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GB#2: Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD
GB#2: Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD
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Old 20th July 2020, 02:04 AM   #1
Destroyer OS is offline Destroyer OS  United States
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Join Date: Nov 2005
Location: PNW
GB#2: Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD
Default GB#2: Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD

Click the image to open in full size.
(Image of prototype)

The EC7293 uses 2 chip amps in parallel for high power with a discrete error correction frontend which reduces distortion; and has very low memory distortion. High sensitivity makes it perfect for a variety of sources with 8ohm and 4ohm speakers.

Input impedance: 27k
Gain: 32db
Distortion 1K; 8ohm; full power w/Antek AS-3225: <0.0005%
A short review.

At 8ohms:
Click the image to open in full size.

At 4ohms:
Click the image to open in full size.

Click the image to open in full size.

Board size: 6.25x2.25"

*****There is not a mirrored left/right set because it would screw up the feedback layout*****

Discrete front end: 4 transistors

PVI: The frontend uses a photovoltaic power supply for galvanic isolation of the signal path. It uses a G4 LED bulb with a current source to disable the onboard driver of the G4.

Distortion: <0.0005%

High power: These are running in "modular" mode so that they can handle a 4 ohm load with some dips, while providing substantial power with a max output current of 20A. The Antek AS-3225 is a great fit for 60/120w. More power may be possible if you follow the guidelines of the TDA7293 datasheet and make provisions with higher voltage capacitors, and larger heatsinks.

Terminals: Happy to say we've found some that are based on a copper metallurgy, that accept decent sized wire, and don't strip too easily (I can torque them pretty good with screwdriver) that the boards are made to fit, and I recommend in the BOM.

Input Capacitor
: This one is less sensitive to capacitors compared to the DIY7297. It has provisions for the same PHE426 and other caps. There is a slot-hole next to the pads so you can zip tie on larger caps and it has extra pads on the bottom to connect off board/long input capacitors.

CFC, smart PCB layout, & Copper Pours: Trace routing is optimized to improve performance and the power capacitors are placed for field cancellation (CFC); and copper pours are used for lower inductance.


Click the image to open in full size.

Dualpole PSU PCB

Board Size: 4.25x3"

TO220 Diodes

CFC, smart PCB layout, & Copper Pours

Via holes for snap caps

RC and bypass: dampen the transformer & reduce noise


Suggested implementation with EC7293:
  • 18000uF to 24000uF per rail
  • Antek AS-3225 transformer
  • Keratherm insulators from DIYAudio store. (Chip tabs are 1.1” apart).
  • Heatsinks need to be larger than used on the 7297, nearly any enclosure with heatsinks for sides should work
  • 3U enclosure from DIYAudio store is a good fit. **
  • 2x Duapole's for dual mono with 2x transformers (Antek AS-2225)

**2U may work in dual mono with two smaller (shorter) transformers

Price & Amount needed to Print:

In order to print these up so I don't run out the day after, I'd like to see 12x pairs to get this going. To anyone that liked the DIY7297, this one is better, simply better.

EC7293+G4LEDR PCB $45ea (you'll need 2, to make a stereo amp)
DualPole PSU PCB $40ea

Shipping USA $8
Shipping International $16

And it will come with a BOM and some build details.

Quote:
DeeJayBump 2,2
SAinet 2,2
shacketf 2,2
myl 2,2
mctavish 2,2
Stephen S. 2,2
jameshillj 2,0
drkingweeb 2,2
HaflerDh500Fan 2,2
genjamon 2,2
angchuck 4,1

Last edited by Destroyer OS; 11th August 2020 at 05:53 AM.
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Old 20th July 2020, 03:27 AM   #2
DeeJayBump is offline DeeJayBump  United States
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Join Date: Aug 2006
GB#2: Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD
I'll have a stereo set [1x DUalPole PSU PCB + 2x EC7293 PCBs] Thanks.
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Old 20th July 2020, 06:06 AM   #3
SAinet is offline SAinet
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Join Date: May 2018
Please put me on the list for dual mono
2x DUalPole PSU PCB + 2x EC7293 PCBs
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Old 20th July 2020, 06:26 AM   #4
asuslover is offline asuslover  Romania
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Join Date: Aug 2016
I would like to know how much the components from your suggested BOM will cost , so I will have an idea about the total cost of this amp,
Thanks
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Old 20th July 2020, 07:04 AM   #5
shacketf is offline shacketf
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Join Date: Jul 2020
Please put me on the list for dual mono
2x DUalPole PSU PCB
2x EC7293 PCBs
International shipping
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Old 20th July 2020, 11:27 AM   #6
myl is online now myl
diyAudio Member
 
Join Date: Mar 2015
GB#2: Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD
Please count me :
2x DUalPole PSU PCB
2x EC7293 PCBs
International shipping
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Old 20th July 2020, 12:22 PM   #7
mctavish is offline mctavish  Austria
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Join Date: Feb 2008
Location: Niedersterreich
Please put me down also for a pair of EC 7293 pcbs, and a pair of power supply pcbs for a dual mono setup.

Thanks for doing this 2nd GB!!
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Old 20th July 2020, 04:51 PM   #8
Destroyer OS is offline Destroyer OS  United States
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Join Date: Nov 2005
Location: PNW
GB#2: Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD
Quote:
Originally Posted by asuslover View Post
I would like to know how much the components from your suggested BOM will cost , so I will have an idea about the total cost of this amp,
Thanks
Parts to populate both amp boards is about $130 + $8 hardware + $10 LEDs + $10 pvi cells. Each PSU board is $38~ to populate. Then add in your choice of input capacitor, enclosure, wire, and connectors.

I think this post would give you an idea of what a beautiful build would could come out to. One can spend less going with 1 transformer and 1 PSU ($100 min less not including shipping). You can use different chassis parts, different wire.
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Old 20th July 2020, 08:22 PM   #9
DeeJayBump is offline DeeJayBump  United States
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Join Date: Aug 2006
GB#2: Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD
Jeremy, please add a 2nd DualPole PSU pcb to mine, thanks.
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Old 21st July 2020, 09:49 AM   #10
angchuck is offline angchuck  United States
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Join Date: Dec 2005
Location: Silly'pore
Please include me

I know I keep bothering ya.

One stereo set and one psu to Singapore.
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