I have looked at the high quality multilayer ceramic's from vishay and others. I will use these for any decoupling.
On the IPS boards ... ALL SMD , I can even use 2.2uF 25V for the servos and 12V regulators . But 2.63$ is a bit expensive for the 2.2's !! https://www.vishay.com/docs/45199/vjcommercialseries.pdf 1uF (1.65$) could work for both these circuits by increasing resistance for the same R/C constant.
Most of the ripple rejection will be on the OPS board where I can use the cheaper through-hole electro's.
This is why I designed for such low power dissipation. IPS's will just be big high voltage op-amps ... drawing 15mA per rail.
C0G would work , but the pads could also take the silver mica's - builders choice. SM SMD's go for 4+$ per chip , glad there is only 2
per channel !
OS
Yes , I want 6 of these. 2 for my 8" 2-way party speakers .... they don't have any amp now. I might replace the plate amp for my sub. And
2 more for my self powered satellites. The one left over , I could prebuild IPS's for those that are too scared to jump on the SMD train.
2 more for my self powered satellites. The one left over , I could prebuild IPS's for those that are too scared to jump on the SMD train.
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Considering the total budget needed to build a quality amp, mentioned $16 is not worth it to compromise on capacitor quality. Stay with SM.
The front-end should fit into this space. I did a similar SMD design and it took up about 5x5 cm with most components on one side. If you put more components on the bottom, then it should be even easier. I tried to keep most components on the top for serviceability reasons.
In part , this is why I decided to make the OPS (almost) all SMD. Some through-hole components are still superior to their SM equivalents.
- Transistors ... SMD might be better , more choices and better more modern processes. Shorter trace paths are cool , too.
I have about a dozen candidates with 120-180V Vce / 100Mhz / <15pF Cob for HV devices. almost TOO many choices for small signal devices.
-Big resistors , TH (through-hole) might be better because of the part of being in the air. Wow , .05% precision resistors ... https://www.digikey.com/en/products/detail/vishay-dale/TNPU040249K9AYEP00/10668515 , It's just sticker shock to pay 2$ for something as
big as a grain of rice.
Caps - These... https://www.digikey.com/en/products/detail/cornell-dubilier-electronics-cde/MC12FD330J-F/776247 are the silver mica's I'm designing
for. CDE has some 100V silver mica's @ $0.80 , but no one stocks them.
<1uF (and .1uF) 21 million .10c units in stock - https://www.digikey.com/en/products/detail/samsung-electro-mechanics/CL03A104KQ3NNNC/3886671
Here is a candidate , $2.67 for 47pF .... these amps might just lose a few ppm at 20Khz with this value. 47 is a more common value , cheaper and more choice
@500V - https://www.digikey.com/en/products/detail/cornell-dubilier-electronics-cde/MC12FD470J-TF/1921349 . Mouser has them , too.
I really can't use 100V SM's (real cheap) , because the VAS B-C has full rail swings .... I'd be pushing it !!
For the OPS , I can buy those 22pF@500V 12 for 5$ on ebay !! glad it is through-hole.
So many choices , glad I have a fast PC - lot's of tabs open !!
OS
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Indeed, those who put in some time will be able to find these price jewels. It's part of the hobby to seek for them. I have a local source offering small quantity's CD silver-mica e.g. 47 and 100 pf 500 V as low as € 0,41 ex VAT. The less limitations on component choice the PCB design dictates, the better the odds to find something beautiful.
Thank you for all the time and effort you put in these projects, it's highly appreciated.
It will be a tight fit, the problem with having too many components on the bottom side is you breakup the ground plane then having to resort to a four layer pcb, this is okay for a design that is a daughter board, on a single board you now have ground planes running into the high current area of the output stage and having to segregate the high current return paths from the input stage current return paths.
These are not criticisms of a particular pcb, but are decisions that form part of the engineering processes and design criteria.
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OmeEd, I might know your local supplier also, but are you sure you are talking about CD silver mica's ? I think they are the unbranded mica's, and do we really know their quality ? I bought my CD 470pF mica for the Wolverine in that store, they had to backorder and since then the price went up... But I agree with some searching in different stores you can bring down the parts costs.
Finished the OPS. 1 pair 60W... both pairs 100W @ 53V rails (My trafo).
OPS is the "OST-mini" precision EF3.
Now for the 3 IPS's !!! (Spooky , Hellraiser CFA , and "blameless") .
2'nd pix is the blameless , a P3A on steroids. Crazy PSRR , no servo - simple 2PPM IPS.
OS
OPS is the "OST-mini" precision EF3.
Now for the 3 IPS's !!! (Spooky , Hellraiser CFA , and "blameless") .
2'nd pix is the blameless , a P3A on steroids. Crazy PSRR , no servo - simple 2PPM IPS.
OS
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Either on top or at a right angle (up and down). Should be able to fit in any EBAY E- waste amp case. I have 2 "for parts or not working" cases.
I'm also going to make a rectifier/filter cap board (also 75 X 150mm). Rails and +/- 24V series regulated for any accessories. Final regulation will be on the
accessory boards (lm78L12 , 79L12 , 78L05) ... just 25c each. Power board will also have the fuses.
OS
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Regarding your OST_mini PCB layout. What about putting C114/116, V+/GND/V- terminals between the two sets of transistors? i.e. slide this section into the middle of the PCB, shove the other stuff left a bit to make room. This would shorten the high current tracks to the output stage and put the storage where it's needed the most.
Hi os,
Have you decided to go for output transistors in configuration N P N P and in one line after you've seen my PCB layout posted here, just curios?
Q104 goes out on leads , they are doing it on the wolverine even as I did design it under- board.
Being out on leads they still get sub ppm. Mount Q104 either on Q110 or on the HS between Q109/110.
OS
I not sure who did what first ?I designed the Wolverine in 9/21 with P/N/P/N/P/N. I was not aware of your layout at that time. The Slewmaster
was not like this and I measured hotter HS temps at the top ,,independently decided to do both alternating genders and rail cancellation in the
next design (Wolverine). I should search out all your threads to harvest the "secret sauce" from them - good work !!
I actually first saw P/N/P/N on a PASS amp Google photo first....
OS
I just used the Wolverine type layout ... have you seen the THD/IMD/Noise figures ?? Why screw with perfection ?
.00002% 1k / .00008% 20khz -115db+ noise...
also , if you mount the boards horizontal , you still have to reach the screws on the outputs and Vbe - caps have to be out of the way.
Ripple filter caps can be 12mm tall 47uf @ 63V Nichicons. Using TTC/TTA004"s (170Hfe - tested on the wolverine thread) , you would have
6800uF+ equivalence per rail for the IPS supplies.
OS
I saw that in a Perreaux amp in the 80's. Not saying they were first but it's at least a 40yo innovation
Finalized my SMD component choices -
Trannies =
-2SC3649/2SA1419 - SOT89 - for HV VAS duty on all IPS's - https://www.mouser.com/datasheet/2/308/1/EN2007_D-2311156.pdf -$0.80
-BC817/807 - SOT-23 - for all LTP's and diamond pairs. - https://www.mouser.com/datasheet/2/916/BC807_SER-1594290.pdf - $0.18
-2SC2713/2SA1163 - SOT-23 - medium voltage for regulators and cascodes. Replaces the 2sc1845/2sa992's - better gain/Cob ... Toshiba !! $0.34 https://www.mouser.com/datasheet/2/408/2SC2713_datasheet_en_20220308-771444.pdf
Output stage - standard TTC/A 004's for 1A , MJE15030/31 for 8A , and NJW0281/0302 @ 15A
MJE's don't seem to outdated and are pretty cheap ... $1.71
Led's have 1000's of choices - I need 1.7V to match that LT QTLP690 red model I use. My led's actually do something besides
shine .... CCS's and the cascode need to match that 1.7Vf and have the opposite Tc of the BC817/807's.
At least SMD has so many (red) choices .... but nowhere as many as white led's - WOW !!
https://www.mouser.com/datasheet/2/109/smt_selector_guide-1163647.pdf
Have not decided on servo op-amp's yet. It's not in the audio path (some have debated that).
I only need one with low current demands , cheap standard ... does not even need to be Jfet.
TI OP07x - SOIC-8 - is cheap $1.15 - https://www.ti.com/lit/ds/symlink/o...454487&ref_url=https%3A%2F%2Feu.mouser.com%2F It draws <2mA per rail @ 12V. Good !
Just need to find a standardized package for single op-amps - there are 161 choices at Mouser !!
This is easier than I thought (layout).
I see that they do a lot of device matching in the Wolverine thread. they have the BC807/817-duals at 1% matching .
https://www.mouser.com/datasheet/2/916/BC847BS-1369707.pdf .. same low Cob/high gain as the singles in SOT363.
Not to tiny !
Good to go , all links saved for tweaking the packages and pinouts.
OS
Trannies =
-2SC3649/2SA1419 - SOT89 - for HV VAS duty on all IPS's - https://www.mouser.com/datasheet/2/308/1/EN2007_D-2311156.pdf -$0.80
-BC817/807 - SOT-23 - for all LTP's and diamond pairs. - https://www.mouser.com/datasheet/2/916/BC807_SER-1594290.pdf - $0.18
-2SC2713/2SA1163 - SOT-23 - medium voltage for regulators and cascodes. Replaces the 2sc1845/2sa992's - better gain/Cob ... Toshiba !! $0.34 https://www.mouser.com/datasheet/2/408/2SC2713_datasheet_en_20220308-771444.pdf
Output stage - standard TTC/A 004's for 1A , MJE15030/31 for 8A , and NJW0281/0302 @ 15A
MJE's don't seem to outdated and are pretty cheap ... $1.71
Led's have 1000's of choices - I need 1.7V to match that LT QTLP690 red model I use. My led's actually do something besides
shine ....
CCS's and the cascode need to match that 1.7Vf and have the opposite Tc of the BC817/807's.At least SMD has so many (red) choices .... but nowhere as many as white led's - WOW !!
https://www.mouser.com/datasheet/2/109/smt_selector_guide-1163647.pdf
Have not decided on servo op-amp's yet. It's not in the audio path (some have debated that).
I only need one with low current demands , cheap standard ... does not even need to be Jfet.
TI OP07x - SOIC-8 - is cheap $1.15 - https://www.ti.com/lit/ds/symlink/o...454487&ref_url=https%3A%2F%2Feu.mouser.com%2F It draws <2mA per rail @ 12V. Good !
Just need to find a standardized package for single op-amps - there are 161 choices at Mouser !!
This is easier than I thought (layout).
I see that they do a lot of device matching in the Wolverine thread. they have the BC807/817-duals at 1% matching .
https://www.mouser.com/datasheet/2/916/BC847BS-1369707.pdf .. same low Cob/high gain as the singles in SOT363.
Not to tiny !
Good to go , all links saved for tweaking the packages and pinouts.
OS