Best DIY kit for the money $250ish - Page 2

Quote:

Originally Posted by hello im sean 

i think im leaning more towards tube to be honest,

Bottlehead Crack is a great amp, and within budget.

cMoy? ;) =P jk.

Starving Student?

Just remember not to use the SSMH (starving student) with the gamma1 or gamma2 DAC's, which I doubt you'd do anyways, but who knows!

Quote:

Originally Posted by wdahm519 

Just remember not to use the SSMH (starving student) with the gamma1 or gamma2 DAC's, which I doubt you'd do anyways, but who knows!

Why?

Quote:

Originally Posted by nikongod 

 

Why?

I guess you missed this issue, because this is sort-of old news.  It started with the AlienDAC, progressed to the BantamDAC, and then the Gamma.  The floating ground of the Cisco VoIP switcher power supply used on the SSMH causes an intermittent static charge to form on the RCA jacks.  If you disconnect/connect the RCA jacks at just the right time, the static charge will fry the DAC chip in the designs mentioned above.

It has to do with those particular designs having no protection from spikes because the output is directly connected to the DAC outputs (not sure about Gamma 2, though).  The coupling capacitors are not enough to block the transient spike in voltage presented by the static discharging.

You can test this on a typical Starving Student amp: disconnect the signal inputs while the amp and source are running and you may get a huge hum - until you ground the RCA jacks with your hand or something similar.  If you don't ground them but re-connect, and the source doesn't have a robust output buffer or opamp, the DAC will see the static charge and most likely fry.

 

The standard gamma2 build uses either a OPA2365 or AD8656 output buffer. The gamma1 has capacitor coupled outputs from the DAC. Based on this and your description of the problem I imagine the gamma2 is probably ok.

The Y2 is not immune to being destroyed by the starving student.

Quote:

Originally Posted by MisterX 

The Y2 is not immune to being destroyed by the starving student.

Just out of curiosity, when it happens does it fry the 8741 or the output op amps?

Quote:

Originally Posted by tomb 

I guess you missed this issue, because this is sort-of old news.  It started with the AlienDAC, progressed to the BantamDAC, and then the Gamma.  The floating ground of the Cisco VoIP switcher power supply used on the SSMH causes an intermittent static charge to form on the RCA jacks.  If you disconnect/connect the RCA jacks at just the right time, the static charge will fry the DAC chip in the designs mentioned above.

 

It has to do with those particular designs having no protection from spikes because the output is directly connected to the DAC outputs (not sure about Gamma 2, though).  The coupling capacitors are not enough to block the transient spike in voltage presented by the static discharging.

 

You can test this on a typical Starving Student amp: disconnect the signal inputs while the amp and source are running and you may get a huge hum - until you ground the RCA jacks with your hand or something similar.  If you don't ground them but re-connect, and the source doesn't have a robust output buffer or opamp, the DAC will see the static charge and most likely fry.
 

Thanks for the info, I had no idea!

It sounds like its mostly a problem when the amp is plugged into the source running, not necessarily an incompatibility of the various devices. 

Quote:

Same as the Y1's I've fixed.... all of the ICs get fried.

Quote:

Originally Posted by MisterX 

Quote:

Same as the Y1's I've fixed.... all of the ICs get fried.

 

Thanks for confirming that for the Gamma2.  I wasn't sure, but suspected it might be the case.

Dsavitsk is working on another version of Pete's Starving Student, but it won't be based on the Cisco power supply anymore.  All that said, however, there's never been an instance of a Starving Student frying a commercial sound card, PDP, or the like.  I use mine regularly for watching movies/Netflix on my PC and have never suffered any ill effects.  It's been dropped a couple of times, had the connectors and tubes ripped out by the dog getting caught in the cables, etc., etc. - all while it's on!  A Pug's curly tail is murder on cables hanging off of a desktop or table.  I wouldn't try that on many amps, but the SSMH is pretty tough.