Millett "Starving Student" hybrid amp
Aug 2, 2008 at 3:01 PM Post #826 of 7,277
Just another teaser photo of the first prototype of the pcb based version of the amp. Round two in underway so we're making progress.

101082098.jpg
 
Aug 2, 2008 at 3:28 PM Post #827 of 7,277
I've done about half the internals in mine so far, will link to some pics tomorrow.

But I'm still waiting on the mosfets. I ordered them over 2 weeks ago and they still haven't arrived. I've emailed the supplier and should have a reply on monday, but I'm wondering if anyone here is in Australia and has some extras that they would be willing to sell to me if I don't get my order by very early in the week.

If you're in Sydney I could drop by, or I'll pay postage. This is the only thing stopping me from finishing the amp tomorrow, otherwise I'll just have to be patient I guess.
 
Aug 2, 2008 at 4:54 PM Post #828 of 7,277
Quote:

Originally Posted by joe_seattle /img/forum/go_quote.gif
Sorry if this is redundant. Just curious what tubes folks are using and how the sound signature might vary among the different brands. I ordered some for my build and received both Raytheon and RCA. Are there any in particular to get or to avoid?


I have RCA, Sylvania, and G.E. versions (although the G.E.'s look like RCA's that have been rebranded). Honestly, I can't say I hear a big difference among them. Nothing night and day, that's for sure.

Quote:

Originally Posted by lynxkcg /img/forum/go_quote.gif
I have a few of both but I was planning on using the KZ. I'm so confused on what to bypass with what
frown.gif



I've been running the KZ's unbypassed, and it sounds great to me. I have a pair of Vitamin Q's lying around, so I suppose I could do an experiment and bypass one channel, and then do an a/b test listening to each channel while playing a mono lp and see if there is an advantage to bypassing.
 
Aug 2, 2008 at 4:57 PM Post #829 of 7,277
Quote:

Originally Posted by n_maher /img/forum/go_quote.gif
Just another teaser photo of the first prototype of the pcb based version of the amp. Round two in underway so we're making progress.[/IMG]


Looking good. It's nice and compact that's for sure.

So what are your thoughts on the casework for that style of board?
 
Aug 2, 2008 at 6:37 PM Post #830 of 7,277
How warm are everybody's mosfet heatsinks? I used the standard ones from the BOM, but they are very warm to the touch even after just a few minutes on. Is this pretty normal?
 
Aug 2, 2008 at 6:54 PM Post #831 of 7,277
Quote:

Originally Posted by Chipp /img/forum/go_quote.gif
How warm are everybody's mosfet heatsinks? I used the standard ones from the BOM, but they are very warm to the touch even after just a few minutes on. Is this pretty normal?


I think so.

I ended up getting 2" heatsinks so they would be taller than the tubes, and they don't get that warm. Plus they are mounted on an aluminum case, which dissipates even more heat.
 
Aug 2, 2008 at 7:20 PM Post #832 of 7,277
Quote:

Originally Posted by TimJo /img/forum/go_quote.gif
I think so.

I ended up getting 2" heatsinks so they would be taller than the tubes, and they don't get that warm. Plus they are mounted on an aluminum case, which dissipates even more heat.



Good point - mine are mounted into wood. I may look into grabbing the larger 'sinks just to be on the safe side.
 
Aug 3, 2008 at 6:08 AM Post #833 of 7,277
Quote:

Originally Posted by scompton /img/forum/go_quote.gif
I assume since I have Delco tubes that these were originally used in car radios.


You are quite correct!
20080802wtf0001smallcg0.jpg
 
Aug 3, 2008 at 10:44 AM Post #834 of 7,277
Hey bhjazz, where did you find those black oxidized split aluminum enclosures? I've found the silver one at a few places, but I can't seem to find a distributor for the black oxidized ones. Do you think you could hook me up with a link?
 
Aug 3, 2008 at 11:43 AM Post #835 of 7,277
Quote:

Originally Posted by TimJo /img/forum/go_quote.gif
I think so.

I ended up getting 2" heatsinks so they would be taller than the tubes, and they don't get that warm. Plus they are mounted on an aluminum case, which dissipates even more heat.



Me too - my heatsinks don't get very warm at all. For my second Starving Student build, I've got smaller 1.5" 'sinks, but the datasheet quotes their thermal resistance as 3.9c/W which is the same as the 2" heatsinks I used in my first SS?
 
Aug 3, 2008 at 11:52 AM Post #836 of 7,277
Just built my SS today, but seem to have a problem with the right channel and can't seem to figure out whats wrong. The left channel works, and nothing comes out of the right. Both tubes light up the same. Pic posted below.


Thanks.
 
Aug 3, 2008 at 12:10 PM Post #837 of 7,277
keiths, are those smaller heatsinks commonplace? i am thinking of building mine inside the case so that i can just remove the tubes and not have any parts that can break off while traveling.
 
Aug 3, 2008 at 1:42 PM Post #838 of 7,277
Here's a pic of my build. I don't have the fets yet so haven't powered it up. Hopefully my wiring is all correct. It was looking pretty neat as i put it together, then I added ground and other wires and it quickly became messy
tongue.gif


There are more pics - internals and during the build - here.

SS.JPG
 
Aug 3, 2008 at 1:58 PM Post #839 of 7,277
Quote:

Originally Posted by Pandaman /img/forum/go_quote.gif
Just built my SS today, but seem to have a problem with the right channel and can't seem to figure out whats wrong. The left channel works, and nothing comes out of the right. Both tubes light up the same. Pic posted below.


Thanks.



Could you post a better pic of the headphone jack? I'd swear you have the left wired to one side (the correct side) and the right wired to the switched side. That would explain the outage in only the R channel.
 
Aug 3, 2008 at 2:16 PM Post #840 of 7,277
Quote:

Originally Posted by n_maher /img/forum/go_quote.gif
Could you post a better pic of the headphone jack? I'd swear you have the left wired to one side (the correct side) and the right wired to the switched side. That would explain the outage in only the R channel.


Thanks!
Yeah, I had the right wired on the other side, didn't know that you could only solder to one side.
 

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