Thoughts on tubed preamps?

[majingotan]

The comment was about whether the stereotypical tube distortion characteristics were euphonic or not.

My experience tells me you can't put science behind it as it lies within subjectivity or preference. Like what @ SIY mentioned, even different tube amp topology differ from the way they sound. I mentioned that overly bloomy sound (aka mellow and laid back from SIY's post) is not euphonic to my subjective preferences. Heck it sounds like I'm listening to a lower quality speaker at that point. At least with Saga preamp, it has not leaned towards bright but the vocals are slightly more forward while sounding a tiny bit thicker. The sound stage is widened a tiny bit so there are some upper mids that are a tiny bit more diffused compared to passive. The key words for me is "a tiny bit". That's what makes it euphonic to me. It's splitting hair difference at least with the Saga preamp. Different topologies will have more extreme versions of what SIY mentioned.

 

[watchnerd]

Serious question: what are they? I've designed/built/worked on a lot of tube amps and preamps over the years and never saw anything consistent in their distortion or overload characteristics.

Likewise, I've heard people say that tube amps are bright and forward and others say that they're mellow and laid back.

I expected you to chime in as soon as I said that.

Yes, I know and you know there is really no such thing as tube sound because it depends on the topology.

I would also note that DSP plugins for DAWs also have an opinion on what tube sound is.

But clearly the OP has something in mind when he started the thread.

Perhaps ask him?

 

[watchnerd]

My experience tells me you can't put science behind it as it lies within subjectivity or preference. Like what @ SIY mentioned, even different tube amp topology differ from the way they sound. I mentioned that overly bloomy sound (aka mellow and laid back from SIY's post) is not euphonic to my subjective preferences. Heck it sounds like I'm listening to a lower quality speaker at that point. At least with Saga preamp, it has not leaned towards bright but the vocals are slightly more forward while sounding a tiny bit thicker. The sound stage is widened a tiny bit so there are some upper mids that are a tiny bit more diffused compared to passive. The key words for me is "a tiny bit". That's what makes it euphonic to me. It's splitting hair difference at least with the Saga preamp. Different topologies will have more extreme versions of what SIY mentioned.

Yes, it's all subjective and dependent on the topology. I don't think anybody is saying otherwise.

We also know that people have a belief of what tubes sound like in consumer electronics.

We also know that tube simulation DSP plugins for DAWs have an opinion on what tubes sound like or how they should be simulated.

We also know that, on the instrument side, tubes are used as effects boxes in things like guitar and bass amps. My own is an example.

"Tube sound" (in common audiophile meaning) != sound you get from everything made with tubes

You guys know this. And you know it's at least 50% marketing, 50% intentional design decisions. But you also know what people are commonly referring to when they ask, so it's kind of silly for us to get into a semantics discussion every time.

If the goal is to fight against the use of "tube sound" to mean something in particular (usually a gentle compression, soft clipping, etc.), amongst audio enthusiasts, good luck with that quest....

 

[majingotan]

"Tube sound" (in common audiophile meaning) != sound you get from everything made with tubes

In the light of this, I would agree that "tube sound" is considered sound produced by an effect box which is also loosely defined as the term effect is broad in itself. Measurements see it as "distortion" but clearly different topologies create different type/level of distortions and even with similar distortion plots between two different tube topologies, the sound coming out of them cannot be simplified by having DSP plugins since even those DSP plugins have their own specific sound effect that is different from other tube topologies despite distortion plots being very close to each other

 

[RayDunzl]

Audio Buddy had an Audible Illusions pre for a few years.

He now prefers direct from DAC to amp.

 

[watchnerd]

Audio Buddy had an Audible Illusions pre for a few years.

He now prefers direct from DAC to amp.

Is the DAC "tubey"?

 

[RayDunzl]

Is the DAC "tubey"?

It could sport a label designating No user serviceable thermionic emitters inside.

 

[SIY]

Yes, it's all subjective and dependent on the topology.

More than just topology or tube choice or whatever. It's about engineering. If you say, "cathode follower using an ECC88," I can design that to be absolutely transparent with distortion levels in the 0.00x% range and the ability to maintain flat response when driving a cable and downstream devices OR I can "design" that device to have terrible distortion performance and a frequency response that droops when a cable and load are attached to it.

Neither of which, of course, has anything to do with whether there's a tube used. And the latter choice represents maybe half the cheap eBay tube "buffers," with the other half being "opamp, with the tube being essentially non-functional."

If the goal is to fight against the use of "tube sound" to mean something in particular (usually a gentle compression, soft clipping, etc.), amongst audio enthusiasts, good luck with that quest....

Just because people like to toss out inaccurate ideas and terminology doesn't mean, within a scientific forum, that this should be acceptable. And BTW, I have never ever seen a cheap "tube buffer" that has "gentle compression" or "soft clipping." To achieve that actually takes some design skill, which is 100% lacking in the purveyors of those monstrosities.

 

[pkane]

More than just topology or tube choice or whatever. It's about engineering. If you say, "cathode follower using an ECC88," I can design that to be absolutely transparent with distortion levels in the 0.00x% range and the ability to maintain flat response when driving a cable and downstream devices OR I can "design" that device to have terrible distortion performance and a frequency response that droops when a cable and load are attached to it.

Neither of which, of course, has anything to do with whether there's a tube used. And the latter choice represents maybe half the cheap eBay tube "buffers," with the other half being "opamp, with the tube being essentially non-functional."



Just because people like to toss out inaccurate ideas and terminology doesn't mean, within a scientific forum, that this should be acceptable. And BTW, I have never ever seen a cheap "tube buffer" that has "gentle compression" or "soft clipping." To achieve that actually takes some design skill, which is 100% lacking in the purveyors of those monstrosities.

I've not used tubes in my system or DIY projects for well over 40 years. Recently I did some research on what others think tubes do to the sound. Specifically, I was looking for tube simulation in DSP. What most tube plugins try to emulate is the non-linear, often asymmetric, soft-clipping transfer function of the tube preamps. Some try to simulate the distortion produced by a guitar amp when pushed past the limit. Interestingly, a number of these simulations are actually patented and some as recently as a few years ago. A few actually try to emulate the behavior of each type of a tube and then derive the transfer function for the whole circuit from this basis, but most try to find a transfer function that resembles what a tube amp/preamp might produce. Here's one such simulation of a triode pre-amp, along with the harmonic distortion in the over-driven region of the tube:

In trying to reproduce this in my own software, I found the effect somewhat pleasant on some music and annoying on others. But then, I don't know how good a published simulation really is, or, in many cases, whether it attempts to reproduce the behavior of a specific amp or someone's generalized idea of what such amps might do to the sound.

 

[pma]

You may try one of my tests for diyaudio, which was an original vs. hybrid tube/SS amplifier.

https://www.diyaudio.com/forums/everything-else/330228-tell-original-file-tube-amp-record-test.html

As seen from the poll results, people were not able to tell reliably which is which. You need to download the zip file, it is not possible to play the wav files directly from the zipped archive.

 

[MattHooper]

I’ve used several tube preamps (with my CJ tube amps) and ended up keeping my CJ Premier LS2 preamp. All sighted listening so of no use here, but the system certainly sounds wonderful wether the preamp is perfectly transparent or not. And it has a remote control with is very useful to me, which is often absent on older tube preamps.

 

[bithloman]

Old thread bump, but i have one of those cheap tube buffer pre amps, with sensitive IEMs to make sure i could volume match two SS amps and just switch the wire, the tube pre amp ads "tube sound" whether its from the op amps or Chinese magic spells , the bass is thicker and the highs more extended "sounding", many have been measured and do change sound with different tubes installed the tubes run at almost 240 volts so its not just "a lightbulb for looks" i believe at 100db SINAD. its fun and cheap idk why people trash the idea. it sounds much more fun if its wrong or "inaccurate" who cares. @watchnerd @pma

 

[watchnerd]

Old thread bump, but i have one of those cheap tube buffer pre amps, with sensitive IEMs to make sure i could volume match two SS amps and just switch the wire, the tube pre amp ads "tube sound" whether its from the op amps or Chinese magic spells , the bass is thicker and the highs more extended "sounding", many have been measured and do change sound with different tubes installed the tubes run at almost 240 volts so its not just "a lightbulb for looks" i believe at 100db SINAD. its fun and cheap idk why people trash the idea. it sounds much more fun if its wrong or "inaccurate" who cares. @watchnerd @pmaView attachment 105264

Hi.

What are you @-ing me in reference to?

 

[Wes]

by "topology" I assume you guys mean the specific circuit design used, and not tubes shaped like Klein bottles?

 

[levimax]

It is an unusual concept that an obsolete technology used in a poorly executed and broken design is used to somehow "improve" something. I can't think of other examples of this outside of the audio hobby.

 

[mhardy6647]

by "topology" I assume you guys mean the specific circuit design used, and not tubes shaped like Klein bottles?

Are they easier or harder to evacuate than the regular old kind?



DSC_0001 by Mark Hardy, on Flickr

 

[egellings]

Since power amps are typically driven to full output power with a volt or maybe two volt input signal amplitude, I don't see where the added voltage swing of a tube preamp is any advantage, since a SS preamp with 15 volt rails can easily provide enough drive to get max output out of the power amp. It's no big deal.

 

[Daniel lombardy]

I would be concerned that these pre-amps are actually cheap SS amps with "tubes for decoration", I don't know specifically on these but I have seen this reported for similar products. Free advice and worth every penny is if I was going to get another tube pre-amp it would either be a well know vintage one or a DIY project. I would also be very skeptical of "tube rolling" .... if a tube pre-amp is working right it is not going to sound different than a SS pre-amp working right.... "rolling" in a different tube that sounded different would most likely indicate the tube is not working right in the circuit. In any case good luck and have fun.

I have the FX AUDIO T03 and the AIYIMA A3 Tube preamps and they sound very good. Also have the AIYIMA T9 Bluetooth Tube preamp. I don't recommend the T9, it is flawed. They are all upgadable by changing the NE5532P OPAMPS to better Texas Instruments

I have been flirting with some cheap tube preamps on Amazon for less than 100$. I see surprisingly positive reviews and the fact that stock tubes can be replaced sounds quite nice as I can play around with the sound and significantly(?) improve its quality.

My set up consist of a Geshelli stack (Enog 2 pro and Archel 2.5 pro) which feeds a HE4xx and the Edifiers S3000 pro. So, I want the preamp to colour the sound in the headphones and speakers.

Do you think it is money worth spend, or will I be disappointed by them, hence better increase my budget to get something better? What is your opinion/experience with these or similar products?

Examples on Amazon are the following:

SUCA-AUDIO Tube-T1 Preamplifier, Vacuum Tube Amplifier Buffer Mini Hi-Fi Stereo Preamp with Treble & Bass Tone Control for Home Audio Player (6K4 Tubes): https://www.amazon.com/gp/product/B07Q656449/ref=ox_sc_mini_detail?ie=UTF8&psc=1&smid=A18L48XDTDF0CW

AIYIMA Audio 6J1 Tube Preamplifier Bluetooth 5.0 HiFi Treble & Bass Adjustment Audio Preamplifier DC12V Amplifier Preamp for Home Theater System (Black+Bluetooth 5.0): https://www.amazon.com/dp/B07TX89D9...lja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1

Dilvpoetry 6K4 Vacuum Tube Amplifier NE5532P Chip Preamp 2 Channel Treble Bass Stereo Buffer Preamplifier(Silver):
https://www.amazon.ca/gp/product/B07HP38P9G/ref=ox_sc_mini_detail?ie=UTF8&psc=1&smid=A27GP0EZAO17FR

I Have the FX AUDIO T03 and the AIYIMA A3 Vacuum tube Preamplifiers. They sound very good and are easily upgradable by changing the Vacuum tubes.I am using the GE Jan 5654WA from Riverstone Audio on Amazon. I also change the OPAMPS to the Texas Instruments as well as the 1uf capacitors to WIMA, I purchased those at Mouser Electronics. Here is a great video on the subject.

. I did the upgrades and it made a significant improvement. Here is another useful video.

 

[SIY]

.. I did the upgrades and it made a significant improvement.

It kept you occupied and you had fun. Best yet, it didn't take any knowledge, just a credit card and a few hours.

But I'll remain skeptical about the reality of the "significant improvement." In fact, I'd put money on degradation if you did it like the guy in the video.

 

[mhardy6647]

Best yet, it didn't take any knowledge, just a credit card and a few hours.

That kind of somes up this whole hobby for some practicioners.