SEX 2.1 completed but not done <SOLVED>

[ditdah]

Hey folks.  Finished my S.E.X. 2.1 this morning.  I'm pretty pleased with it...however, I have a few concerns.

1.  After done...I had 2 resistors left over.  They are the blue kind...120 Ohm  I've looked through the manual twice and can't find where they should be installed.  I'm guessing it's a mistake in shipment.

2.  I noticed that both stock tubes don't glow the same...one, has the filament bridging over the top, while the other does not...which, I'm hoping is the cause of the next bullet.

3.  Resistance checks are pretty good.  Voltage checks yielded 2 flags with me...I get voltage at A1 and it's rising...and I get falling voltage at A2:

Terminal:    Expected:           My Results:
A1, B1        close to 0           4 VDC and rising / 0VDC
A2, B2        375 VDC            360 VDC and falling / 367 VDC

Anyone have any ideas/comments?  I've triple checked all connections.  I'll most likely do so again.  I am sure I have the correct components in all the right areas...I measured each one before installing.  Obviously, if the tube isn't the issue...then I've missed something.  I'll go over it all again in the next day or so.

[ditdah]

shot of my work

[Paul Birkeland]

Hello DD,

The 120 Ohm resistors are an artifact from a prior version of the kit.  From what I can tell, a couple of old packing sheets got used in the last batch of SEX kits, and this extra part was left in.

The differences in the way the tubes glow has to do with the internal construction of the tubes - 1 having the heaters paralleled between sections, the other having them in series.  Luckily, there is no sonic difference between these arrangements (as far as we or anybody else can tell), as the heater is well isolated from the signal.  

Are both A1 and B1 reading 4V?  How high will it rise?  How about the voltages at 9 and 19?  Seeing this problem makes me suspect a miswire with the 249K resistor between 9 and 7 and 19 and 17.

A2 and B2 may be falling from 360V because of the behavior of A1/B1.  

Be sure to let us know what you find.

-PB

[Paul Joppa]

Another possibility is a bad stopper - the 220 ohm resistor connected to A1. Those are the fairly fragile carbon composition resistors and it could be damaged or not well soldered at one end or the other. The resistance check should have caught this - 249K from A1 to ground - but check again while gently poking the resistor and its connections.

It's worth swapping the tubes to make sure it's not simply a bad tube.

[ditdah]

thx for the responses.

A1 and B1 are not reading the same.  A1 was reading 4 volts and growing...I stopped looking once it hit 9. 
B1 is 0.4. 
9 and 19 are below zero. 
I checked the 249K resistors...they are reading correct and installed at the appropriate terminals.

I'll rewet some tonight but I'll try the tube swap first.  I did check the 220 ohm resistor to A1...it reads 230.2...while B1 reads 225.9.

Well, gotta go for now...will get back on it later today/tonight.

[Paul Birkeland]

A1 and B1 are not reading the same.  A1 was reading 4 volts and growing...I stopped looking once it hit 9. 
B1 is 0.4. 
9 and 19 are below zero. 

By below zero, you mean negative voltage?  If so, how much? (under 1V could just be a meter issue)

I too suspect you have a bad carbon comp there, but the good news is that you can substitute one of those extra resistors without any ill effect.

-PB

[ditdah]

below zero was not a good description.  It was above zero...not negative.  The reading was about 0.2 to 0.4 VDC.

ok...I like pointing out my problems when I find them...so others can learn.  Also helps me to reinforce what I've learnt.

There's a jumper from 7 to 12 and another from 17 to 22    ...I found 1 end of each (7 and 17) not soldered.  I blame my eyes!  it took me dawning my magnifying hood with LED lights to find it.  Anyway...soldered up those 2 points.
-Resistance checks as before...just fine.  I find that odd...but whatever...moving on.
-voltage checks...now are OK.  Oddly...slightly lower than they were previously, but still within tollerances and not dropping or rising as before.  So, I seem to have found the problem.  Silly me.   

Live and learn.  Seems the older I get...the more re-learning I'm doing.  Having a blast though.  Love these kits...  I am improving

[Grainger49]

We have all gotten toward the end of a build and forgotten to solder something.  I often suggest letting someone else take a look for you.  You look at it so often that you can't see what is wrong.

Glad you found the unsoldered terminals and can now listen to music.

[Doc B.]

A suggestion to go along with Grainger's excellent one - if you can't recruit someone to look over the amp for you, get away from it for a little while and when you come back do put on those magnifiers. Don't be vein, nobody cares what you look like using a magnifying glass! Rather than going back through the manual to inspect each solder joint in order of assembly, look systematically at both sides of each and every terminal in numerical order. That will help to break up any pattern in your head of the assembly that might cause you to miss a solder joint. Just look for any wire end that doesn't have a nice fillet of solder surrounding it.

[ditdah]

Appreciate the tips.  

Here's a couple more shots...sorry for the quality...best I can do at the moment.

[Grainger49]

Hmmm, Red and Black, University of Georgia colors.

In the first picture I am impressed with the matching curves of the two STP wires coming into the volume control.  Very tidy work.

[ditdah]

Appreciate that.  I wish I had spent time dressing the jumpers for the impedance matching kit.  Actually, they were a little better than now but I had installed the impedance matching kit before I started installing the rectifier (that's my excuse for the left side anyways)...so, when installing, I had to push wires around to get the diode's to where they needed to be.  It was a bit crowded and hard to see...I was nervous about having leads touching things they shouldn't be.  Not as symmetrically dressed as I would have liked...but I think it came out OK.  Otherwise...I'm mostly pleased with the install.

As for the color...it's officially Burgundy as per the Rustoleum can description.  However, it's not as deep as I wanted.  When I do my paramounts and beepre I hope to find a deeper Burgundy color.  I'll spend more time with the wood as well.  Right now, I only stained the exterior...not the interior.  And I haven't sealed it with anything.  I may do more with the next kits.  I keep telling myself the sound is all that matters (and that is 99.99% of what matters to me), but it's nice when you can do a descent job on the aesthetics too. 

Now, if I can only build my next power cord kits without screwing up the techflex.  I'm going to try and create a shield with aluminum foil...and work with the heat gun on a much lower setting.  We'll see how it goes.

Thanks again for the tips folks.  Great community we have here.  I'm pleased to be a part of it.

[Jim R.]

Ken,

Glad you got it all figured out -- do let us know how it sounds when you get it setup.  BTW, I can never find a good burgundy either -- people always describe it to me as Purple, which I am not looking for, but I like a deep, rich, dark red too.

-- Jim

[Grainger49]

   .   .  .     Now, if I can only build my next power cord kits without screwing up the techflex.  I'm going to try and create a shield with aluminum foil...and work with the heat gun on a much lower setting.  We'll see how it goes.

Let me know how that goes.  I really boogered my first one, put metal shield on the second, waiting on the third.

[ditdah]

I don't write audiophile articles...I don't have the "lingo" down.  My source is some lossless stuff on an iBasso DX100, and my cans of choice for now are the Beyerdynamic T1's.  

She sounds great.  I'm pleased that there are no pops or hissing or hums.  She's dead quiet.  The music itself...very nice.  Nice punch to it when it's needed...otherwise, smooth.  I think she's got great depth to the sound.  Very rich.  Not tiring to listen to.  I'm hearing slightly more instrument separation than I heard with my Crack.  It's funny that you can listen to music of a certain artist for years...and then all of a sudden, listen to the same songs again...and hear something you hadn't heard before.  Very cool stuff.  All that make sense?  *I did want to add...somehow, even after what I've said...I love my Crack!  I need some more time to listen some more...but as much as I love this SEX amp, Crack has my heart at the moment.  Especially since I've spent some bucks on new tubes lately.  (maybe just guilt from spending so damn much in tubes...pft)

I don't have tuned ear that some have and I can't give you a good analysis of what I'm hearing compared to the crack or anything else...but I know what sounds good and I'm sold on this kit.  I will add...my primary reason for getting this kit was to drive some new Orca's I have on order.  I'm also going to be playing with some planar magnetic headphones.

P.S.  The tubes are driving me crazy.  I find them pretty damn ugly...am I alone on this one?  The one has a filament bridge (for lack of a better description), while the other doesn't.  I've ordered replacement tubes.  Luckily, these are relatively cheap tubes.  The 300b's I've ordered...not so much.