Valves have microphony full stop the end...

[Solypsa]

Circuit design involves an approach that plays to benefits and not faults. All components feature both.

The thread title is not a question, rather a statement. It is of course true.

Does this mean that no serious audio engineer should design circuits with valves? Funny...

 

[analogsa]

I've heard the APL Hifi DSD-MR tube hybrid dac many times & it is dead quiet and utterly natural sounding. So I think it depends on the circuit design and price point you're talking about.

No, it does not depend on circuit design or price point. This thread is about the applicability of dhts in phono stages. Which is very distant to dacs. The issues are twofold. The obvious one is the voltage levels, which in a phono stage are easily 3 orders of magnitude smaller than those inside a dac. The second is the directly heated part, which sadly, exacerbates issues like microphony and hum. A DHT phono stage is a nearly impossible feat to pull and many designers will never dare attempt it. Is it worth it? That is the real question.

 

[jeff1225]

First of all, that would be "Your" not "You're"; then, "taping" should be "tapping" - that aside, I do realize it can be hard to understand what the tapping experiment conveys. As to that "simple" question of yours, you can probably guess what I think of it. Enjoy the weekend.

If I remember correctly, you are the person that puts tin foil all over his equipment and calls it an upgrade. Tin foil upgrades and tapping on equipment, I guess I'm just not in tune with that corner of the hobby.

But as always, thank you for the entertainment.

 

[jeff1225]

I wanted to reply to ACK's rude answer myself but then I didn't have a good internet connection while on holidays. And now after reading his reaction to your posting, I'm glad I didn't waste time or data roaming for that person. Just not worth it

What's sad is I was asking him a legitimate question. From what I understand he's a typical keyboard warrior, and is polite and docile in person. I guess some people are still learning how to act on social media/forums.

 

[Loheswaran]

Circuit design involves an approach that plays to benefits and not faults. All components feature both.

The thread title is not a question, rather a statement. It is of course true.

Does this mean that no serious audio engineer should design circuits with valves? Funny...

Can I just say that I wrote the headline to get people talking. When I read the body of the text I kind of realised that I don't think I communicated what I had intended to.

So let me write that first of all I hadn't intended to be antagonistic. I was genuinely seeking to discuss and in part pose the question that I have long pondered since that solid state designer in question said this about valves.

How does it affect a system - is it a ringing? a feedback? what? If there is a feedback loop in the audio chain then I can get how it simply cannot be benign. Likewise if damper rings just don't work where does it leave us?

All said and done - if it so fundamentally flawed, how is it that so many respected buyers and designers both use valves and manage the issue?

I've been using solid state for a while, but I must say that I was beguiled with a very simple single ended amp I once borrowed for a month.

I'm not big into CD, but needed a CD player, and got one with a valve output stage and must say it sounds pretty good.

I'm going through an audio epiphany in the last year or two and have moved more and more towards more body, warmth and romance - maybe valves is the next step

 

[cjfrbw]

Too many minds of more ponderous grey matter than mine have struggled with these questions for too many years without satisfactory conclusions, except to say that the differences are not out of our realm of perception for some ineluctable reason.

I am satisfied with not knowing the 'why' of some things, just the apparent results.

I have my own objectivist limits, but tubes, and in particular directly heated triodes, do indeed do things that solid state can't quite manage, and I luv some of my solid state, like the VFETs.

I would be satisfied if the VFETs were all I had, but the DHT triodes open up doors of perception that I value and would miss. I can't believe that it is JUST about particular harmonic distortions, maybe the electrons perform in a flame and vacuum in a way that the brain can interpret and appreciate.

 

[DaveC]

If there is a feedback loop in the audio chain then I can get how it simply cannot be benign. Likewise if damper rings just don't work where does it leave us?

I think there are a broad range of things that get added to the music via all sorts of things, all the parts in the system have an effect. There is no way around it, you can say you are all for a system that adds nothing to the recording but I don't think it's possible to achieve IRL, and thus nobody has experienced it. It's a theoretical abstraction.

Of the general categories of things that get added to the recording, one of them I'd label "psychoacoustically correct". Meaning what's added matches up with what the brain expects to hear. In the case of tubes and the feedback they add, I believe it is psychoacoustically correct and mimics both spatial information we expect to hear as well as timbre, so it adds a sense of "space" and makes vocals and instruments sound more realistic.

Tubes don't achieve what they achieve because they are some super-accurate ultra-precise zero-distortion piece of gear.

 

[Alrainbow]

We need the definition of microphony ? All in Audio are ! while tubes are an obvious pic it's all of our devices. Has anyone ever put a dummy load on an amp ?

 

[ack]

If I remember correctly, you are the person that puts tin foil all over his equipment and calls it an upgrade. Tin foil upgrades and tapping on equipment, I guess I'm just not in tune with that corner of the hobby.

But as always, thank you for the entertainment.

It's copper foil and mumetal, and capacitors and transistors and diodes and inductors, etc - and I suggest you stop the foolish posts and questions.

 

[jeff1225]

It's copper foil and mumetal, and capacitors and transistors and diodes and inductors, etc - and I suggest you stop the foolish posts and questions.

I hear you're very nice in person. Maybe one day you'll learn that your online presence carries over to the physical world.

 

[bazelio]

Microphony is usually manageable. IMO, when you buy tubes from reputable sources like Brent Jessee, you pay for insurance such as tubes low in microphony. Vibration management for tube phono chassis's is not a bad idea, on top of it. And, it'd be silly to design a phono stage around a DHT tube family that is particularly sensitive. But then, it'd also be silly to design for 80 dB of silent solid state phono stage gain and then prefer doing the laundry to listening to music. A good trade-off is 25-30 dB of SUT gain in front of ~40 dB of tube gain, and no hum at normal volume from the listening chair. Design for less, and folding socks might become appealing.

 

[Alrainbow]

Does this designer consider the acoustic feedback , mechanical feedback to the tubes ?

 

[Stacore]

That said nothing changes microphony - damper rings don't entirely either

Dear Loheswaran,

It's a bit like saying nothing changes bumps on a road, so let's not use cars. Well, smart people invented suspensions

Cheers,

PS Solid state does react to vibrations as well

 

[Alrainbow]

Exactly my point in fact of someone were to alter the frame of an amp or footers etc it effects the sound. Owning a LAMPI dac has led me on many a journey on tubes and there effects to our sound
Some tubes mesh for an example are not quit as much as solid plates. Also mesh I feel are more effected by EMI and RFI too. There are so many ways to vary and if done well improve the sound.
How or why some feel tubes are the largest cause of Induced noise confuses me.

 

[assessor43]

for all their supposed flaws, a...I need to put on another record....

 

[microstrip]

We need the definition of microphony ? All in Audio are ! while tubes are an obvious pic it's all of our devices. Has anyone ever put a dummy load on an amp ?

Microphony is one of the most interesting subjects in high-end. In order to analyze and discuss it we must separate microphony due to the electric signals flowing in the device and microphony due to acoustic feedback from the speakers or other mechanical sources of noise.

Differences between tubes can usually be associated to different transfer curves (even between tubes of same manufacture), parameters such noise in all the bandwidth, not just in the audio band and surely microphony.

Tube microphony was deeply studied in the 40's and 50's - tubes were subjected to all kind of vibrations and the output signals were analyzed. I remember seeing references in old Navy tube manuals to these tests, but as they predated internet, looking for them will be very time consuming. Although each case is a different case we can expect DHT to be more sensitive to microphony than indirect heated tubes - the very thin cathode filament wires should be more susceptible to microphony than the heavier cathode plates.

 

[Alrainbow]

Great post microstrip. Even tubes near EMI above , below or sides has ill effects. I use a ps audio power plant P10. It was on a top 5 feet above my tube device took a a few hours to realize it was causing the hum. I did the usual methods to fix it and they helped but not stop it. Just moving out from the shelves stopped it. Also had an issue with a router transmitting WiFi too. 4 feet away not good enough. Unplugged it stopped it. I make posts to not stack but we all do to some degree. My phono pre has a separate psu it needs to be two feet away from phono premap and pre amp

 

[analogsa]

Interesting, but why is electro magnetic interference discussed in the same thread? Valves do often suffer from severe electromechanical issues, but as far as EMI goes they are generally less sensitive than SS devices.

 

[Alrainbow]

Why it's part of microphonics it's why I said let's define it. If you ask me any noise a tube adds that's not just circuit distortion is this topic

Correct me if I'm wrong I'll not be upset lol.

 

[analogsa]

More often than not such sensitivity is due to proudly displayed preamp valves, so it is more of a design issue, than being inherent to the valves themselves. A phono stage with visible valves just cannot be a good idea and even in a line stage this design feature is a bit adventurous. A careful design can deal successfully with induced hum, while microhonics are always an issue.
DHTs are the most problematic with induced hum as well. Too bad they also offer the best sound.