Tube type acoustic guitar amp??

[Spook]

Lots of tube generalizations in this thread that aren't quite right. I would note the current use of tubes in high end stereo gear and in front end preamps in the studio. There may not be a tube amp on the market designed for high fidelity acoustic guitar applications and if there were it would be heavy and expensive. But properly designed, it would sound great.

I use a Palmer PDI-CTC in front of an Acus AD (similar to a Schertler Roy) all the time and you can certainly hear how it warms the sound.

[SpruceTop]

Originally Posted by outatune

In a related thread someone asked opinions concerning an amp for an 814 and a Vox AGA150 amp was mentioned and was said to be a tube amp. I did a little research and found it does indead have a 12AU7 vacuum tube in the preamp. I have never heard of such an amp but I am really curious.

Does this amp make a difference in the sound of an acoustic guitar that is really superior?? I currently play a Taylor through a Loudbox 100 and have been perfectly happy. I know vacuum tubes make a tremendous differnce in regular guitar amps but what about in an acoustic situation??

I live in a small town and the closest large music store is several miles away so it is difficult to just run out and try one.

Is this AGA150 worth trading my Loudbox for??

I have a VOX AGA 150 and it sounds good but the tube effect is subtle, it's kind of like a Takamine CoolTube preamp but the VOX isn't variable and can't be driven into distortion like the Takamine CoolTube. You can't control how much tube-tone is in the signal. Frankly, if you're looking for acoustic-amp tube tone, I'd check out the Rivera Sedona Series Amps.

[Charmed Life Picks]

Spruce, is the Rivera the amp you're playing out with these days?

Thanks,
Scott

[SpruceTop]

Originally Posted by Charmed Life Picks

Spruce, is the Rivera the amp you're playing out with these days?

Thanks,
Scott

Hi Scott, I don't have a Rivera but I have the LR Baggs Synapse, which is a good PA speaker but it doesn't have any tube circuitry.

[Herb Hunter]

Originally Posted by Spook

Lots of tube generalizations in this thread that aren't quite right. I would note the current use of tubes in high end stereo gear and in front end preamps in the studio. There may not be a tube amp on the market designed for high fidelity acoustic guitar applications and if there were it would be heavy and expensive. But properly designed, it would sound great.

I use a Palmer PDI-CTC in front of an Acus AD (similar to a Schertler Roy) all the time and you can certainly hear how it warms the sound.

I’m here to say that a high-end tube design would sound great but not better than solid-state circuitry and would have the drawbacks of much greater cost, greater heat and constant tube deterioration.

[Spook]

Originally Posted by Herb Hunter

I’m here to say that a high-end tube design would sound great but not better than solid-state circuitry and would have the drawbacks of much greater cost, greater heat and constant tube deterioration.

Not drawn to the argument of tube vs. solid state. Kind of pointless given the thousands of posts of this topic that can be found on hifi and music boards. They are different. Some prefer tubes and find the drawbacks manageable.

[ethanay]

In my experience, for amplifying acoustic, I have found that the pickup/preamp is at least as (if not more) important than the amp and speaker. I have played through all sorts of cheap FRFR PAs and always sounded decent with a good preamp and pickup system, and a compressor on a really subtle setting. And a teeny bit of reverb. And...just kidding. I think I'm done with that thought.

I think a well-designed tube signal path can help add another 10-15% of pleasantness to the sound quality for both electric and acoustic (distorted or clean). And especially when distortion is involved.

For amplifying any distorted signal, I think a low-pass/high-cut filter is obligatory. A tweeter-less speaker cab design usually accomplishes this right out of the box. But then it comes down to whether you prefer that attenuated high-end for your acoustic, as well. I don't. It sounds too "electric" to me. IMO, a defeatable tweeter is important if it will serve in both clean and distorted purposes (e.g., as a pedal platform for electric that will have any distortion). I am in the process of working out if I like the sound of a low-passed electric signal into a FRFR cabinet.

I have come across very well-designed solid state circuits that sound good-great, much better than poorly-designed tube circuits. But my ears and body still prefer the sound and feel of a well-designed tube circuit. That said, I haven't compared something like a Quilter to my Rivera Chubster 40. I really WANT to ditch tubes, and actually am actively trying to. But the sound and feel will be the ultimate deciding factor. I will continue to put up with the added cost/weight/size if I need to.

I think a lot of solid state circuits are designed "too clean" if that makes sense. A lot of the warmth and fatness from good tube circuits I think I remember reading comes from imperceptible but pleasing distortion that the circuit adds to the signal. My ears definitely tend to agree. I bet the technology is there where someone can design some class D power amps that behave a lot like a well-designed tube circuit.

But man, I am eyeing that Rivera Sedona Lite 25 watt amp...it ticks all the boxes. (Jeez I think I said that already)

[ezellohar]

I agree with the one saying there are too many generalizations on the topic.
I try to put together some opinion, coupled with the little knowledge I have in high end audio.
First of all, what are we thinking "tube sound" is? I think this is the real question here, the mental projection we have of the tube sound, not concerning gear at all.
I'll try a few examples.
Maybe we think of that "tube sound" as a warm sound, with a rich harmonic content, thick and with silky highs. Could it be a good generalization? On the contrary, a "not-tube sound" is a very detailed sound, with a more clean and cold sound.
Well the former is a good description (as far as words can describe sounds) of a Neve 1073 preamp sound. The neve 1073 is one of those holy grail preamps, used in famous studios and which made a "sound" so characteristic that artists all over the world sought to have. Well, the Neve 1073 is a solid state preamp, no tube there.

My point is, often the infamous "tube sound" we seek, is the colour of the preamp, which is not related to the preamp architecture.
The Neve 1073 is a very colored preamp, the API 512 is another one (used a lot on electric guitars recording for its color and character), both solid state.
The Avalon VT-737 instead, is a very clean preamp, with little coloration, and a lot of details. And it's a tube pre.

Maybe, we're biased due to electric guitar amps, which are designed in a totally different way: there the preamp wants to color the sound, and wants to add harmonic content, together with compression. So tube (pre)amp=color.

Coming to our acoustic guitars, do we want a colored preamp? Well, IMHO, the answer is not easy. While I do love the recordings with the 'neve sound', we have to keep in mind that the finished sound is the sum of a lot of factors. The sound source (pickup or mic? mic placement, different kind of pickups lead to very different sounds), preamp, eq, (compression), reverb to name a few.
A pickup (any kind) as a very distinctive sound, which, we know it well, is totally different from the sound of the real guitar. the preamp could color the source sound in a way that is less than desiderable, if said pickup put out frequencies that we don't like (just saying: the frequencies spectrum under the saddle is very different to the one standing 1m away facing the guitar, so is the one under the soundboard, or in the soundhole and so on).
My two cents is that a cleaner preamp here is better, or a preamp designed on the characteristics of the sound source in mind (which is what most pickup producers do: they made a custom-tailored preamp to pair the pickup with), so most of the harsh frequencies are tamed. Then, we can use outboard to shape our sound, and a few solutions comes to mind. A tonedexter is a great tool to make the source sound more similar to mic'ed sound of that guitar. another way is to pass the sound through an eq with a lot of bands, making a similar process. Izotope matching eq does this, and it can be converted to an IR to use it live with an IR loader (which I remember seeing Doug Young doing exactly this in a video).
One last, obviously personal, consideration. Often we seek the best sound for our guitar, forgetting the mix. i.e. the 'best' sound in a vacuum is not the best sound in a band. when shaping my sound, I cannot make my guitar big, thick, warm if that collides with other instruments or voices. each and every instrument/voice shall and must have its own space in the mix, and a good chunk of this is accompliced by not fighting over the same frequencies. maybe I'm stating the obvious here, but I try to make myself a reminder. Am I alone or not?
Going a little OT, also what helped me a lot to understand (and so improve) my sound, is recording. If possible, try to record your performance and feed that to you PA, and listen to it without playing. First, the PA itself changes the sound, for better or worse, but if you want a good sound, I have to be aware of this, and account for. Second, our perception (mine at least) is very biased by the acoustic sound of the guitar we're playing. we have to listen to the amplified sound alone to be really aware of what is good and what is not. so record and listen, if you hear me
Sorry for the long post

[cdkrugjr]

According to a guy who comments Weekly on That Pedal Show, what we REALLY need to sound better is more practice time...

An audiophile stereo tube amp is Not the same as a Plexi. If you're operating well below the clipping threshold of your circuit (regardless of whether it's silicon or vacuum...) it's not going to distort or compress audibly.

It comes down to how the circuit is designed and how hard you're driving it.

On the other hand, last night we had a Classical player show up for a choir rehearsal with an electric SS practice amp. Sounded awful 'cuz it was for Electric...

[Herb Hunter]

Originally Posted by ethanay

...I think a lot of solid state circuits are designed "too clean" if that makes sense.

If the object is accurate reproduction, then I’m in the position of having to say that it doesn’t make sense. It is like saying that a camera’s color accuracy is too correct.

[Spook]

Originally Posted by Herb Hunter

If the object is accurate reproduction, then I’m in the position of having to say that it doesn’t make sense. It is like saying that a camera’s color accuracy is too correct.

And yet we judge lenses by their bokeh.

The object is not accurate reproduction. That is relatively easy. And if done with say, a piezo pickup, you get a nasty, nasally, awful sound. So we add EQ, we add processing, and some like to add tube circuits that color the sound.

There is nothing wrong with tube preamps. Or solid state. Based on what you're doing and what product you choose, you can get a nice warm, round, soft edged sound with either. If that's what you want. I like the Palmer PDI-CTC because it's easy to dial in, sounds great, and doesn't weigh much. If it were solid state instead of tube based, I wouldn't care.

People should just choose what they like based on their own research, trying to understand their own requirements (harder than it sounds), and using their own ears. Also wouldn't hurt to ignore broad generalizations they find online.

[Herb Hunter]

Originally Posted by Spook

And yet we judge lenses by their bokeh.

The object is not accurate reproduction. That is relatively easy. And if done with say, a piezo pickup, you get a nasty, nasally, awful sound. So we add EQ, we add processing, and some like to add tube circuits that color the sound.

There is nothing wrong with tube preamps. Or solid state. Based on what you're doing and what product you choose, you can get a nice warm, round, soft edged sound with either. If that's what you want. I like the Palmer CTS-PD1 because it's easy to dial in, sounds great, and doesn't weigh much. If it were solid state instead of tube based, I wouldn't care.

People should just choose what they like based on their own research, trying to understand their own requirements (harder than it sounds), and using their own ears. Also wouldn't hurt to ignore broad generalizations they find online.

I agree people should make informed choices based on their preferences and that not everyone cares about accurate sound amplification. However, it is a fact, not a generalization, that tube amps do not amplify input signals as faithfully as solid state amplifiers. The lowest distortion tube amps I can find have a harmonic distortion rating of 0.5% as compared to solid-state amps which can be as low as 0.005%.

[ethanay]

Originally Posted by Herb Hunter

I agree people should make informed choices based on their preferences and that not everyone cares about accurate sound amplification. However, it is a fact, not a generalization, that tube amps do not amplify input signals as faithfully as solid state amplifiers. The lowest distortion tube amps I can find have a harmonic distortion rating of 0.5% as compared to solid-state amps which can be as low as 0.005%.

I was just going to make that distinction: there's "accurate" (only louder) and "good."

"Accurate" does not always = "Good." And find the pickup/impedance/loading/preamp is often to blame. An accurate reproduction of a crappy signal chain, well...and trying for a deliberately-inaccurate reproduction to compensate IMO just creates a mess of the signal chain.

It's kinda like the recording process in general. "Get it right" as close to the source as possible vs the trap of "fix it in post" attitude.

If there are problems earlier in your signal chain, a tube amp probably isn't going to address those issues. If you have a crappy pickup, or an incorrectly installed one, get that fixed. If you have a crappy (or no) preamp, get that fixed. If you have crappy technique, get that fixed If you are playing crappy songs, get that fixed

So, with that out of the way, assuming that someone has a good pickup system, preamp, impedance matching, etc (I don't pretend to understand all the factors at play, but I sure as hell can hear the difference when I plug in direct from my K&K pickups vs through a good preamp first)...I do think that a tube-based circuit does sound sweeter, in part, because, YES, it does distort/compress more (inaudibly), and it tends to do so in harmonically-pleasing ways. Vs solid state. So that last bit of difference of what people hear is partially the different ways the circuits handle whatever distortion they do produce.

EG, Tim Pierce almost always uses a "dirty" clean sound that is *just* shy of audible distortion. It reminds me of therapeutic microdosing discussions around shrooms/pot/acid. You are going for a "subperceptual" effect. The effect is there, but is not DIRECTLY observable. You can only observe artifacts or symptoms. Same with tube distortion in this particular application.

So, yeah, a tube amp might have slightly lower fidelity, but people still prefer them because it is typically more pleasing to the ear, and that's ultimately what matters, right? (and does this difference only occur at volume?)

Lastly, using the Rivera Sedona Lite as an example, they also use a relatively huge magnet on their custom-designed "liquid cooled dome tweeter" and claim that this has a noticeably positive impact on the highs. I don't doubt it. Speakers/cab design have an arguably huge impact on sound. I am willing to bet that it has a bigger effect on fundamental tone than the absence/presence of tubes.

All that said, I do love what slightly-saturated tubes do to a good signal path. Harmonic enhancement + slight compression. Not really noticeable as distortion per se. But, yeah, technically, it is a form of distortion of fidelity, I guess.

So the question isn't, "Does this add distortion," but "Does the distortion that this amp adds (if any) enhance vs degrade the signal?"

[loco gringo]

Try one of these for $325.00.

http://www.sarnomusicsolutions.com/products/sgbb.html

[SpruceTop]

Originally Posted by loco gringo

Try one of these for $325.00.

http://www.sarnomusicsolutions.com/products/sgbb.html

It looks very interesting. Do you have actual acoustic-guitar amplfication experience using this Sarno Musical Solutions Steel Guitar Black Box device? I wonder how its tube-tone output would fare against the digitally-based LR Baggs Session Acoustic DI's Saturation circuit? I have a NOS, circa 1960, RCA 12AX7 "Black-Plate" tube that I could swap out with the factory-installed, foreign-made new one in the Sarno Steel Guitar Tube Preamp. I'm tempted to get this preamp!