[Leonarfd]

Been using the Feliks Audio Echo since the pre launch price of 300euro, at times I want to upgrade but it still sounds really great. Also using the Beyerdynamic A 20 amp when I'm not using tubes, great synergy with Vérité.

 

[ziggz]

Been using the Feliks Audio Echo since the pre launch price of 300euro, at times I want to upgrade but it still sounds really great. Also using the Beyerdynamic A 20 amp when I'm not using tubes, great synergy with Vérité.

I’m using the Echo mkII and just slotted in these bad boys the other day, still burning them in, but damn good already.

https://www.tubemonger.com/Tungsram_MPs_1968_E88CC_Gray_Industrial_Serial_No_p/705.htm

 

[Leonarfd]

I’m using the Echo mkII and just slotted in these bad boys the other day, still burning them in, but damn good already.

https://www.tubemonger.com/Tungsram_MPs_1968_E88CC_Gray_Industrial_Serial_No_p/705.htm

Nice, had some great tubes I changed out but they became duds after some days. Learnt the stupid way of ordering on ebay, next time its going to be a verified store.

 

[goldwerger]

The funny thing about tubes is unless the amplifier is some totally busted design, rolling tubes does not actually alter the frequency response, the changes in FR are completely perceived, probably related to material changes, changes in stage output impedance, or alterations in distortion spectra.

But don't want to go to far down that path since we now have a thread for this type of thing lol.

@L0rdGwyn was really interested to learn more about your comment above in the Caldera thread that I’m moving here per your (implied) suggestion…

Getting your expert insight what actually changes when you swap tubes and why would probably be quite interesting to a few of us…

 

[gonintendo]

@L0rdGwyn was really interested to learn more about your comment above in the Caldera thread that I’m moving here per your (implied) suggestion…

Getting your expert insight what actually changes when you swap tubes and why would probably be quiet interesting to a few of us…

Yeah I was under the impression that output impedance actually does change FR on dynamic drivers

 

[ziggz]

@L0rdGwyn was really interested to learn more about your comment above in the Caldera thread that I’m moving here per your (implied) suggestion…

Getting your expert insight what actually changes when you swap tubes and why would probably be quiet interesting to a few of us…

Waiting patiently for the response as well

 

[PopZeus]

Since ZMF and Cayin seem to be thick as thieves these days, I'm curious to hear more about the new 805A's headphone out. Looks like it's primarily a speaker amp, but one would hope the 6.3mm jack would hold up to the rest of Cayin's head amp line.

 

[Pharmaboy]

Been using the Feliks Audio Echo since the pre launch price of 300euro, at times I want to upgrade but it still sounds really great. Also using the Beyerdynamic A 20 amp when I'm not using tubes, great synergy with Vérité.

Always thought this a lovely amp. Never had the chance to hear one, unfortunately...

 

[L0rdGwyn]

@L0rdGwyn was really interested to learn more about your comment above in the Caldera thread that I’m moving here per your (implied) suggestion…

Getting your expert insight what actually changes when you swap tubes and why would probably be quite interesting to a few of us…

Yeah I was under the impression that output impedance actually does change FR on dynamic drivers

Yes! This is true, depending on the driver in question. Sorry, I should have clarified but I didn't really want to get into it on that thread.

I think most people know that a headphones rated impedance is a nominal value, meaning the impedance is not constant across the frequency range, how flat the impedance curve is is dependent on the specific driver. With dynamic drivers, there can be resonances at low and high frequencies where the impedance will spike. Something called a voltage divider is formed between the output impedance of the amplifier and the impedance of the driver - essentially the output voltage of the amplifier is split across these two impedances, how much voltage is dropped across each will depend on the ratio of these impedances.

So, if the driver is being run by an amplifier with a relatively high output impedance, you may see a bump in the frequency response at these resonant frequencies as more voltage is being dropped across the driver due to the impedance spike at that frequency. If the output impedance of the amplifier is very low, then the impedance spike at these resonances becomes negligible in terms of frequency response since nearly all of the voltage will be dropped across the driver.

That's a pretty basic explanation without using math, but I hope it makes sense. There is tons and tons of info out there just on this subject if someone wanted to dive deeper into it.

So yes, that is one way tube rolling can affect the frequency response IF you are changing output tubes to different types that will significantly alter the output impedance of the amplifier. However, I don't think that explains a lot of the differences people hear when tube rolling, especially when swapping input tubes.

Often you will see people say "X tube is warm and Y tube is bright" even if the two tubes are the same model, say two different 12AU7 for example. If you were to measure the frequency response of the amplifier with these two tubes, you would most likely find it measures exactly the same with both! So why is there a perceived difference?

This is bit of a mystery, and I'm sorry but I don't have a definitive answer, but my suspicion is is related to the distortion characteristics of the tubes having a psychoacoustic effect. Since tubes are imperfect devices, if measured you will often see differences in THD between two tubes of the same type, even if they are both NOS measuring, which certainly is audible and will affect how someone perceives the sound.

Also, there may be some contribution from material and construction differences of the tubes. I think you'll find this isn't something that has been studied in any scientific way, but it seems to me there is enough anecdotal evidence to suggest plate / grid / cathode material and construction does contribute to the character of a tube's sound in a meaningful way.

But the point I was trying to make is that these differences truly are perceived, the amplifier's frequency response is not changing in any measurable way when you swap tubes of the same type!

 

[Pharmaboy]

This is bit of a mystery, and I'm sorry but I don't have a definitive answer, but my suspicion is is related to the distortion characteristics of the tubes having a psychoacoustic effect.

That's a pretty fine supposition--given your knowledge & those amazing amps, you're more likely to be right here than most.

I think this all circles back to the philosophical null point underlying so many audio discussions about devices that measure similarly but sound different: as good and evolved as measurements are, many of the characteristics that seem to matter in audio (and human perception of audio) are not measurable (yet).

 

[jonathan c]

And now a little detour into ‘the State of Solid’

[A serendipitous pairing: Flux Lab FA-22 and ZMF Atrium. Highly recommended.]

 

[goldwerger]

Yes! This is true, depending on the driver in question. Sorry, I should have clarified but I didn't really want to get into it on that thread.

I think most people know that a headphones rated impedance is a nominal value, meaning the impedance is not constant across the frequency range, how flat the impedance curve is is dependent on the specific driver. With dynamic drivers, there can be resonances at low and high frequencies where the impedance will spike. Something called a voltage divider is formed between the output impedance of the amplifier and the impedance of the driver - essentially the output voltage of the amplifier is split across these two impedances, how much voltage is dropped across each will depend on the ratio of these impedances.

So, if the driver is being run by an amplifier with a relatively high output impedance, you may see a bump in the frequency response at these resonant frequencies as more voltage is being dropped across the driver due to the impedance spike at that frequency. If the output impedance of the amplifier is very low, then the impedance spike at these resonances becomes negligible in terms of frequency response since nearly all of the voltage will be dropped across the driver.

That's a pretty basic explanation without using math, but I hope it makes sense. There is tons and tons of info out there just on this subject if someone wanted to dive deeper into it.

So yes, that is one way tube rolling can affect the frequency response IF you are changing output tubes to different types that will significantly alter the output impedance of the amplifier. However, I don't think that explains a lot of the differences people hear when tube rolling, especially when swapping input tubes.

Often you will see people say "X tube is warm and Y tube is bright" even if the two tubes are the same model, say two different 12AU7 for example. If you were to measure the frequency response of the amplifier with these two tubes, you would most likely find it measures exactly the same with both! So why is there a perceived difference?

This is bit of a mystery, and I'm sorry but I don't have a definitive answer, but my suspicion is is related to the distortion characteristics of the tubes having a psychoacoustic effect. Since tubes are imperfect devices, if measured you will often see differences in THD between two tubes of the same type, even if they are both NOS measuring, which certainly is audible and will affect how someone perceives the sound.

Also, there may be some contribution from material and construction differences of the tubes. I think you'll find this isn't something that has been studied in any scientific way, but it seems to me there is enough anecdotal evidence to suggest plate / grid / cathode material and construction does contribute to the character of a tube's sound in a meaningful way.

But the point I was trying to make is that these differences truly are perceived, the amplifier's frequency response is not changing in any measurable way when you swap tubes of the same type!

That is such a fanastic read - thanks for spending the time on such a detailed reply. Very informative and thought provoking. I'm certainly going to go down a couple of rabbit holes for more deeper reading on some of the topics you raised.

 

[Wes S]

The last time I heard and felt subbass like this was with my old pair of Ori's (a planar that can slam) and the Liquid Platinum hybrid tube amp w/ Raytheon 7730 tubes. Holy crap the VC's can dig deep and slam with this amp (Cayin HA300mk2) and these tubes (RFT 6SN7, Elrog ER300B, and Sicte/G.E. 22DE4)! The bass is so quick, impactful, deep and weighty it's startling at times, and it's very addictive listening to my favorite Electronica tracks.

 

[bigjako]

as good and evolved as measurements are, many of the characteristics that seem to matter in audio (and human perception of audio) are not measurable (yet).

I think you perfectly summarized the situation here, better than I’ve ever heard it said and better than I’ve ever been able to express personally. All the measureheads at ASMR are convinced that a single number like SINAD fully capture and value a given piece of equipment. But they’re measuring some arbitrary number simply because it CAN be measured, and many of them don’t even listen to the music. One day, maybe, we‘ll understand how to measure everything that we hear but today ain’t it.

Edit to say that half the stuff that makes this hobby so magical can barely be described consistently, let alone measured. The discussion around changes in what we hear by tube rolling being a prime example. Let’s let ASMR try to tell us what tube is the “best” and laugh at all the site bans that ensue.

 

[Pharmaboy]

Edit to say that half the stuff that makes this hobby so magical can barely be described consistently, let alone measured.

You got that right!

The myth of measurements is comforting...it offers believers the reassurance that their subjective experience of audio matters less than "the science." In this measurement paradigm, measurements are presumed to fully describe something--or come so close that there's little left to argue over. It measures well, so it must sound good.

If only life were that simple. I lived through an unforgettable measurement-myth failure: the "bits are bits/digital is perfect, forever" cult that took over the audio world in the early 1980s. Music studios were throwing out elaborate analogue systems and replacing them with digital. Cheap CD players were flooding the market & people threw out turntables and LPs.

Some audiophiles tested the claimed superiority of digital. I bought a solid, mid-price Philips CD player & had it modded by an wizard audio tech, which gave the sound more finesse & musical nuance than most players (ie, I didn't have to run screaming from the room when violins played on it). I already had many CDs & could easily compare the same recording on digital vs vinyl. Those comps were a bloodbath for digital. With the sole exception of deep bass, which digital conveyed more readily than vinyl (subs don't lie), everything else sounded vastly better, more musical & real on vinyl.

In audio circles, jitter was unknown then. CD players were not tested for jitter; nor was digital equipment in studios. Just a few years later, in the early '90s, everybody was talking about jitter and how it degraded digital sound. It totally mattered to sound quality whether the digital chain had significant jitter or not...but at first, nobody knew about jitter.

This clearly showed the hubris of audio engineers who promoted early digital products based on "perfect" measurements (when they actually sounded pretty bad). We can only measure something when we know it exists.

The irony of this lesson is we're always in the very same position, just a few years away from identifying an electrical/electronic characteristic that totally matters in audio, and learning how to measure it.