[Bullpride]

I am quite well equipped in the headphone amp department, but, I also want to learn to build 'em. So, I'll build a Crack+Speedball to start that journey.

In terms of parts/ performance upgrades, I think we have:

• Potentiometer - a good stepped attenuator can cost as much as the Crack, but an Alps pot seems a good balanced upgrade?
• Resistors - Looking for thoughts here. Looks like sometimes a choke is used in place of one resistor post power-supply to reduce power noise too. Hammond? Wire-wound replacements - Mills?
• Caps - You can spend quite a bit here. Some can also be huge. Looking for thoughts here.
• Anything else?

Question:
I assume it is best to build it to manual spec first (no changed parts), then make changes? Is that the case? Anything worth just doing during the initial build?

Chris,

I recently finished my build, and am asking some of the same questions you are.

1. Definitely build the stock crack first. Listen to it for a while. Then do the speedball. You can even do the speedball in stages. This has helped me start to recognize the differences in sound for each upgrade.
2. Potentiometer and Attenuators. There seem to be two suggested quite a bit:
One made by PEC
https://www.digikey.com/product-detail/en/KKA1041S28/KKA1041S28-ND/770961
The Alps Blue Velvet you mentioned:
https://www.parts-express.com/alps-...xte0RvVVRp4zTxgRciDFUTM59-A_3scRoCnikQAvD_BwE
3. Chokes - I think these fall under the "not necessary" category by the Bottlehead folks, but others suggest them
4. Caps - worthwhile upgrades, though I haven't done a lot of digging. The article below does a great job of outlining each of the suggested upgrades, with a decent break down of the individual Cap suggestions.
https://www.headphonesty.com/2019/04/upgrading-bottlehead-crack-headphone-amplifier/
5. I also found this article. The author commented on my post in "I love my Bottlehead" Group on Facebook. Moving one of the signal wires away from another group of wires cleaned up some noise I was hearing
https://www.hificollective.co.uk/bl...TyqZd_IqqNRs5S5pYOo5qtTTMObzAzVQaCDCnR1yX22Ec

This response is for you, but also so I have a handful of notes for myself, ha. The Bottlehead forum and this thread are an excellent source if you have additional questions. The folks on the forum are more than happy to help you troubleshoot.

 

[PsilocybinCube]

Quick question everyone - I am purchasing a 12au7 to 6sn7 adapter for my BHC with Speedball.

Can I simply drop in the tube and adapter? Do I need to do anything relative to the existing 12au7 socket?

I purchased this 2nd hand from DenverW and am still learning. I don't want to fry this baby!

On another note, I purchased a set of Hd800 headphones to pair with the BHC and will post some impressions later with different tube combos.

 

[Wes S]

Quick question everyone - I am purchasing a 12au7 to 6sn7 adapter for my BHC with Speedball.

Can I simply drop in the tube and adapter? Do I need to do anything relative to the existing 12au7 socket?

I purchased this 2nd hand from DenverW and am still learning. I don't want to fry this baby!

On another note, I purchased a set of Hd800 headphones to pair with the BHC and will post some impressions later with different tube combos.

Just drop it in, and enjoy. I just recently started rolling my 6SN7's with an adapter after a year of rolling all the best 12AU7's, and I will never roll another 12AU7 in my BHC again. The 6SN7 really takes things to another level, with the right tube combo.

 

[PsilocybinCube]

Just drop it in, and enjoy. I just recently started rolling my 6SN7's with an adapter after a year of rolling all the best 12AU7's, and I will never roll another 12AU7 in my BHC again. The 6SN7 really takes things to another level, with the right tube combo.

Well, I am freaked out. I tried out the adapter and the 6sn7 for about 10 seconds only to see a small amount of greyish/white smoke emitting beneath the adapter.

I purchased the adapter from what looked to be a good Ebay seller (I also have an order for one from a user here on Head-fi) but I wasn't willing to let it stay on once I saw that smoke. I requested their 6.3V option that they stated worked well with the BHC.

Am I being paranoid? Do I just need to let them run for a bit and see how it shakes out?

https://www.ebay.com/itm/GARAGE1217...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[Bullpride]

I haven't started rolling on my crack yet, but am considering it. I will probably make my way through the standard ones before using an adapter. Isn't there someone on Head-fi that makes adapters?

 

[chrisdrop]

I haven't started rolling on my crack yet, but am considering it. I will probably make my way through the standard ones before using an adapter. Isn't there someone on Head-fi that makes adapters?

@Deyan or xulingmrs on eBay

 

[Wes S]

@Deyan or xulingmrs on eBay

And Garage 1217, makes great ones as well, and you don't have to wait weeks for shipping, if you are in the States.

 

[Wes S]

Well, I am freaked out. I tried out the adapter and the 6sn7 for about 10 seconds only to see a small amount of greyish/white smoke emitting beneath the adapter.

I purchased the adapter from what looked to be a good Ebay seller (I also have an order for one from a user here on Head-fi) but I wasn't willing to let it stay on once I saw that smoke. I requested their 6.3V option that they stated worked well with the BHC.

Am I being paranoid? Do I just need to let them run for a bit and see how it shakes out?

https://www.ebay.com/itm/GARAGE1217-12SN7-6SN7-TO-12AU7-6922-TUBE-SOCKET-ADAPTER-TOP-BUILD-QUALITY/254102508696?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

I am using the same adapter, with zero issues. I have never seen smoke, and would be concerned. Maybe try a different tube. . .

 

[PsilocybinCube]

I am using the same adapter, with zero issues. I have never seen smoke, and would be concerned. Maybe try a different tube. . .

I should note that the smoke didn't appear to be coming from the tube, but just below the adapter, where it meets the amp.
If I turn on the amp with the adapter plugged in but no tube (to allow any residue on the adapter to burn off) will that damage the amp? Running just the power tube and the adapter to see if the smoke stops?
I would think that should be a safe approach, but again, I'm a neophyte.

 

[PsilocybinCube]

@Deyan or xulingmrs on eBay

@Deyan has made me an adapter...waiting on international shipping issues to get to the US

 

[Wes S]

@Deyan has made me an adapter...waiting on international shipping issues to get to the US

I am still waiting on mine too, and really hope to get mine soon.

 

[Wes S]

I should note that the smoke didn't appear to be coming from the tube, but just below the adapter, where it meets the amp.
If I turn on the amp with the adapter plugged in but no tube (to allow any residue on the adapter to burn off) will that damage the amp? Running just the power tube and the adapter to see if the smoke stops?
I would think that should be a safe approach, but again, I'm a neophyte.

Honestly, I don't think there should be any residue to burn off, and I wonder if they didn't send you the wrong adapter. Can you confirm it is the 6.3v version? I would get in touch with Garage 1217, and ask them if they know what is going on. There should never ever be any smoke.

 

[PsilocybinCube]

Honestly, I don't think there should be any residue to burn off, and I wonder if they didn't send you the wrong adapter. Can you confirm it is the 6.3v version? I would get in touch with Garage 1217, and ask them if they know what is going on. There should never ever be any smoke.

I requested the 6.3v but don't know how to confirm. I did touch base with Garage1217 to verify.

 

[PsilocybinCube]

I requested the 6.3v but don't know how to confirm. I did touch base with Garage1217 to verify.

Here's a pic of the underside of the adapter and the tube.

 

[Wes S]

Here's a pic of the underside of the adapter and the tube.

I will take a look at my adapters from Garage 1217 when I get home, to see if they look the same.