| Author | Message | ||
| slej |
I've got a Music Man 130HD Reverb amp. What class is it? Is it push/pull? | ||
| Steve Kennedy |
You posted this in an area most people won't see (it is off-topic), might I suggest that next time you try to post messages in a Topic that applies to the question and you'll get more exposure. All Music Man "tube" amplifiers are push-pull (two or 4-tube output stages that use a phase-splitter). This amplifier topology is called Class A/B (push/pull). The preamp is considered to be "Class A", and the push-pull output stage is Class B. The two together form a Class A/B system, similar to most guitar amps. Class A/B amps have lower temperatures and higher power (at the expense of higher distortion) and a different sonic character than a Class A design. The Vox AC-30 and all its clones (i.e. Matchless, etc.,) are Class A all the way through (single-ended output stage). Class A generates a lot of waste heat but is lower distortion (and low power) and has a smoother sonic character (due to the harmonic structure of the output waveform). | ||
| Marc Mulay |
Steve, you've hit upon a topic of interest to me with; "Class A generates a lot of waste heat but is lower distortion (and low power) and has a smoother sonic character (due to the harmonic structure of the output waveform). First, I've taken pains to come to understand that where distortion is concerned, the beauty of tube distortion rests with the output of EVEN ORDERED harmonics. My presumption would be that the "Class A" aspect of the MM's solid state pre-amp (see your post above), is responsible for outputting ODD ORDER (i.e. non-musical/harsh) harmonics. The signal then runs through an analog power output stage, thus, the harmonic output is what? Even ordered/chimey/musical? The tube distortion I use IN FRONT of my MM is an old Chandler Tube Driver. I think the Radial Tone Bone Classic would be killer also. THE biggest compliment anyone ever heaps on a MM amp is "it's loud". MUCH less is ever said about the amp's tone or signal musicality... Comment? Thanks. Marc Mulay | ||
| Steve Kennedy |
This is how I look at it... One of the hardest things for an amplifier to do is to amplify a wide variety of dynamic input sources to a loud audio level without imparting too much distortion & noise ("character") of its own. I am not talking about "hi-fi" here, but the ability to take all the output signal an active or humbucking pickup, preamp or stomp box can dish out without changing the sonic character of the input signal. When I play cleanly, I want the Telecaster or Stratocaster I'm playing to sound like the GUITAR, not the amp. If I cannot distinguish different guitars plugged into the amplifier then I am hearing the amp's sonic character and the guitar is just a signal generator. Under these conditions all the nuances of my playing will be lost or severly impaired by the "character" the amp throws over my guitar sound like a blanket. If I can get a great high-headroom clean sound with my amp, I know it has a better chance of passing any sort of distortion I choose to add ahead of the amp without changing the character of that distortion. So, if the amp preserves the odd-harmonics of the tube preamp I choose to use I could care less HOW it accomplishes this (Class A, A/B Single-ended, push pull, whatever). In my experience, an amp that is a great natural distortion generator usually has a limited range of tones and many of the best distortion generators suck at providing good clean tones. Many amps can't handle the output of active pickups or stomp boxes without their inputs creating additional distortion. That doesn't mean it doesn't sound good, but it becomes less controllable by the user and limits your control of the sound by simply adjusting your guitar volume. Amplifiers that are used as the primary distortion or "tone" generator are often limited to that one "sound" they are famous for. They will always sound basically like they do no matter what. That is a limitation. I own a Marshall and a Fender amp and enjoy them for what they are. While the Marshall excels at the "heavy" crunch stuff it is a tubby-sounding amp if you play clean with the humbucking pickups that drive it to distortion so well. The Fender (solid state Ultra Chorus 2-12") is a very versatile amp that is lightweight and needs no additional effects for casual use but even with 65 watts x 2 (stereo) is just isn't nearly as loud as my Music Man 410-65 (clean or otherwise). The Music Man amps I have are more sonically neutral and better at clean tones than any other amp I own. That isn't to say they would satisfy everyone, just me. There are more people that disagree with this point of view than agree with it, but it works for me and for me that's what is important. | ||
| Marc |
Your answer makes perfect sense, and, I agree with your observation, it just evaded answering the direct question I asked; "...My presumption would be that the "Class A" aspect of the MM's solid state pre-amp (see your post above), is responsible for outputting ODD ORDER (i.e. non-musical/harsh) harmonics. The signal then runs through an analog power output stage, thus, the harmonic output is what? Even ordered/chimey/musical?..." Perhaps the question was phrased incorrectly--- I am referring to output distortion and even ordered vs. odd ordered harmonics. Essentially, it's the age-old SS vs. analog (tube) question, re; distortion. The thing we all know is that given the ludicrous sheer VOLUME potential of the HD, attempts at driving it to distortion are plain stupid-- it's an amp designed to cleanly replicate input signal, so, in plain English, if it's chimey, musical, even-ordered harmonic distortion [aka "dirt"], you seek, accomplish it up front in your signal chain with whatever analog gear solution your own personal creativity and ear can assemble to suit your purpose, and AMPLIFY the VOLUME of that "tone" effectively using a transparent amp, like the MM; i.e. For the distortion character/aspect/portion of your tone, make sure that you use a good TUBE distortion effect...if not, the MM could easily wind up "garbage in, garbage out". Alternatively, it can wind up "Eric Johnson /David Gilmour in, Eric Johnson /David Gilmour out"  . | ||
| Mike MacLeod |
Radial Tonebone w/ MM I have a 2275 HD130R head, and while my Radial Tonebone sounds excellent with everything else I have used it with, it compresses the MM's signal and cuts off the bass response. Through an old Ampeg V4 4x12 cabinet the MM roars like a Trex. Mike | ||
| Steve Kennedy |
Better late than never... The way I see it, the solid-state preamp section of the Music Man amps are probably very low THD (Total Harmonic Distortion), much lower than the tube output stage. As long as you keep the preamp in clean territory everything is great and it is the tube output section that is contributing the majority of the distortion and "tonal quality"! If the preamp is overdriven, not only do you generate the "non-musical" odd-order harmonics, but you produce distortion waveforms that more closely approximate a squarewave than the preferred "rounded" overload distortion that a tube typically generates. Because solid-state electronics are so freaking "fast" (very quick rise-times and high-feedback) when compared to the relatively slow tube stages, they produce distortion spectra that go much higher in frequency than that generated by the tubes so it tends to sound shrill, spikey, fuzzy, "chainsaw-like", etc.. People have interesting ways of describing a sound (perhaps through visualization in some cases) that you can actually SEE on an oscilloscope and describe the waveform the same way! If you can pre-EQ the guitar signal coming into the preamp and post-EQ the output of the preamp before it gets to the tube output stage, you can roll-off a lot of this high-frequency junk and make the distortion much more palatable, especially if you process it through a tube processor along the way. I think a potentially better solution is to keep the preamp clean, overload the output stage and run the amp into a speaker emulator to capture the tubes overloading but keep things at a manageable level. An isolation speaker box could also be used (this probably sounds closer to a roaring speaker because it IS a real speaker and not an electronic approximation). Steve |
Tue, 03/25/2014 - 09:56
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