Wayne's BA 2018 linestage

[wdecho]

As did I, thanks for going to the trouble. Will solder up new boards tomorrow, with larger output devices.

As to my volume pot issues, I took one of my BA3 FE units out of service, removed the cover and compared wiring. There it is, wired inputs and outputs backwards!
All is working fine now. Whew!

Russellc

I am glad you persevered and did not throw in the towel. Congratulations.

 

[qwertyl]

A few sets.

Thanks Jim. I have just received the boards 🙂

 

[Russellc]

For such a simple circuit, I had fits with this build. Nothing wrong at all with the build it self, mostly done after work when tired and made some straight forward wiring errors, and mixed two caps up in wrong positions.

Now, all is good. It is dead silent, even when switching between inputs. The BA3 FE always has slight clicks when doing so. They are very slight or I would add on of those kits from Salas like I have in the DC3G build that uses relays to prevent them.

The off set problem is also abated, generally under 1 mV to 2 mV or so. Gain not as high as BA3 FE, but more than plenty.

Still need to "rebundle" the wiring with zip ties, had to undo to properly chase down connections.

 

[cpcornell]

Thanks Jim, My purple boards arrived yesterday, the same day as the Mouser order. A weekend of final four and preamps is in store.

 

[md_Stryker]

Received mine as well. Thanks Jim!

-Michael

 

[Russellc]

Installed the TubeCad Dual/Bipolar LV Reg. It’s really quite nice, slightly quieter then the 317/337 reg installed previously.

Thanks for this pic! Wasn't sure of correct orientation to install these larger outputs. This pic clearly shows how they go.

Russellc

 

[william2001]

Thanks to 6L6 I've got pcb's on the way along with parts from Mouser to try out this project. With the very low output impedance of this circuit, I had the thought to drive a Jensen JT-123-FLPCH wired as an autoformer into a stock F4 (has the jfet input buffer). Is something like this a reasonable idea? This is just a small bedroom system... I have the transformers already but would need to carefully remove them from my F6 boards. I currently drive the F4 with a BA-1 front end in it's own chassis with a shunt regulated supply.

 

[6L6]

Sounds like something worth trying! Let us know how it works and how you implemented it.

 

[Zen Mod]

decent xformer in signal chain is always good thing

 

[ThermalAlchemy]

MEPER, you could give that method a try although having a dedicated hot air gun you know exactly what temperature the air is at and how long. Maybe practice on some cheaper smd parts first to make sure your hot air attachment gets hot enough, but not so hot it burns the parts. That said, if I didn’t have the hot air gun I would just stick to the bamboo skewer and soldering iron method discussed earlier in the thread.



wdecho, this is the technique I used on these boards and it worked very well.

1. Clean your board(s) first
2. Put a small amount of solder paste on each pad and set smd parts on board. The solder paste holds the parts in place surprisingly well. I haven’t had a part blow away yet, no mater how small
3. Using the medium size tip, set hot air to 200C and fan speed between 5-6
4. Heat both sides of the board back and forth for about 30 seconds
5. Turn the heat up to 400C and concentrate the air stream more around the solder paste pads. When the solder melts it goes shiny and pulls the part into place perfectly on the pads

Sounds like you’re already good and ready to work with SMD Parts. When you’re a beginner learning you can never be too clean and having pre- soldered circuit board pads makes it so much easier . Having a good quality paste or liquid flux makes for a superior solder joint but you just have more cleanup with alcohol . Cannot know if you had a chance to go visit Mr. Carlson labs on YouTube I believe he dedicated two-part episode on soldering, of solder and flux and different types of soldering iron .

 

[jwjarch]

Sounds like you’re already good and ready to work with SMD Parts. When you’re a beginner learning you can never be too clean and having pre- soldered circuit board pads makes it so much easier . Having a good quality paste or liquid flux makes for a superior solder joint but you just have more cleanup with alcohol . Cannot know if you had a chance to go visit Mr. Carlson labs on YouTube I believe he dedicated two-part episode on soldering, of solder and flux and different types of soldering iron .

Yes, even after only a few boards I feel pretty comfortable with the hot air method. I used the chipquick brand paste and I’m very happy with it. And Yes! I’m a subscriber to Mr Carlson’s Lab on Patreon. He has a TON of great tips on soldering, restoring of old electronics, safety tips, you name it.

Made more progress on my boards this weekend as well. Fired up under 18V+/- and stabilized offset at +/-1mV. Can’t comment on sound yet but I’ll report back as soon as I get everything settled into a chassis.

 

[triode_al]

An externally hosted image should be here but it was not working when we last tested it.

Where is the soldering iron? 😀

 

[Zen Mod]

other side

🙂

 

[carsten.witt]

@Jim,
thanks for sending, arrived today! Did you put it yourself in my letter box and taking the airplane?

 

[Mr_Zenith]

Thanks, Jim! Received the boards Saturday - and promptly set about placing the appropriate orders... 🙂

 

[PJN]

Boards arrived. BOM ordered, thanks Jim and Wayne. Looking forward to hearing this pre.

Paul

 

[mpmarino]

Got to some soldering over the weekend. Ordered 10 fets. The first two I promptly lost 'flipping' out of the tweezers 🙂
Somehow got the last eight in without incident 🙂 (Hope I didn't cook any)

I've done some SMT ICs but nothing this small before - I'm too ham fisted and jitter challenged.

 

[Russellc]

Finished the "large output device" version of Wayne's boards. Where the cap and resister are left out, any jumpers required? Or just leave them flapping.

Russellc

 

[6L6]

Empty

 

[Centurion53]

Jim
Do you have any idea when the store may be getting the boards? I guess mine got lost in the mail.🙁