[tomb]

 

 
Yep - R4/R5 are the only RN60 resistors on the PCB.  Tough to get those mixed up.
 
OJNeg's help is greatly appreciated.  I agree that the CCS appears to be the issue.  Just for kicks - and this would be my fault - can you check the labels on the Q3 and Q4 transistors?  Make certain that they're "2N5087" and not "2N5088."  Also, check the MJE350's while you're at it - ensure that's what it says ("MJE350") on the front of those transistors.  I have tons of different transistors that go into Beezar kits.  It's possible I might have got them mixed up.

Q3/Q4 are correct, they are 2N5087, I am not sure about MJE350 yet, I need unscrew those first and check, I will update later today.
 
thank you all.

Unscrew them?  If you can't see the writing on the outside, then they're installed backwards.

 

[Iskandar Pane]

Tomb thank you for your quick reply en advice. Wsybok also thank you for posting the all pictures of your torpedo build. With the combination of the two I discovered my very S mistake. I swapped the polarity of C1!! Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice .

 

[OJNeg]

Tomb thank you for your quick reply en advice. Wsybok also thank you for posting the all pictures of your torpedo build. With the combination of the two I discovered my very S mistake. I swapped the polarity of C1!! Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice

.

You sure C1 didn't blow?

 

[Iskandar Pane]

Seems not, still in shape..

 

[tomb]

Tomb thank you for your quick reply en advice. Wsybok also thank you for posting the all pictures of your torpedo build. With the combination of the two I discovered my very S mistake. I swapped the polarity of C1!! Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice

.

 
 

 

Tomb thank you for your quick reply en advice. Wsybok also thank you for posting the all pictures of your torpedo build. With the combination of the two I discovered my very S mistake. I swapped the polarity of C1!! Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice

.

You sure C1 didn't blow?

 
 

Seems not, still in shape..

 
My guess is that it would've blown, too.  Non-bipolar, electrolytic capacitors rarely survive being soldered in backwards.
 
Still, this is the important point:
Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice

. 
 
 
Thanks for all the help, OJNeg!  Let's hope Wsybok has similar results!

 

[dsavitsk]

Seems not, still in shape..

Regardless, it needs to be replaced. It is not safe to use.

 

[dsavitsk]

Hey Doug, I've seen you mention the stoppers in a few posts across the web. Grid stoppers are pretty routine, but I haven't seen much mention of plate stoppers elsewhere. Its the plate's capacitive coupling to the inputs more of an issue in high gm tubes, or is it something else entirely? How would you go about sizing the resistors?

Frankly, it was a suggestion from Morgan Jones and SY that led me to do it. A very small value is sufficient.

 

[PretentiousFood]

Cool, I'll give it a go! I already have a sense resistor to monitor plate current, I'll just move it closer to the socket. Thanks for the reply.

 

[Iskandar Pane]

Replaced C1, safety first!

 

[tomb]

Just an FYI -
 
This is irritating, but the RCA jack assembly that was originally designed for the Torpedo is no longer made at Mouser.  I found replacements at DigiKey, but as it happens ... the Red Jack is on the top, but the Mouser version had the Red Jack on the bottom.
 
Solution: switch the patch cables from right to left.

 

[Daveze]

Just finished the construction of the amp and about to work through the test steps...just want to confirm the fuse value for 240v. Simple maths is 125mA, or is it not such a big deal and the 250mA should be fine?
 
By the way, seriously awesome build, looking forward to agreeing that it sounds amazing.

 

[tomb]

  Just finished the construction of the amp and about to work through the test steps...just want to confirm the fuse value for 240v. Simple maths is 125mA, or is it not such a big deal and the 250mA should be fine?
 
By the way, seriously awesome build, looking forward to agreeing that it sounds amazing.

Are you international and I didn't supply 125ma fuses?  Second question: they're all rated for 250V, could that be the number you're reading on the fuse?
 
Short answer is that the 250ma fuse will work, but will not provide the best protection.  You could fry the power transformer and the fuse would never blow.

 

[Daveze]

Hmm, I'm almost certain I read 250mA but you've got me questioning myself now...will confirm when I get home. 
 
The level of protection was my concern, not a fan of losing the power transformer...I wasn't sure what sort of margins were afforded with the nominated fuse.

 

[tomb]

  Hmm, I'm almost certain I read 250mA but you've got me questioning myself now...will confirm when I get home. 
 
The level of protection was my concern, not a fan of losing the power transformer...I wasn't sure what sort of margins were afforded with the nominated fuse.

I'm not saying I didn't make a mistake, but my regular practice is to check the customer's location and provide the fuses needed for the country's voltage ... and I write it out on the J3a parts package, as in "Fuse Drawer, Fuses for 230V line voltage (125ma)."

 

[OJNeg]

Just want to mention that on Saturday I got the chance to compare the Torpedo to both the BH Crack (stock) and the Schiit Valhalla2 with my modded HD800. I was surprised to find that the Torpedo bested both of them easily. Faster, more clarity, more microdynamics, etc.
 
So props to both Doug and TomB for providing what is probably the best ~$300-400 tube headphone amp out there.