor? If so, how much?
My package arrived today and it went together quickly. It really sounds great. Used it as a HPA and a pre-amp . Both times it was impressive. Thanks to the store for a great kit.
The install instructions call for R13 and R21 to be 1.4 watts.
Is this correct?
In the photos they look the same as all the 1/4 watt resistors.
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