Xmas Amp - Dibya's TDA7293 by Jhofland

[e_fortier]

Hi X

My plan is to use a nice audio type SMPS rated +/- 39 Vdc, can I still use the on-board DC servo from the amp or are the rails voltage slightly too high (above 35Vdc) ?

Thanks
Eric

 

[Dibya]

Hi , LM317/LM337 can take max 40V input , that will be cutting too close.

By the way 7293 isn't SMPS friendly if rail voltage on one side not equal to other side , 7293 can blow. Ofcourse error within 1v is fine.

 

[xrk971]

You can skip the DC servo and LM317/337 if desire to use higher rail voltages. There is an LM317HVT (60v) but not the equivalent negative LM337HVT.

Technically, +/-39v is under +/-40v but you may be close to an over voltage situation if the mains voltage varies if the SMPS is not regulated.

 

[e_fortier]

Thanks Dibya

The SMPS is from Cresnet and pretty accurate, for the regulators i could use the 3x7HV type.

Maybe I’ll build a linear type. Thanks for the heads up.

Happy Holidays
Eric

 

[Dibya]

Hi xrk,

I got cheaper but better components for Linear PSU.
Those Chinese nover caps shall be avoided at any cost. Worser ear than even Samxon and Samwha.
I believe everyone has proto board lying around somewhere

4700uf 50v x 4
​​Access to this page has been denied.
​
​GBJA1502-BP Diode Bridge
​https://www.mouser.com/ProductDetai...-MCC/GBJA1502-BP/?qs=ahcBuItHZ3ykSdUget89ng==
​
​470nf Capacitor

​https://www.mouser.com/ProductDetail/Panasonic/ECW-FE2J474KA/?qs=wYonFgBYHKkV/7JwdBfsaA==

 

[Dibya]

Hi Everyone ,

If anyone not running out of budget for psu then All Cee CRC pcb by xrk971 can be used or my emerald CRC pcb (if you don't mind proto board)

 

[xrk971]

Hey folks,
I just got word from the moderation team that the best way is that I create a new thread in Swap meet to handle the board giveaways using PM’s and email. We can do that once we reach 50 boards (25 people). I’ll just copy the list of names to a new swap meet thread and we will take it from there. We can keep the list going here for now to prevent confusion.
Thanks,
X

 

[chermann]

I would like a pair also.

MaxReboBand / 2 boards / USA
as8912 / 2 boards / USA
ahtllc / 2 boards / USA
dBel84 / 2 boards / USA
Flamethrower1 /2 boards/ USA
Signal Lost / 2 boards / USA
diy.tiger / 2 boards / NZ
MShipmanPE/ 2 boards / USA
Angchuck / 2 boards / Singapore
Francois G / 2 boards / USA
Asuslover /2 boards /USA
Guerilla / 2 boards /Denmark
astromo / 2 boards / Australia
Kay Pirinha / 2 boards / Germany
pinkfloyd4ever/ 2 boards / USA
Sixto / 2 boards / USA
Tubesguy / 2 boards / USA
E_Fortier / 2 boards / Canada
Hicoco / 2 boards / France
Liva / 2 boards / Canada
Kokanee / 2 boards / Canada

Thank you to the design team
__________________

wow..thx


i am in..
chermann/ 2 boards / Austria

 

[twocents]

I would like a pair also please. I need a new project to kick off 2021. Thank you X and team!

MaxReboBand / 2 boards / USA
as8912 / 2 boards / USA
ahtllc / 2 boards / USA
dBel84 / 2 boards / USA
Flamethrower1 /2 boards/ USA
Signal Lost / 2 boards / USA
diy.tiger / 2 boards / NZ
MShipmanPE/ 2 boards / USA
Angchuck / 2 boards / Singapore
Francois G / 2 boards / USA
Asuslover /2 boards /USA
Guerilla / 2 boards /Denmark
astromo / 2 boards / Australia
Kay Pirinha / 2 boards / Germany
pinkfloyd4ever/ 2 boards / USA
Sixto / 2 boards / USA
Tubesguy / 2 boards / USA
E_Fortier / 2 boards / Canada
Hicoco / 2 boards / France
Liva / 2 boards / Canada
Kokanee / 2 boards / Canada
chermann/ 2 boards / Austria
twocents/ 2 boards / USA

 

[xrk971]

Wow, only 2 more people to go (4 more boards)!

 

[s610adam]

Thanks! This is so nice, I'm in for 2

MaxReboBand / 2 boards / USA
as8912 / 2 boards / USA
ahtllc / 2 boards / USA
dBel84 / 2 boards / USA
Flamethrower1 /2 boards/ USA
Signal Lost / 2 boards / USA
diy.tiger / 2 boards / NZ
MShipmanPE/ 2 boards / USA
Angchuck / 2 boards / Singapore
Francois G / 2 boards / USA
Asuslover /2 boards /USA
Guerilla / 2 boards /Denmark
astromo / 2 boards / Australia
Kay Pirinha / 2 boards / Germany
pinkfloyd4ever/ 2 boards / USA
Sixto / 2 boards / USA
Tubesguy / 2 boards / USA
E_Fortier / 2 boards / Canada
Hicoco / 2 boards / France
Liva / 2 boards / Canada
Kokanee / 2 boards / Canada
chermann/ 2 boards / Austria
twocents/ 2 boards / USA
s610adam / 2 boards / USA

 

[hochopeper]

Thanks, I’m in for 2 as well!


MaxReboBand / 2 boards / USA
as8912 / 2 boards / USA
ahtllc / 2 boards / USA
dBel84 / 2 boards / USA
Flamethrower1 /2 boards/ USA
Signal Lost / 2 boards / USA
diy.tiger / 2 boards / NZ
MShipmanPE/ 2 boards / USA
Angchuck / 2 boards / Singapore
Francois G / 2 boards / USA
Asuslover /2 boards /USA
Guerilla / 2 boards /Denmark
astromo / 2 boards / Australia
Kay Pirinha / 2 boards / Germany
pinkfloyd4ever/ 2 boards / USA
Sixto / 2 boards / USA
Tubesguy / 2 boards / USA
E_Fortier / 2 boards / Canada
Hicoco / 2 boards / France
Liva / 2 boards / Canada
Kokanee / 2 boards / Canada
chermann/ 2 boards / Austria
twocents/ 2 boards / USA
s610adam / 2 boards / USA
hochopeper/ 2 boards / Australia

 

[Dibya]

Hi Everyone,
Here is some PSU option,
Feel free to use your own design.

Another Psu Designed by Owner of Chipamp.com in Past:
(This was my first PSU)
Chipamp power supply – (mis) Adventures in Hi-Fi

BOM is under $30

Basic PSU:-
D1: KBPC3502 ( Select the package you want to use)
CX: https://www.mouser.com/ProductDetail/Panasonic/ECW-FE2J474KA/?qs=wYonFgBYHKkV/7JwdBfsaA==
CR: https://www.mouser.com/ProductDetai...EpiMZZMukHu%2BjC5l7YYQBV/jCy/7T3hj5t4%2BfqBA=
RC: https://www.mouser.in/ProductDetail/KOA-Speer/MO2CT631R222J/?qs=qJYTfuAnAfoxfBoTkFFvDw==
Choose Whether You like Proto Board or Point to Point
Bom is under $22 ,
Schematic: basicpsu — ImgBB

XRK971 CRC PSU:-
https://www.etsy.com/in-en/listing/820063565/all-cees-class-ab-psu?ref=shop_home_active_4

Emerald PSU: (Not for Commercial Use) [Its bit of a overkill]
C1 to C20: 2200uf 50v ( Any low ESR from good brand like Nichicon)
CXD: Panasonic ECW-FE2W474QA
Diode Capacitor : Panasonic ECW-FE2W474QA
D1 to D8 :Vishay VS-HFA08TB60-M3
As for resistors, Use KOA Metal Oxide one
Schematic: https://ibb.co/bQ37VWp

Gainclone PSU by MR.Carlos:
http://www.decdun.me.uk/gainclonesnub.html

 

[xrk971]

Well that was quick. We have 25 people for 50 boards. The Xmas amp giveaway is now closed. As soon as the PCBs arrive, I can build the verification builld (or unless Vunce beats me to it).

Then if all is good, I will collect payment for shipping in the Swap Meet Forum and then order the final 50 boards for shipment.

Thanks for your interest. If you change your mind, please let us know so someone else can use the boards.

Here is the list as it stands on Dec 27, 2020:

MaxReboBand / 2 boards / USA
as8912 / 2 boards / USA
ahtllc / 2 boards / USA
dBel84 / 2 boards / USA
Flamethrower1 /2 boards/ USA
Signal Lost / 2 boards / USA
diy.tiger / 2 boards / NZ
MShipmanPE/ 2 boards / USA
Angchuck / 2 boards / Singapore
Francois G / 2 boards / USA
Asuslover /2 boards /USA
Guerilla / 2 boards /Denmark
astromo / 2 boards / Australia
Kay Pirinha / 2 boards / Germany
pinkfloyd4ever/ 2 boards / USA
Sixto / 2 boards / USA
Tubesguy / 2 boards / USA
E_Fortier / 2 boards / Canada
Hicoco / 2 boards / France
Liva / 2 boards / Canada
Kokanee / 2 boards / Canada
chermann/ 2 boards / Austria
twocents/ 2 boards / USA
s610adam / 2 boards / USA
hochopeper/ 2 boards / Australia

 

[Francois G]

What a blast! Thank you X, and everyone involved.

I always wondered what a properly designed and implemented chipamp sounded
like. We shall find out!

Happy New Year and best wishes for 2021.

 

[Kay Pirinha]

As I get it, the sole reason of the supply voltage restriction to less than +/- 40 V are the LM317/337 voltage regulators. Are there any drawbacks if they were replaced by 15 V zeners and properly calculated resistors? They just feed the offset servo circuitry that isn't in the signal path?!?
Best regards!

 

[xrk971]

Hi Kay Pirinha,
I was thinking of the same thing myself. Probably 15v zeners and 4k7 1W resistors will give you about 11mA max at 50v. It’s a DC servo that’s not doing much so probably should work fine. Although we should check with Jhofland to see what he recommends for that opamp in terms of current.

 

[Kay Pirinha]

As in the worst case the TL071's output current calculates to 15V/215K||332K||332K = 0.16 mA, the total current draw is dominated by this opamp's idle current. I don't have it's value handy, but I guess that we should be on the safe side with your 11 mA .
Best regards!

 

[Vunce]

Man!! That was quick, nice job X and all involved.
Now, I wish my parts would arrive soon to build a board. Like so many others this holiday season, my parts have stalled somewhere between Texas and New York

 

[Kay Pirinha]

Hi xrk971,


I've redone some calculation: At +/-50 V and 15 V zeners, the current through 4k7 series resistors calculates to 7.5 mA. As the TL071's idle current draw is 1.4 mA, this should be ok anyway. A wattage of 0.5 W should suffice for these resistors.

Best regards!