Tube Preamp for Benchmark AHB2 or Class D/SS Poweramp?

[Chris-E]

Hello dear ASR Community!

New member here who's been casually following ASR as a reader for a couple of years by now but never felt competent enough to contribute to the excellent discussions happening here...

Now here's my question:
Are there ASR members around who have experimented with, or thought about, adding a tube stage / preamp to their Benchmark AHB2 or comparable ultra-clean solid state power amps? If so, what did you do and how did that work out for you vs. your expectations?

I understand that this topic may be contested terrain, so please allow me to explain where I'm coming from:
After sadly not having had a proper stereo setup for quite a few years, I've started to build a new stereo setup from scratch about 3 years ago.

In a first step, and heavily informed by ASR, I wanted to build a solid-state reference signal chain (within my budget) that measures well and is as transparent / linear / uncoloured as possible; i.e., accurate sonic representation that is truthful to its source (High Fidelity). I spare you the boring details, but I ended up with the following setup:


Raspberry Pi (Moode Audio) --> USB --> RME ADI-2 DAC FS --> XLR --> Benchmark AHB2 --> Nubert NuVero 140


Besides the speakers, which don't get a lot of attention outside the German speaking part of Europe, this should look like a pretty familiar signal chain for the ASR community. It also sounds brilliant. Pin-drop quiet, excellent linearity, clarity, resolution. The transparency in representation reminds me of the Genelec and Dynaudio active monitors I occasionally get to enjoy at a friend's recording studio. It's quite fun to see how unforgivingly revealing this current setup is when it is fed sub-standard recordings, mixing, mastering -- bad audio engineering. It won't make bad recordings sound pleasant but expose them. On the other hand, since listening to this setup, I have learned to appreciate the craft of audio engineering in an entirely new way: Great musical performance paired with skilful engineering just sounds delightful on a different level!

So why would anyone want to "destroy" this clean chain by introducing "distortion" and "noise" via a tube stage?

Well... not to achieve objectively "better" or "more accurate" reproduction for sure. But after having listened to this setup for 2+ years, I am curious to experiment and discover new sonic signatures that I may or may not find "subjectively pleasing". I like to think of this as an experiment in taste rather than in reproductive accuracy. With the setup's core components selected for neutrality, I feel that a bit of playful hedonic sonic intervention via alternative signal paths should be in order. I agree that from a purely objectivist paradigm I'm ending up with an inferior (less truthful / accurate) representation. But hey, I just want to experiment with a new range of available sonic signatures in an otherwise quite accurate signal chain...

Here's what I was thinking about:
Two parallel signal paths. The first one as is. RME into AHB2 via XLR. The reference path.
The second path would be RME into a tube preamp/stage and from there to the AHB2. Both signal paths could be live switchable to allow for A/B comparison of sound signatures. Then, obviously, all the fun like tube rolling etc can begin... ;-)

Has anyone attempted or realised a similar setup with an otherwise "clean" solid state system? How did it go and what components did you use for the tube stage?

Thank you for sharing your thoughts! I very much appreciate your input!

All the best from the UK,
Chris

 

[HarmonicTHD]

Hello dear ASR Community!

New member here who's been casually following ASR as a reader for a couple of years by now but never felt competent enough to contribute to the excellent discussions happening here...

Now here's my question:
Are there ASR members around who have experimented with, or thought about, adding a tube stage / preamp to their Benchmark AHB2 or comparable ultra-clean solid state power amps? If so, what did you do and how did that work out for you vs. your expectations?

I understand that this topic may be contested terrain, so please allow me to explain where I'm coming from:
After sadly not having had a proper stereo setup for quite a few years, I've started to build a new stereo setup from scratch about 3 years ago.

In a first step, and heavily informed by ASR, I wanted to build a solid-state reference signal chain (within my budget) that measures well and is as transparent / linear / uncoloured as possible; i.e., accurate sonic representation that is truthful to its source (High Fidelity). I spare you the boring details, but I ended up with the following setup:


Raspberry Pi (Moode Audio) --> USB --> RME ADI-2 DAC FS --> XLR --> Benchmark AHB2 --> Nubert NuVero 140


Besides the speakers, which don't get a lot of attention outside the German speaking part of Europe, this should look like a pretty familiar signal chain for the ASR community. It also sounds brilliant. Pin-drop quiet, excellent linearity, clarity, resolution. The transparency in representation reminds me of the Genelec and Dynaudio active monitors I occasionally get to enjoy at a friend's recording studio. It's quite fun to see how unforgivingly revealing this current setup is when it is fed sub-standard recordings, mixing, mastering -- bad audio engineering. It won't make bad recordings sound pleasant but expose them. On the other hand, since listening to this setup, I have learned to appreciate the craft of audio engineering in an entirely new way: Great musical performance paired with skilful engineering just sounds delightful on a different level!

So why would anyone want to "destroy" this clean chain by introducing "distortion" and "noise" via a tube stage?

Well... not to achieve objectively "better" or "more accurate" reproduction for sure. But after having listened to this setup for 2+ years, I am curious to experiment and discover new sonic signatures that I may or may not find "subjectively pleasing". I like to think of this as an experiment in taste rather than in reproductive accuracy. With the setup's core components selected for neutrality, I feel that a bit of playful hedonic sonic intervention via alternative signal paths should be in order. I agree that from a purely objectivist paradigm I'm ending up with an inferior (less truthful / accurate) representation. But hey, I just want to experiment with a new range of available sonic signatures in an otherwise quite accurate signal chain...

Here's what I was thinking about:
Two parallel signal paths. The first one as is. RME into AHB2 via XLR. The reference path.
The second path would be RME into a tube preamp/stage and from there to the AHB2. Both signal paths could be live switchable to allow for A/B comparison of sound signatures. Then, obviously, all the fun like tube rolling etc can begin... ;-)

Has anyone attempted or realised a similar setup with an otherwise "clean" solid state system? How did it go and what components did you use for the tube stage?

Thank you for sharing your thoughts! I very much appreciate your input!

All the best from the UK,
Chris

There is a much much cheaper and more controllable and adjustable way of introducing any kind of effects (including noise, distortion, …. you name it….). Temporarily replace your Pi with a PC and run a DAW with all the effects you want. You can even download effects simulating tube amps, or take the VST plugin from one of the forum members allowing you to dial in any distortion you want. This way you can experiment without having to change the effect machine (tube amp) physically.

Edit. And yes it seems a pity to run distortion into an AHB2. But hey if it serves your curiosity. Your amp.

 

[fpitas]

Seems like a terrible waste of an AHB2. You could maybe try a SET amp if you want fuzzy stuff.

 

[DMill]

If you have to go tubes for the pre amp, I think Schitt offers one you can bypass the tubes if you wanted? That way you can have your cake and have a more palatable measured sugar content you might like eating better?

 

[Chris-E]

There is a much much cheaper and more controllable and adjustable way of introducing any kind of effects (including noise, distortion, …. you name it….). Temporarily replace your Pi with a PC and run a DAW with all the effects you want. You can even download effects simulating tube amps, or take the VST plugin from one of the forum members allowing you to dial in any distortion you want. This way can can experiment without having to change the effect machine (tube amp) physically.

Thanks a lot for this! I am aware of these plugins and it's something I may definitely try.
But then, there's a certain fascination that comes with the materiality of tubes and actual circuits... Why do people still appreciate mechanical watches when digital ones are objectively superior when it comes to keeping accurate time? I think I'd enjoy the physical engagement more than a software emulation... But I'll give it a try for sure!

 

[Blumlein 88]

Plus, good tube pre's aren't audible much. Something of a myth as much as anything.

 

[Chris-E]

Seems like a terrible waste of an AHB2. You could maybe try a SET amp if you want fuzzy stuff.

Hence two parallel signal paths. Nothing is lost by increasing the number of options, right? The reference path will remain clean...

 

[Chris-E]

If you have to go tubes for the pre amp, I think Schitt offers one you can bypass the tubes if you wanted?

Yes, I've considered the Freya+. Just curious if members had real world experience with such a setup or similar and how their (very subjective) results sounded like...

 

[HarmonicTHD]

Thanks a lot for this! I am aware of these plugins and it's something I may definitely try.
But then, there's a certain fascination that comes with the materiality of tubes and actual circuits... Why do people still appreciate mechanical watches when digital ones are objectively superior when it comes to keeping accurate time? I think I'd enjoy the physical engagement more than a software emulation... But I'll give it a try for sure!

I enjoy my expensive watches because of the design (and maybe because of the status symbol) but not because they keep time accurately. These are completely different objectives.

If you just like the look. Buy a cheap tube amp put it on your cabinet just don’t hook it up and listen as before. Just a thought.

 

[Ron Texas]

No way.

 

[Chris-E]

Plus, good tube pre's aren't audible much. Something of a myth as much as anything.

Interesting... I've done a bit of research and stumbled over this video and some other sources who believe otherwise:

It kind of makes sense to me that tubes are objectively inferior in a power amp, especially when paired with not super efficient speakers. Hence the idea to let SS do the heavy lifting and infuse the colour when less amplification is needed? But I've never had a tube component. Hence the question.

 

[Chris-E]

I enjoy my expensive watches because of the design (and maybe because of the status symbol) but not because they keep time accurately. These are completely different objectives.

If you just like the look. Buy a cheap tube amp put it on your cabinet just don’t hook it up and listen as before. Just a thought.

Grant you that of course. Some people appreciate mechanic watches also for the craftsmanship, tradition, heritage of the watchmaker, complications, etc...
So I see where you're coming from, but that's not the only reason why someone may be into mechanic watches.

 

[Chris-E]

No way.

Haha... the idea of introducing tubes to my signal chain? That bad?

 

[HarmonicTHD]

Grant you that of course. Some people appreciate mechanic watches also for the craftsmanship, tradition, heritage of the watchmaker, complications, etc...
So I see where you're coming from, but that's not the only reason why someone may be into mechanic watches.

Yes million of reasons. But certainly not for accurate time keeping (analogy of accurate signal reproduction)

 

[HarmonicTHD]

Haha... the idea of introducing tubes to my signal chain? That bad?

Yes

 

[Blumlein 88]

EQP-WA Pultec Style Tube Equalizer | Warm Audio

The EQP-WA is a re-creation of the most renowned tube Equalizer in studio history, the “Pultec EQP-1A”.

warmaudio.com

Try a pair of these. Expensive at $799 a channel. All tube, transformers (where tube sound is when there is one), and still goes thru transformers and tube with EQ bypassed. Balanced outputs and inputs too. Also has very adjustable EQ so you can definitely monkey with the sound. Recreation of the Pultec tube EQ units.

 

[Chris-E]

Yes million of reasons. But certainly not for accurate time keeping (analogy of accurate signal reproduction)

That's great, so we agree! I acknowledge in my post that tubes would reduce the accuracy of reproduction. Yet, as with mechanic watches, there is more than one subjective / hedonic way to appreciate sound or a time piece...

 

[Chris-E]

Yes

But... what harm could it possibly do to experiment? It's cool with me if not everybody's keen to try....

 

[HarmonicTHD]

You can also take this test. It will give you an objective idea what level of distortion you can hear and what it sounds like. You can then compare that to a tube amps distortion and decide if it’s worth your while.

Listening Test

www.klippel.de

 

[Blumlein 88]

Just to fill in, mostly tube pre's aren't very audible if at all. Tube power amps for a number of reasons are. Oh, and don't listen to the guy at PS Audio. He spouts lots of misinformation. Don't know about that particular video, but just not a good source of information.