Crack;Bottlehead OTL

[NightFlight]

  Awesome thanks for the links!
 
Is there any harm in using 12bh7's without doing these mods? I had been under the impression that with the speedball in place it was safe to use them, just want to make sure though.

 
From what I've read I gather the beefier transistor has a much better safety margin because the 12BH7 is pulling more current. That is discussed in BH thread I linked. Review that for confirmation.

 

[i luvmusic 2]

I bypass the last 220uf caps with a SOLEN 2.2uf it did  add a little treble,It sound nice for the HD650 but not for DT880 600 ohms it's bright.

 

[Maxhawk]

Curious which tube do people find have the most affect on sound? Power or input?

 
Theoretically the input tube should have more of an effect because that's where the gain is, but since there's only 2 tubes, both have a noticeable effect on the sound. In my experience, the input tube makes the biggest difference overall, but the output tube has a larger effect on bass because it controls the output impedance. I've been happiest overall with a 5687 at the input, but it has a different pin-out which I address using a 4PDT switch to change the wiring. This tube most certainly requires the speedball constant current source as well as swapping its stock MJE350 for an MJE5731 since it pulls a lot of current and it gets really warm under the hood.

 

[Demoninja]

Anyone have any tips for isolating my BHC? I have a bit of static coming through the amp and I've identified it to be my power line adapter causing it rather than any construction issues. I need the power line adapter because my wifi signal doesn't reach my room.

 

[FunyunBreath]

Maybe an isolation transformer would help?
 
I keep my amps plugged into this and it does the trick as far as removing noise from the shoddy electric in my apartment:
 
http://www.amazon.com/Tripp-Lite-Isolation-Transformer-Outlet/dp/B00006HPFH
 
Since it's Prime on Amazon you could always try it out and return it if it doesn't work for you.

 

[NightFlight]

  Maybe an isolation transformer would help?
 
I keep my amps plugged into this and it does the trick as far as removing noise from the shoddy electric in my apartment:
 
http://www.amazon.com/Tripp-Lite-Isolation-Transformer-Outlet/dp/B00006HPFH
 
Since it's Prime on Amazon you could always try it out and return it if it doesn't work for you.

 
Hilarious. I have a Tripp-Lite ISO unit as well. Snatched up for $5 from Value Village!  Recently I gutted it and pulled out the protection circuitry. I think all the internal runs are 14AWG, which is plenty, but I'm still considering getting rid of all the jumpers and soldering it instead and get rid of all those brass to copper transitions.
 
But for electrical noise, I've found it works well that way too. 
 
Then I found out my input tube was triggering a horrible ringing in one channel at ~16-18Khz range once fully warmed up.  It was weird to hear it coming from the headphones.... then unplug the headphones and still hear it. The amp was literally screaming! Kinda like coil whine.  Swapped the input tube and the problem went away *fingers crossed*   It had better not be my output tube. Because its my precious....

 

[hdtv00]

Man stop, don't even be letting me hear nightmare tube stories. I just today got my first Western Electric 421A and I don't want to hear any bad tube stories. It gave me a chill.
 
Although that said it's nice to know hear a story of something that might or might not happen to a crack so we're not freaked totally out if it happened to us. Precious and *fingers crossed, indeed*.

 

[Demoninja]

  Maybe an isolation transformer would help?
 
I keep my amps plugged into this and it does the trick as far as removing noise from the shoddy electric in my apartment:
 
http://www.amazon.com/Tripp-Lite-Isolation-Transformer-Outlet/dp/B00006HPFH
 
Since it's Prime on Amazon you could always try it out and return it if it doesn't work for you.

 
The price on that seems a bit much. I'll probably see if there's anything else I can do. I think I would rather sell the BHC and get another amp than to spend another 125.

 

[JamieMcC]

  Anyone have any tips for isolating my BHC? I have a bit of static coming through the amp and I've identified it to be my power line adapter causing it rather than any construction issues. I need the power line adapter because my wifi signal doesn't reach my room.

 
I had a similar issue with a power line adapter when steaming from my lap top to dac with the low level static back ground fluctuations matching the flickering of the LED on the power line adapter perfectly. Strangely this only happened when streaming from one laptop and not a couple of other devices I also use and it disappeared if I connected the same laptop to my dac via usb.
 
I have since moved my digital library to a small desk/net top pc and now have it connect via optical which has been worked well for me.
 
A bit or trial and error I guess is the answer.

 

[daltonljj]

Just got my HD800 today after 2 years of eyeing on them. Paired it up with the crack which I built it prior to the purchase of the HD800. I must say the results are just simply spectacular. No hissing noise just pure music enjoyment to my ears. I've tried the hd800 with other tube amps that are in the range on 2000-5000 and I have to say this pairing is definitely comparable if not better than some. Doubt i will need an amp upgrade anytime soon. Mainline maybe 

 ???

 

[Maxhawk]

  Doubt i will need an amp upgrade anytime soon. 

 
Do you have the speedball upgrade?

 

[daltonljj]

   
Do you have the speedball upgrade?

yupp i do ... haha

 

[mcandmar]

Power line adapters, ugh.  As an IT guy the very thought of plugging a network cable into a power socket sends chills down my spine

 

[JamieMcC]

  Power line adapters, ugh.  As an IT guy the very thought of plugging a network cable into a power socket sends chills down my spine

If it was only powerline adapters that cause problems, my car alarm will knock out my wireless signal. With the car on the drive press the key fob to lock the doors and bam signal drops out unlock the doors wifi works again!  Guess that's life and you cant have it all.... 
 
Edit actually if everything was working perfectly I think I would be worried something bad was about to happen as it definitely wouldn't be normal

 

[atomicbob]

Replaced the 22K plate resistors on the 12AU7 with Bournes 50K 1W 25 turn trimpots to accommodate multiple input tube types in a non-speedballed Crack. Currently have a Tungsram E80CC as input tube. When this sucker reaches 88 volts, you're going to hear some serious ****. E80CC plate to 6AS7g grid. (with apologies to Back To The Future.)