What motivates you to build more amplifiers?

[IamJF]

I have made some speaker measurements above 20KHz. The reviews of Class D amplifiers measure ultrasonic noise of hundreds of millivolts. That is comparable to the signal for low volume listening. I do not want my ears to be the low-pass filter.

I started a new thread over there with some measurements. It's not fitting here but it's an interesting topic to have a closer look!
https://www.diyaudio.com/community/threads/ultrasonic-noise-with-class-d.392655/#post-7185248
I hope you join!
Do you have any sources/links for Class D with such strong HF noise? Hundreds mV ... that's really bad!

Back to topic.
I did some power amps. First started cause of not enough money for a high end amp (did a design similar to THEL audio with FET output - pretty nice). Later cause of the need of special features (like DC coupling) or just parts lying around (big transformer and some caps ... so I bought a few TDAs and made a nice circuit board ;-)).
But as you already wrote - after all it's not cheaper as buying comercial designs and so I'm normally modifying amps when I have some special needs for a project (like insane S/N with DC coupling).
And since Hypex NCore I don't think into doing a design by myself any more - I can't reach these specs with a normal design. The only amp I know in the same ballpark (and actually 2-3dB better in noise) is the AHB2 from Benchmark - which is actually a design I WOULD be interested in 🤓 (cause it performs incredibly and sounds flawless).

 

[Indigent Audio]

I don’t care about cost but to say diy is not cheaper is a bit of a misnomer. It is true with an a/b or class d cost is often a wash but the cost of class A amps on the retail market is very high.

 

[EdGr]

I don’t care about cost but to say diy is not cheaper is a bit of a misnomer. It is true with an a/b or class d cost is often a wash but the cost of class A amps on the retail market is very high.

I was comparing apples to oranges. DIY cost is higher than mass-market hi-fi because one is buying good components in tiny quantities. However, one is building high-end equipment.
Ed

 

[YashN]

This reminds me that new topologies are also a good motivation, provided performance is increased over existing ones. Class D for instance, I can see is taking up although there are many mentions of noise for early implementations, but I know next-to-nothing about it yet. It is intriguing to me and thus warrants some experiments with.

 

[sser2]

Saving money isn't really a motivator for this hobby. In fact I would say it's more expensive than buying gear. Buying parts at retail, NOS tubes, sockets, costly mistakes, re-do's, then there is chassis fabrication where one might be motivated to buy a table saw, drill press, more tools, maybe even a CNC machine. Then there is wood, aluminum, nuts and bolts. Then there is the need to stock parts capacitors, resistors, misfits, regulators, wire lots of wire, solder, and biggies like output transformers, power transformers, chokes, etc. Then there is the need to set up your bench maybe with a few oscilloscopes from eBay, Fluke meters, signal generator, distortion measuring, maybe software to do detailed analysis, bench power supplies, then an array of hand tools for electronics.

For me I could have bought a few top end 300B amps by now! For the investment in the hobby is that big financially. But some people buy a boat or an RV or an airplane for their hobby, or elaborate wood shops. Cost saving is always touted as a reason for DIY, but I have not found that to be true! 😉

I've never seen a commercial tube amplifier that cannot be substantially improved. All of them, even the most expensive, are compromised, sometimes in many different ways.