Simple Symetrical Amplifier

[sofianirawan]

Mr.shaan, lc. ssa amplifier can be set klass a, anything that changed? i want to assemble the amplifier ssa in setting klass a. I own the following mr.nafiri assemble pleasant sound amplifier ssa ears, and sounded good and clear ... I myself also feel happy after hearing the sound the sound of the amplifier ssa

[shaan]

Originally Posted by sofianirawan

Mr.shaan, lc. ssa amplifier can be set klass a, anything that changed? i want to assemble the amplifier ssa in setting klass a. I own the following mr.nafiri assemble pleasant sound amplifier ssa ears, and sounded good and clear ... I myself also feel happy after hearing the sound the sound of the amplifier ssa

hi sofianirawan.

Of course the ssa can be class-a by placing more diodes in series with the existing biasing diodes. But I personally doubt there will be any sonic difference or reduction of THD.

Congrats on your SSA build.

[Esperado]

Originally Posted by shaan

Of course the ssa can be class-a by placing more diodes in series with the existing biasing diodes. But I personally doubt there will be any sonic difference or reduction of THD.

Class A is better to keep a listening room warm atmosphere.
(Why the hell this class A audiophile legend ?)

[Salas]

Tutorial on the Design and Characterization of Class-B and AB Amplifiers - YouTube

[shaan]

Originally Posted by Esperado

Class A is better to keep a listening room warm atmosphere.

Don't say. A pair of DOZ can give a mighty 15kelvin boost in room temp in 1 hour. Perfect room heater in a christmas night.

Why the hell this class A audiophile legend ?

Coz those audiophile x-spurts couldn't find a way to minimize the crossover distortion other than sinfully using lots of unholy negative feedback which is destined to "suck the soul out of the music". Poor kids... if only they didn't assume the feedback signal cycles inside the input stage... alas.

No matter, they've got train-loads of bucks so they can solve the problem the global-warming way.

[PauloPT]

Hi!

Remember some posts ago I posted a spice simulation that didn't look too good?
Turns out I had a problem with the LTSpice directive. Now I got it right and the distortion spectrum at 20kHz is attached bellow. Looks much better!
THD @ 20kHz @ 22V is about 0.02%.

I also had reported an oscillation problem. Gate resistors + input snubber (20pF // 3.3K as recomended by Keantoken) + 680pF input filter cap + a new, shorter, shielded, decent input cable, and the oscillations are completly gone! It's obvious to me now the culprit was that stupid inductive long cable. Gave the cable to the cat. He's having lots of fun with it! The amp is rock stable!

This little amplifier has the most beautifull extended highs I have ever listen to, an envolving midrange and unbelievable strong bass! Thank you Lazy Cat, Shaan and all ther others who worked together to design this wonderfull piece of art! Thank you, thank you, a billion thanks!

[PauloPT]

Another thing: huge soundstage!

Hi Shaan,

Could you please post the pcb layout in jpeg format or in a pdf with the drawing at the begining of the page?

Thank you.

[keantoken]

The 3.3k is in series with the 20pF, and this goes between the input and ground. You put them in parallel?

No amp should have problems with an inductive source impedance; all sources are inductive. But many of them do. I would provide the optimal input compensation network but I don't know which specific version you're using.

[PauloPT]

Sorry, no I meant to say 20pf in series with 3.3k.

The cable was really bad. I believe it was the main culprit. With a short shielded cable connecting the DVD player to the amp there's no oscillation I can perceive in the AM radio and the sound is amazing. I need yet to figure out how I'm going to connect the computer audio out to the amplifier, they're not that close.

I'm using Shaan version of the SSA.

[keantoken]

If the cable is short and there is minimal inductance to react, it should work fine, and can sound great. For a designer though, oscillation with long cables is a liability that should be corrected.

The problem could be your source. I think you should try a buffer between your computer and cable. Soundcard outputs may have several hundred ohms output impedance. A strange idea that popped into my head is using 300 ohm RF ribbon cable inside grounded metal conduit, but that's just strange.