Hi All,
Just wanted to share my experience in building the Bottlehead Crack with speedball upgrade. So first things first: The Crack build went smoothly and boy! was it great to hear. Did I mention that I used the Bottlehead Powercord also
.. Anyhows it sounded so nice that I was really hesitant to put in the Speedball upgrade. I was totally flummoxed at how that "warm" sound could be possibly improved upon. And like how curiosity killed the proverbial cat, this was the beginning of my troubles
It started with some unforseen disasters like the dog taking a shine to the Speedball boards
Finally after getting everything in place (see Initial Layout), the sound was absolutely flat. There was no hint of a strong bass, no warmth.. pretty ordinary. I had read other posts in the forum that say that it takes time to get used to the Speedball sound etc. etc. But my story was different. I just had to get back to the wonderful sound I had heard previously. So probing around and fiddling around with all the connections I found the problem to be in the 100uF caps. One of them was barely hanging by a thread and one of the leads came out at the slightest touch. After applying a ton of solder, freeing them from being underneath the board and rechecking for cold joints, it sounded so much better !! See the caps now in the Final Layout.jpg. The sound had improved so much, yet there was still something missing I felt. I had read everywhere else that bass becomes tigher and better. In my case I still had trouble picking up the bass lines especially while listening to rock.
I remembered that while I was troubleshooting the amp earlier, there was a static discharge in the output tube along (a blue spark) with a pinging sound. And after that, whenever I start the amp, the o/p tube hums for a few seconds briefly. So I replaced the o/p tube with a GE 6AS7GA and finally I feel everything has come together!!! Bass is so strong and discernible, the amount of detail I can make out in music is just staggering and instrument separation is very good. Here's a pic of the my rig right now (Final Build.jpg)
I hope my experiences come in handy for future builders! This is a great rig. Thanks in particular to Eilieen and Josh for sending me replacement boards promptly. I had a couple of questions on tube rolling though.
1. I was foolish enough to try tube rolling the input tube with a 12AX7. Thankfully I realized my mistake fast and turned off the amp within a few mins. Hopefully no long lasting damage
But can I replace the stock 12AU7 tube with a Tung-Sol 12AU7. I found a few of them reasonably priced at sites on the net (from $19-30).
2. My earlier stain and paint job on the Crack was pretty shoddy (and I think no one would disagree looking at the pic). Does anyone have suggestions on how best to lift the bad paint job and suggestions on how to do it better second time around.
Thanks again to the wizards at Bottlehead for this wonderful amp!!
