- Thread starter cky4ever
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maddog
Well-known member
it means tubes are used in a portion of the circuit that feeds the signal to the output devices (mosfets in this case)
oli@bass
Well-known member
SteveB
Well-known member
mosfet = metal oxide silicone field effect transistor, if I recall correctly.
Psycho Ward
Well-known member
I get kind of lost once you get past how to turn the amp on.
roballanson
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RobertB
Well-known member
So yeah, without needing to know or care about the details of mosfet's, the key thing to know is, like maddog and INMT said ... your amp has a tube driven (analog) preamp section, and a solid state (digital/transistor driven) front end/power amp. My SWR's the same way. It's a great set-up, in my opinion. The tube pre-amp really warms up the sound, while the solid-state front-end is very efficient at outputting the signal it receives from the pre-amp section at high power levels.
On my rig, the "Gain" controls the preamp level, and the "Master Volume" controls the power amp level. I typically boost the "Gain" until my hardest struck note barely activates the "clipping" LED (getting the maximum warmth/benefit from the tube), and then I set the desired overall volume/output level with the "Master Volume". The idea of this kind of a "hybrid" amp design is to give you the best of both worlds ... the warm tone of tube, and the power of solid-state.
On my rig, the "Gain" controls the preamp level, and the "Master Volume" controls the power amp level. I typically boost the "Gain" until my hardest struck note barely activates the "clipping" LED (getting the maximum warmth/benefit from the tube), and then I set the desired overall volume/output level with the "Master Volume". The idea of this kind of a "hybrid" amp design is to give you the best of both worlds ... the warm tone of tube, and the power of solid-state.
carpedebass
Well-known member
All we need now is a delorian and a stormy night and we can go back to the future..
No way! Still need a flux capacitor.
BTW...some truly nice googling done on the whole MOSFET thing in this thread! I suspect even some cut and paste?
strummer
Enormous Member
let's not get confused here, just because it has transistors in it does not make it "digital".
Ok, maybe the mesa amp has a class D power amp section, but that wouldn't have much to do with the transistors. Most transistor amps are A/B or simple B class mps
RobertB
Well-known member
You're right, my bad. Thanks for keeping me honest - I was unsure when I added "digital" to my statement, so I should've just skipped that part, being uncertain.
Whenever I think "transistor", I think "digital", because I'm more familir with those applications ... but it does depend on the application - computer memory/chips/IC's as opposed to amps & ?? (what are other examples of analog/non-digital applications/devices that use transistors?)
I guess ultimately whether a particular "transistorized" device/application is "digital" comes down to exactly what the transistors are doing in the app. If they're being used to represent binary digits (bits) used in arithmetic/logic operations (as in computer memory/chips/processors) ... it's a digital app. If they're being used purely to amplify signals, it may or may not be.
And that's not to say that all digital technologies use transistors, either. In fact, the earliest example of digital technology that I know of (no kidding), is communication using smoke signals. Because fundamentally, a "digital" signal is one in which the presence or absence of a pre-defined event over time tells you something (whether that event be an electrical voltage/current, or a smoke signal!), whereas an "analog" signal is one in which some attribute of the signal (frequency, amplitude, phase, for example) is varied continuously over time in a way that is "analogous" to the original/souce information being transmitted.
That may be a communications-centric view, and I'm not trying to sound knowledgeable here. Just thought that since it came up, it may be a topic some may be interested in discussing a bit. I know just enough about this stuff to get myself into trouble. I work with wireless systems, but I'm not a hardware guy.
Edit: and I want to know more about hardware/electronics, particularly amps! So fire away if you care to. I think the name of this thread already sufficiently identifies it as that type of thread.
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TNT
Well-known member
In my opinion, it was more of a "backward" thing they were doing on those.
Having a solid state and/or digital appliance driving the "pre-amp" section, then feeding that signal to the "valve" driven power output is the way to go!!. (tons of articles on this out there).
Maintains many qualities of a tube driven amp (if that's what they want?).
Having a solid state and/or digital appliance driving the "pre-amp" section, then feeding that signal to the "valve" driven power output is the way to go!!. (tons of articles on this out there).
Maintains many qualities of a tube driven amp (if that's what they want?).
slow roasted
Well-known member
- Joined
- Jan 15, 2008
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- 138
Tube driven Mosfets = marketing phrase.
You have some 12AX7 tubes in the preamp. This preamp is designed to sound a lot like an Ampeg SVT preamp to my ears. They also use a 12AX7 to feed the solid state poweramp portion of the head. This is designed ( at least in theory) to give you a nice tube "rock" head sound without the hassle. Gets pretty close IMHO. The gain and master controls are very interactive on Boogies, and experimenting can get you many variations of tone from fairly clean to very squashed and dirty.
You can also change the 12AX7 pre tubes for a different manufacturer to change the tone as well, but they are designed around the tube Boogie uses. And you get maximum variation from those OEM tubes IMO...
You have some 12AX7 tubes in the preamp. This preamp is designed to sound a lot like an Ampeg SVT preamp to my ears. They also use a 12AX7 to feed the solid state poweramp portion of the head. This is designed ( at least in theory) to give you a nice tube "rock" head sound without the hassle. Gets pretty close IMHO. The gain and master controls are very interactive on Boogies, and experimenting can get you many variations of tone from fairly clean to very squashed and dirty.
You can also change the 12AX7 pre tubes for a different manufacturer to change the tone as well, but they are designed around the tube Boogie uses. And you get maximum variation from those OEM tubes IMO...
RobertB
Well-known member
Sounds cool. I wonder what the considerations/trade-offs are, for one versus the other. For example, I remember reading years ago that there are distinct advantages to having your eq levels set in a tube preamp, as opposed to a solid state preamp. I don't remember the claim as to why that is, though.
So many people are into high power/high wattage amps these days .. they want to see a big number, which supposedly solid state power amps are better/more efficient at generating. But the argument to that, would be that with all-tube amps, you don't NEED as much power output to sound as loud. I remember looking around at a certain point and noticing that, indeed, I couldn't find a single 1000W all tube head ... atleast at the time I was looking at it, maybe about 5 years ago, they were all in the much lower ranges, in terms of power output. But the argument goes that a 300W all tube amp sounds just as loud as, AND warmer than, a 1000W solid state head. I know there's a ton of discussion/debate about this. I always say just leave it up to your own ears to decide where you stand on it.
So many people are into high power/high wattage amps these days .. they want to see a big number, which supposedly solid state power amps are better/more efficient at generating. But the argument to that, would be that with all-tube amps, you don't NEED as much power output to sound as loud. I remember looking around at a certain point and noticing that, indeed, I couldn't find a single 1000W all tube head ... atleast at the time I was looking at it, maybe about 5 years ago, they were all in the much lower ranges, in terms of power output. But the argument goes that a 300W all tube amp sounds just as loud as, AND warmer than, a 1000W solid state head. I know there's a ton of discussion/debate about this. I always say just leave it up to your own ears to decide where you stand on it.
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SteveB
Well-known member
bassmancb
Well-known member
Congrats on your Mesa. Enjoy!!! I know I enjoy mine!
TNT
Well-known member
Steve,
Thanks for the "tip". I've never checked out those MOSvalves power amps - BUT now that you mention it, I will do so!!
Thanks for the "tip". I've never checked out those MOSvalves power amps - BUT now that you mention it, I will do so!!
oli@bass
Well-known member
AFAIK, that's largely due to the fact that tubes compress the signal (by clipping), and therefore sound louder. It's the same principle as mixing "loud" CDs.... they're not acutally louder, they have no dynamics left... a tube can do that, and even sound nice while doing it, because it also produces harmonics when clipping.
