Who can explain this FFT graph to me

[Gerrit Boers]

It also has a finger error, too many zeroes too soon. -60db = 0.1%, -80db = 0.01%
-100db = 0.001%.

Oops, my mistake.

unfortunately I won't be able to measure it again.

If it's not to much trouble for you to come to Maastricht, I'll be happy to measure all I can for you.

 

[Bas Horneman]

If it's not to much trouble for you to come to Maastricht, I'll be happy to measure all I can for you.

Hi Gerrit,

That is very generous of you! And I might just take you up on your offer. Because I'm very curious what my latest changes are going to measure like. At the moment I'm doing the changes (tonight the 2nd unit) and then the listening starts. Hopefully the listening will be positive.

 

[kevinkr]

One other comment Bas, and that is to make sure with no signal present that the plate voltage on your EL84 is at least 180V - 200V, which implies at the current I was suggesting that the raw supply be in the range of 400V minimum on the other side of that 12K plate resistor. (You could also change it to 10K, but I wouldn't go lower due the loss in gain.)

Fortunately you do have headroom in the supply to get the voltages you need.

 

[jacco vermeulen]

Bassie,

if you like to get a better grip on even and odd(un-even) harmonics, google for "massa-veer systemen"

(or get a degree in sea spectra-vessel vibration/acoustics)

 

[Bas Horneman]

Hi Jacco,

I've just read the whole wikipedia on the subject and I'm still clueless.

 

[Bas Horneman]

and that is to make sure with no signal present that the plate voltage on your EL84 is at least 180V - 200V,

Check. Got it to 215 last night.

 

[jacco vermeulen]

wikipedia

Makes me wonder sometimes how many Spicers can do a fast Fourier transform by hand.

 

[QSerraTico_Tico]

Spontaneous Vibrations

Bassie,

if you like to get a better grip on even and odd(un-even) harmonics, google for "massa-veer systemen"

(or get a degree in sea spectra-vessel vibration/acoustics)

You mean spontaneous vibrations Jacko?