driving your power stage

[nhuwar]

Is it a horrible thing to drive you power tube's with solid state.

Nick

 

[SY]

If so, I'm doing a horrible thing. So is tubelab, who uses a very similar approach.

 

[nhuwar]

Cool I wanted to make sure I won't get kicked out of the forum if I did
I was thinking about using an TI amp chip to run each channel
the only thing Is it has a 4 ohm out so I would have to use a output transformer in reverse.

Now would that raise eyebrows?

Nick

 

[Wavebourn]

It idepends on what kind of solid state device you use.

 

[nhuwar]

TPA0172PWP Is what I was going to use.

Nick

 

[Wavebourn]

TPA0172PWP Is what I was going to use.

Nick

It will work. The tube will amplify this amp's distortions and add own coloration.

This approach is used in some homebrew AM transmitters to drive plate modulators, when solid state power amp drives output toobs through inverted P-P output transformer.

 

[nhuwar]

At max power 20khz it only produces 1%thd thats well bellow the audible range of humans 15%thd.

I didnt think that was to bad but if it wolud make the amp noisy I'll look for something else.

Nick

 

[Bandersnatch]

At max power 20khz it only produces 1%thd thats well bellow the audible range of humans 15%thd.

I didnt think that was to bad but if it wolud make the amp noisy I'll look for something else.

Nick

Hey-Hey!!!,
I doubt your numbers. Especially with no description of the spectral content. There will be a distinct difference in the audibility threshold depending on odd v. even, and what the decay with increasing order looks like.

I beleive you could probably pick out 1% if it were either all first even( 2nd harmonic ), or all third harmonic.
cheers,
Douglas

 

[Brian Beck]

Is it a horrible thing to drive you power tube's with solid state.

Yes, despicable.

 

[Wavebourn]

At max power 20khz it only produces 1%thd thats well bellow the audible range of humans 15%thd.

It depends on spector of distortions. Some distortions are well audible way below 1 percent.

 

[SY]

Yes, despicable.

Them's fightin' words, Beck!

 

[Geek]

I've seen really good designs that use a MOSFET source-follower to drive the output stage from a high impedance tube gain stage, so I'd say it's not a bad idea, just a little heresy

 

[nhuwar]

Bandersnatch Thats the one tricky thing. As Humans can alter what we perceive Ie "preconceived notion" You alter what you hear to be what you think you are hearing but your actually not hearing it.

And I now You and some other people will disagree but I'm going by statistics.

Also yes I have no rock soulid proof of that , it could be wrong but it also could be the mean of the detectable thd by the human ear.

But please dont think I'm telling you you are wrong because this is not quantitative data just my 2 cents.



Nick

 

[Bandersnatch]

hey Nick,
No need to take back or water down your disagreement. It is a discussion, not a bar fight...

Look at a sine wave with varying harmonics of a set amount of THD. This will give you some idea of its audibility I think. The odd stuff looks a lot worse than the even.
cheers,
Douglas

 

[nhuwar]

I agree 100% with you there bandersnatch deffinently why GOD gave man oscilloscope.
Can I get an amen Hallelujah praise the lord for good test equipment!!

 

[Bandersnatch]

I agree 100% with you there bandersnatch deffinently why GOD gave man oscilloscope.
Can I get an amen Hallelujah praise the lord for good test equipment!!

Don't forget the brains to analyze what the test equipment shows us. Else it would just be called magic and that would be the end of it( except for the Church comming after us that is ).
cheers,
Douglas

 

[Brian Beck]

Them's fightin' words, Beck!

Tongue planted firmly in cheek...

In fact, I am currently marveling at how well an OPA637 opamp can communicate music in a headphone amp. Of course, when I switch back to my 7119-based headphone amp, I'll go "Ahh, now that's even better!".

 

[nhuwar]

I always wanted to make a regulator around the attached circuit.

There would be 2 of one to raise aqnd one to lower just throw a dc gear motor on a variac.
I would have the each circuit switch a relay but one spins the motor cw and the other ccw.

Dont realy know if it would work but the circuit is so cheap to build who cares.

 

[nhuwar]

You know I put that in the wrong place.
It's supposed be in power supply design under power conditioner.

OOps

 

[rdf]

I agree 100% with you there bandersnatch deffinently why GOD gave man ......

24-bit soundcards and RightMark!