diyAudio

diyAudio (https://www.diyaudio.com/forums/index.php)
-   Group Buys (https://www.diyaudio.com/forums/group-buys/)
-   -   Folsom EC7293: PVI Powered Frontend, 60/120w 8/4ohm (https://www.diyaudio.com/forums/group-buys/338275-folsom-ec7293-pvi-powered-frontend-60-120w-8-4ohm.html)

Destroyer OS 23rd May 2019 07:17 PM

Folsom EC7293: PVI Powered Frontend Amplifier, 60/120w 8/4ohm, 0.0005% THD
 
**Updated: Lower distortion with a slightly different board.

Alright everyone! We’ve got the redesign done.

https://i.ibb.co/ZGbPwMy/EC7293-glow.jpg
(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%

At 8ohms:
https://i.ibb.co/WVs2Bn2/EC7293-THD-8ohm-2.png

At 4ohms:
https://i.ibb.co/9tm4dDw/EC7293-THD-4ohm.png

https://i.ibb.co/MNgh3G1/EC7293-Amp-GB-PREVIEW-1.png

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.


https://i.ibb.co/71Fb5Sg/dualpoleppv.png

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 need a commitment of 12x, two EC7293 boards and one PSU board. I'm hoping to see a lot more than 12x. 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:

Paul Hirst 2,1 (1x)
s610adam 2,2 (1x)
Pi DE 2,1 (1x)
Roundtoit 2,1 (1x)
pistollero 2,2 (1x)
jmc207 2,1 (1x)
Danny23 2,2 (1x)
Domino99 2,1 (1x)
annamarykahn 2,1 (1x)

Paul Hirst 23rd May 2019 07:35 PM

Put me down for one please and thank you!

Paul

s610adam 23rd May 2019 07:46 PM

Hey I'm interested in a dual mono setup to try

flavo cadillac 23rd May 2019 10:45 PM

What's the time frame for the boards to be ready?

Destroyer OS 23rd May 2019 11:06 PM

Once the GB goes through 2-3 weeks is normal for printing.

danielwritesbac 24th May 2019 06:42 PM

Oh my gosh! The documentation quality is so much better.
But, you really could have bragged up the output linearity instead of understating it.
Per each channel, four made-for-audio output fets in addition to an EC circuit!
Sure has clear and evident means-to-work.

Also, it is at fairly big scale, but if you wanted to know when you have enough, this will do it.

Roundtoit 24th May 2019 06:50 PM

Paul Hirst 2,1 (1x)
s610adam 2,2 (1x)
Pi DE 4,2 (2x)
Roundtoit 2,1 (1x)

Destroyer OS 24th May 2019 06:58 PM

Quote:

Originally Posted by danielwritesbac (https://www.diyaudio.com/forums/group-buys/338275-folsom-ec7293-pvi-powered-frontend-60-120w-8-4ohm-post5801121.html#post5801121)
Oh my gosh! The documentation quality is so much better.
But, you really could have bragged up the output linearity instead of understating it.
Per each channel, four made-for-audio output fets in addition to an EC circuit!
Sure has clear and evident means-to-work.

Also, it is at fairly big scale, but if you wanted to know when you have enough, this will do it.

Well, I was trying not to use so much hyperbole this time... But it's true, it's a very good amplifier. I think people under estimate the value of memory distortion as well. The transistors are BC550's. I consider them to be extra special and near magical compared to other transistors I've used for things like phono.

I updated the graph to the 8ohm, I accidentally put up 4ohm. This one isn't as hard to read, either.

pistollero 25th May 2019 07:55 AM

Paul Hirst 2,1 (1x)

s610adam 2,2 (1x)

Pi DE 4,2 (2x)

Roundtoit 2,1 (1x)

Pistollero 2,2 (1x)

jmc207 26th May 2019 05:59 AM

Paul Hirst 2,1 (1x)

s610adam 2,2 (1x)

Pi DE 4,2 (2x)

Roundtoit 2,1 (1x)

Pistollero 2,2 (1x)

jmc207 2,1 (1x)


All times are GMT. The time now is 01:52 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 17.65%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio

Wiki