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Millett "Starving Student" hybrid amp
Apr 17, 2009 at 11:29 PM Post #2,986 of 7,277
Ah, don't wanna do that then
wink.gif
 
Apr 18, 2009 at 12:54 AM Post #2,987 of 7,277
Ok, when I plug in the headphones, the tubes get way less bright. I'm thinking that's why I'm hearing little to no sound. Even with the pot maxed out. I rewired the pot, so that isn't it. Can someone please help me!?!?
 
Apr 18, 2009 at 1:24 AM Post #2,988 of 7,277
Quote:

Originally Posted by Bleuburd /img/forum/go_quote.gif
Ok, when I plug in the headphones, the tubes get way less bright. I'm thinking that's why I'm hearing little to no sound. Even with the pot maxed out. I rewired the pot, so that isn't it. Can someone please help me!?!?


We can't do much without more information - please post some clear pictures and we'll do what we can. You clearly have something wired incorrectly.
 
Apr 18, 2009 at 2:12 AM Post #2,989 of 7,277
Apr 18, 2009 at 12:02 PM Post #2,990 of 7,277
I thought the options schematic was the one most people were building. Let me tell you, it screams! IMHO that is the schematic to go with.
atsmile.gif


I have the resistors in before the pot and I can't have the headphones on past 3/4 of the way. After I built and tested mine for a couple days I put a very simple crossfilter circuit in before the pot (2 caps + 3 resistors). Only made a miniscule drop in gain.

One idea for those who are new at this and plan to build point to point - Sit down with pencil and paper first. Draw out your parts placement then sketch out the wiring. Use different colors if need be to follow input, output, power and ground. Refer to the schematic and see if it makes sense. Reposition components to reduce the wiring as much as possible, within reason of course.

I don't have a camera with a macro to show the detail but I used Cat5 strands for wiring and color coded each channel, power and gound. This could help if you had diagnose a problem after the build ...and it looks good too.
 
Apr 18, 2009 at 1:38 PM Post #2,991 of 7,277
Quote:

Originally Posted by Swingtops /img/forum/go_quote.gif
n_maher

Here are some pics

http://img2.imageshack.us/img2/4138/dscf1889.jpg
http://img2.imageshack.us/img2/2120/dscf1890.jpg
http://img2.imageshack.us/img2/6045/dscf1891.jpg
http://img2.imageshack.us/img2/8100/dscf1892.jpg

I tried to get the best angles I could but most of the resistors are buried


With that much wiring and with many of the joints hidden beneath the perfboard, I'm afraid it's going to be impossible to trouble-shoot. You might look at a few things I saw:

1. If you can reduce the length of all that wire, or at least tie a piece of tape around the leads that you can trace and label it.
2. It appears to me that you have several splices in the wiring that are un-insulated and dangerously close to touching the metal case. Wrap those with electrical tape, or unsolder them, slide on some heat shrink, re-solder, then slide the heat shrink back over the joint and shrink.
3. Likewise, I'm also suspecting that there are un-insulated joints beneath that perfboard. With it slapped up against the case, there may be joints that are touching/shorting out.
4. It's difficult to tell, but it looks like you have the headphone jack wired up wrong. There are three solder lugs, but you've only run wiring to two. Then it looks like you've soldered directly to one of the contacts. Further, you've run double leads to two of them. The most efficient method would've been to join the leads between the R12-C5 joint (Left) together and join the leads between the R6/C3 joint (right) together on the perfboard, and run single leads only for the Left and Right channel, respectively. The way you have it may result in proper wiring anyway, but it certainly leaves yourself open to error.
5. Note that the method mentioned in #4 may help reduce the wiring elsewhere. Extra leads and extra length will promote more noise and hum in the amp.
 
Apr 18, 2009 at 10:21 PM Post #2,992 of 7,277
Ok, it's not the mosfets and it's not the pot. I fixed some wiring that I fouled up, and now I still have the same problem. I can't hear anything. When the pot is turned all the way up, then I can hear something faint, but it isn't at all listenable. Here are pics as requested. Sorry, they aren't very good, and I didn't really know how to get good shots of the inside. By the way, I housed it in a cigar box. Smokey student hybrid?

zu46dc.jpg

21eqj29.jpg

14j50n5.jpg
 
Apr 18, 2009 at 10:28 PM Post #2,993 of 7,277
tomb
Thanks for taking a look at it for me - the case is actually plastic, so I am not too concerned about shorts on the back side of the perf board but the splice I will take care of.
I began looking over the schematic again and I think I have some serious problems ( perhaps wiring at 4:30 am is not recommended ) one of the .1 uF caps is not even hooked to anything.
I also started to put the amp in DIY layout creator and it turned out to be a big CF so I think I might just start over with a new layout that I have thought about for a bit

thanks again
 
Apr 18, 2009 at 10:51 PM Post #2,994 of 7,277
Quote:

Originally Posted by Swingtops /img/forum/go_quote.gif
tomb
Thanks for taking a look at it for me - the case is actually plastic, so I am not too concerned about shorts on the back side of the perf board but the splice I will take care of.
I began looking over the schematic again and I think I have some serious problems ( perhaps wiring at 4:30 am is not recommended ) one of the .1 uF caps is not even hooked to anything.
I also started to put the amp in DIY layout creator and it turned out to be a big CF so I think I might just start over with a new layout that I have thought about for a bit

thanks again


Sorry I wasn't of more help. If your case is plastic, you're right - no problem with the shorting. Still, a fresh start might be best. Remember that a goal is to minimize the wiring as much as possible. That will always work best. Review Pete's original build photo and also Nate's. That's kind of a key to how the wiring should go. You can copy what's in the photos directly - that's the easiest.
 
Apr 18, 2009 at 10:52 PM Post #2,995 of 7,277
Quote:

Originally Posted by Bleuburd /img/forum/go_quote.gif
Ok, it's not the mosfets and it's not the pot. I fixed some wiring that I fouled up, and now I still have the same problem. I can't hear anything. When the pot is turned all the way up, then I can hear something faint, but it isn't at all listenable. Here are pics as requested. Sorry, they aren't very good, and I didn't really know how to get good shots of the inside. By the way, I housed it in a cigar box. Smokey student hybrid?


Can you make your pictures larger?

Start by tracing the signal path from the inputs to the pot to pins 5 and 6 of the tube sockets.
 
Apr 18, 2009 at 11:00 PM Post #2,997 of 7,277
Quote:

Originally Posted by Bleuburd /img/forum/go_quote.gif
Sure, bigger pics in the next hour.


Also, take off the masking tape. There are junctions where it is hard to match the wires going under the tape to the ones coming out.
 
Apr 18, 2009 at 11:06 PM Post #2,999 of 7,277
A similar thing happened to me recently. It was caused by the RCA jacks getting loose because of my lousy case work. Basically the nuts became loose enough that there wasn't a ground. I tightened up the nuts and every thing worked fine.
 
Apr 18, 2009 at 11:12 PM Post #3,000 of 7,277
Edit: Well, I rewired the mosfets and mixed up the drain and the source. The resulting current blew the drivers in my hd580s. I'm done. Sorry guys, this is crazy. I've lost money, the amp never worked, and now I have no reason to finish it. This is really upsetting. The hd580s where my only cans. I guess somebody might want them for $50 to replace the drivers. I'm sticking with my ibasso and some IEMs when I get the cash.

Sincerely,
~Bleuburd
 
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