Hi fellow diy-ers. :wave:
Here is the VSSA all through-hole PCB as promised. (update- we now have our first SMD PeeCeeBee! :nod: Check at the end of this post)
Dimensions: 2" x 2.7".
There is no compensation capacitors and zobel on-board. If found to be necessary then the Zobel may be connected off-board at the binding post solder joints, and the Cdom(s) under the board between B and C of the VAS trannies. These accessories may find their place in the next version of the board, can't say for sure ;).
The resistors marked OFF1 and OFF2 are to be left for fine tuning of the offset. A value of between 100K and 1M at any of these will set the offset very close to zero. These should be connected after the board is fully assembled with all the other parts. Ideally any one of the two resistors will be needed. If connecting on the positive side seems to increase the offset then leave that and concentrate on the negative side only.
The amp can be run from +/-15V upto +/-35V. The only part that needs to be varied is the default 15K resistors which are for 35V operation. I Use 10K for my 16V setup. This value is best decided through direct measuring of the VAS current at the 10ohm degenerators at their emitters. 10mA is a good bias, with small "U" shaped heatsinks for the VAS. Increase to 20mA if you can keep them cold by using better heatsinks. The trannies are aligned so that a single metal piece can be used for both. Don't forget mica insulator if this is your choice.
Pix of my finished and assembled boards:
If you have any queries about the board and setup etc. then feel free to post it here. I'll help as much as I can.
edit:- The layout is in the VSSAbottom.pdf file.
Important:- Visitors/posters are welcome to modify any of the layouts according to their need and/or add totally new designs. However, if you want to use CCS or Multilayer Layout or Parallel capacitors in the feedback network then please post your VSSA experiment and results in the original VSSA thread. Link >Here<. This thread's topic is single layer printed circuit board designs based on the VSSA schematic without the above mentioned accessories, shown in one of the pictures attached below. Thanks for your co-operation.
More Tested PeeCeeBee designs(kind contribution by fellow diy-ers):
1. By PMI:- Click >Here< (Pro-style layout with under-board MOSFET mount).
2. By Jason:- Click >Here< (TO3 output MOSFETs)
3. By dobrivoje:- Click >Here< (large onboard input film capacitor)
4. By John:- Click >Here< (old-school hand-drawn layout with curves)
5. By Damanhuri:- Click >Here< (Spacious layout with a lot of on-board PS decoupling)
6. By Olafk:- Click >Here< (Lovely Looking SMD PeeCeeBee)
Some o'scope shots of PeeCeeBee performance:
1. By PMI:- Click >Here<
2. By nicos:- Click >Here<
Thank you Shaan!:cool:
Very nice job!:cheers:
Shaan, you're a caring friend.:up:
You have a big heart, :nod: thank you for all the kindness!
More power to you!
Great Shaan! Thank you for giving us another option!
Many Thanks Shaan! :)
Just 2 questions:
Why did you take out the CCS?
How much capacitance would you use with 35V rails?
Thank you again for your kind and good work!:)
Way to go Shaan!
Very generous of you.
Thanks all for the appreciation. I hope the design will serve its purpose.
1. No CCS as performance is already excellent witout one.
2. About 15000uF per polarity for two channels.
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