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Do you like tube distortion? - listening test
Do you like tube distortion? - listening test
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View Poll Results: Which of the files you prefer by listening?
I prefer ella1 but I do not have an ABX result 7 53.85%
I prefer ella2 but I do not have an ABX result 5 38.46%
I prefer ella1 and I do have an ABX result 1 7.69%
I prefer ella2 and I do have an ABX result 0 0%
Voters: 13. You may not vote on this poll

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Old 8th November 2018, 10:48 AM   #41
maty tinman is offline maty tinman  Spain
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The key is something of coloration and not too much like usually tubes amps make.

A clean SET preamp (tube or SS) with this H2 predominance and clean/very clean SS I think must be the "holy grail" to enjoy very good recordings at home. Better with great SNR off course.

Clean: low/very low distorsion.
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Old 8th November 2018, 02:42 PM   #42
gabdx is offline gabdx  Canada
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I observed on some speaker vs resistor load that my 6bl7 tube amp which is triode and low feedback has a 0.7 db gain at 50hz vs 100 and 1000 hz.

However this amplifier has a poor frequency response -3db at 8khz but it is very enjoyable.

6bl7 triode with almost 4 db of feedback is not a lot in push pull, however the THD is very low!

The repeated impulse at -3db shows at 2V peak-peak a 20us rise time and 69us fall time.
This means that in theory 11khz is the true cut off point.
This response is bad under 0.5 watts and gets better over 2 watts because transformer losses I believe.

I don't think it has anything to do with THD since the listening levels are typically low.

This makes me realize a lot of things for tube amplifiers especially.

Since the bigger transformers have usually more loss and coercion their bandwidth is especially limited for very low signals such as 0.2 watts but improves as the power is augmented because the loss becomes more averaged.

Getting a small output transformer would actually be the best solution for low feedback amplifiers.

If you add feedback the feedback will restore the bandwidth.

I can easily boost the feedback to 10 db in my 6bl7 amp and restore the high frequency response.

There is absolutely no ringing or any artifacts on the scope.

We really need to come up with something better than spectrogram and thd figures to gauge the quality of the amplifiers....

What we need is an amp that can control a difficult load at low power (0.5watt) with flat response, and multiple signals without any ringing and as low IMD as possible and THD.
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Old 8th November 2018, 03:12 PM   #43
PMA is offline PMA  Europe
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If you are calling for rise time measurement, it is the easiest thing to measure and it is about 1us for this circuit, which reflects in >300kHz -3dB corner. Everything seen in time domain has its image in frequency domain. However, non-linear distortion is not easy to see in the scope screen, unless you use a notch filter. IMO everything is well known and there is no need to "investigate" some different methods.
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Old 8th November 2018, 03:51 PM   #44
traderbam is offline traderbam  Europe
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Pavel,
Have you done a control experiment where you compare the original wav file to the recorded file you made with a "straight wire" to see if you can tell a difference?
I ask because this would inform the sensitivity of your test.
IOW the sampling/ADC process has to be of sufficient accuracy to allow a certain amount of wav file difference to be distinguishable.
Brian
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Old 8th November 2018, 04:32 PM   #45
gpapag is online now gpapag  Greece
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Do you like tube distortion? - listening test
Pavel thank you for posting the measurements.

George
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Old 8th November 2018, 04:45 PM   #46
gabdx is offline gabdx  Canada
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Quote:
Originally Posted by PMA View Post
If you are calling for rise time measurement, it is the easiest thing to measure and it is about 1us for this circuit, which reflects in >300kHz -3dB corner. Everything seen in time domain has its image in frequency domain. However, non-linear distortion is not easy to see in the scope screen, unless you use a notch filter. IMO everything is well known and there is no need to "investigate" some different methods.
I see more like 3.5us , and what was the frequency for the square wave or was it only a rise time test?

Can you do the same test with 10000hz square wave with 95% duty time at only 2v peak-peak into a speaker or resistor?
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Old 8th November 2018, 08:10 PM   #47
PMA is offline PMA  Europe
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Quote:
Originally Posted by traderbam View Post
Pavel,
Have you done a control experiment where you compare the original wav file to the recorded file you made with a "straight wire" to see if you can tell a difference?
I ask because this would inform the sensitivity of your test.
IOW the sampling/ADC process has to be of sufficient accuracy to allow a certain amount of wav file difference to be distinguishable.
Brian
Yes of course. Since some time, I always do it. I was NOT able to tell the difference in a DBT. However, I am not going to post original file at the moment, as it always invokes sighted impressions. It may happen, if there will be participants interested, that after the poll expiration I may prepare 3 files: original, wire and tube. I need then all of them to have exactly same size. The equal size is one of the reasons I post wire x tube and not original x tube. People would take any measures to guess which is which.
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Old 8th November 2018, 08:17 PM   #48
PMA is offline PMA  Europe
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Quote:
Originally Posted by gabdx View Post
I see more like 3.5us , and what was the frequency for the square wave or was it only a rise time test?

Can you do the same test with 10000hz square wave with 95% duty time at only 2v peak-peak into a speaker or resistor?
No, rise time is defined as the time between 10% and 90% of the total step swing level. We need to keep standard definitions and we need to have some basic knowledge to lead such discussion. BW is then 0.35/Tr and it fits quite perfectly.

10kHz square or single step makes absolutely no difference in Tr (10%-90%). It (rise time) is always the same. And I cannot load a link preamplifier stage with a speaker. This is a task for the power amplifier, I hope you understand the difference.

I am sorry but we need to keep some knowledge level. I am not going to debate the elementary definitions and principles, as it would start a never ending circle of off topic questions.
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Old 9th November 2018, 02:44 AM   #49
gabdx is offline gabdx  Canada
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I apologize, this is not my profession, but a very serious fun hobby.

I thought the raise time was from a power amplifier. Sorry.
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Old 9th November 2018, 06:40 AM   #50
ivanlukic is offline ivanlukic  Serbia
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Ella1 has much higher high frequency distortion, especially from brass section, and is unpleasant to hear. I noticed the difference in a couple of seconds. I first heard ella1 and than ella2. It was not necessary to wait till brass section from ella2 started to blast, I noticed the difference from the first seconds of ella2. And all that from the crappy miniature loudspeaker on my Lenovo notebook!
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