[tomb]

You need to go over every transistor solder joint in that left channel very carefully.  Looking at QB2L, I can't believe the leads are not touching.  It appears that the transistor is bent sideways so far to the headphone jack side that the far edge of the transistor is over the center pad.  If the leads are bent sideways that far, chances are they're touching.  There's also a solder blob on QB3R that looks big enough to cover both pads.  Make certain you don't have any solder blobs touching other pads and inspect all of the transistor leads to ensure that you don't have anything touching.  Are the pads clean and leads secure on the heat sinked transistors?
 
Can you get us similar pics of the bottom of the PCB?  I'm beginning to think it's some messy solder joint somewhere that's shorting out.  We can't confirm the transistors from these pics, but if you've double-checked that none are in the wrong place and you've already checked and measured the resistors, then that leaves a short somewhere as the issue - touching lead, solder blob out of place, etc.
 
 
EDIT:  Just an FYI, but I'm afraid you're going to have problems casing it up unless you change the mounting of those Vitamin Q's - they appear to be too high toward the center.  You should refer to this detail from the MiniMAX website:

 
This image is a little ideal, but there's a scale PDF link below on that page (http://www.diyforums.org/MiniMAX/MiniMAXvitQ.php) that has it drawn exactly:
http://www.diyforums.org/MiniMAX/vitQ/VitQinstall.pdf
 
The key is that I don't think you can get the height low enough (without shorting out the leads) unless that tall lead is bent slightly back under the VitQ and soldered into one of the interior holes - not the outside one.

 

[QRomo]

The MiniMAX is my first tube amp, so excuse my ignorance, but is there a lot of variation in how microphonic these Millet tubes are? The first set I tried were the 12FM6's that came with my kit and they picked up any vibration transmitted through the chassis. I figured it was just par for the course and it was really only a problem when I tapped the chassis or changed the volume (and only faintly on volume change), so it didn't bother me. However, I recently decided to give a couple 12AE6's a try and once I swapped them in I found them to be dead silent, even when I tap the tubes directly. Did I get a bit lucky with the 12AE6's or a bit unlucky with the 12FM6's?

 

[jdkJake]

Unlucky with the 12FM6's.
 
Most Millett tubes I have are dead silent. I have a couple that are just slightly microphonic, but, they sound so good, I tolerate them nonetheless. If it is highly microphonic, I usually return them. In general, most tubes I have used are fine (and I have a serious Millett tube fetish going on!)
 
Where did you get them? Most places will take them back and/or replace them if they are microphonic. It is something that cannot be tested except by listening.
 
EDIT, just realized you got these from Beezar. Contact Tom, he will take them back and get you a new set. He is VERY good about that!

 

[QRomo]

Nah, no need to have Tom go to the trouble. They sound fine other than the microphonics, and since I'm not in the habit of routinely tapping my amp their slight flaw doesn't really bother me.

 

[H0bbes]

Hello guys, long time lurker first time poster

 
A huge thanks to tomb for his excellent service, communication throughout the buying process and packaging.
Was really an enjoyable second diy project for me, here are some pics.
 
 
The package

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Nicely protected individual boxes
 

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Individual boxes
 

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Bubble wrapped individual boxes for further protection
 

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The sealed PCB nicely wrapped
 

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Unwrapped and unpopulated PCB
 

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I then cleaned the PCB with alcohol swabs
 

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Populated with resistors
 

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Fully populated PCB front view
 

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Fully populated PCB side view
 

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Back plate and hook up wires
 

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Input wires
 

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Side view with tubes
 

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Finally tube glows with star

 

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[jdkJake]

Sweet.

Awesome pictures! Your photography skills are most excellent.

Congrats and enjoy. What tubes are you using?

 

[H0bbes]

Thanks jdkJake
 
I'm using 12FM6s as recommended by tomb, regretted that I did not ordered any extra tubes to roll tho
 
Btw, since you have both MOSFET MAX and the miniMAX, how do they compare? I'm already itching for a third diy project 

 

[drclaw]

It's alive!!
 
I went over any suspicious looking solder joints and redid the VitQs.  Powered it up and it has worked since!
 
I reallly appreciate all of the help you guys have given me with this!   Thank you so much!!!
 
 

 
(I'll post some pics later)

 

[H0bbes]

Grats drclaw

 
I'm sure you'll enjoy the fruits of your labor

 

[tomb]

Quote:

It's alive!!
 
I went over any suspicious looking solder joints and redid the VitQs.  Powered it up and it has worked since!
 
I reallly appreciate all of the help you guys have given me with this!   Thank you so much!!!
 
 

 
(I'll post some pics later)

 
Quote:

Grats drclaw

 
I'm sure you'll enjoy the fruits of your labor

WOW - great news all the way around!  drclaw gets his fixed and H0bbes posts some great pics of his build, not to mention some very flattering pics of my shipment packing - thanks for that!!

 

 

[jdkJake]

Quote:

It's alive!!
 
I went over any suspicious looking solder joints and redid the VitQs.  Powered it up and it has worked since!
 
I reallly appreciate all of the help you guys have given me with this!   Thank you so much!!!
 
 

 
(I'll post some pics later)

 
That is great news drclaw. Enjoy!!

 

[jdkJake]

Quote:

Thanks jdkJake
 
I'm using 12FM6s as recommended by tomb, regretted that I did not ordered any extra tubes to roll tho
 
Btw, since you have both MOSFET MAX and the miniMAX, how do they compare? I'm already itching for a third diy project 

Good question, complicated answer. They actually sound a lot more different than I imagined they would. I am still listening to the MOSFET-MAX almost exclusively to form a valid opinion. So, these are just early impressions.
 
For my Grados, the MOSFET rules. There is no comparison. I would reach for it each and every time. It really matches up with those phones. For the Senn HD650, too early to tell as I just started listening to them with the MOSFET-MAX. At first blush, it seems a bit "thicker" if that is a word for it. Smooth with lots and lots of bass, but, far warmer and not quite as dynamic as the miniMAX. Again, I need more time on it before I comment further, but, the miniMAX seems a better match for the HD650. At least with my miniMAX configuration.
 
Now the complicated part. Not only are these two different amps in output buffers (MOSFETS vice 2SC2344/2SA1101 BJT's which report to have a brighter sound signature), I also have Black Gates at CA7. So, the entire output buffer is much different. The REALLY interesting thing to note is that I just discovered my miniMAX BJT's are under biased by a significant amount. While they are both exactly set to the same value, that value is 53mv, which is way under the suggested range. It has been that way since I got the amp. I only found this out this week when I pulled the board to check the transistors that were installed (I did not build it). 
 
So, what does this mean? It means I need to up my miniMAX bias and give it a good listen again. Hard to believe, but, it might even get better. 
 
The MOSFET-MAX is a great build of a great amp. I highly recommend it. It's nice to have the luxury of amps specifically targeted to a certain sound and headphone combo. What kind of phones are you using?

 

[H0bbes]

 
Quote:

 

WOW - great news all the way around!  drclaw gets his fixed and H0bbes posts some great pics of his build, not to mention some very flattering pics of my shipment packing - thanks for that!!

 

Your welcome tomb

 
Quote:

Good question, complicated answer. They actually sound a lot more different than I imagined they would. I am still listening to the MOSFET-MAX almost exclusively to form a valid opinion. So, these are just early impressions.
 
For my Grados, the MOSFET rules. There is no comparison. I would reach for it each and every time. It really matches up with those phones. For the Senn HD650, too early to tell as I just started listening to them with the MOSFET-MAX. At first blush, it seems a bit "thicker" if that is a word for it. Smooth with lots and lots of bass, but, far warmer and not quite as dynamic as the miniMAX. Again, I need more time on it before I comment further, but, the miniMAX seems a better match for the HD650. At least with my miniMAX configuration.
 
Now the complicated part. Not only are these two different amps in output buffers (MOSFETS vice 2SC2344/2SA1101 BJT's which report to have a brighter sound signature), I also have Black Gates at CA7. So, the entire output buffer is much different. The REALLY interesting thing to note is that I just discovered my miniMAX BJT's are under biased by a significant amount. While they are both exactly set to the same value, that value is 53mv, which is way under the suggested range. It has been that way since I got the amp. I only found this out this week when I pulled the board to check the transistors that were installed (I did not build it). 
 
So, what does this mean? It means I need to up my miniMAX bias and give it a good listen again. Hard to believe, but, it might even get better. 
 
The MOSFET-MAX is a great build of a great amp. I highly recommend it. It's nice to have the luxury of amps specifically targeted to a certain sound and headphone combo. What kind of phones are you using?

Wow, thanks for the lengthy comparison post, jdkJake.
 
So the MOSFETs version are more tube like than the BJTs?
The reason why I asked is because based on my very short time with the miniMax (less than 20 hours or so), it sounded a little bright or perhaps not as tubey like sounding as I envisioned it to be.
Perhaps I should let it burn in for a while more before forming an impression.
 
My BJTs are biased at 115mv and I also found that by varying the tube bias voltage it changes the sound a little bit.
With 13.5v dynamic range seems to be better and with 15v bass, details and imaging seems to be better but dynamic range suffers a little bit.
 
I agree, having a certain amps to be paired with a certain headphones is close to being in headphone/audio nirvana. Having said that I'm trying to setup the minimax for my grados/alessandros headphones. That is why I have 1000uf Nichicon Fine Golds at CA7 and RB14 jumpered after consulting tomb.
 
So it seems like I should get a MOSFET-MAX built, hopefully beezar.com will offer a MOSFET MAX kit when I'm ready to build one
I really hate caseworks, and not ready to invest in casework tools yet.
 
 

 

[jdkJake]

Quote:

 
 
So the MOSFETs version are more tube like than the BJTs?
The reason why I asked is because based on my very short time with the miniMax (less than 20 hours or so), it sounded a little bright or perhaps not as tubey like sounding as I envisioned it to be.
Perhaps I should let it burn in for a while more before forming an impression.
 
My BJTs are biased at 115mv and I also found that by varying the tube bias voltage it changes the sound a little bit.
With 13.5v dynamic range seems to be better and with 15v bass, details and imaging seems to be better but dynamic range suffers a little bit.
 
I agree, having a certain amps to be paired with a certain headphones is close to being in headphone/audio nirvana. Having said that I'm trying to setup the minimax for my grados/alessandros headphones. That is why I have 1000uf Nichicon Fine Golds at CA7 and RB14 jumpered after consulting tomb.
 
So it seems like I should get a MOSFET-MAX built, hopefully beezar.com will offer a MOSFET MAX kit when I'm ready to build one
I really hate caseworks, and not ready to invest in casework tools yet.
 
 

I have limited experience with all-tube-based headphone amps, so, I really cannot comment how the MOSFETs compare. I have read that is the case, but, do not have anything to back it up. The only all-tube designs I have heard were speaker amps. Certainly give it some more time. Especially the tubes. I have noticed that can take about a week or so to properly "wake up" after sleeping for so long on a shelf somewhere.
 
I would be surprised if Beezar makes a MOSFET kit as it is intended to be an experimenters platform, but, you never know. Certainly it is not hard to obtain the parts as the BOM is pretty complete. If you can build the amp, the BOM should not present an issue. It is more juggling out of stock parts and/or parts only available from a few vendors. Just be sure to check it multiple times before pressing purchase. It can really save on extra shipping that way. Shipping is the penalty you pay for mistakes/ommisions, which, I have paid on multiple occasions. 
 
The casework required is minimal, all you need is a drill and some rubber cement. The board is designed to fit in a standard case, you just need vent holes and jack holes. The MAX site goes into details on how it can be accomplished with a handheld drill. I even drilled the tube holes, but, I do have a drill press, vice and clamps available. Most of the tools can be rented for an afternoon if you really do not have them (including punch kits). The rubber cement is for the template method, which, works really quite well.
 
   http://www.diyforums.org/MAX/MAXcasework.php
 

 

 

[Beefy]

Beezar is unlikely to offer a kit, because of the casework. The pre-machined MiniMax case is what makes it such a great kit.