I don't know if this is of any interest however I have been mucking around with the whole quad 6BL7 thing for the past few weeks.
I have a love / hate relationship with quad 6BL7.
Love the sound. To me a single 6BL7 in a 6080 circuit sounds better than all the 6AS7G, 6080 and 7236 tubes I've tried however two per circuit even lifts that sound level again.
Hate the adapters and layout of tubes in the amp. The adapters are cheap nasty stuff. Don't even feel sturdy. So I have pulled these damn things apart and rebuilt. I've added more strength to the base. Basically added plastic wedges between the base and plate so now when that middle screw is tightened it grips the base and plate instead of the shaft going down the base. That shaft is a pain. If you move the plate around too much it loosens off. Then you have to remove the top and tighten being very careful not to break any wire connections. I've fixed this shaft a few times. From there I added some plastic wedges between the plastic bottom plate and the circuit board. As the bottom plastic plate can flex when the screw is tightened too much. The wedges keep it all straight. Now I have done this the whole thing is straight and feels far more solid. When putting in new tubes the adapter doesn't feel like it is going to break (no reports of it doing so).
After doing this the other things were location and making the adapters look more attractive. I think they are ugly.
Location.
In my amp with the wire grid adapters on my drivers I had a big problem. Personally I thought this layout looked the best (one 6BL7 directly behind the other) on my amp. However the front 6BL7's were too close to the driver grid wires and occasionally created an interference buzz in the wires. So no good.
I then did this.
Angled the adapters out a bit. Not as neat looking however it fixed the buzzing in the wire grids. Front 6BL7's are out of the way. Kinda got use to the looks now as well. Front tubes are all spaced out evenly (Rectifier, Drive and front power) and back 6BL7's are tucked in nicely in the corner of the transformers.
Shot from above:
So this worked well.
The above pic also leads me to the next thing I wanted to fix. The adapters look. This was my first attempt. I wrapped the adapters outside in carbon fiber wrap. Also did my other adapters to match. To make it look like a set. Carbon fiber wrap is just kinda like tape. A big sticker that looks carbon fiber. I purchased in A4 sheets and cut to measurements.
This wrap on the adapter kinda caused a problem tho. It got very hot. I think heat comes from that circuit board on the adapter. It might be a reason why it is open in design. To let heat out. When using like this the tape would separate in places around the adapter. Looked a little bad. When cooled down it went back to normal. However being OCD I wanted to fix. I was also concerned about heat build up in the adapter. There is no caps on that adapter board however I don't think it is a good idea to over heat it.
Here is my solution now:
Same tube arrangement. I've just made the adapters vent. Wrapped each adapter twice with the carbon fiber. Top and bottom but left the middle to vent. So far so good. No heat issues. Carbon fiber tape stays on. Doesn't separate and the adapter looks a lot better than standard.
So this past week I've got it to a place where I am happy. Adapter looks better and it is a lot stronger. No buzz from power tubes and the overall sound is better than a single 6BL7.
I nearly gave up on quad 6BL7 as the sound improvement is only a little better. Things do sound fuller and it sounds more effortless/relaxed. Seems to have more power as well. I have got there. I will roll with this for now.
End of rant. I don't know if this was helpful to anyone. More cosmetic and adapter strength than 6BL7 sound.
![20180505_101355[1005].jpg](https://cdn.head-fi.org/a/10109024.jpg)
