Tube type acoustic guitar amp??

[Herb Hunter]

Originally Posted by Joseph Hanna

I am sooo, sooo totally with you here Gerry. I've been posing similar"how come nobody makes an amp like this" posts here and other forums for some years now.

Here's the thing for me. If we take, as an example, ANY current acoustic guitar pickup system (K&K, LR Baggs, Fishman, PUTW, Highlander and the other 2 thousand entries on the market) each and every one of them represents a dramatic departure from what is actually a true acoustic guitar sound. It's just a fact it's no longer "my guitar only louder". That's an empty mantra. In virtually every case the pickup system departs from the actual sound of the guitar.

As an extension then to that thought, I have never understood the industry mindset that an acoustic amplifier must gravitate towards being deadly accurate clean. Like a mini PA. That somehow a pleasant sonic footprint from an amp (perhaps with tubes) is a no-no for acoustic guitarist. As if an LR Baggs Anthem is so organic that it must be amplified with the utmost accurate response. You can argue ss specs and cleanliness until the cows come home but why would you want a McIntosh amplifier to amplify your Baggs Element pickup? The result would be piezo bad, but loud and clean. Give me some harmonic content, some hair, some roundness. Something to tame the ills and round the edges of acoustic pickup systems. It doesn't mean distortion or at least distortion in the "electric guitar" sense.

I dunno, but for me it's hard to argue all of the current acoustic guitar pickup systems don't need a little (to a lot) of sonic help. I don't want my Fishman piezo to be dead balls accurate and loud.

I can't afford a Humphrey but if I could I'd be all over it. This seems like a tremendous leap in live, pickup equipped, acoustic guitar amplification. It also seems like something that could be mic'd to a larger PA if needed.

I want one!!

Gerry if you ever need someone to run around and demo your amp.......I'm your Huckleberry

You are making the assumption that the Humphrey amp is designed to color the sound of a guitar pickup, intentionally adding harmonics that the pickup is not delivering. I note that the Humphrey Amplifiers website states that "for clarity, circuit uses some hi-fi tube amp design techniques" which suggests the goal was accurate reproduction (as opposed to colored reproduction). A further indication is the use of a speaker described as a hi-fi type.

Do you know for a fact that the Humphrey amplifier was designed to deliver a frequency response that deliberately departs from flat (frequency response distortion) or that it was designed to add harmonics not present in the input signal (harmonic distortion)?

[Joseph Hanna]

Originally Posted by Herb Hunter

Do you know for a fact that the Humphrey amplifier was designed to deliver a frequency response that deliberately departs from flat (frequency response distortion) or that it was designed to add harmonics not present in the input signal (harmonic distortion)?

I do not know for a fact anything about design intent. My old neighbor and good pal out in Topanga has one. I've played it at living room levels and I loved the bloom and touch and tone. Perhaps the end of that story but where my love of tube stuffs continues. It without any question imparts a feel, a touch and a tone that I have yet to encounter. I'm not an amp designer nor (at least for guitar oriented stuff) a spec chaser. What I do trust (as old as they're getting) is my ears and my sense of touch and dynamics on the guitar.

I think the general state of the sonics in amplified acoustic guitar world could use some help. All design intents and specs aside and in my world this (tube amps for acoustics) is a step in the right direction.

No offense to Fishmans fine product line but I'm just never gonna get moved or inspired musically, sonically, dynamically by a Fishman Loudbox Artist. It's a great product but not a particularly musical experience.

I like the trend

[ValveMan]

Originally Posted by Joseph Hanna

I do not know for a fact anything about design intent. My old neighbor and good pal out in Topanga has one. I've played it at living room levels and I loved the bloom and touch and tone. Perhaps the end of that story but where my love of tube stuffs continues. It without any question imparts a feel, a touch and a tone that I have yet to encounter. I'm not an amp designer nor (at least for guitar oriented stuff) a spec chaser. What I do trust (as old as they're getting) is my ears and my sense of touch and dynamics on the guitar.

I think the general state of the sonics in amplified acoustic guitar world could use some help. All design intents and specs aside and in my world this (tube amps for acoustics) is a step in the right direction.

No offense to Fishmans fine product line but I'm just never gonna get moved or inspired musically, sonically, dynamically by a Fishman Loudbox Artist. It's a great product but not a particularly musical experience.

I like the trend

Thanks for the +1 Joseph

[ValveMan]

Originally Posted by Herb Hunter

. . . Do you know for a fact that the Humphrey amplifier was designed to deliver a frequency response that deliberately departs from flat (frequency response distortion) or that it was designed to add harmonics not present in the input signal (harmonic distortion)?

Hi Herb,
There's a review/article in the ToneQuest Report this month - it gives you some good background on the design goals.

The key is what your ears actually hear coming from the guitar (Joseph kinda nailed it) is different to the signal that a pickup is delivering to an amp. When it's sitting on your lap you're hearing all kinds of nuances in the sound that a typical pickup system doesn't register. Connect that to a typical amplifier/PA and you may (or may not) get an amplified sound that you like.

Check out the article & let me know if you have any questions (link to pdf below).
https://www.onlinefilefolder.com/pub...h=aaKi6aLFTUFc

Best
Gerry

[Herb Hunter]

Originally Posted by ValveMan

Hi Herb,
There's a review/article in the ToneQuest Report this month - it gives you some good background on the design goals.

The key is what your ears actually hear coming from the guitar (Joseph kinda nailed it) is different to the signal that a pickup is delivering to an amp. When it's sitting on your lap you're hearing all kinds of nuances in the sound that a typical pickup system doesn't register. Connect that to a typical amplifier/PA and you may (or may not) get an amplified sound that you like.

Check out the article & let me know if you have any questions (link to pdf below).
https://www.onlinefilefolder.com/pub...h=aaKi6aLFTUFc

Best
Gerry

Thank you for the link. I plan to read the article this weekend.

[kramster]

Originally Posted by DHone

I have the K&K progression tube preamp. It uses two tubes.

I have one of those...never worked right...sigh... thought it was gonna blow up my amp a couple times...always somethin'

[DHone]

"I have one of those...never worked right...sigh... thought it was gonna blow up my amp a couple times...always somethin' "



you can really only turn the tube gain to about 9:00 before distortion. You then have to compensate for signal strength on the amp or PA. It worked well for me in a band context but I do find it a little too noisy for solo stuff. I do like the sound of the KK progression and mini combo but I have since moved to other solutions for plugging in.

[woa_horsey]

I just don't think tubes and acoustic guitars go together. The heart of acoustic tone is in the mids and tubes are typically all high-end and low-end with very little mids. I won't use a tube preamp to run my mics through when recording acoustic either. When you go to do something that requires a good deal of responsiveness from the guitar such as hammer-ons, pull-offs, fret taps, harmonic slaps etc. you need the mids there for that. Take away the mids and you take away a guitar's responsiveness. If you ever tried to dial out some mids to get rid of quack from a pickup then you already know what I mean about losing respsonsiveness when taking out the mids. Having said that, I'm sure there must be some tubes out there that are voiced to produce plenty of midrange if you could find them.

[jbefumo]

Just watched the video and am really impressed! Am in the process of building an amp for my own use, and was thinking along the lines of a dedicated 'acoustic' channel, which is how I found this thread.

Love the cabinets, too!

Joe
http://www.wattwerx.com

Originally Posted by ValveMan

I know this thread's a couple of months old, and that I might be inviting all kinds of criticism and nay-saying, but regardless, I can't resist throwing in my 2c-worth.

I'm the designer & builder of the Humphrey Amp mentioned above. It took over a year of full-time 7-day weeks to finalize the design & testing (I might be slow, but I'm big
First, I'll point out some obvious negatives, which really isn't good marketing practice - but I'm not marketing here, just explaining why I do what I do, so I guess it's ok.
1* Cost - yup, tube amps are more expensive than solid-state in general, and as mine are hand-built starting from raw lumber, and hand-wired, they are even more expensive - but they're certainly not targeted at the general market.
A typical solid-state amp can be made with a bill-of-materials total cost that is less than the cost of a pair of quality EL84's

Don't get me wrong - there's some fine s.s. amps out there and the fact that they CAN be made at low-cost and in high volume gives a lot of folks access to good gear.

2* Weight - yup, a Humphrey Amp weighs about 37lbs, depending on the wood used. We do need some hefty transformers. Actually more hefty than those used in electric guitar tube amps (don't want to saturate the xformer in an acoustic amp).
Also - we use a very heavy hi-fi class 10" speaker and brick of a horn-tweeter (all for good reasons)

3* Reliability. Depends what you're doing with it really. Tubes do wear out over time, but it depends largely on the voltage supply and how long they're played. My Marshall amp drives the EL84's with more than 420V (they're spec'ed for 300V) and after 5 years I'm thinking it's time for new tubes. I just use it for personal playing though - not gigging every night.
A Humphrey Amp using high quality JJ EL84's, running at much lower voltages, would run for many years before the sound degraded - unless you ride it hard & put it up wet every night of the week, of course.

There's actually fewer components & connections in a well-designed tube amp, so the reliability is inherently 'better' from the get-go.
It depends on a lot of factors though, and I'm not saying S.S. is inherently unreliable.
If I were to play the most important gig of my life & could choose only one amp, it would certainly be a (good) tube amp.

Okay - the positive stuff
1* I think it was Rollie that pointed out that some of the finest hi-fi amps in the world use vacuum tubes, so I'll not repeat what he said already. He's right, but I'd say that MOST of them use tubes. There's reasons for that.

We use a similar design methodology in our acoustic amp - it's all about the signal quality. In an electric guitar tube amp, everything about the design contributes to shaping, coloring and distorting the sound in ways that are pleasing to our ears. Understanding those things means that we can avoid the stuff that would be considered nasty for acoustic guitars, while still benefiting from the acoustic qualities that only tubes can deliver.

As Edward said . . . " . . The "correct" tube amp for the acoustic guitarist has to be designed thusly from the get-go, . . . "
Well said.

Add some secret sauce in the cabinet/speaker design and you have an amp that will cause you to pick up and play your guitar for longer, and more frequently (that's what my customers tell me).

Because it's not cheap to make, we figured it needed to bring as much to the table in aesthetic appeal as it does in sound quality, giving it some 'collectability' value, like one of the fine guitars it would be married to.
Like I said - I know it's not everyone's ideal, so don't knock us for going out on a limb with what we believe is solid product that meets an unmet need (yes, it's a niche market, but we're happy to serve it).

The interest is growing rapidly, I'm happy to say, and we're totally pumped at the reaction we get from folks that try/buy them.
There's a really nice video of Al Petteway doing a demo if you'd like to check it out. http://www.youtube.com/watch?v=k4Wm0nl1tWk

Hopefully, this late night rambling will be received in the spirit in which it was given. I'm just offering a perspective & an explanation for why there's yet another piece of cool gear available for ACOUSTIC guitar enthusiasts. Maybe some of what I said is helpful in some way - I hope so. I don't intend to engage in arguments or respond to slams - but I'd sure welcome any good questions or fair comments.
Thanks!
Gerry Humphrey

[jbefumo]

Well, this is certainly true if you're miking your high-end acoustic, but if you're plugging in a piezo-equipped model, then a pristine, transparent reproduction is simply going to amplify that brittle piezo sound. There's no reason a purpose-designed tube amp can't offer advantages to an acoustic-electric in crafting a convincing acoustic tone.

Originally Posted by Murphy Slaw

As an electric lead guitarist in bar bands for many decades I'm all about tube amps. My favorite amps even have tube rectifiers, and my Mesa Blue Angel uses a combination of 4;EL84's AND 2;6V6's along with 5;12AX7 preamp tubes.

I would NOT want a tube in an acoustic guitar amp. Tubes are still used in (electric) guitar amps because they distort, even if slightly, the signal.

Acoustic guitar amps were INVENTED, and are voiced, to give us a nice clean acoustic sound.

This is, of course, my opinion. (but I'm right.....)

[clintj]

Tubes, in a properly engineered circuit, can sound very nice. After all, there are several vocal mic preamps out there that use tubes - I use a pair in my PA rack for the vocal channels, and have run a saxophone through one of them with a nice dynamic mic and gotten very good results. I've also run my 12 string through a Fender tweed Champ and been very surprised. Not much more than a preamp tube, power tube, and a volume knob in that circuit.

[ethanay]

Just to update/summarize some good information here in this thread. Caveat I am a lay person. I am not a tech but have talked to more than a few experts about this to wrap my mind around it.

I just talked to my local amp tech. He uses the same tube amps for electric, acoustic and bass. He just changes out the cabinets. This misses some dedicated features, but nothing that couldn't be added back in with one or two pedals.

A tube-based acoustic guitar amp can (and often does) sound really really nice. As others said, more important than the tube vs solid state question is the design: circuit (including tone stack and power amp) and speaker/cabinet.

Circuit:
Acoustic: hi fi high headroom circuit, the distortion you hear is just that inherent in the use of tubes, which is generally pleasing and still considered "hi fi"
Electric: typically lower headroom, bringing in noticeable overdrive.

Tone stack:
Acoustic: typically specialized for acoustic guitar frequency tweaking. One of the most notable/common designs is increased control over the mids, either with multiple mid controls and/or a notch filter or similar circuit for feedback control.
Electric: typically a relatively-simplified EQ compared to bass or acoustic.

Speaker/cab
Acoustic/bass: Often (but not always) uses a high power handling/high headroom flat response woofer with a tweeter or horn (and a crossover) to handle the high frequencies.
Electric: Typical speaker/cab design emphasizes mid range and acts as a high-pass/low-pass filter. This is especially important when playing distorted electric guitar. Less important for clean sounds.

In short, if you like the way the amp SOUNDS and/or works with your instrument, and can run an appropriate speaker/cab with it, you can use the amp for that instrument. It sounds pretty cool when a saxophonist plays through a Our idea of specialized amps for every purpose is a really recent (not necessarily bad) development. Lots of records were made with bassists plugging into Marshall stacks, Fender Twins, etc (according to my tech, don't ask me for specifics!).

IMO the Rivera Sedona Lites got it all correct (on paper): High headroom two channel circuit design, defeatable frequency notch, one input per channel (including a lo-z, balanced input from preamps or microphones), defeatable tweeter for electric guitar.

[BuleriaChk]

If your pickup/preamp is fine, then all most acoustic amps need (for me) is a bit of overdrive (I play nylon string, so use FRFR and usually a bit OD is all I ever need), but most acoustic amps (for steel string) have chorus, reverb, etc., but don't include overdrive... which gives a bit more sustain...

[phcorrigan]

Originally Posted by Herb Hunter

The problem with tubes:

1. They begin to deteriorate from the moment you first turn them on.
2. Tube amps typically have much higher distortion levels before the onset of clipping.
3. They cost more.

Most people favoring tube amps, in applications other than for electric guitars, do so for romantic reasons.

4. They weigh (a lot) more.

[RockerDuck]

Many played their acoustic (with electric guitar pickup installed) through the same amp they played their guitar through in the 60's and 70's. The Twin Reverb is a great acoustic amp. But also many played through a Roland Jc 120 too, which sounded good too.