Amp too good for DIYaudio.

[Koifarm]

This amp was banned by DIYaudio without reason. It has 0.000033% THD at 1Watt/8ohm.

First shared working version is the T-rex 2d. It has about 75watt rms output and 0.000058% THD.

Schematic

Attached are gerber files to order the pcb yourself and ltspice sim files.

The second version is max 200Watt with even better THD = 0.000033 %

The third version I am testing at this moment it will output 400Watt. PCB I will publish soon after testing.

Ronny

 

[carbidetooth]

It was banned? Meaning one can't post about it? You're the designer? I must admit to being way too curious.

 

[Koifarm]

Yes, I designed it with some help of diyaudio members. But there are some sponsors there who became threaten by my designs and comments. So they banned and removed only some really good designs of me. I think this amp is really good.
I have also hypex ncore500 and purifi 1et400a amps with several input buffers(tube and/or opamp). Playing on dynaudio audience 122 and diy dynaudio active 4way. And I like the T-rex best, but that is subjective.

On this dutch forum you find also a build description. https://zelfbouwaudio.nl/forum/viewtopic.php?t=32419

 

[mlloyd1]

What is the frequency range and level for the quoted distortion figures and are these measurements on prototypes or simulation results?

 

[Chrispy]

Have not seen the arguments for/against. THD is just one aspect.

ps Were you banned, or the actual amp and either way, what are the specifics?

 

[JSmith]

banned by DIYaudio without reason.

Must have been a while ago yeah? Your profile there says;

Joined 2005-08-28 9:40 pm
Last seen 2023-12-02 12:28 pm
2023-12-02 12:28 pm
2023-12-02 12:28 pm

https://www.diyaudio.com/community/members/koifarm.36252/

I'm sure your design and free sharing of same will be welcome here.


JSmith

 

[pderousse]

"Banned" is the modern way of saying it is cool, so why is it actually cool?

 

[LTig]

In both designs the output stage has no protection against short cuts, or a low load pulling more current than the output transistors can safely handle. Is this intentional?

 

[JSmith]

The output stage has no protection against short

True, if the speaker terminals short, the amp’s only protection is PSU fuse. Without any current limiting, the output transistors can get pushed past their safe limits... which makes the design pretty risky. Also, I don’t see any DC protection in this design either? ...have to think about the safety of connected speakers.


JSmith

 

[Koifarm]

@mlloyd1 - It was measured with Cosmos E1DA dac/adc, range 20 to 20khz. 1Watt at 8ohm(2.83Vrms).

@JSmith - My last Alias was “ Monstercore”, I was banned because I post some comments about another banned member “Koifarm”. Koifarm is/was my inspiration and we live in the same village. Only this amp design was complete deleted.

@LTig - The schematics are only the amps as showed. This is because the most DIYselfers have a favorite power supply topology.
I ad just a few fuses in the power supply lines. The output fets are very robust.

@JSmith - The same about DC protection. If you want to use it you can use a ready made PCB or build it yourself.

If you get the Idea to build a great amp at low cost, build this one. Ad your preferred power supply and DC protection and then focus on source and loudspeakers. Enjoy the music.

 

[LTig]

The schematics are only the amps as showed. This is because the most DIYselfers have a favorite power supply topology.
I ad just a few fuses in the power supply lines.

That's a recipe for disaster. If only one fuse blows the DC of the other supply might kill the woofer in the speaker.

The output fets are very robust.

Fets do not suffer from thermal runaway, but they are not safe against too much current. There is a reason why data sheets list absolute maximum ratings for voltage and current.

If you get the Idea to build a great amp at low cost, build this one. Ad your preferred power supply and DC protection and then focus on source and loudspeakers. Enjoy the music.

Well, I had my share of power amps blowing up, don't need this anymore. OTOH I'm all in for active powered speakers so nothing to worry about any longer.

 

[Everett T]

That's a recipe for disaster. If only one fuse blows the DC of the other supply might kill the woofer in the speaker.

That's the first thing I thought, speaker killer.

 

[Koifarm]

Ltig, After 50years of amp building I never blew an outputstage and/or speakers. So for me there is no problem. And everyone who can build this amp can choose his preferred safety options. I am only publish the amp part because this topology with an opamp does the error correction works great. When using opa1655 or opa1611 on dip adapter you can even do better THD results. I also tried the OPA627 and that one works also great.
Everett T, feel free to ad DC protection. You can buy this for 5 euro on Amazon or Ali.

As on the photo I use SMPS( Connection or Hypex) with overcurrent protection.
Hypex has also an DC protection input, you need to ad a DC detection circuit.
I can publish that with the 400watt version.

 

[wwenze]

True, if the speaker terminals short, the amp’s only protection is PSU fuse. Without any current limiting, the output transistors can get pushed past their safe limits... which makes the design pretty risky. Also, I don’t see any DC protection in this design either? ...have to think about the safety of connected speakers.


JSmith

 

[LTig]

Ltig, After 50years of amp building I never blew an outputstage and/or speakers. So for me there is no problem.

Lucky you. I once killed a power amp by adding a TRS connector to its outputs to directly feed a 600 Ohm Headphone with low sensitivity. I was unaware that while plugging in the headphone its TRS connector creates a short cut for a few ms . That was enough to kill the driver chip and the output transistors of both power amps.

Not related here, but in another case a Naim power amp fed my speakers with a high frequency scream, which would have killed the tweeters if they weren't protected by fuses.

So things may happen, if not to you then to other people.

And everyone who can build this amp can choose his preferred safety options.

Agreed, but you should tell so when showing your design.

 

[Petrushka]

It was banned? Meaning one can't post about it? You're the designer? I must admit to being way too curious.

I think the part about “no reason” is wrong.

 

[Chr1]

Does the addition of the aforementioned protection circuitry to amplifiers affect the sound quality in any way?

If not, what is the reason for not including it in a design?

Thanks.

 

[Koifarm]

Adding an relais contact from the DC protection between amp output and speaker terminals should not influence the sound.
Further you can use this relais contact to suppress On and Off switching sounds.

There is a special component for all this, upc1237.

 

[Koifarm]

I think the part about “no reason” is wrong.

The reason was not told to me.

 

[PristineSound]

Why not send a sample to @amirm to be measured and tested?