Sound Quality Vs. Measurements

[ThorstenL]

Hi,

Originally Posted by a.wayne

OK some graphs looking at amplifiers, ones that knee buckles below 8 ohms and the ones that don't ...

Electrocompaniet, Goldmund, Plinus Class-a mode...

Alas, I do not see a SINGLE Amplifier in this quartett which precisely doubles it's output power from 8R to 4R for 0.1% THD.

So based on your evidence so far there is no Amp that "doubles down" under the conditions under which the Citation XX is specified.

Basically another case where the vendor with the honest specs gets beaten up over them while the BullS...t merchants are lauded as paragons of performance due to their less transparent specs...

I guess if HK had rated it at 250W8R/500W4R @ <0.5% THD (which they could likely have done) all would be well...

Ciao T

[ThorstenL]

Hi,

Originally Posted by bcarso

When Harvey Rubens and I sat in the audience at a local AES talk about grounding issues with pro equipment, the speaker started his talk with "Hi. I'm George P. Maggilicuddy*, and I have a Pin 1 Problem". Harvey and I spontaneously erupted:

HI GEORGE!!!

Not that many people in the audience found this amusing, whether because they were recovering alcoholics or just uninformed or possessed of a minimal sense of humor, we never knew.

George may have been Bill (Withlock).

Given that it's the AES (and who it's leading lights are) I though proof of a double humorectomy was required before they let you in? How did you two sneak in...

Ciao T

[a.wayne]

Yes, true , then there is 2 ohm ....

Look at the graphs again T, all 3 tell a different tale, the goldmund and the electro really fall apart after 8 ohms , unlike the plinus and I'm not surprised I found the Plinus the best sounding ...

anyway put a bid in on the XX...........

[ThorstenL]

Hi,

Originally Posted by tvrgeek

I am totally blank on what the H parameter charts are trying to tell me. When I see the Cob-Vcb chart, this is showing me the Early effect? What do I do with this?

All of this shows you how a devices parasitics change if voltage cross or current through the device change.

They allow you to derive the various parasitic resistance (early effect induced limited collector impedance, Beta changes, Changes of the internal emitter and base impedance as well as the parasitic capacitances), so they allow to tell you what goes wrong and where if you change voltages and/or currents (which you will as a transistor that works only static is not useful in an amplifier)...

Of course you can just blissfully ignore all the non-linear parasitics and throw a ton of looped feedback around the Amp instead...

Originally Posted by tvrgeek

Side note, The On-Semi datasheet for the 2N5401 is identical to the Motorola, right down to the defects in font.

That could be related to the fact that Motorola Semiconductors was spun off and is now called "On-Semi", just as Philips Semiconductors is now NXP and Hitatchi Semiconductors is now Renesas...

Ciao T

[ThorstenL]

Hi,

Originally Posted by a.wayne

Look at the graphs again T, all 3 tell a different tale, the goldmund and the electro really fall apart after 8 ohms , unlike the plinus and I'm not surprised I found the Plinus the best sounding ...

Your comments make me think you need a lot of power.

In this case the Plinius looks like it has the most distortion of all of them.

Maybe you just like distortion?

Ciao T

[a.wayne]

So distortion measurements matters ...........

[bcarso]

Originally Posted by ThorstenL

Hi,



George may have been Bill (Withlock).

Given that it's the AES (and who it's leading lights are) I though proof of a double humorectomy was required before they let you in? How did you two sneak in...

Ciao T

No, I know Bill. And this was no Bill

[bcarso]

Originally Posted by jcx

no, say it aint so...

at least don't try to support the criticism with "conventional engineering", Bode Sensitivy analysis, build dedicated hardware like Cordell...

Langford-Smith 4th ed., Supplement section at the end, following the index. 1952 and prior cites. Obviously not as detailed as Otala, but the gist is there about feedback going "wrong".

[ThorstenL]

Hi,

Originally Posted by a.wayne

So distortion measurements matters ...........

No, this was "on line audio discussion standard reply # 1" when someone posts they preferred a Tube (High Distortion) Amp over a Solid State (Low Distortion) Amp...

Ciao T

[godfrey]

Originally Posted by tvrgeek

I still don't know why someone would put two 4148's in parallel with a red led...

I've seen that in another circuit, with a footnote explaining that it's optional to use either the two diodes or the LED. Maybe that's the idea here too.