[BK_856er]

Another one lives!
 
Final wiring was a real pita in the small case, but I think it turned out well.
 
Sounds really great on an initial listen with a bugleboy tube and my testing headphones.  Still need to put it through its paces and do the shakedown thing, and also finish the perf top.  Mute circuit kicked in a few times when adjusting the pot up or down quickly.  Didn't get any meaningful voltage between pins 1 and 6 during the powerup tests, but the amp still seems to work fine.
 
[edit:  So apparently I should have been measuring pin 1 and 6 separately against SG.  Brain does not function at 100% after 1AM.  Changed out the initial tube and no more issue with the e12 circuit.  Also zero hum/noise at any pot position with music paused.  Nice!]
 
[edit#2:  The initial tube I mentioned above was getting 12.6V instead of the 6.3V that it was designed for...that probably explains the initial e12 quirks with quick volume changes...and the really bright heater filament glow.  Doh!  Everything is cool at 6.3V and the e12 circuit is now perfectly behaved.  I need to lay off the late night testing.]
 
Here are some initial pics.
 
BK
 

 

 

[cfcubed]

Looks good BK, like the right-angle wiring - nice way to dress it up.  Great it sounds good & works well too

 

[Mullet]

BK ~ looks great! Can't wait to see that silver perf top. Wiring looks cool as well. I guess I'm a little lazy with the wiring. Maybe it's because wiring the thing up is definitely a PITA and I just want to get the dang thing over with.
 
Here's a pic of my latest creation. It turns out as of my last posting I had a defective L1H and I zapped my Q3P in the process of troubleshooting the L1H. Once I replaced these parts all was fine. I like the look of the silver knob/perf top better than the all black.
 

 
I didn't want to take a pic of the back because I slightly screwed up the placement of a hole or two. Anyways, if anyone has an extra undrilled panel or two that they don't need that would be killer. PM me.
 
With this build I went with the BOM caps. I had two Russian PIOs, but I couldn't get the leads correct and accidentally broke them off. What a waste. So I ended up with the BOM caps this time. Maybe I'll get what BK put in his CTH and drop them in later on. What caps are those again? They look easier to install than the Russian PIOs.
 
Cfcubed... do you know if there is a difference in sound quality between the squarer and more taller Wima caps you sent me vs. the shorter and rectangular BOM Wima caps? Both are .22uF and I think 100v.

 

[BK_856er]

 
Quote:

 
With this build I went with the BOM caps. I had two Russian PIOs, but I couldn't get the leads correct and accidentally broke them off. What a waste. So I ended up with the BOM caps this time. Maybe I'll get what BK put in his CTH and drop them in later on. What caps are those again? They look easier to install than the Russian PIOs.
 
Cfcubed... do you know if there is a difference in sound quality between the squarer and more taller Wima caps you sent me vs. the shorter and rectangular BOM Wima caps? Both are .22uF and I think 100v.

I have some info back on page 6 or 7.  I used Auricaps from Audience in my build.  The Sonicap GenII is going to be the easiest botique cap to install due to its relatively small size and solid leads.  I purchased both types through SonicCraft.
 
BK
 

 

[cfcubed]

Quote:

Cfcubed... do you know if there is a difference in sound quality between the squarer and more taller Wima caps you sent me vs. the shorter and rectangular BOM Wima caps? Both are .22uF and I think 100v.

Really doubt you'd hear a diff between those 0.22/100V WIMA Polyester Film box caps... The ones I sent are older & perhaps a different series (they're always making caps more compact).
IMO w/my ears & music it would take a much bigger diff in cap/cap design to notice a difference.

 

[civilmonkey]

Update to DT880/600 ohm and e12 latching / unlatching:  I put in a 12BH7A tube (the tube I happened to buy was described as a RCA Black Plate).  The occurance of unlatching at high volumes has significantly reduced.  Aside, the sound is incredible and I can't stop listening to it.

 

[Mullet]

 

I have some info back on page 6 or 7.  I used Auricaps from Audience in my build.  The Sonicap GenII is going to be the easiest botique cap to install due to its relatively small size and solid leads.  I purchased both types through SonicCraft.
 
BK
 

Cool... I'm thinking of going with the Sonicap Gen IIs. They look to be the most bang for the buck and I'm not looking to deal with a PITA installation.

Really doubt you'd hear a diff between those 0.22/100V WIMA Polyester Film box caps... The ones I sent are older & perhaps a different series (they're always making caps more compact).
IMO w/my ears & music it would take a much bigger diff in cap/cap design to notice a difference.

I'm with you on not noticing the difference. My ears are by no means golden. And if both are made of the same type of material then that would make sense that they sound pretty much the same.

Update to DT880/600 ohm and e12 latching / unlatching:  I put in a 12BH7A tube (the tube I happened to buy was described as a RCA Black Plate).  The occurance of unlatching at high volumes has significantly reduced.  Aside, the sound is incredible and I can't stop listening to it.

I get similar unlatching with both my 250ohm DT880s and Senn HD650s at higher volumes. I'd say this happens at 1 o'clock or 2 o'clock on my pot. I'd never listen at these listening levels anyways. I'm using the blue velvet pot, so I'm not having it trip in the same fashion as you are.

I'm wondering about those 12BH7 tubes. I've read fantasic things in general, but nothing in terms of what's *the tube* to get. I've got a bunch of RCA tubes in general and want to try and move away from them to explore something new. I've heard pretty good things about Tung Sol, but they're typically more expensive @ $60 a pop. The RCAs are 1/3 the price. I was gaming for a pair of Brimar 12BH7, but I wasn't willing to pay $80 for the pair. I'm trying to stay lower than $30 a tube now that I've spent way more on a few select tubes like the Siemens CCa and chrome plate 12AU7s. At this point I'm looking for a good price on the Telefunken E88CC.

 

[kiwiluke]

Mouser does not have the amp CRD's (2.0 and 4.3 mA) as specified in the BOM.  Will the 2.2 mA (1N5306) and 4.7 mA (1N5314) diodes be suitable replacements?

 

[Garage1217]

Missed the buy.. DOH! Any boards left?

 

[BK_856er]

Just about have things wrapped up with this build!
 
I swapped my EHHA RevA with particleman14's most excellent Beta-22 so we could each audition at length.  I thought the CTH size comparison below was amusing...
 
BK
 

 

[sachu]

that CTH amp is a pint sized pinch hitter

 

[cfcubed]

Quote:

Mouser does not have the amp CRD's (2.0 and 4.3 mA) as specified in the BOM.  Will the 2.2 mA (1N5306) and 4.7 mA (1N5314) diodes be suitable replacements?

My guess is that you can go slightly under or slightly over (as above) if you must for these, but preference would be for using the spec'd values if they could somehow be found of course.
Another guess is that if you had to use non-spec'd values, considering plate curves, go slightly under for the tube (1.8mA) and slightly over for the OB (4.7ma).
You could ping runeight about this to see what he thinks.
 
BTW for those using same input as output jacks consider trying to label them somehow (e.g. rub-on white lettering, a simple I & O ?). 
Seems the CTH most often survives brief errant swapping of these but it's not something I'd bet on.

 

[runeight]

Sorry gents, I am pretty consumed right now getting the LFs out.
 
Chris' CRD suggestion is just about right. You can use 1N5314 instead of 1N5313 and you can sub 1N5304 for the 1N5305. The 1N5306 would be second choice but probably ok too.

 

[kiwiluke]

Thanks for that.  As the 1N5304 is also not available at Mouser, the 1N5306 will have to do.

 

[BK_856er]

Picked up a couple 12BH7A tubes today locally.  Might be my new favorite!  One is a General Electric and is punchier, but has some microphonics.  The other is a little more subdued in its presentation, although still VERY nice.  It's labeled as "Made in Japan" and "Product of xxxSTROM"  where the xxx are rubbed off letters.  Anyone know the manufacturer?  No microphonics.  Killer glow from the top and bottom.  The lower amplification factor is helpful for sensitive cans.  There are a few more available if anyone (mullet?) is interested.
 
Based on the reminder from cfcubed about inputs/outputs, and recognizing that this is going to my non-DIY brother, I added some good labeling.  In retrospect the 1/4" jack would have been a safer route.  The "reveal" is next week!
 
BK