2stageEF high performance class AB power amp / 200W8R / 400W4R

[Kay Pirinha]

Tony, I'm scratching my head about how to solder the e'lytics after the power transistor legs?

Anyway, If it were mine, I wouldn't bother with protruding pins.

Best regards and a happy new year to all!

 

[astx]

Prepare transistors legs, insert into pcb. mount it on heatsink. screw the transistors without thermal pads. cut the transistor pins. remove screws , transistors. insert and solder lytics. insert transistors into pcb, mount it on heatsink, carefully solder the transistors with a small/long solder iron.

HNY2024

 

[HRDSTL]

Heureka, first setup okay, seems to have worked without error.

DC (+20V, -20V) Current consumption: 53mA
DC offset: 50mV

I'm happy...

 

[astx]

Offset will go to zero if finally speaker output ground is connected to input ground on the starground. You can try this adding a wire in your test setup from input groun to output stage ground.

 

[HRDSTL]

Today I finally got around to actually running SA2014 and hooked up the speaker. I'm satisfied with the sound overall, the SA2014 was only connected to a smartphone and a DC 43V power supply. I am waiting for the 600W toroids from toroidy.pl to arrive so I can complete the bias and start work on the second channel.

No bumps in the speaker when turned on or off.
Have a nice Saturday

 

[HRDSTL]

The first 600W transformer from toroidy.pl at home (240V, 2x50V). First channel finally done, bias set to 21.3 mV, supply voltage at idle 69.2V, DC offset 4mV. Hopefully in March I'll get to finish the second channel. I'd like to have SA2014 in the box finished by the end of the year!

 

[HRDSTL]

Tony,
I have a question! I am now also choosing a preamplifier for the SA2014 and I want it to be from discret parts (no operational amplifiers) and at the same time not too complicated. So far the Sapphire from RJM seems to be a good candidate. Since I want to set it to Class A, how much input sensitivity does the SA2014 have at full power?

If I calculate correctly it comes out to about 1.3V

 

[astx]

Gain is 31.37 = ((8200/270)+1)
For 220W 8R at RMS 42.6 V
Need 1.36V RMS at input.

 

[Ujang Ojil]

Hello @astx I don't really understand this part

 

[astx]

This is a 8 pin placeholder for a VI limiter if one want's this.
Have fun, Toni

 

[HRDSTL]

Friends, as time went by I finally managed to complete all the blocks for SA2014. I have everything set up and ready to put in the modushop 5U box. I'm going on vacation in August so I won't be able to do much, but I still need to save up for FURUTECH cinches and massive terminals.

I'm currently finishing the Gainwire MK3 preamplifier from @dadod , the panels are in production and I'm also working on the DCG3 headphone amplifier from @Salas . If everything goes according to plan I should be able to finish all three preamp, headamp and amplifier by the end of the year.

• SA2014
• PSU
• 2x 600W toroids
• inteligent softstart (inc. DC protect)
• SSR speaker protect

 

[astx]

This is THE 10th anniversary build! Gratulation!
My SA2014 - 4 Channel version is now playing since nearly 10 years every day minimum 4-6 hours...
... 15000-20000h for the lytics. Still no troubles. Just use high quality parts and keep it cool...
Have fun, cheers to all SA20xx builders!

 

[bloqhed]

Friends, as time went by I finally managed to complete all the blocks for SA2014. I have everything set up and ready to put in the modushop 5U box. I'm going on vacation in August so I won't be able to do much, but I still need to save up for FURUTECH cinches and massive terminals.

I'm currently finishing the Gainwire MK3 preamplifier from @dadod , the panels are in production and I'm also working on the DCG3 headphone amplifier from @Salas . If everything goes according to plan I should be able to finish all three preamp, headamp and amplifier by the end of the year.

• SA2014
• PSU
• 2x 600W toroids
• inteligent softstart (inc. DC protect)
• SSR speaker protect

Looks fantastic! Could you direct me towards the softstart boards if possible?

 

[astx]

The SA 2014 original housekeeping/softstart controller is project "D" - see post #1

 

[inyashd]

Dear Toni Sir,
IXTH80N20L is Littelfuse & IXTH48P20P IXYS
Available any issue in use SA2021-NCH - New Class H.

 

[astx]

Both parts are now Littelfuse with IXYS technology. Littelfuse has aquired IXYS some years ago.
The parts are available at e.g. Mouser or Digikey.
You need matched triples to avoid current imbalance and thermal runnaway.

Have fun, Toni

 

[astx]

Single slope current limiter for SA2021-NCH - New Class H

 

[HRDSTL]

Hi tony,
I'm about to finish SA2014, I'm working on the front and back panel design. Tomorrow I send it to production.

But I have a question about the SA2015, ...if it could be used as a dual mono heladphone amplifier? What is the minimum supply voltage to use to be used as a HP amplifier? I have Denon AH-D7200 headphone and I'm still looking for an amplifier of sufficient quality for them with which I'll be aurally satisfied. So far the best I've heard was GainWire MK3 from dadod, but I want to try SA2015 as well. With a quiescent current of 250mA the amplifier would still be in class A, which I also like. I forgot to mention headphone have an impedance of 25 ohms.

I use as DAC/Preamp from SMSL MDA RAW 1 😉

Thanks Tony ☕

 

[astx]

SA2015 has a gain of about 30dB.
A headphone amp typically has 6 - 12dB gain. Have you had a look at the SA2022 preamps headphone amp?