Amp topologies and their effects on sound

If you were still planning it, they've released the 3.0 version of the S.E.X. now: http://bottlehead.com/product/single-ended-experimenters-kit-3-for-headphones-sensitive-speakers/

 

Oh no, Ken Rockwell managed to bring his overexposed oranges to tube amps!

 

Thanks @Armaegis, I had been watching developments on that since last year, on their forum. As I mentioned in another thread, I have discovered member @tomchr's Neurochrome projects which will allow me to build both an example of tube SET (Novar Spud) and an extremely low distortion SS chip amp (Modulus-86) for about the same budget as the S.E.X. I then hope to experience these two extreme points of view for myself.

Preparation: For the past 2 weeks I have been recalibrating my brain with new HD-600's (never heard them before). I must say I feared for the worst (veil and all that) but am so far pleasantly impressed. I have a large music collection to listen through.

 

You should try the Senns through @tomchr 's HP-1; it's a fantastic pairing.

 

Heh, one thing at a time Switching from the Ultrasone Pro-750's was interesting, but not an epiphany. At the moment I'm happy with my homemade low distortion op-amp based amplifier. It's been fine tuned by ear and oscilloscope over 3 or 4 years. I can only speculate how much better the HP-1 would be with the attention to detail that @tomchr has put into that.

On the other hand, my old faithful speaker amplifier is a Musical Fidelity B1 (by Tim de Paravicini) which is old-school SS with a healthy dose of THD and high output impedance so that it has "bloom" and "warmth". This brings me back on-topic and to my quest to answer that very question.

 

Using an oscilloscope puts you ahead of most DIYers right out of the gate. Unfortunately, it's rather difficult (read: impossible) to tell THD below a few percent on an oscilloscope. It will certainly help you avoid the major pitfalls, but to really drive the distortion down, assuming that's your goal, or at least get a handle on the THD, you need a distortion analyzer. Thankfully, a good (preferably external) sound card and some software will get you really, really far.

Some things to check out if you're looking for an inexpensive audio analyzer:
Pete Millett's sound card interface: http://pmillett.com/ATEST.htm
TrueRTA software: https://trueaudio.com/rta_abt1.htm
Or combine the sound card, interface, and software in this handy box: http://www.quantasylum.com/content/Products/QA401.aspx

Tom

 

I'm not using the oscilloscope to measure THD. More for basic troubleshooting and voltage and noise checks (with a low noise instrumentation amplifier). To check THD I use ARTA software with a 24-bit USB A-to-D. It was enough to see the bad crossover distortion on my class AB speaker amplifier (and enough to show me I could move it around but not really eliminate it with biasing changes).

 

This is good point about the op-amp also being tuned by ear...

As I have noticed with my op-amp rolling of an O2amp,
that there were oddities which were not in traditional sense of sound parameters,

But oddities in the perception of the ambient setting.
Ambient background and perception of place of Recorded live musical performances I was familiar with sounded odd or not same type place.
Like looking thru a variable warped window.

So I realized design around op-amp is important than just rolling,
And abandoned the op-amp route before I entered a can of worms I not have time currently to learn about.

I bought a small tube amp instead,
Since I am more familiar with those parameters, like tube type and biasing.