Low-distortion Audio-range Oscillator

Jump to Latest
#1,723
benb said:
Could this be why tube amps sound better, DC can't get through the output transformer? [/snark]
Click to expand...

No. A small dc offset on a loud speaker has absolutely no effect on the sound.
It does however add additional heating of the coil. As the coil heats it loses efficiency and this can have an effect on the sound. A large dc offset will either drive the coil into the plate folding the former in or drive it out of the gap. Either way you have damage to your speaker.

I can agree that tube amps sound different from solid state but it is only a matter of opinion
that tube amps sound better.

Incidentally,we had just as many fried speaker come in for repair from tube amps as SS.
 
Last edited:
#1,725
Anyone listen to music? A pretty good jam can be found which really exercises a system... deep, deep lows, transients, highs and great playing. Go to HD Tracks and down load "Freight Train Jam' by WAR from the album 'The World is a Ghetto'.

Enjoy! -Richard
 
Last edited:
#1,729
I was looking over the description of the oscillator manual of a K-H 4400A and it suddenly dawned on me that without the regenerative feedback, we could have a really flexible notch filter, cheap. The notch circuitry is built-in and selectable freq. Its the oscillator circuit itself without the regen feedback path. A disconnect switch for the regen path and an input port to the notch et al and I dont have to build anything. I spare 339A could be used for that. ?? Just an idea.

Thx-RNMrash
 
Last edited:
#1,730
The problems with the state variable filter used that way is the intrinsic distortion of the amplifiers and the tuning. That is the core of the analyzer in several analyzers, the Boonton and the Amber are two examples. The passive notch, like the B&K, are better. You could modify the B&K with active circuitry to make a tuneable high q notch with it. We just need to reverse engineer its circuitry, not a small task.
 
#1,731
davada said:
No. A small dc offset on a loud speaker has absolutely no effect on the sound.
Click to expand...

Actually it can. Cone drivers are not that linear and a small DC offset can move the voice coil enough to reduce/increase the distortion some. If you look at a Klippel plot you can see the source of the issue.

A small DC offset can saturate the transformer of a electrostatic speaker increasing the distortion a lot.
 
#1,732
1audio said:
The problems with the state variable filter used that way is the intrinsic distortion of the amplifiers and the tuning. That is the core of the analyzer in several analyzers, the Boonton and the Amber are two examples. The passive notch, like the B&K, are better. You could modify the B&K with active circuitry to make a tuneable high q notch with it. We just need to reverse engineer its circuitry, not a small task.
Click to expand...

It's that complex?
 
#1,733
1audio said:
Actually it can. Cone drivers are not that linear and a small DC offset can move the voice coil enough to reduce/increase the distortion some. If you look at a Klippel plot you can see the source of the issue.

A small DC offset can saturate the transformer of a electrostatic speaker increasing the distortion a lot.
Click to expand...

I meant smaller offset than that. Less than 1Vdc.

Electrostatics are another matter.
 
#1,735
The K-H 4400 has a very low-Q filter, with not much notch depth. Not a good candidate i my opinion. Most oscillators use relatively low-Q filters for tuning. The 339 and 239 probably have the highest Q filters, but even so their notch depth would not be much over 30dB. None of the commercial oscillators I've seen use a Twin-T for tuning -- most use a Wien or bridged-T -- inherently low-Q.
 
You must log in or register to reply here.
Top Bottom