[Jo-Sur]

hi.i finish my build today but i have little problem.the right channel the sound is a bit poor,for example the sound of voices not heard much,i measure everything,i change resistors and transitors i swap tubes but nothing.the only strange is that the pin 5 of tube the left have 19v and right have 11,6v.the other measures have normal difference between and parts and pins.any idea???thnks

 

[lukeanderson]

I took the amp apart and everything looked ok. No bridging or burning. I reflowed some of the solder joints that didn't look as good as others.  It has been operating correctly for the last couple of hours. I hope that fixed it and the problem does not come back. Thanks for the help.

 

[tomb]

I took the amp apart and everything looked ok. No bridging or burning. I reflowed some of the solder joints that didn't look as good as others.  It has been operating correctly for the last couple of hours. I hope that fixed it and the problem does not come back. Thanks for the help.

Sounds like you fixed it - congrats!

 

[miig]

Hi Tomb,
 
Thanks for the kind words about my tiny SSMH.
 
Despite mine is an original build, your construction guides & BOM lists at diyforums.org were very usefull.
It's a great reference for those building the kit : http://www.diyforums.org/SSMH/SSMHconstruct6.php
The folded metal heatskins are looking OK and are barely hot in use.
 
The case is a new Hammond reference in anodized blue, I can say the colour actually looks better in true daylight.
 
I got it in my mouser order, plently of version available :
http://www.mouser.fr/Enclosures/Enclosures-Boxes-Cases/_/N-5g3p?P=1z0z2q1Z1z0z2km&Keyword=hammond&FS=True
 
My ref is 1455K1601BU, quite tiny, better get a bigger box
 
----------
 
A note about tubes :
 
I started rolling tubes just 2 weeks ago after running the same pair for six months.
I've no experience in this field but I feel some obvious differences with each tube swap.
 
- RCA 5963 : my first ones (pictured in photo), sound is dark & deep, very coloured
- HP 12au7a : this pair sounds very thin, not my taste
- HP 12au7 (Amperex, 1966 Heerlen factory) : my prefered so far, sound is detailed & punchy, very natural
 
Regards,
 
Miig.

 

[tomb]

Great!
 
I understand Hammond has red anodizing now, too.  They sent me a sample the other day.  It looks very cool.

 

[noemaillard]

Hi all,
 
i just built the starving student kit from beezar, and i am having trouble getting it to work.
sound comes out of the headphones, but there is a very loud crackling.
i checked the voltages and there appears to be only 9.6V where the schematics says it should be approximately 19V (pin 3 of the tubes and pin 3 of the mosfets)
 
 
Any help or advice would be really appreciated

 

[tomb]

  Hi all,
 
i just built the starving student kit from beezar, and i am having trouble getting it to work.
sound comes out of the headphones, but there is a very loud crackling.
i checked the voltages and there appears to be only 9.6V where the schematics says it should be approximately 19V (pin 3 of the tubes and pin 3 of the mosfets)
 
 
Any help or advice would be really appreciated

We need pics ...
 
Please understand that there is no basis with which we can even start to guess what's wrong until we can confirm the basics of your build.
 
I hate to suggest this, but with another customer having trouble with his, I am suspecting the worst when it comes to the resistors.  Once upon a time when selling the MiniMAX, I discovered that a couple of builders had no idea that the resistors all had different values and installed them willy-nilly in the PCB.  After that, I started writing the resistor designations and all of their values on every package.
 
Well, I do not have the time to do that anymore in the case of the SSMH.  So, if there's a chance this is happening, I'm sorry.
 
Here are some basic questions to answer that I shared with the other builder:
 
Do us a favor and measure each resistor (measure ohms with power OFF) with your DMM and fill in this table for us.  Do not go by memory or the SSMH website.  If the resistor designation in the table does not agree with the label on the PCB, do not fill in the measurement for that space – find the right one and measure it, instead:
 

SSMH Resistor Check
Resistor	Ohms	Resistor	Ohms
Right	BOM	Measured	Left	BOM	Measured
R1	33K		R7	33K
R2	220K		R8	220K
R3	2K		R9	2K
R4	220K		R10	220K
R5	2K		R11	1K
R6	2K		R12	2K
R14	1K		R15	1K
R16	100K		R17	100K
R13	2K		NA	NA	NA
* Depends on what you installed

Also – just to check the easy stuff:

• Confirm for us that you have the center post wire of the power jack screwed into the “B+” position on the 4-terminal block.  The outer post wire should go to “G.”
• Confirm that the two switch wires (should be crimped to the pink connectors and pushed onto the switch terminals) are connected to the two “Switch” terminals.  Ensure that none of these wires are touching the other.
• Confirm for us that the large wide vertical stripe on the capacitors C3, C5, and C6 are facing the front of the PCB (toward the volume pot and headphone jack).  C1's stripe should face toward C6.
• Confirm for us that the 220uf 16V writing on the green ES caps face forward at the headphone jack for C8 and away from the 3-position terminal block for C7.
• The tube sockets are on the bottom of the PCB, along with the RLED, right?  Everything else is soldered to the top, right?  I’m sorry for asking that, because I’m not sure you can even assemble the amp if you haven’t done this, but without pics, we're going to have trouble figuring out how to confirm even the basics.

 
Please reply specifically to each question in turn, unless you post pics that can answer some of these.
 
Oh - assuming these are all confirmed, the most common error beyond that is if you have your MOSFETs shorted to the case.  Did you install the shoulder washers?  Were you careful not to torque down the mounting so much that it cut through the insulating pads?  Can you measure zero resistance between the mounting screw/nut and the MOSFET tab (silver metal thing)?
 
Thanks!
 
EDIT: Forgot R10 at 220K.
EDIT2: Revised the entire chart - had it messed up.

 

[tomb]

Another quick question that I should always ask first (maybe I didn't cause I'm in the middle of helping someone else with this) - is the issue in one channel or the other?  If you swap the tubes, what happens?

 

[slimzim]

Hello, I'm a new member of the Head-Fi community. I've been reading this thread for quite some time now since I'm going to build myself a Starving Student amp.
I have bought everything I need, so now I wait for it all to arrive! 

 
I have read around 170 pages already but one thing I can't manage to find is information about cable dimensions inside of the amp. For example, I''ll need to have a short cable between my DC-socket and the powerswitch, since they'll appear on different sides of the chassi. I really don't want to have voltage drops or such.
Would AWG 24 cables be thick enough?
 
Hope I made myself clear, thanks in advance!
Great thread btw!

 

[tomb]

  Hello, I'm a new member of the Head-Fi community. I've been reading this thread for quite some time now since I'm going to build myself a Starving Student amp.
I have bought everything I need, so now I wait for it all to arrive! 

 
I have read around 170 pages already but one thing I can't manage to find is information about cable dimensions inside of the amp. For example, I''ll need to have a short cable between my DC-socket and the powerswitch, since they'll appear on different sides of the chassi. I really don't want to have voltage drops or such.
Would AWG 24 cables be thick enough?
 
Hope I made myself clear, thanks in advance!
Great thread btw!

24ga is OK, but I use 22ga (stranded) exclusively for all hookup wire.  It's about as big as you can go and still fit into most holes.

 

[slimzim]

Okey, then I think I'm ready to go. Thanks a lot Tomb!

Hope my stuff shows up tomorrow, itching in my fingers!

 

[chuckworkb]

Hello all,
 
I just built one of these kits from Beezar and I have one issue. The left channel comes on slightly before and is louder than the right. I tried switching the tubes to see if it changed, and it didn't. I checked all my solder connections and they  look fine.  Do you have any ideas on where to look further for the issue?  I wondered if it could be the pot? I sounds real nice, just unbalanced.
 
Thanks in advance of any ideas you might have for me to check.

 

[tomb]

  Hello all,
 
I just built one of these kits from Beezar and I have one issue. The left channel comes on slightly before and is louder than the right. I tried switching the tubes to see if it changed, and it didn't. I checked all my solder connections and they  look fine.  Do you have any ideas on where to look further for the issue?  I wondered if it could be the pot? I sounds real nice, just unbalanced.
 
Thanks in advance of any ideas you might have for me to check.

 
The Alpha pot is not the best balanced pot in the world, especially at low volume - but it's low cost, as in "Starving Student."

  That's the reason extra resistors are supplied in the kit for the input resistance.  The idea is to "push" the listening range volume into the middle-range adjustment of the pot 's travel.  The Alpha is adequately channel balanced in that range.  You should install the appropriate resistors for your source/headphones if this is irritating you.
 
If you've installed the 100K resistors at the input and this is not enough, try removing one leg of each and soldering the 50K resistors in series with the 100K (for a total of 150K at the input to each channel).  You'll form a resistor "peak" with the joint between the two resistors angled up above the PCB - if you can visualize that.  In other words, two resistors soldered one after the other, bent in the middle so that the combination still fits between the two pads on the PCB.  If you've installed the 50K resistors instead, then take them out and try the 100K's.

 

[chuckworkb]

OK, thanks I will try that.
 
Or, maybe I'll see if I can get a different pot at some point down the road.

 

[slimzim]

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:
Thanks in advance!