Diy audio popular amps simulations

[wahab]

Here a first little round of THD sims involving more or less popular
audio amps that are often displayed at DIY audio...

As first guests, the DX and Blame ES as well as 0stripper s AX2...

[lineup]

Thanks, wahab.
About those pics ... I kinda knew it.

[wahab]

Hi, Linup..

I retain Ostripper s design as base design for
future comparisons.

The Blame ES is not that bad, and is enough
for most speakers considering its 50W rating.

The DX should be definitively abandonned, as
it s lacking compared to the two others...

[wahab]

Next is an old design that is still well alive, i.e, Leach amp,
is compared to the winner of the first round..
Surprinsingly, despite its age, the old guy
is still relatively good.

The sims are made using modern devices, as
this allow valuable comparisons.

[ostripper]

I see you have started the thread. Total THD is not as important as it's content and how much of it occurs dependant on frequency.

In my tests , I check total THD at 200 , 1k , 10k , and 20k. The AX you mentioned has the lowest between 1k and 20k but rises when you test above 20k or below 1k. Other amps such as the symasym or apt (balanced single ended) have higher totals but are lower down to 100 or below and my GX will stay at .005% all the way to 40khz.

The DX by Carlos is a higher distortion unit , but sounds nice for a beginning DIY project. You add a CCS to it , you get lower distortion but lose sonics. It is what it is.

The fully complimentary amps like the leach almost fully cancel out the even order harmonic so you better have low or almost non-existent H3/5/7.

The reason to develop my own amp is to go modular so I can truly do side by side comparisons of all the major topologies in the real world.
Edit , one more point to make , simulate these voltage stages into a 2R load at higher power levels , simulating a "droopy" OPS , some will do much better than others.

OS

[wahab]

That s the turn of Pass F5 and John Linsley Hood 10W...

The venerable 40+ years old JLH10W has no problem
battling Nelson s iteration of the Profet..

[wahab]

Originally Posted by ostripper

.

Total THD is not as important as it's content and how much of it occurs dependant on frequency.

. The AX you mentioned has the lowest between 1k and 20k but rises when you test above 20k or below 1k. Other amps such as the symasym or apt (balanced single ended) have higher totals but are lower down to 100 or below and my GX will stay at .005% all the way to 40khz.

The DX by Carlos is a higher distortion unit , but sounds nice for a beginning DIY project. You add a CCS to it , you get lower distortion but lose sonics. It is what it is.

The fully complimentary amps like the leach almost fully cancel out the even order harmonic so you better have low or almost non-existent H3/5/7.

The reason to develop my own amp is to go modular so I can truly do side by side comparisons of all the major topologies in the real world.
OS

Hi, Ostripper

THD content is important, true, provided the THD is high
enough to be heard...

Although i prefer your recent design, that i also simulated, and
that will be displayed later, your AX still appeared as having
the best complexity/perfs ratio , so i elected to use it as timely
reference design for my sims..

The DX amp, well....i won t talk about it...

The fully symetrical amps have the advantage of
more balanced perfs, although they are more difficult
to master in matter of THD at low and medium frequencies
where the single differentials siblings are really hard to
beat considering their relative simplicity..

As to design your own amps, that s great , since you manage
to have fairly good results..
I m far from being as prolific as you , at least in the building
area..

w

[wahab]

Originally Posted by ostripper

Edit , one more point to make , simulate these voltage stages into a 2R load at higher power levels , simulating a "droopy" OPS , some will do much better than others.

OS

This wouldn t be a fair comparison, since some designs
use more than one power bjt pair, but at the same time,
using only one power devices pair for about 50W RMS/8R
is just not serious...

[ostripper]

My second point in the last post is best illustrated below in the attachment.
The AX , while I will build it and it is proven .. a VERY good amp , will not do anywhere as well into a 2R load , standard single pair OP -EF2. It is will degrade substantially at the H7 and 9.
OS

[lineup]

Not many amplifiers are built to do well at 2 Ohm.
So, no big thing AX is not for low ohm speakers.
For such we need to start parallel output devices, as you say.

I parallel sometimes just to lower distortion at hi-power out.
There are several benefits from parallelling.