Get back to the topic. The topic is not each other, it's tubes.
As there's no truth in audio, making assumptions based on a graphic does not say much.
So, what's the info in post #15?
- does it show the SE at clipping level ?
- what's the story about masking of higher uneven harmonics ?
- is this harmonic content identical for all SE tube amps ? Many of us try keeping harmonics (esp. 2H) down by cancellation through driver choice.
- What about the effects of feedback on the harmonic content?
So, what's the info in post #15?
- does it show the SE at clipping level ?
- what's the story about masking of higher uneven harmonics ?
- is this harmonic content identical for all SE tube amps ? Many of us try keeping harmonics (esp. 2H) down by cancellation through driver choice.
- What about the effects of feedback on the harmonic content?
disco, I'll simplify things for you.
See below.
The difference is subtle but it's there.
That's incorrect. Try SET amp vs PP amp.
If you understand what to look at and have experiences with how they correlate to audible sound, you wouldn't be saying that.
The fact that you had to ask about this confirms what I suspected.
See below.
Post #10 and click on this --> Tube sound - Wikipedia, the free encyclopedia
The difference is subtle but it's there.
Thank you, clear.
Why I object against the name "tube sound" is because it suggests a relation between the principal components of an amplifier (being tubes) and the existance of an audiable distortion. It's possible (and a goal to many) to make neutral sounding tube amplifiers. So, the term "tube sound" might be appropriate for your (grand-) fathers AM radio receiver suffering from limited bandwith, power sag, intermodulation distortion and the lot but is a degrading name for someones work of merit.
A graphic reproduction of distortion figures is worthless without information about the conditions under which they were derived as it would be open for several readings. Personally I want 3H down to at least 50-60dB and higher uneven possibly to -100 dB. If that would take 18 dB of global feedback and an extra voltage amplifier, so be it. On the other hand (listening for irregularties) on a 4W SE I can tolerate for a -35 dB 2H at clipping levels. No problem as it would come up once every many minutes on my 98 dB loudspeakers. Not as problematic as a too slow slew rate or blocking coupling capacitors.
Why I object against the name "tube sound" is because it suggests a relation between the principal components of an amplifier (being tubes) and the existance of an audiable distortion. It's possible (and a goal to many) to make neutral sounding tube amplifiers. So, the term "tube sound" might be appropriate for your (grand-) fathers AM radio receiver suffering from limited bandwith, power sag, intermodulation distortion and the lot but is a degrading name for someones work of merit.
A graphic reproduction of distortion figures is worthless without information about the conditions under which they were derived as it would be open for several readings. Personally I want 3H down to at least 50-60dB and higher uneven possibly to -100 dB. If that would take 18 dB of global feedback and an extra voltage amplifier, so be it. On the other hand (listening for irregularties) on a 4W SE I can tolerate for a -35 dB 2H at clipping levels. No problem as it would come up once every many minutes on my 98 dB loudspeakers. Not as problematic as a too slow slew rate or blocking coupling capacitors.
SET and PP amp have audible sound characteristics due to no feedback vs feedback design.
Please reread post #15. They were all 1 W output.
I wasn't talking about someone's personal preference.
I was talking about SET amp. It's doesn't use "global feedback".If that would take 18 dB of global feedback and an extra voltage amplifier, so be it. On the other hand (listening for irregularties) on a 4W SE I can tolerate for a -35 dB 2H at clipping levels. No problem as it would come up once every many minutes on my 98 dB loudspeakers. Not as problematic as a too slow slew rate or blocking coupling capacitors.
Hi, just a quick reply to clear up the air.
Wish you had stated the power output in your post, ruling out that the smallest amp was at clipping level for instance... you're familiar with the fact distortion relates to output power I presume.
I've built since 2002 over two dozen power and pre amplifiers with tubes, from OTL SE to PP. Among them are four SE with overall voltage feedback, I'm sure I'm not the only one here.
To my experience (I've built four EL84 PP, one 6L6 and two KT88 PP) the trade off for PP is in the phase splitter suffering from tube aging and other nasty things happening at higher levels. But heh, I'm not a pro -feeding my tube babies through candy laces- but who is?
Wish you had stated the power output in your post, ruling out that the smallest amp was at clipping level for instance... you're familiar with the fact distortion relates to output power I presume.
I've built since 2002 over two dozen power and pre amplifiers with tubes, from OTL SE to PP. Among them are four SE with overall voltage feedback, I'm sure I'm not the only one here.
To my experience (I've built four EL84 PP, one 6L6 and two KT88 PP) the trade off for PP is in the phase splitter suffering from tube aging and other nasty things happening at higher levels. But heh, I'm not a pro -feeding my tube babies through candy laces- but who is?
If you are familiar with amp measurements and their sound, this much explanation from me wouldn't have been needed.
Now that bunch of things have been clarified for you, would you rephrase your statement about "no tube sound"?
Hi ja2dhc, with those solid Spice talents you might consider simulating the pre-amp feeding your amp. It's possible the even harmonics are cancelling out across part of the operating range. See here:
http://www.diyaudio.com/forums/tubes-valves/99125-cancelling-harmonics-2.html#post1172271
Adding 'tube sound' to the front end could actually be reducing it at the speaker terminals.
How did you get the nice THD chart, I also posted a question at ???????????????????????????????Q&A
hope you can answer my question.
Jaz
No wonder it looks good! It must have been quite a bit of work to capture all that data and plot them... Anyway, if you are ever in Shanghai, please let me know, we can meet up.
Jaz
I have discovered the Web which describes THD curve and be able to
download EXCEL MACRO as follows (sorry written in Japanese).
˜c—¦“Á�«ƒOƒ‰ƒt‚ð•`‚¢‚Ă݂悤
http://park21.wakwak.com/~eyp/jk1eyp/amp/measure/hizumi/pic/distortiongraph.xls
download EXCEL MACRO as follows (sorry written in Japanese).
˜c—¦“Á�«ƒOƒ‰ƒt‚ð•`‚¢‚Ă݂悤
http://park21.wakwak.com/~eyp/jk1eyp/amp/measure/hizumi/pic/distortiongraph.xls
Ayumi answered my question on his BBS, so I can try running the program in R. I will also check out the software link that you provided, it looks good for making actual test and measurement, so will complement pctube's calculated results.
Jaz
Last edited:
I built something like this before, but not like that.
I built my tube pre stage B+ 250V then class D stages 3.3Vdc (V analog) and another separate 3.3V (V digital) and then my power @12V
analog and digital grounds on my class D chip isolated.
I don't think your gonna get good results with a single power supply.
I also think your B+ on the pre is too low to really capture the tube's "personality". IMHO.
Also the support parts and their construction directly effect the pre. Just because it "simulates" means it works like that with low quality or certain types of parts (like carbon comp vs. metal film, vs. non-inductive wirewound. ect. or electrolytic vs. poly vs. PFTE vs PIO caps...ect)
I built my tube pre stage B+ 250V then class D stages 3.3Vdc (V analog) and another separate 3.3V (V digital) and then my power @12V
analog and digital grounds on my class D chip isolated.
I don't think your gonna get good results with a single power supply.
I also think your B+ on the pre is too low to really capture the tube's "personality". IMHO.
Also the support parts and their construction directly effect the pre. Just because it "simulates" means it works like that with low quality or certain types of parts (like carbon comp vs. metal film, vs. non-inductive wirewound. ect. or electrolytic vs. poly vs. PFTE vs PIO caps...ect)
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.